title: Chromatin architecture near a potential 3' end of the igh locus involves modular regulation of histone modifications during B-Cell development and in vivo occupancy at CTCF sites.
abstract: The murine Igh locus has a 3' regulatory region (3' RR) containing four enhancers (hs3A, hs1,2, hs3B, and hs4) at DNase I-hypersensitive sites. The 3' RR exerts long-range effects on class switch recombination (CSR) to several isotypes through its control of germ line transcription. By measuring levels of acetylated histones H3 and H4 and of dimethylated H3 (K4) with chromatin immunoprecipitation assays, we found that early in B-cell development, chromatin encompassing the enhancers of the 3' RR began to attain stepwise modifications typical of an open conformation. The hs4 enhancer was associated with active chromatin initially in pro- and pre-B cells and then together with hs3A, hs1,2, and hs3B in B and plasma cells. Histone modifications were similar in resting splenic B cells and in splenic B cells induced by lipopolysaccharide to undergo CSR. From the pro-B-cell stage onward, the approximately 11-kb region immediately downstream of hs4 displayed H3 and H4 modifications indicative of open chromatin. This region contained newly identified DNase I-hypersensitive sites and several CTCF target sites, some of which were occupied in vivo in a developmentally regulated manner. The open chromatin environment of the extended 3' RR in mature B cells was flanked by regions associated with dimethylated K9 of histone H3. Together, these data suggest that 3' RR elements are located within a specific chromatin subdomain that contains CTCF binding sites and developmentally regulated modules.
authors.affiliation: Albert Einstein College of Medicine, Department of Cell Biology, Bronx, NY 10461, USA.
authors.forename: Francine E
authors.initials: FE
authors.lastname: Garrett
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Emelyanov
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Sepulveda
authors.forename: Patrick
authors.initials: P
authors.lastname: Flanagan
authors.forename: Sabrina
authors.initials: S
authors.lastname: Volpi
authors.forename: Fubin
authors.initials: F
authors.lastname: Li
authors.forename: Dmitry
authors.initials: D
authors.lastname: Loukinov
authors.forename: Laurel A
authors.initials: LA
authors.lastname: Eckhardt
authors.forename: Victor V
authors.initials: VV
authors.lastname: Lobanenkov
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Birshtein
mesh_terms: D024509:3' Flanking Region / Q000235:genetics*; D000107:Acetylation / Q000187:drug effects; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D001853:Bone Marrow / Q000276:immunology / Q000378:metabolism; D000076246:CCCTC-Binding Factor; D002843:Chromatin / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics; D006657:Histones / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017578:Immunoglobulin Class Switching / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D019901:Locus Control Region / Q000235:genetics; D051379:Mice; D012097:Repressor Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013154:Spleen / Q000276:immunology / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D000076246:CCCTC-Binding Factor; D002843:Chromatin; C000619698:Ctcf protein, mouse; D017931:DNA Primers; D004268:DNA-Binding Proteins; D006657:Histones; D008070:Lipopolysaccharides; D012097:Repressor Proteins; D003850:Deoxyribonuclease I