Multiple transcription factors regulate the inducible expression of the human complement receptor 2 promoter.
Complement receptor 2 (CR2) is regulated at the transcriptional level, but the promoter elements and the transcription factors that bind to them and contribute to its regulation are unknown. After documenting that PMA and cAMP induced the activity of the CR2 promoter by 10-fold, we conducted promoter truncation and mutagenesis experiments, in conjunction with shift assays, to determine the functionally important regions of the promoter and the proteins that bind to them. We identified two regions, separated by approximately 900 nucleotides, which together were responsible for inducible promoter activity. Mutagenesis of single promoter elements demonstrated a functional upstream stimulatory factor/E box in the TATA box-proximal region and three equally important, closely spaced, CREB/AP-1 half-sites in the upstream promoter region. The cAMP response element-binding protein (CREB)/AP-1 half-sites bound in vitro Jun and CREB that are induced by protein kinases A and/or C. The 900-nucleotide segment stretching between the above two regions had no functional impact on the induced transcription, and its deletion increased the promoter activity. Finally, a region upstream of the distal site had a repressor activity on CR2 transcription. Moreover, IL-4 induced binding of CREB and AP-1 to the upstream promoter elements and resulted in increased CR2 surface protein expression. These studies have characterized regions of the CR2 promoter and the transcription factors that bind to them and are crucial to induced CR2 expression. Our studies may provide insights to novel approaches to modulate B cell function by regulating CR2 gene transcription.
Vereshchagina
L A
LA
Department of Cellular Injury, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA.
Tolnay
M
M
Tsokos
G C
GC
D020121:5' Untranslated Regions / Q000187:drug effects / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001483:Base Sequence; D001666:Binding Sites, Antibody / Q000235:genetics; D003994:Bucladesine / Q000494:pharmacology; D019013:CD40 Antigens / Q000276:immunology; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D017930:Genes, Reporter / Q000187:drug effects / Q000276:immunology; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000276:immunology*; D017464:Receptors, Complement 3d / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D012045:Regulatory Sequences, Nucleic Acid / Q000276:immunology; D017384:Sequence Deletion / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
D020121:5' Untranslated Regions; D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D017464:Receptors, Complement 3d; D014157:Transcription Factors; D015847:Interleukin-4; D003994:Bucladesine; D013755:Tetradecanoylphorbol Acetate