Chen Feng, Archambault Vincent, Kar Ashok, Lio' Pietro, D'Avino Pier Paolo, Sinka Rita, Lilley Kathryn, Laue Ernest D, Deak Peter, Capalbo Luisa, Glover David M
Cancer Research United Kingdom, Cell Cycle Genetics Research Group, Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, United Kingdom.
Curr Biol. 2007 Feb 20;17(4):293-303. doi: 10.1016/j.cub.2007.01.068.
Approximately one-third of the Drosophila kinome has been ascribed some cell-cycle function. However, little is known about which of its 117 protein phosphatases (PPs) or subunits have counteracting roles.
We investigated mitotic roles of PPs through systematic RNAi. We found that G(2)-M progression requires Puckered, the JNK MAP-kinase inhibitory phosphatase and PP2C in addition to string (Cdc25). Strong mitotic arrest and chromosome congression failure occurred after Pp1-87B downregulation. Chromosome alignment and segregation defects also occurred after knockdown of PP1-Flapwing, not previously thought to have a mitotic role. Reduction of several nonreceptor tyrosine phosphatases produced spindle and chromosome behavior defects, and for corkscrew, premature chromatid separation. RNAi of the dual-specificity phosphatase, Myotubularin, or the related Sbf "antiphosphatase" resulted in aberrant mitotic chromosome behavior. Finally, for PP2A, knockdown of the catalytic or A subunits led to bipolar monoastral spindles, knockdown of the Twins B subunit led to bridged and lagging chromosomes, and knockdown of the B' Widerborst subunit led to scattering of all mitotic chromosomes. Widerborst was associated with MEI-S332 (Shugoshin) and required for its kinetochore localization.
We identify cell-cycle roles for 22 of 117 Drosophila PPs. Involvement of several PPs in G(2) suggests multiple points for its regulation. Major mitotic roles are played by PP1 with tyrosine PPs and Myotubularin-related PPs having significant roles in regulating chromosome behavior. Finally, depending upon its regulatory subunits, PP2A regulates spindle bipolarity, kinetochore function, and progression into anaphase. Discovery of several novel cell-cycle PPs identifies a need for further studies of protein dephosphorylation.
果蝇激酶组中约三分之一已被赋予某些细胞周期功能。然而，对于其117种蛋白磷酸酶（PPs）或亚基中哪些具有拮抗作用，人们了解甚少。
我们通过系统性RNA干扰研究了PPs的有丝分裂作用。我们发现，除了String（Cdc25）之外，G2期到M期的进程还需要褶皱蛋白（Puckered）、JNK丝裂原活化蛋白激酶抑制性磷酸酶和PP2C。下调Pp1 - 87B后出现强烈的有丝分裂停滞和染色体排列失败。敲低之前认为没有有丝分裂作用的PP1 - 襟翼翅蛋白（Flapwing）后也出现了染色体排列和分离缺陷。几种非受体酪氨酸磷酸酶的减少导致纺锤体和染色体行为缺陷，而对于螺旋蛋白（corkscrew），则导致染色单体过早分离。双特异性磷酸酶肌管蛋白（Myotubularin）或相关的Sbf“抗磷酸酶”的RNA干扰导致有丝分裂染色体行为异常。最后，对于PP2A，催化亚基或A亚基的敲低导致双极单星体纺锤体，Twins B亚基的敲低导致染色体桥接和滞后，B'宽体（Widerborst）亚基的敲低导致所有有丝分裂染色体分散。宽体与MEI - S332（守护蛋白）相关联，并且是其在动粒定位所必需的。
我们确定了果蝇117种PPs中的22种在细胞周期中的作用。几种PPs参与G2期表明其调控存在多个点。PP1在有丝分裂中起主要作用，酪氨酸PPs和与肌管蛋白相关的PPs在调节染色体行为中具有重要作用。最后，根据其调节亚基的不同，PP2A调节纺锤体双极性、动粒功能以及进入后期的进程。几种新型细胞周期PPs的发现表明需要对蛋白质去磷酸化进行进一步研究。
