- Associate Professor, Animal and Comparative Biomedical Sciences
- Associate Professor, BIO5 Institute
Ravi Goyal received his Ph.D. in pharmacology from the University of Mississippi and MD from Armed Forces Medical College, India. He completed his post-doctoral fellowship at Loma Linda University.
Dr. Goyal joined the University of Arizona as an Associate Professor in the School of Animal and Comparative Biomedical Sciences and Bio5 Research Institute in 2018. He was also inducted as a member of University Arizona Cancer Center. Previously, he worked at the Department of Basic Sciences, School of Medicine, Loma Linda University as an Associate Professor from 2016-2018, Assistant Professor from 2009 to 2016, and Postdoctoral Research Associate from 2008-2009.
He has served on several review panels of National Institute of Health, American Heart Association, and Switzerland National Science Foundation. He also serves on the editorial board of Biomed Central and Frontiers in Science Journals. His research has been funded by the National Institute of Child Health and Disease and National Heart, Lung, and Blood Institute.
Dr. Goyal has taught Evidence-Based Medicine, Neuroscience, Pharmacology, Physiology, Advanced Bioinformatics, and Advanced Biotechnology Research and Methods courses from last 15 years.
He has expertise in epigenetic programming of vascular function and development, stem cell differentiation, and development of targeted cancer therapy. Other projects included the development of gene therapy to convert adipose-derived stem cells in insulin-secreting cells as well as developing a suicide gene therapy to target cancer cells.
The major approaches the group use to investigate angiogenesis, stem cell differentiation, and development of targeted cancer therapeutics are aimed at the identification of the novel transcripts including long non-coding RNA involved in these processes. These transcriptomic regions are then examined with contemporary bioinformatic methods to identify conserved regions in the mouse, sheep, and human genome. Following identification of the conserved region, we use the CRISPR technique to knockdown or activate these regions to determine their functional implications. We hope to identify molecular targets by which we can increase or decrease angiogenesis, improve stem cells differentiation efficiency and provide a targeted approach to kill cancer cells.
The significant contribution of Goyal’s group is providing evidence that balanced nutrition and optimal oxygenation is vital for a healthier life of the offspring and prevention of diseases in adult life. Specifically, the group has demonstrated that despite adequate calories, protein malnutrition during pregnancy can lead to lifelong consequences in the offspring. Furthermore, they have shown that this programming occurs at the epigenetic level and can be inheritable. Other contributions include hypoxia-mediated alterations of gene expression in arterial contractility and angiogenesis. Currently, the group is investigating the role of long non-coding RNA on angiogenesis and vascular development. Dr. Goyal’s lab group has published several peer-reviewed original research articles, reviews, and book chapters on cardiovascular and cerebrovascular changes in response to maternal stress.
- Ph.D. Pharmacology
- The University of Mississppi, Oxford, Mississippi, United States
- M.D. Internal Medicine
- Armed Forces Medical College, Pune, India
- The University of Arizona (2018 - Ongoing)
- Loma Linda University (2016 - 2018)
- Loma Linda University (2009 - 2016)
- Loma Linda University (2007 - 2009)
Licensure & Certification
- FAHA, American Heart Association (2019)
Mechanisms regulating angiogenesis;Gene Therapy;Epigenetic Regulation of Fetal Development
Bioinformatics, Pharmacology, Physiology, Molecular Biology, Genetics and Epigenetics
Honors ThesisACBS 498H (Spring 2021)
