Reduced beta-globin gene expression in adult mice containing deletions of locus control region 5' HS-2 or 5' HS-3.
To gain insights into the functions of individual DNA'se hypersensitive sites within the beta globin locus control region (LCR), we deleted the endogenous 5' HS-2 and HS-3 regions from the mouse germline using homologous recombination techniques. We demonstrated that the deletion of either murine 5' HS-2 or 5' HS-3 reduced the expression of the embryonic epsilon y and beta h1 globin genes minimally in yolk sac-derived erythrocytes, but that both knockouts reduced the output of the adult beta (beta-Major + beta-Minor) globin genes by approximately 30% in adult erythrocytes. When the selectable marker PGK-Neo cassette was retained within either the HS-2 or HS-3 region, a much more severe reduction in globin gene expression was observed at all developmental stages. PGK-Neo was shown to be expressed in an erythroid-specific fashion when it was retained in the HS-3 position. These results show that neither 5' HS-2 nor HS-3 is required for the activity of embryonic globin genes, nor are these sites required for correct developmental switching. However, each site is required for approximately 30% of the total LCR activity associated with adult beta-globin gene expression in adult red blood cells. Each site therefore contains some non-redundant information that contributes to adult globin gene function.
Washington University School of Medicine, Department of Internal Medicine, St. Louis, Missouri 63110-1093, USA. timley@im.wustl.edu
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D000818:Animals; D003433:Crosses, Genetic; D005260:Female; D005313:Fetal Death; D005914:Globins / Q000096:biosynthesis* / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D019901:Locus Control Region; D008297:Male; D051379:Mice; D005810:Multigene Family; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011995:Recombination, Genetic; D017384:Sequence Deletion
D011993:Recombinant Fusion Proteins; D005914:Globins