O‐GlcNAc signaling attenuates mitochondrial permeability transition

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 CaCl 2 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).