- Professor, Pharmacogenomics
- Professor, Pharmacology and Toxicology
- Associate, Center for Toxicology
- Professor, Applied BioSciences - GIDP
- Professor, Cancer Biology - GIDP
- Professor, Pharmacology
- Professor, Genetics - GIDP
- Ph.D. Biochemistry
- Clarkson University, Potsdam, New York, USA
- Mechanism of Cysteine Conjugate Toxicity
- Distinguished Chinese Toxicology Scholar
- Society of Toxicology, Spring 2015
Molecular Biology of Oxidative Stress,Stress Hormones,Mechanism of Protein Translation under Stress Conditions,Nrf2 Transcription factor,Cytoprotection,Cardiac Protection,Biomarkers of cardiac injury
Pharmacology (History, Over Counter Drugs, Endocrine Drugs, Chemotherapy Drugs, Drug Development)Biochemistry (Protein Translation, Proteases, Transcription Factors)Cell Biology (Cell Death, Stress Signaling, Senescence)
INDBIOC 492 (Spring 2020)
INDBIOC 498 (Spring 2020)
INDMCB 498H (Spring 2020)
INDMCB 792 (Spring 2020)
INDPHCL 910 (Spring 2020)
LECPHPR 887 (Spring 2020)
SEMPHCL 696A (Spring 2020)
CLQCBIO 695A (Fall 2019)
INDBIOC 498 (Fall 2019)
INDCBIO 900 (Fall 2019)
INDMCB 498H (Fall 2019)
LECPHCL 412 (Fall 2019)
LECPHCL 512 (Fall 2019)
SEMPHCL 696A (Fall 2019)
CLQMCB 795A (Spring 2019)
INDBIOC 392H (Spring 2019)
INDECOL 498H (Fall 2018)
LECCBIO 630B (Fall 2018)
LECPCOL 630B (Fall 2018)
LECPHCL 412 (Fall 2018)
LECPHCL 512 (Fall 2018)
INDBIOC 492 (Spring 2018)
INDBIOC 499H (Fall 2017)
LECCBIO 630B (Fall 2017)
LECPCOL 630B (Fall 2017)
LECPHCL 412 (Fall 2017)
LECPHCL 512 (Fall 2017)
INDPSIO 492 (Spring 2017)
INDBIOC 492 (Fall 2016)
INDMCB 499 (Fall 2016)
INDPHCL 499 (Fall 2016)
LECCBIO 630B (Fall 2016)
LECPCOL 630B (Fall 2016)
LECPHCL 412 (Fall 2016)
LECPHCL 512 (Fall 2016)
CLQMCB 795A (Spring 2016)
INDABS 593A (Spring 2016)
INDABS 909 (Spring 2016)
INDBIOC 492 (Spring 2016)
INDMCB 392 (Spring 2016)
INDMCB 492 (Spring 2016)
INDPHCL 499 (Spring 2016)
- Chen, Q. (2019). Imaging Assessment of Cardioprotection Mediated by a Dodecafluoropentane Oxygen-Carrier Administered during Myocardial Infarction. Nuclear Med Biol, 70, 67-77. doi:10.1016
- Chen, Q. (2019). Myocardial Infarction with Nonobstructive Coronary Arteries (MINOCA). Am. J. Med., 132(3), 267-268.
- Chen, Q. M., & Maltagliati, A. J. (2018). Nrf2 at the heart of oxidative stress and cardiac protection. Physiological genomics, 50(2), 77-97.More infoThe NFE2L2 gene encodes the transcription factor Nrf2 best known for regulating the expression of antioxidant and detoxification genes. Gene knockout approaches have demonstrated its universal cytoprotective features. While Nrf2 has been the topic of intensive research in cancer biology since its discovery in 1994, understanding the role of Nrf2 in cardiovascular disease has just begun. The literature concerning Nrf2 in experimental models of atherosclerosis, ischemia, reperfusion, cardiac hypertrophy, heart failure, and diabetes supports its cardiac protective character. In addition to antioxidant and detoxification genes, Nrf2 has been found to regulate genes participating in cell signaling, transcription, anabolic metabolism, autophagy, cell proliferation, extracellular matrix remodeling, and organ development, suggesting that Nrf2 governs damage resistance as well as wound repair and tissue remodeling. A long list of small molecules, most derived from natural products, have been characterized as Nrf2 inducers. These compounds disrupt Keap1-mediated Nrf2 ubquitination, thereby prohibiting proteasomal degradation and allowing Nrf2 protein to accumulate and translocate to the nucleus, where Nrf2 interacts with sMaf to bind to ARE in the promoter of genes. Recently alternative mechanisms driving Nrf2 protein increase have been revealed, including removal of Keap1 by autophagy due to p62/SQSTM1 binding, inhibition of βTrCP or Synoviolin/Hrd1-mediated ubiquitination of Nrf2, and de novo Nrf2 protein translation. We review here a large volume of literature reporting historical and recent discoveries about the function and regulation of Nrf2 gene. Multiple lines of evidence presented here support the potential of dialing up the Nrf2 pathway for cardiac protection in the clinic.
- Chen, Q., & Harrill, A. (2018). Interview with a Member: Drs. Curtis D. Klaassen, Nathan Cherrington, Lauren Aleksunes. Pharmacologist.
- Alpert, J., & Chen, Q. (2017). Stem cell therapy: The phoenix in clinical medicine. American Journal of Medicine, 130(9), 1003-1004.
- Lee, S. C., Zhang, J., Strom, J., Yang, D., Dinh, T. N., Kappeler, K., & Chen, Q. M. (2017). G-Quadruplex in the NRF2 mRNA 5' Untranslated Region Regulates De Novo NRF2 Protein Translation under Oxidative Stress. Molecular and cellular biology, 37(1).More infoInhibition of protein synthesis serves as a general measure of cellular consequences of chemical stress. A few proteins are translated selectively and influence cell fate. How these proteins can bypass the general control of translation remains unknown. We found that low to mild doses of oxidants induce de novo translation of the NRF2 protein. Here we demonstrate the presence of a G-quadruplex structure in the 5' untranslated region (UTR) of NRF2 mRNA, as measured by circular dichroism, nuclear magnetic resonance, and dimethylsulfate footprinting analyses. Such a structure is important for 5'-UTR activity, since its removal by sequence mutation eliminated H2O2-induced activation of the NRF2 5' UTR. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomics revealed elongation factor 1 alpha (EF1a) as a protein binding to the G-quadruplex sequence. Cells responded to H2O2 treatment by increasing the EF1a protein association with NRF2 mRNA, as measured by RNA-protein interaction assays. The EF1a interaction with small and large subunits of ribosomes did not appear to change due to H2O2 treatment, nor did posttranslational modifications, as measured by two-dimensional (2-D) Western blot analysis. Since NRF2 encodes a transcription factor essential for protection against tissue injury, our data have revealed a novel mechanism of cellular defense involving de novo NRF2 protein translation governed by the EF1a interaction with the G-quadruplex in the NRF2 5' UTR during oxidative stress.
- Strom, J., & Chen, Q. (2017). Loss of Nrf2 Promotes Rapid Progression to Heart Failure following Myocardial Infarction. Toxicol. Appl. Pharmacol, 327, 52-58.
- Chen, Q., & Alpert, J. S. (2016). Nutraceuticals: Beneficial in Clinical Practice. American Journal of Medicine.
- Chen, Q., & Alpert, J. S. (2016). To Sup or Not to Sup: Is There Any Role of Antioxidant Vitamins in the Management of Heart Failure?. American Journal of Medicine.
- Morrissy, S. J., Sun, H., Zhang, J., Strom, J., & Chen, Q. M. (2016). Differential Regulation of Bcl-xL Gene Expression by Corticosterone, Progesterone, and Retinoic Acid. Journal of biochemical and molecular toxicology.More infoCorticosterone (CT), progesterone (PG), and retinoic acid (RA) are capable of inhibiting Doxorubicin (Dox) from inducing apoptosis in rat cardiomyocytes. Mechanistically, CT, PG, and RA induce increases of Bcl-xL protein and mRNA, and activate a 3.2 kb bcl-x gene promoter. CT and RA, but not PG, induced the activity of a 0.9 kb bcl-x promoter, containing sequences for AP-1 and NF-kB binding. RA, but not CT or PG, induced NF-kB activation. CT, but not PG or RA, induced AP-1 activation, and induction of the 0.9 kb bcl-x reporter by CT was inhibited by dominant negative c-Jun TAM-67 or removal of AP-1 binding site. Therefore, although CT, PG, and RA all induce Bcl-xL mRNA and protein, three independent mechanisms are in operation: while CT induces Bcl-xL via AP-1 transcription factor, and RA induces NF-kB activation and bcl-x promoter activity, PG induces Bcl-xL via a mechanism independent of NF-kB or AP-1.
