Transactivation of the Moloney murine leukemia virus and T-cell receptor beta-chain enhancers by cbf and ets requires intact binding sites for both proteins.
The Moloney murine leukemia virus (Mo-MLV) enhancer contains binding sites (LVb and LVc) for the ets gene family of proteins and a core site that binds the polyomavirus enhancer-binding protein 2/core-binding factor (cbf) family of proteins. The LVb and core sites in the Mo-MLV enhancer contribute to its constitutive activity in T cells. All three binding sites (LVb, LVc, and core) are required for phorbol ester inducibility of the Mo-MLV enhancer. Adjacent binding sites for the ets and cbf proteins likewise constitute a phorbol ester response element within the human T-cell receptor beta-chain (TCR beta) enhancer and contribute to constitutive transcriptional activity of the TCR beta enhancer in T cells. Here we show that the CBF alpha subunit encoded by the mouse Cbfa2 gene (the murine homolog of human AML1) and three ets proteins, Ets-1, Ets-2, and GA-binding protein (GABP), transactivate both the Mo-MLV and mouse TCR beta enhancer in transient-expression assays. Moreover, we show that transactivation by Cbf alpha 2 requires both intact ets and cbf binding sites. Transactivation by Ets-1, Ets-2, and GABP likewise requires intact binding sites for ets proteins and CBF. Supportive biochemical analyses demonstrate that both proteins can bind simultaneously to a composite enhancer element. These findings suggest that ets and cbf proteins cooperate in vivo to regulate transcription from the Mo-MLV and TCR beta enhancers.
Sun
W
W
Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
Graves
B J
BJ
Speck
N A
NA
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D050657:Core Binding Factor alpha Subunits; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D008979:Moloney murine leukemia virus / Q000235:genetics*; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D050657:Core Binding Factor alpha Subunits; D017931:DNA Primers; D004268:DNA-Binding Proteins; C494041:ETS1 protein, human; C494042:Ets1 protein, mouse; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D016693:Receptors, Antigen, T-Cell, alpha-beta; D050656:Transcription Factor AP-2; D014157:Transcription Factors