Enhanced activation of the human histone H2B promoter by an Oct-1 variant generated by alternative splicing.
POU homeodomain proteins are important regulators of ubiquitous as well as tissue-specific transcription. These factors include the broadly expressed octamer motif-binding protein Oct-1 and the related cell-specifically expressed protein Oct-2. These two proteins differ in the types of octamer motif-containing promoters they preferentially activate; Oct-1 can activate RNA polymerase II transcription from a small nuclear RNA promoter better than Oct-2, which can better activate an mRNA-type promoter. We describe a variant Oct-1-encoding cDNA resulting from two separate alternate splices of the human oct-1 primary transcript; these alternate splices were present in all cell lines tested. This cDNA encodes an amino-terminally and carboxyl-terminally truncated form of Oct-1, called Oct-1B, which retains the DNA-binding POU domain and acquires a unique 12-amino acid carboxyl-terminal extension. In a transient expression assay, Oct-1B displayed an enhanced ability compared to the larger form of Oct-1 (called Oct-1A in this report) to activate the human histone H2B promoter, an mRNA-type promoter where a natural octamer motif is involved in cell cycle dependent transcription. Thus, the ability of Oct-1 related proteins to activate a natural regulatory target can be influenced by alternative splicing.
Das
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G
Cold Spring Harbor Laboratory, New York 11724.
Herr
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W
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000235:genetics*; D051863:Host Cell Factor C1; D006801:Humans; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D006657:Histones; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; D012333:RNA, Messenger; D014157:Transcription Factors; D004247:DNA