Activation of the U2 snRNA promoter by the octamer motif defines a new class of RNA polymerase II enhancer elements.
The recent discovery that the activation domains of transcriptional activators (e.g., GAL4) from a number of species are interchangeable has led to the concept of a general mechanism for activation of RNA polymerase II genes. We have examined the different activities of the SV40 octamer motif ATGCAAAG in B cells and in HeLa cells in the context of either the beta-globin promoter, a TATA-box-containing mRNA promoter, or the U2 snRNA promoter, which contains a snRNA-specific proximal element. In the context of the beta-globin promoter, the octamer motif is a B-cell-specific enhancer element, whereas it is a ubiquitous enhancer element for the U2 snRNA promoter. The U2 promoter is unique in that it is not activated by enhancer elements that activate the beta-globin promoter, and a hybrid U2 promoter containing the upstream activating sequence UASG is not stimulated by a yeast GAL4 trans-activator. Together, these observations suggest that in the context of the U2 promoter, the octamer motif defines a new class of RNA polymerase II enhancer elements, which bind transcription factors that trans-activate gene expression by a different mechanism than the general mechanism mentioned above. These results are discussed in light of the possibility that the ubiquitous octamer binding protein Oct-1 and the B-cell-specific octamer binding protein Oct-2 are involved in the activation of the U2 and beta-globin promoters, respectively.
Tanaka
M
M
Cold Spring Harbor Laboratory, New York 11724.
Grossniklaus
U
U
Herr
W
W
Hernandez
N
N
D001402:B-Lymphocytes; D004268:DNA-Binding Proteins; D004742:Enhancer Elements, Genetic; D005656:Fungal Proteins / Q000235:genetics; D005914:Globins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008957:Models, Genetic; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D013539:Simian virus 40 / Q000235:genetics; D018139:Simplexvirus / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014162:Transfection; D014764:Viral Proteins / Q000235:genetics
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D012342:RNA, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D005914:Globins; D012319:RNA Polymerase II