Class II box consensus sequences in the HLA-DR alpha gene: transcriptional function and interaction with nuclear proteins.
The promoter regions of class II major histocompatibility complex genes contain two highly conserved sequences, the X and Y boxes, which may be involved in the control of class II gene expression. In this study, we correlate in vivo functional assays for cis-acting regulatory elements in the HLA-DR alpha gene with in vitro binding assays for trans-acting regulatory proteins. Mutagenesis and transient transfection analyses indicated that both the X and Y boxes were important for HLA-DR alpha promoter function in a B lymphoblastoid cell line. Although specific nuclear protein interactions with the X consensus sequence were not apparent, the Y box, which contained an inverted CCAAT sequence, did bind specifically to at least one nuclear protein. This Y box-binding protein was present in nuclear extracts of all cell types examined, including human B and T cells and HeLa cells. The molecular mass of the protein, as determined by photoactivated protein-DNA cross-linking, was approximately 40 to 50 kilodaltons. Mutagenesis of the Y box that decreased protein binding also decreased promoter activity, implying that protein binding to this DNA sequence is important for DR alpha promoter function.
Sherman
P A
PA
Lineberger Cancer Research Center, University of North Carolina, Chapel Hill 27599.
Basta
P V
PV
Moore
T L
TL
Brown
A M
AM
Ting
J P
JP
D001483:Base Sequence; D015342:DNA Probes / Q000032:analysis; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics*; D004720:Endonucleases; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II; D006684:HLA-DR Antigens / Q000235:genetics*; D006801:Humans; D008745:Methylation; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D013539:Simian virus 40 / Q000235:genetics; D015719:Single-Strand Specific DNA and RNA Endonucleases; D014162:Transfection; D014407:Tumor Cells, Cultured
D015342:DNA Probes; D004268:DNA-Binding Proteins; D006684:HLA-DR Antigens; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases