O‐GlcNAc Plays a Role in Nrf2 Regulation in the Myocardium

Abstract

The redox sensitive transcription factor NF‐E2–related factor 2 (Nrf2) protects against oxidative stress and its activity is aberrant in type 2 diabetes.. Acute increases in the protein posttranslational attachment of O‐linked β‐N‐acetylglucosamine (O‐GlcNAc) to serine/threonine residues have been shown to mitigate oxidative stress responses in the heart. This suggests that O‐GlcNAc may play a role in Nrf2 signaling; however, the role of O‐GlcNAc modification on Nrf2 remains to be elucidated. We examined Nrf2‐mediated genes in a tamoxifen‐inducible cardiomyocyte‐specific OGT knockdown (OGTKD) mouse. We also augmented O‐GlcNAc in cardiomyocytes (H9C2 cell line) and examined Nrf2 protein levels and mRNA of Nrf2‐mediated genes. Immunoprecipitation demonstrated that Nrf2 is O‐GlcNAc modified in the heart. Our in vivo model showed that Nrf2 protein was increased (p<0.05) while mRNA of the Nrf2 gene‐product catalase was reduced in the OGTKD mouse(p<0.05). Conversely, our in vitro experiments demonstrated that increasing protein O‐GlcNAcylation in H9C2 cells increased transcription of the Nrf2‐mediate genes catalase, glutamate‐cysteine ligase (GCLM), and heme oxygenase 1 (HMOX1) (p<.05). These data provide evidence for O‐GlcNAc as novel post‐translational modification of Nrf2 and suggest that O‐GlcNAcylation plays a role in regulating Nrf2 signaling.