PKC-delta-dependent activation of oxidative stress in adipocytes of obese and insulin-resistant mice: role for NADPH oxidase

Am J Physiol Endocrinol Metab. 2005 Feb;288(2):E405-11. doi: 10.1152/ajpendo.00378.2004. Epub 2004 Oct 26.


Oxidative stress is thought to be one of the causative factors contributing to insulin resistance and type 2 diabetes. Previously, we showed that reactive oxygen species (ROS) production is significantly increased in adipocytes from high-fat diet-induced obese and insulin-resistant mice (HF). ROS production was also associated with the increased activity of PKC-delta. In the present studies, we hypothesized that PKC-delta contributes to ROS generation and determined their intracellular source. NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI) reduced ROS levels by 50% in HF adipocytes, and inhibitors of NO synthase (L-NAME, 1 mM), xanthine oxidase (allopurinol, 100 microM), AGE formation (aminoguanidine, 10 microM), or the mitochondrial uncoupler (FCCP, 10 microM) had no effect. Rottlerin, a selective PKC-delta inhibitor, suppressed ROS levels by approximately 50%. However, neither GO-6976 nor LY-333531, effective inhibitors toward conventional PKC or PKC-beta, respectively, significantly altered ROS levels in HF adipocytes. Subsequently, adenoviral-mediated expression of wild-type PKC-delta or its dominant negative mutant (DN-PKC-delta) in HF adipocytes resulted in either a twofold increase in ROS levels or their suppression by 20%, respectively. In addition, both ROS levels and PKC-delta activity were sharply reduced by glucose depletion. Taken together, these results suggest that PKC-delta is responsible for elevated intracellular ROS production in HF adipocytes, and this is mediated by high glucose and NADPH oxidase.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipocytes / drug effects
  • Adipocytes / metabolism*
  • Animals
  • Cells, Cultured
  • Dietary Fats / metabolism
  • Dose-Response Relationship, Drug
  • Enzyme Activation
  • Insulin Resistance*
  • Mice
  • Mice, Inbred C57BL
  • NADPH Oxidases / metabolism*
  • Obesity / metabolism*
  • Onium Compounds / pharmacology
  • Oxidative Stress*
  • Protein Kinase C / metabolism*
  • Protein Kinase C-delta
  • Reactive Oxygen Species / metabolism*


  • Dietary Fats
  • Onium Compounds
  • Reactive Oxygen Species
  • diphenyleneiodonium
  • NADPH Oxidases
  • Prkcd protein, mouse
  • Protein Kinase C
  • Protein Kinase C-delta