Glutaredoxin-2 Is Required to Control Oxidative Phosphorylation in Cardiac Muscle by Mediating Deglutathionylation Reactions

• Published in: The Journal of biological chemistry 2014-05, Vol.289 (21), p.14812-14828
• Main Authors: Mailloux, Ryan J., Xuan, Jian Ying, McBride, Skye, Maharsy, Wael, Thorn, Stephanie, Holterman, Chet E., Kennedy, Christopher R.J., Rippstein, Peter, deKemp, Robert, da Silva, Jean, Nemer, Mona, Lou, Marjorie, Harper, Mary-Ellen
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Animals; Bioenergetics; Cardiac Hypertrophy; Cardiac Metabolism; Electron Transport Complex I - metabolism; Fibrosis - genetics; Glutaredoxin-2; Glutaredoxins - genetics; Glutaredoxins - metabolism; Glutathione; Glutathione - metabolism; Glutathionylation; Hypertension - genetics; Hypertrophy, Left Ventricular - genetics; Hypertrophy, Left Ventricular - metabolism; Immunoblotting; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Electron; Mitochondria; Mitochondria, Heart - metabolism; Mitochondria, Heart - ultrastructure; Myocardium - metabolism; Myocardium - pathology; Organ Size - genetics; Oxidation-Reduction; Oxidative Phosphorylation; Redox
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.550574

Glutaredoxin-2 (Grx2) modulates the activity of several mitochondrial proteins in cardiac tissue by catalyzing deglutathionylation reactions. However, it remains uncertain whether Grx2 is required to control mitochondrial ATP output in heart. Here, we report that Grx2 plays a vital role modulating mitochondrial energetics and heart physiology by mediating the deglutathionylation of mitochondrial proteins. Deletion of Grx2 (Grx2−/−) decreased ATP production by complex I-linked substrates to half that in wild type (WT) mitochondria. Decreased respiration was associated with increased complex I glutathionylation diminishing its activity. Tissue glucose uptake was concomitantly increased. Mitochondrial ATP output and complex I activity could be recovered by restoring the redox environment to that favoring the deglutathionylated states of proteins. Grx2−/− hearts also developed left ventricular hypertrophy and fibrosis, and mice became hypertensive. Mitochondrial energetics from Grx2 heterozygotes (Grx2+/−) were also dysfunctional, and hearts were hypertrophic. Intriguingly, Grx2+/− mice were far less hypertensive than Grx2−/− mice. Thus, Grx2 plays a vital role in modulating mitochondrial metabolism in cardiac muscle, and Grx2 deficiency leads to pathology. As mitochondrial ATP production was restored by the addition of reductants, these findings may be relevant to novel redox-related therapies in cardiac disease. Mitochondrial proteins are controlled by glutaredoxin-2 (Grx2)-mediated deglutathionylation reactions. Grx2 deficiency compromises cardiac mitochondrial functions leading to hypertrophy and fibrosis in male mice. This is associated with deregulated glutathionylation reactions and mitochondrial dysfunction. Through deglutathionylation, Grx2 controls mitochondrial oxidative phosphorylation in cardiac muscle. Deregulated glutathionylation in heart can have pathological consequences.