title: Characterization of combinatorial histone modifications on lineage-affiliated genes during hematopoietic stem cell myeloid commitment.
abstract: Hematopoietic stem cells (HSCs) are multipotent stem cells capable of self-renewal and multilineage differentiation. Mechanisms regulating the maintenance of HSCs' multipotency and differentiation are still unclear. In this study, we observed the role of combinatorial histone modification pattern in the maintenance of HSCs' pluripotency and differentiation. HSCs (CD34(+)CD38(low)) were collected from human umbilical cord blood and induced to differentiate to committed cells in vitro. The histone modifications on lineage-specific transcription factors/genes in multipotent HSCs and differentiated progenies, including megakaryocytes, granulocytes, and erythrocytes, were analyzed by chromatin immunoprecipitation-quantitative polymerase chain reaction. Our results showed that a certain level of acH4 and acH3 together with high level of H3K4me2, low level of H3K4me3, and a certain level of H3K9me3 and H3K27me3 were present in lineage-specific genes in CD34(+)CD38(low) HSCs. As CD34(+)CD38(low) cells differentiated into granulocytes, erythroid cells, and megakaryocytes, the modification levels of acH3, acH4, and H3K4me2 on lineage-specific genes remained the same or elevated, while H3K4me3 level was increased greatly. At the same time, H3K9me3 and H3K27me3 modification levels became lower. In non-lineage-specific genes, the acH3 and acH4 levels were decreased, and H3K4me3 level remained at low level, while H3K9me3 and H3K27me3 levels were increased drastically. Our data suggest that combinatorial histone modification patterns have implicated function in maintaining the multipotency of HSCs and keeping the accuracy of gene expression program during HSC differentiation.
authors.affiliation: Department of Radiation Therapy, Zhejiang Key Laboratory of Radiation Oncology, Zhejiang Cancer Hospital, Hangzhou 310022, China Department of Hematology, Third Xiangya Hospital, Central South University, Changsha 410013, China.
authors.forename: Huarong
authors.initials: H
authors.lastname: Tang
authors.affiliation: Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
authors.forename: Shimin
authors.initials: S
authors.lastname: An
authors.affiliation: Department of Physiology, Central South University, Xiangya School of Medicine, Changsha 410013, China.
authors.forename: Huanying
authors.initials: H
authors.lastname: Zhen
authors.affiliation: Department of Hematology, Third Xiangya Hospital, Central South University, Changsha 410013, China xychenfp@2118.com.
authors.forename: Fangping
authors.initials: F
authors.lastname: Chen
mesh_terms: D015703:Antigens, CD / Q000276:immunology; D019070:Cell Lineage / Q000235:genetics*; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques
chemical_list: D015703:Antigens, CD; D006657:Histones
keywords: hematopoietic stem cells; histone modification; lineage-affiliated genes; myeloid commitment