Abstract 910: Identification of Novel Cardiac Sarcomere Interactions Using BioID Proximity-labeling

• Published in: Circulation research 2019-08, Vol.125 (Suppl_1)
• Main Authors: PETTINATO, Anthony M, Ladha, Feria, Thakar, Ketan, Hinson, Travis
• Format: Article
• Language: English
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/res.125.suppl_1.910

Abstract only Mutations in components of the sarcomere, the contractile unit of cardiomyocytes, are a leading cause of genetic cardiomyopathies, such as dilated cardiomyopathy (DCM), which is an important contributor to heart failure burden. Using human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), our work has previously shown that DCM-causing mutations in titin, a major structural and functional component of the sarcomere, lead to diminished cardiac force production and impaired sarcomerogenesis. A classical model of sarcomerogenesis suggests that sarcomere assembly begins with pre-myofibrils containing beaded Z-disks composed of alpha-actinin, actin, and non-muscle myosin, with further assembly marked by addition of muscle myosin and titin. Once assembled, sarcomeres exhibit linear Z-disks and distinct protein markers. We are interested in understanding this stepwise process by probing sarcomere protein-protein interactions, with the objective of identifying novel developmental mediators and structural components of the sarcomere. More specifically, we would like to identify proteins that interact or localize near alpha-actinin at the Z-disk of the sarcomere. To do this, we have combined CRISPR/Cas9 genome-editing with BioID proximity-labeling to produce isogenic iPSC-CMs that express alpha-actinin fused with BirA, a promiscuous biotin ligase that biotinylates vicinal proteins. We have also generated a sarcomere-deficient iPSC-CM model that can readily reform sarcomeres on-demand, which we will use to further understand stage-specific interactions of sarcomere structure and development. Our results will not only provide novel insights into human sarcomere biology, but may also uncover novel targets for heart failure drug development.