- Strom, J., Xu, B., Tian, X., & Chen, Q. M. (2015). Nrf2 protects mitochondrial decay by oxidative stress. FASEB journal : official publication of the Federation of American Societies for Experimental Biology.More infoSublethal levels of oxidative stress are commonly associated with various pathophysiological conditions. Cardiomyocytes have the highest content of mitochondria among all cell types, allowing the study of mitochondria in cells surviving oxidative stress and address whether Nuclear factor-erythroid-derived 2-related factor 2 (Nrf2) can reverse these changes. Mitochondria normally exist in elaborated networks, which were replaced by predominately individual punctuate mitochondria 24 h after exposure to a nonlethal dose of H2O2. Electron microscopy revealed that cells surviving H2O2 show swelling of mitochondria with disorganized cristae and areas of condensation. Measurements of functional mitochondria showed a H2O2 dose-dependent decrease over a course of 5 d. At the protein and mRNA levels, cells surviving H2O2 treatment show a reduction of mitochondrial components, cytochrome c, and cytochrome b. Nrf2 overexpression prevented H2O2 from inducing mitochondria morphologic changes and reduction of cytochrome b/c. Although Nrf2 is known as a transcription factor regulating antioxidant and detoxification genes, Nrf2 overexpression did not significantly reduce the level of protein oxidation. Instead, Nrf2 was found to associate with the outer mitochondrial membrane. Mitochondria prepared from the myocardium of Nrf2 knockout mice are more sensitive to permeability transition. Our data suggest that Nrf2 protects mitochondria from oxidant injury likely through direct interaction with mitochondria.-Strom, J., Xu, B., Tian, X., Chen, Q. M. Nrf2 protects mitochondrial decay by oxidative stress.
- Aguilar, D., Strom, J., & Chen, Q. M. (2014). Glucocorticoid induced leucine zipper inhibits apoptosis of cardiomyocytes by doxorubicin. Toxicology and applied pharmacology, 276(1), 55-62.More infoDoxorubicin (Dox) is an indispensable chemotherapeutic agent for the treatment of various forms of neoplasia such as lung, breast, ovarian, and bladder cancers. Cardiotoxicity is a major concern for patients receiving Dox therapy. Previous work from our laboratory indicated that glucocorticoids (GCs) alleviate Dox-induced apoptosis in cardiomyocytes. Here we have found glucocorticoid-induced leucine zipper (GILZ) to be a mediator of GC-induced cytoprotection. GILZ was found to be induced in cardiomyocytes by GC treatment. Knocking down of GILZ using siRNA resulted in cancelation of GC-induced cytoprotection against apoptosis by Dox treatment. Overexpressing GILZ by transfection was able to protect cells from apoptosis induced by Dox as measured by caspase activation, Annexin V binding and morphologic changes. Western blot analyses indicate that GILZ overexpression prevented cytochrome c release from mitochondria and cleavage of caspase-3. When bcl-2 family proteins were examined, we found that GILZ overexpression causes induction of the pro-survival protein Bcl-xL. Since siRNA against Bcl-xL reverses GC induced cytoprotection, Bcl-xL induction represents an important event in GILZ-induced cytoprotection. Our data suggest that GILZ functions as a cytoprotective gene in cardiomyocytes.
- Strom, J., Swyers, T., Wilson, D., Unger, E., Chen, Q. M., & Larson, D. F. (2014). Dodecafluoropentane emulsion elicits cardiac protection against myocardial infarction through an ATP-Sensitive K+ channel dependent mechanism. Cardiovascular drugs and therapy / sponsored by the International Society of Cardiovascular Pharmacotherapy, 28(6), 541-7.More infoDodecafluoropentane emulsion (DDFPe) is a perfluorocarbon with high oxygen dissolving, transport, and delivery capacity that may offer the potential to limit ischemic injury prior to clinical reperfusion. Here we investigated the cardiac protective potential of DDFPe in a mouse model of myocardial infarction.
- Xu, B., Zhang, J., Strom, J., Lee, S., & Chen, Q. M. (2014). Myocardial ischemic reperfusion induces de novo Nrf2 protein translation. Biochimica et biophysica acta, 1842(9), 1638-47.More infoNrf2 is a bZIP transcription factor regulating the expression of antioxidant and detoxification genes. We have found that Nrf2 knockout mice have an increased infarction size in response to regional ischemic reperfusion and have a reduced degree of cardiac protection by means of ischemic preconditioning. With cycles of brief ischemia and reperfusion (5'I/5'R) that induce cardiac protection in wild type mice, an elevated Nrf2 protein was observed without prior increases of Nrf2 mRNA. When an mRNA species is being translated into a protein, it is occupied by multiple ribosomes. The level of ribosome-associated Nrf2 mRNA increased following cycles of 5'I/5'R, supporting de novo Nrf2 protein translation. A dicistronic reporter assay indicated a role of the 5' untranslated region (5' UTR) of Nrf2 mRNA in oxidative stress induced Nrf2 protein translation in isolated cardiomyocytes. Western blot analyses after isolation of proteins binding to biotinylated Nrf2 5' UTR from the myocardium or cultured cardiomyocytes demonstrated that cycles of 5'I/5'R or oxidants caused an increased association of La protein with Nrf2 5' UTR. Ribonucleoprotein complex immunoprecipitation assays confirmed such association indeed occurring in vivo. Knocking down La using siRNA was able to prevent Nrf2 protein elevation by oxidants in cultured cardiomyocytes and by cycles of 5'I/5'R in the myocardium. Our data point out a novel mechanism of cardiac protection by de novo Nrf2 protein translation involving interaction of La protein with 5' UTR of Nrf2 mRNA in cardiomyocytes.
- Chen, Q., Zhang, J., & Chen, Q. -. (2013). Far upstream element binding protein 1: a commander of transcription, translation and beyond. Oncogene, 32(24).More infoThe far upstream binding protein 1 (FBP1) was first identified as a DNA-binding protein that regulates c-Myc gene transcription through binding to the far upstream element (FUSE) in the promoter region 1.5 kb upstream of the transcription start site. FBP1 collaborates with TFIIH and additional transcription factors for optimal transcription of the c-Myc gene. In recent years, mounting evidence suggests that FBP1 acts as an RNA-binding protein and regulates mRNA translation or stability of genes, such as GAP43, p27(Kip) and nucleophosmin. During retroviral infection, FBP1 binds to and mediates replication of RNA from Hepatitis C and Enterovirus 71. As a nuclear protein, FBP1 may translocate to the cytoplasm in apoptotic cells. The interaction of FBP1 with p38/JTV-1 results in FBP1 ubiquitination and degradation by the proteasomes. Transcriptional and post-transcriptional regulations by FBP1 contribute to cell proliferation, migration or cell death. FBP1 association with carcinogenesis has been reported in c-Myc dependent or independent manner. This review summarizes biochemical features of FBP1, its mechanism of action, FBP family members and the involvement of FBP1 in carcinogenesis.
- Chen, Y. -., Aguilar, D. C., Strom, J., Xu, B., Kappeler, K., & Chen, Q. -. (2013). Expression of glucocorticoid-induced leucine zipper (GILZ) in cardiomyocytes. Cardiovascular toxicology, 13(2).More infoGlucocorticoids (GCs) are frequently prescribed pharmacological agents most notably for their immunosuppressive effects. Endogenous GCs mediate biological processes such as energy metabolism and tissue development. At the cellular level, GCs bind to the glucocorticoid receptor (GR), a cytosolic protein that translocates to the nuclei and functions to alter transcription upon ligand binding. Among a long list of genes activated by GCs is the glucocorticoid-induced leucine zipper (GILZ). GC-induced GILZ expression has been well established in lymphocytes and mediates GC-induced apoptosis. Unlike lymphocytes, cardiomyocytes respond to GCs by gaining resistance against apoptosis. We determined GILZ expression in cardiomyocytes in vivo and in vitro. Expression of GILZ in mouse hearts as a result of GC administration was confirmed by Western blot analyses. GCs induced dose- and time-dependent elevation of GILZ expression in primary cultured rat cardiomyocytes, with dexamethasone (Dex) as low as 0.1 μM being effective. Time course analysis indicated that GILZ protein levels increased at 8 h and peaked at 48 h after exposure to 1 μM Dex. H9c2(2-1) cell line showed a similar response of GILZ induction by Dex as primary cultured rat cardiomyocytes, providing a convenient model for studying the biological significance of GILZ expression. With corticosterone (CT), an endogenous form of corticosteroids in rodents, 0.1-2.5 μM was found to induce GILZ in H9c2(2-1) cells. Time course analysis with 1 μM CT indicated induction of GILZ at 6 h with peak expression at 18 h. Inhibition of the GR by mifepristone led to blunting of GILZ induction by GCs. Our data demonstrate GILZ induction in cardiomyocytes both in vivo and in vitro by GCs, pointing to H9c2(2-1) cells as a valid model for studying the biological function of GILZ in cardiomyocytes.
