Animal and preliminary human studies of adult stem cell therapy for myocardial repair have shown an overall improvement of cardiac function. However, repair of injured myocardium remains a serious challenge. Emerging evidence from in vitro and preclinical studies suggests that ischemic environment including inflammation and oxidative stress, have adverse effects on stem cell function. MicroRNAs (miRNA;20-25 nucleotides), are known to regulate several cellular processes such as proliferation, differentiation, cell metabolism, apoptosis and angiogenesis. The premise of our proposed research is based on preliminary observations that 1) prolonged inflammation impairs tube formation ability of mouse BM-derived EPCs, in vitro 2) miRNA array data from EPCs, in response to inflammatory stimuli, indicates an up-regulation of number of miRNAs related to cell survival/death and angiogenesis with a robust increase in miR-377, 3) myocardial infarction (MI) increased miR-377 expression in the myocardium, circulating EPCs and plasma, 3d post-MI;4) pre-miR-377 transfection in EPCs inhibits protein expression of STK35 (a novel kinase localized in the nucleus), a potential target gene of miR-377, 5) miR- 377-mimics reduced EPC migration and vascular tube formation 6) Furthermore, STK35-knockdown in EPCs reduced HDAC5 phosphorylation and increased GATA2 acetylation (indicating transcriptional repression) and was associated with reduced expression of cytokines and growth factors, and reduced migration and vascular tube formation. 7) Most interestingly, in mouse MI model, intramyocardial transplantation of ex vivo anti-miR-377- transfected EPCs decreased cardiomyocyte apoptosis and infarct size, enhanced neovascularization and LV function and therefore efficient myocardial repair. These data provide convincing evidence that anti-miR-377 therapy might enhance the EPC engraftment and function in myocardial ischemia leading to efficient myocardial repair. Our central hypothesis is that ex vivo miR-377 knockdown and intramyocardial transplantation of EPCs augments their function by stimulating STK35-dependent phosphorylation and nuclear export of HDAC5 leading to increased GATA2-mediated transcription of genes (including cytokines and growth factors) that promote neovascularization and cardiomyocyte viability, thus resulting in efficient myocardial repair after injury. The hypotheses will be tested under the following 3 specific aims: 1) Define the role of miR-377 in EPC biology and function, in vitro 2) Elucidate the molecular mechanisms by which miR-377 regulates STK35-mediated EPC function and 3) Determine the critical role of miR-377 in EPC-mediated myocardial repair, using a mouse model of myocardial infarction.
Cardiac diseases like myocardial infarction (MI) are the major causes of mortality in humans. MicroRNAs play a critical role in the progression of cardiovascular diseases and control biology and function of cardiac cells after injury. Interestingly, injured heart recruits bone-marrow derived endothelial progenitor/stem cells (EPC) for repair. However, it is not known how microRNA-377 (that increases with myocardial ischemia) impairs the benefits provided by progenitor cells in the injured heart. This proposal wil test mechanisms by which microRNA-377 alters EPC function in an injured tissue microenvironment in which these cells are injected and study anti-miR-377 therapy effects on the EPC-mediated repair of myocardial tissue during experimental heart injury.
|Karuppagounder, Vengadeshprabhu; Giridharan, Vijayasree V; Arumugam, Somasundaram et al. (2016) Modulation of Macrophage Polarization and HMGB1-TLR2/TLR4 Cascade Plays a Crucial Role for Cardiac Remodeling in Senescence-Accelerated Prone Mice. PLoS One 11:e0152922|
|Verma, Suresh K; Garikipati, Venkata Naga Srikanth; Krishnamurthy, Prasanna et al. (2016) IL-10 Accelerates Re-Endothelialization and Inhibits Post-Injury Intimal Hyperplasia following Carotid Artery Denudation. PLoS One 11:e0147615|
|Giridharan, Vijayasree V; Quevedo, Joao; Krishnamurthy, Prasanna et al. (2016) Editorial Commentary: miRNA a tiny genetic tool: Key to the puzzle of cardiovascular disease. Trends Cardiovasc Med 26:420-2|
|Suresh Babu, Sahana; Thandavarayan, Rajarajan A; Joladarashi, Darukeshwara et al. (2016) MicroRNA-126 overexpression rescues diabetes-induced impairment in efferocytosis of apoptotic cardiomyocytes. Sci Rep 6:36207|
|Jeyabal, Prince; Thandavarayan, Rajarajan A; Joladarashi, Darukeshwara et al. (2016) MicroRNA-9 inhibits hyperglycemia-induced pyroptosis in human ventricular cardiomyocytes by targeting ELAVL1. Biochem Biophys Res Commun 471:423-9|
|Joladarashi, Darukeshwara; Garikipati, Venkata Naga Srikanth; Thandavarayan, Rajarajan A et al. (2015) Enhanced Cardiac Regenerative Ability of Stem Cells After Ischemia-Reperfusion Injury: Role of Human CD34+ Cells Deficient in MicroRNA-377. J Am Coll Cardiol 66:2214-2226|
|Suresh Babu, Sahana; Joladarashi, Darukeshwara; Jeyabal, Prince et al. (2015) RNA-stabilizing proteins as molecular targets in cardiovascular pathologies. Trends Cardiovasc Med 25:676-83|
|Jeyabal, Prince; Thandavarayan, Rajarajan A; Babu, Sahana Suresh et al. (2015) Enhancer-associated long noncoding RNAs: A novel frontier with new perception in cardiac regeneration. Trends Cardiovasc Med 25:603-5|
|Thandavarayan, Rajarajan A; Giridharan, Vijayasree V; Arumugam, Somasundaram et al. (2015) Schisandrin B prevents doxorubicin induced cardiac dysfunction by modulation of DNA damage, oxidative stress and inflammation through inhibition of MAPK/p53 signaling. PLoS One 10:e0119214|
|Giridharan, Vijayasree V; Thandavarayan, Rajarajan A; Arumugam, Somasundaram et al. (2015) Schisandrin B Ameliorates ICV-Infused Amyloid ? Induced Oxidative Stress and Neuronal Dysfunction through Inhibiting RAGE/NF-?B/MAPK and Up-Regulating HSP/Beclin Expression. PLoS One 10:e0142483|
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