Activation of m-calpain is required for chromosome alignment on the metaphase plate during mitosis
Activation of m-calpain is required for chromosome alignment on the metaphase plate during mitosis
复制标题
DOI：
10.1074/jbc.m308841200
复制
发表时间：
2004-03-12
影响因子：
4.8
通讯作者：
Saya, H
中科院分区：
文献类型：
--
作者：
Honda, S;Marumoto, T;Saya, H
钙蛋白酶形成Ca2+依赖性细胞内半胱氨酸蛋白酶的超家族，具有不同的亚型。两种同工异构体，mu-和m-calpain，被普遍表达，被称为常规calpain。先前已经表明，哺乳动物钙蛋白酶在有丝分裂期间通过胞质Ca2+浓度的短暂增加而被激活。然而，calpain的激活是否对有丝分裂中的特定事件有贡献尚不清楚。利用RNA干扰（RNAi）技术，我们研究了钙蛋白酶在有丝分裂中的作用。细胞减少了m- calpain的水平，但没有减少mu-calpain的水平，在纺锤体赤道处染色体不能排列。特异性肽基钙蛋白酶抑制剂也可诱导染色体错位的异常有丝分裂。尽管m- calpain RNAi和calpain抑制剂既不影响中心体的分离，也不影响双极纺锤体的组装，但在错配染色体的着丝点上检测到Mad2，这表明calpain抑制引起的前期停滞是由于纺锤体组装检查点的激活。此外，在单极纺锤体细胞中，当钙蛋白酶活性被抑制时，染色体聚集在中心体附近，这表明钙蛋白酶活性参与了染色体中期排列的极性抛射力。基于这些发现，我们提出细胞在有丝分裂过程中激活m-钙蛋白酶是通过调节一些产生极性喷射力的分子来建立染色体排列所必需的。
Calpains form a superfamily of Ca2+-dependent intracellular cysteine proteases with various isoforms. Two isoforms, mu- and m-calpains, are ubiquitously expressed and known as conventional calpains. It has been previously shown that the mammalian calpains are activated during mitosis by transient increases in cytosolic Ca2+ concentration. However, it is still unknown whether the activation of calpains contributes to particular events in mitosis. With the use of RNA interference (RNAi), we investigated the roles of calpains in mitosis. Cells reduced the levels of m- calpain, but not mu-calpain, arrested at prometaphase and failed to align their chromosomes at the spindle equator. Specific peptidyl calpain inhibitors also induced aberrant mitosis with chromosome misalignment. Although both m- calpain RNAi and calpain inhibitors affected neither the separation of centrosomes nor the assembly of bipolar spindles, Mad2 was detected on the kinetochores of the misaligned chromosomes, indicating that the prometaphase arrest induced by calpain inhibition is due to activation of the spindle assembly checkpoint. Furthermore, when calpain activity was inhibited in cells having monopolar spindles, chromosomes were clustered adjacent to the centrosome, suggesting that calpain activity is involved in a polar ejection force for metaphase alignment of chromosomes. Based on these findings, we propose that activation of m- calpain during mitosis is required for cells to establish the chromosome alignment by regulating some molecules that generate polar ejection force.