26-LB: Systemic Inhibition of MicroRNA-451 Impairs Renal Autophagy Process in a Mouse Model of Insulin Resistance and Early Diabetic Nephropathy

Abstract

Diabetic nephropathy (DN) is a severe complication of diabetes mellitus and a common cause of end stage renal disease (ESRD). Novel effective therapies are needed to combat disease progression. Several studies suggest a renal protective role of microRNA-451 (miR-451) in ameliorating progression of DN. However, the role of miR-451 in DN is not understood. Defects in the autophagy process has been associated with DN. The current study aimed to elucidate the role of miR-451 in the development of DN in a mouse model of insulin resistance. Male TALLYHO/Jng mice were placed on a high-fat diet (60% kCal) and divided into two treatment groups. Mice were injected (intraperitoneal) once a week for 8-weeks with locked nucleic acid (LNA) miR-451 inhibitor or LNA-scramble (2mg/kg/bw; n=8/treatment). Mice were humanely euthanized after 12 weeks and kidneys harvested. LNA-miR-451 inhibitor significantly reduced renal expression of miR-451 by 6-fold. Collagen deposition was higher in inhibitor treated mice, as revealed by Masson’s Trichrome. Period Acid Schiff did not reveal significant glomerular damage between the two groups. Kidney weight (normalized to body weight) was significantly higher in the inhibitor treated mice. Western blotting analyses of cortex homogenates revealed increased expression of markers of renal injury, KIM1 and NGAL (p<0.05), in inhibitor treated mice. The expression of fibrotic signaling molecules mTOR, AMPKα, and TGF-β was significantly higher in the inhibitor treated group. The expression of autophagy markers SQSTM1/p62 and Beclin-1 was higher and lower, respectively, in inhibitor treated mice (p<0.05). The findings of this study suggest that reduced expression of miR-451 in DN impairs autophagy response in the kidney possibly via hyperactivation of the mTOR-signaling pathway. miR-451 may confer protection against DN by targeting key components of the autophagy process in the diabetic kidney. Disclosure M.B. Fluitt: None. N. Shivapurkar: None. L. Li: None. C.M. Ecelbarger: None. Funding American Diabetes Association (1-18-PMF-002 to M.B.F.); National Institutes of Health (TL1TR001431)