Dynamic interactions of TATA‐box binding protein with promoters is regulated by GlcNAcylation (607.17)

Abstract

The GlcNAcylation is an intracellular posttranslational modification dynamically controlled by two enzymes. OGT catalyzes the transfer of a single O‐GLcNAc moiety from UDP‐GlcNAc to a Ser or Thr residue, whereas OGA removes it. Alterations of the GlcNAcylation profile appear in neurodegenerative disorders, diabetes and cancer. The GlcNAcylation rate of proteins is tightly correlated to the concentration of UDP‐GlcNAc, the end product of the hexosamine biosynthetic pathway, which varies according to environmental and nutritional factors. Interestingly, literature points out a regulation of the basal transcription machinery by O‐GlcNAc. TATA‐box binding protein (TBP) is a key player in regulating transcription since it is required for the activity of all three RNA polymerases. DNA‐bound TBP acts as a dock for recruitment of basal transcription factors and the RNA polymerase II to formation of a functional pre‐initiation complex (PIC). DNA‐bound TBP can also be recognized by NC2 and TAF172. NC2 stabilizes the chromatin interaction of TBP, whereas the association of TBP with TAF172 forms B‐TFIID and promotes its release.Here, we showed that DNA‐bound TBP is modified by O‐GlcNAc on its N‐terminal domain and this GlcNAcylation impairs the recruitment of TAF172 to the DNA‐bound TBP in vitro and the formation of B‐TFIID in vivo. Indeed, using STZ‐treated rat models, we showed that TBP/TAF172 association is decreased in diabetes. Owing the fact that B‐TFIID dynamically regulates the chromatin interaction of TBP, we investigated the dynamic behavior of TBP and TBP O‐GlcNAc by Strip‐FRAP and ChIP assays. Collectively, our results indicate that B‐TFIID formation and TBP dynamics on gene promoters is regulated by O‐GlcNAc.Grant Funding Source: Supported by NIH R01CA42486, R01DK61671, N01‐HV‐00240, P01HL107153