Abstract: FR-PO631

Renal-Selective Snx5 Gene Silencing Increases Insulin Resistance and Blood Pressure in Mice

Session Information

Category: Diabetes

  • 501 Diabetes Mellitus and Obesity: Basic - Experimental

Authors

  • Wang, Xiaoyan, George Washington University School of Medicine, Washington, District of Columbia, United States
  • Asico, Laureano D., George Washington University School of Medicine, Washington, District of Columbia, United States
  • Ma, Xiaobo, George Washington University School of Medicine, Washington, District of Columbia, United States
  • Jose, Pedro A., George Washington University School of Medicine, Washington, District of Columbia, United States
  • Villar, Van Anthony M., George Washington University School of Medicine, Washington, District of Columbia, United States
Background

We have reported that sorting nexin 5 (SNX5) plays an important role in the positive regulation of insulin receptor expression and function in cultured renal proximal tubule cells and that renal-selective SNX5 gene silencing increased blood pressure (BP) in WKY rats, via the D1 dopamine receptor (D1R).

Methods

In order to test the hypothesis that renal Snx5 gene silencing increases insulin resistance and BP, we measured BP, blood glucose, serum insulin, urinary insulin excretion, and insulin sensitivity in C57Bl/6J mice treated with a 7-day renal subcapsular infusion of Snx5-siRNA; mock-siRNA was used as control (3 μg/kg/day, n=4/group).

Results

Snx5 siRNA-treated mice had elevated BP (SBP: 119±5.2 vs. 101.5±0.5; DBP: 91.8±7.3 vs. 72±2.3, mm Hg, under pentobarbital anesthesia), non-fasting blood glucose (214±3 vs. 179±8, mg/dl) and fasting serum insulin (1.16±0.17 vs. 0.62±0.04, ng/ml) was increased while urinary excretion of insulin (0.15±0.03 vs 0.55±0.13, ng / mg of creatinine) was decreased. In another set of mice (n=4/group) that urine water/sodium excretion, and creatinine clearance between the two groups. Histologically, SNX5 was mainly located in the apical membrane of proximal tubules, thick ascending limbs of loop of Henle, and distal convoluted tubules. SNX5 colocalized with the insulin receptor β (IR-β), insulin-degrading enzyme (IDE), NHE3, NKCC2 and NCC. Renal protein expression (via immunoblotting) of SNX5 (29±10, % of control), IR-β (50±7) and IDE (57±6) were lesser while renal protein expression of NHE3 (172±29), NaPi2 (223±12), NKCC2 (440±12) and NCC (177±23) were greater in SNX5-depleted mice compared to control mice. Renal protein expressions of α/β/γ-ENaC, Na+K+ATPase, actin, and renal morphology(via H&E staining and brightfield microscopy) were similar in both groups.

Conclusion

Silencing of renal SNX5 expression with siRNA decreased renal IR-β/IDE and increased sodium transporters in proximal and distal nephron segments. These may impair the regulation of renal D1R in insulin metabolism and sodium transport and cause increased BP and insulin resistance in SNX5 depleted mice.

Funding

  • NIDDK Support