Caveolae are specialized microdomains of the plasma membrane that are abundant in the cells of the heart. In cardiomyocytes, a variety of signaling molecules and ion channels have been localized to caveolae, including Cav1.2-encoded voltage-gated L-type Ca2+ channels (LTCCs). Mutations in the gene encoding caveolin-3 (CAV3), an essential structural component of caveolae in cardiomyocytes, are causative in long-QT syndrome (LQTS), which is an arrhythmia syndrome that is a leading cause of sudden cardiac death. Recently we found that two LQTS-linked caveolin-3 (Cav3) mutations, F97C and S141R, promote distinct, mutation-specific gain-of-function effects on the L-type Ca2+ current (ICa,L) that mathematical modeling predicts are critical for action potential duration (APD) prolongation in LQTS. These findings provide the first evidence that LQTS-linked Cav3 mutations alter ICa,L, yet the precise molecular mechanisms underlying augmented ICa,L in the context of disparate LQTS-linked Cav3 mutations, as well as the normal composition of caveolar LTCC complexes and basis for Cav3-mediated regulation of ICa,L, remain poorly understood. Thus, elucidating the composition of caveolar LTCC complexes and molecular basis for Cav3-mediated regulation of ICa,L, as well as changes in the context of distinct LQTS-linked Cav3 mutations, will be the focus of the proposed studies. Although the study of caveolar constituents and their dynamics has traditionally been difficult, herein, we propose to employ quantitative proteomics with in situ protein labeling using engineered ascorbate peroxidase 2 (APEX2) to study these specialized microdomains in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). hiPSC-CMs are a powerful model for studying human cardiac biology and disease, and have already been used to study LQTS. The proposed studies will aid elucidation of the caveolar proteome, mechanisms of caveolar ion channel regulation, and may yield insight into the molecular mechanisms of arrhythmias towards the development of novel therapeutic strategies to reduce the risk of sudden cardiac death.
|Program type||Postdoctoral Fellowship|
|Effective start/end date||01/01/2020 → 12/31/2021|