title: Repression mechanisms of the I-A beta gene of the major histocompatibility complex.
abstract: The mechanisms of regulation of I-A beta gene expression in the murine major histocompatibility complex by transcriptional repression are reviewed. Active and passive repression mechanisms are presented. The transcription factor PU.1 actively inhibits the expression of I-A beta through the binding to a DNA sequence near the Y box, a cis-element in the promoter necessary for transcription. This interaction probably interferes with the preinitiation complex assembly. NF-Y is a transcription factor that binds to the Y box and has two constituents: NF-YA (that binds weakly to DNA) and NF-YB (that increases the binding of NF-YA to DNA). The dbpA protein represses the expression of I-A beta by a quenching mechanism, forming a complex with NF-YA and the dbpB protein by sequestering the NF-YB protein. A similar mechanism is observed with the glucocorticoid receptor that binds to the X-box binding proteins and inhibits their interaction with the X box. These results are examples of cross-talk between proteins, which may help us to understand the regulation of I-A beta gene expression.
authors.affiliation: Department of Physiology (Immunology), Faculty of Biology, University of Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Lloberas
authors.forename: C
authors.initials: C
authors.lastname: Soler
authors.forename: A
authors.initials: A
authors.lastname: Celada
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins; D053487:DEAD-box RNA Helicases; D004268:DNA-Binding Proteins / Q000378:metabolism; D029968:Escherichia coli Proteins; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II; D006801:Humans; D051379:Mice; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020365:RNA Helicases; D016601:RNA-Binding Proteins; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D001426:Bacterial Proteins; D022762:CCAAT-Enhancer-Binding Proteins; D053487:DEAD-box RNA Helicases; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D020365:RNA Helicases; D016601:RNA-Binding Proteins; D011965:Receptors, Glucocorticoid; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; D000099232:Proto-Oncogene Protein Spi-1; C070856:YBX1 protein, human; C065908:dbpA protein, E coli