Independent StudyACBS 599 (Spring 2021)
Prin Anml Genetic SystemACBS 313 (Spring 2021)
ResearchMCB 900 (Spring 2021)
ThesisACBS 910 (Spring 2021)
ThesisMCB 910 (Spring 2021)
Honors ThesisACBS 498H (Fall 2020)
Psio of ReproductionACBS 315R (Fall 2020)
ResearchMCB 900 (Fall 2020)
Research SeminarACBS 696A (Fall 2020)
ThesisMCB 910 (Fall 2020)
Honors Independent StudyACBS 399H (Spring 2020)
Independent StudyACBS 599 (Spring 2020)
Prin Anml Genetic SystemACBS 313 (Spring 2020)
Molecular EndocrinologyACBS 587 (Fall 2019)
Research SeminarACBS 696A (Fall 2019)
- Goyal, D., & Goyal, R. (2019). Angiogenic Transformation in Human Brain Micro Endothelial Cells: Whole Genome DNA Methylation and Transcriptomic Analysis. Frontiers in physiology, 10, 1502.More infoWe tested the hypothesis that endothelial capillary tube formation in 3D cultures in basement membrane extract (BME) is secondary to the altered DNA promoter methylation and mRNA expression in human brain micro endothelial cells (HBMECs). We conducted a whole-genome transcriptomic and methylation microarray and CRISPR/Cas9-mediated gene knockdown to test our hypothesis. The data demonstrated that with angiogenic transformation 1318 and 1490 genes were significantly ( < 0.05) upregulated and downregulated, respectively. We compared our gene expression data with the published databases on GEO and found several genes in common. PTGS2, SELE, ID2, HSPA6, DLX2, HEY2, FOSB, SMAD6, SMAD7, and SMAD9 showed a very high level of expression during capillary tube formation. Among downregulated gene were ITGB4, TNNT1, PRSS35, TXNIP, IGFBP5. The most affected canonical pathways were ATM signaling and cell cycle G2/M DNA damage checkpoint regulation. The top upstream regulators of angiogenic transformation were identified to be VEGF, TP53, HGF, ESR1, and CDKN1A. We compared the changes in gene expression with the change in gene methylation and found hypomethylation of the CpG sites was associated with upregulation of 515 genes and hypermethylation was associated with the downregulation of 31 genes. Furthermore, the silencing of FOSB, FZD7, HEY2, HSPA6, NR4A3, SELE, PTGS2, SMAD6, SMAD7, and SMAD9 significantly inhibited angiogenic transformation as well as cell migration of HBMECs. We conclude that the angiogenic transformation is associated with altered DNA methylation and gene expression changes.
- Goyal, D., Limesand, S. W., & Goyal, R. (2019). Epigenetic responses and the developmental origins of health and disease. The Journal of endocrinology, 242(1), T105-T119.More infoMaternal and paternal factors influence offspring development and program its genome for successful postnatal life. Based on the stressors during gestation, the pregnant female prepares the fetus for the outside environment. This preparation is achieved by changing the epigenome of the fetus and is referred to as 'developmental programming'. For instance, nutritional insufficiency in utero will lead to programming events that prepare the fetus to cope up with nutrient scarcity following birth; however, offspring may not face nutrient scarcity following birth. This discrepancy between predicted and exposed postnatal environments are perceived as 'stress' by the offspring and may result in cardiovascular and metabolic disorders. Thus, this developmental programming may be both beneficial as well as harmful depending on the prenatal vs postnatal environment. Over the past three decades, accumulating evidence supports the hypothesis of Developmental Origin of Health and Disease (DOHaD) by the programming of the fetal phenotype without altering the genotype per se. These heritable modifications in gene expression occur through DNA methylation, histone modification and noncoding RNA-associated gene activation or silencing, and all are defined as epigenetic modifications. In the present review, we will summarize the evidence supporting epigenetic regulation as a significant component in DOHaD.
