Tavernier Nicolas, Noatynska Anna, Panbianco Costanza, Martino Lisa, Van Hove Lucie, Schwager Françoise, Léger Thibaut, Gotta Monica, Pintard Lionel
Jacques Monod Institute, UMR7592; and Mass Spectrometry Facility, Jacques Monod Institute, UMR7592; Paris-Diderot University-Centre National de la Recherche Scientifique, 75013 Paris, France.
Department of Cellular Physiology and Metabolism, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland.
J Cell Biol. 2015 Mar 16;208(6):661-9. doi: 10.1083/jcb.201408064. Epub 2015 Mar 9.
The molecular mechanisms governing mitotic entry during animal development are incompletely understood. Here, we show that the mitotic kinase CDK-1 phosphorylates Suppressor of Par-Two 1 (SPAT-1)/Bora to regulate its interaction with PLK-1 and to trigger mitotic entry in early Caenorhabditis elegans embryos. Embryos expressing a SPAT-1 version that is nonphosphorylatable by CDK-1 and that is defective in PLK-1 binding in vitro present delays in mitotic entry, mimicking embryos lacking SPAT-1 or PLK-1 functions. We further show that phospho-SPAT-1 activates PLK-1 by triggering phosphorylation on its activator T loop in vitro by Aurora A. Likewise, we show that phosphorylation of human Bora by Cdk1 promotes phosphorylation of human Plk1 by Aurora A, suggesting that this mechanism is conserved in humans. Our results suggest that CDK-1 activates PLK-1 via SPAT-1 phosphorylation to promote entry into mitosis. We propose the existence of a positive feedback loop that connects Cdk1 and Plk1 activation to ensure a robust control of mitotic entry and cell division timing.
在动物发育过程中，调控有丝分裂进入的分子机制尚未完全明确。在此，我们发现有丝分裂激酶CDK - 1磷酸化Par - Two抑制因子1（SPAT - 1）/Bora，以调节其与PLK - 1的相互作用，并在秀丽隐杆线虫早期胚胎中触发有丝分裂进入。表达一种不能被CDK - 1磷酸化且在体外与PLK - 1结合存在缺陷的SPAT - 1变体的胚胎，在有丝分裂进入时出现延迟，类似于缺乏SPAT - 1或PLK - 1功能的胚胎。我们进一步表明，磷酸化的SPAT - 1通过在体外触发极光激酶A对其激活剂T环的磷酸化来激活PLK - 1。同样，我们发现Cdk1对人Bora的磷酸化促进了极光激酶A对人Plk1的磷酸化，这表明该机制在人类中是保守的。我们的结果表明，CDK - 1通过SPAT - 1磷酸化激活PLK - 1，以促进进入有丝分裂。我们提出存在一个正反馈回路，将Cdk1和Plk1的激活联系起来，以确保对有丝分裂进入和细胞分裂时间进行强有力的控制。
