Multiple elements in human beta-globin locus control region 5' HS 2 are involved in enhancer activity and position-independent, transgene expression.
The human beta-globin Locus Control Region (LCR) has two important activities. First, the LCR opens a 200 kb chromosomal domain containing the human epsilon-, gamma- and beta-globin genes and, secondly, these sequences function as a powerful enhancer of epsilon-, gamma- and beta-globin gene expression. Erythroid-specific, DNase I hypersensitive sites (HS) mark sequences that are critical for LCR activity. Previous experiments demonstrated that a 1.9 kb fragment containing the 5' HS 2 site confers position-independent expression in transgenic mice and enhances human beta-globin gene expression 100-fold. Further analysis of this region demonstrates that multiple sequences are required for maximal enhancer activity; deletion of SP1, NF-E2, GATA-1 or USF binding sites significantly decrease beta-globin gene expression. In contrast, no single site is required for position-independent transgene expression; all mice with site-specific mutations in 5' HS 2 express human beta-globin mRNA regardless of the site of transgene integration. Apparently, multiple combinations of protein binding sites in 5' HS 2 are sufficient to prevent chromosomal position effects that inhibit transgene expression.
Caterina
J J
JJ
Department of Biochemistry and Molecular Genetics, School of Medicine, University of Alabama at Birmingham 35294.
Ciavatta
D J
DJ
Donze
D
D
Behringer
R R
RR
Townes
T M
TM
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D017353:Gene Deletion; D015870:Gene Expression; D005914:Globins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D012045:Regulatory Sequences, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D051720:Upstream Stimulatory Factors
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; C494689:Gata1 protein, mouse; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; C494693:Nfe2 protein, mouse; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; C497183:Usf1 protein, mouse; D005914:Globins; D003850:Deoxyribonuclease I