Nuclear factor I can functionally replace transcription factor Sp1 in a U2 small nuclear RNA gene enhancer.
Polymerase II transcription of a human gene for the small nuclear RNA U2 is dependent on two different promoter elements: a TATA-equivalent proximal sequence element and a distal enhancer element, which has been shown to contain Sp1- and octamer-binding sites. We have investigated the functional interplay between these transcription factor-binding sites of the enhancer, following transfection of U2 maxigene constructions into HeLa cells. There is a functional non-additive co-operation between the octamer-binding factor and Sp1, which is not dependent on the evolutionally conserved steric arrangement of these binding sites. We demonstrate that the conserved Sp1-binding site of the U2 enhancer can be fully substituted by a nuclear factor I (NFI) binding site, and that the octamer-binding factor functions in stimulating transcription in conjunction with either Sp1 or NFI. Since the octamer-binding factor is most probably the same protein as nuclear factor III (NFIII), the results imply that the NFI/NFIII complex, involved in adenovirus DNA replication, also can function as an efficient activator of transcription.
Janson
L
L
Department of Medical Genetics, Uppsala University, Biomedical Center, Sweden.
Weller
P
P
Pettersson
U
U
D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D006367:HeLa Cells; D051863:Host Cell Factor C1; D006801:Humans; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors; D009687:Nuclear Proteins / Q000235:genetics; D050811:Octamer Transcription Factor-1; D012342:RNA, Small Nuclear; D014157:Transcription Factors / Q000235:genetics*; D051840:Y-Box-Binding Protein 1
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; D012342:RNA, Small Nuclear; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human