Abstract 16374: Perm1 Regulates Mitochondrial Energetics Through O-Glcnacylation in Cardiomyocytes

Abstract

O-GlcNAcylation is a post-translational modification of proteins that plays an important role in cellular homeostasis and stress responses. Two enzymes regulate O-GlcNAcylation: O-GlcNAc transferase (OGT) that adds O-GlcNAc to proteins; O-GlcNAcase (OGA) that removes O-GlcNAc from proteins. While O-GlcNAcylation is necessary to respond to ischemia/reperfusion injury, chronic activation of O-GlcNAcylation in the heart has adverse effects, and excessive O-GlcNAcylation leads to the development of heart failure. However, there is currently no therapy for heart failure that targets O-GlcNAcylation. Perm1 is a striated muscle-specific regulator of mitochondrial bioenergetics. We previously demonstrated that Perm1-knockout mice exhibit reduced cardiac function and myocardial energy reserve, in association with excessive O-GlcNAcylation and upregulation of OGT. Here, we hypothesized that Perm1 maintains mitochondrial energetics by suppressing O-GlcNAcylation. We found that adenovirus-mediated overexpression of Perm1 in cardiomyocytes significantly decreased O-GlcNAcylation (Figure 1A-B) and increased the basal and maximal respiration and ATP production rates as compared with control in Cell Mito Stress Test using a Seahorse 96x flux analyzer (orange vs. green, Figure 1C-D). Furthermore, the increased levels of O-GlcNAcylated proteins (215% of control, p<0.05) via silencing OGA (si-OGA) in cardiomyocytes significantly decreased the basal and maximal respiration capacity and ATP production rates as compared with control (green vs. purple, Figure 1C-D), all which were completely rescued by Perm1 overexpression (blue, Figure 1C-D). These results suggest that Perm1 positively regulates mitochondrial energetics, in part, via suppressing O-GlcNAcylation and that Perm1 might be a new therapeutic target of heart failure that maintains mitochondrial function through preventing excessive O-GlcNAcylation under pathological stress.