Microtubule-mediated transport of the tumor-suppressor protein Merlin and its mutants
Microtubule-mediated transport of the tumor-suppressor protein Merlin and its mutants
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DOI：
10.1073/pnas.0907389107
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发表时间：
2010-04-20
影响因子：
11.1
通讯作者：
Gelfand, Vladimir I.
中科院分区：
文献类型：
--
作者：
Bensenor, Lorena B.;Barlan, Kari;Gelfand, Vladimir I.
2 型神经纤维瘤病 (NF2) 肿瘤抑制蛋白 Merlin 是 ERM 蛋白家族的成员，该蛋白将细胞骨架与质膜连接起来。在人类中，NF2 基因突变会导致 2 型神经纤维瘤病 (NF2)，这是一种以神经系统肿瘤发展为特征的癌症综合征。先前的报告表明，Merlin 的亚细胞分布对其功能至关重要，并且一些缺乏肿瘤抑制活性的 NF2 突变体存在不正确的定位。在这里，我们使用果蝇细胞培养模型来研究Merlin及其突变体的细胞内运输分布和机制。我们发现果蝇 Merlin 形成沿着微管双向移动的细胞质颗粒。 FERM 结构域中单个引起 NF2 的氨基酸取代显着抑制了 Merlin 颗粒的运动。令人惊讶的是，这种不动的 Merlin 突变体的存在也抑制了 WT 蛋白的运输。使用 RNAi 和 Pull-downs 对 WT 蛋白的运动进行分析表明，Merlin 颗粒与微管马达（驱动蛋白-1 和细胞质动力蛋白）相关并由其移动，并且马达和运动的结合受 Merlin 磷酸化的调节。通过显性失活突变体的表达或驱动蛋白-1 的消耗来抑制 Merlin 转运会导致转录共激活因子 Yorkie 的核积累增加。这些结果证明了 Merlin 功能需要微管依赖性运输。
The neurofibromatosis type 2 (NF2) tumor-suppressor protein Merlin is a member of the ERM family of proteins that links the cytoskeleton to the plasma membrane. In humans, mutations in the NF2 gene cause neurofibromatosis type-2 (NF2), a cancer syndrome characterized by the development of tumors of the nervous system. Previous reports have suggested that the subcellular distribution of Merlin is critical to its function, and that several NF2 mutants that lack tumor-suppressor activity present improper localization. Here we used a Drosophila cell culture model to study the distribution and mechanism of intracellular transport of Merlin and its mutants. We found that Drosophila Merlin formed cytoplasmic particles that move bidirectionally along micro-tubules. A single NF2-causing amino acid substitution in the FERM domain dramatically inhibited Merlin particle movement. Surprisingly, the presence of this immotile Merlin mutant also inhibited trafficking of the WT protein. Analysis of the movement of WT protein using RNAi and pull-downs showed that Merlin particles are associated with and moved by microtubule motors (kinesin-1 and cytoplasmic dynein), and that binding of motors and movement is regulated by Merlin phosphorylation. Inhibition of Merlin transport by expression of the dominant-negative mutant or depletion of kinesin-1 results in increased nuclear accumulation of the transcriptional coactivator Yorkie. These results demonstrate the requirement of microtubule-dependent transport for Merlin function.