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Xu J, Zhao C, Kang Y. The Formation and Renewal of Photoreceptor Outer Segments. Cells 2024; 13:1357. [PMID: 39195247 DOI: 10.3390/cells13161357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2024] [Revised: 08/12/2024] [Accepted: 08/13/2024] [Indexed: 08/29/2024] Open
Abstract
The visual system is essential for humans to perceive the environment. In the retina, rod and cone photoreceptor neurons are the initial sites where vision forms. The apical region of both cone and rod photoreceptors contains a light-sensing organelle known as the outer segment (OS), which houses tens of thousands of light-sensitive opsins. The OSs of photoreceptors are not static; they require rhythmic renewal to maintain normal physiological functions. Disruptions in OS renewal can lead to various genetic disorders, such as retinitis pigmentosa (RP). Understanding the patterns and molecular mechanisms of photoreceptor OS renewal remains one of the most intriguing topics in visual biology. This review aims to elucidate the structure of photoreceptor OSs, the molecular mechanisms underlying photoreceptor OS renewal, and the retinal diseases resulting from defects in this renewal process. Additionally, we will explore retinal diseases related to photoreceptor OS renewal and potential therapeutic strategies, concluding with a discussion on future research directions for OS renewal.
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Affiliation(s)
- Jingjin Xu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
- MoE Key Laboratory of Evolution and Marine Biodiversity, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Chengtian Zhao
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
- MoE Key Laboratory of Evolution and Marine Biodiversity, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Yunsi Kang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
- MoE Key Laboratory of Evolution and Marine Biodiversity, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
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2
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Waas B, Carpenter BS, Franks NE, Merchant OQ, Verhey KJ, Allen BL. Dual and opposing roles for the kinesin-2 motor, KIF17, in Hedgehog-dependent cerebellar development. SCIENCE ADVANCES 2024; 10:eade1650. [PMID: 38669326 PMCID: PMC11051677 DOI: 10.1126/sciadv.ade1650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 03/26/2024] [Indexed: 04/28/2024]
Abstract
While the kinesin-2 motors KIF3A and KIF3B have essential roles in ciliogenesis and Hedgehog (HH) signal transduction, potential role(s) for another kinesin-2 motor, KIF17, in HH signaling have yet to be explored. Here, we investigated the contribution of KIF17 to HH-dependent cerebellar development, where Kif17 is expressed in both HH-producing Purkinje cells and HH-responding cerebellar granule neuron progenitors (CGNPs). Germline Kif17 deletion in mice results in cerebellar hypoplasia due to reduced CGNP proliferation, a consequence of decreased HH pathway activity mediated through decreased Sonic HH (SHH) protein. Notably, Purkinje cell-specific Kif17 deletion partially phenocopies Kif17 germline mutants. Unexpectedly, CGNP-specific Kif17 deletion results in the opposite phenotype-increased CGNP proliferation and HH target gene expression due to altered GLI transcription factor processing. Together, these data identify KIF17 as a key regulator of HH-dependent cerebellar development, with dual and opposing roles in HH-producing Purkinje cells and HH-responding CGNPs.
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Affiliation(s)
- Bridget Waas
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Brandon S. Carpenter
- Department of Molecular and Cellular Biology, College of Science and Mathematics, Kennesaw State University, Kennesaw, GA, 30061, USA
| | - Nicole E. Franks
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Olivia Q. Merchant
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kristen J. Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Benjamin L. Allen
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
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3
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Li L, Ran J. Regulation of ciliary homeostasis by intraflagellar transport-independent kinesins. Cell Death Dis 2024; 15:47. [PMID: 38218748 PMCID: PMC10787775 DOI: 10.1038/s41419-024-06428-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 12/20/2023] [Accepted: 01/02/2024] [Indexed: 01/15/2024]
Abstract
Cilia are highly conserved eukaryotic organelles that protrude from the cell surface and are involved in sensory perception, motility, and signaling. Their proper assembly and function rely on the bidirectional intraflagellar transport (IFT) system, which involves motor proteins, including antegrade kinesins and retrograde dynein. Although the role of IFT-mediated transport in cilia has been extensively studied, recent research has highlighted the contribution of IFT-independent kinesins in ciliary processes. The coordinated activities and interplay between IFT kinesins and IFT-independent kinesins are crucial for maintaining ciliary homeostasis. In this comprehensive review, we aim to delve into the specific contributions and mechanisms of action of the IFT-independent kinesins in cilia. By shedding light on their involvement, we hope to gain a more holistic perspective on ciliogenesis and ciliopathies.
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Affiliation(s)
- Lin Li
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, College of Life Sciences, Shandong Normal University, Jinan, 250014, China
| | - Jie Ran
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, College of Life Sciences, Shandong Normal University, Jinan, 250014, China.
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4
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Liu J, Xie H, Wu M, Hu Y, Kang Y. The role of cilia during organogenesis in zebrafish. Open Biol 2023; 13:230228. [PMID: 38086423 PMCID: PMC10715920 DOI: 10.1098/rsob.230228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 11/03/2023] [Indexed: 12/18/2023] Open
Abstract
Cilia are hair-like organelles that protrude from the surface of eukaryotic cells and are present on the surface of nearly all human cells. Cilia play a crucial role in signal transduction, organ development and tissue homeostasis. Abnormalities in the structure and function of cilia can lead to a group of human diseases known as ciliopathies. Currently, zebrafish serves as an ideal model for studying ciliary function and ciliopathies due to its relatively conserved structure and function of cilia compared to humans. In this review, we will summarize the different types of cilia that present in embryonic and adult zebrafish, and provide an overview of the advantages of using zebrafish as a vertebrate model for cilia research. We will specifically focus on the roles of cilia during zebrafish organogenesis based on recent studies. Additionally, we will highlight future prospects for ciliary research in zebrafish.
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Affiliation(s)
- Junjun Liu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Haibo Xie
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Mengfan Wu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Yidan Hu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
| | - Yunsi Kang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, People's Republic of China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, People's Republic of China
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5
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Masek M, Bachmann-Gagescu R. Control of protein and lipid composition of photoreceptor outer segments-Implications for retinal disease. Curr Top Dev Biol 2023; 155:165-225. [PMID: 38043951 DOI: 10.1016/bs.ctdb.2023.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Vision is arguably our most important sense, and its loss brings substantial limitations to daily life for affected individuals. Light is perceived in retinal photoreceptors (PRs), which are highly specialized neurons subdivided into several compartments with distinct functions. The outer segments (OSs) of photoreceptors represent highly specialized primary ciliary compartments hosting the phototransduction cascade, which transforms incoming light into a neuronal signal. Retinal disease can result from various pathomechanisms originating in distinct subcompartments of the PR cell, or in the retinal pigment epithelium which supports the PRs. Dysfunction of primary cilia causes human disorders known as "ciliopathies", in which retinal disease is a common feature. This chapter focuses on PR OSs, discussing the mechanisms controlling their complex structure and composition. A sequence of tightly regulated sorting and trafficking events, both upstream of and within this ciliary compartment, ensures the establishment and maintenance of the adequate proteome and lipidome required for signaling in response to light. We discuss in particular our current understanding of the role of ciliopathy proteins involved in multi-protein complexes at the ciliary transition zone (CC2D2A) or BBSome (BBS1) and how their dysfunction causes retinal disease. While the loss of CC2D2A prevents the fusion of vesicles and delivery of the photopigment rhodopsin to the ciliary base, leading to early OS ultrastructural defects, BBS1 deficiency results in precocious accumulation of cholesterol in mutant OSs and decreased visual function preceding morphological changes. These distinct pathomechanisms underscore the central role of ciliary proteins involved in multiple processes controlling OS protein and lipid composition.
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Affiliation(s)
- Markus Masek
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland; Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Ruxandra Bachmann-Gagescu
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland; Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland; University Research Priority Program AdaBD, University of Zurich, Zurich, Switzerland.
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6
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Juhl AD, Anvarian Z, Kuhns S, Berges J, Andersen JS, Wüstner D, Pedersen LB. Transient accumulation and bidirectional movement of KIF13B in primary cilia. J Cell Sci 2022; 136:275012. [DOI: 10.1242/jcs.259257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 04/01/2022] [Indexed: 10/18/2022] Open
Abstract
Primary cilia are microtubule-based sensory organelles whose assembly and function rely on the conserved bidirectional intraflagellar transport (IFT) system, which is powered by anterograde kinesin-2 and retrograde cytoplasmic dynein 2 motors. Nematodes additionally employ a cell type-specific kinesin-3 motor, KLP-6, which moves within cilia independently of IFT and regulates ciliary content and function. Here we provide evidence that a KLP-6 homolog, KIF13B, undergoes bursts of bidirectional movement within primary cilia of cultured immortalized human retinal pigment epithelial (hTERT-RPE1) cells. Anterograde and retrograde intraciliary velocities of KIF13B were similar to those of IFT (IFT172-eGFP), but intraciliary movement of KIF13B required its own motor domain and appeared to be cell-type specific. Our work provides the first demonstration of motor-driven, intraciliary movement by a vertebrate kinesin other than kinesin-2 motors.
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Affiliation(s)
- Alice Dupont Juhl
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Zeinab Anvarian
- Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
| | - Stefanie Kuhns
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Julia Berges
- Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
- Department of Biomedicine, Facultad Ciencias Experimentales, Universidad Francisco de Vitoria, Ctra. Pozuelo-Majadahonda Km. 1.800, 28223 Pozuelo de Alarcón (Madrid), Spain
| | - Jens S. Andersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Lotte B. Pedersen
- Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
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7
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Kanamaru T, Neuner A, Kurtulmus B, Pereira G. Balancing the length of the distal tip by septins is key for stability and signalling function of primary cilia. EMBO J 2022; 41:e108843. [PMID: 34981518 PMCID: PMC8724769 DOI: 10.15252/embj.2021108843] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 10/19/2021] [Accepted: 10/26/2021] [Indexed: 01/08/2023] Open
Abstract
Primary cilia are antenna-like organelles required for signalling transduction. How cilia structure is mechanistically maintained at steady-state to promote signalling is largely unknown. Here, we define that mammalian primary cilia axonemes are formed by proximal segment (PS) and distal segment (DS) delineated by tubulin polyglutamylation-rich and -poor regions, respectively. The analysis of proximal/distal segmentation indicated that perturbations leading to cilia over-elongation influenced PS or DS length with a different impact on cilia behaviour. We identified septins as novel repressors of DS growth. We show that septins control the localisation of MKS3 and CEP290 required for a functional transition zone (TZ), and the cilia tip accumulation of the microtubule-capping kinesin KIF7, a cilia-growth inhibitor. Live-cell imaging and analysis of sonic-hedgehog (SHH) signalling activation established that DS over-extension increased cilia ectocytosis events and decreased SHH activation. Our data underlines the importance of understanding cilia segmentation for length control and cilia-dependent signalling.
