High‐fat diet increases p62 and mTOR phosphorylation in diabetic eNOS deficient mice

Diabetic nephropathy is the leading cause of chronic kidney disease and end stage renal disease. Emerging evidence has suggested that dysregulated renal autophagy may contribute to both glomerular and tubulointerstitial damage under diabetic conditions. This study was designed to elucidate the effect of a high‐fat diet on autophagy in eNOS deficient animals with and without hyperglycemia. Six‐week old wild‐type (WT) C57BL/6J and eNOS deficient mice were placed on either a normal diet (ND, 4.5% from fat) or high‐fat diet (HFD, 45% from fat). Two weeks later, half of them were rendered diabetic with alloxan. Animals were maintained on ND or HFD for 5 months post diabetes induction. Kidney damage and autophagy activity were evaluated in diabetic WT and eNOS deficient mice. HFD and diabetes induction in eNOS deficient mice resulted in significantly increased urinary albumin to creatinine ratio, matrix metalloproteinase‐9, and kidney injury molecule‐1. Western blot further indicated a significant increase in autophagy substrate p62 in kidney cortex of diabetic eNOS deficient mice fed with HFD, whereas there was no notable change in p62 expression in WT mice. In addition, mammalian target of rapamycin (mTOR) phosphorylation was increased in diabetic eNOS deficient mice. Taken together, our results suggest that HFD may impair renal autophagy by activating mTOR in diabetic eNOS deficient mice. Support or Funding Information NIH (SC1DK112151), NIH/NCRR /RCMI (8G12MD007602) and (8U54MD007588), and R25GM058268