- Alpert, J. S., & Chen, Q. M. (2012). Has the genomic revolution failed?. Clinical cardiology, 35(3), 178-9.
- Alpert, J. S., & Chen, Q. M. (2012). Modern medicine and the Garden of Eden. The American journal of medicine, 125(11), 1043-4.
- Alpert, J. S., & Chen, Q. M. (2012). So, you want to live to 120? The genie in the bottle. The American journal of medicine, 125(7), 621-2.
- Chen, Y. -., Kappeler, K. V., Zhang, J., Dinh, T. N., Strom, J. G., & Chen, Q. -. (2012). Histone deacetylase 6 associates with ribosomes and regulates de novo protein translation during arsenite stress. Toxicological sciences : an official journal of the Society of Toxicology, 127(1).More infoHistone deacetylase 6 (HDAC6) is known as a cytoplasmic enzyme that regulates cell migration, cell adhesion, and degradation of misfolded proteins by deacetylating substrates such as α-tubulin and Hsp90. When HaCaT keratinocytes were exposed to 1-200μM sodium arsenite, we observed perinuclear localization of HDAC6 within 30 min. Although the overall level of HDAC6 protein did not change, sodium arsenite caused an increase of HDAC6 in ribosomal fractions. Separation of ribosomal subunits versus intact ribosomes or polysomes indicated that HDAC6 was mainly detected in 40/43S fractions containing the small ribosomal subunit in untreated cells but was associated with 40/43S and 60/80S ribosomal fractions in arsenite-treated cells. Immunocytochemistry studies revealed that arsenite caused colocalization of HDAC6 with the ribosomal large and small subunit protein L36a and S6. Both L36a and S6 were detected in the immunocomplex of HDAC6 isolated from arsenite-treated cells. The observed physical interaction of HDAC6 with ribosomes pointed to a role of HDAC6 in stress-induced protein translation. Among arsenite stress-induced proteins, de novo Nrf2 protein translation was inhibited by Tubastatin A. These data demonstrate that HDAC6 was recruited to ribosomes, physically interacted with ribosomal proteins, and regulated de novo protein translation in keratinocytes responding to arsenite stress.
- Chen, Y. -., Morrissy, S., Strom, J., Purdom-Dickinson, S., & Chen, Q. -. (2012). NAD(P)H:quinone oxidoreductase 1 is induced by progesterone in cardiomyocytes. Cardiovascular toxicology, 12(2).More infoNAD(P)H: quinone oxidoreductase 1 (NQO1) is a ubiquitous flavoenzyme that catalyzes two-electron reduction of various quinones by utilizing NAD(P)H as an electron donor. Our previous study found that progesterone (PG) can protect cardiomyocytes from apoptosis induced by doxorubicin (Dox). Microarray analyses of genes induced by PG had led to the discovery of induction of NQO1 mRNA. We report here that PG induces NQO1 protein and its activity in a dose-dependent manner. Whereas NQO1 is well known as a target gene of Nrf2 transcription factor due to the presence of antioxidant response element (ARE) in the promoter, PG did not activate the ARE, suggesting Nrf2-independent induction of NQO1. To address the role of NQO1 induction in PG-induced cytoprotection, we tested the effect of NQO1 inducer β-naphthoflavone and inhibitor dicoumarol. Induction of NQO1 by β-naphthoflavone decreased Dox-induced apoptosis and potentiated the protective effect of PG as measured by caspase-3 activity. PG-induced NQO1 activity was inhibited with dicoumarol, which did not affect PG-induced cytoprotection. Dicoumarol treatment alone potentiated Dox-induced caspase-3 activity. These data suggest that while NQO1 plays a role in PG-induced cytoprotection, there are additional components contributing to PG-induced cytoprotection.
- Chen, Y. -., Zhang, J., Dinh, T. N., Kappeler, K., Tsaprailis, G., & Chen, Q. -. (2012). La autoantigen mediates oxidant induced de novo Nrf2 protein translation. Molecular & cellular proteomics : MCP, 11(6).More infoNrf2 gene encodes a transcription factor that regulates the expression of a cluster of antioxidant and detoxification genes. Recent works from our laboratory indicate that oxidative stress causes rapid de novo synthesis of Nrf2 protein. We have found that 5' Untranslated Region (5'UTR) of Nrf2 allows the mRNA to undergo an Internal Ribosomal Entry Site (IRES) mediated protein translation. Using liquid chromatography tandem MS, we have discovered that La/SSB protein bound to Nrf2 5'UTR in response to oxidative stress. In vitro RNA binding and in vivo ribonucleoprotein immunoprecipitation showed H(2)O(2) dose and time dependent increases of La/SSB binding to Nrf2 5'UTR. La/SSB protein translocated from the nuclei to cytoplasm and distributed in the perinuclear space in cells treated with H(2)O(2). Isolation of ribosomal fractions indicated that oxidants caused an association of La/SSB with ribosomes. Physical interaction of La/SSB with representative proteins from the small or large subunits of ribosomes was found to increase in cells responding to H(2)O(2) treatment. Knocking down La/SSB gene with siRNA prevented Nrf2 protein elevation or Nrf2 5'UTR activation by oxidants. In contrast, overexpression of La/SSB gene was able to enhance Nrf2 5'UTR activation and Nrf2 protein increase. Our data suggest that oxidants cause nuclear export of La/SSB protein and subsequent association of La/SSB with Nrf2 5'UTR and ribosomes. These events contribute to de novo Nrf2 protein translation because of oxidative stress.
- Chen, Y. -., Terrand, J., Xu, B., Morrissy, S., Dinh, T. N., Williams, S., & Chen, Q. -. (2011). p21(WAF1/Cip1/Sdi1) knockout mice respond to doxorubicin with reduced cardiotoxicity. Toxicology and applied pharmacology, 257(1).More infoDoxorubicin (Dox) is an antineoplastic agent that can cause cardiomyopathy in humans and experimental animals. As an inducer of reactive oxygen species and a DNA damaging agent, Dox causes elevated expression of p21(WAF1/Cip1/Sdi1) (p21) gene. Elevated levels of p21 mRNA and p21 protein have been detected in the myocardium of mice following Dox treatment. With chronic treatment of Dox, wild type (WT) animals develop cardiomyopathy evidenced by elongated nuclei, mitochondrial swelling, myofilamental disarray, reduced cardiac output, reduced ejection fraction, reduced left ventricular contractility, and elevated expression of ANF gene. In contrast, p21 knockout (p21KO) mice did not show significant changes in the same parameters in response to Dox treatment. In an effort to understand the mechanism of the resistance against Dox induced cardiomyopathy, we measured levels of antioxidant enzymes and found that p21KO mice did not contain elevated basal or inducible levels of glutathione peroxidase and catalase. Measurements of 6 circulating cytokines indicated elevation of IL-6, IL-12, IFNγ and TNFα in Dox treated WT mice but not p21KO mice. Dox induced elevation of IL-6 mRNA was detected in the myocardium of WT mice but not p21KO mice. While the mechanism of the resistance against Dox induced cardiomyopathy remains unclear, lack of inflammatory response may contribute to the observed cardiac protection in p21KO mice.
