Avena Jennifer S, Burns Shannon, Yu Zulin, Ebmeier Christopher C, Old William M, Jaspersen Sue L, Winey Mark
Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America.
Stowers Institute for Medical Research, Kansas City, Missouri, United States of America.
PLoS Genet. 2014 Oct 23;10(10):e1004666. doi: 10.1371/journal.pgen.1004666. eCollection 2014 Oct.
Duplication of centrosomes once per cell cycle is essential for bipolar spindle formation and genome maintenance and is controlled in part by cyclin-dependent kinases (Cdks). Our study identifies Sfi1, a conserved component of centrosomes, as the first Cdk substrate required to restrict centrosome duplication to once per cell cycle. We found that reducing Cdk1 phosphorylation by changing Sfi1 phosphorylation sites to nonphosphorylatable residues leads to defects in separation of duplicated spindle pole bodies (SPBs, yeast centrosomes) and to inappropriate SPB reduplication during mitosis. These cells also display defects in bipolar spindle assembly, chromosome segregation, and growth. Our findings lead to a model whereby phosphoregulation of Sfi1 by Cdk1 has the dual function of promoting SPB separation for spindle formation and preventing premature SPB duplication. In addition, we provide evidence that the protein phosphatase Cdc14 has the converse role of activating licensing, likely via dephosphorylation of Sfi1.
每个细胞周期中心体复制一次对于双极纺锤体形成和基因组维持至关重要，并且部分受细胞周期蛋白依赖性激酶（Cdks）调控。我们的研究确定了中心体的一个保守成分Sfi1，它是将中心体复制限制在每个细胞周期一次所需的首个Cdk底物。我们发现，通过将Sfi1磷酸化位点变为不可磷酸化残基来降低Cdk1磷酸化，会导致复制的纺锤体极体（SPB，酵母中心体）分离缺陷，并在有丝分裂期间导致不适当的SPB重新复制。这些细胞在双极纺锤体组装、染色体分离和生长方面也表现出缺陷。我们的发现得出了一个模型，即Cdk1对Sfi1的磷酸化调节具有促进纺锤体形成的SPB分离和防止SPB过早复制的双重功能。此外，我们提供证据表明，蛋白磷酸酶Cdc14可能通过使Sfi1去磷酸化而具有激活许可的相反作用。
