Role of GLIS3 in Human Pancreatic Beta Cell Generation, Survival and Proliferation

Abstract. Genome-wide association studies have identified numerous genetic variants associated with type 1 and type 2 diabetes mellitus (T1DM and T2DM), many of which might affect genes that are involved in pancreatic β cell function and survival. However, the exact biological functions and the mechanistic nature of these genetic variants remain unclear. Human embryonic stem cells (hESCs), provide, in theory, unlimited resources to generate differentiated cells to study the role of genetic factors in human diseases. Of the diabetes-associated genes identified so far, GLIS3 is the only one (other than insulin) associated with both T1DM and T2DM, and neonatal diabetes mellitus (NDM). Recently, we reported an optimized strategy to efficiently derive GLIS3+ pancreatic β-like cells. Using this platform, we found that loss of GLIS3 causes impaired differentiation toward β cells and increases β cell death. Here, we propose to test the hypothesis that genetic and environmental factors caused loss or reduction of GLIS3 impairs human pancreatic β cell generation, survival, and proliferation in both healthy and disease conditions. In preliminary studies, we have created 2 isogenic T2DM-SNP-hESCs, 2 isogenic NDM-M-hESCs, and 2 isogenic KO (knockout)-hESC lines. In addition, we identified a TGFβ inhibitor that rescues the increased death rate in GLIS3-/- β-like cells. In this proposal, we will systematically study the differentiation of isogenic T2DM-SNP-hESCs, NDM-M-hESCs, and GLIS3-KO-hESCs, exploring the generation, function, and survival of the endocrine cells in the disease conditions. Additionally, we will explore the downstream mechanism of GLIS3. Finally, we will develop approaches to improve β cell survival in T2DM conditions by targeting GLIS3 and its downstream pathways. Toward these goals, the following aims are proposed: Aim 1. Evaluate the impact of GLIS3-associated genetic variants in the generation and survival of human pancreatic β cells both in vitro and in vivo. Aim 2. Decode the molecular mechanism of GLIS3 controlling human pancreatic β cell survival. Aim 3. Rescue T2DM islets survival by targeting GLIS3 and its downstream mechanisms. This proposal will systematically analyze the biological function of GLIS3 and associated variants in human β cell's generation, survival, and proliferation. It will significantly enhance our knowledge of β cell biology, which will pave the road for developing novel therapies for T2DM patients.