Shenfeng Qiu

Interests

Research

Neurodevelopmental and neuropsychiatric disordersGenetic basis of neurodevelopmental disorders and risk genesneural and brain circuit basis of autism

Teaching

CBI, neurological science blockCBI, GIMDO blockCBI, neuromusculoskeletal blockLectures: Cell and Neurobiology of Brain development

Courses

Scholarly Contributions

Chapters

• Xu, Y., Xu, J., Qiu, S., & Tu, W. (2023). Molecular Biomarkers in the Prediction, Diagnosis, and Prognosis of Neurodegenerative Diseases. In Molecular Biomarkers in the Prediction. doi:10.3389/978-2-8325-2786-3
• Qiu, S., & Weeber, E. J. (2008). Reelin and cognition. In Reelin Glycoprotein. Springer, New York, NY. doi:10.1007/978-0-387-76761-1_12
• Qiu, S. -., & Weeber, E. J. (2007). Reelin and cognition. In Reelin Glycoprotein, biology, structure and roles in health and disease. Springer.

Journals/Publications

• Cui, Y., Ma, X., Wei, J., Chen, C., Shakir, N., Guirram, H., Dai, Z., Anderson, T., Ferguson, D., & Qiu, S. (2024). MET receptor tyrosine kinase promotes the generation of functional synapses in adult cortical circuits. Neural Regeneration Research. doi:10.4103/nrr.nrr-d-23-01471
• Kim, H., Wei, J., Call, T., Ma, X., Quintus, N., Summers, A., Carotenuto, S., Johnson, R., Nguyen, A., Cui, Y., Park, J., Qiu, S., & Ferguson, D. (2024). SIRT1 Coordinates Transcriptional Regulation of Neural Activity and Modulates Depression-Like Behaviors in the Nucleus Accumbens. Biological Psychiatry, 96(6). doi:10.1016/j.biopsych.2024.03.017
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  Background: Major depression and anxiety disorders are significant causes of disability and socioeconomic burden. Despite the prevalence and considerable impact of these affective disorders, their pathophysiology remains elusive. Thus, there is an urgent need to develop novel therapeutics for these conditions. We evaluated the role of SIRT1 in regulating dysfunctional processes of reward by using chronic social defeat stress to induce depression- and anxiety-like behaviors. Chronic social defeat stress induces physiological and behavioral changes that recapitulate depression-like symptomatology and alters gene expression programs in the nucleus accumbens, but cell type–specific changes in this critical structure remain largely unknown. Methods: We examined transcriptional profiles of D1-expressing medium spiny neurons (MSNs) lacking deacetylase activity of SIRT1 by RNA sequencing in a cell type–specific manner using the RiboTag line of mice. We analyzed differentially expressed genes using gene ontology tools including SynGO and EnrichR and further demonstrated functional changes in D1-MSN–specific SIRT1 knockout (KO) mice using electrophysiological and behavioral measurements. Results: RNA sequencing revealed altered transcriptional profiles of D1-MSNs lacking functional SIRT1 and showed specific changes in synaptic genes including glutamatergic and GABAergic (gamma-aminobutyric acidergic) receptors in D1-MSNs. These molecular changes may be associated with decreased excitatory and increased inhibitory neural activity in Sirt1 KO D1-MSNs, accompanied by morphological changes. Moreover, the D1-MSN–specific Sirt1 KO mice exhibited proresilient changes in anxiety- and depression-like behaviors. Conclusions: SIRT1 coordinates excitatory and inhibitory synaptic genes to regulate the GABAergic output tone of D1-MSNs. These findings reveal a novel signaling pathway that has potential for the development of innovative treatments for affective disorders.
• Lai, W., Zhao, Y., Chen, Y., Dai, Z., Chen, R., Niu, Y., Chen, X., Chen, S., Huang, G., Shan, Z., Zheng, J., Hu, Y., Chen, Q., Gong, S., Kang, S., Guo, H., Ma, X., Song, Y., Xia, K., , Wang, J., et al. (2024). Autism patient-derived SHANK2B mutation affects the development of ALDH1A1 negative dopamine neuron. Molecular psychiatry, 29(10), 3180-3194.
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  Autism spectrum disorder (ASD) encompasses a range of neurodevelopmental conditions. Different mutations on a single ASD gene contribute to heterogeneity of disease phenotypes, possibly due to functional diversity of generated isoforms. SHANK2, a causative gene in ASD, demonstrates this phenomenon, but there is a scarcity of tools for studying endogenous SHANK2 proteins in an isoform-specific manner. Here, we report a point mutation on SHANK2, which is found in a patient with autism, located on exon of the SHANK2B transcript variant (NM_133266.5), hereby SHANK2B. This mutation results in an early stop codon and an aberrant splicing event that impacts SHANK2 transcript variants distinctly. Induced pluripotent stem cells (iPSCs) carrying this mutation, from the patient or isogenic editing, fail to differentiate into functional dopamine (DA) neurons, which can be rescued by genetic correction. Available SMART-Seq single-cell data from human midbrain reveals the abundance of SHANK2B transcript in the ALDH1A1 negative DA neurons. We then show that SHANK2B mutation primarily affects SHANK2B expression and ALDH1A1 negative DA neurons in vitro during early neuronal developmental stage. Mice knocked in with the identical mutation exhibit autistic-like behavior, decreased occupancy of ALDH1A1 negative DA neurons and decreased dopamine release in ventral tegmental area (VTA). Our study provides novel insights on a SHANK2 mutation derived from autism patient and highlights SHANK2B significance in ALDH1A1 negative DA neuron.
• Lai, W., Zhao, Y., Chen, Y., Dai, Z., Chen, R., Niu, Y., Chen, X., Chen, S., Huang, G., Shan, Z., Zheng, J., Hu, Y., Chen, Q., Gong, S., Kang, S., Guo, H., Ma, X., Song, Y., Xia, K., , Wang, J., et al. (2024). Autism patient-derived SHANK2BY29X mutation affects the development of ALDH1A1 negative dopamine neuron. Molecular Psychiatry, 29(10). doi:10.1038/s41380-024-02578-6
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  Autism spectrum disorder (ASD) encompasses a range of neurodevelopmental conditions. Different mutations on a single ASD gene contribute to heterogeneity of disease phenotypes, possibly due to functional diversity of generated isoforms. SHANK2, a causative gene in ASD, demonstrates this phenomenon, but there is a scarcity of tools for studying endogenous SHANK2 proteins in an isoform-specific manner. Here, we report a point mutation on SHANK2, which is found in a patient with autism, located on exon of the SHANK2B transcript variant (NM_133266.5), hereby SHANK2BY29X. This mutation results in an early stop codon and an aberrant splicing event that impacts SHANK2 transcript variants distinctly. Induced pluripotent stem cells (iPSCs) carrying this mutation, from the patient or isogenic editing, fail to differentiate into functional dopamine (DA) neurons, which can be rescued by genetic correction. Available SMART-Seq single-cell data from human midbrain reveals the abundance of SHANK2B transcript in the ALDH1A1 negative DA neurons. We then show that SHANK2BY29X mutation primarily affects SHANK2B expression and ALDH1A1 negative DA neurons in vitro during early neuronal developmental stage. Mice knocked in with the identical mutation exhibit autistic-like behavior, decreased occupancy of ALDH1A1 negative DA neurons and decreased dopamine release in ventral tegmental area (VTA). Our study provides novel insights on a SHANK2 mutation derived from autism patient and highlights SHANK2B significance in ALDH1A1 negative DA neuron.
• Liu, B., Yi, D., Ma, X., Ramirez, K., Zhao, H., Xia, X., Fallon, M. B., Kalinichenko, V. V., Qiu, S., & Dai, Z. (2024). A Novel Animal Model for Pulmonary Hypertension: Lung Endothelial-Specific Deletion of in Mice. Journal of respiratory biology and translational medicine, 1(2).
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  Pulmonary arterial hypertension (PAH) is a devastating disease characterized by high blood pressure in the pulmonary arteries, which can potentially lead to heart failure over time. Previously, our lab found that endothelia-specific knockout of , encoding prolyl 4-hydroxylase-2 (PHD2), induced spontaneous pulmonary hypertension (PH). Recently, we elucidated that is a lung-specific endothelial gene using mice. We hypothesize that lung endothelial-specific deletion of could lead to the development of PH without affecting gene expression in other organs. em-CreERT2 mice were crossed with mice to generate (LiCKO) mice. Western blot and immunofluorescent staining were performed to verify the knockout efficacy of in multiple organs of LiCKO mice. PH phenotypes, including hemodynamics, right heart size and function, pulmonary vascular remodeling, were evaluated by right heart catheterization and echocardiography measurements. Tamoxifen treatment induced deletion in the lung endothelial cells (ECs) but not in other organs of adult LiCKO mice. LiCKO mice exhibited an increase in right ventricular systolic pressure (RVSP, ~35 mmHg) and right heart hypertrophy. Echocardiography measurements showed right heart hypertrophy, as well as cardiac and pulmonary arterial dysfunction. Pulmonary vascular remodeling, including increased pulmonary wall thickness and muscularization of distal pulmonary arterials, was enhanced in LiCKO mice compared to wild-type mice. promoter-mediated lung endothelial knockout of in mice leads to development of spontaneous PH. LiCKO mice could serve as a novel mouse model for PH to study lung and other organ crosstalk.
• Liu, B., Yi, D., Xia, X., Ramirez, K., Zhao, H., Cao, Y., Tripathi, A., Dong, R., Gao, A., Ding, H., Qiu, S., Kalinichenko, V., Zhao, Y., Fallon, M., & Dai, Z. (2024). General Capillary Endothelial Cells Undergo Reprogramming Into Arterial Endothelial Cells in Pulmonary Hypertension Through HIF-2α/Notch4 Pathway. Circulation, 150(5). doi:10.1161/CIRCULATIONAHA.123.067981
• Ma, X., Chen, P., Wei, J., Zhang, J., Chen, C., Zhao, H., Ferguson, D., McGee, A., Dai, Z., & Qiu, S. (2024). Protocol for Xenium spatial transcriptomics studies using fixed frozen mouse brain sections. STAR Protocols, 5(4). doi:10.1016/j.xpro.2024.103420
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  Here, we present a protocol for Xenium spatial transcriptomics studies using fixed frozen mouse brain sections. We describe steps for intracardiac perfusion, cryosectioning, and floating section mounting of brain sections, which enable runs on the Xenium analyzer and data delivery. We demonstrate that, in addition to the 10× Genomics-validated formalin-fixed paraffin-embedded (FFPE) and fresh frozen sections, fixed frozen thin brain sections are compatible with the Xenium platform and provide excellent imaging and quantification results for spatially resolved gene expression. For complete details on the use and execution of this protocol, please refer to Ma et al.1
• Qiu, S., Ferguson, D., Wei, J., Chen, C., Ma, X., Zhang, L., Cui, Y., Bai, F., Xia, B., & Shakir, N. (2023). Disrupted Maturation of Prefrontal Layer 5 Neuronal Circuits in an Alzheimer's Mouse Model of Amyloid Deposition.. Neuroscience Bulletin.
• Shen, L., Ma, X., Wang, Y., Wang, Z., Zhang, Y., Pham, H., Tao, X., Cui, Y., Wei, J., Lin, D., Abeywanada, T., Hardikar, S., Halabelian, L., Smith, N., Chen, T., Barsyte-Lovejoy, D., Qiu, S., Xing, Y., & Yang, Y. (2024). Loss-of-function mutation in PRMT9 causes abnormal synapse development by dysregulation of RNA alternative splicing. Nature Communications, 15(1). doi:10.1038/s41467-024-47107-9
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  Protein arginine methyltransferase 9 (PRMT9) is a recently identified member of the PRMT family, yet its biological function remains largely unknown. Here, by characterizing an intellectual disability associated PRMT9 mutation (G189R) and establishing a Prmt9 conditional knockout (cKO) mouse model, we uncover an important function of PRMT9 in neuronal development. The G189R mutation abolishes PRMT9 methyltransferase activity and reduces its protein stability. Knockout of Prmt9 in hippocampal neurons causes alternative splicing of ~1900 genes, which likely accounts for the aberrant synapse development and impaired learning and memory in the Prmt9 cKO mice. Mechanistically, we discover a methylation-sensitive protein–RNA interaction between the arginine 508 (R508) of the splicing factor 3B subunit 2 (SF3B2), the site that is exclusively methylated by PRMT9, and the pre-mRNA anchoring site, a cis-regulatory element that is critical for RNA splicing. Additionally, using human and mouse cell lines, as well as an SF3B2 arginine methylation-deficient mouse model, we provide strong evidence that SF3B2 is the primary methylation substrate of PRMT9, thus highlighting the conserved function of the PRMT9/SF3B2 axis in regulating pre-mRNA splicing.
• Xu, Y., Qiu, S., Tu, W., & Xu, J. (2023). Editorial: Molecular biomarkers in the prediction, diagnosis, and prognosis of neurodegenerative diseases. Frontiers in Neuroscience, 17. doi:10.3389/fnins.2023.1226675
• Chen, C., Ma, X., Wei, J., Shakir, N., Zhang, J. K., Zhang, L., Nehme, A., Cui, Y., Ferguson, D., Bai, F., & Qiu, S. (2022). Early impairment of cortical circuit plasticity and connectivity in the 5XFAD Alzheimer's disease mouse model. Translational psychiatry, 12(1), 371.
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  Genetic risk factors for neurodegenerative disorders, such as Alzheimer's disease (AD), are expressed throughout the life span. How these risk factors affect early brain development and function remain largely unclear. Analysis of animal models with high constructive validity for AD, such as the 5xFAD mouse model, may provide insights on potential early neurodevelopmental effects that impinge on adult brain function and age-dependent degeneration. The 5XFAD mouse model over-expresses human amyloid precursor protein (APP) and presenilin 1 (PS1) harboring five familial AD mutations. It is unclear how the expression of these mutant proteins affects early developing brain circuits. We found that the prefrontal cortex (PFC) layer 5 (L5) neurons in 5XFAD mice exhibit transgenic APP overloading at an early post-weaning age. Impaired synaptic plasticity (long-term potentiation, LTP) was seen at 6-8 weeks age in L5 PFC circuit, which was correlated with increased intracellular APP. APP overloading was also seen in L5 pyramidal neurons in the primary visual cortex (V1) during the critical period of plasticity (4-5 weeks age). Whole-cell patch clamp recording in V1 brain slices revealed reduced intrinsic excitability of L5 neurons in 5XFAD mice, along with decreased spontaneous miniature excitatory and inhibitory inputs. Functional circuit mapping using laser scanning photostimulation (LSPS) combined with glutamate uncaging uncovered reduced excitatory synaptic connectivity onto L5 neurons in V1, and a more pronounced reduction in inhibitory connectivity, indicative of altered excitation and inhibition during VC critical period. Lastly, in vivo single-unit recording in V1 confirmed that monocular visual deprivation-induced ocular dominance plasticity during critical period was impaired in 5XFAD mice. Our study reveals plasticity deficits across multiple cortical regions and indicates altered early cortical circuit developmental trajectory as a result of mutant APP/PS1 over-expression.
• Chen, C., Wei, J., Ma, X., Xia, B., Shakir, N., Zhang, J. K., Zhang, L., Cui, Y., Ferguson, D., Qiu, S., & Bai, F. (2022). Disrupted Maturation of Prefrontal Layer 5 Neuronal Circuits in an Alzheimer's Mouse Model of Amyloid Deposition. Neuroscience bulletin.
