title: Potential of CD34 in the regulation of symmetrical and asymmetrical divisions by hematopoietic progenitor cells.
abstract: The control of symmetric and asymmetric division in the hematopoietic stem/progenitor cell population is critically important for the regulation of blood cell production. Asymmetric divisions depend on cell polarization, which may be conferred by location and/or interaction with neighboring cells. In this study, we sought evidence for polarization in CD34+ cells, which interact by binding to one another. In these cells, surface molecules became redistributed by mechanisms that included transport by lipid rafts, and the interacting cells were able to communicate via gap junctions. These changes were accompanied by modulation of cell cycle regulating proteins (p16(Ink4a), p27(kip1), cyclins D, and the retinoblastoma pathway proteins) and a reduction in progenitor cell proliferation in vitro. These results are consistent with an increase in asymmetric cell division kinetics. Accordingly, we found that interaction between CD34+ cells influenced the plane of cell division in a way that suggests unequal sharing of Notch-1 between daughter cell progeny. We conclude that interaction between CD34+ cells may coordinate cell function and participate in the control of hematopoietic stem/progenitor cell division kinetics.
authors.affiliation: Department of Haematology, Imperial College Faculty of Medicine, Hammersmith Campus, London, United Kingdom.
authors.forename: Tabitha E
authors.initials: TE
authors.lastname: Bullock
authors.forename: Baiping
authors.initials: B
authors.lastname: Wen
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Marley
authors.forename: Myrtle Y
authors.initials: MY
authors.lastname: Gordon
mesh_terms: D015703:Antigens, CD / Q000502:physiology; D018952:Antigens, CD34 / Q000502:physiology*; D002449:Cell Aggregation; D002453:Cell Cycle; D002455:Cell Division; D017629:Gap Junctions / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D016169:Lymphocyte Function-Associated Antigen-1 / Q000502:physiology; D021962:Membrane Microdomains / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D014019:Tissue Donors
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D016169:Lymphocyte Function-Associated Antigen-1; D034741:RNA, Small Interfering