- Chen, Y. -., Xu, B., Strom, J., & Chen, Q. -. (2011). Dexamethasone induces transcriptional activation of Bcl-xL gene and inhibits cardiac injury by myocardial ischemia. European journal of pharmacology, 668(1-2).More infoPsychological or physical stress causes an elevation of glucocorticoids in the circulating system. Glucocorticoids regulate a variety of physiological functions, from energy metabolism and biochemical homeostasis to immune response. Synthetic steroids are among the most prescribed drugs for immune suppression and chemotherapy. While glucocorticoids are best known for inducing apoptosis in a number of cell types, we have found that corticosteroids at stress relevant levels protect cardiomyocytes from apoptosis. Current study addresses whether glucocorticoids inhibit cardiac injury in vivo. Adult male C57BL6 mice were administered with dexamethasone (20mg/kg, i.p.) or vehicle control 20 h prior to left anterior descending coronary artery occlusion surgery. Myocardial infarction was measured by triphenyl tetrazoliumchloride staining in tissue slices and by levels of cardiac Troponin (cTn I) in the blood. Treatment of dexamethasone markedly reduced infarct size (19.6 ± 4.3%, vs. 29.2 ± 4.9%, p
- Chen, Y. -., Morrissy, S., Xu, B., Aguilar, D., Zhang, J., & Chen, Q. -. (2010). Inhibition of apoptosis by progesterone in cardiomyocytes. Aging cell, 9(5).More infoWhile gender-based differences in heart disease have raised the possibility that estrogen (ES) or progesterone (PG) may have cardioprotective effects, recent controversy regarding hormone replacement therapy has questioned the cardiac effects of these steroids. Using cardiomyocytes, we tested whether ES or PG has protective effects at the cellular level. We found that PG but not ES protects cardiomyocytes from apoptotic cell death induced by doxorubicin (Dox). PG inhibited apoptosis in a dose-dependent manner, by 12 ± 4.0% at 1 μm and 60 ± 1.0% at 10 μm. The anti-apoptotic effect of PG was also time dependent, causing 18 ± 5% or 62 + 2% decrease in caspase-3 activity within 1 h or 72 h of pretreatment. While PG causes nuclear translocation of its receptor within 20 min, the cytoprotective effect of PG was canceled by mifepristone (MF), a PG receptor antagonist. Analyses using Affymetrix high-density oligonucleotide array and RT-PCR found that PG induced Bcl-xL, metallothionine, NADPH quinone oxidoreductase 1, glutathione peroxidase-3, and four isoforms of glutathione S-transferase. Western blot analyses revealed that PG indeed induced an elevation of Bcl-xL protein in a dose- and time-dependent manner. Nuclear run-on assay indicated that PG induced Bcl-xL gene transcription. Inhibiting the expression of Bcl-xL using siRNA reduced the cytoprotective effect of PG. Our data suggests that PG induces a cytoprotective effect in cardiomyocytes in association with induction of Bcl-xL gene.
- Chen, Y. -., Xie, L., Terrand, J., Xu, B., Tsaprailis, G., Boyer, J., & Chen, Q. -. (2010). Cystatin C increases in cardiac injury: a role in extracellular matrix protein modulation. Cardiovascular research, 87(4).More infoNumerous lines of evidence suggest a role of oxidative stress in initiation and progression of heart failure. We identify novel pathways of oxidative stress in cardiomyocytes using proteomic technology.
- Chen, Y. -., Xie, L., Pandey, R., Xu, B., Tsaprailis, G., & Chen, Q. -. (2009). Genomic and proteomic profiling of oxidative stress response in human diploid fibroblasts. Biogerontology, 10(2).More infoA number of lines of evidence suggest that senescence of normal human diploid fibroblasts (HDFs) in culture is relevant to the process of aging in vivo. Using normal human skin diploid fibroblasts, we examine the changes in genes and proteins following treatment with a mild dose of H2O2, which induces premature senescence. Multidimensional Protein Identification Technology (MudPIT) in combination with mass spectrometry analyses of whole cell lysates from HDFs detected 65 proteins in control group, 48 proteins in H2O2-treated cells and 109 proteins common in both groups. In contrast, cDNA microarray analyses show 173 genes up-regulated and 179 genes down-regulated upon H2O2 treatment. Both MudPIT and cDNA microarray analyses indicate that H2O2 treatment caused elevated levels of thioredoxin reductase 1. Semi-quantitative RT-PCR and Western-blot were able to verify the finding. Out of a large number of genes or proteins detected, only a small fraction shows the overlap between the outcomes of microarray versus proteomics. The low overlap suggests the importance of considering proteins instead of transcripts when investigating the gene expression profile altered by oxidative stress.
- Chen, Y. -., Sun, H., & Chen, Q. -. (2008). Inhibitors of GSK-3 prevent corticosterone from inducing COX-1 expression in cardiomyocytes. Cardiovascular toxicology, 8(2).More infoOur recent study has demonstrated that glucocorticoids (GCs) induce cyclooxygenase-1 (COX-1) gene expression in rat cardiomyocytes. While investigating the mechanism underlying corticosterone (CT) induced COX-1, we found that three structurally and mechanistically distinct GSK-3 inhibitors, LiCl, SB216763, and (2'Z,3'E)-6-Bromoindirubin-3'-oxime (BIO), inhibited COX-1 transcription and protein induction. A genetic approach of expressing wild type GSK-3beta increased COX-1 promoter activity, which was abolished by LiCl. LiCl increased inhibitory GSK-3alpha/beta phosphorylation at Ser21/Ser9, while BIO or SB216763 prevented stimulatory phosphorylation at Tyr279/Tyr216 of GSK-3alpha/beta. GSK inhibitors failed to block nuclear translocation of glucocorticoid receptor (GR) or activation of glucocorticoid response element (GRE) by CT treatment. While Sp3 transcription factor mediates CT induced COX-1 expression, GSK inhibitors did not change the level of Sp3 protein or binding of Sp3 transcription factor to COX-1 promoter. The observed effect of GSK-3 inhibitors appears to be unique to COX-1 since LiCl or BIO does not prevent CT from inducing COX-2 gene. We conclude that GSK-3 inhibitors block CT from inducing COX-1 gene expression via a mechanism beyond GR and Sp3 transcription factor.
- Chen, Y. -., Sun, H., Sheveleva, E., & Chen, Q. -. (2008). Corticosteroids induce cyclooxygenase 1 expression in cardiomyocytes: role of glucocorticoid receptor and Sp3 transcription factor. Molecular endocrinology (Baltimore, Md.), 22(9).More infoCyclooxygenase (COX) encodes a rate-limiting enzyme in the biosynthesis of prostanoids. Although COX-1 is constitutively expressed in many tissues, we found that glucocorticoids cause elevated expression of COX-1 gene in cardiomyocytes. Corticosterone (CT) at physiologically relevant doses (0.05-1 microm) induces transcriptional activation of COX-1 gene as shown by nuclear run-on and promoter reporter assays. An antagonist of glucocorticoid receptor (GR), mifepristone, prevented CT from inducing COX-1. COX-1 gene promoter deletion and mutation studies indicate a role of Sp transcription factors in CT-induced COX-1 gene. EMSAs or chromatin immunoprecipitation assays suggest that GR and Sp3 transcription factor bind to the promoter of COX-1 gene. Coimmunoprecipitation assays found an association of GR with Sp3. Silencing Sp3 protein with small interfering RNA suppressed CT-induced COX-1 promoter activation. Our data suggest that activated GR interacts with Sp3 transcription factor in binding to COX-1 promoter to enhance COX-1 gene expression in cardiomyocytes.
- Chen, Y. -., Sun, H., Sheveleva, E., Xu, B., Inoue, H., Bowden, T. G., & Chen, Q. -. (2008). Corticosteroids induce COX-2 expression in cardiomyocytes: role of glucocorticoid receptor and C/EBP-beta. American journal of physiology. Cell physiology, 295(4).More infoPsychological stress increases the level of glucocorticoids in the circulating system. We found that dexamethasone administration in adult mice elevates the expression of COX-2 in the myocardium. With isolated neonatal cardiomyocytes, corticosterone (CT) at physiologically relevant doses (0.01-1 microM) induces the expression of COX-2 gene. The induction first appeared at 4 h and remained for at least 24 h with 1 microM CT treatment. This response is likely cardiomyocyte cell type specific since CT did not induce COX-2 expression in cardiac fibroblasts and glucocorticoids are known to suppress the expression of COX-2 in lymphocytes and several organs. Corticosteroids, but not estrogen or progesterone, induce COX-2 expression. The glucocorticoid receptor (GR) antagonist mifepristone (MF) prevented CT from inducing COX-2 gene, suggesting a GR-dependent induction in cardiomyocytes. COX-2 gene promoter deletion and mutation studies indicate a role of CCAAT/enhancer binding protein-beta (C/EBP-beta) in CT-induced COX-2 gene expression. Chromatin immunoprecipitation assays revealed that CT caused the binding of both GR and C/EBP-beta to COX-2 promoter, while MF pretreatment blocked such binding. Coimmunoprecipitation experiments demonstrated that CT treatment induced the interaction of GR with C/EBP-beta. Small interfering RNA against C/EBP-beta prevented CT from activating COX-2 promoter or elevating COX-2 protein. Our data suggest that the interaction between GR and C/EBP-beta contributes to elevated COX-2 gene transcription by CT in cardiomyocytes.