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  Mutations in genes encoding amyloid precursor protein (APP) and presenilins (PSs) cause familial forms of Alzheimer's disease (AD), a neurodegenerative disorder strongly associated with aging. It is currently unknown whether and how AD risks affect early brain development, and to what extent subtle synaptic pathology may occur prior to overt hallmark AD pathology. Transgenic mutant APP/PS1 over-expression mouse lines are key tools for studying the molecular mechanisms of AD pathogenesis. Among these lines, the 5XFAD mice rapidly develop key features of AD pathology and have proven utility in studying amyloid plaque formation and amyloid β (Aβ)-induced neurodegeneration. We reasoned that transgenic mutant APP/PS1 over-expression in 5XFAD mice may lead to neurodevelopmental defects in early cortical neurons, and performed detailed synaptic physiological characterization of layer 5 (L5) neurons from the prefrontal cortex (PFC) of 5XFAD and wild-type littermate controls. L5 PFC neurons from 5XFAD mice show early APP/Aβ immunolabeling. Whole-cell patch-clamp recording at an early post-weaning age (P22-30) revealed functional impairments; although 5XFAD PFC-L5 neurons exhibited similar membrane properties, they were intrinsically less excitable. In addition, these neurons received smaller amplitude and frequency of miniature excitatory synaptic inputs. These functional disturbances were further corroborated by decreased dendritic spine density and spine head volumes that indicated impaired synapse maturation. Slice biotinylation followed by Western blot analysis of PFC-L5 tissue revealed that 5XFAD mice showed reduced synaptic AMPA receptor subunit GluA1 and decreased synaptic NMDA receptor subunit GluN2A. Consistent with this, patch-clamp recording of the evoked L23>L5 synaptic responses revealed a reduced AMPA/NMDA receptor current ratio, and an increased level of AMPAR-lacking silent synapses. These results suggest that transgenic mutant forms of APP/PS1 overexpression in 5XFAD mice leads to early developmental defects of cortical circuits, which could contribute to the age-dependent synaptic pathology and neurodegeneration later in life.
• Wei, J., Ma, X., Nehme, A., Cui, Y., Zhang, L., & Qiu, S. (2022). Reduced HGF/MET Signaling May Contribute to the Synaptic Pathology in an Alzheimer's Disease Mouse Model. Frontiers in aging neuroscience, 14, 954266.
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  Alzheimer's disease (AD) is a neurodegenerative disorder strongly associates with aging. While amyloid plagues and neurofibrillary tangles are pathological hallmarks of AD, recent evidence suggests synaptic dysfunction and physical loss may be the key mechanisms that determine the clinical syndrome and dementia onset. Currently, no effective therapy prevents neuropathological changes and cognitive decline. Neurotrophic factors and their receptors represent novel therapeutic targets to treat AD and dementia. Recent clinical literature revealed that MET receptor tyrosine kinase protein is reduced in AD patient's brain. Activation of MET by its ligand hepatocyte growth factor (HGF) initiates pleiotropic signaling in the developing brain that promotes neurogenesis, survival, synaptogenesis, and plasticity. We hypothesize that if reduced MET signaling plays a role in AD pathogenesis, this might be reflected in the AD mouse models and as such provides opportunities for mechanistic studies on the role of HGF/MET in AD. Examining the 5XFAD mouse model revealed that MET protein exhibits age-dependent progressive reduction prior to overt neuronal pathology, which cannot be explained by indiscriminate loss of total synaptic proteins. In addition, genetic ablation of MET protein in cortical excitatory neurons exacerbates amyloid-related neuropathology in 5XFAD mice. We further found that HGF enhances prefrontal layer 5 neuron synaptic plasticity measured by long-term potentiation (LTP). However, the degree of LTP enhancement is significantly reduced in 5XFAD mice brain slices. Taken together, our study revealed that early reduction of HGF/MET signaling may contribute to the synaptic pathology observed in AD.
• Wei, J., Zuo, Y., Zhang, L., Xia, B., Qiu, S., Nehme, A., Ma, X., Levitt, P., Ferguson, D., & Cui, Y. (2022). Disrupted Timing of MET Signaling Derails the Developmental Maturation of Cortical Circuits and Leads to Altered Behavior in Mice.. Cerebral cortex (New York, N.Y. : 1991), 32(8), 1769-1786. doi:10.1093/cercor/bhab323
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  The molecular regulation of the temporal dynamics of circuit maturation is a key contributor to the emergence of normal structure-function relations. Developmental control of cortical MET receptor tyrosine kinase, expressed early postnatally in subpopulations of excitatory neurons, has a pronounced impact on the timing of glutamatergic synapse maturation and critical period plasticity. Here, we show that using a controllable overexpression (cto-Met) transgenic mouse, extending the duration of MET signaling after endogenous Met is switched off leads to altered molecular constitution of synaptic proteins, persistent activation of small GTPases Cdc42 and Rac1, and sustained inhibitory phosphorylation of cofilin. These molecular changes are accompanied by an increase in the density of immature dendritic spines, impaired cortical circuit maturation of prefrontal cortex layer 5 projection neurons, and altered laminar excitatory connectivity. Two photon in vivo imaging of dendritic spines reveals that cto-Met enhances de novo spine formation while inhibiting spine elimination. Extending MET signaling for two weeks in developing cortical circuits leads to pronounced repetitive activity and impaired social interactions in adult mice. Collectively, our data revealed that temporally controlled MET signaling as a critical mechanism for controlling cortical circuit development and emergence of normal behavior.
• Kim, H. D., Wei, J., Call, T., Quintus, N. T., Summers, A. J., Carotenuto, S., Johnson, R., Ma, X., Xu, C., Park, J. G., Qiu, S., & Ferguson, D. (2021). Shisa6 mediates cell-type specific regulation of depression in the nucleus accumbens. Molecular psychiatry.
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  Depression is the leading cause of disability and produces enormous health and economic burdens. Current treatment approaches for depression are largely ineffective and leave more than 50% of patients symptomatic, mainly because of non-selective and broad action of antidepressants. Thus, there is an urgent need to design and develop novel therapeutics to treat depression. Given the heterogeneity and complexity of the brain, identification of molecular mechanisms within specific cell-types responsible for producing depression-like behaviors will advance development of therapies. In the reward circuitry, the nucleus accumbens (NAc) is a key brain region of depression pathophysiology, possibly based on differential activity of D1- or D2- medium spiny neurons (MSNs). Here we report a circuit- and cell-type specific molecular target for depression, Shisa6, recently defined as an AMPAR component, which is increased only in D1-MSNs in the NAc of susceptible mice. Using the Ribotag approach, we dissected the transcriptional profile of D1- and D2-MSNs by RNA sequencing following a mouse model of depression, chronic social defeat stress (CSDS). Bioinformatic analyses identified cell-type specific genes that may contribute to the pathogenesis of depression, including Shisa6. We found selective optogenetic activation of the ventral tegmental area (VTA) to NAc circuit increases Shisa6 expression in D1-MSNs. Shisa6 is specifically located in excitatory synapses of D1-MSNs and increases excitability of neurons, which promotes anxiety- and depression-like behaviors in mice. Cell-type and circuit-specific action of Shisa6, which directly modulates excitatory synapses that convey aversive information, identifies the protein as a potential rapid-antidepressant target for aberrant circuit function in depression.
• Lifshitz, J., Qiu, S., Ortiz, J. B., Saber, M., Rojas Valencia, L. M., Ma, X., Tallent, B. R., Adelson, P. D., & Rowe, R. K. (2021). Mice Born to Mothers with Gravida Traumatic Brain Injury Have Distorted Brain Circuitry and Altered Immune Responses. Journal of Neurotrauma, 38(20), 2862-2880. doi:10.1089/neu.2021.0048
• Ma, X., Wei, J., Cui, Y., Xia, B., Zhang, L., Nehme, A., Zuo, Y., Ferguson, D., Levitt, P., & Qiu, S. (2021). Disrupted Timing of MET Signaling Derails the Developmental Maturation of Cortical Circuits and Leads to Altered Behavior in Mice. Cerebral cortex (New York, N.Y. : 1991).
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  The molecular regulation of the temporal dynamics of circuit maturation is a key contributor to the emergence of normal structure-function relations. Developmental control of cortical MET receptor tyrosine kinase, expressed early postnatally in subpopulations of excitatory neurons, has a pronounced impact on the timing of glutamatergic synapse maturation and critical period plasticity. Here, we show that using a controllable overexpression (cto-Met) transgenic mouse, extending the duration of MET signaling after endogenous Met is switched off leads to altered molecular constitution of synaptic proteins, persistent activation of small GTPases Cdc42 and Rac1, and sustained inhibitory phosphorylation of cofilin. These molecular changes are accompanied by an increase in the density of immature dendritic spines, impaired cortical circuit maturation of prefrontal cortex layer 5 projection neurons, and altered laminar excitatory connectivity. Two photon in vivo imaging of dendritic spines reveals that cto-Met enhances de novo spine formation while inhibiting spine elimination. Extending MET signaling for two weeks in developing cortical circuits leads to pronounced repetitive activity and impaired social interactions in adult mice. Collectively, our data revealed that temporally controlled MET signaling as a critical mechanism for controlling cortical circuit development and emergence of normal behavior.
• Saber, M., Ortiz, J. B., Rojas Valencia, L. M., Ma, X., Tallent, B. R., Adelson, P. D., Rowe, R. K., Qiu, S., & Lifshitz, J. (2021). Mice Born to Mothers with Gravida Traumatic Brain Injury Have Distorted Brain Circuitry and Altered Immune Responses. Journal of neurotrauma, 38(20), 2862-2880.
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  Intimate partner violence (IPV) increases risk of traumatic brain injury (TBI). Physical assaults increase in frequency and intensity during pregnancy. The consequences of TBI during pregnancy (gravida TBI; gTBI) on offspring development is unknown, for which stress and inflammation during pregnancy worsen fetal developmental outcomes. We hypothesized that gTBI would lead to increased anxiety- and depression-related behavior, altered inflammatory responses and gut pathology, and distorted brain circuitry in mixed-sex offspring compared to mice born to control mothers. Pregnant dams received either diffuse TBI or sham injury (control) 12 days post-coitum. We found that male gTBI offspring were principal drivers of the gTBI effects on health, physiology, and behavior. For example, male, but not female, gTBI offspring weighed significantly less at weaning compared to male control offspring. At post-natal day (PND) 28, gTBI offspring had significantly weaker intralaminar connectivity onto layer 5 pre-frontal pyramidal neurons compared to control offspring. Neurological performance on anxiety-like behaviors was decreased, with only marginal differences in depressive-like behaviors, for gTBI offspring compared to control offspring. At PND42 and PND58, circulating neutrophil and monocyte populations were significantly smaller in gTBI male offspring than control male offspring. In response to a subsequent inflammatory challenge at PND75, gTBI offspring had significantly smaller circulating neutrophil populations than control offspring. Anxiety-like behaviors persisted during the immune challenge in gTBI offspring. However, spleen immune response and gut histology showed no significant differences between groups. The results compel further studies to determine the full extent of gTBI on fetal and maternal outcomes.
• Tsyporin, J., Tastad, D., Ma, X., Nehme, A., Finn, T., Huebner, L., Liu, G., Gallardo, D., Makhamreh, A., Roberts, J. M., Katzman, S., Sestan, N., McConnell, S. K., Yang, Z., Qiu, S., & Chen, B. (2021). Transcriptional repression by FEZF2 restricts alternative identities of cortical projection neurons. Cell reports, 35(12), 109269.
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  Projection neuron subtype identities in the cerebral cortex are established by expressing pan-cortical and subtype-specific effector genes that execute terminal differentiation programs bestowing neurons with a glutamatergic neuron phenotype and subtype-specific morphology, physiology, and axonal projections. Whether pan-cortical glutamatergic and subtype-specific characteristics are regulated by the same genes or controlled by distinct programs remains largely unknown. Here, we show that FEZF2 functions as a transcriptional repressor, and it regulates subtype-specific identities of both corticothalamic and subcerebral neurons by selectively repressing expression of genes inappropriate for each neuronal subtype. We report that TLE4, specifically expressed in layer 6 corticothalamic neurons, is recruited by FEZF2 to inhibit layer 5 subcerebral neuronal genes. Together with previous studies, our results indicate that a cortical glutamatergic identity is specified by multiple parallel pathways active in progenitor cells, whereas projection neuron subtype-specific identity is achieved through selectively repressing genes associated with alternate identities in differentiating neurons.
• Xia, B., Wei, J., Ma, X., Nehme, A., Liong, K., Cui, Y., Chen, C., Gallitano, A., Ferguson, D., & Qiu, S. (2021). Conditional knockout of MET receptor tyrosine kinase in cortical excitatory neurons leads to enhanced learning and memory in young adult mice but early cognitive decline in older adult mice. Neurobiology of learning and memory, 179, 107397.
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  Human genetic studies established MET gene as a risk factor for autism spectrum disorders. We have previously shown that signaling mediated by MET receptor tyrosine kinase, expressed in early postnatal developing forebrain circuits, controls glutamatergic neuron morphological development, synapse maturation, and cortical critical period plasticity. Here we investigated how MET signaling affects synaptic plasticity, learning and memory behavior, and whether these effects are age-dependent. We found that in young adult (postnatal 2-3 months) Met conditional knockout (Met:emx1, cKO) mice, the hippocampus exhibits elevated plasticity, measured by increased magnitude of long-term potentiation (LTP) and depression (LTD) in hippocampal slices. Surprisingly, in older adult cKO mice (10-12 months), LTP and LTD magnitudes were diminished. We further conducted a battery of behavioral tests to assess learning and memory function in cKO mice and littermate controls. Consistent with age-dependent LTP/LTD findings, we observed enhanced spatial memory learning in 2-3 months old young adult mice, assessed by hippocampus-dependent Morris water maze test, but impaired spatial learning in 10-12 months mice. Contextual and cued learning were further assessed using a Pavlovian fear conditioning test, which also revealed enhanced associative fear acquisition and extinction in young adult mice, but impaired fear learning in older adult mice. Lastly, young cKO mice also exhibited enhanced motor learning. Our results suggest that a shift in the window of synaptic plasticity and an age-dependent early cognitive decline may be novel circuit pathophysiology for a well-established autism genetic risk factor.
• Chen, K., Ma, X., Nehme, A., Wei, J., Cui, Y., Cui, Y., Yao, D., Wu, J., Anderson, T., Ferguson, D., Levitt, P., & Qiu, S. (2020). Time-delimited signaling of MET receptor tyrosine kinase regulates cortical circuit development and critical period plasticity. Molecular psychiatry.
