Abstract 65: Regulation of Cardiac Hypertrophy and Dilated Cardiomyopathy by CIP
Cardiac hypertrophy is one of the primary responses of the heart to pathophysiological stress. However, the mechanism of the transition from compensative hypertrophic growth to cardiac dilation is poor understood. Recently, we identified a cardiac-specific expressed gene CIP. The expression of CIP is unchanged in hypertrophic heart but significantly down-regulated in dilated hearts, suggesting CIP may play an important role in the transition from cardiac hypertrophy to dilated cardiomyopathy.
We generated CIP knockout mice and found that CIP is dispensable for cardiac development. Interestingly, CIP-null mutant mice developed severe cardiac dilation 4 weeks after TAC (transverse aortic constriction) surgery, while control mice were still at the stage of compensative hypertrophic growth. Echocardiography and histological examinations showed that mutant hearts had enlarged chamber with thinner ventricle wall and decreased cardiac performance compared to controls. The expression of marker genes of cardiac disease, BNP and Myh7, was elevated. Consistently, deletion of CIP in Myh6-CnA transgenic mice result in premature death, displaying severe left ventricle dilation.
Conversely, cardiac-specific CIP overexpression inhibited pressure overload-induced cardiac hypertrophy. CIP transgenic mice exhibit decreased ventricle weight/body weight ratio, decreased cardiomyocyte cross-section area and repressed expression of hypertrophic related marker genes. CIP overexpression also protected the heart from developing cardiac dilation and preserved the cardiac function after prolonged pressure overload.
We performed unbiased microarray assay to document the transcriptome in CIP knockout and control mice which were subjected to pressure overload (TAC). The analysis of Gene Ontology term indicated the Negative Regulation of Apoptosis was down-regulated while the Collagen/Extracellular Structure Organization was up-regulated in CIP-null hearts under TAC condition.
In summary, our studies established CIP as a key regulator of the transition from cardiac hypertrophy to dilated cardiomyopathy. The protective effect of CIP in cardiac remodeling indicates that CIP could become a therapeutic target for cardiac diseases.
Author Disclosures: Z. Huang: 2. Research Grant; Significant; NIH T32 training grant: HL007572 M. Kataoka: None J. Chen: None. D. Wang: 2. Research Grant; Modest; NIH R01: HL116919 .
- © 2014 by American Heart Association, Inc.