- Chen, Y. -., Sun, H., Xu, B., Inoue, H., & Chen, Q. -. (2008). P38 MAPK mediates COX-2 gene expression by corticosterone in cardiomyocytes. Cellular signalling, 20(11).More infoRecent work from our laboratory found that corticosteroids induce transcriptional activation of cyclooxygenase-2 (COX-2) gene in cardiomyocytes. Here we report that COX-2 gene promoter mutation studies indicate a role of cAMP response element-binding protein (CREB) in corticosterone-induced COX-2 gene expression. Corticosterone causes activation of p38 MAPK and subsequent CREB phosphorylation at serine 133 in cardiomyocytes. The inhibitors of p38 MAPK, SB202190 and SB203580, block corticosterone from inducing CREB phosphorylation and COX-2 gene expression while dominant-negative p38 MAPK or CREB prevents corticosterone from activating COX-2 promoter. Corticosterone does not induce p38 MAPK activation or COX2 expression in cardiac fibroblasts or HEK293 cells transfected with glucocorticoid receptor, suggesting that p38 MAPK activation is cell specific and necessary for corticosterone-induced COX-2 expression in cardiomyocytes. While glucocorticoid receptor antagonist mifepristone inhibits COX-2 gene induction by corticosterone, mifepristone fails to inhibit p38 MAPK activation or CREB phosphorylation. In contrast, inhibition of p38 MAPK does not prevent corticosterone from activating glucocorticoid receptor. Our data suggest that two parallel signaling pathways, glucocorticoid receptor and p38 MAPK, act in concert to regulate the expression of COX-2 gene in cardiomyocytes.
- Chen, Y. -., Sun, H., Xu, B., Sheveleva, E., & Chen, Q. -. (2008). LY294002 inhibits glucocorticoid-induced COX-2 gene expression in cardiomyocytes through a phosphatidylinositol 3 kinase-independent mechanism. Toxicology and applied pharmacology, 232(1).More infoGlucocorticoids induce COX-2 expression in rat cardiomyocytes. While investigating whether phosphatidylinositol 3 kinase (PI3K) plays a role in corticosterone (CT)-induced COX-2, we found that LY294002 (LY29) but not wortmannin (WM) attenuates CT from inducing COX-2 gene expression. Expression of a dominant-negative mutant of p85 subunit of PI3K failed to inhibit CT from inducing COX-2 expression. CT did not activate PI3K/AKT signaling pathway whereas LY29 and WM decreased the activity of PI3K. LY303511 (LY30), a structural analogue and a negative control for PI3K inhibitory activity of LY29, also suppressed COX-2 induction. These data suggest PI3K-independent mechanisms in regulating CT-induced COX-2 expression. LY29 and LY30 do not inhibit glucocorticoid receptor transactivity. Both compounds have been reported to inhibit Casein Kinase 2 activity and modulate potassium and calcium levels independent of PI3K, while LY29 has been reported to inhibit mammalian Target of Rapamycin (mTOR), and DNA-dependent Protein Kinase (DNA-PK). Inhibitor of Casein Kinase 2 (CK2), mTOR or DNA-PK failed to prevent CT from inducing COX-2 expression. Tetraethylammonium (TEA), a potassium channel blocker, and nimodipine, a calcium channel blocker, both attenuated CT from inducing COX-2 gene expression. CT was found to increase intracellular Ca(2+) concentration, which can be inhibited by LY29, TEA or nimodipine. These data suggest a possible role of calcium instead of PI3K in CT-induced COX-2 expression in cardiomyocytes.
- Pysher, M. D., Chen, Q. M., & Vaillancourt, R. R. (2008). Arsenic alters vascular smooth muscle cell focal adhesion complexes leading to activation of FAK-src mediated pathways. Toxicology and applied pharmacology, 231(2), 135-41.More infoChronic exposure to arsenic has been linked to tumorigenesis, cardiovascular disease, hypertension, atherosclerosis, and peripheral vascular disease; however, the molecular mechanisms underlying its pathological effects remain elusive. In this study, we investigated arsenic-induced alteration of focal adhesion protein complexes in normal, primary vascular smooth muscle cells. We demonstrate that exposure to environmentally relevant concentrations of arsenic (50 ppb As(3+)) can alter focal adhesion protein co-association leading to activation of downstream pathways. Co-associated proteins were identified and quantitated via co-immunoprecipitation, SDS-PAGE, and Western blot analysis followed by scanning densitometry. Activation of MAPK pathways in total cell lysates was evaluated using phosphor-specific antibodies. In our model, arsenic treatment caused a sustained increase in FAK-src association and activation, and induced the formation of unique signaling complexes (beginning after 3-hour As(3+) exposure and continuing throughout the 12-hour time course studied). The effects of these alterations were manifested as chronic stimulation of downstream PAK, ERK and JNK pathways. Past studies have demonstrated that these pathways are involved in cellular survival, growth, proliferation, and migration in VSMCs.
- Chen, Y. -., Purdom-Dickinson, S. E., Lin, Y., Dedek, M., Morrissy, S., Johnson, J., & Chen, Q. -. (2007). Induction of antioxidant and detoxification response by oxidants in cardiomyocytes: evidence from gene expression profiling and activation of Nrf2 transcription factor. Journal of molecular and cellular cardiology, 42(1).More infoMild or low doses of oxidants are known to prime cells towards resistance against further damage. In cardiomyocytes, we found that pretreatment with 100 microM H(2)O(2) prevents the cells from apoptosis induced by doxorubicin (Dox). Affymetrix microarray analyses of 28,000 genes reveal that H(2)O(2) treated cells reduced expression of genes encoding cytochrome c, mitochondrial complex I, III, IV and V and several contractile proteins. Elevated expression of antioxidant and detoxification genes appears as a dominant feature of the gene expression profile of H(2)O(2) treated cells. Most of the genes in this category contain an Antioxidant Response Element (ARE) in their promoters. Measurements of ARE promoter-reporter gene activity indicate a dose- and time-dependent activation of the ARE by H(2)O(2). Since the Nrf2 transcription factor regulates ARE-mediated gene expression, we overexpressed Nrf2 to test whether activation of Nrf2 is sufficient to induce cytoprotection. High levels of Nrf2 expression were achieved via adenovirus mediated gene delivery. Transduced Nrf2 was present in the nuclei and caused an increase in the expression of NAD(P)H:quinone oxidoreductase 1 (NQO1), a representative downstream target of Nrf2. Unlike H(2)O(2) pretreated cells, the cells expressing high levels of Nrf2 were not resistant to Dox-induced apoptosis. Therefore, the cytoprotective effect of H(2)O(2) pretreatment is not reliant upon Nrf2 activation alone as measured by resistance against Dox-induced apoptosis.
- Chen, Y. -., Purdom-Dickinson, S. E., Sheveleva, E. V., Sun, H., & Chen, Q. -. (2007). Translational control of nrf2 protein in activation of antioxidant response by oxidants. Molecular pharmacology, 72(4).More infoNf-E2 related factor-2 (Nrf2) is a basic leucine zipper transcription factor that binds and activates the antioxidant response element (ARE) in the promoters of many antioxidant and detoxification genes. We found that H(2)O(2) treatment caused a rapid increase in endogenous Nrf2 protein level in rat cardiomyocytes. Semiquantitative or real-time reverse transcription-polymerase chain reaction failed to show an increase of Nrf2 mRNA level by H(2)O(2) treatment. Measurements of Nrf2 protein stability excluded the possibility of Nrf2 protein stabilization. Although inhibiting protein synthesis with cycloheximide prevented H(2)O(2) from elevating Nrf2 protein level, RNA synthesis inhibition with actinomycin D failed to do so. Measurements of new protein synthesis with [(35)S]methionine incorporation confirmed that H(2)O(2) increased the translation of Nrf2 protein. Inhibitors of phosphoinositide 3-kinase were able to abolish the induction of Nrf2 protein by H(2)O(2). Although H(2)O(2) increased phosphorylation of p70 S6 kinase, rapamycin failed to inhibit H(2)O(2) from elevating Nrf2 protein. H(2)O(2) also induced phosphorylation of eukaryotic translation initiation factor (eIF) 4E and eIF2alpha within 30 and 10 min, respectively. Inhibiting eIF4E with small interfering siRNA or increasing eIF2alpha phosphorylation with salubrinal did not affect Nrf2 elevation by H(2)O(2). Our data present a novel phenomenon of quick onset of the antioxidant/detoxification response via increased translation of Nrf2 by oxidants. The mechanism underlying such stress-induced de novo protein translation may involve multiple components of translational machinery.
