Transcriptional regulation of the MHC class II trans-activator (CIITA) promoter III: identification of a novel regulatory region in the 5'-untranslated region and an important role for cAMP-responsive element binding protein 1 and activating transcription factor-1 in CIITA-promoter III transcriptional activation in B lymphocytes.
The class II trans-activator (CIITA), which acts as a master regulator for expression of MHC class II genes, is expressed constitutively in mature B cells. This constitutive expression of CIITA is driven by CIITA promoter III (CIITA-PIII). However, little is known about the factors that control the B cell-mediated trans-activation of CIITA-PIII. In this study using B cells we have identified several cAMP-responsive elements (CREs) in the proximal promoter and in the 5'-untranslated region (5'-UTR) that are involved in the activation of CIITA-PIII. We show that activating transcription factor (ATF)/CRE binding protein (CREB) factors bind to the CREs in vitro and in vivo. Notably, our results also reveal that the 5'-UTR of CIITA-PIII functions as an important regulatory region in B lymphocytes. Furthermore, transient cotransfections of a CIITA-PIII luciferase reporter construct with either CREB-1 or ATF-1 boost CIITA-PIII trans-activation in a dose-dependent manner, which was further enhanced by addition of general coactivator CREB-binding protein. Transient transfections using mutant CIITA-PIII luciferase reporter constructs that either lack the (5'-UTR) or abolish binding of CREB-1 and ATF-1 to the CRE located in activation response element-2, displayed severely reduced promoter activity in B cells. A similar successive deletion of the CREs resulted in a subsequent reduction of CREB-1-induced activity of CIITA-PIII in B cells. Together our results argue for an important role of ATF/CREB factors and the 5'-UTR of CIITA-PIII in the trans-activation of CIITA-PIII in B cells.
van der Stoep
Nienke
N
Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, The Netherlands.
Quinten
Edwin
E
van den Elsen
Peter J
PJ
D020121:5' Untranslated Regions / Q000235:genetics / Q000276:immunology*; D051697:Activating Transcription Factor 1; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism*; D002461:Cell Line, Transformed; D000242:Cyclic AMP / Q000235:genetics / Q000494:pharmacology / Q000502:physiology; D051786:Cyclic AMP Response Element Modulator; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D005802:Genes, MHC Class II; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000276:immunology*; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology; D020218:Response Elements / Q000235:genetics / Q000276:immunology; D017384:Sequence Deletion; D015534:Trans-Activators / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics / Q000276:immunology*; D014407:Tumor Cells, Cultured
D020121:5' Untranslated Regions; D051697:Activating Transcription Factor 1; C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; C083728:MHC class II transactivator protein; D009687:Nuclear Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051786:Cyclic AMP Response Element Modulator; D000242:Cyclic AMP