MKS5 and CEP290 Dependent Assembly Pathway of the Ciliary Transition Zone.
MKS5 and CEP290 Dependent Assembly Pathway of the Ciliary Transition Zone.
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DOI：
10.1371/journal.pbio.1002416
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发表时间：
2016-03
期刊：
影响因子：
9.8
通讯作者：
Leroux MR
中科院分区：
文献类型：
--
作者：
Li C;Jensen VL;Park K;Kennedy J;Garcia-Gonzalo FR;Romani M;De Mori R;Bruel AL;Gaillard D;Doray B;Lopez E;Rivière JB;Faivre L;Thauvin-Robinet C;Reiter JF;Blacque OE;Valente EM;Leroux MR
纤毛在其近端区域有一个独特的扩散屏障（“门”），称为过渡区（TZ），它将细胞器内的信号蛋白区分开来。已知 TZ 包含两个功能模块/复合体（梅克尔综合征 [MKS] 和肾痨 [NPHP]），由遗传相互作用、相互依赖的蛋白质定位（层次结构）和蛋白质组学研究定义。然而，这些模块的组成和分子组织及其与人类睫状体疾病的联系尚不完全清楚。在这里，我们揭示了秀丽隐杆线虫 CEP-290（哺乳动物 Cep290/Mks4/Nphp6 直系同源物）作为中心组装因子，该因子特定于已建立的 MKS 模块组件，并且依赖于 MKS-5 (Rpgrip1L/Rpgrip1) 的卷曲线圈区域进行 TZ 定位。与纤毛门功能中的关键作用一致，CEP-290 可防止膜相关蛋白不适当地进入纤毛，并防止 ARL-13 (Arl13b) 通过 TZ 渗漏出纤毛。我们确定了一种新颖的 MKS 模块组件 TMEM-218 (Tmem218)，它需要 CEP-290 和其他 MKS 模块组件来进行 TZ 本地化，并与 NPHP 模块一起发挥作用以促进纤毛发生。我们表明，TMEM-138 (Tmem138) 和 CDKL-1（Cdkl1/Cdkl2/Cdkl3/Cdlk4 相关）的 TZ 本地化，之前未链接到特定的 TZ 模块，同样依赖于 CEP-290；令人惊讶的是，TMEM-138 或 CDKL-1 均未表现出与核心 MKS 或 NPHP 模块组件相互依赖的定位或遗传相互作用，这表明它们是独特的 CEP-290 相关模块的一部分。最后，我们发现患有 6 型口面部数字综合征 (OFD6) 的家庭可能在 CEP-290 依赖性 TZ 蛋白（即 Tmem17、Tmem138 和 Tmem231）中存在致病性突变。值得注意的是，携带突变 Tmem17（一种尚未与纤毛病相关的蛋白质）的患者成纤维细胞表现出纤毛发生缺陷。总之，我们的研究结果扩展了 MKS 模块相关蛋白的库（包括以前未表征的哺乳动物 Tmem80），并提出了构建功能性 TZ 的依赖于 MKS-5 和 CEP-290 的组装途径。过渡区是维持纤毛动态组成和功能完整性所需的屏障结构。这项研究描述了纤毛形成过程中过渡区组装的途径。初级纤毛是大多数动物细胞类型中发现的结构。就像天线一样，它负责感测细胞外信号，包括光和小分子，并将这些信息传递给接收细胞和相应的组织或器官。纤毛的底部是过渡区（TZ），它充当调节信号转导所需纤毛蛋白进出的“门”。在这里，我们使用线虫秀丽隐杆线虫作为模型系统来剖析 TZ 内不同蛋白质如何组装形成功能屏障。我们发现 TZ 蛋白 MKS-5（Rpgrip1/Rpgrip1L 直系同源物）构成了涉及两个不同模块的两种不同组装途径的基础：肾结核 (NPHP) 和梅克尔综合征 (MKS)。我们发现，MKS 模块的基础是 CEP-290，这是另一种组装 MKS 模块蛋白的 TZ 蛋白，其中包括我们鉴定为 TMEM-218 的新型 TZ 蛋白。 CEP-290 还有助于组装一个可能独立的包含 TMEM-138 和 CDKL-1 的子模块。值得注意的是，我们提供的证据表明，MKS 模块蛋白 TMEM-17 促进纤毛形成，并且在人类疾病（纤毛病）6 型口腔面部数字综合症 (OFD6) 中被破坏。总之，我们的研究结果为睫状 TZ 的组装途径提供了重要的见解，并提出了过渡区与人类健康之间的进一步联系。
Cilia have a unique diffusion barrier (“gate”) within their proximal region, termed transition zone (TZ), that compartmentalises signalling proteins within the organelle. The TZ is known to harbour two functional modules/complexes (Meckel syndrome [MKS] and Nephronophthisis [NPHP]) defined by genetic interaction, interdependent protein localisation (hierarchy), and proteomic studies. However, the composition and molecular organisation of these modules and their links to human ciliary disease are not completely understood. Here, we reveal Caenorhabditis elegans CEP-290 (mammalian Cep290/Mks4/Nphp6 orthologue) as a central assembly factor that is specific for established MKS module components and depends on the coiled coil region of MKS-5 (Rpgrip1L/Rpgrip1) for TZ localisation. Consistent with a critical role in ciliary gate function, CEP-290 prevents inappropriate entry of