Combining experiments of man and nature to target human insulin resistance

About This Grant

Abstract Insulin resistance is a leading cause of type 2 diabetes (T2D), metabolic-associated steatotic hepatitis (MASH), and cardiovascular disease (CVD). Adipose tissue is a crucial regulator of insulin sensitivity and its dysfunction causes whole-body insulin resistance, in large part through adipokines–secreted proteins that influence the insulin responsiveness and metabolism of distal tissues. This project leverages advances in human proteogenomics to identify and credential novel adipokines impacting metabolic health. From human genetic and functional genomic work accomplished in the previous project period, we identified TNFAIP8 as a putative adipokine that promotes insulin resistance and T2D. Previously TNFAIP8 had only been implicated as a cell autonomous protein regulating autophagy. We hypothesize that TNFAIP8, and other yet-undiscovered adipokines, modulate insulin sensitivity and metabolic disease progression. We propose: 1) Identify and credential novel adipokines by integrating protein quantitative trait loci (pQTLs) for >3,000 serum proteins with Mendelian randomization to infer causality, direction of effect, and metabolic disease mediation. These analyses will be combined with human visceral and subcutaneous adipose tissue proteomic profiles. 2) Program visceral and subcutaneous adipocytes in vitro to evaluate adipokine dysregulation under metabolic stress. We will define transcriptional regulators of adipocyte depot fate and generate isogenic induced subcutaneous and visceral adipocyte cell models. These cells will be profiled for secreted proteins, using a novel intracellular protein biotinylation strategy to systematically identify canonically and non-canonically secreted proteins. 3) Perform in vivo adipose-specific biotinylation and genetic ablation studies to validate adipokines physiologically. We will generate a novel mouse model expressing an adipocyte-specific biotin ligase to enable proteomic identification of secreted adipokines under metabolic disease conditions. Adipocyte-specific Tnfaip8 knockout mice will be assessed for insulin sensitivity using hyperinsulinemic-euglycemic clamps. This research will elucidate the roles of novel adipokines in metabolic diseases, offering new therapeutic targets and advancing our understanding of adipose tissue biology.