- Yates, D. T., Camacho, L. E., Kelly, A. C., Steyn, L. V., Davis, M. A., Antolic, A. T., Anderson, M. J., Goyal, R., Allen, R. E., Papas, K. K., Hay, W. W., & Limesand, S. W. (2019). Postnatal β2 adrenergic treatment improves insulin sensitivity in lambs with IUGR but not persistent defects in pancreatic islets or skeletal muscle. The Journal of physiology, 597(24), 5835-5858.More infoPrevious studies in fetuses with intrauterine growth restriction (IUGR) have shown that adrenergic dysregulation was associated with low insulin concentrations and greater insulin sensitivity. Although whole-body glucose clearance is normal, 1-month-old lambs with IUGR at birth have higher rates of hindlimb glucose uptake, which may compensate for myocyte deficiencies in glucose oxidation. Impaired glucose-stimulated insulin secretion in IUGR lambs is due to lower intra-islet insulin availability and not from glucose sensing. We investigated adrenergic receptor (ADR) β2 desensitization by administering oral ADRβ modifiers for the first month after birth to activate ADRβ2 and antagonize ADRβ1/3. In IUGR lambs ADRβ2 activation increased whole-body glucose utilization rates and insulin sensitivity but had no effect on isolated islet or myocyte deficiencies. IUGR establishes risk for developing diabetes. In IUGR lambs we identified disparities in key aspects of glucose-stimulated insulin secretion and insulin-stimulated glucose oxidation, providing new insights into potential mechanisms for this risk.
- Ducsay, C. A., Goyal, R., Pearce, W. J., Wilson, S., Hu, X. Q., & Zhang, L. (2018). Gestational Hypoxia and Developmental Plasticity. Physiological reviews, 98(3), 1241-1334.More infoHypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.
- Goyal, D., & Goyal, R. (2018). Developmental Maturation and Alpha-1 Adrenergic Receptors-Mediated Gene Expression Changes in Ovine Middle Cerebral Arteries. Scientific reports, 8(1), 1772.More infoThe Alpha Adrenergic Signaling Pathway is one of the chief regulators of cerebrovascular tone and cerebral blood flow (CBF), mediating its effects in the arteries through alpha1-adrenergic receptors (Alpha1AR). In the ovine middle cerebral artery (MCA), with development from a fetus to an adult, others and we have shown that Alpha1AR play a key role in contractile responses, vascular development, remodeling, and angiogenesis. Importantly, Alpha1AR play a significant role in CBF autoregulation, which is incompletely developed in a premature fetus as compared to a near-term fetus. However, the mechanistic pathways are not completely known. Thus, we tested the hypothesis that as a function of maturation and in response to Alpha1AR stimulation there is a differential gene expression in the ovine MCA. We conducted microarray analysis on transcripts from MCAs of premature fetuses (96-day), near-term fetuses (145-day), newborn lambs, and non-pregnant adult sheep (2-year) following stimulation of Alpha1AR with phenylephrine (a specific agonist). We observed several genes which belonged to pro-inflammatory and vascular development/angiogenesis pathway significantly altered in all of the four age groups. We also observed age-specific changes in gene expression-mediated by Alpha1AR stimulation in the different developmental age groups. These findings imply complex regulatory mechanisms of cerebrovascular development.
- Siebold, L., Obenaus, A., & Goyal, R. (2018). Criteria to define mild, moderate, and severe traumatic brain injury in the mouse controlled cortical impact model. Experimental neurology, 310, 48-57.More infoTraumatic brain injury (TBI) is a major health concern in the United States resulting in a substantial number of hospitalizations and in a broad spectrum of symptoms and disabilities. In the clinical setting, neurological responsiveness and structural imaging are used to classify mild, moderate and severe TBI. To evaluate the complex secondary and severity-specific injury response, investigators have relied on pre-clinical rodent models. The controlled cortical impact (CCI) model in mice is a widely used to study TBI. The CCI method has demonstrated consistent intra-laboratory outcomes due to precise control of cortical depth penetration, dwell time and speed of impact. While the CCI method results in control of injury severity, there is no consensus regarding the injury parameters or behavioral and histological endpoints that constitute a mild, moderate or severe TBI in this model. This discrepancy has resulted in considerable variability across laboratories in the outcomes of CCI-induced mild, moderate, and severe TBI. Inconsistent with clinical evaluation, injury severity in the CCI model has predominately relied on the extent of tissue damage. In the present review, we discuss variations in surgical parameters for injury induction as well as the criteria used to determine injury severity. Additionally, we propose guiding principles for the induction and defining of mild, moderate and severe TBI in the craniectomy-dependent experimental mouse CCI model.