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  Normal development of cortical circuits, including experience-dependent cortical maturation and plasticity, requires precise temporal regulation of gene expression and molecular signaling. Such regulation, and the concomitant impact on plasticity and critical periods, is hypothesized to be disrupted in neurodevelopmental disorders. A protein that may serve such a function is the MET receptor tyrosine kinase, which is tightly regulated developmentally in rodents and primates, and exhibits reduced cortical expression in autism spectrum disorder and Rett Syndrome. We found that the peak of MET expression in developing mouse cortex coincides with the heightened period of synaptogenesis, but is precipitously downregulated prior to extensive synapse pruning and certain peak periods of cortical plasticity. These results reflect a potential on-off regulatory synaptic mechanism for specific glutamatergic cortical circuits in which MET is enriched. In order to address the functional significance of the 'off' component of the proposed mechanism, we created a controllable transgenic mouse line that sustains cortical MET signaling. Continued MET expression in cortical excitatory neurons disrupted synaptic protein profiles, altered neuronal morphology, and impaired visual cortex circuit maturation and connectivity. Remarkably, sustained MET signaling eliminates monocular deprivation-induced ocular dominance plasticity during the normal cortical critical period; while ablating MET signaling leads to early closure of critical period plasticity. The results demonstrate a novel mechanism in which temporal regulation of a pleiotropic signaling protein underlies cortical circuit maturation and timing of cortical critical period, features that may be disrupted in neurodevelopmental disorders.
• Gao, M., Der-Ghazarian, T. S., Li, S., Qiu, S., Neisewander, J. L., & Wu, J. (2020). Dual Effect of 5-HT Receptors on Dopamine Neurons in Ventral Tegmental Area: Implication for the Functional Switch After Chronic Cocaine Exposure. Biological psychiatry, 88(12), 922-934.
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  Serotonin (5-HT) 1B/1D receptor (5-HTR) agonists undergo an abstinence-induced switch in their effects on cocaine-related behaviors, which may involve changes in modulation of dopamine (DA) neurons in the ventral tegmental area (VTA). However, it is unclear how 5-HTRs affect VTA DA neuronal function and whether modulation of these neurons mediates the abstinence-induced switch after chronic cocaine exposure.
• Hastings, K. T., Qiu, S., Rausch, M. P., Meador, L. R., Metzger, T. C., Li, H., & Anderson, M. S. (2020). GILT in Thymic Epithelial Cells Facilitates Central CD4 T Cell Tolerance to a Tissue-Restricted, Melanoma-Associated Self-Antigen. The Journal of Immunology, 204(11), 2877-2886. doi:10.4049/jimmunol.1900523
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  Abstract Central tolerance prevents autoimmunity, but also limits T cell responses to potentially immunodominant tumor epitopes with limited expression in healthy tissues. In peripheral antigen presenting cells (APCs), gamma-interferon-inducible lysosomal thiol reductase (GILT) is critical for MHC class II-restricted presentation of disulfide bond-containing proteins, including the self and melanoma antigen tyrosinase-related protein 1 (TRP1). The role of GILT in thymic antigen processing and generation of central tolerance has not been investigated. We found that GILT enhanced the negative selection of TRP1-specific thymocytes. GILT expression was enriched in thymic APCs capable of mediating deletion, namely medullary thymic epithelial cells (mTECs) and dendritic cells, while TRP1 expression was restricted solely to mTECs. GILT facilitated MHC class II-restricted presentation of endogenous TRP1 by pooled thymic APCs. Using bone marrow chimeras, GILT expression in thymic epithelial cells (TECs), but not hematopoietic cells, was sufficient for complete deletion of TRP1-specific thymocytes. An increased frequency of TRP1-specific regulatory T (Treg) cells was present in chimeras with increased deletion of TRP1-specific thymocytes. Only chimeras that lacked GILT in both TECs and hematopoietic cells had a high conventional T:Treg cell ratio and were protected from melanoma challenge. Thus, GILT expression in thymic APCs, and mTECs in particular, preferentially facilitates MHC class II-restricted presentation, negative selection and increased Treg cells, resulting in a diminished anti-tumor response to a tissue-restricted, melanoma-associated self antigen.
• Ma, X., & Qiu, S. (2020). Control of cortical synapse development and plasticity by MET receptor tyrosine kinase, a genetic risk factor for autism. Journal of neuroscience research, 98(11), 2115-2129.
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  The key developmental milestone events of the human brain, such as neurogenesis, synapse formation, maturation, and plasticity, are determined by a myriad of molecular signaling events, including those mediated by a number of receptor tyrosine kinases (RTKs) and their cognate ligands. Aberrant or mistimed brain development and plasticity can lead to maladaptive changes, such as dysregulated synaptic connectivity and breakdown of circuit functions necessary for cognition and adaptive behaviors, which are hypothesized pathophysiologies of many neurodevelopmental and neuropsychiatric disorders. Here we review recent literature that supports autism spectrum disorder as a likely result of aberrant synapse development due to mistimed maturation and plasticity. We focus on MET RTK, a prominent genetic risk factor for autism, and discuss how a pleiotropic molecular signaling system engaged by MET exemplifies a genetic program that controls cortical circuit development and plasticity by modulating the anatomical and functional connectivity of cortical circuits, thus conferring genetic risk for neurodevelopmental disorders.
• Ma, X., Chen, K., Cui, Y., Huang, G., Nehme, A., Zhang, L., Li, H., Wei, J., Liong, K., Liu, Q., Shi, L., Wu, J., & Qiu, S. (2020). Depletion of microglia in developing cortical circuits reveals its critical role in glutamatergic synapse development, functional connectivity, and critical period plasticity. Journal of neuroscience research, 98(10), 1968-1986.
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  Microglia populate the early developing brain and mediate pruning of the central synapses. Yet, little is known on their functional significance in shaping the developing cortical circuits. We hypothesize that the developing cortical circuits require microglia for proper circuit maturation and connectivity, and as such, ablation of microglia during the cortical critical period may result in a long-lasting circuit abnormality. We administered PLX3397, a colony-stimulating factor 1 receptor inhibitor, to mice starting at postnatal day 14 and through P28, which depletes >75% of microglia in the visual cortex (VC). This treatment largely covers the critical period (P19-32) of VC maturation and plasticity. Patch clamp recording in VC layer 2/3 (L2/3) and L5 neurons revealed increased mEPSC frequency and reduced amplitude, and decreased AMPA/NMDA current ratio, indicative of altered synapse maturation. Increased spine density was observed in these neurons, potentially reflecting impaired synapse pruning. In addition, VC intracortical circuit functional connectivity, assessed by laser scanning photostimulation combined with glutamate uncaging, was dramatically altered. Using two photon longitudinal dendritic spine imaging, we confirmed that spine elimination/pruning was diminished during VC critical period when microglia were depleted. Reduced spine pruning thus may account for increased spine density and disrupted connectivity of VC circuits. Lastly, using single-unit recording combined with monocular deprivation, we found that ocular dominance plasticity in the VC was obliterated during the critical period as a result of microglia depletion. These data establish a critical role of microglia in developmental cortical synapse pruning, maturation, functional connectivity, and critical period plasticity.
• Qiu, S., Wu, J., Wei, J., Ma, X., Chen, K., Cui, Y., Huang, G., Nehme, A., Zhang, L., Li, H., Liong, K., Liu, Q., & Shi, L. (2020). Depletion of microglia in developing cortical circuits reveals its critical role in glutamatergic synapse development, functional connectivity, and critical period plasticity. Journal of Neuroscience Research, 98(10), 1968-1986. doi:10.1002/jnr.24641
• Rausch, M. P., Meador, L. R., Metzger, T. C., Li, H., Qiu, S., Anderson, M. S., & Hastings, K. T. (2020). GILT in Thymic Epithelial Cells Facilitates Central CD4 T Cell Tolerance to a Tissue-Restricted, Melanoma-Associated Self-Antigen. Journal of immunology (Baltimore, Md. : 1950), 204(11), 2877-2886.
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  Central tolerance prevents autoimmunity, but also limits T cell responses to potentially immunodominant tumor epitopes with limited expression in healthy tissues. In peripheral APCs, γ-IFN-inducible lysosomal thiol reductase (GILT) is critical for MHC class II-restricted presentation of disulfide bond-containing proteins, including the self-antigen and melanoma Ag tyrosinase-related protein 1 (TRP1). The role of GILT in thymic Ag processing and generation of central tolerance has not been investigated. We found that GILT enhanced the negative selection of TRP1-specific thymocytes in mice. GILT expression was enriched in thymic APCs capable of mediating deletion, namely medullary thymic epithelial cells (mTECs) and dendritic cells, whereas TRP1 expression was restricted solely to mTECs. GILT facilitated MHC class II-restricted presentation of endogenous TRP1 by pooled thymic APCs. Using bone marrow chimeras, GILT expression in thymic epithelial cells (TECs), but not hematopoietic cells, was sufficient for complete deletion of TRP1-specific thymocytes. An increased frequency of TRP1-specific regulatory T (Treg) cells was present in chimeras with increased deletion of TRP1-specific thymocytes. Only chimeras that lacked GILT in both TECs and hematopoietic cells had a high conventional T/Treg cell ratio and were protected from melanoma challenge. Thus, GILT expression in thymic APCs, and mTECs in particular, preferentially facilitates MHC class II-restricted presentation, negative selection, and increased Treg cells, resulting in a diminished antitumor response to a tissue-restricted, melanoma-associated self-antigen.
• Lawton, M. T., Shi, K., Shi, E., Sheth, K. N., Qiu, S., Lawton, M. T., & Ducruet, A. F. (2019). Chronic inflammation, cognitive impairment, and distal brain region alteration following intracerebral hemorrhage.. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 33(8), 9616-9626. doi:10.1096/fj.201900257r
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  Delayed cognitive decline commonly occurs following intracerebral hemorrhage (ICH), but the mechanisms underlying this phenomenon remain obscure. We therefore investigated the potential mechanisms responsible for impaired cognitive function in a mouse collagenase model of ICH. Following recovery of motor and sensory deficits in the chronic phase of ICH, we noted significant cognitive impairment, which was assessed by the Morris water maze. This finding was accompanied by reduced dendrite spine density of ipsilateral hippocampal CA1 neurons. Reduced synaptic plasticity, manifested by impaired long-term potentiation in hippocampal neurons, was also evident in both ipsilateral and contralateral hemispheres, suggesting that ICH also induces functional alterations in distal brain regions remote from the site of injury. In addition, the accumulation of microglia, infiltration of peripheral immune cells, and generation of reactive oxygen species were observed in both contralateral and ipsilateral hemispheres up to 5 wk post-ICH. Furthermore, depletion of microglia using PLX3397, which inhibits colony stimulating factor 1 receptor, ameliorated this delayed cognitive impairment. Collectively, these results suggest that persistent and diffuse brain inflammation may contribute to cognitive impairment in the chronic stage of ICH recovery.-Shi, E., Shi, K., Qiu, S., Sheth, K. N., Lawton, M. T., Ducruet, A. F. Chronic inflammation, cognitive impairment, and distal brain region alteration following intracerebral hemorrhage.
• Ma, Z., Gao, F., Larsen, B., Gao, M., Luo, Z., Chen, D., Ma, X., Qiu, S., Zhou, Y., Xie, J., Xi, Z., & Wu, J. (2019). Mechanisms of Cannabinoid CB2 Receptor-Mediated Reduction of Dopamine Neuronal Excitability in Mouse Ventral Tegmental Area. EBioMedicine. doi:10.2139/ssrn.3314420
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  We have recently reported that activation of cannabinoid type 2 receptors (CB2Rs) reduces dopamine (DA) neuron excitability in mouse ventral tegmental area (VTA). Here, we elucidate the underlying mechanisms. Using cell-attached recording in VTA slices, bath-application of CB2R agonists (JWH133 or five other CB2R agonists) significantly reduced VTA DA neuron action potential (AP) firing rate. Under patch-clamp whole-cell recording model, JWH133 (10 µM) mildly reduced the frequency of miniature excitatory postsynaptic currents (mEPSCs) but not miniature inhibitory postsynaptic currents (mIPSCs). JWH133 also did not alter evoked EPSCs or IPSCs. In freshly dissociated VTA DA neurons, JWH133 reduced AP firing rate, delayed AP initiation and enhanced AP after-hyperpolarization. In voltage-clamp recordings, JWH133 enhanced M-type K+ currents and this effect was absent in CB2-/- mice and abolished by co-administration of a selective CB2R antagonist (AM630). CB2R-mediated inhibition in VTA DA neuron firing can be mimicked by M-current opener and blocked by M-current blocker. In addition, enhancement of neuronal cAMP by forskolin reduced M-current and increased DA neuron firing rate. Finally, pharmacological block of synaptic transmission by NBQX, D-APV and picrotoxin in VTA slices failed to prevent CB2R-mediated inhibition, while intracellular infusion of guanosine 5'-O-2-thiodiphosphate (GDP-β-S) through recording electrode to block postsynaptic G-protein function prevented JWH133-induced reduction in AP firing. Collectively, our results suggest that CB2Rs modulate VTA DA neuron excitability mainly through an intrinsic mechanism, including a CB2R-mediated reduction of intracellular cAMP, and in turn enhancement of M-type K+ currents. Funding Statement: This research was supported by the Barrow Neuroscience Foundation, the BNI-BMS Seed Fund, the CNSF (81771437), and the National Institute on Drug Abuse, Intramural Research Program. Declaration of Interests: Dr. Ma, ZG reports no disclosures, Dr. Gao, FF reports no disclosures, Dr. Larsen, B. reports no disclosures, Dr. Gao M reports no disclosures, D. Chen, DJ reports no disclosures, Xiaokuang Ma reports no disclosures, Dr. Qiu, SF reports no disclosures, Dr. Zhou Y reports no disclosures, Dr. Xie, JX reports no disclosures, Dr. Xi, ZX reports no disclosures, Dr. Wu J reports no disclosures. Ethics Approval Statement: All experimental procedures were approved by the Institutional Animal Care and Use Committee at the Barrow Neurological Institute.
• Qiu, S., & Ma, X. (2019). Control of cortical synapse development and plasticity by MET receptor tyrosine kinase, a genetic risk factor for autism. Journal of Neuroscience Research, 98(11), 2115-2129. doi:10.1002/jnr.24542
• Wu, J., Qiu, S., Piechowicz, M., Ma, X., Lu, Z., Liu, Q., & Chen, K. (2019). Disruption of MET Receptor Tyrosine Kinase, an Autism Risk Factor, Impairs Developmental Synaptic Plasticity in the Hippocampus.. Developmental neurobiology, 79(1), 36-50. doi:10.1002/dneu.22645
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  As more genes conferring risks to neurodevelopmental disorders are identified, translating these genetic risk factors into biological mechanisms that impact the trajectory of the developing brain is a critical next step. Here, we report that disrupted signaling mediated MET receptor tyrosine kinase (RTK), an established risk factor for autism spectrum disorders, in the developing hippocampus glutamatergic circuit leads to profound deficits in neural development, synaptic transmission, and plasticity. In cultured hippocampus slices prepared from neonatal mice, pharmacological inhibition of MET kinase activity suppresses dendritic arborization and disrupts normal dendritic spine development. In addition, single-neuron knockdown (RNAi) or overexpression of Met in the developing hippocampal CA1 neurons leads to alterations, opposite in nature, in basal synaptic transmission and long-term plasticity. In forebrain-specific Met conditional knockout mice (Metfx/fx ;emx1cre ), an enhanced long-term potentiation (LTP) and long-term depression (LTD) were observed at early developmental stages (P12-14) at the Schaffer collateral to CA1 synapses compared with wild-type littermates. In contrast, LTP and LTD were markedly reduced at young adult stage (P56-70) during which wild-type mice show robust LTP and LTD. The altered trajectory of synaptic plasticity revealed by this study indicate that temporally regulated MET signaling as an intrinsic, cell autonomous, and pleiotropic mechanism not only critical for neuronal growth and functional maturation, but also for the timing of synaptic plasticity during forebrain glutamatergic circuits development.
