title: Intraflagellar transport proteins in ciliogenesis of photoreceptor cells.
abstract: BACKGROUND
  The assembly and maintenance of cilia depend on IFT (intraflagellar transport) mediated by molecular motors and their interplay with IFT proteins. Here, we have analysed the involvement of IFT proteins in the ciliogenesis of mammalian photoreceptor cilia.
  
  
  RESULTS
  Electron microscopy revealed that ciliogenesis in mouse photoreceptor cells follows an intracellular ciliogenesis pathway, divided into six distinct stages. The first stages are characterized by electron-dense centriolar satellites and a ciliary vesicle, whereas the formations of the ciliary shaft and the light-sensitive outer segment discs are features of the later stages. IFT proteins were associated with ciliary apparatus during all stages of photoreceptor cell development.
  
  
  CONCLUSIONS
  Our data conclusively provide evidence for the participation of IFT proteins in photoreceptor cell ciliogenesis, including the formation of the ciliary vesicle and the elongation of the primary cilium. In advanced stages of ciliogenesis the ciliary localization of IFT proteins indicates a role in IFT as is seen in mature cilia. A prominent accumulation of IFT proteins in the periciliary cytoplasm at the base of the cilia in these stages most probably resembles a reserve pool of IFT molecules for further delivery into the growing ciliary shaft and their subsequent function in IFT. Nevertheless, the cytoplasmic localization of IFT proteins in the absence of a ciliary shaft in early stages of ciliogenesis may indicate roles of IFT proteins beyond their well-established function for IFT in mature cilia and flagella.
authors: Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University, Mainz, Germany.
authors: Tina
authors: T
authors: Sedmak
authors: Uwe
authors: U
authors: Wolfrum
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002923:Cilia / Q000502:physiology* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D046529:Microscopy, Electron, Transmission; D038081:Organogenesis; D010786:Photoreceptor Cells / Q000166:cytology / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000196:embryology
chemical_list: D002352:Carrier Proteins