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Affiliation(s)
- Taishi Kanamaru
- Centre for Organismal Studies (COS)University of HeidelbergHeidelbergGermany
- German Cancer Research Centre (DKFZ)DKFZ‐ZMBH AllianceHeidelbergGermany
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
| | - Annett Neuner
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
| | - Bahtiyar Kurtulmus
- Centre for Organismal Studies (COS)University of HeidelbergHeidelbergGermany
- German Cancer Research Centre (DKFZ)DKFZ‐ZMBH AllianceHeidelbergGermany
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
| | - Gislene Pereira
- Centre for Organismal Studies (COS)University of HeidelbergHeidelbergGermany
- German Cancer Research Centre (DKFZ)DKFZ‐ZMBH AllianceHeidelbergGermany
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
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8
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Wensel TG, Potter VL, Moye A, Zhang Z, Robichaux MA. Structure and dynamics of photoreceptor sensory cilia. Pflugers Arch 2021; 473:1517-1537. [PMID: 34050409 PMCID: PMC11216635 DOI: 10.1007/s00424-021-02564-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 02/06/2023]
Abstract
The rod and cone photoreceptor cells of the vertebrate retina have highly specialized structures that enable them to carry out their function of light detection over a broad range of illumination intensities with optimized spatial and temporal resolution. Most prominent are their unusually large sensory cilia, consisting of outer segments packed with photosensitive disc membranes, a connecting cilium with many features reminiscent of the primary cilium transition zone, and a pair of centrioles forming a basal body which serves as the platform upon which the ciliary axoneme is assembled. These structures form a highway through which an enormous flux of material moves on a daily basis to sustain the continual turnover of outer segment discs and the energetic demands of phototransduction. After decades of study, the details of the fine structure and distribution of molecular components of these structures are still incompletely understood, but recent advances in cellular imaging techniques and animal models of inherited ciliary defects are yielding important new insights. This knowledge informs our understanding both of the mechanisms of trafficking and assembly and of the pathophysiological mechanisms of human blinding ciliopathies.
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Affiliation(s)
- Theodore G Wensel
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology and Developmental Biology Graduate Program, Baylor College of Medicine, Houston, TX, 77030, USA.
| | - Valencia L Potter
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology and Developmental Biology Graduate Program, Baylor College of Medicine, Houston, TX, 77030, USA
- Medical Scientist Training Program (MSTP), Baylor College of Medicine, Houston, TX, 77030, USA
| | - Abigail Moye
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Zhixian Zhang
- Vera and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Michael A Robichaux
- Departments of Ophthalmology and Biochemistry, West Virginia University, Morgantown, WV, USA
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9
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Zang J, Neuhauss SCF. Biochemistry and physiology of zebrafish photoreceptors. Pflugers Arch 2021; 473:1569-1585. [PMID: 33598728 PMCID: PMC8370914 DOI: 10.1007/s00424-021-02528-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 02/06/2023]
Abstract
All vertebrates share a canonical retina with light-sensitive photoreceptors in the outer retina. These photoreceptors are of two kinds: rods and cones, adapted to low and bright light conditions, respectively. They both show a peculiar morphology, with long outer segments, comprised of ordered stacks of disc-shaped membranes. These discs host numerous proteins, many of which contribute to the visual transduction cascade. This pathway converts the light stimulus into a biological signal, ultimately modulating synaptic transmission. Recently, the zebrafish (Danio rerio) has gained popularity for studying the function of vertebrate photoreceptors. In this review, we introduce this model system and its contribution to our understanding of photoreception with a focus on the cone visual transduction cascade.
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Affiliation(s)
- Jingjing Zang
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrase 190, CH - 8057, Zürich, Switzerland
| | - Stephan C F Neuhauss
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrase 190, CH - 8057, Zürich, Switzerland.
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10
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Barnes CL, Malhotra H, Calvert PD. Compartmentalization of Photoreceptor Sensory Cilia. Front Cell Dev Biol 2021; 9:636737. [PMID: 33614665 PMCID: PMC7889997 DOI: 10.3389/fcell.2021.636737] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/07/2021] [Indexed: 12/12/2022] Open
Abstract
Functional compartmentalization of cells is a universal strategy for segregating processes that require specific components, undergo regulation by modulating concentrations of those components, or that would be detrimental to other processes. Primary cilia are hair-like organelles that project from the apical plasma membranes of epithelial cells where they serve as exclusive compartments for sensing physical and chemical signals in the environment. As such, molecules involved in signal transduction are enriched within cilia and regulating their ciliary concentrations allows adaptation to the environmental stimuli. The highly efficient organization of primary cilia has been co-opted by major sensory neurons, olfactory cells and the photoreceptor neurons that underlie vision. The mechanisms underlying compartmentalization of cilia are an area of intense current research. Recent findings have revealed similarities and differences in molecular mechanisms of ciliary protein enrichment and its regulation among primary cilia and sensory cilia. Here we discuss the physiological demands on photoreceptors that have driven their evolution into neurons that rely on a highly specialized cilium for signaling changes in light intensity. We explore what is known and what is not known about how that specialization appears to have driven unique mechanisms for photoreceptor protein and membrane compartmentalization.
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Affiliation(s)
| | | | - Peter D. Calvert
- Department of Ophthalmology and Visual Sciences, Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY, United States
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11
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Konjikusic MJ, Gray RS, Wallingford JB. The developmental biology of kinesins. Dev Biol 2021; 469:26-36. [PMID: 32961118 PMCID: PMC10916746 DOI: 10.1016/j.ydbio.2020.09.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/10/2020] [Accepted: 09/14/2020] [Indexed: 02/06/2023]
Abstract
Kinesins are microtubule-based motor proteins that are well known for their key roles in cell biological processes ranging from cell division, to intracellular transport of mRNAs, proteins, vesicles, and organelles, and microtubule disassembly. Interestingly, many of the ~45 distinct kinesin genes in vertebrate genomes have also been associated with specific phenotypes in embryonic development. In this review, we highlight the specific developmental roles of kinesins, link these to cellular roles reported in vitro, and highlight remaining gaps in our understanding of how this large and important family of proteins contributes to the development and morphogenesis of animals.
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Affiliation(s)
- Mia J Konjikusic
- Department of Molecular Biosciences, USA; Department of Nutritional Sciences, University of Texas at Austin, USA
| | - Ryan S Gray
- Department of Nutritional Sciences, University of Texas at Austin, USA.
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12
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Review: Intraflagellar transport proteins in the retina. Mol Vis 2020; 26:652-660. [PMID: 33088169 PMCID: PMC7553723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 10/02/2020] [Indexed: 10/28/2022] Open
Abstract
Intraflagellar transport (IFT) is an essential process in all organisms that serves to move proteins along flagella or cilia in either direction. IFT is performed by IFT particles, which are multiprotein complexes organized into two subcomplexes, A and B. The IFT proteins form interactions with each other, with cargo proteins, and with membranes during the transport process. Several IFT proteins are expressed in many parts of the retina, such as the outer plexiform and outer nuclear layers, and function in the transport of photoreceptor proteins between the inner and outer segments. Mutants of IFT protein genes have been characterized in model organisms such as Chlamydomonas, C. elegans, zebrafish, and the mouse. These mutants have defective ciliogenesis or abnormalities in retinal photoreceptors. Mutations in IFT genes are associated with syndromic and non-syndromic forms of retinal disease in humans, frequently with early onset of disease.
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13
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Girardet L, Augière C, Asselin MP, Belleannée C. Primary cilia: biosensors of the male reproductive tract. Andrology 2019; 7:588-602. [PMID: 31131532 DOI: 10.1111/andr.12650] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/16/2019] [Accepted: 04/17/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND The primary cilium is a microtubule-based organelle that extends transiently from the apical cell surface to act as a sensory antenna. Initially viewed as a cellular appendage of obscure significance, the primary cilium is now acknowledged as a key coordinator of signaling pathways during development and in tissue homeostasis. OBJECTIVES The aim of this review was to present the structure and function of this overlooked organelle,with an emphasis on its epididymal context and contribution to male infertility issues. MATERIALS AND METHODS A systematic review has been performed in order to include main references relevant to the aforementioned topic. RESULTS Increasing evidence demonstrates that primary cilia dysfunctions are associated with impaired male reproductive system development and male infertility issues. DISCUSSION While a large amount of data exists regarding the role of primary cilia in most organs and tissues, few studies investigated the contribution of these organelles to male reproductive tract development and homeostasis. CONCLUSION Functional studies of primary cilia constitute an emergent and exciting new area in reproductive biology research.
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Affiliation(s)
- Laura Girardet
- Department of Obstetrics, Gynecology and Reproduction, Université Laval, CHU de Québec Research Center (CHUL), Quebec City, QC, Canada
| | - Céline Augière
- Department of Obstetrics, Gynecology and Reproduction, Université Laval, CHU de Québec Research Center (CHUL), Quebec City, QC, Canada
| | - Marie-Pier Asselin
- Department of Obstetrics, Gynecology and Reproduction, Université Laval, CHU de Québec Research Center (CHUL), Quebec City, QC, Canada
| | - Clémence Belleannée
- Department of Obstetrics, Gynecology and Reproduction, Université Laval, CHU de Québec Research Center (CHUL), Quebec City, QC, Canada
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14
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Reilly ML, Benmerah A. Ciliary kinesins beyond IFT: Cilium length, disassembly, cargo transport and signalling. Biol Cell 2019; 111:79-94. [PMID: 30720881 DOI: 10.1111/boc.201800074] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/18/2019] [Indexed: 02/06/2023]
Abstract
Cilia and flagella are microtubule-based antenna which are highly conserved among eukaryotes. In vertebrates, primary and motile cilia have evolved to exert several key functions during development and tissue homoeostasis. Ciliary dysfunction in humans causes a highly heterogeneous group of diseases called ciliopathies, a class of genetic multisystemic disorders primarily affecting kidney, skeleton, retina, lung and the central nervous system. Among key ciliary proteins, kinesin family members (KIF) are microtubule-interacting proteins involved in many diverse cellular functions, including transport of cargo (organelles, proteins and lipids) along microtubules and regulating the dynamics of cytoplasmic and spindle microtubules through their depolymerising activity. Many KIFs are also involved in diverse ciliary functions including assembly/disassembly, motility and signalling. We here review these ciliary kinesins in vertebrates and focus on their involvement in ciliopathy-related disorders.
