Novel alterations in CDK1/cyclin B1 kinase complex formation occur during the acquisition of a polyploid DNA content
Novel alterations in CDK1/cyclin B1 kinase complex formation occur during the acquisition of a polyploid DNA content
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DOI：
10.1091/mbc.7.2.209
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发表时间：
1996-02-01
影响因子：
3.3
通讯作者：
Long, MW
中科院分区：
文献类型：
--
作者：
Datta, NS;Williams, JL;Long, MW
调节与DNA复制控制相关的S期事件的途径知之甚少。骨髓巨核细胞的独特之处在于它们离开二倍体（2C）状态进行分化，在单个核内合成4至64倍的正常DNA含量，这一过程称为核内有丝分裂。人红白血病（HEL）细胞模型这一过程中，成为多倍体佛波醇二酯诱导的巨核细胞分化。这些多倍体细胞中发生的有丝分裂停滞涉及cdk 1/细胞周期蛋白B1复合物的新变化：cdk 1蛋白水平显着降低，以及细胞周期蛋白B1表达的升高和持续。因此，内有丝分裂细胞缺乏cdk 1/细胞周期蛋白B1相关的H1-组蛋白激酶活性。组成性过表达的cdk 1在有丝分裂细胞内未能重新启动正常的有丝分裂事件，即使cdk 1是目前在10倍过量。这是由于细胞周期蛋白-B1不能与cdk 1物理结合。尽管如此，有丝分裂细胞周期蛋白B1具有免疫沉淀H1-组蛋白激酶活性，并特异性易位到细胞核。我们的结论是，有丝分裂被废除，由于缺乏cdk 1和未能形成M期促进因子，导致有丝分裂从完成S期的解离在有丝分裂过程中。对细胞周期蛋白及其相互作用蛋白的进一步研究将有助于我们更好地理解细胞内有丝分裂和细胞周期调控。
The pathways that regulate the S-phase events associated with the control of DNA replication are poorly understood. The bone marrow megakaryocytes are unique in that they leave the diploid (2C) state to differentiate, synthesizing 4 to 64 times the normal DNA content within a single nucleus, a process known as endomitosis. Human erythroleukemia (HEL) cells model this process, becoming polyploid during phorbol diester-induced megakaryocyte differentiation. The mitotic arrest occurring in these polyploid cells involves novel alterations in the cdk1/cyclin B1 complex: a marked reduction in cdk1 protein levels, and an elevated and sustained expression of cyclin B1. Endomitotic cells thus lack cdk1/cyclin B1-associated H1-histone kinase activity. Constitutive overexpression of cdk1 in endomitotic cells failed to re-initiate normal mitotic events even though cdk1 was present in a 10-fold excess. This was due to an inability of cyclin-Bl to physically associate with cdk1. Nonetheless, endomitotic cyclin B1 possesses immunoprecipitable H1-histone kinase activity, and specifically translocates to the nucleus. We conclude that mitosis is abrogated during endomitosis due to the absence of cdk1 and the failure to form M-phase promoting factor, resulting in a disassociation of mitosis from the completion of S-phase. Further studies on cyclin and its interacting proteins should be informative in understanding endomitosis and cell cycle control.