- Chen, Y. -., Tu, V. C., Sun, H., Bowden, G. T., & Chen, Q. -. (2007). Involvement of oxidants and AP-1 in angiotensin II-activated NFAT3 transcription factor. American journal of physiology. Cell physiology, 292(4).More infoCardiomyocyte hypertrophy is associated with multiple pathophysiological cardiovascular conditions. Recent studies have substantiated the finding that oxidants may contribute to the development of cardiomyocyte hypertrophy. Activation of the nuclear factor of activated T cells-3 (NFAT3) transcription factor has been shown to result from endocrine inducers of cardiomyocyte hypertrophy such as angiotensin II (ANG II) and serves as an important molecular regulator of cardiomyocyte hypertrophy. In this study, we found that antioxidant enzyme catalase and antioxidants N-acetyl-l-cysteine, alpha-phenyl-N-tert-butylnitrone, and lipoic acid prevent ANG II from activating NFAT3 promoter-luciferase. H(2)O(2) induces a time- and dose-dependent activation of NFAT3 transcription factor. A dominant negative form of NFAT3 transcription factor inhibited H(2)O(2) from activating NFAT3 promoter. An inhibitor of ERKs, but not phosphoinositide 3-kinase or p38 MAPKs, blocked NFAT3 activation by H(2)O(2). The NFAT3 binding site in the promoters of most genes contains a weak activator protein-1 (AP-1) binding site adjacent to the core consensus NFAT binding sequence. ERK inhibitor PD98059 was found previously to inhibit AP-1 activation by H(2)O(2). Inactivation of AP-1 transcription factor by cotransfection of a dominant negative c-Jun, TAM67, prevented H(2)O(2) or ANG II from activating NFAT3 promoter. NFAT3 promoter containing the core NFAT cis-element without AP-1 binding site failed to show activation by H(2)O(2) treatment. Our data suggest that hypertrophy inducers ANG II and H(2)O(2) may activate NFAT3 in cardiomyocyte through an AP-1 transcription factor-dependent mechanism.
- Chen, Y. -., Purdom, S., & Chen, Q. -. (2005). Epidermal growth factor receptor-dependent and -independent pathways in hydrogen peroxide-induced mitogen-activated protein kinase activation in cardiomyocytes and heart fibroblasts. The Journal of pharmacology and experimental therapeutics, 312(3).More infoMild doses of oxidative stress in the heart correlate with the induction of apoptosis or hypertrophy in cardiomyocytes (CMCs) and fibrosis or proliferation of fibroblasts. Three branches of mitogen-activated protein kinases (MAPKs), i.e., c-Jun N-terminal kinases (JNKs), extracellular signal-related kinases 1 and 2 (ERK1/2), and p38, are activated by oxidants in a variety of cell types, including CMCs. However, the initiation process of these signaling pathways remains unsolved. We explored the role of the epidermal growth factor (EGF) receptor in H(2)O(2)-induced MAPK activation using two different cell types from the same organ: CMCs and heart fibroblasts (HFs). Pretreatment of each cell type with EGF revealed differences in how CMCs and HFs responded to subsequent treatment with H(2)O(2): in CMCs, the second treatment resulted in little further activation of JNKs and ERK1/2, whereas HFs retained the full response of JNKs and ERK1/2 activation by H(2)O(2) regardless of EGF pretreatment. AG-1478 [4-(3'-chloroanilino)-6,7-dimethoxy-quinazoline], a pharmacologic inhibitor of the EGF receptor tyrosine kinase, inhibited JNK and ERK1/2 activations but not p38 in both cell types. The data using the Src inhibitor PP2 [4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine] resemble those found when using AG-1478 in either cell type. Pharmacologic inhibitors of matrix metalloproteinases (MMPs) further illustrated the difference between the two cell types. In HFs, MMP inhibitors GM6001 [N-[(2R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl]-l-tryptophan methylamide] and BB2516 [[2S-[N4(R(*)),2R(*),3S(*)]]-N4-[2,2-dimethyl-1-[(methylamino)carbonyl]propyl]-N1,2-dihydroxy-3-(2-methylpropyl)butanediamide, marimastat] inhibited JNKs and ERK1/2 activation without affecting p38 activation by H(2)O(2) inhibitors. In contrast, these MMP failed to significantly inhibit the activation of JNKs, ERKs, or p38 in CMCs. These data suggest the complexity of the cell type-dependent signaling web initiated by oxidants in the heart.
- Chen, Y. -., Xie, L., Tsaprailis, G., & Chen, Q. -. (2005). Proteomic identification of insulin-like growth factor-binding protein-6 induced by sublethal H2O2 stress from human diploid fibroblasts. Molecular & cellular proteomics : MCP, 4(9).More infoFibroblasts are the most ubiquitous cell types within our body. They produce various factors to maintain the texture and structure of a particular organ or tissue. To identify protein factors secreted by fibroblasts and alteration of these protein factors upon oxidative stress, HCA3 human skin diploid fibroblasts were exposed to a sublethal dose of H2O2, which induces a prematurely senescent phenotype. Conditioned media from prematurely senescent cells versus control cells were analyzed for proteins using an LC-MS/MS-based proteomic technique. Collagen alpha1(VI), collagen alpha2(I), fibronectin, lumican, and matrix metalloproteinase 2 were among the proteins consistently detected from control and H2O2-treated cells. Insulin-like growth factor-binding protein-6 (IGFBP-6) consistently showed up in the conditioned medium of H2O2-treated cells but not from untreated cells. Increased IGFBP-6 production due to H2O2 treatment was confirmed by RT-PCR and Western blot analyses. While H2O2 induced a dose-dependent elevation of IGFBP-6 mRNA, Western blot analyses detected elevated levels of IGFBP-6 protein in the conditioned medium of H2O2-treated cells. In comparison, fibronectin or matrix metalloproteinase 2 did not show changes at the mRNA level in cell lysates or at the protein level in the conditioned medium by H2O2 treatment. Using several types of toxins at sublethal doses, including cis-platin, hydroxyurea, colchicine, L-mimosine, rhodamine, dithiothreitol, or N-ethylmaleimide, we found that these agents induced increases of IGFBP-6 at mRNA and protein levels. An increased level of IGFBP-6 protein was detected in the plasma of aging mice and of young mice treated with doxorubicin. These data suggest that IGFBP-6 may serve as a sensitive biomarker of cell degeneration or injury in vitro and in vivo.
- Chen, Y. -., Coronella-Wood, J., Terrand, J., Sun, H., & Chen, Q. -. (2004). c-Fos phosphorylation induced by H2O2 prevents proteasomal degradation of c-Fos in cardiomyocytes. The Journal of biological chemistry, 279(32).More infoOxidants cause activation of the AP-1 transcription factor in cardiomyocytes. c-Fos, a component of the AP-1 transcription factor, is transiently induced by H2O2 and the induction is sensitive to the protein synthesis inhibitor cycloheximide. With high percentage gel electrophoresis, multiple c-Fos bands were resolved by Western blot analyses, indicating post-translational modification of newly synthesized c-Fos protein after H2O2 exposure. Treatment of immunoprecipitated c-Fos protein with the type 2 serine/threonine phosphatase A (PP2A) and immunoblotting of c-Fos protein with antibodies against phosphorylated serine or threonine demonstrated that c-Fos was phosphorylated at serine residues. A pharmacological inhibitor of JNKs inhibited the formation of multiple c-Fos bands without affecting c-fos transcription. The proteasomal inhibitor MG132 and Proteasome Inhibitor I extended the time course of c-Fos protein elevation. An increase in ubiquitin was detectable in c-Fos protein from H2O2-treated cells. Interestingly, treating the whole cell lysates with PP2A, but not calcineurin (i.e. PP2B), resulted in disappearance of c-Fos protein and MG132 was able to prevent this loss. H2O2 caused an elevation of PP2B and total phosphatase activity. The phosphatase inhibitor okadaic acid, but not PP2B inhibiter cypermethrin, extended the time course of c-Fos protein elevation after H2O2 exposure. These data suggest that JNK-mediated phosphorylation of newly synthesized c-Fos protects the protein from being degraded by the proteasome. PP2B independent dephosphorylation contributes to degradation of c-Fos protein during oxidative stress response of cardiomyocytes.
