High dietary fat selectively increases catalase expression within cardiac mitochondria

Area of Science:

• Biochemistry
• Metabolic research
• Cardiovascular science

Background:

• Obesity is linked to diabetes and cardiovascular disease, often involving dyslipidemia and high triglycerides.
• Oxidative stress from lipid utilization is implicated in these diseases.
• The antioxidant enzyme network's response to high fat utilization is not well understood.

Purpose of the Study:

• To investigate the response of antioxidant enzymes in heart tissue to diet-induced obesity.
• To determine the role and localization of catalase during high fat utilization.
• To examine if catalase upregulation is a conserved response to conditions increasing lipid oxidation.

Main Methods:

• Utilized a multiplexed quantitative proteomics method to measure antioxidant enzyme expression in mouse heart tissue.
• Assessed catalase protein, activity, and mRNA levels.
• Compared antioxidant expression in diet-induced obese mice and fasted mice.

Main Results:

• Diet-induced obesity rapidly and specifically upregulated catalase protein, activity, and mRNA in heart tissue.
• Catalase was found in cardiac mitochondria, with increased content and activity during high fat feeding.
• A similar specific catalase increase was observed in mice fasted for 24 hours.

Conclusions:

• Increased catalase in cardiac mitochondria helps consume excess hydrogen peroxide (H2O2) produced by increased fat metabolism.
• Catalase expression is regulated to prevent damage while sensing diet composition via H2O2.
• This process may adjust insulin sensitivity to prioritize lipid metabolism for complete utilization.