O‐GlcNAc signaling attenuates mitochondrial permeability transition

Abstract

We have shown that glycosylation of proteins with O‐linked β‐N‐acetylglucosamine (O‐GlcNAc) preserves mitochondrial membrane potential, attenuates post‐hypoxic injury, and reduces myocardial infarct size in vivo. Based on our recent identification of voltage dependent anion channel (VDAC) as an O‐GlcNAc modified protein, we hypothesized that O‐GlcNAc signaling mediates cardioprotection by attenuating sensitivity to mPTP formation. Here, isolated cardiac mitochondria from Vehicle‐ (normal O‐GlcNAc), PUGNAc‐ (high O‐GlcNAc; 50mg/kg, 18hours), or TT04‐treated (low O‐GlcNAc; 10mg/kg, 18hours) C57BL/6J mice showed no difference in total VDAC levels (n>/=3/group). for O‐GlcNAc and immunoblot for VDAC (n>/=3/group), and vice versa, revealed a significant increase in O‐ GlcNAc modified VDAC for cardiac mitochondria from high O‐GlcNAc mice with Vehicle, while a significant reduction of O‐GlcNAc‐modified VDAC was observed with cardiac mitochondria from low O‐GlcNAc mice compared to Vehicle. To assess functional effects of changes in O‐GlcNAc modification of VDAC on mPTP formation, cardiac mitochondria from high, normal, and low O‐GlcNAc mice were challenged with 100μM CaCl2 and the decrease in spectrohotometric absorbance recorded as an index of mitochondrial swelling. Mitochondria from high O‐GlcNAc mice were significantly less sensitive to calcium‐induced swelling, those from low O‐GlcNAc mice were more sensitive to calcium‐induced swelling compared with Vehicle. We that prevention of mPTP formation, potentially via O‐GlcNAc modification of VDAC, represents a novel mechanism of cardioprotection. NIH (HL0833220), AHA (0535270N) and AHA (0715493B).