Catalase-dependent H2O2 consumption by cardiac mitochondria and redox-mediated loss in insulin signaling.
We have recently demonstrated that catalase content in mouse cardiac mitochondria is selectively elevated in response to high dietary fat, a nutritional state associated with oxidative stress and loss in insulin signaling. Catalase and various isoforms of glutathione peroxidase and peroxiredoxin each catalyze the consumption of H2O2Catalase, located primarily within peroxisomes and to a lesser extent mitochondria, has a low binding affinity for H2O2relative to glutathione peroxidase and peroxiredoxin. As such, the contribution of catalase to mitochondrial H2O2consumption is not well understood. In the current study, using highly purified cardiac mitochondria challenged with micromolar concentrations of H2O2, we found that catalase contributes significantly to mitochondrial H2O2consumption. In addition, catalase is solely responsible for removal of H2O2in nonrespiring or structurally disrupted mitochondria. Finally, in mice fed a high-fat diet, mitochondrial-derived H2O2is responsible for diminished insulin signaling in the heart as evidenced by reduced insulin-stimulated Akt phosphorylation. While elevated mitochondrial catalase content (∼50%) enhanced the capacity of mitochondria to consume H2O2in response to high dietary fat, the selective increase in catalase did not prevent H2O2-induced loss in cardiac insulin signaling. Taken together, our results indicate that mitochondrial catalase likely functions to preclude the formation of high levels of H2O2without perturbing redox-dependent signaling.
Affiliation: Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma.
Paul M
PM
Rindler
Affiliation: Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma.
Angela
A
Cacciola
Affiliation: Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma.
Michael
M
Kinter
Affiliation: Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma Luke-Szweda@omrf.org.
Luke I
LI
Szweda
D000818:Animals; D015153:Blotting, Western; D002374:Catalase / Q000235:genetics* / Q000378:metabolism; D018752:Diet, Fat-Restricted; D059305:Diet, High-Fat; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction
D007004:Hypoglycemic Agents; D007328:Insulin; D009249:NADP; D006861:Hydrogen Peroxide; D002374:Catalase; D051057:Proto-Oncogene Proteins c-akt; D005978:Glutathione; D019803:Glutathione Disulfide
H2O2; catalase; heart; insulin signaling; mitochondria