The long-term goal of this project is to understand the molecular basis of cilia formation and maintenance in vertebrate photoreceptor cells. In vertebrates, the assembly and maintenance of photoreceptor outer segments begins with the formation of a connecting cilium. The connecting cilium contains a microtubule- based axoneme that is anchored to the apical inner segment by a basal body. Cilia formation begins with the docking of basal bodies at the apical surface of the inner segment. Genetic mutations disrupting the assembly, structure, or function of basal bodies and/or cilia result in a spectrum of diseases known as ciliopathies. These multisyndromic disorders often present with retinal degeneration, kidney disease, mental retardation, and polydactyly. In the current application, we will utilize loss-of-function strategies in zebrafish to investigate the mechanisms controlling basal body localization.
In Specific Aim 1, we will test the hypothesis that the dynein/dynactin complex regulates the apical transport of basal bodies preceding cilia formation by examining zebrafish mutants in dynein and the p150 and p50 subunits of dynactin.
In Specific Aim 2, we provide preliminary evidence that basal bodies show a highly polarized arrangement within the adult zebrafish retina. We will directly test the hypothesis that the PCP pathway regulates this patterning and is essential for photoreceptor survival.
In Specific Aim 3, we will examine zebrafish carrying null mutations in the Joubert Syndrome gene arl13b for retinal phenotypes. Proposed experiments will also test the requirement of the GTPase domain and a ciliary-targeting sequence RVxPx for Arl13b function. We will also test arl13b for functional interactions with Bardet-Biedl Syndrome (BBS) genes, and components of the PCP pathway. These interactions will identify potential second-site modifiers that enhance expression of photoreceptor phenotypes. The results of these studies will reveal novel mechanisms required for basal body placement prior to cilia formation and to identify novel genetic interactions that influence hereditary blindness.

Public Health Relevance

The docking and anchoring of the basal body is essential for the formation of the connecting cilium and outer segment of vertebrate photoreceptors. The cilia/basal body structure is a complex organelle of great clinical importance because defects in cilia positioning, assembly or function lead to retinal degeneration, kidney disorders, mental retardation, situs inversus, polydactyly, and other conditions. An understanding of the mechanisms that control the cilia formation will lead to the development of treatments for ciliary diseases.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Special Emphasis Panel (BVS)
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Neuhold, Lisa
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Cleveland Clinic Lerner
Schools of Medicine
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Song, Ping; Perkins, Brian D (2018) Developmental expression of the zebrafish Arf-like small GTPase paralogs arl13a and arl13b. Gene Expr Patterns 29:82-87
Miller, Andrew H; Howe, Hollis B; Krause, Bryan M et al. (2018) Pregnancy-Associated Plasma Protein-aa Regulates Photoreceptor Synaptic Development to Mediate Visually Guided Behavior. J Neurosci 38:5220-5236
Lessieur, Emma M; Fogerty, Joseph; Gaivin, Robert J et al. (2017) The Ciliopathy Gene ahi1 Is Required for Zebrafish Cone Photoreceptor Outer Segment Morphogenesis and Survival. Invest Ophthalmol Vis Sci 58:448-460
Bell, Brent A; Yuan, Alex; Dicicco, Rose M et al. (2016) The adult zebrafish retina: In vivo optical sectioning with Confocal Scanning Laser Ophthalmoscopy and Spectral-Domain Optical Coherence Tomography. Exp Eye Res 153:65-78
Fogerty, Joseph; Denton, Kristin; Perkins, Brian D (2016) Mutations in the Dynein1 Complex are Permissible for Basal Body Migration in Photoreceptors but Alter Rab6 Localization. Adv Exp Med Biol 854:209-15
Song, Ping; Dudinsky, Lynn; Fogerty, Joseph et al. (2016) Arl13b Interacts With Vangl2 to Regulate Cilia and Photoreceptor Outer Segment Length in Zebrafish. Invest Ophthalmol Vis Sci 57:4517-26
Daniele, Lauren L; Emran, Farida; Lobo, Glenn P et al. (2016) Mutation of wrb, a Component of the Guided Entry of Tail-Anchored Protein Pathway, Disrupts Photoreceptor Synapse Structure and Function. Invest Ophthalmol Vis Sci 57:2942-54
Babino, Darwin; Perkins, Brian D; Kindermann, Aljoscha et al. (2015) The role of 11-cis-retinyl esters in vertebrate cone vision. FASEB J 29:216-26
DiCicco, Rose M; Bell, Brent A; Kaul, Charles et al. (2014) Retinal regeneration following OCT-guided laser injury in zebrafish. Invest Ophthalmol Vis Sci 55:6281-8
Krock, Bryan L; Perkins, Brian D (2014) The Par-PrkC polarity complex is required for cilia growth in zebrafish photoreceptors. PLoS One 9:e104661

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