title: Presence of a defect in karyokinesis during megakaryocyte endomitosis.
abstract: Megakaryocyte is the naturally polyploid cell that gives rise to platelets. Polyploidization occurs by endomitosis, a process corresponding to a late failure of cytokinesis with a backward movement of the daughter cells. Generally, a pure defect in cytokinesis produces a multinucleated cell, but megakaryocytes are characterized by a single polylobulated nucleus with a 2 (N)  ploidy. Here, we show the existence of a defect in karyokinesis during the endomitotic process. From late telophase until the reversal of cytokinesis, some dipolar mitosis/endomitosis and most multipolar endomitosis present a thin DNA link between the segregated chromosomes surrounded by an incomplete nuclear membrane formation, which implies that sister chromatid separation is not complete. This observation may explain why polyploid megakaryocytes display a single polylobulated nucleus along with an increase in ploidy.
authors.affiliation: INSERM, UMR 1009, Institut Gustave Roussy, Villejuif, France.
authors.forename: Larissa
authors.initials: L
authors.lastname: Lordier
authors.forename: Jiajia
authors.initials: J
authors.lastname: Pan
authors.forename: Valeria
authors.initials: V
authors.lastname: Naim
authors.forename: Abdelali
authors.initials: A
authors.lastname: Jalil
authors.forename: Idinath
authors.initials: I
authors.lastname: Badirou
authors.forename: Philippe
authors.initials: P
authors.lastname: Rameau
authors.forename: Jerôme
authors.initials: J
authors.lastname: Larghero
authors.forename: Najet
authors.initials: N
authors.lastname: Debili
authors.forename: Filippo
authors.initials: F
authors.lastname: Rosselli
authors.forename: William
authors.initials: W
authors.lastname: Vainchenker
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Chang
mesh_terms: D018952:Antigens, CD34 / Q000378:metabolism; D048750:Cell Nucleus Division; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology* / Q000378:metabolism; D018613:Microscopy, Confocal; D008938:Mitosis; D013692:Telophase
chemical_list: D018952:Antigens, CD34