Arl13b Interacts With Vangl2 to Regulate Cilia and Photoreceptor Outer Segment Length in Zebrafish

Song, P., Dudinsky, L., Fogerty, J., Gaivin, R., Perkins, B.D.
Investigative ophthalmology & visual science   57: 4517-4526 (Journal)
Registered Authors
Fogerty, Joseph, Gaivin, Bob, Perkins, Brian, Song, Ping
MeSH Terms
  • ADP-Ribosylation Factors/genetics*
  • ADP-Ribosylation Factors/metabolism
  • Animals
  • Blotting, Western
  • Cells, Cultured
  • Cilia/metabolism*
  • Cilia/ultrastructure
  • DNA
  • DNA Mutational Analysis
  • Disease Models, Animal
  • Immunohistochemistry
  • Immunoprecipitation
  • In Situ Hybridization
  • Larva
  • Microscopy, Electron
  • Mutation*
  • Retinal Degeneration/diagnosis*
  • Retinal Degeneration/metabolism
  • Retinal Photoreceptor Cell Outer Segment/metabolism*
  • Retinal Photoreceptor Cell Outer Segment/ultrastructure
  • Zebrafish
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/metabolism
27571019 Full text @ Invest. Ophthalmol. Vis. Sci.
Mutations in the gene ARL13B cause the classical form of Joubert syndrome, an autosomal recessive ciliopathy with variable degrees of retinal degeneration. As second-site modifier alleles can contribute to retinal pathology in ciliopathies, animal models provide a unique platform to test how genetic interactions modulate specific phenotypes. In this study, we analyzed the zebrafish arl13b mutant for retinal degeneration and for epistatic relationships with the planar cell polarity protein (PCP) component vangl2.
Photoreceptor and cilia structure was examined by light and electron microscopy. Immunohistochemistry was performed to examine ciliary markers. Genetic interactions were tested by pairwise crosses of heterozygous animals. Genetic mosaic animals were generated by blastula transplantation and analyzed by fluorescence microscopy.
At 5 days after fertilization, photoreceptor outer segments were shorter in zebrafish arl13b-/- mutants compared to wild-type larvae, no overt signs of retinal degeneration were observed by light or electron microscopy. Starting at 14 days after fertilization (dpf) and continuing through 30 dpf, cells lacking Arl13b died following transplantation into wild-type host animals. Photoreceptors of arl13b-/-;vangl2-/- mutants were more compromised than the photoreceptors of single mutants. Finally, when grown within a wild-type retina, the vangl2-/- mutant cone photoreceptors displayed normal basal body positioning.
We show that arl13b-/- mutants have shortened cilia and photoreceptor outer segments and exhibit a slow, progressive photoreceptor degeneration that occurs over weeks. The data suggest that loss of Arl13b leads to slow photoreceptor degeneration, but can be exacerbated by the loss of vangl2. Importantly, the data show that Arl13b can genetically and physically interact with Vangl2 and this association is important for normal photoreceptor structure. The loss of vangl2, however, does not affect basal body positioning.
Genes / Markers
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Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes