Centrin deficiency in Chlamydomonas causes defects in basal body replication, segregation and maturation
Centrin deficiency in Chlamydomonas causes defects in basal body replication, segregation and maturation
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DOI：
10.1242/jcs.00497
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发表时间：
2003-07-01
影响因子：
4
通讯作者：
Lechtreck, KF
中科院分区：
文献类型：
--
作者：
Koblenz, B;Schoppmeier, J;Lechtreck, KF
中心蛋白是一种分子量为20 kDa的钙结合蛋白，是原生生物收缩性基体相关纤维和各种中心体结构的组成部分。使用诱导中心蛋白RNAi的构建体来研究中心蛋白缺乏对衣原体的影响。转化体含有可变量的残留中心蛋白（下降到野生型的5%），缺乏中心蛋白纤维。他们表现出一个可变的鞭毛数量的表型与大多数nonflagellate细胞，表明centrin是所需的基体大会。此外，基体往往无法对接到质膜和组装鞭毛，并显示缺陷的鞭毛根系统表明，中心蛋白缺乏干扰基体的发展。多个基体导致形成额外的微管星状体，而在大多数细胞中，没有基体的微管细胞骨架紊乱。多核细胞数量增加，表明异常的基体数量干扰了衣藻的胞质分裂。与野生型细胞相反，centrin-RNAi细胞中的基底体与纺锤体极分离，表明centrin在将基底体拴系到纺锤体中的作用。为了测试是否与纺锤体两极的关联是正确的基体分离所必需的，我们通过过表达非功能性中心蛋白-GFP来破坏野生型细胞中的中心蛋白纤维。在这些细胞中，基体从纺锤体断开，但没有观察到分离错误。我们建议，在衣原体的基体隔离依赖于一个独立的有丝分裂纺锤体微管的双核阵列。
Centrin, a 20 kDa calcium-binding protein, is a constituent of contractile basal body-associated fibers in protists and of various centrosomal structures. A construct inducing centrin RNAi was used to study the effect of centrin deficiency in Chlamydomonas. Transformants contained variable amounts of residual centrin (down to 5% of wildtype) and lacked centrin fibers. They displayed a variable flagellar number phenotype with mostly nonflagellate cells, suggesting that centrin is required for basal body assembly. Furthermore, basal bodies often failed to dock to the plasma membrane and to assemble flagella, and displayed defects in the flagellar root system indicating that centrin deficiency interferes with basal body development. Multiple basal bodies caused the formation of additional microtubular asters, whereas the microtubular cytoskeleton was disordered in most cells without basal bodies. The number of multinucleated cells was increased, indicating that aberrant numbers of basal bodies interfered with the cytokinesis of Chlamydomonas. In contrast to wildtype cells, basal bodies in centrin-RNAi cells were separated from the spindle poles, suggesting a role of centrin in tethering basal bodies to the spindle. To test whether an association with the spindle poles is required for correct basal body segregation, we disrupted centrin fibers in wild-type cells by over-expressing a nonfunctional centrin-GFP. In these cells, basal bodies were disconnected from the spindle but segregation errors were not observed. We propose that basal body segregation in Chlamydomonas depends on an extranuclear array of microtubules independent of the mitotic spindle.