title: Transcriptional environment and chromatin architecture interplay dictates globin expression patterns of heterospecific hybrids derived from undifferentiated human embryonic stem cells or from their erythroid progeny.
abstract: To explore the response of β globin locus with established chromatin domains upon their exposure to new transcriptional environments, we transferred the chromatin-packaged β globin locus of undifferentiated human embryonic stem cells (hESCs) or hESC-derived erythroblasts into an adult transcriptional environment. Distinct globin expression patterns were observed. In hESC-derived erythroblasts where both ε and γ globin were active and marked by similar chromatin modifications, ε globin was immediately silenced upon transfer, whereas γ globin continued to be expressed for months, implying that different transcriptional environments were required for their continuing expression. Whereas β globin was silent both in hESCs and in hESC-derived erythroblasts, β globin was only activated upon transfer from hESCs, but not in the presence of dominant γ globin transferred from hESC-derived erythroblasts, confirming the competing nature of γ versus β globin expression. With time, however, silencing of γ globin occurred in the adult transcriptional environment with concurrent activation of β-globin, accompanied by a drastic change in the epigenetic landscape of γ and β globin gene regions without apparent changes in the transcriptional environment. This switching process could be manipulated by overexpression or downregulation of certain transcription factors. Our studies provide important insights into the interplay between the transcription environment and existing chromatin domains, and we offer an experimental system to study the time-dependent human globin switching.
authors.affiliation: Division of Hematology, Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Kai-Hsin
authors.initials: KH
authors.lastname: Chang
authors.forename: Andy
authors.initials: A
authors.lastname: Huang
authors.forename: Hemei
authors.initials: H
authors.lastname: Han
authors.forename: Yi
authors.initials: Y
authors.lastname: Jiang
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Fang
authors.forename: Chao-Zhong
authors.initials: CZ
authors.lastname: Song
authors.forename: Steve
authors.initials: S
authors.lastname: Padilla
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Hongzhu
authors.initials: H
authors.lastname: Qu
authors.forename: John
authors.initials: J
authors.lastname: Stamatoyannopoulos
authors.forename: Qiliang
authors.initials: Q
authors.lastname: Li
authors.forename: Thalia
authors.initials: T
authors.lastname: Papayannopoulou
mesh_terms: D000328:Adult; D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins; D000077209:Decitabine; D004622:Embryo, Mammalian / Q000166:cytology; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D004900:Erythroblasts / Q000166:cytology / Q000378:metabolism; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005914:Globins / Q000235:genetics*; D006801:Humans; D006822:Hybrid Cells; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D034622:RNA Interference; D012097:Repressor Proteins; D013997:Time Factors; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics; D055544:beta-Globins / Q000235:genetics; D055547:epsilon-Globins / Q000235:genetics; D055545:gamma-Globins / Q000235:genetics
chemical_list: C407733:Bcl11a protein, mouse; D002352:Carrier Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D055544:beta-Globins; D055547:epsilon-Globins; D055545:gamma-Globins; D000077209:Decitabine; D005914:Globins; D001374:Azacitidine