• Zhou, L., Zheng, J., Yu, J., Xu, Z., Wang, K., Torshizi, A. D., Shi, L., Qiu, S., Ma, X., Huang, G., Gong, S., Chen, X., Chen, S., & Chen, Q. (2019). Uncovering the Functional Link Between SHANK3 Deletions and Deficiency in Neurodevelopment Using iPSC-Derived Human Neurons.. Frontiers in neuroanatomy, 13, 23. doi:10.3389/fnana.2019.00023
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  SHANK3 mutations, including de novo deletions, have been associated with autism spectrum disorders (ASD). However, the effects of SHANK3 loss of function on neurodevelopment remain poorly understood. Here we generated human induced pluripotent stem cells (iPSC) in vitro, followed by neuro-differentiation and lentivirus-mediated shRNA expression to evaluate how SHANK3 knockdown affects the in vitro neurodevelopmental process at multiple time points (up to 4 weeks). We found that SHANK3 knockdown impaired both early stage of neuronal development and mature neuronal function, as demonstrated by a reduction in neuronal soma size, growth cone area, neurite length and branch numbers. Notably, electrophysiology analyses showed defects in excitatory and inhibitory synaptic transmission. Furthermore, transcriptome analyses revealed that multiple biological pathways related to neuron projection, motility and regulation of neurogenesis were disrupted in cells with SHANK3 knockdown. In conclusion, utilizing a human iPSC-based neural induction model, this study presented combined morphological, electrophysiological and transcription evidence that support that SHANK3 as an intrinsic, cell autonomous factor that controls cellular function development in human neurons.
• Zhou, X., Shi, F. D., Qiu, S., Ma, X., Liu, Q., Li, Y. J., Li, H., & Gonzales, R. J. (2019). The selective sphingosine 1-phosphate receptor 1 modulator RP101075 improves microvascular circulation after cerebrovascular thrombosis.. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 33(10), 10935-10941. doi:10.1096/fj.201900282r
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  Sphingosine-1-phosphate receptor (S1PR) modulators provide protection in preclinical and clinical studies for ischemic stroke, but the influences of S1PR modulation on microvascular thrombosis remain poorly understood. This study investigates the impact of a selective S1PR1 modulator RP101075 on microvascular circulation in a mouse model of laser-induced thrombosis. The flow velocity of cortical arterioles in mice was measured in vivo under 2-photon laser scanning microscopy. Thrombosis was induced in cortical arterioles by laser irritation. At 30 min after laser-induced thrombosis, mice were treated with either RP101075 or vehicle. RP101075 did not alter the flow velocity of cortical arterioles under physiologic conditions. Laser-induced thrombosis led to a pronounced reduction of flow velocity in cortical arterioles that persisted for ≥90 min. The reduction of flow velocity in cortical arterioles following thrombosis was significantly attenuated following RP101075 treatment. RP101075 did not significantly affect coagulation time, bleeding time, heart rate, and blood pressure. In addition, RP101075 treatment reduced thrombus volume, which was accompanied by a reduction of leukocyte content in the thrombus. Our findings demonstrate that the selective S1PR1 modulator RP101075 improves microvascular circulation after thrombosis, implying a component of improved microvascular circulation to the benefit of S1PR modulation in cerebral ischemia.-Li, H., Zhou, X., Li, Y., Ma, X., Gonzales, R. J., Qiu, S., Shi, F.-D., Liu, Q. The selective sphingosine 1-phosphate receptor 1 modulator RP101075 improves microvascular circulation after cerebrovascular thrombosis.
• Zhou, Y., Xie, J., Xi, Z., Wu, J., Qiu, S., Ma, Z., Ma, X., Luo, Z., Larsen, B., Gao, M., Gao, F., & Chen, D. (2019). Mechanisms of cannabinoid CB2 receptor-mediated reduction of dopamine neuronal excitability in mouse ventral tegmental area.. EBioMedicine, 42, 225-237. doi:10.1016/j.ebiom.2019.03.040
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  We have recently reported that activation of cannabinoid type 2 receptors (CB2Rs) reduces dopamine (DA) neuron excitability in mouse ventral tegmental area (VTA). Here, we elucidate the underlying mechanisms..Patch-clamp recordings were performed in mouse VTA slices and dissociated single VTA DA neurons..Using cell-attached recording in VTA slices, bath-application of CB2R agonists (JWH133 or five other CB2R agonists) significantly reduced VTA DA neuron action potential (AP) firing rate. Under the patch-clamp whole-cell recording model, JWH133 (10 μM) mildly reduced the frequency of miniature excitatory postsynaptic currents (mEPSCs) but not miniature inhibitory postsynaptic currents (mIPSCs). JWH133 also did not alter evoked EPSCs or IPSCs. In freshly dissociated VTA DA neurons, JWH133 reduced AP firing rate, delayed AP initiation and enhanced AP after-hyperpolarization. In voltage-clamp recordings, JWH133 (1 μM) enhanced M-type K+ currents and this effect was absent in CB2-/- mice and abolished by co-administration of a selective CB2R antagonist (10 μM, AM630). CB2R-mediated inhibition in VTA DA neuron firing can be mimicked by M-current opener (10 μM retigabine) and blocked by M-current blocker (30 μM XE991). In addition, enhancement of neuronal cAMP by forskolin (10 μM) reduced M-current and increased DA neuron firing rate. Finally, pharmacological block of synaptic transmission by NBQX (10 μM), D-APV (50 μM) and picrotoxin (100 μM) in VTA slices failed to prevent CB2R-mediated inhibition, while intracellular infusion of guanosine 5'-O-2-thiodiphosphate (600 μM, GDP-β-S) through recording electrode to block postsynaptic G-protein function prevented JWH133-induced reduction in AP firing..Our results suggest that CB2Rs modulate VTA DA neuron excitability mainly through an intrinsic mechanism, including a CB2R-mediated reduction of intracellular cAMP, and in turn enhancement of M-type K+ currents. FUND: This research was supported by the Barrow Neuroscience Foundation, the BNI-BMS Seed Fund, and CNSF (81771437).
• Ma, X., Chen, K., Lu, Z., Piechowicz, M., Liu, Q., Wu, J., & Qiu, S. (2018). Disruption of MET Receptor Tyrosine Kinase, an Autism Risk Factor, Impairs Developmental Synaptic Plasticity in the Hippocampus. Developmental neurobiology.
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  As more genes conferring risks to neurodevelopmental disorders are identified, translating these genetic risk factors into biological mechanisms that impact the trajectory of the developing brain is a critical next step. Here, we report that disrupted signaling mediated MET receptor tyrosine kinase (RTK), an established risk factor for autism spectrum disorders, in the developing hippocampus glutamatergic circuit leads to profound deficits in neural development, synaptic transmission, and plasticity. In cultured hippocampus slices prepared from neonatal mice, pharmacological inhibition of MET kinase activity suppresses dendritic arborization and disrupts normal dendritic spine development. In addition, single-neuron knockdown (RNAi) or overexpression of Met in the developing hippocampal CA1 neurons leads to alterations, opposite in nature, in basal synaptic transmission and long-term plasticity. In forebrain-specific Met conditional knockout mice (Met ;emx1 ), an enhanced long-term potentiation (LTP) and long-term depression (LTD) were observed at early developmental stages (P12-14) at the Schaffer collateral to CA1 synapses compared with wild-type littermates. In contrast, LTP and LTD were markedly reduced at young adult stage (P56-70) during which wild-type mice show robust LTP and LTD. The altered trajectory of synaptic plasticity revealed by this study indicate that temporally regulated MET signaling as an intrinsic, cell autonomous, and pleiotropic mechanism not only critical for neuronal growth and functional maturation, but also for the timing of synaptic plasticity during forebrain glutamatergic circuits development.
• Qiu, S., Yang, X., Ren, H., Wood, K., Li, M., Shi, F., Ma, C., & Liu, Q. (2018). Depletion of microglia augments the dopaminergic neurotoxicity of MPTP. The FASEB Journal, 32(6), 3336-3345. doi:10.1096/fj.201700833rr
• Stephany, C., Ma, X., Dorton, H. M., Wu, J., Solomon, A. M., Frantz, M. G., Qiu, S., & McGee, A. W. (2018). Distinct Circuits for Recovery of Eye Dominance and Acuity in Murine Amblyopia. Current biology : CB, 28(12), 1914-1923.e5.
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  Degrading vision by one eye during a developmental critical period yields enduring deficits in both eye dominance and visual acuity. A predominant model is that "reactivating" ocular dominance (OD) plasticity after the critical period is required to improve acuity in amblyopic adults. However, here we demonstrate that plasticity of eye dominance and acuity are independent and restricted by the nogo-66 receptor (ngr1) in distinct neuronal populations. Ngr1 mutant mice display greater excitatory synaptic input onto both inhibitory and excitatory neurons with restoration of normal vision. Deleting ngr1 in excitatory cortical neurons permits recovery of eye dominance but not acuity. Reciprocally, deleting ngr1 in thalamus is insufficient to rectify eye dominance but yields improvement of acuity to normal. Abolishing ngr1 expression in adult mice also promotes recovery of acuity. Together, these findings challenge the notion that mechanisms for OD plasticity contribute to the alterations in circuitry that restore acuity in amblyopia.
• Yang, X., Ren, H., Wood, K., Li, M., Qiu, S., Shi, F. D., Ma, C., & Liu, Q. (2018). Depletion of microglia augments the dopaminergic neurotoxicity of MPTP. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 32(6), 3336-3345.
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  The activation of microglia and the various substances they produce have been linked to the pathologic development of Parkinson's disease (PD), but the precise role of microglia in PD remains to be defined. The survival of microglia depends on colony-stimulating factor 1 receptor (CSF1R) signaling, and CSF1R inhibition results in rapid elimination of microglia in the central nervous system. Using a mouse PD model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment, we showed that the depletion of microglia via the CSF1R inhibitor PLX3397 exacerbated the impairment of locomotor activities and the loss of dopaminergic neurons. Further, depletion of microglia augmented the production of inflammatory mediators and infiltration of leukocytes in the brain after MPTP exposure. Microglia depletion-induced aggravation of MPTP neurotoxicity was also seen in lymphocyte-deficient mice. In addition, the depletion of microglia did not affect the production of brain-derived neurotrophic factor, but it dramatically augmented the production of inflammatory mediators by astrocytes after MPTP treatment. Our findings suggest microglia play a protective role against MPTP-induced neuroinflammation and dopaminergic neurotoxicity.-Yang, X., Ren, H., Wood, K., Li, M., Qiu, S., Shi, F.-D., Ma, C., Liu, Q. Depletion of microglia augments the dopaminergic neurotoxicity of MPTP.
• Wu, J., Yin, J. X., Sun, G. Z., Shi, J., Qiu, S., Ma, X. K., Li, S. T., He, Y. C., Gao, M., & Chen, D. J. (2017). Hippocampal synaptic and neural network deficits in young mice carrying the human APOE4 gene.. CNS neuroscience & therapeutics, 23(9), 748-758. doi:10.1111/cns.12720
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  Apolipoprotein E4 (APOE4) is a major genetic risk factor for late-onset sporadic Alzheimer disease. Emerging evidence demonstrates a hippocampus-associated learning and memory deficit in aged APOE4 human carriers and also in aged mice carrying human APOE4 gene. This suggests that either exogenous APOE4 or endogenous APOE4 alters the cognitive profile and hippocampal structure and function. However, little is known regarding how Apoe4 modulates hippocampal dendritic morphology, synaptic function, and neural network activity in young mice..In this study, we compared hippocampal dendritic and spine morphology and synaptic function of young (4 months) mice with transgenic expression of the human APOE4 and APOE3 genes..Hippocampal dendritic and spine morphology and synaptic function were assessed by neuronal imaging and electrophysiological approaches..Morphology results showed that shortened dendritic length and reduced spine density occurred at hippocampal CA1 neurons in Apoe4 mice compared to Apoe3 mice. Electrophysiological results demonstrated that in the hippocampal CA3-CA1 synapses of young Apoe4 mice, basic synaptic transmission, and paired-pulse facilitation were enhanced but long-term potentiation and carbachol-induced hippocampal theta oscillations were impaired compared to young Apoe3 mice. However, both Apoe genotypes responded similarly to persistent stimulations (4, 10, and 40 Hz for 4 seconds)..Our results suggest significant alterations in hippocampal dendritic structure and synaptic function in Apoe4 mice, even at an early age.
• Lu, Z., Piechowicz, M., & Qiu, S. (2016). A Simplified Method for Ultra-Low Density, Long-Term Primary Hippocampal Neuron Culture. Journal of visualized experiments : JoVE.
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  Culturing primary hippocampal neurons in vitro facilitates mechanistic interrogation of many aspects of neuronal development. Dissociated embryonic hippocampal neurons can often grow successfully on glass coverslips at high density under serum-free conditions, but low density cultures typically require a supply of trophic factors by co-culturing them with a glia feeder layer, preparation of which can be time-consuming and laborious. In addition, the presence of glia may confound interpretation of results and preclude studies on neuron-specific mechanisms. Here, a simplified method is presented for ultra-low density (~2,000 neurons/cm2), long-term (>3 months) primary hippocampal neuron culture that is under serum free conditions and without glia cell support. Low density neurons are grown on poly-D-lysine coated coverslips, and flipped on high density neurons grown in a 24-well plate. Instead of using paraffin dots to create a space between the two neuronal layers, the experimenters can simply etch the plastic bottom of the well, on which the high density neurons reside, to create a microspace conducive to low density neuron growth. The co-culture can be easily maintained for >3 months without significant loss of low density neurons, thus facilitating the morphological and physiological study of these neurons. To illustrate this successful culture condition, data are provided to show profuse synapse formation in low density cells after prolonged culture. This co-culture system also facilitates the survival of sparse individual neurons grown in islands of poly-D-lysine substrates and thus the formation of autaptic connections.
• Peng, Y., Lu, Z., Li, G., Piechowicz, M., Anderson, M., Uddin, Y., Wu, J., & Qiu, S. (2016). The autism-associated MET receptor tyrosine kinase engages early neuronal growth mechanism and controls glutamatergic circuits development in the forebrain. Molecular psychiatry, 21(7), 925-35.
