Biochemical and Biophysical Research Communications, Vol.467, No.2, 341-347, 2015
O-GlcNAc modification of Sp3 and Sp4 transcription factors negatively regulates their transcriptional activities
The addition of Olinked N-acetylglucosamine (OGlcNAc) on serine or threonine modifies a myriad of proteins and regulates their function, stability and localization. OGlcNAc modification is common among chromosome-associated proteins, such as transcription factors, suggesting its extensive involvement in gene expression regulation. In this study, we demonstrate the OGlcNAc status of the Sp family members of transcription factors and the functional impact on their transcriptional activities. We highlight the presence of OGlcNAc residues in Sp3 and Sp4, but not Sp2, as demonstrated by their enrichment in GlcNAc positive protein fractions and by detection of OGlcNAc residues on Sp3 and Sp4 co-expressed in Escherichia coli together with OGlcNAc transferase (OGT) using an OGlcNAc-specific antibody. Deletion mutants of Sp3 and Sp4 indicate that the majority of OGlcNAc sites reside in their N-terminal transactivation domain. Overall, using reporter gene assays and co-immunoprecipitations, we demonstrate a functional inhibitory role of OGlcNAc modifications in Sp3 and Sp4 transcription factors. Thereby, our study strengthens the current notion that OGlcNAc modification is an important regulator of protein interactome. (C) 2015 Elsevier Inc. All rights reserved.