IDH3γ functions as a redox switch regulating mitochondrial energy metabolism and contractility in the heart

Area of Science:

• Cardiology
• Mitochondrial Metabolism
• Redox Signaling

Background:

• Cardiac function is closely regulated by redox signaling pathways.
• The specific protein targets of hydrogen peroxide (H2O2) in cardiomyocytes that impair cardiac contractility during oxidative stress remain largely unidentified.

Purpose of the Study:

• To identify redox-sensitive proteins affected by H2O2 in cardiomyocytes.
• To elucidate the mechanism linking H2O2-induced oxidative stress to impaired cardiac function.

Main Methods:

• Utilized a chemogenetic mouse model (HyPer-DAO mice) for controlled H2O2 production in cardiomyocytes.
• Employed a redox-proteomics approach to identify protein targets of H2O2.
• Performed microsecond molecular dynamics simulations and cysteine-gene-edited cell experiments.

Main Results:

• Increased endogenous H2O2 production in cardiomyocytes led to reversible impairment of cardiac contractility in vivo.
• Identified the gamma-subunit of isocitrate dehydrogenase 3 (IDH3γ) as a critical redox switch.
• Demonstrated that specific cysteine residues (Cys148 and Cys284) in IDH3γ are key to H2O2-dependent regulation of IDH3 activity.

Conclusions:

• H2O2 directly modulates mitochondrial metabolism in cardiomyocytes by targeting IDH3γ.
• IDH3γ acts as a redox switch, linking oxidative stress to altered metabolic activity and cardiac function.
• This study reveals a novel mechanism for redox-mediated regulation of mitochondrial function in the heart.