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O‐GlcNAc Transferase is a Pro‐Survival Enzyme in Post‐Hypoxic Cardiac Myocytes
Author(s) -
Ngoh Gladys Afor,
Watson Lewis J.,
Jones Steven P.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a800
Subject(s) - myocyte , enzyme , hypoxia (environmental) , mitochondrion , transferase , chemistry , isozyme , inner mitochondrial membrane , membrane potential , biochemistry , lactate dehydrogenase , microbiology and biotechnology , pharmacology , biology , oxygen , organic chemistry
The post‐translational modification, O‐linked β‐N‐acetylglucosamine (O‐GlcNAc), is a metabolic and nutrient sensor which exerts cardioprotective effects. However, a paucity of information exists regarding the direct regulation of O‐GlcNAc levels in the heart. We evaluated the role of O‐GlcNAc transferase (OGT, which adds O‐GlcNAc to proteins) on cardiac myocyte survival following hypoxia‐reoxygentaion. We infected isolated cardiac myocytes (n=4–5/group) with adenovirus carrying the OGT gene (AdOGT), or treated with an OGT inhibitor (TT04), and subjected them to hypoxia and reoxygenation. Whole cell lysates were immunoblotted for O‐GlcNAc levels and myocyte damage following reoxygenation was spectrophotometrically assessed via LDH release. Timelapse fluorescence microscopy using tetramethylrhodamine methyl ester (TMRM) was used to assess the post‐hypoxic loss of mitochondrial membrane potential. AdOGT significantly augmented O‐GlcNAc levels (p<0.05 compared to control), produced a significant reduction in LDH release, and preserved mitochondrial membrane potential. OGT inhibition (TT04) significantly reduced (p<0.05) O‐GlcNAc levels, exacerbated LDH release, and hastened the loss of mitochondrial membrane potential. We conclude that OGT is a previously unrecognized, pro‐survival enzyme in cardiac myocytes that exerts its effects via augmentation of O‐GlcNAc levels. Funded by NIH (HL0833220) and AHA (0535270N).