A selective Cullin 3 RING E3 ligase inhibitor attenuates hyperglycemia via dual insulin sensitizing and insulinotropic action

Hyperglycemia is a hallmark of type-2 diabetes and a key pathogenic driver of diabetic complications. Cullin RING E3 ligases (CRLs) are multi-subunit E3 ubiquitin ligases that mediate cellular protein turnover. The activity of CRLs requires cullin neddylation, a post-translational modification that can be pharmacologically targeted with therapeutic potentials. By using hyperinsulinemic-euglycemic clamp analysis, we discover that pan neddylation inhibitor exerts both insulin sensitization effect in liver and muscle and insulinotropic effect in pancreatic β cells. This dual action is mediated by Cullin 3 (Cul3), a member of the 7 canonical cullin family proteins. DI-1859, a selective Cul3 neddylation inhibitor, effectively protects against hyperglycemia in obese mice. DI-1859 enhances insulin signaling by preventing Cul3-mediated insulin receptor substrate degradation in liver and muscle cells. DI-1859 increases insulin secretion in a glucagon-like peptide-1-independent manner in mice and directly potentiates glucose-stimulated insulin secretion in INS-1 832/13 β cells and human islets. Mechanistic studies reveal that DI-1859 does not promote glycolytic flux or bioenergetics function but potentiates glucose-stimulated insulin secretion via mechanisms involving RhoA activation and cytoskeleton remodeling in β cells. This study shows that a single agent targeting Cul3 neddylation simultaneously promotes insulin sensitization and insulin secretion to attenuate hyperglycemia in mice. Article Highlights: a. Pan cullin neddylation inhibitors exhibit potent hypoglycemic effect.b. The target organs and mechanisms underlying the hypoglycemia effect of cullin pan neddylation inhibitors are incompletely understood.c. We found that inhibition of Cul3 leads to a dual insulin sensitization and insulinotropic effect.d. Selective inhibition of Cul3 neddylation is a feasible approach to lower hyperglycemia.