- Goyal, R., & Clyman, R. I. (2017). Response to Coceani et al. Pediatric research, 82(2), 175.
- Kumar, M. M., & Goyal, R. (2017). LncRNA as a Therapeutic Target for Angiogenesis. Current topics in medicinal chemistry, 17(15), 1750-1757.More infoOut of 3 billion base pairs in human genome only ~2% code for proteins; and out of 180,000 transcripts in human cells, about 20,000 code for protein, remaining 160,000 are non-coding transcripts. Most of these transcripts are more than 200 base pairs and constitute a group of long non-coding RNA (lncRNA). Many of the lncRNA have its own promoter, and are well conserved in mammals. Accumulating evidence indicates that lncRNAs act as molecular switches in cellular differentiation, movement, apoptosis, and in the reprogramming of cell states by altering gene expression patterns. However, the role of this important group of molecules in angiogenesis is not well understood. Angiogenesis is a complex process and depends on precise regulation of gene expression.
- Mata-Greenwood, E., Goyal, D., & Goyal, R. (2017). Comparative and Experimental Studies on the Genes Altered by Chronic Hypoxia in Human Brain Microendothelial Cells. Frontiers in physiology, 8, 365.More infoHypoxia inducible factor 1 alpha (HIF1A) is a master regulator of acute hypoxia; however, with chronic hypoxia, HIF1A levels return to the normoxic levels. Importantly, the genes that are involved in the cell survival and viability under chronic hypoxia are not known. Therefore, we tested the hypothesis that chronic hypoxia leads to the upregulation of a core group of genes with associated changes in the promoter DNA methylation that mediates the cell survival under hypoxia. We examined the effect of chronic hypoxia (3 days; 0.5% oxygen) on human brain micro endothelial cells (HBMEC) viability and apoptosis. Hypoxia caused a significant reduction in cell viability and an increase in apoptosis. Next, we examined chronic hypoxia associated changes in transcriptome and genome-wide promoter methylation. The data obtained was compared with 16 other microarray studies on chronic hypoxia. Nine genes were altered in response to chronic hypoxia in all 17 studies. Interestingly, HIF1A was not altered with chronic hypoxia in any of the studies. Furthermore, we compared our data to three other studies that identified HIF-responsive genes by various approaches. Only two genes were found to be HIF dependent. We silenced each of these 9 genes using CRISPR/Cas9 system. Downregulation of EGLN3 significantly increased the cell death under chronic hypoxia, whereas downregulation of ERO1L, ENO2, adrenomedullin, and spag4 reduced the cell death under hypoxia. We provide a core group of genes that regulates cellular acclimatization under chronic hypoxic stress, and most of them are HIF independent.
