Cardiac Tissue-Specific Repression of CELF Activity Disrupts Alternative Splicing and Causes Cardiomyopathy

Abstract

Members of the CELF family of RNA binding proteins have been implicated in alternative splicing regulation in developing heart. Transgenic mice that express a nuclear dominant-negative CELF protein specifically in the heart (MHC-CELFΔ) develop cardiac hypertrophy and dilated cardiomyopathy with defects in alternative splicing beginning as early as 3 weeks after birth. MHC-CELFΔ mice exhibit extensive cardiac fibrosis, severe cardiac dysfunction, and premature death. Interestingly, the penetrance of the phenotype is greater in females than in males despite similar levels of dominant-negative expression, suggesting that there is sex-specific modulation of splicing activity. The cardiac defects in MHC-CELFΔ mice are directly attributable to reduced levels of CELF activity, as crossing these mice with mice overexpressing CUG-BP1, a wild-type CELF protein, rescues defects in alternative splicing, the severity and incidence of cardiac hypertrophy, and survival. We conclude that CELF protein activity is required for normal alternative splicing in the heart in vivo and that normal CELF-mediated alternative splicing regulation is in turn required for normal cardiac function.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://mcb.asm.org/.

ACKNOWLEDGMENTS

We thank Donnie Bundman, Thuy Pham, Motoaki Sano, and Gopal Singh for technical assistance, David Ladd for help with the statistical analysis, and Michael Schneider for helpful discussions.

This work was supported by grants from the National Institutes of Health to T.A.C. (RO1HL45653), C.H. (RO1HL22512), and G.T. (RO1AG17899). A.N.L. was supported by a postdoctoral NRSA fellowship from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (5F32AR008618-02) and a Development Grant from the Muscular Dystrophy Association (MDA3812).