membrane-associated proteins into cilia and keeps ARL-13 (Arl13b) from leaking out of cilia via the TZ. We identify a novel MKS module component, TMEM-218 (Tmem218), that requires CEP-290 and other MKS module components for TZ localisation and functions together with the NPHP module to facilitate ciliogenesis. We show that TZ localisation of TMEM-138 (Tmem138) and CDKL-1 (Cdkl1/Cdkl2/Cdkl3/Cdlk4 related), not previously linked to a specific TZ module, similarly depends on CEP-290; surprisingly, neither TMEM-138 or CDKL-1 exhibit interdependent localisation or genetic interactions with core MKS or NPHP module components, suggesting they are part of a distinct, CEP-290-associated module. Lastly, we show that families presenting with Oral-Facial-Digital syndrome type 6 (OFD6) have likely pathogenic mutations in CEP-290-dependent TZ proteins, namely Tmem17, Tmem138, and Tmem231. Notably, patient fibroblasts harbouring mutated Tmem17, a protein not yet ciliopathy-associated, display ciliogenesis defects. Together, our findings expand the repertoire of MKS module-associated proteins—including the previously uncharacterised mammalian Tmem80—and suggest an MKS-5 and CEP-290-dependent assembly pathway for building a functional TZ. The transition zone is a barrier structure required to maintain the dynamic composition and functional integrity of the cilium. This study describes the pathway by which the transition zone is assembled during cilium formation. The primary cilium is a structure found in most animal cell types. Much like an antenna, it is responsible for sensing extracellular signals, including light and small molecules, and conveying this information to the receiving cell and respective tissue or organ. At the base of the cilium is the transition zone (TZ), which acts as a “gate” to regulate the entry and exit of ciliary proteins required for signal transduction. Here, we use the nematode Caenorhabditis elegans as a model system to dissect how different proteins within the TZ assemble to form a functional barrier. We find that the TZ protein MKS-5 (Rpgrip1/Rpgrip1L orthologue) forms the foundation for two different assembly pathways involving two distinct modules: Nephronophthisis (NPHP) and Meckel syndrome (MKS). We show that at the base of the MKS module is CEP-290, another TZ protein that assembles MKS module proteins, including a novel TZ protein we identify as TMEM-218. CEP-290 also helps assemble a potentially separate submodule containing TMEM-138 and CDKL-1. Notably, we provide evidence that the MKS module protein TMEM-17 facilitates cilium formation and is disrupted in the human disorder (ciliopathy) Oral-Facial-Digital Syndrome type 6 (OFD6). Together, our findings provide essential insights into the assembly pathway of the ciliary TZ and suggest further connections between the transition zone and human health.