My laboratory identified serum response factor (SRF), an obligatory cardiogenic transcription factor, as a prominent caspase-3 target in human failing hearts. SRF cleavage led to the generation of a dominant negative transcription factor, SRF-N (N-terminus of SRF). This novel discovery is provocative, and raises the question of potential pathogenic role of SRF-N in cardiac dysfunction. To address this question, we generated multiple independent lines of transgenic mice expressing SRF-N in the heart. Mice with high expression SRF-N showed levels comparable to those in human failing myocardium, and developed a two-stage cardiomyopathy phenotype: adaptive hypertrophy followed by heart failure with dilated cardiomyopathy. This provides a novel mouse model that mimics the progression of human heart disease. Microarray and quantitative PCR (Q-PCR) analyses revealed a significant down regulation of miR-133a in the transgenic hearts, which coincided with a robust up regulation of two likely miR-133a target genes NFATc4 (nuclear factor of activated T cells 4) and CamK22 (Ca2????dependent protein kinase 2) that may determine the cardiac phenotype. These studies underpin the application's central hypothesis that the dominant negative SRF-N directs the onset of cardiac hypertrophy and facilitates the progression to overt heart failure through the up regulation of hypertrophic genes by repressing miR-133a gene. Two main aims are proposed.
The Aim I is to determine the pathogenic impact of SRF-N in intact heart. The mutant mice will be critically evaluated under basal and hemodynamic overload conditions. Analysis in cardiac function, changes in morphology and histology and expression of cardiac remodeling genes at three stages: initiation, development and decompensation of hypertrophy will be assessed. The negative impact of SRF-N will be further determined by comparing among the mice expressing low, intermediate and high levels of SRF-N. We have preliminary data suggesting that the up regulation of pro-hypertrophic NFATc4 and CamK22 genes by repressing miR-133a through SRF-N may be associated with SRF-N-mediated cardiomyopathy.
The Aim II, therefore, is focused on 1) the verification of this SRF-N->miR-133a->NFATc4 and CamK22->hypertrophy signaling pathway;2) by blocking parts of this pathway to see if the mouse phenotype is corrected. The ultimate outcome of the application will be to establish a direct link between the dominant negative SRF-N and the development of heart failure. The novelty includes 1) the demonstration of SRF-N-mediated hypertrophic cardiomyopathy in intact heart;2) the identification of two SRF-dependent enhancers regulating miR-133a expression;and 3) the elucidation of two new miR-133a target genes directing disease progression.
Project narrative: The study is to determine the negative role of the transcription factor SRF-N in intact heart, and to verify the preliminarily identified molecular signaling pathway leading to the SRF-N-mediated cardiac suppression. The genetic-manipulated murine mice are applied.
|Yue, Xiaojing; Lin, Xi; Yang, Tingli et al. (2016) Rnd3/RhoE Modulates Hypoxia-Inducible Factor 1?/Vascular Endothelial Growth Factor Signaling by Stabilizing Hypoxia-Inducible Factor 1? and Regulates Responsive Cardiac Angiogenesis. Hypertension 67:597-605|
|Yang, Xiangsheng; Wang, Tiannan; Lin, Xi et al. (2015) Genetic deletion of Rnd3/RhoE results in mouse heart calcium leakage through upregulation of protein kinase A signaling. Circ Res 116:e1-e10|
|Jie, Wei; Andrade, Kelsey C; Lin, Xi et al. (2015) Pathophysiological Functions of Rnd3/RhoE. Compr Physiol 6:169-86|
|Kim, Eun Young; Zhang, Yi; Beketaev, Ilimbek et al. (2015) SENP5, a SUMO isopeptidase, induces apoptosis and cardiomyopathy. J Mol Cell Cardiol 78:154-64|
|Kim, Eun Young; Zhang, Yi; Ye, Bo et al. (2015) Involvement of activated SUMO-2 conjugation in cardiomyopathy. Biochim Biophys Acta 1852:1388-99|
|Liu, Baohui; Lin, Xi; Yang, Xiangsheng et al. (2015) Downregulation of RND3/RhoE in glioblastoma patients promotes tumorigenesis through augmentation of notch transcriptional complex activity. Cancer Med 4:1404-16|
|Yue, X; Yang, X; Lin, X et al. (2014) Rnd3 haploinsufficient mice are predisposed to hemodynamic stress and develop apoptotic cardiomyopathy with heart failure. Cell Death Dis 5:e1284|
|Wang, Xiaohong; Huang, Wei; Yang, Yang et al. (2014) Loss of duplexmiR-223 (5p and 3p) aggravates myocardial depression and mortality in polymicrobial sepsis. Biochim Biophys Acta 1842:701-11|
|Wang, Xiaohong; Huang, Wei; Liu, Guansheng et al. (2014) Cardiomyocytes mediate anti-angiogenesis in type 2 diabetic rats through the exosomal transfer of miR-320 into endothelial cells. J Mol Cell Cardiol 74:139-50|
|Lin, Xi; Liu, Baohui; Yang, Xiangsheng et al. (2013) Genetic deletion of Rnd3 results in aqueductal stenosis leading to hydrocephalus through up-regulation of Notch signaling. Proc Natl Acad Sci U S A 110:8236-41|
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