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Affiliation(s)
- Madeline Louise Reilly
- Laboratory of Hereditary Kidney Diseases, INSERM UMR 1163, Paris Descartes University, Imagine Institute, Paris, 75015, France.,Paris Diderot University, Paris, 75013, France
| | - Alexandre Benmerah
- Laboratory of Hereditary Kidney Diseases, INSERM UMR 1163, Paris Descartes University, Imagine Institute, Paris, 75015, France
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15
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Konjikusic MJ, Yeetong P, Boswell CW, Lee C, Roberson EC, Ittiwut R, Suphapeetiporn K, Ciruna B, Gurnett CA, Wallingford JB, Shotelersuk V, Gray RS. Mutations in Kinesin family member 6 reveal specific role in ependymal cell ciliogenesis and human neurological development. PLoS Genet 2018; 14:e1007817. [PMID: 30475797 PMCID: PMC6307780 DOI: 10.1371/journal.pgen.1007817] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 12/27/2018] [Accepted: 11/07/2018] [Indexed: 01/06/2023] Open
Abstract
Cerebrospinal fluid flow is crucial for neurodevelopment and homeostasis of the ventricular system of the brain, with localized flow being established by the polarized beating of the ependymal cell (EC) cilia. Here, we report a homozygous one base-pair deletion, c.1193delT (p.Leu398Glnfs*2), in the Kinesin Family Member 6 (KIF6) gene in a child displaying neurodevelopmental defects and intellectual disability. To test the pathogenicity of this novel human KIF6 mutation we engineered an analogous C-terminal truncating mutation in mouse. These mutant mice display severe, postnatal-onset hydrocephalus. We generated a Kif6-LacZ transgenic mouse strain and report expression specifically and uniquely within the ependymal cells (ECs) of the brain, without labeling other multiciliated mouse tissues. Analysis of Kif6 mutant mice with scanning electron microscopy (SEM) and immunofluorescence (IF) revealed specific defects in the formation of EC cilia, without obvious effect of cilia of other multiciliated tissues. Dilation of the ventricular system and defects in the formation of EC cilia were also observed in adult kif6 mutant zebrafish. Finally, we report Kif6-GFP localization at the axoneme and basal bodies of multi-ciliated cells (MCCs) of the mucociliary Xenopus epidermis. Overall, this work describes the first clinically-defined KIF6 homozygous null mutation in human and defines KIF6 as a conserved mediator of neurological development with a specific role for EC ciliogenesis in vertebrates. Cerebrospinal fluid flow is crucial for neurodevelopment and homeostasis of the ventricular system of the brain. Localized flows of cerebrospinal fluid throughout the ventricular system of the brain are established from the polarized beating of the ependymal cell (EC) cilia. Here, we identified a homozygous truncating mutation in KIF6 in a child displaying neurodevelopmental defects and intellectual disability. To test the function of KIF6 in vivo, we engineered mutations of Kif6 in mouse. These Kif6 mutant mice display severe hydrocephalus, coupled with defects in the formation of EC cilia. Similarly, we observed hydrocephalus and a reduction in EC cilia in kif6 mutant zebrafish. Overall, this work describes the first clinically-defined KIF6 mutation in human, while our animal studies demonstrate the pathogenicity of mutations in KIF6 and establish KIF6 as a conserved mediator of ciliogenesis in ECs in vertebrates.
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Affiliation(s)
- Mia J. Konjikusic
- Department of Pediatrics, Dell Pediatric Research Institute, The University of Texas at Austin, Dell Medical School, Austin, Texas, United States of America
- Department of Molecular Biosciences, Patterson Labs, The University of Texas at Austin, Austin, Texas, United States of America
| | - Patra Yeetong
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok, Thailand
- Division of Human Genetics, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Curtis W. Boswell
- Program in Developmental & Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Molecular Genetics, The University of Toronto, Toronto, Ontario, Canada
| | - Chanjae Lee
- Department of Molecular Biosciences, Patterson Labs, The University of Texas at Austin, Austin, Texas, United States of America
| | - Elle C. Roberson
- Department of Molecular Biosciences, Patterson Labs, The University of Texas at Austin, Austin, Texas, United States of America
| | - Rungnapa Ittiwut
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok, Thailand
| | - Kanya Suphapeetiporn
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok, Thailand
| | - Brian Ciruna
- Program in Developmental & Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Molecular Genetics, The University of Toronto, Toronto, Ontario, Canada
| | - Christina A. Gurnett
- Department of Neurology, Division Pediatric Neurology, Washington University School of Medicine, St Louis, MO, United States of America
| | - John B. Wallingford
- Department of Molecular Biosciences, Patterson Labs, The University of Texas at Austin, Austin, Texas, United States of America
| | - Vorasuk Shotelersuk
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok, Thailand
- * E-mail: (VS); (RSG)
| | - Ryan S. Gray
- Department of Pediatrics, Dell Pediatric Research Institute, The University of Texas at Austin, Dell Medical School, Austin, Texas, United States of America
- * E-mail: (VS); (RSG)
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16
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Lewis TR, Kundinger SR, Link BA, Insinna C, Besharse JC. Kif17 phosphorylation regulates photoreceptor outer segment turnover. BMC Cell Biol 2018; 19:25. [PMID: 30458707 PMCID: PMC6245759 DOI: 10.1186/s12860-018-0177-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 11/07/2018] [Indexed: 12/02/2022] Open
Abstract
Background KIF17, a kinesin-2 motor that functions in intraflagellar transport, can regulate the onset of photoreceptor outer segment development. However, the function of KIF17 in a mature photoreceptor remains unclear. Additionally, the ciliary localization of KIF17 is regulated by a C-terminal consensus sequence (KRKK) that is immediately adjacent to a conserved residue (mouse S1029/zebrafish S815) previously shown to be phosphorylated by CaMKII. Yet, whether this phosphorylation can regulate the localization, and thus function, of KIF17 in ciliary photoreceptors remains unknown. Results Using transgenic expression in zebrafish photoreceptors, we show that phospho-mimetic KIF17 has enhanced localization along the cone outer segment. Importantly, expression of phospho-mimetic KIF17 is associated with greatly enhanced turnover of the photoreceptor outer segment through disc shedding in a cell-autonomous manner, while genetic mutants of kif17 in zebrafish and mice have diminished disc shedding. Lastly, cone expression of constitutively active tCaMKII leads to a kif17-dependent increase in disc shedding. Conclusions Taken together, our data support a model in which phosphorylation of KIF17 promotes its photoreceptor outer segment localization and disc shedding, a process essential for photoreceptor maintenance and homeostasis. While disc shedding has been predominantly studied in the context of the mechanisms underlying phagocytosis of outer segments by the retinal pigment epithelium, this work implicates photoreceptor-derived signaling in the underlying mechanisms of disc shedding. Electronic supplementary material The online version of this article (10.1186/s12860-018-0177-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tylor R Lewis
- Department of Cell Biology, Neurobiology, and Anatomy Medical College of Wisconsin, Milwaukee, WI, USA
| | - Sean R Kundinger
- Department of Ophthalmology and Visual Sciences Medical College of Wisconsin, Milwaukee, WI, USA
| | - Brian A Link
- Department of Cell Biology, Neurobiology, and Anatomy Medical College of Wisconsin, Milwaukee, WI, USA
| | - Christine Insinna
- Department of Cell Biology, Neurobiology, and Anatomy Medical College of Wisconsin, Milwaukee, WI, USA.,Laboratory of Cell and Developmental Signaling National Cancer Institute-Frederick, Frederick, MD, USA
| | - Joseph C Besharse
- Department of Cell Biology, Neurobiology, and Anatomy Medical College of Wisconsin, Milwaukee, WI, USA. .,Department of Ophthalmology and Visual Sciences Medical College of Wisconsin, Milwaukee, WI, USA.
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17
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Louka P, Vasudevan KK, Guha M, Joachimiak E, Wloga D, Tomasi RFX, Baroud CN, Dupuis-Williams P, Galati DF, Pearson CG, Rice LM, Moresco JJ, Yates JR, Jiang YY, Lechtreck K, Dentler W, Gaertig J. Proteins that control the geometry of microtubules at the ends of cilia. J Cell Biol 2018; 217:4298-4313. [PMID: 30217954 PMCID: PMC6279374 DOI: 10.1083/jcb.201804141] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/25/2018] [Accepted: 08/31/2018] [Indexed: 11/22/2022] Open
Abstract
Louka et al. describe three conserved proteins that regulate the positions of microtubule ends near the tips of cilia. Mutations in two of these proteins cause a brain malformation, Joubert syndrome. Thus, microtubule ends in cilia may play a role in the pathology of Joubert syndrome. Cilia, essential motile and sensory organelles, have several compartments: the basal body, transition zone, and the middle and distal axoneme segments. The distal segment accommodates key functions, including cilium assembly and sensory activities. While the middle segment contains doublet microtubules (incomplete B-tubules fused to complete A-tubules), the distal segment contains only A-tubule extensions, and its existence requires coordination of microtubule length at the nanometer scale. We show that three conserved proteins, two of which are mutated in the ciliopathy Joubert syndrome, determine the geometry of the distal segment, by controlling the positions of specific microtubule ends. FAP256/CEP104 promotes A-tubule elongation. CHE-12/Crescerin and ARMC9 act as positive and negative regulators of B-tubule length, respectively. We show that defects in the distal segment dimensions are associated with motile and sensory deficiencies of cilia. Our observations suggest that abnormalities in distal segment organization cause a subset of Joubert syndrome cases.
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Affiliation(s)
- Panagiota Louka
- Department of Cellular Biology, University of Georgia, Athens, GA
| | | | - Mayukh Guha
- Department of Cellular Biology, University of Georgia, Athens, GA
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Raphaël F-X Tomasi
- Department of Mechanics, LadHyX, Ecole Polytechnique-Centre National de la Recherche Scientifique, Palaiseau, France
| | - Charles N Baroud
- Department of Mechanics, LadHyX, Ecole Polytechnique-Centre National de la Recherche Scientifique, Palaiseau, France
| | - Pascale Dupuis-Williams
- UMR-S1174 Institut National de la Santé et de la Recherche Médicale, Université Paris-Sud, Bat 443, Orsay, France.,École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris, Paris, France
| | - Domenico F Galati
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Chad G Pearson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Luke M Rice
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX
| | - James J Moresco
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA
| | - Yu-Yang Jiang
- Department of Cellular Biology, University of Georgia, Athens, GA
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA
| | - William Dentler
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, GA
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18
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Cilium structure, assembly, and disassembly regulated by the cytoskeleton. Biochem J 2018; 475:2329-2353. [PMID: 30064990 PMCID: PMC6068341 DOI: 10.1042/bcj20170453] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 07/02/2018] [Accepted: 07/04/2018] [Indexed: 12/17/2022]
Abstract
The cilium, once considered a vestigial structure, is a conserved, microtubule-based organelle critical for transducing extracellular chemical and mechanical signals that control cell polarity, differentiation, and proliferation. The cilium undergoes cycles of assembly and disassembly that are controlled by complex inter-relationships with the cytoskeleton. Microtubules form the core of the cilium, the axoneme, and are regulated by post-translational modifications, associated proteins, and microtubule dynamics. Although actin and septin cytoskeletons are not major components of the axoneme, they also regulate cilium organization and assembly state. Here, we discuss recent advances on how these different cytoskeletal systems affect cilium function, structure, and organization.
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19
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Moye AR, Singh R, Kimler VA, Dilan TL, Munezero D, Saravanan T, Goldberg AFX, Ramamurthy V. ARL2BP, a protein linked to retinitis pigmentosa, is needed for normal photoreceptor cilia doublets and outer segment structure. Mol Biol Cell 2018; 29:1590-1598. [PMID: 29718757 PMCID: PMC6080659 DOI: 10.1091/mbc.e18-01-0040] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The outer segment (OS) of photoreceptor cells is an elaboration of a primary cilium with organized stacks of membranous disks that contain the proteins needed for phototransduction and vision. Though ciliary formation and function has been well characterized, little is known about the role of cilia in the development of photoreceptor OS. Nevertheless, progress has been made by studying mutations in ciliary proteins, which often result in malformed OSs and lead to blinding diseases. To investigate how ciliary proteins contribute to OS formation, we generated a knockout (KO) mouse model for ARL2BP, a ciliary protein linked to retinitis pigmentosa. The KO mice display an early and progressive reduction in visual response. Before photoreceptor degeneration, we observed disorganization of the photoreceptor OS, with vertically aligned disks and shortened axonemes. Interestingly, ciliary doublet microtubule (MT) structure was also impaired, displaying open B-tubule doublets, paired with loss of singlet MTs. On the basis of results from this study, we conclude that ARL2BP is necessary for photoreceptor ciliary doublet formation and axoneme elongation, which is required for OS morphogenesis and vision.
