The intra-mitochondrial O-GlcNAcylation system rapidly modulates OXPHOS function and ROS release in the heart.

Dontaine, Justine [UCL] Bouali, Asma Daussin, Frederic Bultot, Laurent [UCL] Vertommen, Didier [UCL] Martin, Manon [UCL] Rathagirishnan, Raahulan Cuillerier, Alexanne Horman, Sandrine [UCL] Beauloye, Christophe [UCL] Gatto, Laurent [UCL] Lauzier, Benjamin Bertrand, Luc [UCL] Burelle, Yan et al.[show all]

Protein O-GlcNAcylation is increasingly recognized as an important cellular regulatory mechanism, in multiple organs including the heart. However, the mechanisms leading to O-GlcNAcylation in mitochondria and the consequences on their function remain poorly understood. In this study, we use an in vitro reconstitution assay to characterize the intra-mitochondrial O-GlcNAc system without potential cytoplasmic confounding effects. We compare the O-GlcNAcylome of isolated cardiac mitochondria with that of mitochondria acutely exposed to NButGT, a specific inhibitor of glycoside hydrolase. Amongst the 409 O-GlcNAcylated mitochondrial proteins identified, 191 display increased O-GlcNAcylation in response to NButGT. This is associated with enhanced Complex I (CI) activity, increased maximal respiration in presence of pyruvate-malate, and a striking reduction of mitochondrial ROS release, which could be related to O-GlcNAcylation of specific subunits of ETC complexes (CI, CIII) and TCA cycle enzymes. In conclusion, our work underlines the existence of a dynamic mitochondrial O-GlcNAcylation system capable of rapidly modifying mitochondrial function.