title: Erythroblast enucleation is a dynein-dependent process.
abstract: Mammalian erythroblasts undergo enucleation through a process thought to be similar to cytokinesis. Microtubule-organizing centers (MTOCs) mediate organization of the mitotic spindle apparatus that separates the chromosomes during mitosis and are known to be crucial for proper cytokinesis. However, the role of MTOCs in erythroblast enucleation remains unknown. We therefore investigated the effect of various MTOC inhibitors on cytokinesis and enucleation using human colony-forming units-erythroid (CFU-Es) and mature erythroblasts generated from purified CD34(+) cells. We found that erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA), a dynein inhibitor, and monastrol, a kinesin Eg5 inhibitor, as well as various inhibitors of MTOC regulators, including ON-01910 (Plk-1), MLN8237 (aurora A), hesperadin (aurora B), and LY294002 (PI3K), all inhibited CFU-E cytokinesis. Among these inhibitors, however, only EHNA blocked enucleation. Moreover, terminally differentiated erythroblasts expressed only dynein; little or none of the other tested proteins was detected. Over the course of the terminal differentiation of human erythroblasts, the fraction of cells with nuclei at the cell center declined, whereas the fraction of polarized cells, with nuclei shifted to a position near the plasma membrane, increased. Dynein inhibition impaired nuclear polarization, thereby blocking enucleation. These data indicate that dynein plays an essential role not only in cytokinesis but also in enucleation. We therefore conclude that human erythroblast enucleation is a process largely independent of MTOCs, but dependent on dynein.
authors.affiliation: Department of Hematology, Nephrology, and Rheumatology, Graduate School of Medicine, Akita University, Akita, Japan.
authors.forename: Isuzu
authors.initials: I
authors.lastname: Kobayashi
authors.affiliation: Department of Hematology, Nephrology, and Rheumatology, Graduate School of Medicine, Akita University, Akita, Japan.
authors.forename: Kumi
authors.initials: K
authors.lastname: Ubukawa
authors.affiliation: Department of Hematology, Nephrology, and Rheumatology, Master Course of Graduate School of Medicine, Akita University, Akita, Japan.
authors.forename: Kotomi
authors.initials: K
authors.lastname: Sugawara
authors.affiliation: Center for Radio Isotope, Akita University, Akita, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Asanuma
authors.affiliation: Department of Hematology, Nephrology, and Rheumatology, Graduate School of Medicine, Akita University, Akita, Japan.
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Guo
authors.affiliation: Center for Radio Isotope, Akita University, Akita, Japan.
authors.forename: Junsuke
authors.initials: J
authors.lastname: Yamashita
authors.affiliation: Department of Hematology, Nephrology, and Rheumatology, Graduate School of Medicine, Akita University, Akita, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Takahashi
authors.affiliation: Akita University, Akita, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sawada
authors.affiliation: Research Center for Science, Graduate School of Engineering and Resource Science, Akita University, Akita, Japan; Department of Life Science, Graduate School of Engineering and Resource Science, Akita University, Akita, Japan. Electronic address: nunomura@gipc.akita-u.ac.jp.
authors.forename: Wataru
authors.initials: W
authors.lastname: Nunomura
mesh_terms: D002454:Cell Differentiation; D002455:Cell Division / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004398:Dyneins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004900:Erythroblasts / Q000166:cytology* / Q000378:metabolism*; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004920:Erythropoiesis; D015870:Gene Expression; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D022101:Microtubule-Organizing Center / Q000378:metabolism; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology; D014404:Tubulin / Q000235:genetics / Q000378:metabolism
chemical_list: D020409:Molecular Motor Proteins; D013450:Sulfones; D014404:Tubulin; C507134:ON 01910; D004398:Dyneins; D005998:Glycine