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  The human MET gene imparts a replicated risk for autism spectrum disorder (ASD), and is implicated in the structural and functional integrity of brain. MET encodes a receptor tyrosine kinase, MET, which has a pleiotropic role in embryogenesis and modifies a large number of neurodevelopmental events. Very little is known, however, on how MET signaling engages distinct cellular events to collectively affect brain development in ASD-relevant disease domains. Here, we show that MET protein expression is dynamically regulated and compartmentalized in developing neurons. MET is heavily expressed in neuronal growth cones at early developmental stages and its activation engages small GTPase Cdc42 to promote neuronal growth, dendritic arborization and spine formation. Genetic ablation of MET signaling in mouse dorsal pallium leads to altered neuronal morphology indicative of early functional maturation. In contrast, prolonged activation of MET represses the formation and functional maturation of glutamatergic synapses. Moreover, manipulating MET signaling levels in vivo in the developing prefrontal projection neurons disrupts the local circuit connectivity made onto these neurons. Therefore, normal time-delimited MET signaling is critical in regulating the timing of neuronal growth, glutamatergic synapse maturation and cortical circuit function. Dysregulated MET signaling may lead to pathological changes in forebrain maturation and connectivity, and thus contribute to the emergence of neurological symptoms associated with ASD.
• Wu, J., Gao, M., Rice, S. G., Tsang, C., Beggs, J., Turner, D., Li, G., Yang, B., Xia, K., Gao, F., Qiu, S., Liu, Q., & Kerrigan, J. F. (2016). Gap Junctions Contribute to Ictal/Interictal Genesis in Human Hypothalamic Hamartomas. EBioMedicine, 8, 96-102.
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  Human hypothalamic hamartoma (HH) is a rare subcortical lesion associated with treatment-resistant epilepsy. Cellular mechanisms responsible for epileptogenesis are unknown. We hypothesized that neuronal gap junctions contribute to epileptogenesis through synchronous activity within the neuron networks in HH tissue. We studied surgically resected HH tissue with Western-blot analysis, immunohistochemistry, electron microscopy, biocytin microinjection of recorded HH neurons, and microelectrode patch clamp recordings with and without pharmacological blockade of gap junctions. Normal human hypothalamus tissue was used as a control. Western blots showed increased expression of both connexin-36 (Cx36) and connexin-43 (Cx43) in HH tissue compared with normal human mammillary body tissue. Immunohistochemistry demonstrated that Cx36 and Cx43 are expressed in HH tissue, but Cx36 was mainly expressed within neuron clusters while Cx43 was mainly expressed outside of neuron clusters. Gap-junction profiles were observed between small HH neurons with electron microscopy. Biocytin injection into single recorded small HH neurons showed labeling of adjacent neurons, which was not observed in the presence of a neuronal gap-junction blocker, mefloquine. Microelectrode field recordings from freshly resected HH slices demonstrated spontaneous ictal/interictal-like discharges in most slices. Bath-application of gap-junction blockers significantly reduced ictal/interictal-like discharges in a concentration-dependent manner, while not affecting the action-potential firing of small gamma-aminobutyric acid (GABA) neurons observed with whole-cell patch-clamp recordings from the same patient's HH tissue. These results suggest that neuronal gap junctions between small GABAergic HH neurons participate in the genesis of epileptic-like discharges. Blockade of gap junctions may be a new therapeutic strategy for controlling seizure activity in HH patients.
• Qiu, S. -., & wu, j. (2015). Mechanisms of intrinsic epileptogenesis in human gelastic seizures with hypothalamic hamartoma.. CNS Neurosci Ther, 2, 104-11.
• Li, G., & Qiu, S. (2014). Neurodevelopmental Underpinnings of Angelman Syndrome. Journal of bioanalysis & biomedicine, 6(6), 052056.
• McGee, A., Li, G., Lu, Z., & Qiu, S. (2014). Convergent synaptic and circuit substrates underlying autism genetic risks. Frontiers in biology, 9(2), 137-150.
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  There has been a surge of diagnosis of autism spectrum disorders (ASD) over the past decade. While large, high powered genome screening studies of children with ASD have identified numerous genetic risk factors, research efforts to understanding how each of these risk factors contributes to the development autism has met with limited success. Revealing the mechanisms by which these genetic risk factors affect brain development and predispose a child to autism requires mechanistic understanding of the neurobiological changes underlying this devastating group of developmental disorders at multifaceted molecular, cellular and system levels. It has been increasingly clear that the normal trajectory of neurodevelopment is compromised in autism, in multiple domains as much as aberrant neuronal production, growth, functional maturation, patterned connectivity, and balanced excitation and inhibition of brain networks. Many autism risk factors identified in humans have been now reconstituted in experimental mouse models to allow mechanistic interrogation of the biological role of the risk gene. Studies utilizing these mouse models have revealed that underlying the enormous heterogeneity of perturbed cellular events, mechanisms directing synaptic and circuit assembly may provide a unifying explanation for the pathophysiological changes and behavioral endophenotypes seen in autism, although synaptic perturbations are far from being the only alterations relevant for ASD. In this review, we discuss synaptic and circuit abnormalities obtained from several prevalent mouse models, particularly those reflecting syndromic forms of ASD that are caused by single gene perturbations. These compiled results reveal that ASD risk genes contribute to proper signaling of the developing gene networks that maintain synaptic and circuit homeostasis, which is fundamental to normal brain development.
• Qiu, S. -. (2014). Convergent synaptic and circuit substrates underlying autism genetic risks.. Front Biol (Beijing), 9(2), 137-150.
• Qiu, S., Lu, Z., & Levitt, P. (2014). MET receptor tyrosine kinase controls dendritic complexity, spine morphogenesis, and glutamatergic synapse maturation in the hippocampus. The Journal of neuroscience : the official journal of the Society for Neuroscience, 34(49), 16166-79.
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  The MET receptor tyrosine kinase (RTK), implicated in risk for autism spectrum disorder (ASD) and in functional and structural circuit integrity in humans, is a temporally and spatially regulated receptor enriched in dorsal pallial-derived structures during mouse forebrain development. Here we report that loss or gain of function of MET in vitro or in vivo leads to changes, opposite in nature, in dendritic complexity, spine morphogenesis, and the timing of glutamatergic synapse maturation onto hippocampus CA1 neurons. Consistent with the morphological and biochemical changes, deletion of Met in mutant mice results in precocious maturation of excitatory synapse, as indicated by a reduction of the proportion of silent synapses, a faster GluN2A subunit switch, and an enhanced acquisition of AMPA receptors at synaptic sites. Thus, MET-mediated signaling appears to serve as a mechanism for controlling the timing of neuronal growth and functional maturation. These studies suggest that mistimed maturation of glutamatergic synapses leads to the aberrant neural circuits that may be associated with ASD risk.
• Stephany, C. É., Chan, L. L., Parivash, S. N., Dorton, H. M., Piechowicz, M., Qiu, S., & McGee, A. W. (2014). Plasticity of binocularity and visual acuity are differentially limited by nogo receptor. The Journal of neuroscience : the official journal of the Society for Neuroscience, 34(35), 11631-40.
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  The closure of developmental critical periods consolidates neural circuitry but also limits recovery from early abnormal sensory experience. Degrading vision by one eye throughout a critical period both perturbs ocular dominance (OD) in primary visual cortex and impairs visual acuity permanently. Yet understanding how binocularity and visual acuity interrelate has proven elusive. Here we demonstrate the plasticity of binocularity and acuity are separable and differentially regulated by the neuronal nogo receptor 1 (NgR1). Mice lacking NgR1 display developmental OD plasticity as adults and their visual acuity spontaneously improves after prolonged monocular deprivation. Restricting deletion of NgR1 to either cortical interneurons or a subclass of parvalbumin (PV)-positive interneurons alters intralaminar synaptic connectivity in visual cortex and prevents closure of the critical period for OD plasticity. However, loss of NgR1 in PV neurons does not rescue deficits in acuity induced by chronic visual deprivation. Thus, NgR1 functions with PV interneurons to limit plasticity of binocularity, but its expression is required more extensively within brain circuitry to limit improvement of visual acuity following chronic deprivation.
• Aldinger, K. A., & Qiu, S. (2013). New mouse genetic model duplicates human 15q11-13 autistic phenotypes, or does it?. Disease models & mechanisms, 3(1-2).
• Peng, Y., Huentelman, M., Smith, C., & Qiu, S. (2013). MET Receptor Tyrosine Kinase as an Autism Genetic Risk Factor. International review of neurobiology, 113, 135-65.
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  In this chapter, we will briefly discuss recent literature on the role of MET receptor tyrosine kinase (RTK) in brain development and how perturbation of MET signaling may alter normal neurodevelopmental outcomes. Recent human genetic studies have established MET as a risk factor for autism, and the molecular and cellular underpinnings of this genetic risk are only beginning to emerge from obscurity. Unlike many autism risk genes that encode synaptic proteins, the spatial and temporal expression pattern of MET RTK indicates this signaling system is ideally situated to regulate neuronal growth, functional maturation, and establishment of functional brain circuits, particularly in those brain structures involved in higher levels of cognition, social skills, and executive functions.
• Qiu, S., & Currás-Collazo, M. C. (2013). Histopathological and molecular changes produced by hippocampal microinjection of domoic acid. Neurotoxicology and teratology, 28(3).
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  The phytoplankton-derived neurotoxin, domoic acid (DOM), frequently causes poisoning of marine animals and poses an increasing threat to public health through contamination of seafood. In this study, we used stereotactic microinjection technique to administer varying amounts of DOM into the hippocampal CA1 region in order to examine potential histopathological changes after injection of sub-lethal concentrations to CA1 pyramidal neurons. Gross anatomical abnormalities in CA1 were observed at above 10 microM DOM (3 pmol in 0.3 microl saline). At 1mM concentration, DOM produces both ipsilateral and contralateral neuronal cell death in CA1, CA3 as well as dentate gyrus subfields. Animal behavioral changes after microinjection were similar to those observed by previous studies through systemic DOM injection. Neuronal degeneration was paralleled by reduced glutamate receptor (NR1, GluR1 and GluR6/7) immunolabeling throughout the whole hippocampal formation. Pre-injection of the AMPA/KA receptor antagonist NBQX (10 microM, 0.3 microl) blocked 1mM DOM-induced neuronal degeneration as well as behavioral symptoms. At concentrations lower than 10 microM, no histopathological changes were observed microscopically, nor were the levels of immunostaining of NR1, GluR1, GluR6/7 different. However, increased immunolabeling of autophosphorylated calcium-calmodulin-dependent kinase II (CaMKII, p-Thr286) and phosphorylated cAMP response element binding protein (CREB, p-Ser133) were observed at 24 h post-injection, suggesting that altered intracellular signal transduction mediated by GluRs might be an adaptive cellular protective mechanism against DOM-induced neurotoxicity.
• Wang, K., Schroth, G. P., Qiu, S., Luo, S., Li, R., Levitt, P., Knowles, J. A., & Evgrafov, O. V. (2013). Erratum: Single-neuron RNA-Seq: technical feasibility and reproducibility. Frontiers in Genetics, 4. doi:10.3389/fgene.2013.00023
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  To the Editor: In our manuscript entitled “Single-neuron RNA-Seq: technical feasibility and reproducibility,” published online on July 6th, 2012, we have made a few serious mistakes which need to be corrected: We referenced several points and quoted statements from a recent study by Okaty et al., but we neither cited the paper nor placed quotation marks on the statements. The full citation should be “Okaty, B. W., Sugino, K., and Nelson, S. B. (2011). Cell type-specific transcriptomics in the brain. J. Neurosci. 31, 6939–6943.” We request to add a citation after “The analysis of each single-cell transcriptome consists of several independent steps” in the first paragraph of Results, as “The analysis of each single-cell transcriptome consists of several independent steps (Okray et al., 2011),” given that these points were previously raised by Okaty et al. We request to add a citation to the first paragraph of Introduction, as “studies of gene expression and function in the brain were restricted to a relatively small number of genes (Luo and Geschwind, 2001; Zhang et al., 2002; Okaty et al., 2011),” given that this points was recently reviewed in the Okaty et al., paper. More importantly, we have made a mistake in quoting sentence from Okray et al., without quotation or citation. We wish to change the following sentence: Moreover, gene expression may be regulated in opposing directions in different cell types, thereby appearing static in composite data. To Moreover, as previously discussed by Okaty et al., “gene expression may be regulated in opposing directions in different cell types, thereby appearing static in composite data (Okaty et al., 2011).” We apologize to the readers of Frontiers in Genetics and to the authors of the Okaty et al., manuscript, for our failure to correct these mistakes during the review process of our manuscript.
• Xi, G., Hu, P., Qu, C., Qiu, S., Tong, C., & Ying, Q. (2013). Induced neural stem cells generated from rat fibroblasts. Genomics, proteomics & bioinformatics, 11(5).
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  The generation of induced tissue-specific stem cells has been hampered by the lack of well-established methods for the maintenance of pure tissue-specific stem cells like the ones we have for embryonic stem (ES) cell cultures. Using a cocktail of cytokines and small molecules, we demonstrate that primitive neural stem (NS) cells derived from mouse ES cells and rat embryos can be maintained. Furthermore, using the same set of cytokines and small molecules, we show that induced NS (iNS) cells can be generated from rat fibroblasts by forced expression of the transcriptional factors Oct4, Sox2 and c-Myc. The generation and long-term maintenance of iNS cells could have wide and momentous implications.
• Qiu, S., Aldinger, K. A., & Levitt, P. (2012). Modeling of autism genetic variations in mice: focusing on synaptic and microcircuit dysfunctions. Developmental neuroscience, 34(2-3).
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  Autism spectrum disorders (ASD) are heterogeneous neurodevelopmental disorders that are characterized by deficits in social interaction, verbal and nonverbal communication, and restrictive interests and repetitive behaviors. While human genetic studies have revealed marked heritability in ASD, it has been challenging to translate this genetic risk into a biological mechanism that influences brain development relevant to the disorder phenotypes. This is partly due to the complex genetic architecture of ASD, which involves de novo gene mutations, genomic abnormalities, and common genetic variants. Rather than trying to reconstitute the clinical disorder, using genetic model animals to examine specific features of core ASD pathophysiology offers unique opportunities for refining our understanding of neurodevelopmental mechanisms in ASD. A variety of ASD-relevant phenotypes can now be investigated in rodents, including stereotyped and repetitive behaviors, and deficits in social interaction and communication. In this review, we focus on several prevailing mouse models and discuss how studies have advanced our understanding of synaptic mechanisms that may underlie ASD pathophysiology. Although synaptic perturbations are not the only alterations relevant for ASD, we reason that understanding the synaptic underpinnings of ASD using mouse models may provide mechanistic insights into its etiology and lead to novel therapeutic and interventional strategies.