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Affiliation(s)
- Abigail R Moye
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Ratnesh Singh
- Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | | | - Tanya L Dilan
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Daniella Munezero
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | | | | | - Visvanathan Ramamurthy
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506.,Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV 26506
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20
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Nakayama K, Katoh Y. Ciliary protein trafficking mediated by IFT and BBSome complexes with the aid of kinesin-2 and dynein-2 motors. J Biochem 2017; 163:155-164. [DOI: 10.1093/jb/mvx087] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 06/20/2017] [Indexed: 12/21/2022] Open
Affiliation(s)
- Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yohei Katoh
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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21
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Luo W, Ruba A, Takao D, Zweifel LP, Lim RYH, Verhey KJ, Yang W. Axonemal Lumen Dominates Cytosolic Protein Diffusion inside the Primary Cilium. Sci Rep 2017; 7:15793. [PMID: 29150645 PMCID: PMC5693955 DOI: 10.1038/s41598-017-16103-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 11/03/2017] [Indexed: 12/02/2022] Open
Abstract
Transport of membrane and cytosolic proteins in primary cilia is thought to depend on intraflagellar transport (IFT) and diffusion. However, the relative contribution and spatial routes of each transport mechanism are largely unknown. Although challenging to decipher, the details of these routes are essential for our understanding of protein transport in primary cilia, a critically affected process in many genetic diseases. By using a high-speed virtual 3D super-resolution microscopy, we have mapped the 3D spatial locations of transport routes for various cytosolic proteins in the 250-nm-wide shaft of live primary cilia with a spatiotemporal resolution of 2 ms and <16 nm. Our data reveal two spatially distinguishable transport routes for cytosolic proteins: an IFT-dependent path along the axoneme, and a passive-diffusion route in the axonemal lumen that escaped previous studies. While all cytosolic proteins tested primarily utilize the IFT path in the anterograde direction, differences are observed in the retrograde direction where IFT20 only utilizes IFT, and approximately half of KIF17 and one third of α–tubulin utilizes diffusion besides IFT.
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Affiliation(s)
- Wangxi Luo
- Department of Biology, Temple University, Philadelphia, Pennsylvania, 19122, USA
| | - Andrew Ruba
- Department of Biology, Temple University, Philadelphia, Pennsylvania, 19122, USA
| | - Daisuke Takao
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Ludovit P Zweifel
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel, Switzerland
| | - Roderick Y H Lim
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel, Switzerland
| | - Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Weidong Yang
- Department of Biology, Temple University, Philadelphia, Pennsylvania, 19122, USA.
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22
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Feng D, Chen Z, Yang K, Miao S, Xu B, Kang Y, Xie H, Zhao C. The cytoplasmic tail of rhodopsin triggers rapid rod degeneration in kinesin-2 mutants. J Biol Chem 2017; 292:17375-17386. [PMID: 28855254 DOI: 10.1074/jbc.m117.784017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 08/24/2017] [Indexed: 11/06/2022] Open
Abstract
Photoreceptor degeneration can lead to blindness and represents the most common form of neural degenerative disease worldwide. Although many genes involved in photoreceptor degeneration have been identified, the underlying mechanisms remain to be elucidated. Here we examined photoreceptor development in zebrafish kif3a and kif3b mutants, which affect two subunits of the kinesin-2 complex. In both mutants, rods degenerated quickly, whereas cones underwent a slow degeneration process. Notably, the photoreceptor defects were considerably more severe in kif3a mutants than in kif3b mutants. In the cone photoreceptors of kif3a mutants, opsin proteins accumulated in the apical region and formed abnormal membrane structures. In contrast, rhodopsins were enriched in the rod cell body membrane and represented the primary reason for rapid rod degeneration in these mutants. Moreover, removal of the cytoplasmic tail of rhodopsin to reduce its function, but not decreasing rhodopsin expression levels, prevented rod degeneration in both kif3a and kif3b mutants. Of note, overexpression of full-length rhodopsin or its cytoplasmic tail domain, but not of rhodopsin lacking the cytoplasmic tail, exacerbated rod degeneration in kif3a mutants, implying an important role of the cytoplasmic tail in rod degeneration. Finally, we showed that the cytoplasmic tail of rhodopsin might trigger rod degeneration through activating the downstream calcium signaling pathway, as drug treatment with inhibitors of intracellular calcium release prevented rod degeneration in kif3a mutants. Our results demonstrate a previously unknown function of the rhodopsin cytoplasmic domain during opsin-triggered photoreceptor degeneration and may open up new avenues for managing this disease.
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Affiliation(s)
- Dong Feng
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Zhe Chen
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Kuang Yang
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Shanshan Miao
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Bolin Xu
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Yunsi Kang
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Haibo Xie
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Chengtian Zhao
- From the Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China, .,the Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China, and.,the Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
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23
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Intraflagellar transport velocity is governed by the number of active KIF17 and KIF3AB motors and their motility properties under load. Proc Natl Acad Sci U S A 2017; 114:E6830-E6838. [PMID: 28761002 DOI: 10.1073/pnas.1708157114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Homodimeric KIF17 and heterotrimeric KIF3AB are processive, kinesin-2 family motors that act jointly to carry out anterograde intraflagellar transport (IFT), ferrying cargo along microtubules (MTs) toward the tips of cilia. How IFT trains attain speeds that exceed the unloaded rate of the slower, KIF3AB motor remains unknown. By characterizing the motility properties of kinesin-2 motors as a function of load we find that the increase in KIF3AB velocity, elicited by forward loads from KIF17 motors, cannot alone account for the speed of IFT trains in vivo. Instead, higher IFT velocities arise from an increased likelihood that KIF3AB motors dissociate from the MT, resulting in transport by KIF17 motors alone, unencumbered by opposition from KIF3AB. The rate of transport is therefore set by an equilibrium between a faster state, where only KIF17 motors move the train, and a slower state, where at least one KIF3AB motor on the train remains active in transport. The more frequently the faster state is accessed, the higher the overall velocity of the IFT train. We conclude that IFT velocity is governed by (i) the absolute numbers of each motor type on a given train, (ii) how prone KIF3AB is to dissociation from MTs relative to KIF17, and (iii) how prone both motors are to dissociation relative to binding MTs.
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24
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Schwarz N, Lane A, Jovanovic K, Parfitt DA, Aguila M, Thompson CL, da Cruz L, Coffey PJ, Chapple JP, Hardcastle AJ, Cheetham ME. Arl3 and RP2 regulate the trafficking of ciliary tip kinesins. Hum Mol Genet 2017; 26:2480-2492. [PMID: 28444310 PMCID: PMC5808637 DOI: 10.1093/hmg/ddx143] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/07/2017] [Accepted: 04/11/2017] [Indexed: 11/14/2022] Open
Abstract
Ciliary trafficking defects are the underlying cause of many ciliopathies, including Retinitis Pigmentosa (RP). Anterograde intraflagellar transport (IFT) is mediated by kinesin motor proteins; however, the function of the homodimeric Kif17 motor in cilia is poorly understood, whereas Kif7 is known to play an important role in stabilizing cilia tips. Here we identified the ciliary tip kinesins Kif7 and Kif17 as novel interaction partners of the small GTPase Arl3 and its regulatory GTPase activating protein (GAP) Retinitis Pigmentosa 2 (RP2). We show that Arl3 and RP2 mediate the localization of GFP-Kif17 to the cilia tip and competitive binding of RP2 and Arl3 with Kif17 complexes. RP2 and Arl3 also interact with another ciliary tip kinesin, Kif7, which is a conserved regulator of Hedgehog (Hh) signaling. siRNA-mediated loss of RP2 or Arl3 reduced the level of Kif7 at the cilia tip. This was further validated by reduced levels of Kif7 at cilia tips detected in fibroblasts and induced pluripotent stem cell (iPSC) 3D optic cups derived from a patient carrying an RP2 nonsense mutation c.519C > T (p.R120X), which lack detectable RP2 protein. Translational read-through inducing drugs (TRIDs), such as PTC124, were able to restore Kif7 levels at the ciliary tip of RP2 null cells. Collectively, our findings suggest that RP2 and Arl3 regulate the trafficking of specific kinesins to cilia tips and provide additional evidence that TRIDs could be clinically beneficial for patients with this retinal degeneration.
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Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - Amelia Lane
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | | | | | | | - Clare L. Thompson
- Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | - Lyndon da Cruz
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Moorfields Eye Hospital, London EC1V 2PD, UK
| | | | - J. Paul Chapple
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
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25
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Hsu KS, Chuang JZ, Sung CH. The Biology of Ciliary Dynamics. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a027904. [PMID: 28062565 DOI: 10.1101/cshperspect.a027904] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The cilium is an evolutionally conserved apical membrane protrusion that senses and transduces diverse signals to regulate a wide range of cellular activities. The cilium is dynamic in length, structure, and protein composition. Dysregulation of ciliary dynamics has been linked with ciliopathies and other human diseases. The cilium undergoes cell-cycle-dependent assembly and disassembly, with ciliary resorption linked with G1-S transition and cell-fate choice. In the resting cell, the cilium remains sensitive to environmental cues for remodeling during tissue homeostasis and repair. Recent findings further reveal an interplay between the cilium and extracellular vesicles and identify bioactive cilium-derived vesicles, posing a previously unrecognized role of cilia for sending signals. The photoreceptor outer segment is a notable dynamic cilium. A recently discovered protein transport mechanism in photoreceptors maintains light-regulated homeostasis of ciliary length.
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Affiliation(s)
- Kuo-Shun Hsu
- The Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, New York 10065
| | - Jen-Zen Chuang
- The Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, New York 10065
| | - Ching-Hwa Sung
- Departments of Cell and Developmental Biology, Weill Cornell Medical College, New York, New York 10065
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26
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Lewis TR, Kundinger SR, Pavlovich AL, Bostrom JR, Link BA, Besharse JC. Cos2/Kif7 and Osm-3/Kif17 regulate onset of outer segment development in zebrafish photoreceptors through distinct mechanisms. Dev Biol 2017; 425:176-190. [PMID: 28341548 PMCID: PMC5558849 DOI: 10.1016/j.ydbio.2017.03.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 03/20/2017] [Accepted: 03/20/2017] [Indexed: 12/19/2022]
Abstract
Zebrafish morphants of osm-3/kif17, a kinesin-2 family member and intraflagellar transport motor, have photoreceptor outer segments that are dramatically reduced in number and size. However, two genetic mutant lines, osm-3/kif17sa0119 and osm-3/kif17sa18340, reportedly lack any observable morphological outer segment defects. In this work, we use TALENs to generate an independent allele, osm-3/kif17mw405, and show that both osm-3/kif17sa0119 and osm-3/kif17mw405 have an outer segment developmental delay in both size and density that is fully recovered by 6 days post-fertilization. Additionally, we use CRISPRs to generate cos2/kif7mw406, a mutation in the kinesin-4 family member cos2/kif7 that has been implicated in controlling ciliary architecture and Hedgehog signaling to test whether it may be functioning redundantly with osm-3/kif17. We show that cos2/kif7mw406 has an outer segment developmental delay similar to the osm-3/kif17 mutants. Using a three-dimensional mathematical model of outer segments, we show that while cos2/kif7mw406 and osm-3/kif17mw405 outer segments are smaller throughout the first 6 days of development, the volumetric rates of outer segment morphogenesis are not different among wild-type, cos2/kif7mw406, and osm-3/kif17mw405 after 60hpf. Instead, our model suggests that cos2/kif7mw406 and osm-3/kif17mw405 impact outer segment morphogenesis through upstream events that that are different for each motor. In the case of cos2/kif7mw406 mutants, we show that early defects in Hedgehog signaling lead to a general, non-photoreceptor-specific delay of retinal neurogenesis, which in turn causes the secondary phenotype of delayed outer segment morphogenesis. In contrast, the osm-3/kif17mw405 outer segment morphogenesis delays are linked specifically to initial disc morphogenesis of photoreceptors rather than an upstream event. Further, we show that osm-3/kif17 mutant mice also exhibit a similarly delayed outer segment development, suggesting a role for osm-3/kif17 in early outer segment development that is conserved across species. In conclusion, we show that both osm-3/kif17 and cos2/kif7 have comparable outer segment developmental delays, although through independent mechanisms.
