title: Functional dissection of Rab GTPases involved in primary cilium formation.
abstract: Primary cilia are sensory structures involved in morphogen signalling during development, liquid flow in the kidney, mechanosensation, sight, and smell (Badano, J.L., N. Mitsuma, P.L. Beales, and N. Katsanis. 2006. Annu. Rev. Genomics Hum. Genet. 7:125-148; Singla, V., and J.F. Reiter. 2006. Science. 313:629-633.). Mutations that affect primary cilia are responsible for several diseases, including neural tube defects, polycystic kidney disease, retinal degeneration, and cancers (Badano et al., 2006; Singla and Reiter, 2006). Primary cilia formation and function requires tight integration of the microtubule cytoskeleton with membrane trafficking (Singla and Reiter, 2006), and this is poorly understood. We show that the Rab GTPase membrane trafficking regulators Rab8a, -17, and -23, and their cognate GTPase-activating proteins (GAPs), XM_037557, TBC1D7, and EVI5like, are involved in primary cilia formation. However, other human Rabs and GAPs are not. Additionally, Rab8a specifically interacts with cenexin/ODF2, a basal body and microtubule binding protein required for cilium biogenesis (Ishikawa, H., A. Kubo, S. Tsukita, and S. Tsukita. 2005. Nat. Cell Biol. 7:517-524), and is the sole Rab enriched at primary cilia. These findings provide a basis for understanding how specific membrane trafficking pathways cooperate with the microtubule cytoskeleton to give rise to the primary cilia.
authors.affiliation: University of Liverpool Cancer Research Centre, Liverpool, England, UK.
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Yoshimura
authors.forename: Johannes
authors.initials: J
authors.lastname: Egerer
authors.forename: Evelyn
authors.initials: E
authors.lastname: Fuchs
authors.forename: Alexander K
authors.initials: AK
authors.lastname: Haas
authors.forename: Francis A
authors.initials: FA
authors.lastname: Barr
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002923:Cilia / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D010857:Pigment Epithelium of Eye / Q000166:cytology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D006360:Heat-Shock Proteins; C490107:ODF2 protein, human; D011993:Recombinant Fusion Proteins; C082377:RAB8A protein, human; D020691:rab GTP-Binding Proteins