Role of O‐GlcNAcylation in regulating mitophagy in cardiomyocytes (693.14)

Abstract

Acute increases in the post‐translational protein modification O‐linked‐N‐acetylglucosamine (O‐GlcNAc) have been shown to protect cardiomyocytes against oxidative stress and this has been associated with O‐GlcNAcylation of mitochondrial proteins. Mitophagy, a type of cargo‐mediated autophagy, protects against oxidative stress by removing damaged mitochondria. Therefore the goal of this study was to determine whether O‐GlcNAcylation plays a role in regulating mitophagy in AC16 immortalized human ventricular cardiomyocyte cells. Cells were treated with 2,3‐dimethoxy‐1,4‐napthoquinone (DMNQ, 20 µM), a redox cycling agent which increases mitochondrial reactive oxygen species (ROS) and FCCP (0.5 µg/mL), a mitochondrial uncoupler commonly used to induce mitophagy. Following 3 hour treatment with DMNQ or FCCP, O‐GlcNAc levels were decreased and this was associated with increased levels of total PINK1 and increased mitochondrial Parkin. Increasing basal O‐GlcNAc levels for 2 hours with thiamet‐G (3 µM) a highly selective inhibitor for O‐GlcNAcase, attenuated the loss of O‐GlcNAc induced by both DMNQ and FCCP treatment and appeared to increase basal PINK1 levels. These results support the concept that protein O‐GlcNAcylation plays a role in regulating mitophagy and that this could contribute to the protection against oxidative stress. Future studies will include quantifying the effects of DMNQ and thiamet‐G on mitochondrial function using XF24 Extracellular Flux Analyzer as well as determining whether PINK1 or Parkin are targets for O‐GlcNAcylation.Grant Funding Source: Supported by NIH grants HL101192 and HL110366