1091-OR: Impaired Skeletal Muscle Insulin Signaling Drives MIRO1 Accumulation and Defective Mitochondrial AKT Translocation

Introduction and Objective: Aberrant skeletal muscle mitochondrial dynamics exacerbates insulin resistance in type 2 diabetes (T2D). Mitochondrial Rho-GTPase (MIRO1) mediates mitochondrial trafficking and metabolite signaling, but its role in skeletal muscle insulin action remains unknown. In this study, we investigated whether impaired insulin signaling disrupts mitochondrial AKT translocation via MIRO1. Methods: Patients with or without T2D underwent hyperinsulinemic-euglycemic clamps with vastus lateralis biopsies obtained pre- and post-insulin infusion. Mitochondria were isolated and immunoblotted for MIRO1, pAKTThr308, and total AKT. C2C12 myoblasts treated ± insulin were analyzed for MIRO1 and AKT expression and colocalization by immunofluorescence. Cells were treated with MK-2206 (AKT inhibitor), insulin, or both to examine AKT-dependent regulation of MIRO1. Gastrocnemius from 30-week-old C57BL/6J mice was stimulated ± insulin for co-immunoprecipitation of MIRO1 and AKT. Results: Skeletal muscle from patients with T2D exhibited defective mitochondrial AKT translocation in response to insulin, accompanied by failure of insulin to suppress MIRO1 expression. In C2C12 cells, insulin decreased MIRO1 expression concomitant with increased mitochondrial AKT. Insulin increased AKT-MIRO1 colocalization. Co-immunoprecipitation revealed direct binding between MIRO1 and AKT in mouse skeletal muscle mitochondria. Inhibition of AKT with MK-2206 led to MIRO1 accumulation under insulin-stimulated conditions. Conclusion: Impaired insulin-AKT signaling causes MIRO1 accumulation, disrupting mitochondrial AKT translocation and exacerbating skeletal muscle insulin resistance. Disclosure A.L. Taylor: None. E. Heintz: None. E.R. Zunica: None. B. Vandanmagsar: None. C. Axelrod: None. J.P. Kirwan: Consultant; Current; Eli Lilly and Company. Research Support; Current; Eli Lilly and Company. Advisory Panel; Ended; Novo Nordisk. Funding National Institutes of Health (DK108089)