title: Knockdown of unc119c results in visual impairment and early-onset retinal dystrophy in zebrafish.
abstract: UNC119 proteins are involved in G protein trafficking in mouse retinal photoreceptors and Caenorhabditis elegans olfactory neurons. An Unc119 null allele is associated with cone-rod dystrophy in mouse, but the mechanism leading to disease is not understood. We studied the role of Unc119 paralogs and Arl3l2 in zebrafish vision and retinal organization resulting from unc119c and arl3l2 knockdown.
  
  
  
  Zebrafish unc119c was amplified by PCR from retina and pineal gland cDNA. Its expression pattern in the eye and pineal gland was determined by whole-mount in-situ hybridization. unc119c and arl3l2 were knocked down using morpholino-modified oligonucleotides (MO). Their visual function was assessed with a quantitative optomotor assay on 6 days post-fertilization larvae. Retinal morphology was analyzed using immunohistochemistry with anti-cone arrestin (zpr-1) and anti-cone transducin-α (GNAT2) antibodies.
  
  
  
  The zebrafish genome contains four genes encoding unc119 paralogs located on different chromosomes. The exon/intron arrangements of these genes are identical. Three Unc119 paralogs are expressed in the zebrafish retina, termed Unc119a-c. Based on sequence similarity, Unc119a and Unc119b are orthologs of mammalian UNC119a and UNC119b, respectively. A third, Unc119c, is unique and not present in mammals. Whole mount in-situ hybridization revealed that unc119a and unc119b RNA are ubiquitously expressed in the CNS, and unc119c is specifically expressed in photoreceptive tissues (pineal gland and retina). A Unc119 interactant, Arl3l2 also localizes to the pineal gland and the retina. As measured by the optomotor response, unc119c and arl3l2 knockdown resulted in significantly lower vision compared to wild-type zebrafish larvae and control morpholino (MO). Immunohistological analysis with anti-cone transducin and anti-cone arrestin (zpr-1) indicates that knockdown of unc119c leads to photoreceptor degeneration mostly affecting cones.
  
  
  
  Our results suggest that Unc119c is the only Unc119 paralog that is highly specific to the retina in zebrafish. Unc119c and Arl3l2 proteins are important for the function of cones.
authors.affiliation: Department of Neurobiology, George S. Wise Faculty of Life Sciences, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Rainy
authors.affiliation: Department of Neurobiology, George S. Wise Faculty of Life Sciences, Israel.
authors.forename: Talya
authors.initials: T
authors.lastname: Etzion
authors.affiliation: Department of Neurobiology, George S. Wise Faculty of Life Sciences, Israel; Sagol School of Neuroscience Tel Aviv University, Israel.
authors.forename: Shahar
authors.initials: S
authors.lastname: Alon
authors.affiliation: Department of Neurobiology, George S. Wise Faculty of Life Sciences, Israel.
authors.forename: Adi
authors.initials: A
authors.lastname: Pomeranz
authors.affiliation: Laboratory of Eye Research, Felsenstein Medical Research Center Israel, Petah Tikva, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Nisgav
authors.affiliation: Laboratory of Eye Research, Felsenstein Medical Research Center Israel, Petah Tikva, Israel.
authors.forename: Tami
authors.initials: T
authors.lastname: Livnat
authors.affiliation: Eye Center, Medical Center, University of Freiburg, Killianstraße 5, 79106, Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bach
authors.affiliation: Department of Ophthalmology and Department of Neurobiology and Anatomy, University of Utah Health Science Center, Salt Lake City, UT 84132, USA.
authors.forename: Cecilia D
authors.initials: CD
authors.lastname: Gerstner
authors.affiliation: Department of Ophthalmology and Department of Neurobiology and Anatomy, University of Utah Health Science Center, Salt Lake City, UT 84132, USA; Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baehr
authors.affiliation: Department of Neurobiology, George S. Wise Faculty of Life Sciences, Israel; Sagol School of Neuroscience Tel Aviv University, Israel.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Gothilf
authors.affiliation: Department of Ophthalmology at Rabin Medical Center, Petah Tikva & Sackler Faculty of Medicine, Tel Aviv University, Israel. Electronic address: kalishhadas@gmail.com.
authors.forename: Hadas
authors.initials: H
authors.lastname: Stiebel-Kalish
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D015785:Eye Diseases, Hereditary / Q000150:complications* / Q000473:pathology / Q000503:physiopathology*; D055785:Gene Knockdown Techniques; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism* / Q000473:pathology; D058499:Retinal Dystrophies / Q000150:complications* / Q000473:pathology / Q000503:physiopathology*; D014786:Vision Disorders / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology*; D015027:Zebrafish
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C098032:UNC119 protein, human
keywords: Morpholino knockdown; Retina degeneration; Uncoordinated (UNC) 119; Zebrafish retina