- Giang, M., Papamatheakis, D. G., Nguyen, D., Paez, R., Blum Johnston, C., Kim, J., Brunnell, A., Blood, Q., Goyal, R., Longo, L. D., & Wilson, S. M. (2016). Muscarinic Receptor Activation Affects Pulmonary Artery Contractility in Sheep: The Impact of Maturation and Chronic Hypoxia on Endothelium-Dependent and Endothelium-Independent Function. High altitude medicine & biology, 17(2), 122-32.More infoGiang, Michael, Demosthenes G. Papamatheakis, Dan Nguyen, Ricardo Paez, Carla Blum Johnston, Joon Kim, Alexander Brunnell, Quintin Blood, Ravi Goyal, Lawrence D. Longo, and Sean M. Wilson. Muscarinic receptor activation affects pulmonary artery contractility in sheep: the impact of maturation and chronic hypoxia on endothelium-dependent and endothelium-independent function. High Alt Med Biol. 17:122-132, 2015.-Muscarinic receptor activation in the pulmonary vasculature can cause endothelium-dependent vasodilation and smooth muscle-dependent vasoconstriction. Chronic hypoxia (CH) can modify both of these responses. This study aimed to assess the combined influence of CH and maturation on endothelium-dependent and endothelium-independent muscarinic-induced vasoreactivity. This was accomplished by performing wire myography on endothelium-intact or endothelium-disrupted pulmonary arterial rings isolated from normoxic or CH fetal and adult sheep. In endothelium-intact arteries, vasodilation was evaluated using cumulative bradykinin doses in phenylephrine and carbachol precontracted pulmonary arterial segments; and vasoconstriction was examined using cumulative doses of carbachol following bradykinin predilation. Effects of nonselective (atropine) and selective M1 (pirenzepine), M2 (AFDX116), and M3 (4-DAMP and Dau5884) muscarinic receptor antagonists were assessed in disrupted arteries. In normoxic arteries, bradykinin relaxation was twofold greater in the adult compared to fetus, while carbachol contraction was fourfold greater. In adult arteries, CH increased bradykinin relaxation and carbachol contraction. In vessels with intact endothelium, maturation and CH augmented maximal response and efficacy for carbachol constriction and bradykinin relaxation. Approximately 50%-80% of adult normoxic and CH endothelium-disrupted arteries contracted to acetylcholine, while ∼50% of fetal normoxic and ∼10% of CH arteries responded. Atropine reduced carbachol-induced contraction in all vessels. Adult normoxic vessels were most responsive to M3 antagonism, fetal to M2 antagonism, while M1 inhibition had no effect. Overall, muscarinic-induced pulmonary arterial contraction is partially endothelium dependent and appears to develop after birth. Fetuses are more reliant on M3 receptors while M2 receptors predominate in adults, whereas CH augments muscarinic-dependent pulmonary vasoconstriction in both.
- Goyal, R., Billings, T. L., Mansour, T., Martin, C., Baylink, D. J., Longo, L. D., Pearce, W. J., & Mata-Greenwood, E. (2016). Vitamin D status and metabolism in an ovine pregnancy model: effect of long-term, high-altitude hypoxia. American journal of physiology. Endocrinology and metabolism, 310(11), E1062-71.More infoVitamin D status increases during healthy mammalian pregnancy, but the molecular determinants remain uncharacterized. The first objective of this study was to determine the effects of pregnancy, and the second objective was to examine the role of chronic hypoxia on vitamin D status and metabolism in an ovine model. We analyzed the plasma levels of cholecalciferol, 25-OH-D, and 1α,25-(OH)2D in nonpregnant ewes, near-term pregnant ewes, and their fetuses exposed to normoxia (low altitude) or hypoxia (high-altitude) for 100 days. Hypoxic sheep had increased circulating levels of 25-OH-D and 1α,25-(OH)2D compared with normoxic sheep. Hypoxia increases in 25-OH-D were associated with increased expression of renal 25-hydroxylases CYP2R1 and CYP2J. Pregnancy did not increase further the plasma levels of 25-OH-D, but it significantly increased those of the active metabolite, 1α,25-(OH)2D, in both normoxic and hypoxic ewes. Increased bioactivation of vitamin D correlated with increased expression of the vitamin D-activating enzyme CYP27b1 and decreased expression of the inactivating enzyme CYP24a1 in maternal kidneys and placentas. Hypoxia increased parathyroid hormone levels and further increased renal CYP27b1. Pregnancy and hypoxia decreased the expression of vitamin D receptor (VDR) in maternal kidney and lung, with opposite effects on placental VDR. We conclude that ovine pregnancy is a model of increased vitamin D status, and long-term hypoxia further improves vitamin D status due to pregnancy- and hypoxia-specific regulation of VDR and metabolic enzymes.
