Talk abstracts

Talk on Friday 01:12-01:24pm submitted by Yotam Blech-Hermoni

CELF1 is necessary for myofibril organization and cardiac morphology during embryonic development

Yotam Blech-Hermoni (Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine), Michael W. Jenkins (Department of Pediatrics, Case Western Reserve University School of Medicine), Oliver Wessely (Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic), Andrea N. Ladd (Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic)

CUG-BP and Elav-like family member 1 (CELF1) is an RNA-binding protein expressed in a variety of tissues, including the embryonic and adult heart, where it is restricted to the cardiomyocytes (the contractile cells). CELF1 regulates alternative pre-mRNA splicing in the nucleus, as well as transcript degradation and translation in the cytoplasm. While it is predominantly cytoplasmic in other embryonic tissues, its expression in skeletal and cardiac muscle cells is predominantly nuclear, and this pattern is conserved from frog to mouse. Upon CELF1 knockdown in cultured chicken primary embryonic cardiomyocytes, we observed a decrease in cell proliferation as well as profound disorganization of myofibrillar structure. While cells continued to beat, sarcomeres shifted from rod-like striations along thick, long fibrils to globular puncta arranged in thin, often web-like, matrices. These effects are accompanied by changes in the splicing patterns of genes involved in contractility and the regulation of cardiac gene expression. Following knockdown of celf1 in frog (Xenopus laevis) embryos, we observed aberrant cardiac morphology (smaller, thicker, and often misshapen hearts). We are using optical coherence tomography – a non-invasive imaging modality – to evaluate changes in cardiac function and 3D structure in both fixed and live embryos. We have demonstrated that frog celf1 can regulate alternative splicing, upon expression in cultured cells, and this activity can be repressed by co-expression of a nuclear-retained dominant negative CELF protein. We will use this dominant negative protein to dissect the involvement of nuclear versus cytoplasmic functions of celf1 in cardiac structure and function during embryonic development.

Keywords: RNA binding protein, CELF1, heart development