title: Cluap1 is essential for ciliogenesis and photoreceptor maintenance in the vertebrate eye.
abstract: OBJECTIVE
  To identify the mutation and cell biological underpinnings of photoreceptor defects in zebrafish au5 mutants.
  
  
  METHODS
  Whole genome sequencing and SNP mapping were used to determine the genomic interval that harbors the au5 mutation. A candidate mutation was cloned and sequenced, and mRNA rescue used to validate that the affected gene was correctly identified. In situ hybridization, immunohistochemistry, and confocal imaging were used to determine the effects on photoreceptor development and maintenance in mutant retinae, and to determine if ciliogenesis or cilia-dependent development was affected in mutant embryos. Expression of tagged proteins and high-speed in vivo confocal imaging was used to quantify intraflagellar transport (IFT) and IFT particle localization within multiciliated cells of the Xenopus epidermis.
  
  
  RESULTS
  The au5 mutants possess a nonsense mutation in cluap1, which encodes a component of the IFT machinery. Photoreceptor defects result from degeneration of photoreceptors, and defects in ciliogenesis precede degeneration. Cilia in the olfactory pit are absent, and left-right heart positioning is aberrant, consistent with a role for cluap1 during ciliogenesis and cilia-dependent development. High-speed in vivo imaging demonstrates that cluap1 undergoes IFT and that it moves along the cilium bidirectionally, with similar localization and kinetics as IFT20, an IFT-B complex component.
  
  
  CONCLUSIONS
  We identified a novel mutation in cluap1 and determined that photoreceptor maintenance is dependent on cluap1. Imaging data support a model in which cluap1 is a component of the IFT-B complex, and cilia formation requires cluap1 function. These data may provide new insights into the mechanism of photoreceptor degeneration in retinal ciliopathies.
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States.
authors: Chanjae
authors: C
authors: Lee
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States Howard Hughes Medical Institute, The University of Texas at Austin, Austin, Texas, United States.
authors: John B
authors: JB
authors: Wallingford
authors: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States.
authors: Jeffrey M
authors: JM
authors: Gross
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D000818:Animals; D002923:Cilia / Q000502:physiology*; D018389:Codon, Nonsense; D019084:Fluorescent Antibody Technique, Indirect; D005822:Genetic Vectors; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D009024:Morphogenesis / Q000502:physiology*; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D020641:Polymorphism, Single Nucleotide; D012333:RNA, Messenger / Q000235:genetics; D012162:Retinal Degeneration / Q000378:metabolism / Q000503:physiopathology; D014982:Xenopus laevis; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins / Q000502:physiology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018389:Codon, Nonsense; D012333:RNA, Messenger; D029961:Zebrafish Proteins
keywords: cilia; cluap1; photoreceptor degeneration; zebrafish