The Role of Apoptosis Repressor with Caspase Recruitment Domain (ARC) in Amyloid-Induced Beta-cell Apoptosis

University Of Washington, Seattle WA

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Abstract

? DESCRIPTION (provided by applicant): Islet amyloid formation is a hallmark of type 2 diabetes that is associated with ?-cell apoptosis and loss of ?-cell mass. Prior studies have determined that c-Jun N-terminal kinase (JNK), Bcl-2-associated death promoter (Bad), and Bcl-2-associated X protein (Bax) have important pro-apoptotic roles in amyloid-induced ?- cell apoptosis. Conversely, the role of a novel anti-apoptotic protein that was recently identified in the ?-cell, apoptosis repressor with caspase recruitment domain (ARC), is not well understood. Therefore, I propose to study ARC's role in amyloid-induced ?-cell apoptosis. The goal of this work is to gain knowledge of ARC which will lead to novel strategies to prevent ?-cell loss, a critical component of the development of type 2 diabetes. I propose a model whereby ARC antagonizes the actions of three well-known pro-apoptotic proteins in the ?-cell, namely JNK, Bad and Bax. I posit that under normal conditions, ARC represses JNK activation and sequesters Bad and Bax. In the setting of amyloid formation, ARC no longer represses JNK activation, and is unable to sequester Bad and Bax, leading to ?-cell apoptosis. In this application I propose three specific aims to address this hypothesis. Specific Aim 1: Determine whether the anti-apoptotic effect of ARC in the ?-cell is mediated in part by inhibition of JNK pathway activation. Specific Aim 2: Determine whether ARC sequestration of Bad and Bax contributes to its anti-apoptotic effect in the ?-cell. Specific Aim 3: Determine whether ARC overexpression improves hIAPP transgenic islet graft survival following islet transplantation. I will use islets from a transgenic mouse model of islet amyloid, wild type mouse islets, and an immortalized ?-cell line to perform the proposed studies. This three-year plan is a comprehensive training proposal focused on scientific and professional development objectives. Studies will expand the current understanding of ?-cell apoptosis, while facilitating the acquisition of new skills such as adenoviral transduction of islets, immunohistochemistry, quantitative microscopy, proximity ligation assay, and islet transplantation. Dr. Kahn's scientific direction, laboratory capabilities, and commitment to exceptional mentoring will contribute to the successful completion of this project, and to my career development. Participation in seminars, lab meetings, journal club, regional and national meetings, and research events sponsored by the University of Washington Diabetes Research Center (DRC) will contribute to a comprehensive training and career development experience. Together, these activities will enable me to successfully compete for a Career Development (K) Award and progress towards my goal of becoming an independent investigator of islet biology.