Effects of human locus control region elements HS2 and HS3 on human beta-globin gene expression in transgenic mouse.
The locus control region (LCR) is the most important cis-element in the regulation of beta-globin gene expression. DNaseI-hypersensitive site (HS) 2 and HS3 are two significant components of beta-LCR. To examine the effect of HS2, HS3, and HS2-HS3 (combination of HS2 and HS3) on the spatial and temporal expression of the human beta-globin gene, we have produced transgenic mice with constructs, in which the gene encoding enhanced green fluorescent protein (EGFP) is driven by beta-globin promoter and under the control of HS2, HS3, and HS2-HS3, respectively. The results showed that HS2 and HS3 each had the same enhancement activity in regulation of beta-globin gene expression in transgenic mice. When HS2 and HS3 were in combination (HS2-HS3), the two cis-elements showed a marked synergy in regulating beta-globin gene spatial and temporal expression as well as its expression level in transgenic mice although the EGFP expression varied largely among different transgenic mouse litters. The results also showed that HS2 was able to confer beta-globin gene expression in embryonic yolk sac, fetal liver, and adult bone marrow, which was not developmentally stage-specific, while HS3 could confer the same beta-globin gene expression in the adult. Thus, HS3 was different from HS2, the former being more important for specific expression of beta-globin gene in the developmental stages and the switch of gamma-->beta-globin genes. Our results indicate that the mechanism of gamma-->beta switch could be best explained by the "divided model."
Jia
Chun-Ping
CP
Shanghai Institute of Medical Genetics, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 200040, People's Republic of China.
Huang
Shu-Zhen
SZ
Yan
Jing-Bin
JB
Xiao
Yan-Ping
YP
Ren
Zhao-Rui
ZR
Zeng
Yi-Tao
YT
D000375:Aging / Q000235:genetics; D000818:Animals; D004622:Embryo, Mammalian / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter / Q000235:genetics; D005914:Globins / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D019901:Locus Control Region / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019076:Transgenes / Q000235:genetics*
D012333:RNA, Messenger; D005914:Globins