Gene knockouts reveal separate functions for two cytoplasmic dyneins in Tetrahymena thermophila
Gene knockouts reveal separate functions for two cytoplasmic dyneins in Tetrahymena thermophila
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DOI：
10.1091/mbc.10.3.771
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发表时间：
1999-03-01
影响因子：
3.3
通讯作者：
Asai, DJ
中科院分区：
文献类型：
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作者：
Lee, S;Wisniewski, JC;Asai, DJ
在许多生物体中，细胞质动力蛋白重链存在多种异构体，异构体之间的分工将为调节动力蛋白功能提供一种机制。嗜热四膜虫体细胞基因的定向破坏为确定在一个表达多种动力蛋白重链基因的单细胞中单个动力蛋白异构体的作用提供了机会。克隆了两个嗜热四膜虫细胞质动力蛋白重链基因的大部分片段，并对其运动结构域进行了测序。嗜热四膜虫DYH1编码普遍存在的细胞质动力蛋白Dyh1，DYH2编码第二种细胞质动力蛋白异构体Dyh2。DYH1（而非DYH2）的破坏导致细胞出现两种可检测到的缺陷：1）吞噬活性受到抑制；2）细胞在小核有丝分裂过程中无法正确分配染色体。相比之下，DYH2的破坏导致细胞大小和形状的调控丧失，以及细胞显然无法修复其皮质细胞骨架。我们得出结论，在嗜热四膜虫中这两种动力蛋白执行不同的任务。
In many organisms, there are multiple isoforms of cytoplasmic dynein heavy chains, and division of labor among the isoforms would provide a mechanism to regulate dynein function. The targeted disruption of somatic genes in Tetrahymena thermophila presents the opportunity to determine the contributions of individual dynein isoforms in a single cell that expresses multiple dynein heavy chain genes. Substantial portions of two Tetrahymena cytoplasmic dynein heavy chain genes were cloned, and their motor domains were sequenced. Tetrahymena DYH1 encodes the ubiquitous cytoplasmic dynein Dyh1, and DYH2 encodes a second cytoplasmic dynein isoform, Dyh2. The disruption of DYH1, but not DYH2, resulted in cells with two detectable defects: 1) phagocytic activity was inhibited, and 2) the cells failed to distribute their chromosomes correctly during micronuclear mitosis. In contrast, the disruption of DYH2 resulted in a loss of regulation of cell size and cell shape and in the apparent inability of the cells to repair their cortical cytoskeletons. We conclude that the two dyneins perform separate tasks in Tetrahymena.