The mouse ME1 gene (HEB, REB and GE1, homo-logues in human, rat and chick, respectively) Is a member of the nontissue-specific hellx-loop-helix (HLH) gene family that Includes E2A, E2-2 and Droso-phlla daughteriess. We have examined the factors that control ME1 gene expression. ME1 Is a single copy gene that spans ≥150 kb of DNA and contains >10 exons. Transcription was directed by an unusual Initiator element that contained a 13 bp poly d(A) tract flanked by palindromlc and inverted repeat sequences. Both RNase protection and primer extension analyses mapped the ME1 transcriptional start site to the center of the 13 bp poly d(A) tract. The ME1 Initiator and Its proximal sequences were required for promoter activity, supported basal levels of transcription, and contributed to cell type-specific gene expression. Other c/s-elements utilized by the TATA-less ME1 promoter Included a cluster of Sp1 response elements, E-boxes and a strong repressor. Collectively, our results suggest that the ME1 initiator and other c/s-elements In the proximal promoter play an important role In regulating ME1 gene expression.
All Science Journal Classification (ASJC) codes