• Qiu, S., Luo, S., Evgrafov, O., Li, R., Schroth, G. P., Levitt, P., Knowles, J. A., & Wang, K. (2012). Single-neuron RNA-Seq: technical feasibility and reproducibility. Frontiers in genetics, 3.
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  Understanding brain function involves improved knowledge about how the genome specifies such a large diversity of neuronal types. Transcriptome analysis of single neurons has been previously described using gene expression microarrays. Using high-throughput transcriptome sequencing (RNA-Seq), we have developed a method to perform single-neuron RNA-Seq. Following electrophysiology recording from an individual neuron, total RNA was extracted by aspirating the cellular contents into a fine glass electrode tip. The mRNAs were reverse transcribed and amplified to construct a single-neuron cDNA library, and subsequently subjected to high-throughput sequencing. This approach was applied to both individual neurons cultured from embryonic mouse hippocampus, as well as neocortical neurons from live brain slices. We found that the average pairwise Spearman's rank correlation coefficient of gene expression level expressed as RPKM (reads per kilobase of transcript per million mapped reads) was 0.51 between five cultured neuronal cells, whereas the same measure between three cortical layer 5 neurons in situ was 0.25. The data suggest that there may be greater heterogeneity of the cortical neurons, as compared to neurons in vitro. The results demonstrate the technical feasibility and reproducibility of RNA-Seq in capturing a part of the transcriptome landscape of single neurons, and confirmed that morphologically identical neurons, even from the same region, have distinct gene expression patterns.
• Aldinger, K. A., Plummer, J. T., Qiu, S., & Levitt, P. (2011). SnapShot: genetics of autism. Neuron, 72(2).
• Qiu, S., Anderson, C. T., Levitt, P., & Shepherd, G. M. (2011). Circuit-specific intracortical hyperconnectivity in mice with deletion of the autism-associated Met receptor tyrosine kinase. The Journal of neuroscience : the official journal of the Society for Neuroscience, 31(15).
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  Local hyperconnectivity in the neocortex is a hypothesized pathophysiological state in autism spectrum disorder (ASD). MET, a receptor tyrosine kinase that regulates dendrite and spine morphogenesis, has been established as a risk gene for ASD. Here, we analyzed the synaptic circuit organization of identified pyramidal neurons in the anterior frontal cortex of mice with a dorsal pallium-derived, conditional knock-out (cKO) of Met. Synaptic mapping by glutamate uncaging identified layer 2/3 as the main source of local excitatory input to layer 5 projection neurons in controls. In both cKO and heterozygotes, this pathway was stronger by a factor of approximately 2. This increase was both sublayer and projection-class specific, restricted to corticostriatal neurons in upper layer 5B and not neighboring corticopontine neurons. Paired recordings in cKO slices demonstrated increased unitary connectivity. We propose that excitatory hyperconnectivity in specific neocortical microcircuits constitutes a physiological basis for Met-mediated ASD risk.
• Qiu, S., & Aldinger, K. A. (2010). New mouse genetic model duplicates human 15q11-13 autistic phenotypes, or does it?. Disease models & mechanisms, 3(1-2), 3-4. doi:10.1242/dmm.004663
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  Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental disorders that manifest deficits in social interaction, and verbal and non-verbal communication, in addition to restrictive interests and repetitive behaviors. Recent reports indicate that ASDs may occur in as many as
• Qiu, S., Champagne, D. L., Peters, M., Catania, E. H., Weeber, E. J., Levitt, P., & Pimenta, A. F. (2010). Loss of limbic system-associated membrane protein leads to reduced hippocampal mineralocorticoid receptor expression, impaired synaptic plasticity, and spatial memory deficit. Biological psychiatry, 68(2).
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  The limbic system-associated membrane protein (LAMP) promotes development of neurons of limbic origin. We have previously shown that genetic deletion of LAMP results in heightened reactivity to novelty and reduced anxiety-like behaviors in mice. Here, we demonstrate a critical role of LAMP in hippocampal-dependent synaptic physiology and behavior.
• Qiu, S., Jebelli, A. K., Ashe, J. H., & Currás-Collazo, M. C. (2009). Domoic acid induces a long-lasting enhancement of CA1 field responses and impairs tetanus-induced long-term potentiation in rat hippocampal slices. Toxicological sciences : an official journal of the Society of Toxicology, 111(1).
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  Domoic acid (DOM) is known to cause hippocampal neuronal damage and produces amnesic effects. We examined synaptic plasticity changes induced by DOM exposure in rat hippocampal CA1 region. Brief bath application of DOM to hippocampal slices produces a chemical form of long-term potentiation (LTP) of CA1 field synaptic potentials. The potentiation cannot be blocked by NMDA receptor antagonist MK-801 but can be blocked by the calcium-calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-62 or cAMP-dependent protein kinase (PKA) inhibitor H-89. DOM-potentiated slices show decreased autophosphorylated CaMKII (p-Thr286), an effect that is also dependent on the activity of CaMKII and PKA. Increased phosphorylation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit GluR1 (p-Ser831) was seen in DOM-potentiated slices. Therefore, aberrant regulation of CaMKII and GluR1 phosphorylation occurs after DOM application. In addition, tetanus-induced LTP as well as the increase of phosphorylation of CaMKII (p-Thr286) were reduced in DOM-potentiated slices. Compared with brief exposure, slices recovering from prolonged exposure did not show potentiation or altered levels of CaMKII (p-Thr286) or GluR (p-Ser831). However, decreased phosphorylation of GluR1 at Ser845 was seen. These results describe a new chemical form of LTP and uncover novel molecular changes induced by DOM. The observed impairment of tetanus LTP and misregulation of CaMKII and GluR1 phosphorylation may partially account for DOM neurotoxicity and underlie the molecular basis for DOM-induced memory deficit.
• Fan, D., Yancey, P. G., Qiu, S., Ding, L., Weeber, E. J., Linton, M. F., & Fazio, S. (2008). Self-association of human PCSK9 correlates with its LDLR-degrading activity. Biochemistry, 47(6).
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  Genetic studies have demonstrated an important role for proprotein convertase subtilisin/kexin type 9 (PCSK9) as a determinant of plasma cholesterol levels. However, the underlying molecular mechanism is not completely understood. To this end, we have generated a mammalian cell expression system for human PCSK9 and its mutants and produced transgenic mice expressing human PCSK9. HEK293T cells transfected with the human PCSK9 DNA construct expressed and secreted PCSK9 and displayed decreased LDLR levels; functional PCSK9 protein was purified from the conditioned medium. In vitro studies showed that PCSK9 self-associated in a concentration-, temperature-, and pH-dependent manner. A mixture of PCSK9 monomers, dimers, and trimers displayed an enhanced LDLR degrading activity compared to monomeric PCSK9. A gain-of-function mutant, D374Y, displayed greatly increased self-association compared to wild-type PCSK9. Moreover, we demonstrated that the catalytic domain of PCSK9 is responsible for the self-association. Self-association of PCSK9 was enhanced by incubation with mouse apoE-/- VLDL and inhibited by incubation with both human and mouse HDL. When PCSK9 protein was incubated with total serum, it partially associated with LDL and HDL but not with VLDL. In transgenic mice, PCSK9 also associated with LDL and HDL but not with VLDL. We conclude that self-association is an intrinsic property of PCSK9, correlated to its LDLR-degrading activity and affected by plasma lipoproteins. These results provide a basis for developing strategies to manipulate PCSK9 activity in the circulation for the treatment of hypercholesterolemia.
• Levenson, J. M., Qiu, S., & Weeber, E. J. (2008). The role of reelin in adult synaptic function and the genetic and epigenetic regulation of the reelin gene. Biochimica et biophysica acta, 1779(8).
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  An emerging theme in the field of neuroscience is that processes critical for neurodevelopment have been co-opted by the adult nervous system to subserve synaptic plasticity and cognition. In this review, we highlight a surprising intersection of two developmental processes that together play a critical role in synaptic plasticity, memory formation and cognition. Reelin, a large glycoprotein associated with the extracellular matrix, is crucial for cortical and cerebellar development. Recent data from several groups indicate that reelin plays a unique modulatory role in the induction of synaptic plasticity in the hippocampus, and that normal levels of reelin in the adult brain are essential for successful formation of certain forms of long-term memory. Given that both increases and decreases in reelin expression have significant effects on plasticity and memory, regulation of reelin expression is predicted to have significant effects on neural function. Epigenetic regulation of transcription is critical for differentiation of cellular phenotype in metazoans. Dozens of reports in the last few years have demonstrated that epigenetics is involved in modulating gene expression in the adult nervous system and subserves plasticity and memory formation. We review a series of studies that demonstrate that the reelin promoter is subject to differential DNA methylation in the adult nervous system, and that perturbations in reelin promoter methylation correlate with alterations in memory formation and cognition. Thus, two distinct developmental processes, reelin-mediated signaling and epigenetic-based transcriptional regulation, appear to have synergized in the adult nervous system to create a sensitive and robust system for modulation of synaptic plasticity, and ultimately provide a powerful set of tools to probe the molecular basis of cognition.
• Tanner, D. C., Qiu, S., Bolognani, F., Partridge, L. D., Weeber, E. J., & Perrone-Bizzozero, N. I. (2008). Alterations in mossy fiber physiology and GAP-43 expression and function in transgenic mice overexpressing HuD. Hippocampus, 18(8).
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  HuD is a neuronal RNA-binding protein associated with the stabilization of mRNAs for GAP-43 and other neuronal proteins that are important for nervous system development and learning and memory mechanisms. To better understand the function of this protein, we generated transgenic mice expressing human HuD (HuD-Tg) in adult forebrain neurons. We have previously shown that expression of HuD in adult dentate granule cells results in an abnormal accumulation of GAP-43 mRNA via posttranscriptional mechanisms. Here we show that this mRNA accumulation leads to the ectopic expression of GAP-43 protein in mossy fibers. Electrophysiological analyses of the mossy fiber to CA3 synapse of HuD-Tg mice revealed increases in paired-pulse facilitation (PPF) at short interpulse intervals and no change in long-term potentiation (LTP). Presynaptic calcium transients at the same synapses exhibited faster time constants of decay, suggesting a decrease in the endogenous Ca(2+) buffer capacity of mossy fiber terminals of HuD-Tg mice. Under resting conditions, GAP-43 binds very tightly to calmodulin sequestering it and then releasing it upon PKC-dependent phosphorylation. Therefore, subsequent studies examined the extent of GAP-43 phosphorylation and its association to calmodulin. We found that despite the increased GAP-43 expression in HuD-Tg mice, the levels of PKC-phosphorylated GAP-43 were decreased in these animals. Furthermore, in agreement with the increased proportion of nonphosphorylated GAP-43, HuD-Tg mice showed increased binding of calmodulin to this protein. These results suggest that a significant amount of calmodulin may be trapped in an inactive state, unable to bind free calcium, and activate downstream signaling pathways. In conclusion, we propose that an unregulated expression of HuD disrupts mossy fiber physiology in adult mice in part by altering the expression and phosphorylation of GAP-43 and the amount of free calmodulin available at the synaptic terminal.
• Bolognani, F., Qiu, S., Tanner, D. C., Paik, J., Perrone-Bizzozero, N. I., & Weeber, E. J. (2007). Associative and spatial learning and memory deficits in transgenic mice overexpressing the RNA-binding protein HuD. Neurobiology of learning and memory, 87(4).
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  HuD is a neuronal specific RNA-binding protein associated with the stabilization of short-lived mRNAs during brain development, nerve regeneration and synaptic plasticity. To investigate the functional significance of this protein in the mature brain, we generated transgenic mice overexpressing HuD in forebrain neurons under the control of the alphaCaMKinII promoter. We have previously shown that one of the targets of HuD, GAP-43 mRNA, was stabilized in neurons in the hippocampus, amygdala and cortex of transgenic mice. Animals from two independent lines expressing different levels of the transgene were subjected to a battery of behavioral tests including contextual fear conditioning and the Morris water maze. Our results show that although HuD is increased after learning and memory, constitutive HuD overexpression impaired the acquisition and retention of both cued and contextual fear and the ability to remember the position of a hidden platform in the Morris water maze. No motor-sensory abnormalities were observed in HuD transgenic mice, suggesting that the poor performance of the mice in these tests reflect a true cognitive impairment. We conclude that posttranscriptional regulation of gene expression by stabilization of specific mRNAs may have to be restricted temporally and spatially for proper acquisition and storage of memories.
• Fan, D., Qiu, S., Overton, C. D., Yancey, P. G., Swift, L. L., Jerome, W. G., Linton, M. F., & Fazio, S. (2007). Impaired secretion of apolipoprotein E2 from macrophages. The Journal of biological chemistry, 282(18).
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  Human apoE is a multifunctional and polymorphic protein synthesized and secreted by liver, brain, and tissue macrophages. Here we show that apoE isoforms and mutants expressed through lentiviral transduction display cell-specific differences in secretion efficiency. Whereas apoE3, apoE4, and a natural mutant of apoE4 (apoE-Cys(142)) were efficiently secreted from macrophages, apoE2 and a non-natural apoE mutant (apoE-Cys(112)/Cys(142)) were retained in the perinuclear region and only minimally secreted. The secretory block for apoE2 in macrophages was not affected by the ablation of LDLR (low density lipoprotein receptor), ABCA-1, or SR-BI (scavenger receptor class B type I) but was released in the absence of low density lipoprotein receptor related protein (LRP). In co-immunoprecipitation experiments, an anti-apoE antibody pulled down two times more LRP in apoE2-transduced macrophages than in apoE3-expressing macrophages. Non-reducing SDS-PAGE/Western blot analyses showed that macrophage apoE2 is mostly dimeric and multimeric, whereas apoE3 is predominantly monomeric. ApoE2 retention and multimer formation also occurred in human macrophages derived from the monocyte cell line THP-1. These results were specific for macrophages, as in transduced mouse primary hepatocytes: 1) ApoE2 was secreted as efficiently as apoE3 and apoE4; 2) all isoforms were exclusively in monomeric form; 3) there was no co-immunoprecipitation of apoE and LRP. A microsomal triglyceride transfer protein (MTP) inhibitor nearly deleted apoB100 secretion from hepatocytes without affecting apoE secretion. These data show that macrophages retain apoE2, a highly expressed protein carried by about 8% of the human population. Given the role of locally produced apoE in regulating cholesterol efflux, modulating inflammation, and controlling oxidative stress, this unique property of apoE2 may have important impacts on atherogenesis.
