title: E2F1 Transcription Factor Regulates O-linked N-acetylglucosamine (O-GlcNAc) Transferase and O-GlcNAcase Expression.
abstract: Protein O-GlcNAcylation, which is controlled by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), has emerged as an important posttranslational modification that may factor in multiple diseases. Until recently, it was assumed that OGT/OGA protein expression was relatively constant. Several groups, including ours, have shown that OGT and/or OGA expression changes in several pathologic contexts, yet the cis and trans elements that regulate the expression of these enzymes remain essentially unexplored. Here, we used a reporter-based assay to analyze minimal promoters and leveraged in silico modeling to nominate several candidate transcription factor binding sites in both Ogt (i.e. the gene for OGT protein) and Mgea5 (i.e. the gene for OGA protein). We noted multiple E2F binding site consensus sequences in both promoters. We performed chromatin immunoprecipitation in both human and mouse cells and found that E2F1 bound to candidate E2F binding sites in both promoters. In HEK293 cells, we overexpressed E2F1, which significantly reduced OGT and MGEA5 expression. Conversely, E2F1-deficient mouse fibroblasts had increased Ogt and Mgea5 expression. Of the known binding partners for E2F1, we queried whether retinoblastoma 1 (Rb1) might be involved. Rb1-deficient mouse embryonic fibroblasts showed increased levels of Ogt and Mgea5 expression, yet overexpression of E2F1 in the Rb1-deficient cells did not alter Ogt and Mgea5 expression, suggesting that Rb1 is required for E2F1-mediated suppression. In conclusion, this work identifies and validates some of the promoter elements for mouse Ogt and Mgea5 genes. Specifically, E2F1 negatively regulates both Ogt and Mgea5 expression in an Rb1 protein-dependent manner.
authors.affiliation: From the Institute of Molecular Cardiology and the Diabetes and Obesity Center, University of Louisville, Louisville, Kentucky 40202.
authors.forename: Senthilkumar
authors.initials: S
authors.lastname: Muthusamy
authors.affiliation: From the Institute of Molecular Cardiology and the Diabetes and Obesity Center, University of Louisville, Louisville, Kentucky 40202.
authors.forename: Kyung U
authors.initials: KU
authors.lastname: Hong
authors.affiliation: From the Institute of Molecular Cardiology and the Diabetes and Obesity Center, University of Louisville, Louisville, Kentucky 40202.
authors.forename: Sujith
authors.initials: S
authors.lastname: Dassanayaka
authors.affiliation: From the Institute of Molecular Cardiology and the Diabetes and Obesity Center, University of Louisville, Louisville, Kentucky 40202.
authors.forename: Tariq
authors.initials: T
authors.lastname: Hamid
authors.affiliation: From the Institute of Molecular Cardiology and the Diabetes and Obesity Center, University of Louisville, Louisville, Kentucky 40202 Steven.P.Jones@Louisville.edu.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Jones
mesh_terms: D041721:3T3-L1 Cells; D000818:Animals; D000951:Antigens, Neoplasm / Q000096:biosynthesis* / Q000235:genetics; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D057809:HEK293 Cells; D051548:Histone Acetyltransferases / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D006821:Hyaluronoglucosaminidase / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008817:Mice, Mutant Strains; D017351:N-Acetylglucosaminyltransferases / Q000096:biosynthesis* / Q000235:genetics; D020218:Response Elements / Q000502:physiology*; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C493754:E2f1 protein, mouse; D016160:Retinoblastoma Protein; D051548:Histone Acetyltransferases; D017351:N-Acetylglucosaminyltransferases; C063057:UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase; C115866:OGA protein, human; D006821:Hyaluronoglucosaminidase
keywords: E2F transcription factor; O-GlcNAcase; O-GlcNAcylation; O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT); gene transcription; retinoblastoma protein (pRb, RB)