NADPH oxidase NOX1 is involved in activation of protein kinase C and premature senescence in early stage diabetic kidney

Free Radic Biol Med. 2015 Jun;83:21-30. doi: 10.1016/j.freeradbiomed.2015.02.009. Epub 2015 Feb 18.

Abstract

Increased oxidative stress and activation of protein kinase C (PKC) under hyperglycemia have been implicated in the development of diabetic nephropathy. Because reactive oxygen species derived from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, NOX1 accelerate the translocation of PKC isoforms, NOX1 is postulated to play a causative role in the development of diabetic nephropathy. Hyperglycemia was induced in wild-type and Nox1-deficient mice (KO) by two doses of streptozotocin injection. At 3 weeks after the induction of hyperglycemia, glomeruli and cortical tubules were isolated from kidneys. The mRNA level of Nox1 was significantly upregulated in the renal cortex at 3 weeks of hyperglycemia. Urinary albumin and expression of inflammatory or fibrotic mediators were similarly elevated in diabetic wild-type and KO; however, increases in glomerular volume and mesangial matrix area were attenuated in diabetic KO. Nox1 deficiency significantly reduced the levels of renal thiobarbituric acid-reacting substances and 8-hydroxydeoxyguanosine, membranous translocation of PKCα/β, activity of PKC, and phosphorylation of p38 mitogen-activated protein kinase in the diabetic kidney. Furthermore, increased staining of senescence-associated β-galactosidase in glomeruli and cortical tubules of diabetic mice was significantly suppressed in KO. Whereas the levels of cyclin-dependent kinase inhibitors, p16(INK4A) and p21(Cip1), were equivalent between the genotypes, increased levels of p27(Kip1) and γ-H2AX, a biomarker for DNA double-strand breaks, were significantly attenuated in isolated glomeruli and cortical tubules of diabetic KO. Taken together, NOX1 modulates the p38/p27(Kip1) signaling pathway by activating PKC and promotes premature senescence in early stage diabetic nephropathy.

Keywords: Diabetic nephropathy; Free radicals; NADPH oxidase; NOX1; Protein kinase C; Senescence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Cells, Cultured
  • Cellular Senescence / physiology*
  • Diabetes Mellitus, Experimental / chemically induced
  • Diabetes Mellitus, Experimental / metabolism
  • Diabetes Mellitus, Experimental / pathology*
  • Diabetic Nephropathies / chemically induced
  • Diabetic Nephropathies / metabolism
  • Diabetic Nephropathies / pathology*
  • Glomerular Mesangium / metabolism
  • Glomerular Mesangium / pathology*
  • Hyperglycemia / chemically induced
  • Hyperglycemia / metabolism
  • Hyperglycemia / pathology*
  • Immunoenzyme Techniques
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • NADH, NADPH Oxidoreductases / physiology*
  • NADPH Oxidase 1
  • Oxidation-Reduction
  • Oxidative Stress
  • Protein Kinase C / genetics
  • Protein Kinase C / metabolism*
  • RNA, Messenger / genetics
  • Reactive Oxygen Species / metabolism
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction
  • beta-Galactosidase / metabolism
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • RNA, Messenger
  • Reactive Oxygen Species
  • NADH, NADPH Oxidoreductases
  • NADPH Oxidase 1
  • NOX1 protein, mouse
  • Protein Kinase C
  • p38 Mitogen-Activated Protein Kinases
  • beta-Galactosidase