Zimmet J, Ravid K
Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Mass. 02118, USA.
Exp Hematol. 2000 Jan;28(1):3-16. doi: 10.1016/s0301-472x(99)00124-1.
Polyploidy, the state of having greater than the diploid content of DNA, has been recognized in a variety cells. Among these cell types, the megakaryocytes are classified as obligate polyploid cells, developing a polyploid DNA content regularly during the normal life cycle of the organism, while other cells may become polyploid only in response to certain stimuli. The objective of this review is to briefly describe the different cell cycle alterations that may lead to high ploidy, while focusing on the megakaryocyte and the importance of high ploidy to platelet level and function.
Relevant articles appearing in scientific journals and books published in the United States and in Europe during the years 1910-1999 were used as resources for this review. We selected fundamental studies related to cell cycle regulation as well as studies relevant to the regulation of the endomitotic cell cycle in megakaryocytes. Also surveyed were publications describing the relevance of high ploidy to high platelet count and to platelet reactivity, in normal situations and in a disease state.
Different cells may achieve polyploidy through different alterations in the cell cycle machinery.
While upregulation of cyclin D3 further augments ploidy in polyploidizing megakaryocytes in vivo, future investigation should aim to explore how normal megakaryocytes may initiate the processes of skipping late anaphase and cytokinesis associated with high ploidy. In humans, under normal conditions, megakaryocyte ploidy correlates with platelet volume, and large platelets are highly reactive. This may not apply, however, to the disease state.
多倍体是指具有超过二倍体DNA含量的状态，已在多种细胞中被识别。在这些细胞类型中，巨核细胞被归类为专性多倍体细胞，在生物体的正常生命周期中定期形成多倍体DNA含量，而其他细胞可能仅在对某些刺激作出反应时才会变成多倍体。本综述的目的是简要描述可能导致高倍性的不同细胞周期改变，同时重点关注巨核细胞以及高倍性对血小板水平和功能的重要性。
1910年至1999年间在美国和欧洲出版的科学期刊和书籍中出现的相关文章被用作本综述的资源。我们选择了与细胞周期调控相关的基础研究以及与巨核细胞内有丝分裂细胞周期调控相关的研究。还调查了描述在正常情况和疾病状态下高倍性与高血小板计数及血小板反应性相关性的出版物。
不同细胞可能通过细胞周期机制的不同改变实现多倍体化。
虽然细胞周期蛋白D3的上调在体内进一步增加了正在多倍体化的巨核细胞的倍性，但未来的研究应旨在探索正常巨核细胞如何启动与高倍性相关的后期和胞质分裂跳过过程。在人类中，在正常情况下，巨核细胞倍性与血小板体积相关，并且大血小板具有高反应性。然而，这可能不适用于疾病状态。
