Huntingtin coordinates the dynein-mediated dynamic positioning of endosomes and lysosomes.
Huntingtin coordinates the dynein-mediated dynamic positioning of endosomes and lysosomes.
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DOI：
10.1091/mbc.e10-03-0233
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发表时间：
2011-02-15
影响因子：
3.3
通讯作者：
Holzbaur EL
中科院分区：
文献类型：
--
作者：
Caviston JP;Zajac AL;Tokito M;Holzbaur EL
我们研究了膜相关支架蛋白亨廷顿蛋白（Htt）在动力蛋白介导的早期、再循环和晚期内体和溶酶体运输中的作用。我们的观察结果支持Htt作为动力蛋白介导的运输促进者的模型，可以调节动态细胞器的细胞骨架关联。亨廷顿蛋白（Htt）是一种膜相关支架蛋白，可与微管马达以及肌动蛋白相关接头分子相互作用。我们研究了Htt在动力蛋白介导的内体和溶酶体的细胞内运输中的作用。在缺乏Htt或动力蛋白的HeLa细胞中，早期、再循环和晚期核内体/溶酶体都变得分散。尽管改变了细胞器定位，动力学分析表明细胞内运输只有轻微缺陷。全长Htt的表达是恢复Htt缺失细胞的细胞器定位所必需的，这支持了Htt作为促进沿其长度的功能相互作用的支架的作用。在动力蛋白耗竭的细胞中，LE/溶酶体聚集在皮层附近的紧密斑块中，显然被接触蛋白阳性的肌动蛋白丝缠绕；拉曲库林b治疗可分散这些斑块。动力蛋白耗竭细胞中的外周LE/溶酶体不再与微管共定位。这种卸载可能需要Htt，因为在Htt耗尽的细胞或同时耗尽动力蛋白和Htt的细胞中未见微管关联的丧失。Htt耗竭而不是动力蛋白耗竭诱导的外周LE/溶酶体对激酶1的抑制使其重新定位，这与动力蛋白被抑制后它们从微管中脱离是一致的。总之，这些数据支持Htt作为动力蛋白介导的运输促进者的模型，可能调节动态细胞器的细胞骨架关联。
We investigated the role of the membrane-associated scaffolding protein huntingtin (Htt) in the dynein-mediated transport of early, recycling, and late endosomes and lysosomes. Our observations support a model of Htt as a facilitator of dynein-mediated trafficking that can regulate the cytoskeletal association of dynamic organelles. Huntingtin (Htt) is a membrane-associated scaffolding protein that interacts with microtubule motors as well as actin-associated adaptor molecules. We examined a role for Htt in the dynein-mediated intracellular trafficking of endosomes and lysosomes. In HeLa cells depleted of either Htt or dynein, early, recycling, and late endosomes (LE)/lysosomes all become dispersed. Despite altered organelle localization, kinetic assays indicate only minor defects in intracellular trafficking. Expression of full-length Htt is required to restore organelle localization in Htt-depleted cells, supporting a role for Htt as a scaffold that promotes functional interactions along its length. In dynein-depleted cells, LE/lysosomes accumulate in tight patches near the cortex, apparently enmeshed by cortactin-positive actin filaments; Latrunculin B-treatment disperses these patches. Peripheral LE/lysosomes in dynein-depleted cells no longer colocalize with microtubules. Htt may be required for this off-loading, as the loss of microtubule association is not seen in Htt-depleted cells or in cells depleted of both dynein and Htt. Inhibition of kinesin-1 relocalizes peripheral LE/lysosomes induced by Htt depletion but not by dynein depletion, consistent with their detachment from microtubules upon dynein knockdown. Together, these data support a model of Htt as a facilitator of dynein-mediated trafficking that may regulate the cytoskeletal association of dynamic organelles.