Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2833309 | Molecular Immunology | 2007 | 11 Pages |
Major histocompatibility class II (MHC-II) genes are coordinately regulated by conserved, upstream promoter elements that are bound cooperatively by cyclic AMP response element binding protein (CREB), regulatory factor X (RFX), and nuclear factor Y (NF-Y). These DNA-binding proteins serve as a scaffold for the transcriptional coactivator class II transactivator (CIITA). To determine how CREB interacts with RFX and CIITA, co-immunoprecipitations and reporter assays were performed using a variety of CREB mutants. These assays demonstrated that CREB interacted with CIITA and the RFX5 subunit of RFX through the C-terminal portion of CREB. This C-terminal portion of CREB was fully functional in MHC-II promoter reporter assays. Phosphorylation of CREB enhanced transcription from the reporter, but was not required for transcription. Phospho-CREB was found at the HLA-DRA promoter by chromatin immunoprecipitation, providing evidence for its role. Together, these data provide genetic and biochemical evidence of the specific associations between CREB and two elements of the MHC-II regulatory complex and of the role played by phosphorylated CREB at MHC-II promoters.