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The cell cycle in polyploid megakaryocytes is associated with reduced activity of cyclin B1-dependent cdc2 kinase

Zhang, Y ; Wang, Z ; Ravid, K

The Journal of biological chemistry, 23 February 1996, Vol.271(8), pp.4266-72 [Tạp chí có phản biện]

ISSN: 0021-9258 ; PMID: 8626773 Version:1

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  • Nhan đề:
    The cell cycle in polyploid megakaryocytes is associated with reduced activity of cyclin B1-dependent cdc2 kinase
  • Tác giả: Zhang, Y ; Wang, Z ; Ravid, K
  • Chủ đề: Cell Cycle ; Cyclin B ; DNA Replication ; Cdc2 Protein Kinase -- Metabolism ; Cyclins -- Biosynthesis ; Megakaryocytes -- Cytology
  • Là 1 phần của: The Journal of biological chemistry, 23 February 1996, Vol.271(8), pp.4266-72
  • Mô tả: The platelet precursor, the megakaryocyte, matures to a polyploid cell as a result of DNA replication in the absence of mitosis (endomitosis). The factors controlling endomitosis are accessible to analysis in our megakaryocytic cell line, MegT, generated by targeted expression of temperature-sensitive simian virus 40 large T antigen to megakaryocytes of transgenic mice. We aimed to define whether endomitosis consists of a continuous phase of DNA synthesis (S) or of S phases interrupted by gaps. Analysis of the cell cycle in MegT cells revealed that, upon inactivation of large T antigen, the cells shifted from a mitotic cell cycle to an endomitotic cell cycle consisting of S/Gap phases. The level of the G1/S cyclin, cyclin A, as well as of the G1 phase cyclin, cyclin D3, were elevated at the onset of DNA synthesis, either in MegT cells undergoing a mitotic cell cycle or during endomitosis. In contrast, the level of the mitotic cyclin, cyclin B1, cycled in cells displaying a mitotic cell cycle while not detectable during endomitosis. Comparable levels of the mitotic kinase protein, Cdc2, were detected during the mitotic cell cycle or during endomitosis; however, cyclin B1-dependent Cdc2 kinase activity was largely abolished in the polyploid cells. Fibroblasts immortalized with the same heat-labile oncogene do not display reduced levels of cyclin B1 upon shifting to high temperature nor do they become polyploid, indicating that reduced levels of cyclin B1 is a property of megakaryocytes and not of the T-antigen mutant. We conclude that cellular programming during endoreduplication in megakaryocytes is associated with reduced levels of cyclin B1.
  • Ngôn ngữ: English
  • Số nhận dạng: ISSN: 0021-9258 ; PMID: 8626773 Version:1

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