The octamer motif is a B-lymphocyte-specific regulatory element of the HLA-DR alpha gene promoter.
The human class II gene, HLA-DR alpha, contains an octanucleotide sequence ATTTGCAT located approximately 40 base pairs upstream of the transcription initiation site. We have investigated the transcriptional function of the DR alpha octamer in human B-lymphoblastoid cells and non-B cells. Deletion and substitution mutagenesis of the octamer sequence greatly reduced the activity of the DR alpha promoter in both in vivo and in vitro cell-free transcription systems of B-cell origin. Conversely, these mutations did not affect promoter activity in several non-B-cell lines that express the DR alpha gene. Removal of octamer-binding proteins by in vivo titration with an octamer-containing competitor plasmid reduced DR alpha promoter activity in B-lymphoblastoid cells. These results suggest that a protein-octamer interaction, most likely involving the B-cell-specific octamer binding protein (OTF-2), is required for DR alpha promoter function in B-lymphoblastoid cells but not in non-B cells.
Sherman
P A
PA
Lineberger Cancer Research Center, University of North Carolina, Chapel Hill 27599.
Basta
P V
PV
Heguy
A
A
Wloch
M K
MK
Roeder
R G
RG
Ting
J P
JP
D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D002460:Cell Line; D002872:Chromosome Deletion; D004273:DNA, Neoplasm / Q000235:genetics; D005802:Genes, MHC Class II; D005809:Genes, Regulator; D006684:HLA-DR Antigens / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic
D004273:DNA, Neoplasm; D006684:HLA-DR Antigens