2015年12月16日，国际顶级期刊《The Plant Cell》在线刊登复旦大学马红教授研究团队题为“Arabidopsis cell division Cycle 20.1 Is Required for Normal Meiotic Spindle Assembly and Chromosome Segregation”最新研究论文。研究首次揭示了细胞分裂周期蛋白CDC20.1通过参与纺锤体组装检验点(Spindle Assembly Checkpoint，SAC)依赖的途径而影响减数分裂过程中同源染色体的正确分离。
细胞分裂是生物体生长、发育、繁殖和遗传的生命活动基础，包括有丝分裂和减数分裂。减数分裂中同源染色体和姊妹染色单体的两次正确分离，保证了遗传信息正确分配到子细胞(精子和卵子)中。错误的染色体分离会影响精子或卵子的质量，进而影响生殖健康。据研究统计，不育不孕和出生缺陷与染色体异常分离相关。目前，染色体分离的分子机制研究主要集中在有丝分裂，减数分裂过程中，尤其是第一次同源染色体之间的分离研究还不多。同源染色体在后期分离之前，需要纺锤体与动粒的正确结合。染色体在纺锤体动力的牵拉下并列排列在赤道板上，当染色单体臂上的粘黏蛋白被降解后，同源染色体被精确的分向两极。已有研究表明，纺锤体与动粒的结合极性有对有错，这些错误的结合必需在适当的时候被纠正，否则会影响染色体在赤道板上的正确排列。但目前仍不清楚相关的调节机制是否直接影响减数分裂中染色体的分离。
Cell Division Cycle 20(CDC20)是真核生物中高度保守的蛋白，作为细胞分裂后期促进复合物(Anphase Promoting Complex, APC)的激活因子，通过泛素化降解影响细胞周期和染色体粘黏蛋白，从而影响染色体的分离。本研究表明，模式植物拟南芥有5个CDC20基因，其中CDC20.1和CDC20.2是在十字花科内近期产生的一对串联重复(图1)，CDC20.3/4/5则可能是假基因。在有丝分裂中，CDC20.1和CDC20.2是必需的，且二者存在功能冗余;而减数分裂则只需要CDC20.1。
对CDC20.1的功能研究发现，由于纺锤体与动粒的错误结合没有得到纠正，突变体的同源染色体在减数分裂中期I不能正确排列在赤道板上。进一步的研究表明：导致这种异常排列的分子机制是CDC20.1直接或间接地影响了组蛋白的磷酸化，从而调控染色体的正确排列和后期的精确分离(图2)。综上，CDC20.1通过参与纺锤体组装检验点依赖的途径而影响减数分裂过程中同源染色体的分离。
原文链接：
Arabidopsis Cell Division Cycle 20.1 Is Required for Normal Meiotic Spindle Assembly and Chromosome Segregation
原文摘要：
Cell division requires proper spindle assembly; a surveillance pathway, the spindle assembly checkpoint (SAC), monitors whether the spindle is normal and correctly attached to kinetochores. The SAC proteins regulate mitotic chromosome segregation by affecting CDC20 (Cell Division Cycle 20) function. However, it is unclear whether CDC20 regulates meiotic spindle assembly and proper homolog segregation. Here, we show that the Arabidopsis thalianaCDC20.1 gene is indispensable for meiosis and male fertility. We demonstrate that cdc20.1 meiotic chromosomes align asynchronously and segregate unequally and the metaphase I spindle has aberrant morphology. Comparison of the distribution of meiotic stages at different time points between the wild type andcdc20.1 reveals a delay of meiotic progression from diakinesis to anaphase I. Furthermore, cdc20.1 meiocytes exhibit an abnormal distribution of a histone H3 phosphorylation mark mediated by the Aurora kinase, providing evidence that CDC20.1 regulates Aurora localization for meiotic chromosome segregation. Further evidence that CDC20.1 and Aurora are functionally related was provided by meiosis-specific knockdown of At-Aurora1 expression, resulting in meiotic chromosome segregation defects similar to those of cdc20.1. Taken together, these results suggest a critical role for CDC20.1 in SAC-dependent meiotic chromosome segregation.
（责任编辑：fangqi）