- Chen, Y. -., Dilley, T. K., Bowden, G. T., & Chen, Q. -. (2003). Novel mechanisms of sublethal oxidant toxicity: induction of premature senescence in human fibroblasts confers tumor promoter activity. Experimental cell research, 290(1).More infoAging is the highest risk factor for cancer. Although oxidants are thought to contribute to both aging and cancer, the interplay between oxidative stress, aging, and cancer has not been well studied. Human diploid fibroblasts (HDFs) undergo premature senescence in response to sublethal doses of H(2)O(2). To test the hypothesis that senescent or senescent-like HDFs function as a tumor promoter, we have employed an in vitro skin tumor promotion model, in which colony formation is measured using initiated mouse keratinocyte 308 cells seeded at clonal density. 308 cells form colonies when co-cultured with normal HDFs only in the presence of the tumor promoter phorbol 12-myristate 13-acetate (TPA), which induces an average of 5.75 colonies. When co-cultured with H(2)O(2)-treated HDFs, 308 cells form an average of 30.3 colonies. To understand the mechanism behind this phenomenon, we tested whether conditioned medium of HDFs, HDF extracellular matrix (ECM), density of HDFs, or the contact between keratinocytes and HDFs plays a role in 308 cell colony formation. The conditioned medium from prematurely senescent cells resulted in an average of eightfold more 308 cell colonies formed than the conditioned medium from normal HDFs, and the growth-promoting effect of the conditioned medium was trypsin sensitive. The ECM alone was not able to induce 308 cell colony formation. Increasing the density of normal HDFs or contact with normal HDFs but not senescent-like HDFs was inhibitory to the growth of 308 cells. Measurement of Connexin 43 indicated a decreased expression of the protein, which suggests an impaired gap junction communication in senescent-like HDFs. We conclude that H(2)O(2)-treated fibroblasts not only lose contact inhibition of the growth of initiated keratinocytes perhaps related to reduced gap junction communication but also increase production of secreted protein factors to enhance the growth of 308 keratinocytes.
- Chen, Y. -., Purdom, S., & Chen, Q. -. (2003). Linking oxidative stress and genetics of aging with p66Shc signaling and forkhead transcription factors. Biogerontology, 4(4).More infoGenetics versus oxidative stress have been long-standing points of contention among theories seeking to explain the root of aging. Because aging is the highest risk factor for many diseases, it is to our advantage to better understand the biological mechanisms of this process. Caloric restriction has been the only reliable means of extending lifespan in mammalian models until recently. The discovery of mutant strains of mice with increased longevity could be a significant contributor to our understanding of the genetic and molecular basis of human aging. One genetic approach that increases the longevity of mice is the removal of the p66Shc gene, which encodes a protein belonging to a family of adaptors for signal transduction in mitogenic and apoptotic responses. Normally, p66Shc is tyrosine phosphorylated (activated) by various extracellular signals including EGF and insulin. However, serine phosphorylation of p66Shc can occur after oxidative stress either in association with or independently of tyrosine phosphorylation. p66Shc serine phosphorylation has been linked to inactivation of members of forkhead transcription factors, resulting in increased intracellular oxidant levels and increased sensitivity to apoptosis. Knocking out p66Shc allows moderately elevated activity of forkhead transcription factors and better-equipped antioxidant defenses at the cellular level. Recent reports have suggested that methylation of the p66Shc promoter has important implications in its expression regulation. This leads us to hypothesize that the methylation status of the p66Shc promoter may differ between individuals and therefore contribute to variations of longevity. We present evidence arguing that decreasing oxidative stress or increasing resistance to oxidative damage as a result of genetic variation or p66Shc knockout is likely contributing to individual differences in longevity.
- Chen, Y. -., Purdom, S., & Chen, Q. -. (2003). p66(Shc): at the crossroad of oxidative stress and the genetics of aging. Trends in molecular medicine, 9(5).More infoThe biology of aging has been mysterious for centuries. Removal of the p66(Shc) gene, which encodes an adaptor protein for cell signaling, extends lifespan by approximately 30% in mice and confers resistance to oxidative stress. The absence of p66(Shc) correlates with reduced levels of apoptosis. Oxidants induce phosphorylation of serine36 on p66(Shc), contributing to inactivation of members of the Forkhead transcription factor family, some of which appear to regulate the expression of antioxidant genes. The expression of p66(Shc) is regulated by the methylation status of its promoter. This leads us to hypothesize that increased methylation of the p66(Shc) promoter might contribute to the absence of its expression and therefore extended longevity in particular individuals.
- Chen, Y. -., Tu, V. C., Bahl, J. J., & Chen, Q. -. (2003). Distinct roles of p42/p44(ERK) and p38 MAPK in oxidant-induced AP-1 activation and cardiomyocyte hypertrophy. Cardiovascular toxicology, 3(2).More infoCardiac hypertrophy is an adaptive response to a number of heart diseases including myocardial infarction. Although it can be compensatory at first, sustained hypertrophy is often a transition to heart failure. We have found that cardiomyocytes in culture can survive mild doses of H2O2 but develop hypertrophy involving activation of p70 S6 kinase 1 (p70S6K1). Here, the role of p42/p44(ERK) and p38 MAPK in oxidant-induced hypertrophy is tested. H2O2- induced phosphorylation (activation) of p42/p44(ERK) and p38 within 10 min of 200 microM H2O2 exposure. Although p42/p44(ERK) remained highly phosphorylated from 60 to 120 min, the level of p38 phosphorylation reached highest at 60 min and started to decline at 90 min. Inhibiting ERKs with PD98059 attenuated H2O2-induced AP-1 activation but did not affect H2O2-induced p70S6K1 activation or cardiomyocyte enlargement as measured by increases in cell volume and protein content. In contrast, the p38 inhibitor SB202190 has no inhibitory effect on AP-1 activation but partially prevented H2O2 from inducing p70S6K1 activation and cell enlargement. These data suggest that while p42/p44(ERK) participates in gene expression associated with hypertrophy, p38 may regulate cell size increase by p70S6K1 activation.
- Chen, Y. -., Tu, V. C., Bahl, J. J., & Chen, Q. -. (2002). Signals of oxidant-induced cardiomyocyte hypertrophy: key activation of p70 S6 kinase-1 and phosphoinositide 3-kinase. The Journal of pharmacology and experimental therapeutics, 300(3).More infoCardiomyocytes in culture can survive low or mild doses of oxidants but later increase cell volume and protein content. To understand the mechanism, we determined the early signaling events of oxidative stress. With 200 microM H2O2, the activity of p70 S6 kinase-1 (p70S6K1) increased at 30 min and reached a plateau at 90 min. Dose-response studies at the 60 min time point show that p70S6K1 activity reached its highest level with 150 microM H2O2. Increased p70S6K1 activity correlated with phosphorylation of Thr389 and Thr421/Ser424 residues, suggesting the involvement of an upstream kinase. Phosphoinositide 3-kinase (PI3K) activity was elevated by 5 min, reached a plateau at 10 min, and remained more than 6-fold induced for at least 60 min after 200 microM H2O2 exposure. The dose-response studies at 10 min found that 150 microM H2O2 induced the highest PI3K activity. Increased PI3K activity correlated with tyrosine phosphorylation of the 85-kDa regulatory subunit. Inactivating PI3K with wortmannin prevented H2O2 from inducing Thr389 phosphorylation and p70S6K1 activation. Wortmannin and rapamycin prevented H2O2 from inducing increases in cell volume and protein content. The antineoplastic drugs doxorubicin and daunorubicin also induced significant enlargement of cardiomyocytes at 10 to 100 nM dose range. Although the glutathione synthesis inhibitor buthionine sulfoximine potentiated the effect of doxorubicin and H2O2, the antioxidant N-acetylcysteine prevented induction of cell enlargement. Our data suggest that oxidative stress induces activation of PI3K, which leads to p70S6K1 activation and enlargement of cell size.
