ABSTRACT
O-GlcNAc transferase (OGT)-catalyzed protein O-GlcNAcylation is implicated in diverse cellular events. In the present study, we report the regulation of ogt transcription by the hepatocyte nuclear factor 1 homologue A (HNF1A) in HEK293T cells. We first identified a core ogt promoter (-150 to +200 bp) and confirmed its binding to the transcription factor HNF1A. We found that HNF1A regulates ogt transcription in a time-dependent manner and that O-GlcNAcylation of HNF1A represses ogt transcription. Electron-transfer dissociation based tandem mass spectrometry analysis revealed 14 O-GlcNAc sites on HNF1A, six of which are predominantly modified, including Ser303/304 , Ser471 , Ser560 and Thr563/564 . We further found that loss of O-GlcNAcylation at Ser303/304 or Thr563/564 significantly elevates ogt transcription. These findings highlight a negative feedback mechanism for ogt transcription, which partially explains the homeostasis of cellular O-GlcNAcylation.
