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Active transport and diffusion barriers restrict Joubert Syndrome-associated ARL13B/ARL-13 to an Inv-like ciliary membrane subdomain

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Item Type:Article
Title:Active transport and diffusion barriers restrict Joubert Syndrome-associated ARL13B/ARL-13 to an Inv-like ciliary membrane subdomain
Creators Name:Cevik, S. and Sanders, A.A.W.M. and Van Wijk, E. and Boldt, K. and Clarke, L. and van Reeuwijk, J. and Hori, Y. and Horn, N. and Hetterschijt, L. and Wdowicz, A. and Mullins, A. and Kida, K. and Kaplan, O.I. and van Beersum, S.E.C. and Man Wu, K. and Letteboer, S.J.F. and Mans, D.A. and Katada, T. and Kontani, K. and Ueffing, M. and Roepman, R. and Kremer, H. and Blacque, O.E.
Abstract:Cilia are microtubule-based cell appendages, serving motility, chemo-/mechano-/photo- sensation, and developmental signaling functions. Cilia are comprised of distinct structural and functional subregions including the basal body, transition zone (TZ) and inversin (Inv) compartments, and defects in this organelle are associated with an expanding spectrum of inherited disorders including Bardet-Biedl syndrome (BBS), Meckel-Gruber Syndrome (MKS), Joubert Syndrome (JS) and Nephronophthisis (NPHP). Despite major advances in understanding ciliary trafficking pathways such as intraflagellar transport (IFT), how proteins are transported to subciliary membranes remains poorly understood. Using Caenorhabditis elegans and mammalian cells, we investigated the transport mechanisms underlying compartmentalization of JS-associated ARL13B/ARL-13, which we previously found is restricted at proximal ciliary membranes. We now show evolutionary conservation of ARL13B/ARL-13 localisation to an Inv-like subciliary membrane compartment, excluding the TZ, in many C. elegans ciliated neurons and in a subset of mammalian ciliary subtypes. Compartmentalisation of C. elegans ARL-13 requires a C-terminal RVVP motif and membrane anchoring to prevent distal cilium and nuclear targeting, respectively. Quantitative imaging in more than 20 mutants revealed differential contributions for IFT and ciliopathy modules in defining the ARL-13 compartment; IFT-A/B, IFT-dynein and BBS genes prevent ARL-13 accumulation at periciliary membranes, whereas MKS/NPHP modules additionally inhibit ARL-13 association with TZ membranes. Furthermore, in vivo FRAP analyses revealed distinct roles for IFT and MKS/NPHP genes in regulating a TZ barrier to ARL-13 diffusion, and intraciliary ARL-13 diffusion. Finally, C. elegans ARL-13 undergoes IFT-like motility and quantitative protein complex analysis of human ARL13B identified functional associations with IFT-B complexes, mapped to IFT46 and IFT74 interactions. Together, these findings reveal distinct requirements for sequence motifs, IFT and ciliopathy modules in defining an ARL-13 subciliary membrane compartment. We conclude that MKS/NPHP modules comprise a TZ barrier to ARL-13 diffusion, whereas IFT genes predominantly facilitate ARL-13 ciliary entry and/or retention via active transport mechanisms.
Keywords:ADP-Ribosylation Factors, Active Biological Transport , Bardet-Biedl Syndrome, Caenorhabditis elegans, Cerebellar Diseases, Cilia, Ciliary Motility Disorders, Cystic Kidney Diseases , Cytoskeletal Proteins, Encephalocele, Eye Abnormalities, Membranes, Polycystic Kidney Diseases, Retina, Transcription Factors, Animals
Source:PLoS Genetics
Publisher:Public Library of Science
Page Range:e1003977
Date:December 2013
Official Publication:https://doi.org/10.1371/journal.pgen.1003977
PubMed:View item in PubMed

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