1146-OR: Dual Insulin-Sensitizing and Insulinotropic Actions of a Selective Cullin 3 Neddylation Inhibitor Attenuate Hyperglycemia

Introduction and Objective: Hyperglycemia is a hallmark of type 2 diabetes (T2D) and a key driver for diabetic complications. Cullin Ring E3 Ligases (CRLs) are the largest family of multi-subunit ubiquitin E3 ligases, and their activation requires cullin neddylation, a process that covalently links the ubiquitin-like protein NEDD8 to the cullin scaffold. While pan-neddylation inhibitors have shown promise in mitigating obesity and metabolic dysfunction, the specific cullins mediating their metabolic benefits remain unknown. This study aimed to identify the specific cullin responsible for the antihyperglycemic effects of neddylation inhibition. Methods: We used pan-neddylation inhibitors (MLN4924, TAS4464) and a selective Cullin 3 inhibitor (DI-1859). Whole-body insulin sensitivity was assessed using hyperinsulinemic-euglycemic clamp analysis in obese mice. Tissue-specific effects were evaluated using in vitro glucose uptake assays in myotubes and glucose-stimulated insulin secretion (GSIS) assays in INS-1 832/13 β cells and human islets. Results: Pan-neddylation inhibitors exert potent hypoglycemic effects in obese mice by enhancing insulin sensitivity in liver and muscle and promoting pancreatic insulin secretion. This dual action is mediated by Cullin 3 (Cul3), a member of the seven canonical cullin family. Mechanistically, Cul3 inhibition prevents insulin receptor substrate (IRS) degradation, thereby prolonging insulin signaling and reducing hepatic glucose production and enhancing muscle glucose uptake. Furthermore, in β cells and human islets, Cul3 inhibition significantly enhances glucose-stimulated insulin secretion. Consistently, we show that a selective Cul3 inhibitor enhances insulin signaling and secretion and lowers blood glucose in obese mice. Conclusion: These findings suggest that targeting Cul3 neddylation may represent a therapeutic strategy with dual insulin-sensitizing and insulinotropic effects for T2D treatment. Disclosure L. Gu: None. L. Xiong: None. M.N. Hasan: None. Y. Du: None. T.Y. Wu: None. T. Li: None. Funding National Institutes of Health (1R01DK134316 and 5R01DK131064).