Li Chunmei, Jensen Victor L, Park Kwangjin, Kennedy Julie, Garcia-Gonzalo Francesc R, Romani Marta, De Mori Roberta, Bruel Ange-Line, Gaillard Dominique, Doray Bérénice, Lopez Estelle, Rivière Jean-Baptiste, Faivre Laurence, Thauvin-Robinet Christel, Reiter Jeremy F, Blacque Oliver E, Valente Enza Maria, Leroux Michel R
Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, British Columbia, Canada.
School of Biomolecular & Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland.
PLoS Biol. 2016 Mar 16;14(3):e1002416. doi: 10.1371/journal.pbio.1002416. eCollection 2016 Mar.
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.
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分隔开来。已知TZ包含两个由遗传相互作用、相互依赖的蛋白质定位（层次结构）和蛋白质组学研究定义的功能模块/复合体（梅克尔综合征 [MKS] 和肾单位肾痨 [NPHP]）。然而，这些模块的组成和分子组织及其与人类纤毛疾病的联系尚未完全了解。在这里，我们揭示秀丽隐杆线虫的CEP-290（哺乳动物Cep290/Mks4/Nphp6的直系同源物）是一种核心组装因子，它对已确定的MKS模块组件具有特异性，并且其TZ定位依赖于MKS-5（Rpgrip1L/Rpgrip1）的卷曲螺旋区域。与在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进入纤毛，并防止ARL-13（Arl13b）通过TZ从纤毛中泄漏出去。我们鉴定出一种新型的MKS模块组件TMEM-218（Tmem218），其TZ定位需要CEP-290和其他MKS模块组件，并与NPHP模块一起发挥作用以促进纤毛发生。我们表明，之前未与特定TZ模块相关联的TMEM-138（Tmem138）和CDKL-1（Cdkl1/Cdkl2/Cdkl3/Cdlk4相关蛋白）的TZ定位同样依赖于CEP-290；令人惊讶的是，TMEM-138和CDKL-1均未表现出与核心MKS或NPHP模块组件的相互依赖定位或遗传相互作用，这表明它们是一个独特的、与CEP-290相关的模块的一部分。最后，我们表明患有6型口面指综合征（OFD6）的家族在CEP-290依赖性TZ蛋白，即Tmem17、Tmem138和Tmem231中可能存在致病性突变。值得注意的是，携带突变Tmem17（一种尚未与纤毛病相关的蛋白）的患者成纤维细胞表现出纤毛发生缺陷。总之，我们的发现扩展了与MKS模块相关的蛋白质库——包括之前未被表征的哺乳动物Tmem80——并提出了一种依赖于MKS-5和CEP-290的组装途径来构建功能性TZ。
Zotero 插件
