Hook2 is involved in the morphogenesis of the primary cilium.
Hook2 is involved in the morphogenesis of the primary cilium.
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DOI：
10.1091/mbc.e11-05-0405
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发表时间：
2011-12
影响因子：
3.3
通讯作者：
Le Bivic A
中科院分区：
文献类型：
--
作者：
Baron Gaillard CL;Pallesi-Pocachard E;Massey-Harroche D;Richard F;Arsanto JP;Chauvin JP;Lecine P;Krämer H;Borg JP;Le Bivic A
Hook2分隔在高尔基体和中心体之间，它的缺失阻碍了母中心粒成熟后没有高尔基分解的纤毛发生。Hook2与PCM1和Rab8a相互作用，通过过表达GFP::Rab8a，使Hook2缺失的细胞被迫生长原毛，表明Rab8a作用于Hook2和PCM1的下游。初级纤毛起源于中心体，在许多细胞、发育和病理过程中发挥重要作用，但纤毛发生的潜在机制尚不完全清楚。考虑到衔接蛋白Hook2参与中心体稳态和蛋白转运到中心体周围聚合体，我们探讨了它在纤毛发生中的作用。我们发现，在人视网膜上皮细胞中，Hook2定位于高尔基体和中心体/基底体，这是纤毛发生的战略分配。重要的是，Hook2缺失在母体中心粒远端纤毛囊形成之前的一个阶段破坏了纤毛的发生。通过两种杂交和免疫沉淀试验以及小干扰RNA策略，我们发现Hook2与中心周围物质蛋白1 （PCM1）相互作用并稳定PCM1，据报道，PCM1对于Rab8a的募集至关重要，Rab8a是一种GTPase，被认为是细胞膜运输到初级毛毛的关键。有趣的是，GFP::Rab8a与内源性Hook2和PCM1共免疫沉淀。最后，GFP::Rab8a可以克服Hook2的缺失，表明Hook2与这两个重要的纤毛发生调节因子之间存在功能相互作用。数据表明，Hook2在一个包含Rab8a的复合体中与PCM1相互作用，并调节中心粒成熟后进一步启动纤毛发生所需的限制步骤。
Hook2 partitions between the Golgi apparatus and the centrosome, and its depletion hinders ciliogenesis after mother centriole maturation without Golgi breakdown. Hook2 interacts with PCM1 and Rab8a, and Hook2-depleted cells can be forced to grow primary cilia by overexpressing GFP::Rab8a, indicating that Rab8a acts downstream of Hook2 and PCM1. Primary cilia originate from the centrosome and play essential roles in several cellular, developmental, and pathological processes, but the underlying mechanisms of ciliogenesis are not fully understood. Given the involvement of the adaptor protein Hook2 in centrosomal homeostasis and protein transport to pericentrosomal aggresomes, we explored its role in ciliogenesis. We found that in human retinal epithelial cells, Hook2 localizes at the Golgi apparatus and centrosome/basal body, a strategic partitioning for ciliogenesis. Of importance, Hook2 depletion disrupts ciliogenesis at a stage before the formation of the ciliary vesicle at the distal tip of the mother centriole. Using two hybrid and immunoprecipitation assays and a small interfering RNA strategy, we found that Hook2 interacts with and stabilizes pericentriolar material protein 1 (PCM1), which was reported to be essential for the recruitment of Rab8a, a GTPase that is believed to be crucial for membrane transport to the primary cilium. Of interest, GFP::Rab8a coimmunoprecipitates with endogenous Hook2 and PCM1. Finally, GFP::Rab8a can overcome Hook2 depletion, demonstrating a functional interaction between Hook2 and these two important regulators of ciliogenesis. The data indicate that Hook2 interacts with PCM1 in a complex that also contains Rab8a and regulates a limiting step required for further initiation of ciliogenesis after centriole maturation.