In this proposal we will determine the role of Ras GTPase-activating protein (RasGAP) in regulating microRNA-1 (miR-1) during cardiac hypertrophy. MiR-1 is a post- transcriptional regulator of gene expression that is acutely down-regulated upon induction of hypertrophy by work overload, growth factors, or RasGAP, an outcome that is necessary for myocyte growth. Our preliminary data show that RasGAP SH3-binding protein (G3BP) binds miR-1 in a RasGAP- and Akt-dependent manner. We hypothesize that hypertrophic stimuli induce Akt-mediated G3BP phosphorylation and its subsequent recruitment by RasGAP-filamin complex. This brings it into close proximity to miR-1, where it binds and hydrolyzes premature miR-1. Subsequently, down-regulation of miR- 1 results in upregulation of its targets that include: RasGAP, Cdk9, fibronectin, endothelin, and insulin-like growth factor, among others. These genes play a critical role in the development of cardiac hypertrophy. Thus, our Aims are: 1) to study the mechanism of RasGAP-mediated down-regulation of miR-1 during myocyte hypertrophy. For this aim we will utilize cultured myocytes in conjunction with recombinant cDNA, adenoviruses, and promoter constructs, using stretch as a hypertrophic stimulus to: a. examine the role of G3BP in post-transcriptional regulation of miR-1, b. examine the role of Akt in RasGAP-G3BP-regulated miR-1 stability, c. examine the role of filamin-C in recruitment of RasGAP-G3BP, d. examine the effect of hypertrophy and the RasGAP- activated pathway on transcriptional vs. post-transcriptional regulation of miR-1.
Aim 2) to study the role of RasGAP and miR-1 during cardiac hypertrophy in a mouse model.

Public Health Relevance

MicroRNA are newly discovered regulators of gene expression in the heart. They provide potentially promising therapeutic targets in cardiovascular diseases as they do in cancer. But first it is necessary to identify their gene targets and understand the mechanism of their regulation and function. In this proposal we will investigate the mechanism of regulation of miR-1 by Ras GTPase activating protein and its role in induction of cardiac hypertrophy.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
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Adhikari, Bishow B
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Rutgers University
Anatomy/Cell Biology
Schools of Medicine
United States
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Sayed, Danish; He, Minzhen; Yang, Zhi et al. (2013) Transcriptional regulation patterns revealed by high resolution chromatin immunoprecipitation during cardiac hypertrophy. J Biol Chem 288:2546-58
Han, Mingyue; Yang, Zhi; Sayed, Danish et al. (2012) GATA4 expression is primarily regulated via a miR-26b-dependent post-transcriptional mechanism during cardiac hypertrophy. Cardiovasc Res 93:645-54
Abdellatif, Maha (2012) Sirtuins and pyridine nucleotides. Circ Res 111:642-56
Abdellatif, Maha (2012) Differential expression of microRNAs in different disease states. Circ Res 110:638-50
Han, Mingyue; Toli, Jessica; Abdellatif, Maha (2011) MicroRNAs in the cardiovascular system. Curr Opin Cardiol 26:181-9
Rane, Shweta; He, Minzhen; Sayed, Danish et al. (2010) An antagonism between the AKT and beta-adrenergic signaling pathways mediated through their reciprocal effects on miR-199a-5p. Cell Signal 22:1054-62
Sayed, Danish; He, Minzhen; Hong, Chull et al. (2010) MicroRNA-21 is a downstream effector of AKT that mediates its antiapoptotic effects via suppression of Fas ligand. J Biol Chem 285:20281-90
Abdellatif, Maha (2010) The role of microRNA-133 in cardiac hypertrophy uncovered. Circ Res 106:16-8
Rane, Shweta; He, Minzhen; Sayed, Danish et al. (2009) Downregulation of miR-199a derepresses hypoxia-inducible factor-1alpha and Sirtuin 1 and recapitulates hypoxia preconditioning in cardiac myocytes. Circ Res 104:879-86
Sayed, Danish; Rane, Shweta; Lypowy, Jacqueline et al. (2008) MicroRNA-21 targets Sprouty2 and promotes cellular outgrowths. Mol Biol Cell 19:3272-82

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