The beta-globin dominant control region: hypersensitive site 2.
The Dominant Control Region (DCR) of the human beta-globin gene locus consists of four strong hypersensitive sites (HSS) upstream of the epsilon-globin gene. Addition of these sites confers copy number dependent expression on the human beta-globin gene in murine erythroleukaemia cells and transgenic mice, at levels comparable with the endogenous mouse globin genes. We have shown previously that a 1.9 kb fragment comprising HSS 2 accounts for 40-50% of the full effect of the DCR. In this paper we describe a deletional analysis of HSS 2. We show that a 225 bp fragment is sufficient to direct high levels of expression of the human beta-globin gene which is copy number dependent and integration site independent. This 225 bp fragment overlaps the major region that is hypersensitive 'in vivo'. DNase I footprinting shows the presence of four binding sites for the erythroid specific protein NF-E1; the three other footprinted regions display a remarkable redundancy of the sequence GGTGG and bind a number of proteins including Sp1 and the CACC box protein. The significance of these results for the regulation of globin gene expression is discussed.
Philipsen
S
S
Laboratory of Gene Structure and Expression, National Institute for Medical Research, Mill Hill, London, UK.
Talbot
D
D
Fraser
P
P
Grosveld
F
F
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D003850:Deoxyribonuclease I; D005796:Genes; D005799:Genes, Dominant; D005914:Globins / Q000235:genetics*; D006801:Humans; D007942:Leukemia, Experimental; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010957:Plasmids; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity; D014162:Transfection
D015345:Oligonucleotide Probes; D005914:Globins; D004247:DNA; D003850:Deoxyribonuclease I