Identification and activity of new regulators of cell division.

蛋白激酶Cdk1与其激活因子细胞周期蛋白B复合物，是有丝分裂的主要调控因子。在最近的筛选中（Hegarat et al. 2018），我们鉴定了125个Cyclin B/Cdk1的特异性底物。其中包括控制重要有丝分裂途径的因子，如染色体客运复合体（又名Aurora B复合体）、Ki67和着丝点组装组分。在先前未确定的底物中发现已知的Cdk1靶点，使我们确信我们的方法是有效的。由于大多数细胞周期蛋白B依赖的Cdk1磷酸化确实对有丝分裂进程至关重要，我们假设在该筛选中鉴定的新蛋白具有必要的有丝分裂功能。我们将通过siRNA缺失和细胞周期蛋白B/Cdk1底物的有丝分裂表型分析来测试这一点。我们将研究基于rnai的8个未知功能的未表征靶标耗竭的影响。此外，我们将分析参与“细胞周期调节”的三种蛋白质，四种“着丝粒组织”调节因子，两种“核层”成分和两种“蛋白质磷酸酶”，以及选择相当意外地确定的靶标：“肌动蛋白组织”网络的三个成员，“内质网组织”的两个蛋白质和“核糖体生物发生”组的两个蛋白质。从这26个不同的目标中，我们将选择最有希望和最有趣的候选人进行进一步研究。实际上，学生将能够剖析多达三种新的有丝分裂调节因子的作用，这将导致识别控制有丝分裂的新调节机制。从战略的角度来看，这将是一个真正的、真正的合作努力，它将我们的研究单位聚集在一起，并允许积累令人兴奋的、高质量的数据，这些数据将用于准备提交给BBSRC或MRC的项目资助申请。

Protein kinase Cdk1, complexed with its activator Cyclin B, is a master-regulator of mitosis. In a recent screen (Hegarat et al. 2018), we identified 125 specific substrates of Cyclin B/Cdk1. Among them were factors controlling essential mitotic pathways, such as Chromosome Passenger Complex (aka Aurora B complex), Ki67, and kinetochore assembly components. Findings of known Cdk1 targets among the previously unidentified substrates assured us about the validity of our approach. Since most of the Cyclin B dependent phosphorylations by Cdk1 indeed are critically important for mitotic progression, we hypothesised that the novel proteins identified in this screen have essential mitotic functions. We will test this by the siRNA depletion and mitotic phenotype analysis of the panel of Cyclin B/Cdk1 substrates. We will study the effects of the RNAi-based depletion of eight uncharacterised targets of an unknown function. Additionally we will analyse three proteins involved in the "cell cycle regulation", four "kinetochore organisation" regulators, two "nuclear lamina" components, and two "protein phosphatases", as well as the selection of rather unexpectedly identified targets: three members if the "actin organisation" network, two proteins involved in the "endoplasmic reticulum organisation" and two from the "ribosome biogenesis" group. From among those 26 different targets, we will chose the most promising and interesting candidates to be studied further. Realistically, the student will be able to dissect the role of up to three new mitotic regulators, which will lead to the identification of new regulatory mechanisms that control mitosis. From the strategical point of view, it will be a genuine, real collaborative effort, which brings our research units together and allows for the accumulation of exciting, top quality data that will be used for preparing an application for a project grant (or grants) submitted to BBSRC or MRC.