Actopaxin is phosphorylated during mitosis and is a substrate for cyclin B1/cdc2 kinase
Actopaxin is phosphorylated during mitosis and is a substrate for cyclin B1/cdc2 kinase
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DOI：
10.1042/0264-6021:3630233
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发表时间：
2002-04-15
影响因子：
4.1
通讯作者：
Turner, CE
中科院分区：
文献类型：
--
作者：
Curtis, M;Nikolopoulos, SN;Turner, CE
在细胞分裂之前，正常的贴壁细胞采用圆形形态，这与肌动蛋白应力纤维的损失和粘着斑的分解有关。在这项研究中，我们研究了最近描述的桩蛋白和肌动蛋白结合的局灶性粘附蛋白actopaxin的有丝分裂磷酸化[Nikolopoulos和Turner（2000）J. Cell Biol.151，1435-1448]。Actopaxin由含有6个推定的cdc 2磷酸化位点的N-末端和由串联的钙调蛋白同源结构域组成的C-末端组成。在这里，我们表明，N-末端的actopaxin是磷酸化的细胞周期蛋白B1/cdc 2激酶在体外，这一地区的actopaxin沉淀cdc 2激酶活性从有丝分裂裂解物。Actopaxin在有丝分裂过程中表现出降低的电泳迁移率，这依赖于前两个共有cdc 2磷酸化位点内的磷酸化。最后，随着细胞从有丝分裂到G（1）期，有一个不依赖于粘附的actopaxin去磷酸化，表明actopaxin去磷酸化先于细胞扩散和局部粘附的重新形成。两者合计，这些结果表明细胞周期蛋白B1/cdc 2依赖的actopaxin磷酸化在调节细胞分裂过程中肌动蛋白细胞骨架重组的作用。
Prior to cell division, normal adherent cells adopt a round morphology that is associated with a loss of actin stress fibres and disassembly of focal adhesions. In this study, we investigate the mitotic phosphorylation of the recently described paxillin and actin-binding focal-adhesion protein actopaxin [Nikolopoulos and Turner (2000) J. Cell Biol. 151, 1435-1448]. Actopaxin is comprised of an N-terininus containing six putative cdc2 phosphorylation sites and a C-terminus consisting of tandem calponin homology domains. Here we show that the N-terminus of actopaxin is phosphorylated by cyclin B1/cdc2 kinase in vitro and that this region of actopaxin precipitates cdc2 kinase activity from mitotic lysates. Actopaxin exhibits reduced electrophoretic mobility during mitosis that is dependent on phosphorylation within the first two consensus cdc2 phosphorylation sites. Finally, as cells progress from mitosis to G(1) there is an adhesion-independent dephosphorylation of actopaxin, suggesting that actopaxin dephosphorylation precedes cell spreading and the reformation of focal adhesions. Taken together, these results suggest a role for cyclin B1/cdc2-dependent phosphorylation of actopaxin in regulating actin cytoskeleton reorganization during cell division.