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Loss of O‐GlcNAc transferase activity sensitizes cardiac myocytes to post‐hypoxic death
Author(s) -
Ngoh Gladys Afor,
Watson Lewis J.,
Jones Steven P.
Publication year - 2008
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.22.1_supplement.750.10
Subject(s) - myocyte , gene silencing , gene knockdown , transfection , microbiology and biotechnology , chemistry , medicine , biology , endocrinology , gene , biochemistry
We recently reported that diabetic hearts have a paradoxical reduction in β‐ O ‐linked‐N‐acetylglucosamine ( O ‐GlcNAc) signaling. Because enhancement of O ‐GlcNAc signaling is cardioprotective, we hypothesized that loss of OGT activity is sufficient to sensitize nondiabetic cardiac myocytes to post‐hypoxic injury. Here, loxP‐ flanked OGT neonatal mouse cardiac myocytes (n=3/group) were infected with an adenovirus carrying cre recombinase gene (AdCre, 72hours; 50 moi). Expression of cre recombinase reduced OGT expression (44+/−16%, p<0.05) and O ‐GlcNAc levels (28+/−5%, p< 0.05) according to western blotting. Furthermore, such transcriptional silencing of OGT significantly (122+/−7%, p< 0.05) exacerbated post‐hypoxic injury according to LDH release. To further confirm these findings, neonatal rat cardiac myocytes were transfected with 30nM OGT siRNA, to knockdown OGT. OGT siRNA‐treatment significantly reduced OGT (49+/−8%, p<0.05) and O ‐GlcNAc levels (75+/−13%, p<0.05) compared with control siRNA. Such decrement in O ‐GlcNAc signaling corresponded with exacerbated post‐hypoxic LDH release (120+/−2%, p<0.05). We conclude that reduced OGT activity diminishes O ‐GlcNAc levels and sensitizes cardiac myocytes to lethal cell injury. Such insights support the hypothesis that defects in O ‐GlcNAc signaling are at least partially responsible for the sensitivity of the diabetic myocardium to ischemia‐reperfusion injury. Moreover, basal OGT expression is elemental for the ability of cardiac myocytes to withstand hypoxic injury. NIH (HL0833220), AHA (0535270N) and AHA (0715493B).