Targeting Protein Trafficking in Arrhythmogenic Cardiomyopathy

ABSTRACT This proposal is to support the career development of Joseph Palatinus, MD, PhD, to become an independent physician scientist with a focus on basic/translational research by targeting protein trafficking as a means to prevent and treat arrhythmias and sudden cardiac death (SCD). The PI will have as a primary mentor Professor Robin Shaw, MD PhD, who is world renowned expert in protein trafficking and cardiomyocyte biology. The comprehensive training program is composed of laboratory-based research, coursework, workshops, grantsmanship seminars, scientific conferences (local and international), and career guidance by a mentoring committee. The committee includes the mentors and leverages the combined experience and technical knowledge of 5 leading independent cardiovascular investigators at the Eccles Cardiovascular Research and Training Institute at the University of Utah as well as Dr. Jeffery Saffitz at Harvard Medical School, a world expert on Arrhythmogenic cardiomyopathy. The research proposed will apply the alternatively translated isoform of Connexin 43 (Cx43), dubbed GJA1-20k (and an established actin stabilizing protein), to the Desmoglein 2 (DSG2) mutant model of ACM. Preliminary data has demonstrated disrupted actin organization in both cellular and animal models of a DSG2 mutation which, in the heart is associated with a loss of gap junction trafficking to the intercalated disk and downstream cardiac dysfunction. It is hypothesized that GJA1-20k will lead to recovery of gap junction localization, suppression of arrhythmias and prevention of SCD in the DSG2 mutant model of ACM by directly interacting with and stabilizing cellular actin. Two specific aims are proposed: 1) Is actin dysregulation responsible for the trafficking defects observed in the DSG2 mutant model? And 2) Does GJA1- 20k rescue the cardiomyopathic and arrhythmogenic phenotype of ACM and prevent SCD? High resolution confocal microscopy, proximity ligation immunolabeling, electron microscopy, co- immunoprecipitation, echocardiography, and in vivo telemetry monitoring are some of the advanced techniques which will be used to develop a mechanistic understanding of actin dependent trafficking mediated by GJA1-20k. The results from this study are expected to develop a novel paradigm to treat and prevent arrhythmogenic SCD by targeting protein trafficking.