Krasinska Liliana, de Bettignies Geoffroy, Fisher Daniel, Abrieu Ariane, Fesquet Didier, Morin Nathalie
Centre de Recherches de Biochimie Macromoleculaire, Université Montpellier II, CNRS UMR5237 1919, Route de Mende, 34293 Montpellier Cedex 5, France.
Exp Cell Res. 2007 Apr 1;313(6):1225-39. doi: 10.1016/j.yexcr.2006.12.022. Epub 2007 Jan 10.
Whereas early cytokinesis events have been relatively well studied, little is known about its final stage, abscission. The Cdc14 phosphatase is involved in the regulation of multiple cell cycle events, and in all systems studied Cdc14 misexpression leads to cytokinesis defects. In this work, we have cloned two CDC14 cDNA from Xenopus, including a previously unreported CDC14B homologue. We use Xenopus and human cell lines and demonstrate that localization of Cdc14 proteins is independent of both cell-type and species specificity. Ectopically expressed XCdc14A is centrosomal in interphase and localizes to the midbody in cytokinesis. By using XCdc14A misregulation, we confirm its control over different cell cycle events and unravel new functions during abscission. XCdc14A regulates the G1/S and G2/M transitions. We show that Cdc25 is an in vitro substrate for XCdc14A and might be its target at the G2/M transition. Upregulated wild-type or phosphatase-dead XCdc14A arrest cells in a late stage of cytokinesis, connected by thin cytoplasmic bridges. It does not interfere with central spindle formation, nor with the relocalization of passenger protein and centralspindlin complexes to the midbody. We demonstrate that XCdc14A upregulation prevents targeting of exocyst and SNARE complexes to the midbody, both essential for abscission to occur.
尽管早期胞质分裂事件已得到相对充分的研究，但其最后阶段——分裂却鲜为人知。Cdc14磷酸酶参与多种细胞周期事件的调控，在所有已研究的系统中，Cdc14表达异常均会导致胞质分裂缺陷。在本研究中，我们从非洲爪蟾中克隆了两个CDC14 cDNA，其中包括一个此前未报道的CDC14B同源物。我们利用非洲爪蟾和人类细胞系，证明Cdc14蛋白的定位与细胞类型和物种特异性均无关。异位表达的XCdc14A在间期定位于中心体，在胞质分裂时定位于中间体。通过对XCdc14A的表达失调研究，我们证实了它对不同细胞周期事件的控制，并揭示了其在分裂过程中的新功能。XCdc14A调控G1/S期和G2/M期转换。我们发现Cdc25是XCdc14A的体外底物，可能是其在G2/M期转换时的作用靶点。上调野生型或磷酸酶失活型的XCdc14A会使细胞停滞在胞质分裂后期，细胞由细的细胞质桥相连。它既不干扰中央纺锤体的形成，也不影响乘客蛋白和中央纺锤体复合物重新定位于中间体。我们证明，上调XCdc14A可阻止外泌体和SNARE复合物定位于中间体，而这两者对于分裂的发生都是必不可少的。
