染色体数目的非整倍性是癌细胞的重要特征和癌变的潜在诱因，主要由有丝分裂期染色体的异常分离所致。姐妹染色体之间的粘连是染色体精确分离的根本前提。染色体粘连疲劳，即有丝分裂中期滞留导致染色体非同步化错误分离的现象，是近几年报道的染色体粘连缺陷的新形式，受到同行关注。基于染色体粘连疲劳对基因组稳定性的威胁，一系列相关重要问题亟待解决。本课题拟利用小分子抑制剂、RNA干扰、CRISPR-Cas9基因组编辑、超高分辨率显微镜和活细胞实时成像等关键技术，调查染色体粘连疲劳的普遍性和严重程度，描述粘连疲劳造成染色体异常分离的特点，探讨粘连疲劳的成因与后果。基于Haspin基因突变严重加剧染色体粘连疲劳的预实验结果，我们推测并将验证Haspin以不依赖于其蛋白激酶活性的方式促进染色体粘连的分子机制。课题的顺利完成将揭示染色体粘连调控的新机制，丰富有丝分裂研究的基础理论，并为相关抗癌药物的研发提供新的依据。

Numerical, whole-chromosome aneuploidy is a common characteristics of tumors and has been proposed to drive tumor progression. Aneuploidy is often caused by errors in chromosome segregation during mitosis. Sister chromatid cohesion is an essential prerequisite for faithful chromosome segregation, defects in which lead to chromosome missegregation and the subsequent production of aneuploid daughter cells. Recent studies showed that cells arrested or delayed at metaphase undergo asynchronous and unscheduled separation of sister chromatids. This phenomenon is termed cohesion fatigue which constitutes a previously overlooked type of cohesion defects. Given its conceivable contribution to chromosome instability, a lot of important questions associated with cohesion fatigue remain to be addressed. Here, we aim to investigate how frequently cohesion fatigue occurs at least in certain types of cancer cells, as well as the causes and potential consequences of cohesion fatigue. Importantly, we found severe chromosome cohesion fatigue in our preliminary studies of targeted genome engineering by CRISPR-Cas9 in the gene encoding the serine/threonine kinase Haspin, which has been implicated in chromosome cohesion regulation with unknown mechanism. We hypothesize that Haspin plays a key role in preventing chromosome cohesion fatigue in a way independent of its kinase activity. Combining co-immunoaffinity purification and identification of Haspin-interacting proteins involved in cohesion regulation with functional studies of separation-of-function mutants, we aim to dissect the molecular mechanism by which Haspin functions directly in promoting chromosome cohesion. These studies will be carried out by emerging techniques including small molecule inhibitors, RNAi complementation, genome engineering with CRISPR-Cas9, super-resolution imaging and time-lapse microscopy of live cells. Upon successful conclusion of these studies, we will have revealed the mechanisms associated with chromosome cohesion fatigue, and have provided novel insights into the sophisticated regulation of mitosis which is also important for the development of new anti-mitotic cancer therapeutics.