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Affiliation(s)
- Tylor R Lewis
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sean R Kundinger
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Amira L Pavlovich
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jonathan R Bostrom
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Brian A Link
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Joseph C Besharse
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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Goetz SC, Bangs F, Barrington CL, Katsanis N, Anderson KV. The Meckel syndrome- associated protein MKS1 functionally interacts with components of the BBSome and IFT complexes to mediate ciliary trafficking and hedgehog signaling. PLoS One 2017; 12:e0173399. [PMID: 28291807 PMCID: PMC5349470 DOI: 10.1371/journal.pone.0173399] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/20/2017] [Indexed: 12/04/2022] Open
Abstract
The importance of primary cilia in human health is underscored by the link between ciliary dysfunction and a group of primarily recessive genetic disorders with overlapping clinical features, now known as ciliopathies. Many of the proteins encoded by ciliopathy-associated genes are components of a handful of multi-protein complexes important for the transport of cargo to the basal body and/or into the cilium. A key question is whether different complexes cooperate in cilia formation, and whether they participate in cilium assembly in conjunction with intraflagellar transport (IFT) proteins. To examine how ciliopathy protein complexes might function together, we have analyzed double mutants of an allele of the Meckel syndrome (MKS) complex protein MKS1 and the BBSome protein BBS4. We find that Mks1; Bbs4 double mutant mouse embryos exhibit exacerbated defects in Hedgehog (Hh) dependent patterning compared to either single mutant, and die by E14.5. Cells from double mutant embryos exhibit a defect in the trafficking of ARL13B, a ciliary membrane protein, resulting in disrupted ciliary structure and signaling. We also examined the relationship between the MKS complex and IFT proteins by analyzing double mutant between Mks1 and a hypomorphic allele of the IFTB component Ift172. Despite each single mutant surviving until around birth, Mks1; Ift172avc1 double mutants die at mid-gestation, and exhibit a dramatic failure of cilia formation. We also find that Mks1 interacts genetically with an allele of Dync2h1, the IFT retrograde motor. Thus, we have demonstrated that the MKS transition zone complex cooperates with the BBSome to mediate trafficking of specific trans-membrane receptors to the cilium. Moreover, the genetic interaction of Mks1 with components of IFT machinery suggests that the transition zone complex facilitates IFT to promote cilium assembly and structure.
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Affiliation(s)
- Sarah C. Goetz
- Program in Developmental Biology, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Ave. New York, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, United States of America
| | - Fiona Bangs
- Program in Developmental Biology, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Ave. New York, United States of America
| | - Chloe L. Barrington
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, United States of America
| | - Nicholas Katsanis
- Department of Cell Biology and Center for Human Disease Modeling, Duke University Medical Center, Durham, NC, United States of America
| | - Kathryn V. Anderson
- Program in Developmental Biology, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Ave. New York, United States of America
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28
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Funabashi T, Katoh Y, Michisaka S, Terada M, Sugawa M, Nakayama K. Ciliary entry of KIF17 is dependent on its binding to the IFT-B complex via IFT46-IFT56 as well as on its nuclear localization signal. Mol Biol Cell 2017; 28:624-633. [PMID: 28077622 PMCID: PMC5328621 DOI: 10.1091/mbc.e16-09-0648] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 12/27/2016] [Accepted: 01/03/2017] [Indexed: 12/21/2022] Open
Abstract
Cilia function as cellular antennae to sense and transduce extracellular signals. A number of proteins are specifically localized in cilia. Anterograde and retrograde ciliary protein trafficking are mediated by the IFT-B and IFT-A complexes in concert with kinesin-2 and dynein-2 motors, respectively. However, the role of KIF17, a homodimeric kinesin-2 protein, in protein trafficking has not been fully understood in vertebrate cilia. In this study, we demonstrated, by using the visible immunoprecipitation assay, that KIF17 interacts with the IFT46-IFT56 dimer in the IFT-B complex through its C-terminal sequence located immediately upstream of the nuclear localization signal (NLS). We then showed that KIF17 reaches the ciliary tip independently of its motor domain and requires IFT-B binding for its entry into cilia rather than for its intraciliary trafficking. We further showed that KIF17 ciliary entry depends not only on its binding to IFT-B but also on its NLS, to which importin α proteins bind. Taking the results together, we conclude that in mammalian cells, KIF17 is dispensable for ciliogenesis and IFT-B trafficking but requires IFT-B, as well as its NLS, for its ciliary entry across the permeability barrier located at the ciliary base.
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Affiliation(s)
- Teruki Funabashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Yohei Katoh
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Saki Michisaka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Masaya Terada
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Maho Sugawa
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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He M, Agbu S, Anderson KV. Microtubule Motors Drive Hedgehog Signaling in Primary Cilia. Trends Cell Biol 2017; 27:110-125. [PMID: 27765513 PMCID: PMC5258846 DOI: 10.1016/j.tcb.2016.09.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 09/08/2016] [Accepted: 09/23/2016] [Indexed: 01/05/2023]
Abstract
The mammalian Hedgehog (Hh) signaling pathway is required for development and for maintenance of adult stem cells, and overactivation of the pathway can cause tumorigenesis. All responses to Hh family ligands in mammals require the primary cilium, an ancient microtubule-based organelle that extends from the cell surface. Genetic studies in mice and humans have defined specific functions for cilium-associated microtubule motor proteins: they act in the construction and disassembly of the primary cilium, they control ciliary length and stability, and some have direct roles in mammalian Hh signal transduction. These studies highlight how integrated genetic and cell biological studies can define the molecular mechanisms that underlie cilium-associated health and disease.
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Affiliation(s)
- Mu He
- Department of Physiology and Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Stephanie Agbu
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Biochemistry, Cell, and Molecular Biology Program, Weill Graduate School of Medical Sciences of Cornell University, 1300 York Avenue, New York, NY 10065, USA
| | - Kathryn V Anderson
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
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Torrado B, Graña M, Badano JL, Irigoín F. Ciliary Entry of the Hedgehog Transcriptional Activator Gli2 Is Mediated by the Nuclear Import Machinery but Differs from Nuclear Transport in Being Imp-α/β1-Independent. PLoS One 2016; 11:e0162033. [PMID: 27579771 PMCID: PMC5007031 DOI: 10.1371/journal.pone.0162033] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 08/16/2016] [Indexed: 01/20/2023] Open
Abstract
Gli2 is the primary transcriptional activator of Hedgehog signalling in mammals. Upon stimulation of the pathway, Gli2 moves into the cilium before reaching the nucleus. However, the mechanisms underlying its entry into the cilium are not completely understood. Since several similarities have been reported between nuclear and ciliary import, we investigated if the nuclear import machinery participates in Gli2 ciliary entry. Here we show that while two conserved classical nuclear localization signals mediate Gli2 nuclear localization via importin (Imp)-α/β1, these sequences are not required for Gli2 ciliary import. However, blocking Imp-mediated transport through overexpression of GTP-locked Ran reduced the percentage of Gli2 positive cilia, an effect that was not explained by increased CRM1-dependent export of Gli2 from the cilium. We explored the participation of Imp-β2 in Gli2 ciliary traffic and observed that this transporter is involved in moving Gli2 into the cilium, as has been described for other ciliary proteins. In addition, our data indicate that Imp-β2 might also collaborate in Gli2 nuclear entry. How does Imp-β2 determine the final destination of a protein that can localize to two distinct subcellular compartments remains an open question. Therefore, our data shows that the nuclear-cytoplasmic shuttling machinery plays a critical role mediating the subcellular distribution of Gli2 and the activation of the pathway, but distinct importins likely play a differential role mediating its ciliary and nuclear translocation.
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Affiliation(s)
- Belén Torrado
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
| | - Martín Graña
- Bioinformatics Unit, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
| | - José L. Badano
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
| | - Florencia Irigoín
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, Montevideo CP11800, Uruguay
- * E-mail:
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31
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Raghupathy RK, Zhang X, Alhasani RH, Zhou X, Mullin M, Reilly J, Li W, Liu M, Shu X. Abnormal photoreceptor outer segment development and early retinal degeneration in kif3a mutant zebrafish. Cell Biochem Funct 2016; 34:429-40. [PMID: 27470972 DOI: 10.1002/cbf.3205] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 06/29/2016] [Accepted: 06/30/2016] [Indexed: 01/09/2023]
Abstract
Photoreceptors are highly specialized sensory neurons that possess a modified primary cilium called the outer segment. Photoreceptor outer segment formation and maintenance require highly active protein transport via a process known as intraflagellar transport. Anterograde transport in outer segments is powered by the heterotrimeric kinesin II and coordinated by intraflagellar transport proteins. Here, we describe a new zebrafish model carrying a nonsense mutation in the kinesin II family member 3A (kif3a) gene. Kif3a mutant zebrafish exhibited curved body axes and kidney cysts. Outer segments were not formed in most parts of the mutant retina, and rhodopsin was mislocalized, suggesting KIF3A has a role in rhodopsin trafficking. Both rod and cone photoreceptors degenerated rapidly between 4 and 9 days post fertilization, and electroretinography response was not detected in 7 days post fertilization mutant larvae. Loss of KIF3A in zebrafish also resulted in an intracellular transport defect affecting anterograde but not retrograde transport of organelles. Our results indicate KIF3A plays a conserved role in photoreceptor outer segment formation and intracellular transport.
