Deletion of the human beta-globin LCR 5'HS4 or 5'HS1 differentially affects beta-like globin gene expression in beta-YAC transgenic mice.
A 213 kb human beta-globin locus yeast artificial chromosome (beta-YAC) was modified by homologous recombination to delete 2.9 kb of cross-species conserved sequence similarity encompassing the LCR 5' hypersensitive site (HS) 4 (Delta5'HS4 beta-YAC). In three transgenic mouse lines, completion of the gamma- to beta-globin switch during definitive erythropoiesis was delayed relative to wild-type beta-YAC mice. In addition, quantitative per-copy human beta-like globin mRNA levels were similar to wild-type beta-YAC transgenic lines, although beta-globin gene expression was slightly decreased in the day 12 fetal liver of Delta5'HS4 beta-YAC mice. A 0.8 kb 5'HS1 fragment was similarly deleted in the YAC. Three Delta5'HS1 beta-YAC transgenic lines were established. epsilon-globin gene expression was markedly reduced, approximately 16 fold, during primitive erythropoiesis compared to wild-type beta-YAC mice, but gamma-globin expression levels were unaffected. However, during the fetal stage of definitive erythropoiesis, gamma-globin gene expression was decreased approximately 4 fold at day 12 and approximately 5 fold at day 14. Temporal developmental expression profiles of the beta-like globin genes were unaffected by deletion of 5'HS1. Decreased expression of the epsilon- and gamma-globin genes is the first phenotype ascribed to a 5'HS1 mutation in the human beta-globin locus, suggesting that this HS does indeed have a role in LCR function beyond simply a combined synergism with the other LCR HSs.
Fedosyuk
Halyna
H
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
Peterson
Kenneth R
KR
D000818:Animals; D001483:Base Sequence; D018244:Chromosomes, Artificial, Yeast; D004920:Erythropoiesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D005914:Globins / Q000235:genetics*; D006801:Humans; D019901:Locus Control Region / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D017384:Sequence Deletion
D005914:Globins