• Qiu, S., & Weeber, E. J. (2007). Reelin signaling facilitates maturation of CA1 glutamatergic synapses. Journal of neurophysiology, 97(3).
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  Reelin signaling through the low-density lipoprotein receptor family members, apoliproprotein E receptor 2 (apoER2) and very-low-density lipoprotein receptor (VLDLR), plays a pivotal role in dictating neuronal lamination during embryonic brain development. Recent evidence suggests that this signaling system also plays a role in the postnatal brain to modulate synaptic transmission, plasticity, and cognitive behavior, mostly likely due to a functional coupling with N-methyl-d-aspartate (NMDA) receptors. In this study, we investigated the effects of reelin on the maturation of CA1 glutamatergic function using electrophysiological and biochemical approaches. In cultured hippocampal slices, reelin treatment increased the amplitude of AMPAR-mediated miniature excitatory postsynaptic currents and the evoked AMPA/NMDA receptor current ratios. In addition, reelin treatment also reduced the number of silent synapses, facilitated a developmental switch from NR2B to NR2A of NMDARs, and increased surface expression of AMPARs in CA1 tissue. In cultured hippocampal neurons from reeler embryos, reduced numbers of AMPAR subunit GluR1 and NMDAR subunit NR1 clustering were observed compared with those obtained from wild-type embryos. Supplementing reelin in the reeler culture obliterated these genotypic differences. These results demonstrate that reelin- and lipoprotein receptor-mediated signaling may operate during developmental maturation of hippocampal glutamatergic function and thus represent a potential important mechanism for controlling synaptic strength and plasticity in the postnatal hippocampus.
• Qiu, S., Li, L., Weeber, E. J., & May, J. M. (2007). Ascorbate transport by primary cultured neurons and its role in neuronal function and protection against excitotoxicity. Journal of neuroscience research, 85(5).
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  Neurons maintain relatively high intracellular concentrations of ascorbic acid, which is achieved primarily by the activity of the sodium-dependent vitamin C transporter SVCT2. In this work, we studied the mechanisms by which neuronal cells in culture transport and maintain ascorbate as well as whether this system contributes to maturation of neuronal function and cellular defense against oxidative stress and excitotoxic injury. We found that the SVCT2 helps to maintain high intracellular ascorbate levels, normal ascorbate transport kinetics, and activity-dependent ascorbate recycling. Immunocytochemistry studies revealed that SVCT2 is expressed primarily in the axons of mature hippocampal neurons in culture. In the absence of SVCT2, hippocampal neurons exhibited stunted neurite outgrowth, less glutamate receptor clustering, and reduced spontaneous neuronal activity. Finally, hippocampal cultures from SVCT2-deficient mice showed increased susceptibility to oxidative damage and N-methyl-D-aspartate-induced excitotoxicity. Our results revealed that maintenance of intracellular ascorbate as a result of SVCT2 activity is crucial for neuronal development, functional maturation, and antioxidant responses.
• van Woerden, G. M., Harris, K. D., Hojjati, M. R., Gustin, R. M., Qiu, S., de Avila Freire, R., Jiang, Y., Elgersma, Y., & Weeber, E. J. (2007). Rescue of neurological deficits in a mouse model for Angelman syndrome by reduction of alphaCaMKII inhibitory phosphorylation. Nature neuroscience, 10(3).
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  Angelman syndrome (AS) is a severe neurological disorder characterized by mental retardation, motor dysfunction and epilepsy. We show that the molecular and cellular deficits of an AS mouse model can be rescued by introducing an additional mutation at the inhibitory phosphorylation site of alphaCaMKII. Moreover, these double mutants no longer show the behavioral deficits seen in AS mice, suggesting that these deficits are the direct result of increased inhibitory phosphorylation of alphaCaMKII.
• Qiu, S., & Curras-collazo, M. C. (2006). Histopathological and molecular changes produced by hippocampal microinjection of domoic acid.. Neurotoxicology and teratology, 28(3), 354-62. doi:10.1016/j.ntt.2006.01.012
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  The phytoplankton-derived neurotoxin, domoic acid (DOM), frequently causes poisoning of marine animals and poses an increasing threat to public health through contamination of seafood. In this study, we used stereotactic microinjection technique to administer varying amounts of DOM into the hippocampal CA1 region in order to examine potential histopathological changes after injection of sub-lethal concentrations to CA1 pyramidal neurons. Gross anatomical abnormalities in CA1 were observed at above 10 microM DOM (3 pmol in 0.3 microl saline). At 1mM concentration, DOM produces both ipsilateral and contralateral neuronal cell death in CA1, CA3 as well as dentate gyrus subfields. Animal behavioral changes after microinjection were similar to those observed by previous studies through systemic DOM injection. Neuronal degeneration was paralleled by reduced glutamate receptor (NR1, GluR1 and GluR6/7) immunolabeling throughout the whole hippocampal formation. Pre-injection of the AMPA/KA receptor antagonist NBQX (10 microM, 0.3 microl) blocked 1mM DOM-induced neuronal degeneration as well as behavioral symptoms. At concentrations lower than 10 microM, no histopathological changes were observed microscopically, nor were the levels of immunostaining of NR1, GluR1, GluR6/7 different. However, increased immunolabeling of autophosphorylated calcium-calmodulin-dependent kinase II (CaMKII, p-Thr286) and phosphorylated cAMP response element binding protein (CREB, p-Ser133) were observed at 24 h post-injection, suggesting that altered intracellular signal transduction mediated by GluRs might be an adaptive cellular protective mechanism against DOM-induced neurotoxicity.
• Qiu, S., Korwek, K. M., & Weeber, E. J. (2006). A fresh look at an ancient receptor family: emerging roles for low density lipoprotein receptors in synaptic plasticity and memory formation. Neurobiology of learning and memory, 85(1).
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  The well-known family of low-density lipoprotein receptors represents a collection of ancient membrane receptors that have been remarkably conserved throughout evolution. These multifunctional receptors, known to regulate cholesterol transport, are becoming increasingly interesting to the neuroscience community due to their ability to transduce a diversity of extracellular signals across the membrane in the adult CNS. Their roles in modulating synaptic plasticity and necessity in hippocampus-specific learning and memory have recently come to light. In addition, genetic, biochemical and behavioral studies have implicated these signaling systems in a number of human neurodegenerative and neuropsychiatric disorders involving loss of cognitive ability, such as Alzheimer's disease, schizophrenia and autism. This review describes the known functions of these receptors and discusses their potential role in processes of synaptic regulation and memory formation.
• Qiu, S., Korwek, K. M., Pratt-Davis, A. R., Peters, M., Bergman, M. Y., & Weeber, E. J. (2006). Cognitive disruption and altered hippocampus synaptic function in Reelin haploinsufficient mice. Neurobiology of learning and memory, 85(3).
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  The heterozygote reeler mouse (HRM) shows many neuroanatomical and biochemical features that are also present in some human cognitive disorders, such as schizophrenia. In the present study, hippocampal dependent plasticity and cognitive function of the HRM were characterized in detail in an attempt to reveal phenotypic functional differences that result from Reelin haploinsufficiency. The HRM and wild type mice show similar levels of overall activity, coordination, thermal nociception, startle responses, and anxiety-like behavior. In addition, both genotypes show similar shock threshold, identical cued freezing behavior and comparable spatial learning in Morris water maze tasks. However, a significant reduction in contextual fear conditioned learning was observed in the HRM. Electrophysiological studies in hippocampal CA1 synapses revealed a plethora of differences between genotypes. The HRM exhibits reduced field excitatory postsynaptic potentials in responses to similar synaptic inputs, lowered paired pulse facilitation ratio and impaired long-term depression and tetanus-induced long-term potentiation (LTP). Also, deficits were detected in LTP elicited by theta burst stimulation or by a whole cell pairing protocol. These physiologic differences could not be accounted for by changes in the overall amount of glutamate receptor subunits. In addition, it was determined that network-driven excitatory and inhibitory activities recorded in CA1 pyramidal neurons showed that the HRM had comparable amplitude and frequency of spontaneous excitatory postsynaptic currents, but a marked reduction in spontaneous inhibitory postsynaptic currents. Thus, the HRM exhibits a specific hippocampal-dependent learning deficit accompanied with a pronounced impairment of hippocampal plasticity and functional inhibitory innervation.
• Qiu, S., Pak, C. W., & Currás-Collazo, M. C. (2006). Sequential involvement of distinct glutamate receptors in domoic acid-induced neurotoxicity in rat mixed cortical cultures: effect of multiple dose/duration paradigms, chronological age, and repeated exposure. Toxicological sciences : an official journal of the Society of Toxicology, 89(1).
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  The increasing occurrence of poisoning accidents in marine animals caused by the amnesic shellfish toxin, domoic acid (DOM), necessitates a better understanding of the factors contributing to DOM neurotoxicity. Here we evaluated the contribution and temporal involvement of NMDA, non-NMDA- and metabotropic-type glutamate receptors (GluRs) in DOM-induced neuronal death using rat primary mixed cortical cultures. Co-application of antagonists for AMPA/kainate- (NBQX) and NMDA-type GluRs (D-AP5) but not for metabotropic GluRs reduced DOM toxicity induced by either of three EC50 dose/duration exposure paradigms. Maximal protection offered by D-AP5 and NBQX either extended or not to the 30- to 60-min period after DOM exposure, respectively. Antagonists were ineffective if applied with a 2-h delay, indicating the presence of a critical time window for neuronal protection after DOM exposure. Early effects correlated with neuronal swelling was seen as early as 10 min post-DOM, which has been linked to non-NMDAR-mediated depolarization and release of endogenous glutamate. That DOM toxicity is dictated by iGluRs is supported by the finding that increased efficacy and potency of DOM with in vitro neuronal maturation are positively correlated with elevated protein levels of iGluR subunits, including NR1, GluR1, GluR2/3, GluR5, and GluR6/7. We determined the time course of DOM excitotoxicity. At >10 microM maximal neuronal death occurs within 2 h, while doses < or = 10 microM continue to produce death during the subsequent 22-h washout period, indicating a quicker progression of the neuronal death cascade with high DOM concentrations. Accordingly, NBQX applied 30 min post-DOM afforded better protection against low dose/prolonged duration (3 microM/24 h) than against high dose/brief duration exposure (50 microM/10 min). Interestingly, prior exposure to subthreshold DOM dose-dependently aggravated toxicity produced by a subsequent exposure to DOM. These findings provide greater insight into the complex properties underlying DOM toxicity, including the sequential involvement of multiple GluRs, greater potency with increasing neuronal maturation and protein levels of iGluRs, varying efficacy depending on dose, duration, and prior history of DOM exposure.
• Qiu, S., Zhao, L. F., Korwek, K. M., & Weeber, E. J. (2006). Differential reelin-induced enhancement of NMDA and AMPA receptor activity in the adult hippocampus. The Journal of neuroscience : the official journal of the Society for Neuroscience, 26(50).
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  The developmental lamination of the hippocampus and other cortical structures requires a signaling cascade initiated by reelin and its receptors, apoER2 (apolipoprotein E receptor 2) and VLDLR (very-low-density lipoprotein receptor). However, the functional significance of continued reelin expression in the postnatal brain remains poorly understood. Here, we show that reelin application to adult mice hippocampal slices leads to enhanced glutamatergic transmission mediated by NMDA receptors (NMDARs) and AMPA receptors (AMPARs) through distinct mechanisms. Application of recombinant reelin enhanced NMDAR-mediated currents through postsynaptic mechanisms, as revealed by the variance-mean analysis of synaptic NMDAR currents, assessment of spontaneous miniature events, and the levels of NMDAR subunits at synaptic surface. In comparison, nonstationary fluctuation analysis of miniature AMPAR currents and quantification of synaptic surface proteins revealed that reelin-induced enhancement of AMPAR responses was mediated by increased AMPAR numbers. Reelin enhancement of synaptic NMDAR currents was abolished when receptor-associated protein (RAP) or the Src inhibitor 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]-pyrimidine (PP1) was bath applied and was abrogated by including PP1 in the recording electrodes. In comparison, including RAP or an inactive PP1 analog PP3 in the recording electrode was without effect. Interestingly, the increased AMPAR response after reelin application was not blocked by PP1 but was blocked by the phosphoinositide-3' kinase (PI3K) inhibitors wortmannin and LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride]. Furthermore, reelin-induced, PI3K-dependent AMPAR surface insertion was also observed in cultured hippocampal neurons. Together, these results reveal a differential functional coupling of reelin signaling with NMDAR and AMPAR function and define a novel mechanism for controlling synaptic strength and plasticity in the adult hippocampus.
• Beffert, U., Weeber, E. J., Durudas, A., Qiu, S., Masiulis, I., Sweatt, J. D., Li, W., Adelmann, G., Frotscher, M., Hammer, R. E., & Herz, J. (2005). Modulation of synaptic plasticity and memory by Reelin involves differential splicing of the lipoprotein receptor Apoer2. Neuron, 47(4).
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  Apolipoprotein E receptor 2 (Apoer2), a member of the LDL receptor gene family, and its ligand Reelin control neuronal migration during brain development. Apoer2 is also essential for induction of long-term potentiation (LTP) in the adult brain. Here we show that Apoer2 is present in the postsynaptic densities of excitatory synapses where it forms a functional complex with NMDA receptors. Reelin signaling through Apoer2 markedly enhances LTP through a mechanism that requires the presence of amino acids encoded by an exon in the intracellular domain of Apoer2. This exon is alternatively spliced in an activity-dependent manner and is required for Reelin-induced tyrosine phosphorylation of NMDA receptor subunits. Mice constitutively lacking the exon perform poorly in learning and memory tasks. Thus, alternative splicing of Apoer2, a novel component of the NMDA receptor complex, controls the modulation of NMDA receptor activity, synaptic neurotransmission, and memory by Reelin.

