Regulation of the murine Ddelta2 promoter by upstream stimulatory factor 1, Runx1, and c-Myb.
Accessibility control of V(D)J recombination at Ag receptor loci depends on the coordinate activities of transcriptional enhancers and germline promoters. Recombination of murine Tcrd gene segments is known to be regulated, at least in part, by the Tcrd enhancer (Edelta) situated in the Jdelta2-Cdelta intron. However, there has been little characterization of promoters and other cis-acting elements that are activated by or collaborate with Edelta and that might function to regulate Tcrd gene recombination events. We now describe a strong promoter that is tightly associated with the murine Ddelta2 gene segment. EMSAs reveal that upstream stimulatory factor 1, Runx1, c-Myb, lymphoid enhancer binding factor 1, NF1, and E47 all interact with this promoter in vitro. Of these, upstream stimulatory factor 1, Runx1, and c-Myb appear necessary for full promoter activity in transiently transfected cells. Moreover, the same three factors were found to interact with the promoter in vivo by chromatin immunoprecipitation. We suggest that these factors play important roles as Edelta-dependent regulators of Ddelta2 accessibility in vivo. Consistent with the established roles of c-Myb and Runx factors in Edelta function, we detected low level, enhancer-independent activity of the Ddelta2 promoter in transient transfection experiments. We speculate that the Ddelta2 promoter may play a role as a weak, enhancer-independent regulator in vivo, and might contribute to residual Tcrd rearrangement in Edelta(-/-) mice.
Carabana
Juan
J
Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
Ortigoza
Eric
E
Krangel
Michael S
MS
D000818:Animals; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins / Q000502:physiology; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D016694:Gene Rearrangement, delta-Chain T-Cell Antigen Receptor; D051379:Mice; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000502:physiology; D020598:Proto-Oncogene Proteins c-myb / Q000502:physiology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics; D011995:Recombination, Genetic; D014157:Transcription Factors / Q000502:physiology*; D051720:Upstream Stimulatory Factors
D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D016692:Receptors, Antigen, T-Cell, gamma-delta; C493726:Runx1 protein, mouse; D014157:Transcription Factors; D051720:Upstream Stimulatory Factors