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Affiliation(s)
| | - Xun Zhang
- Department of Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Reem H Alhasani
- Department of Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Xinzhi Zhou
- Department of Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | | | - James Reilly
- Department of Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Wenchang Li
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
| | - Mugen Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xinhua Shu
- Department of Life Sciences, Glasgow Caledonian University, Glasgow, UK
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Leventea E, Hazime K, Zhao C, Malicki J. Analysis of cilia structure and function in zebrafish. Methods Cell Biol 2016; 133:179-227. [PMID: 27263414 DOI: 10.1016/bs.mcb.2016.04.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cilia are microtubule-based protrusions on the surface of most eukaryotic cells. They are found in most, if not all, vertebrate organs. Prominent cilia form in sensory structures, the eye, the ear, and the nose, where they are crucial for the detection of environmental stimuli, such as light and odors. Cilia are also involved in developmental processes, including left-right asymmetry formation, limb morphogenesis, and the patterning of neurons in the neural tube. Some cilia, such as those found in nephric ducts, are thought to have mechanosensory roles. Zebrafish proved very useful in genetic analysis and imaging of cilia-related processes, and in the modeling of mechanisms behind human cilia abnormalities, known as ciliopathies. A number of zebrafish defects resemble those seen in human ciliopathies. Forward and reverse genetic strategies generated a wide range of cilia mutants in zebrafish, which can be studied using sophisticated genetic and imaging approaches. In this chapter, we provide a set of protocols to examine cilia morphology, motility, and cilia-related defects in a variety of organs, focusing on the embryo and early postembryonic development.
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Affiliation(s)
- E Leventea
- The University of Sheffield, Sheffield, United Kingdom
| | - K Hazime
- The University of Sheffield, Sheffield, United Kingdom
| | - C Zhao
- The University of Sheffield, Sheffield, United Kingdom; Ocean University of China, Qingdao, China
| | - J Malicki
- The University of Sheffield, Sheffield, United Kingdom
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Unexpected Roles for Ciliary Kinesins and Intraflagellar Transport Proteins. Genetics 2016; 203:771-85. [PMID: 27038111 DOI: 10.1534/genetics.115.180943] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 03/22/2016] [Indexed: 11/18/2022] Open
Abstract
Transport of proteins in the ciliary shaft is driven by microtubule-dependent motors, kinesins. Prior studies suggested that the heterotrimeric ciliary kinesin may be dispensable for certain aspects of transport in specialized cilia of vertebrate photoreceptor cells. To test this possibility further, we analyzed the mutant phenotype of the zebrafish kif3a gene, which encodes the common motor subunit of heterotrimeric ciliary kinesins. Cilia are absent in all organs examined, leading to the conclusion that kif3a is indispensable for ciliogenesis in all cells, including photoreceptors. Unexpectedly, kif3a function precedes ciliogenesis as ciliary basal bodies are mispositioned in mutant photoreceptors. This phenotype is much less pronounced in intraflagellar transport (IFT) mutants and reveals that kif3a has a much broader role than previously assumed. Despite the severity of their basal body phenotype, kif3a mutant photoreceptors survive longer compared to those in IFT mutants, which display much weaker basal body mispositioning. This effect is absent in kif3a;IFT double mutants, indicating that IFT proteins have ciliary transport-independent roles, which add to the severity of their photoreceptor phenotype. kif3a is dispensable for basal body docking in otic vesicle sensory epithelia and, surprisingly, short cilia form in mechanosensory cristae even in the absence of kif3a In contrast to Kif3a, the functions of the Kif3c-related protein, encoded by the kif3c-like (kif3cl) gene, and the homodimeric ciliary kinesin, kif17, are dispensable for photoreceptor morphogenesis. These studies demonstrate unexpected new roles for both ciliary heterotrimeric kinesins and IFT particle genes and clarify the function of kif17, the homodimeric ciliary kinesin gene.
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Masyukova SV, Landis DE, Henke SJ, Williams CL, Pieczynski JN, Roszczynialski KN, Covington JE, Malarkey EB, Yoder BK. A Screen for Modifiers of Cilia Phenotypes Reveals Novel MKS Alleles and Uncovers a Specific Genetic Interaction between osm-3 and nphp-4. PLoS Genet 2016; 12:e1005841. [PMID: 26863025 PMCID: PMC4749664 DOI: 10.1371/journal.pgen.1005841] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 01/12/2016] [Indexed: 12/04/2022] Open
Abstract
Nephronophthisis (NPHP) is a ciliopathy in which genetic modifiers may underlie the variable penetrance of clinical features. To identify modifiers, a screen was conducted on C. elegans nphp-4(tm925) mutants. Mutations in ten loci exacerbating nphp-4(tm925) ciliary defects were obtained. Four loci have been identified, three of which are established ciliopathy genes mks-1, mks-2, and mks-5. The fourth allele (yhw66) is a missense mutation (S316F) in OSM-3, a kinesin required for cilia distal segment assembly. While osm-3(yhw66) mutants alone have no overt cilia phenotype, nphp-4(tm925);osm-3(yhw66) double mutants lack distal segments and are dye-filling (Dyf) and osmotic avoidance (Osm) defective, similar to osm-3(mn357) null mutants. In osm-3(yhw66) mutants anterograde intraflagellar transport (IFT) velocity is reduced. Furthermore, expression of OSM-3(S316F)::GFP reduced IFT velocities in nphp-4(tm925) mutants, but not in wild type animals. In silico analysis indicates the S316F mutation may affect a phosphorylation site. Putative phospho-null OSM-3(S316F) and phospho-mimetic OSM-3(S316D) proteins accumulate at the cilia base and tip respectively. FRAP analysis indicates that the cilia entry rate of OSM-3(S316F) is slower than OSM-3 and that in the presence of OSM-3(S316F), OSM-3 and OSM-3(S316D) rates decrease. In the presence OSM-3::GFP or OSM-3(S316D)::GFP, OSM-3(S316F)::tdTomato redistributes along the cilium and accumulates in the cilia tip. OSM-3(S316F) and OSM-3(S316D) are functional as they restore cilia distal segment formation in osm-3(mn357) null mutants; however, only OSM-3(S316F) rescues the osm-3(mn357) null Dyf phenotype. Despite rescue of cilia length in osm-3(mn357) null mutants, neither OSM-3(S316F) nor OSM-3(S316D) restores ciliary defects in nphp-4(tm925);osm-3(yhw66) double mutants. Thus, these OSM-3 mutations cause NPHP-4 dependent and independent phenotypes. These data indicate that in addition to regulating cilia protein entry or exit, NPHP-4 influences localization and function of a distal ciliary kinesin. Moreover, data suggest human OSM-3 homolog (Kif17) could act as a modifying locus affecting disease penetrance or expressivity in NPHP patients. Nephronophthisis (NPHP) is a genetically heterogeneous ciliopathy that has minimal genotype-phenotype correlation. The cause of this variation is not known, but could result from additional mutations in the patients’ backgrounds capable of modifying the phenotype. To identify candidate NPHP modifying loci, we conducted an enhancer mutagenesis screen using C. elegans nphp-4(tm925) mutants. Mutations in ten loci were obtained that severely exacerbated the cilia defects in the nphp-4(tm925) mutants, but importantly, had minimal defects in the absence of the nphp-4 mutation. Here we identified four of these loci, each encoding a cilia protein. Three mutations are in known ciliopathy genes, mks-1, mks-2 and mks-5. The fourth allele is a missense (S316F) mutation in OSM-3, a kinesin required for distal cilia assembly and is the sole kinesin responsible for intraflagellar transport along the cilia distal segment in C. elegans. The osm-3(yhw66) mutation affects a putative phosphorylation site that is important for OSM-3 localization, movement, and function, largely in an nphp-4 dependent manner. These data establish a genetic interaction between osm-3 and nphp-4 that regulates kinesin activity and localization and raises the possibility that mutations in Kif17, the mammalian homolog of osm-3, may influence the phenotypes in human NPHP patients.
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Affiliation(s)
- Svetlana V. Masyukova
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
| | - Dawn E. Landis
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
| | - Scott J. Henke
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
| | - Corey L. Williams
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Jay N. Pieczynski
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
| | - Kelly N. Roszczynialski
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
| | - Jannese E. Covington
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
| | - Erik B. Malarkey
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
| | - Bradley K. Yoder
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham Medical School, Birmingham, Alabama, United States of America
- * E-mail:
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Acharya BR, Espenel C, Libanje F, Raingeaud J, Morgan J, Jaulin F, Kreitzer G. KIF17 regulates RhoA-dependent actin remodeling at epithelial cell-cell adhesions. J Cell Sci 2016; 129:957-70. [PMID: 26759174 DOI: 10.1242/jcs.173674] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 12/31/2015] [Indexed: 12/18/2022] Open
Abstract
The kinesin KIF17 localizes at microtubule plus-ends where it contributes to regulation of microtubule stabilization and epithelial polarization. We now show that KIF17 localizes at cell-cell adhesions and that KIF17 depletion inhibits accumulation of actin at the apical pole of cells grown in 3D organotypic cultures and alters the distribution of actin and E-cadherin in cells cultured in 2D on solid supports. Overexpression of full-length KIF17 constructs or truncation mutants containing the N-terminal motor domain resulted in accumulation of newly incorporated GFP-actin into junctional actin foci, cleared E-cadherin from cytoplasmic vesicles and stabilized cell-cell adhesions to challenge with calcium depletion. Expression of these KIF17 constructs also increased cellular levels of active RhoA, whereas active RhoA was diminished in KIF17-depleted cells. Inhibition of RhoA or its effector ROCK, or expression of LIMK1 kinase-dead or activated cofilin(S3A) inhibited KIF17-induced junctional actin accumulation. Interestingly, KIF17 activity toward actin depends on the motor domain but is independent of microtubule binding. Together, these data show that KIF17 can modify RhoA-GTPase signaling to influence junctional actin and the stability of the apical junctional complex of epithelial cells.
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Affiliation(s)
- Bipul R Acharya
- Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Cedric Espenel
- Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Fotine Libanje
- Gustave Roussy Institute, UMR-8126, 114 rue Edouard Vaillant, Villejuif 94805, France
| | - Joel Raingeaud
- Gustave Roussy Institute, UMR-8126, 114 rue Edouard Vaillant, Villejuif 94805, France
| | - Jessica Morgan
- Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Fanny Jaulin
- Gustave Roussy Institute, UMR-8126, 114 rue Edouard Vaillant, Villejuif 94805, France
| | - Geri Kreitzer
- Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY, USA
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37
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Falk N, Lösl M, Schröder N, Gießl A. Specialized Cilia in Mammalian Sensory Systems. Cells 2015; 4:500-19. [PMID: 26378583 PMCID: PMC4588048 DOI: 10.3390/cells4030500] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 08/04/2015] [Accepted: 09/09/2015] [Indexed: 02/01/2023] Open
Abstract
Cilia and flagella are highly conserved and important microtubule-based organelles that project from the surface of eukaryotic cells and act as antennae to sense extracellular signals. Moreover, cilia have emerged as key players in numerous physiological, developmental, and sensory processes such as hearing, olfaction, and photoreception. Genetic defects in ciliary proteins responsible for cilia formation, maintenance, or function underlie a wide array of human diseases like deafness, anosmia, and retinal degeneration in sensory systems. Impairment of more than one sensory organ results in numerous syndromic ciliary disorders like the autosomal recessive genetic diseases Bardet-Biedl and Usher syndrome. Here we describe the structure and distinct functional roles of cilia in sensory organs like the inner ear, the olfactory epithelium, and the retina of the mouse. The spectrum of ciliary function in fundamental cellular processes highlights the importance of elucidating ciliopathy-related proteins in order to find novel potential therapies.
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Affiliation(s)
- Nathalie Falk
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, 91058 Erlangen, Germany.
| | - Marlene Lösl
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, 91058 Erlangen, Germany.
| | - Nadja Schröder
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, 91058 Erlangen, Germany.
| | - Andreas Gießl
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, 91058 Erlangen, Germany.
