Introduction and Objective: Mitochondrial Rho-GTPase (MIRO1) is a critical regulator of mitochondrial trafficking and calcium homeostasis and by extension, mediates cellular energy balance and intracellular signaling. This study aimed to mechanistically decipher the role of MIRO1 in modulating skeletal muscle insulin action, which has been completely unexplored.Methods: Skeletal muscle MIRO1 KO mice (MIRO1MKO) and littermate controls were generated by crossing MIRO1-floxed mice with Acta1-Cre transgenic mice. 8-week-old animals were maintained at thermoneutrality and fed a high fat diet for 16 weeks to induce metabolic stress. Following dietary intervention, insulin sensitivity was assessed in vivo by insulin tolerance test (ITT) and skeletal muscle was insulin stimulated ex vivo to analyze insulin signaling protein targets. Additionally, C2C12 myoblasts with shRNA-mediated MIRO1 knockdown were utilized to evaluate glucose uptake and insulin signaling pathways.Results: MIRO1MKO mice exhibited increased insulin tolerance relative to littermate controls (p<0.01). Skeletal muscle sections from MIRO1MKO mice displayed increased GLUT4 localization at the cell surface under both basal (p<0.001) and insulin-stimulated conditions (p<0.05), accompanied by increased Akt phosphorylation at Thr308 (pAktThr308) (p<0.01). Consistent with these findings, shRNA-mediated MIRO1 knockdown increased glucose uptake (p<0.01) and GLUT4 content (p<0.01) at the plasma membrane in C2C12 myoblasts.Conclusion: MIRO1 plays a critical role in mediating skeletal muscle insulin action. Collectively, these data indicate that MIRO1 acts as a negative regulator of glucose homeostasis desensitizing skeletal muscle insulin action.
A.L. Taylor: None. E.C. Heintz: None. E.R. Zunica: None. B. Vandanmagsar: None. W.S. Dantas: None. P. Baumgarten: None. K. Belmont: None. C.L. Axelrod: None. J.P. Kirwan: None.
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