Decipher the Function of C2cd4a in Metabolism

Project Summary Type 2 diabetes (T2D) is caused by insulin resistance in peripheral tissues and pancreatic beta-cell dysfunction. Insulin resistance precedes beta-cell failure, and the beta-cell’s inability to keep up with the increased demand of insulin production and secretion leads to glucose intolerance and hyperglycemia. The human C2CD4B-C2CD4A-VPS13C locus harbors a pancreatic beta-cell super-enhancer, and is heavily decorated by T2D risk-associated GWAS SNPs from virtually every ethnic group studied to date. There are only ~20 publications on “C2cd4a” in PubMed, the majority of which are association studies linking this locus to human diabetes susceptibility. Through a multi-omics approach followed by functional analysis in mice, we found that beta cell-specific C2cd4a ablation impairs insulin secretion. In this proposal, through C2cd4a we provide a basis to link exercise-induced hypoglycemia and type 2 diabetes treatment. We will investigate C2cd4a-regulated beta cell function, and build a pathway centered on C2cd4a. Two Aims are envisioned: in Aim 1, we will map the repressor domain using truncated versions of human and mouse C2CD4A, and investigate the mechanism of exercise-induced hypoglycemia in beta cell-specific C2cd4a knockout mice. In Aim 2, we will solidify C2cd4a’s role in the nucleus as a transcription cofactor, acting on promoters and enhancers of key beta cell genes. We will examine the regulation of C2cd4a by a novel intergenic long noncoding RNA. These Aims will advance our understanding of C2cd4a as a human diabetes susceptibility gene, and provide a blueprint to leverage human genetics data into biological insight that will eventually benefit patients.