title: Functional characterization of Prickle2 and BBS7 identify overlapping phenotypes yet distinct mechanisms.
abstract: Ciliopathies are genetic disorders that are caused by dysfunctional cilia and affect multiple organs. One type of ciliopathy, Bardet-Biedl syndrome, is a rare disorder characterized by obesity, retinitis pigmentosa, polydactyly, mental retardation and susceptibility to cardiovascular diseases. The Wnt/Planar cell polarity (PCP) has been associated with cilia function and ciliogenesis in directing the orientation of cilia and basal bodies. Yet the exact relationship between PCP and ciliopathy is not well understood. Here, we examine interactions between a core PCP component, Prickle2 (Pk2), and a central BBS gene, Bbs7, using gene knockdown in the zebrafish. pk2 and bbs7 knockdown both disrupt the formation of a ciliated organ, the Kupffer׳s vesicle (KV), but do not display a synergistic interaction. By measuring cell polarity in the neural tube, we find that bbs7 activity is not required for Pk asymmetric localization. Moreover, BBS protein complex formation is preserved in the Pk2-deficient (Pk2(-/-)) mouse. Previously we reported an intracellular melanosome transport delay as a cardinal feature of reduced bbs gene activity. We find that pk2 knockdown suppresses bbs7-related retrograde transport delay. Similarly, knockdown of ift22, an anterograde intraflagellar transport component, also suppresses the bbs7-related retrograde delay. Notably, we find that pk2 knockdown larvae show a delay in anterograde transport. These data suggest a novel role for Pk2 in directional intracellular transport and our analyses show that PCP and BBS function independently, yet result in overlapping phenotypes when knocked down in zebrafish.
authors.affiliation: Department of Biology, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Xue
authors.initials: X
authors.lastname: Mei
authors.affiliation: Department of Biology, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Trudi A
authors.initials: TA
authors.lastname: Westfall
authors.affiliation: Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; Howard Hughes Medical Institute, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
authors.forename: Qihong
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; Howard Hughes Medical Institute, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
authors.forename: Val C
authors.initials: VC
authors.lastname: Sheffield
authors.affiliation: Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Bassuk
authors.affiliation: Department of Biology, University of Iowa, Iowa City, IA 52242, USA. Electronic address: diane-slusarski@uiowa.edu.
authors.forename: Diane C
authors.initials: DC
authors.lastname: Slusarski
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000704:Analysis of Variance; D000818:Animals; D020788:Bardet-Biedl Syndrome / Q000235:genetics*; D001692:Biological Transport / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology*; D002923:Cilia / Q000473:pathology; D003598:Cytoskeletal Proteins; D017931:DNA Primers / Q000235:genetics; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D017403:In Situ Hybridization; D060588:LIM Domain Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D018832:Molecular Chaperones / Q000378:metabolism*; D060172:Morpholinos / Q000235:genetics; D054259:Neural Tube / Q000166:cytology / Q000196:embryology*; D055495:Neurogenesis / Q000502:physiology*; D012160:Retina / Q000196:embryology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015027:Zebrafish
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C584290:BBS7 protein, mouse; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D060588:LIM Domain Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D060172:Morpholinos; C518732:Prickle2 protein, mouse
keywords: Bardet–Biedl syndrome; Cilia; Intracellular transport; Kupffer׳s vesicle; Planar cell polarity; Prickle2; Retinal neurogenesis; Zebrafish