- Goyal, R., Goyal, D., Longo, L. D., & Clyman, R. I. (2016). Microarray gene expression analysis in ovine ductus arteriosus during fetal development and birth transition. Pediatric research, 80(4), 610-8.More infoPatent ductus arteriosus (PDA) in the newborn is the most common congenital heart anomaly and is significantly more common in preterm infants. Contemporary pharmacological treatment is effective in only 70-80% of the cases. Moreover, indomethacin or ibuprofen, which are used to close a PDA may be accompanied by serious side effects in premature infants. To explore the novel molecular pathways, which may be involved in the maturation and closure of the ductus arteriosus (DA), we used fetal and neonatal sheep to test the hypothesis that maturational development of DA is associated with significant alterations in specific mRNA expression.
- Goyal, R., & Longo, L. D. (2015). Metabolic Profiles in Ovine Carotid Arteries with Developmental Maturation and Long-Term Hypoxia. PloS one, 10(6), e0130739.More infoLong-term hypoxia (LTH) is an important stressor related to health and disease during development. At different time points from fetus to adult, we are exposed to hypoxic stress because of placental insufficiency, high-altitude residence, smoking, chronic anemia, pulmonary, and heart disorders, as well as cancers. Intrauterine hypoxia can lead to fetal growth restriction and long-term sequelae such as cognitive impairments, hypertension, cardiovascular disorders, diabetes, and schizophrenia. Similarly, prolonged hypoxic exposure during adult life can lead to acute mountain sickness, chronic fatigue, chronic headache, cognitive impairment, acute cerebral and/or pulmonary edema, and death.
- Goyal, R., Van-Wickle, J., Goyal, D., & Longo, L. D. (2015). Antenatal maternal low protein diet: ACE-2 in the mouse lung and sexually dimorphic programming of hypertension. BMC physiology, 15, 2.More infoElevated blood pressure is an important global health problem, and in-utero under-nutrition may be an important factor in the pathogenesis of hypertension. In the present study, we tested the hypothesis that antenatal maternal low protein diet (MLPD) leads to sexually dimorphic developmental programming of the components of the pulmonary renin-angiotensin system. This may be important in the antenatal MLPD-associated development of hypertension. In pregnant mice, we administered normal (control) and isocaloric 50% protein restricted diet, commencing one week before mating and continuing until delivery of the pups. From the 18th to 24th week postnatal, we measured blood pressure in the offspring by use of a non-invasive tail-cuff method. In the same mice, we examined the mRNA and protein expression of the key components of the pulmonary renin-angiotensin system. Also, we examined microRNA complementary to angiotensin converting enzymes (ACE) 2 in the offspring lungs. Our results demonstrate that as a consequence of antenatal MLPD: 1) pup birthweight was significantly reduced in both sexes. 2) female offspring developed hypertension, but males did not. 3) In female offspring, ACE-2 protein expression was significantly reduced without any change in the mRNA levels. 4) miRNA 429, which has a binding site on ACE-2 - 3' UTR was significantly upregulated in the female antenatal MLPD offspring. 5) In males, ACE-2 mRNA and protein expression were unaltered. We conclude that in the mouse, antenatal MLPD-induced reduction of ACE-2 in the female offspring lung may be an important mechanisms in sexually dimorphic programming of hypertension.
- Jang, E. A., Longo, L. D., & Goyal, R. (2015). Antenatal maternal hypoxia: criterion for fetal growth restriction in rodents. Frontiers in physiology, 6, 176.More infoRodents are a useful model for life science research. Accumulating evidence suggests that the offspring of mice and rats suffer from similar disorders as humans when exposed to hypoxia during pregnancy. Importantly, with antenatal hypoxic exposure, human neonates demonstrate low birth weight or growth restriction. Similarly, with antenatal hypoxic exposure rodents also demonstrate the fetal growth restriction (FGR). Surprisingly, there is no consensus on the minimum duration or degree of hypoxic exposure required to cause FGR in rodents. Thus, we have reviewed the available literature in an attempt to answer these questions. Based on studies in rats, birth weight reduction of 31% corresponded to 10th percentile reduction in birth weight curve. With the similar criterion (10th percentile), in mice 3 days or more and in rats 7 days or more of 14% or lower hypoxia administration was required to produce statistically significant FGR.