- Chen, Q., & Chen, Q. -. (2000). Replicative senescence and oxidant-induced premature senescence. Beyond the control of cell cycle checkpoints. Annals of the New York Academy of Sciences, 908.More infoNormal human diploid fibroblasts (HDFs) undergo replicative senescence inevitably in tissue culture after a certain number of cell divisions. A number of molecular changes observed in replicative senescent cells occur in somatic cells during the process of aging. Genetic studies on replicative senescence indicate the control of tumor suppression mechanisms. Despite the significance of replicative senescence in aging and cancer, little is known about the central cause of the complex changes observed in replicative senescent cells. The interest in the phenomenon has intensified in recent years, since damaging agents, certain oncogenes and tumor suppressor genes have been found to induce features of senescence in early passage young HDFs or in immortalized tumor cells. The reported features of senescence are summarized here in order to clarify the concept of replicative senescence or premature senescence. The experimental results of extending the replicative life span by reducing ambient oxygen tension or by N-tert-butyl-alpha-phenylnitrone (PBN) argue a role of oxidative damage in replicative senescence. By inducing premature senescence with a pulse treatment of H2O2, we can study the role of the cell cycle checkpoint proteins p53, p21, p16 and Rb in gaining each feature of senescence. Although p53 and Rb control G1 arrest and Rb appears to control cell enlargement, activation of the senescent associate beta-galactosidase, loss of cell replication and multiple molecular changes observed in premature senescent or replicative senescent cells are likely controlled by mechanisms beyond the cell cycle checkpoints.
- Chen, Q. (2019, Aug). Translational Control of Nrf2 for Tissue Protection. 2019 RNA Symposium. Tucson: Department of Molecular and Cellular Biology, University of Arizona.
- Chen, Q. (2019, Dec). Nrf2 for Cardiac Protection: The Complexity of Human Genome, Disease and Aging. Sarver Heart Center Seminar. Sarver Heart Center, Arizona Health Science Center.
- Chen, Q. (2019, Feb). Translational Control of Oxidative Stress: Nrf2 for Cardiac Protection. The Ames Symposium. Oakland Children's Hospital Research Institute: Oxygen Club of California.
- Chen, Q. (2019, March). Nrf2 for Cardiac Protection: Rev Up the Defense Within. Department of Physiology Seminar, University of Mississippi Medical Center. Jackson, MS: Department of Physiology Seminar, University of Mississippi Medical Center.
- Chen, Q. (2019, May). Translational Control of Oxidative Stress: Nrf2 at the heart of cytoprotection. Environmental Toxicology Program, University of Georgia. Athens: School of Veterinary Medicine, University of Georgia.
- Chen, Q. (2019, Oct). Nrf2 for Cardiac Protection: The Complexity of Human Genome. Moscow Cardiology Congress. Moscow: Moscow State University of Medicine.
- Chen, Q. (2018, April). The Bright and Dark Side of Nrf2 for Tissue Protection. 2018 Experimental Biology Meeting Symposium. San Diego: American Society of Pharmacology and Experimental Therapeutics.
- Chen, Q. (2018, Feb). Translational Control of Oxidative Stress: Nrf2 at the heart of cytoprotection against environmental pollution. Departmental Seminar. Davis, University of California.
- Chen, Q. (2018, June). Translational Control of Oxidative Stress: novel mechanisms of Nrf2 for cytoprotection. College Seminar. University of Connecticut College of Pharmacy, Storrs.
- Chen, Q. (2018, May). Translational Control of Oxidative Stress: Nrf2 at the heart of cytoprotection. Graduate student seminar. Florida State University, Tallahassee.
- Chen, Q. (2018, Oct). Digitizing Human Genome for Effective Pharmacological Therapy. 2018 World Life Science Congress. Beijing, China.
- Chen, Q. (2018, Oct). The Evolvement in Pharmacological Treatment of Myocardial Infarction. 6th Meeting on Acute Cardiology and Emergency Medicine. University of Vilnius, Lithuania.
- Chen, Q. (2017, July). Oxidative Stress Induces Cellular Hypertrophy: Role of Protein Translation and Retinoblastoma Gene. The 25th International Symposia on Morphological Sciences. Xi'an, China.
- Chen, Q. (2017, Oct). Drugs for Cardiac Protection. 12th International Congress on Innovations in Coronary Artery Disease. Venice, Italy: European Society of Cardiology, Italian Society of Cardiology.
- Chen, Q. (2017, Sept). Molecular Biology of Oxidative Stress and Its Role in Heart Function. Moscow Cardiology Congress. Moscow, Russia: Russian National Department of Health and Moscow State University of Medicine and Dentistry.
- Chen, Q. (2016, May). Cardiovascular Translation Medicine: From the Basic Science Laboratory to the Bedside. 5th Meeting on Intensive and Invasive Cardiology. Vilnius, Lithuania: Lithuanian Society of Cardiology, European Society of Cardiology, Acute Cardiovascular Care Association.
- Chen, Q. (2016, November). 3-D Printing for Pharmacological Therapies. World Life Sciences Conference. Beijing: World Life Science Association.
- Chen, Q. (2016, Oct). De Novo Protein Synthesis Mechanisms during Arsenic Stress. The 9th Conference on Metal Toxicity and Carcinogenesis. Lexington, Kentucky: University of Kentucky, NIEHS.
- Chen, Q., & Alpert, J. (2016, November). Digital Medicine: Impact on Medical Practice. Shandong Digital Medicine Conference. Jinan, China.
- Chen, Q. (2015, March). Translational Control of Oxidative Stress. Society of Toxicology Annual Meeting. San Diego: Society of Toxicology.
- Chen, Q. (2015, November). Molecular Mechanims of Myocardial Protection: Role of Nrf2 and Exosomes. 11th International Congress on Coronary Artery Diseases. Florence, Italy: International Congress on Coronary Artery Diseases.More infoAims: Oxidative stress plays an important role in mitochondrial decay and cardiac injury. The paradox is that low to mild doses of oxidative stress activate endogenous defense mechanisms, including Nrf2, a transcription factor regulating the expression of a number of antioxidant and detoxification genes. In experimental animals, we found that knocking out Nrf2 gene results in an increase in cardiac injury due to myocardial ischemia, and loss of preconditioning induced cardiac protection. We address whether Nrf2 plays a role in protecting mitochondria and whether there is a role of extracellular vesicles in cardiac injury or protection.Methods: A combination of cellular and molecular biology techniques were used to determine mitochondrial morphology, mitochondrial function, mitochondrial protein expression, localization of Nrf2 protein and extracellular vesicle secretion.Results: Normally, mitochondria in cardiomyocytes exist in elaborated networks. Following oxidative stress, mitochondria show individual punctuate morphology with disorganized cristae and area of condensation in surviving cardiomyocytes. Mitochondrial protein expression decreases in company with decreased functionality. Nrf2 overexpression prevents oxdiants from inducing mitochondria morphological changes or decline in mitochondrial function. Interestingly, Nrf2 protein was found to associate with the outer mitochondrial membrane. Mitochondria prepared from the myocardium of Nrf2 knockout mice are more sensitive to permeability transition. Conclusions: Our finding of Nrf2 association with mitochondria provides an additional mechanism for the cardiac protective funciton of Nrf2 gene.
- Chen, Q., & Strom, J. (2015, November). Role of Statins for Cardiac Protection: Basic Mechanisms. 11th International Congress on Coronary Artery Disease. Florence, Italy: International Congress on Coronary Artery Diseases.More infoAims: The discovery of statin drugs has dramatically reduced the incidence of atherosclerosis. Statins have been marketed as inhibitors of HMG-CoA reductase, the rate-limiting enzyme that catalyzes HMG-CoA to mevalonic acid in the biosynthesis of cholesterol, therefore reducing cholesterol and LDL levels in the blood. In recent years, statins have been found to exhibit pleiotropic effects beyond cholesterol-lowering. We investigate the cardiac protective effect of statins independent of cholesterol lowering.Methods: Literature review, review of clinical trials, animal and cell culture studies.Results: Clinical trials have demonstrated that acute administration of statins in patients suffering a myocardial infarct results in reduced morbidity and mortality independent of cholesterol-lowering effects. A retrospective study of 13 clinical trials has demonstrated that administration of high doses of statins as a pretreatment to percutaneous coronary intervention (PCI) reduced periprocedural myocardial infarction and 30 days major adverse cardiac events by 46%. We have found that acute statin administration reduces infarct size in a surgical model of myocardial infarction independent of dyslipidemia in rodents. We have found that statins induce cytoprotective genes in the myocardium and cells in culture.Conclusion: The short time frame of the therapeutic benefit observed with statin administration in myocardial infarct patients is inconsistent with the time course for cholesterol lowing effect. Induction of cytoprotective genes in the experimental animals and at the cellular level is important for mediating the cardiac protective effect of statins.