Discerning L-type trafficking modulation by targeted excision of ubiquitin and SUMO

PROJECT SUMMARY The enclosed application outlines the research and career development plans designed to facilitate the successful transition of the principal investigator, Dr. Sri Karthika Shanmugam, to an independent academic position through the K99/R00 award. Dr. Shanmugam has a multidisciplinary background, and through this K99/R00 proposal, seeks to finalize her cardiovascular training, master the biology of a new regulatory system, and gain skills for her career as an independent investigator. The K99 phase of this award involves a structured career development plan that will allow Dr. Shanmugam to: advance her skills in cardiac contractility experiments on the cellular level using freshly isolated murine myocytes as well as in vivo experiments on the organism level by echocardiography; gain essential training in SUMO- based trafficking and functional experiments; and acquire important career skills such as grant writing, science communication, lab management, teaching and mentorship, responsible conduct of research, and mastery of the academic job application process. The career development plan also includes clear and actionable steps for identifying and successfully obtaining an independent tenure-track faculty position by the end of the K99 phase. Dr. Shanmugam has assembled a top-tier team of multi-disciplinary mentors, advisors, and collaborators that will oversee and guide her training, research program, and transition to independence. The research program for the K99 phase focuses on mechanistic and functional studies of the cardiac L-type CaV1.2 trafficking regulation mediated by enDUBs that are designed to excise specific ubiquitin linkage chains from the channel. The R00 research program then aims to employ the mechanistic information and technical skills gained in the K99 phase to study novel CaV1.2 trafficking regulatory pathways modulated by SUMO and SUMO-ubiquitin signaling crosstalk. Core research questions addressed include: What is the role of ubiquitin and SUMO in regulating CaV1.2 channel forward and reverse trafficking? What are the molecular determinants of these regulatory mechanisms? How do these mechanisms impact cardiac function? To answer these questions, Dr. Shanmugam has formed a comprehensive research plan combining state-of- the-art technology including flow-cytometry, digly-proteomics, ion channel electrophysiology, membrane protein biochemistry and cellular biology. It involves the detailed study of trafficking dynamics and function of CaV1.2 channels; interrogation of the link between ubiquitin and SUMO; and evaluating cardioprotective abilities of enDUBs using a heart failure model. This research will provide key insights into CaV1.2 trafficking mechanisms mediated by ubiquitin and SUMO in the heart, which will accelerate targeted treatments for heart diseases. The proposed studies will take place at Columbia University, which is abode to a vibrant community of physiologists, biophysicists, and biochemists. This environment is ideal to promote the successful completion of Dr. Shanmugam’s proposed K99 research program and transition into an independent researcher.