Synergistic and additive properties of the beta-globin locus control region (LCR) revealed by 5'HS3 deletion mutations: implication for LCR chromatin architecture.
Deletion of the 234-bp core element of the DNase I hypersensitive site 3 (5'HS3) of the locus control region (LCR) in the context of a human beta-globin locus yeast artificial chromosome (beta-YAC) results in profound effects on globin gene expression in transgenic mice. In contrast, deletion of a 2.3-kb 5'HS3 region, which includes the 234-bp core sequence, has a much milder phenotype. Here we report the effects of these deletions on chromatin structure in the beta-globin locus of adult erythroblasts. The 234-bp 5'HS3 deletion abolished histone acetylation throughout the beta-globin locus; recruitment of RNA polymerase II (pol II) to the LCR and beta-globin gene promoter was reduced to a basal level; and formation of all the 5' DNase I hypersensitive sites of the LCR was disrupted. The 2.3-kb 5'HS3 deletion mildly reduced the level of histone acetylation but did not change the profile across the whole locus; the 5' DNase I hypersensitive sites of the LCR were formed, but to a lesser extent; and recruitment of pol II was reduced, but only marginally. These data support the hypothesis that the LCR forms a specific chromatin structure and acts as a single entity. Based on these results we elaborate on a model of LCR chromatin architecture which accommodates the distinct phenotypes of the 5'HS3 and HS3 core deletions.
Fang
Xiangdong
X
Medical Genetics, University of Washington, Seattle, 98195, USA.
Sun
Jin
J
Xiang
Ping
P
Yu
Man
M
Navas
Patrick A
PA
Peterson
Kenneth R
KR
Stamatoyannopoulos
George
G
Li
Qiliang
Q
D000107:Acetylation; D000818:Animals; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D004900:Erythroblasts / Q000378:metabolism; D050981:Erythroid-Specific DNA-Binding Factors; D017353:Gene Deletion; D005914:Globins / Q000235:genetics*; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D019901:Locus Control Region; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D010641:Phenotype; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D002843:Chromatin; D017931:DNA Primers; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D006657:Histones; D014157:Transcription Factors; D005914:Globins; D004247:DNA; D012319:RNA Polymerase II; D003850:Deoxyribonuclease I