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Choi SY, Baek JI, Zuo X, Kim SH, Dunaief JL, Lipschutz JH. Cdc42 and sec10 Are Required for Normal Retinal Development in Zebrafish. Invest Ophthalmol Vis Sci 2015; 56:3361-70. [PMID: 26024121 DOI: 10.1167/iovs.14-15692] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize the function and mechanisms of cdc42 and sec10 in eye development in zebrafish. METHODS Knockdown of zebrafish cdc42 and sec10 was carried out using antisense morpholino injection. The phenotype of morphants was characterized by histology, immunohistology, and transmission electron microscopy (TEM). To investigate a synergistic genetic interaction between cdc42 and sec10, we titrated suboptimal doses of cdc42 and sec10 morpholinos, and coinjected both morpholinos. To study trafficking, a melanosome transport assay was performed using epinephrine. RESULTS Cdc42 and sec10 knockdown in zebrafish resulted in both abnormal eye development and increased retinal cell death. Cdc42 morphants had a relatively normal retinal structure, aside from the absence of most connecting cilia and outer segments, whereas in sec10 morphants, much of the outer nuclear layer, which is composed of the photoreceptor nuclei, was missing and RPE cell thickness was markedly irregular. Knockdown of cdc42 and sec10 also resulted in an intracellular transport defect affecting retrograde melanosome transport. Furthermore, there was a synergistic genetic interaction between zebrafish cdc42 and sec10, suggesting that cdc42 and sec10 act in the same pathway in retinal development. CONCLUSIONS We propose a model whereby sec10 and cdc42 play a central role in development of the outer segment of the retinal photoreceptor cell by trafficking proteins necessary for ciliogenesis.
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Affiliation(s)
- Soo Young Choi
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Jeong-In Baek
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Xiaofeng Zuo
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Seok-Hyung Kim
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Joshua H Lipschutz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States 3Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, United States
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Jiang L, Tam BM, Ying G, Wu S, Hauswirth WW, Frederick JM, Moritz OL, Baehr W. Kinesin family 17 (osmotic avoidance abnormal-3) is dispensable for photoreceptor morphology and function. FASEB J 2015; 29:4866-80. [PMID: 26229057 DOI: 10.1096/fj.15-275677] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/27/2015] [Indexed: 01/22/2023]
Abstract
In Caenorhabditis elegans, homodimeric [kinesin family (KIF) 17, osmotic avoidance abnormal-3 (OSM-3)] and heterotrimeric (KIF3) kinesin-2 motors are required to establish sensory cilia by intraflagellar transport (IFT) where KIF3 and KIF17 cooperate to build the axoneme core and KIF17 builds the distal segments. However, the function of KIF17 in vertebrates is unresolved. We expressed full-length and motorless KIF17 constructs in mouse rod photoreceptors using adeno-associated virus in Xenopus laevis rod photoreceptors using a transgene and in ciliated IMCD3 cells. We found that tagged KIF17 localized along the rod outer segment axoneme when expressed in mouse and X. laevis photoreceptors, whereas KIF3A was restricted to the proximal axoneme. Motorless KIF3A and KIF17 mutants caused photoreceptor degeneration, likely through dominant negative effects on IFT. KIF17 mutant lacking the motor domain translocated to nuclei after exposure of a C-terminal nuclear localization signal. Germ-line deletion of Kif17 in mouse did not affect photoreceptor function. A rod-specific Kif3/Kif17 double knockout mouse demonstrated that KIF17 and KIF3 do not act synergistically and did not prevent rhodopsin trafficking to rod outer segments. In summary, the nematode model of KIF3/KIF17 cooperation apparently does not apply to mouse photoreceptors in which the photosensory cilium is built exclusively by KIF3.
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Affiliation(s)
- Li Jiang
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Beatrice M Tam
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Guoxing Ying
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Sen Wu
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - William W Hauswirth
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Jeanne M Frederick
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Orson L Moritz
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - Wolfgang Baehr
- *Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, USA; Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China; Department of Ophthalmology, University of Florida College of Medicine, Gainesville, Florida, USA; and Department of Biology, University of Utah, Salt Lake City, Utah, USA
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Leaf A, Von Zastrow M. Dopamine receptors reveal an essential role of IFT-B, KIF17, and Rab23 in delivering specific receptors to primary cilia. eLife 2015; 4. [PMID: 26182404 PMCID: PMC4547097 DOI: 10.7554/elife.06996] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/15/2015] [Indexed: 01/05/2023] Open
Abstract
Appropriate physiological signaling by primary cilia depends on the specific targeting of particular receptors to the ciliary membrane, but how this occurs remains poorly understood. In this study, we show that D1-type dopaminergic receptors are delivered to cilia from the extra-ciliary plasma membrane by a mechanism requiring the receptor cytoplasmic tail, the intraflagellar transport complex-B (IFT-B), and ciliary kinesin KIF17. This targeting mechanism critically depends on Rab23, a small guanine nucleotide binding protein that has important effects on physiological signaling from cilia but was not known previously to be essential for ciliary delivery of any cargo. Depleting Rab23 prevents dopamine receptors from accessing the ciliary membrane. Conversely, fusion of Rab23 to a non-ciliary receptor is sufficient to drive robust, nucleotide-dependent mis-localization to the ciliary membrane. Dopamine receptors thus reveal a previously unrecognized mechanism of ciliary receptor targeting and functional role of Rab23 in promoting this process.
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Affiliation(s)
- Alison Leaf
- Program in Cell Biology, University of California, San Francisco, San Francisco, United States
| | - Mark Von Zastrow
- Program in Cell Biology, University of California, San Francisco, San Francisco, United States
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Rhodopsin Trafficking and Mistrafficking: Signals, Molecular Components, and Mechanisms. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 132:39-71. [PMID: 26055054 DOI: 10.1016/bs.pmbts.2015.02.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rhodopsin is a seven-transmembrane G protein-coupled receptor (GPCR) and is the main component of the photoreceptor outer segment (OS), a ciliary compartment essential for vision. Because the OSs are incapable of protein synthesis, rhodopsin must first be synthesized in the inner segments (ISs) and subsequently trafficked across the connecting cilia to the OSs where it participates in the phototransduction cascade. Rapid turnover of the OS necessitates a high rate of synthesis and efficient trafficking of rhodopsin to the cilia. This cilia-targeting mechanism is shared among other ciliary-localized GPCRs. In this review, we will discuss the process of rhodopsin trafficking from the IS to the OS beginning with the trafficking signals present on the protein. Starting from the endoplasmic reticulum and the Golgi apparatus within the IS, we will cover the molecular components assisting the biogenesis and the proper sorting. We will also review the confirmed binding and interacting partners that help target rhodopsin toward the connecting cilium as well as the cilia-localized components which direct proteins into the proper compartments of the OS. While rhodopsin is the most critical and abundant component of the photoreceptor OS, mutations in the rhodopsin gene commonly lead to its mislocalization within the photoreceptors. In addition to covering the trafficking patterns of rhodopsin, we will also review some of the most common rhodopsin mutants which cause mistrafficking and subsequent death of photoreceptors. Toward the goal of understanding the pathogenesis, three major mechanisms of aberrant trafficking as well as putative mechanisms of photoreceptor degeneration will be discussed.
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42
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Microtubule-depolymerizing kinesins in the regulation of assembly, disassembly, and length of cilia and flagella. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 317:241-65. [PMID: 26008787 DOI: 10.1016/bs.ircmb.2015.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Defects in ciliary assembly, maintenance, and signaling are associated with various human diseases and developmental disorders, termed ciliopathies. Eukaryotic flagella and cilia (interchangeable terms) are microtubule-based organelles. Thus, microtubule dynamics and microtubule-dependent transport are predicted to affect the structural integrity and functionality of cilia profoundly. Kinesin-2 is well known for its role in intraflagellar transport to transport ciliary precursors and signaling molecules. Recently, microtubule-depolymerizing kinesins found in kinesin-8, -13, and -14A families have emerged as regulators of cilia. We first discuss ciliary kinesins identified in the flagellar or ciliary proteome, and then focus on the function and regulation of microtubule-depolymerizing kinesins. Lastly, we review the recent advances of microtubule-depolymerizing kinesins in controlling ciliary assembly, disassembly, and length.
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Early steps in primary cilium assembly require EHD1/EHD3-dependent ciliary vesicle formation. Nat Cell Biol 2015; 17:228-240. [PMID: 25686250 PMCID: PMC4344897 DOI: 10.1038/ncb3109] [Citation(s) in RCA: 170] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 01/13/2015] [Indexed: 12/12/2022]
Abstract
Membrane association with mother centriole (M-centriole) distal appendages is critical for ciliogenesis initiation. How the Rab GTPase Rab11-Rab8 cascade functions in early ciliary membrane assembly is unknown. Here, we show that the membrane shaping proteins EHD1 and EHD3, in association with the Rab11-Rab8 cascade, function in early ciliogenesis. EHD1 and EHD3 localize to pre-ciliary membranes and the ciliary pocket. EHD-dependent membrane tubulation is essential for ciliary vesicle (CV) formation from smaller distal appendage vesicles (DAV). Importantly, this step functions in M-centriole to basal body transformation and recruitment of transition zone proteins and IFT20. SNAP29, a SNARE membrane fusion regulator and EHD1-binding protein, is also required for DAV-mediated CV assembly. Interestingly, only after CV assembly is Rab8 activated for ciliary growth. Our studies uncover molecular mechanisms informing a previously uncharacterized ciliogenesis step whereby EHD1 and EHD3 reorganize the M-centriole and associated DAV prior to coordinated ciliary membrane and axoneme growth.
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Carpenter BS, Barry RL, Verhey KJ, Allen BL. The heterotrimeric kinesin-2 complex interacts with and regulates GLI protein function. J Cell Sci 2015; 128:1034-50. [PMID: 25588831 DOI: 10.1242/jcs.162552] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
GLI transport to the primary cilium and nucleus is required for proper Hedgehog (HH) signaling; however, the mechanisms that mediate these trafficking events are poorly understood. Kinesin-2 motor proteins regulate ciliary transport of cargo, yet their role in GLI protein function remains unexplored. To examine a role for the heterotrimeric KIF3A-KIF3B-KAP3 kinesin-2 motor complex in regulating GLI activity, we performed a series of structure-function analyses using biochemical, cell signaling and in vivo approaches that define novel specific interactions between GLI proteins and two components of this complex, KAP3 and KIF3A. We find that all three mammalian GLI proteins interact with KAP3 and we map specific interaction sites in both proteins. Furthermore, we find that GLI proteins interact selectively with KIF3A, but not KIF3B, and that GLI interacts synergistically with KAP3 and KIF3A. Using a combination of cell signaling assays and chicken in ovo electroporation, we demonstrate that KAP3 interactions restrict GLI activator function but not GLI repressor function. These data suggest that GLI interactions with KIF3A-KIF3B-KAP3 complexes are essential for proper GLI transcriptional activity.
