The transcription factors Sp1 and Oct-1 interact physically to regulate human U2 snRNA gene expression.
The expression of human small nuclear U2 RNA genes is controlled by the proximal sequence element (PSE), which determines the start site of transcription, and a distal sequence element (DSE). The DSE contains an octamer element and three Sp1 binding sites. The octamer, like the PSE, is essential for U2 transcription. The Sp1 sites contribute to full promoter activity by distance-dependent cooperative interactions with the transcription factors Sp1 and Oct-1. Here we show that purified recombinant Sp1 and Oct-1 bind cooperatively to the DSE and that they physically interact in vitro. Furthermore, we show that Sp1 and Oct-1 interact in vivo using a yeast two-hybrid system. The domain of Sp1 which interacts with Oct-1 is confined to the region necessary for transcriptional stimulation of U2 RNA transcription. This region contains the glutamine-rich activation domain B and a serine/threonine-rich part. The results demonstrate that Sp1, in addition to binding to a number of other factors, also interacts directly with transcription factor Oct-1.
Ström
A C
AC
Department of Medical Genetics, Uppsala University, Biomedical Centre, Uppsala, Sweden.
Forsberg
M
M
Lillhager
P
P
Westin
G
G
D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000494:pharmacology*; D004347:Drug Interactions; D005786:Gene Expression Regulation / Q000187:drug effects*; D051863:Host Cell Factor C1; D006801:Humans; D050811:Octamer Transcription Factor-1; D012342:RNA, Small Nuclear / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism / Q000494:pharmacology*; D014157:Transcription Factors / Q000378:metabolism / Q000494:pharmacology*
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; D012342:RNA, Small Nuclear; D011993:Recombinant Fusion Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D004247:DNA