Reviews

• Qiu, S., Xu, Y., Tu, W., & Xu, J. (2023. Molecular biomarkers in the prediction, diagnosis, and prognosis of neurodegenerative diseases..

Others

• Anderson, C. E., Qiu, S. -., Levitt, P., & Shepherd, G. G. (2010, Spring). Microcircuits of autism: electroanatomical analysis of frontal cortex circuits in mice with forebrain-specific loss of Met receptor tyrosine kinase.. Society for Neuroscience.
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  Program No. 562.3 Abstract Viewer/Itinerary Planner.
• Qiu, S. -., Anderson, C. E., Shepherd, G. G., & Levitt, P. (2010, Spring). Electrophysiological analysis of frontal cortex circuits in mice with forebrain-specific loss of Met receptor tyrosine kinase. Society for Neuroscience.
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  Program No. 562.10 Abstract Viewer/Itinerary Planner.
• Qiu, S. -., Korwek, K. M., & Weeber, E. J. (2005, Spring). Reelin enhances glutamatergic function at hippocampal CA1 synapses in adult mouse. Program No. 487.19. Society for Neuroscience.
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  Abstract Viewer/Itinerary Planner. Washington, DC
• Tanner, D. C., Bolognani, F., Qiu, S. -., Paik, J., Partridge, L. D., Weeber, E. J., & Perrone-Bizzozero, N. I. (2005, Spring). Overexpression of the RNA binding protein HUD leads to alterations in hippocampal connectivity, physiology, and learning and memory. Society for Neuroscience.
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  Program No. 504.16. 2005 Abstract Viewer/Itinerary Planner
• Qiu, S. -., Curras-Collazo, M. C., Jebelli, A. K., & Ashe, J. H. (2003, Spring). Brief exposure to domoic acid induces long-lasting enhancement of CA1 field potentials in a PKA and CaMKII-dependent manner. Society for Neuroscience Meeting.
• Qiu, S. -., Curras-Collazo, M. C., Jebelli, A. K., & Ashe, J. H. (2003, Spring). Domoic acid-induced hippocampal plasticity changes may underlie its neurotoxicity. UC TSR&TP Annual Symposium.
• Qiu, S. -., Jebelli, A. K., Curras-Collazo, M. C., & Ashe, J. H. (2003, Spring). Brief exposure to domoic acid induces long-lasting enhancement of CA1 field potentials in a PKA and/or CaMKII-dependent manner. Society for Neuroscience.
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  Program No. 584.18. 2003 Abstract Viewer/Itinerary Planner
• Qiu, S. -., & Curras-Collazo, M. C. (2002, Spring). Characterization of domoic acid neurotoxicity using in vitro mixed cortical cultures. UC TSR&TP Annual Symposium.
• Qiu, S. -., Curras-Collazo, M. C., Jebelli, A. K., & Ashe, J. H. (2002, Spring). Brief Exposure to Domoic acid induces changes of evoked CA1 hippocampal field potentials. Experimental Biology Meeting Abstract.