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.
The process of islet amyloid formation activates cellular stress pathways leading to ?-cell death and type 2 diabetes. We propose to examine apoptosis repressor with a caspase recruitment domain (ARC), a novel protein in the islet ?-cell that restrains pro-death molecules in these pathways, and thus could prevent ?-cell apoptosis. By gaining a greater understanding of the role of proteins linked to the death and survival of the ?- cell, our ultimate goal is to develop new approaches to preserve ?-cells and thereby prevent or treat diabetes.
| Templin, Andrew T; Meier, Daniel T; Willard, Joshua R et al. (2018) Use of the PET ligand florbetapir for in vivo imaging of pancreatic islet amyloid deposits in hIAPP transgenic mice. Diabetologia 61:2215-2224 |
| Templin, Andrew T; Samarasekera, Tanya; Meier, Daniel T et al. (2017) Apoptosis Repressor With Caspase Recruitment Domain Ameliorates Amyloid-Induced ?-Cell Apoptosis and JNK Pathway Activation. Diabetes 66:2636-2645 |
| Hogan, Meghan F; Meier, Daniel T; Zraika, Sakeneh et al. (2016) Inhibition of Insulin-Degrading Enzyme Does Not Increase Islet Amyloid Deposition in Vitro. Endocrinology 157:3462-8 |
| Meier, Daniel T; Entrup, Leon; Templin, Andrew T et al. (2016) The S20G substitution in hIAPP is more amyloidogenic and cytotoxic than wild-type hIAPP in mouse islets. Diabetologia 59:2166-71 |