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Affiliation(s)
- Brandon S Carpenter
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Renee L Barry
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Benjamin L Allen
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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Broekhuis JR, Verhey KJ, Jansen G. Regulation of cilium length and intraflagellar transport by the RCK-kinases ICK and MOK in renal epithelial cells. PLoS One 2014; 9:e108470. [PMID: 25243405 PMCID: PMC4171540 DOI: 10.1371/journal.pone.0108470] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/25/2014] [Indexed: 01/11/2023] Open
Abstract
Primary cilia are important sensory organelles. They exist in a wide variety of lengths, which could reflect different cell-specific functions. How cilium length is regulated is unclear, but it probably involves intraflagellar transport (IFT), which transports protein complexes along the ciliary axoneme. Studies in various organisms have identified the small, conserved family of ros-cross hybridizing kinases (RCK) as regulators of cilium length. Here we show that Intestinal Cell Kinase (ICK) and MAPK/MAK/MRK overlapping kinase (MOK), two members of this family, localize to cilia of mouse renal epithelial (IMCD-3) cells and negatively regulate cilium length. To analyze the effects of ICK and MOK on the IFT machinery, we set up live imaging of five fluorescently tagged IFT proteins: KIF3B, a subunit of kinesin-II, the main anterograde IFT motor, complex A protein IFT43, complex B protein IFT20, BBSome protein BBS8 and homodimeric kinesin KIF17, whose function in mammalian cilia is unclear. Interestingly, all five proteins moved at ∼0.45 µm/s in anterograde and retrograde direction, suggesting they are all transported by the same machinery. Moreover, GFP tagged ICK and MOK moved at similar velocities as the IFT proteins, suggesting they are part of, or transported by the IFT machinery. Indeed, loss- or gain-of-function of ICK affected IFT speeds: knockdown increased anterograde velocities, whereas overexpression reduced retrograde speed. In contrast, MOK knockdown or overexpression did not affect IFT speeds. Finally, we found that the effects of ICK or MOK knockdown on cilium length and IFT are suppressed by rapamycin treatment, suggesting that these effects require the mTORC1 pathway. Our results confirm the importance of RCK kinases as regulators of cilium length and IFT. However, whereas some of our results suggest a direct correlation between cilium length and IFT speed, other results indicate that cilium length can be modulated independent of IFT speed.
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Affiliation(s)
| | - Kristen J. Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Gert Jansen
- Department of Cell Biology, Erasmus MC, Rotterdam, the Netherlands
- * E-mail:
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Krock BL, Perkins BD. The Par-PrkC polarity complex is required for cilia growth in zebrafish photoreceptors. PLoS One 2014; 9:e104661. [PMID: 25144710 PMCID: PMC4140697 DOI: 10.1371/journal.pone.0104661] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/13/2014] [Indexed: 01/09/2023] Open
Abstract
Specification and development of the apical membrane in epithelial cells requires the function of polarity proteins, including Pard3 and an atypical protein kinase C (PrkC). Many epithelial cells possess microtubule-based organelles, known as cilia, that project from their apical surface and the membrane surrounding the cilium is contiguous with the apical cell membrane. Although cilia formation in cultured cells required Pard3, the in vivo requirement for Pard3 in cilia development remains unknown. The vertebrate photoreceptor outer segment represents a highly specialized cilia structure in which to identify factors necessary for apical and ciliary membrane formation. Pard3 and PrkC localized to distinct domains within vertebrate photoreceptors. Using partial morpholino knockdown, photo-morpholinos, and pharmacological approaches, the function of Pard3 and PrkC were found to be required for the formation of both the apical and ciliary membrane of vertebrate photoreceptors. Inhibition of Pard3 or PrkC activity significantly reduced the size of photoreceptor outer segments and resulted in mislocalization of rhodopsin. Suppression of Pard3 or PrkC also led to a reduction in cilia size and cilia number in Kupffer's Vesicle, which resulted in left-right asymmetry defects. Thus, the Par-PrkC complex functions in cilia formation in vivo and this likely reflects a general role in specifying non-ciliary and ciliary compartments of the apical domain.
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Affiliation(s)
- Bryan L. Krock
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Brian D. Perkins
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
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He M, Subramanian R, Bangs F, Omelchenko T, Liem KF, Kapoor TM, Anderson KV. The kinesin-4 protein Kif7 regulates mammalian Hedgehog signalling by organizing the cilium tip compartment. Nat Cell Biol 2014; 16:663-72. [PMID: 24952464 PMCID: PMC4085576 DOI: 10.1038/ncb2988] [Citation(s) in RCA: 214] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 05/13/2014] [Indexed: 12/12/2022]
Abstract
Mammalian Hedgehog (Hh) signal transduction requires a primary cilium, a microtubule-based organelle, and the Gli-Sufu complexes that mediate Hh signalling, which are enriched at cilia tips. Kif7, a kinesin-4 family protein, is a conserved regulator of the Hh signalling pathway and a human ciliopathy protein. Here we show that Kif7 localizes to the cilium tip, the site of microtubule plus ends, where it limits cilium length and controls cilium structure. Purified recombinant Kif7 binds the plus ends of growing microtubules in vitro, where it reduces the rate of microtubule growth and increases the frequency of microtubule catastrophe. Kif7 is not required for normal intraflagellar transport or for trafficking of Hh pathway proteins into cilia. Instead, a central function of Kif7 in the mammalian Hh pathway is to control cilium architecture and to create a single cilium tip compartment, where Gli-Sufu activity can be correctly regulated.
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Affiliation(s)
- Mu He
- 1] Developmental Biology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue New York, New York 10065, USA [2] Program in Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, 1300 York Avenue New York, New York 10065, USA
| | - Radhika Subramanian
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue New York, New York 10065, USA
| | - Fiona Bangs
- Developmental Biology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue New York, New York 10065, USA
| | - Tatiana Omelchenko
- Cell Biology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue New York, New York 10065, USA
| | - Karel F Liem
- 1] Developmental Biology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue New York, New York 10065, USA [2]
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue New York, New York 10065, USA
| | - Kathryn V Anderson
- Developmental Biology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue New York, New York 10065, USA
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Wasfy MM, Matsui JI, Miller J, Dowling JE, Perkins BD. myosin 7aa(-/-) mutant zebrafish show mild photoreceptor degeneration and reduced electroretinographic responses. Exp Eye Res 2014; 122:65-76. [PMID: 24698764 DOI: 10.1016/j.exer.2014.03.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 03/18/2014] [Accepted: 03/19/2014] [Indexed: 01/20/2023]
Abstract
Mutations in myosin VIIa (MYO7A) cause Usher Syndrome 1B (USH1B), a disease characterized by the combination of sensorineural hearing loss and visual impairment termed retinitis pigmentosa (RP). Although the shaker-1 mouse model of USH1B exists, only minor defects in the retina have been observed during its lifespan. Previous studies of the zebrafish mariner mutant, which also carries a mutation in myo7aa, revealed balance and hearing defects in the mutants but the retinal phenotype has not been described. We found elevated cell death in the outer nuclear layer (ONL) of myo7aa(-/-) mutants. While myo7aa(-/-) mutants retained visual behaviors in the optokinetic reflex (OKR) assay, electroretinogram (ERG) recordings revealed a significant decrease in both a- and b-wave amplitudes in mutant animals, but not a change in ERG threshold sensitivity. Immunohistochemistry showed mislocalization of rod and blue cone opsins and reduced expression of rod-specific markers in the myo7aa(-/-) ONL, providing further evidence that the photoreceptor degeneration observed represents the initial stages of the RP. Further, constant light exposure resulted in widespread photoreceptor degeneration and the appearance of large holes in the retinal pigment epithelium (RPE). No differences were observed in the retinomotor movements of the photoreceptors or in melanosome migration within the RPE, suggesting that myo7aa(-/-) does not function in these processes in teleosts. These results indicate that the zebrafish myo7aa(-/-) mutant is a useful animal model for the RP seen in humans with USH1B.
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Affiliation(s)
- Meagan M Wasfy
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Jonathan I Matsui
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Jessica Miller
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - John E Dowling
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Brian D Perkins
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
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Wheway G, Parry DA, Johnson CA. The role of primary cilia in the development and disease of the retina. Organogenesis 2014; 10:69-85. [PMID: 24162842 PMCID: PMC4049897 DOI: 10.4161/org.26710] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 02/07/2023] Open
Abstract
The normal development and function of photoreceptors is essential for eye health and visual acuity in vertebrates. Mutations in genes encoding proteins involved in photoreceptor development and function are associated with a suite of inherited retinal dystrophies, often as part of complex multi-organ syndromic conditions. In this review, we focus on the role of the photoreceptor outer segment, a highly modified and specialized primary cilium, in retinal health and disease. We discuss the many defects in the structure and function of the photoreceptor primary cilium that can cause a class of inherited conditions known as ciliopathies, often characterized by retinal dystrophy and degeneration, and highlight the recent insights into disease mechanisms.
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Affiliation(s)
- Gabrielle Wheway
- Section of Ophthalmology and Neurosciences; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
| | - David A Parry
- Section of Genetics; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
| | - Colin A Johnson
- Section of Ophthalmology and Neurosciences; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
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Yammine M, Saade M, Chauvet S, Nguyen C. Spatial gene's (Tbata) implication in neurite outgrowth and dendrite patterning in hippocampal neurons. Mol Cell Neurosci 2013; 59:1-9. [PMID: 24361585 DOI: 10.1016/j.mcn.2013.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 12/04/2013] [Accepted: 12/12/2013] [Indexed: 01/12/2023] Open
Abstract
The unique architecture of neurons requires the establishment and maintenance of polarity, which relies in part on microtubule-based kinesin motor transport to deliver essential cargo into axons and dendrites. In developing neurons, kinesin trafficking is essential for delivering organelles and molecules that are crucial for elongation and guidance of the growing axonal and dendritic termini. In mature neurons, kinesin cargo delivery is essential for neuron dynamic physiological functions which are critical in brain development. In this work, we followed Spatial (Tbata) gene expression during primary hippocampal neuron development and showed that it is highly expressed during dendrite formation. Spatial protein exhibits a somatodendritic distribution and we show that the kinesin motor Kif17, among other dendrite specific kinesins, is crucial for Spatial localization to dendrites of hippocampal neurons. Furthermore, Spatial down regulation in primary hippocampal cells revealed a role for Spatial in maintaining neurons' polarity by ensuring proper neurite outgrowth. This polarity is specified by intrinsic and extracellular signals that allow neurons to determine axon and dendrite fate during development. Neurotrophic factors, such as the Nerve Growth Factor (NGF), are candidate extracellular polarity-regulating cues which are proposed to accelerate neuronal polarization by enhancing dendrite growth. Here, we show that NGF treatment increases Spatial expression in hippocampal neurons. Altogether, these data suggest that Spatial, in response to NGF and through its transport by Kif17, is crucial for neuronal polarization and can be a key regulator of neurite outgrowth.
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Affiliation(s)
- Miriam Yammine
- Aix-Marseille Université, Inserm UMR 1090, TAGC, Campus de Luminy Case 908, 13288 Marseille Cedex 9, France
| | - Murielle Saade
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Cientific de Barcelona, C/Baldiri i Reixac, Barcelona, Spain
| | - Sophie Chauvet
- Aix-Marseille Université, CNRS UMR 7288, IBDM, Campus de Luminy Case 908, 13288 Marseille Cedex 9, France
| | - Catherine Nguyen
- Aix-Marseille Université, Inserm UMR 1090, TAGC, Campus de Luminy Case 908, 13288 Marseille Cedex 9, France.
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