Flanking and intragenic sequences regulating the expression of the rabbit alpha-globin gene.
Despite their descent from a common ancestral gene and the requirement for coordinated, tissue-specific regulation, the alpha- and beta-globin genes in many mammals are regulated in distinctly different ways. Unlike the beta-globin gene, the rabbit alpha-globin gene is transiently expressed at a high level without an added enhancer in transfected erythroid and non-erythroid cells. By examining a series of alpha/beta fusion genes, we show that internal sequences of the rabbit alpha-globin gene (within the first two exons and introns) are required along with the 5' flank for this enhancer-independent expression. Furthermore, deletion of the introns of the alpha-globin gene, or replacement by introns of the beta-globin gene, results in severely decreased expression of the transfecting genes. Hybrid constructs between segments of the alpha-globin gene and a luciferase gene confirm that internal alpha-globin sequences are needed for high level production of RNA in transfected cells. The flanking and internal sequences implicated in regulation of the rabbit alpha-globin gene coincide with a prominent CpG-rich island and may comprise an extended promoter (including both flanking and intragenic sequences) that is active in transfected cells without an enhancer.
James-Pederson
M
M
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802.
Yost
S
S
Shewchuk
B
B
Zeigler
T
T
Miller
R
R
Hardison
R
R
D000818:Animals; D001665:Binding Sites; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D050981:Erythroid-Specific DNA-Binding Factors; D005786:Gene Expression Regulation / Q000235:genetics*; D005796:Genes; D005914:Globins / Q000235:genetics*; D006801:Humans; D008156:Luciferases / Q000235:genetics; D011401:Promoter Regions, Genetic; D012313:RNA / Q000096:biosynthesis; D011817:Rabbits; D012045:Regulatory Sequences, Nucleic Acid; D017384:Sequence Deletion; D013539:Simian virus 40 / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D012313:RNA; D005914:Globins; D008156:Luciferases