1
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Tingey M, Ruba A, Jiang Z, Yang W. Deciphering vesicle-assisted transport mechanisms in cytoplasm to cilium trafficking. Front Cell Neurosci 2024; 18:1379976. [PMID: 38860265 PMCID: PMC11163138 DOI: 10.3389/fncel.2024.1379976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 05/13/2024] [Indexed: 06/12/2024] Open
Abstract
The cilium, a pivotal organelle crucial for cell signaling and proper cell function, relies on meticulous macromolecular transport from the cytoplasm for its formation and maintenance. While the intraflagellar transport (IFT) pathway has traditionally been the focus of extensive study concerning ciliogenesis and ciliary maintenance, recent research highlights a complementary and alternative mechanism-vesicle-assisted transport (VAT) in cytoplasm to cilium trafficking. Despite its potential significance, the VAT pathway remains largely uncharacterized. This review explores recent studies providing evidence for the dynamics of vesicle-related diffusion and transport within the live primary cilium, employing high-speed super-resolution light microscopy. Additionally, we analyze the spatial distribution of vesicles in the cilium, mainly relying on electron microscopy data. By scrutinizing the VAT pathways that facilitate cargo transport into the cilium, with a specific emphasis on recent advancements and imaging data, our objective is to synthesize a comprehensive model of ciliary transport through the integration of IFT-VAT mechanisms.
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Affiliation(s)
| | | | | | - Weidong Yang
- Department of Biology, Temple University, Philadelphia, PA, United States
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2
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Baur K, Hölzl-Wenig G, Ciccolini F. A flow cytometry-based approach for the study of primary cilia. Methods Cell Biol 2022; 175:17-31. [PMID: 36967140 DOI: 10.1016/bs.mcb.2022.07.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Primary cilia provide a specialized subcellular environment favoring ordered and timely interaction and modification of signaling molecules, necessary for the sensing and transduction of extracellular signals and environmental conditions. Crucial to the understanding of ciliary function is the knowledge of the signaling molecules composing the ciliary compartment. While proteomes of primary cilia have been published recently, the selective isolation of primary cilia from specific cell types and whole tissue still proves difficult, and many laboratories instead resort to the analysis of cultured cells, which may introduce experimental artifacts. Here we present a flow cytometry-based method to isolate and characterize primary cilia from the murine ventricular-subventricular zone. After deciliation, primary cilia are immunolabeled with antibodies against ciliary markers. As an example, we here use a double-staining with acetylated tubulin, which stains the ciliary axoneme, and ciliary membrane protein ADP-ribosylation-like factor 13b (Arl13b); additionally, we triple-labeled primary cilia using the ciliary marker adenylate cyclase 3 (AC3). Besides analysis at the single particle level, fluorescence activated cell sorting (FACS) allows collection of pure preparations of primary cilia suited for subsequent proteomic analyses like mass spectrometry or western blot. As an example of analytical application, we performed triple immunostaining and FACS analysis to reveal cilia heterogeneity. Thus, our cilia isolation method, which can readily be applied to other tissues or cell culture, will facilitate the study of this key cellular organelle and shed light on its role in normal conditions and disease.
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3
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Peng Z, Resnick A, Young YN. Primary cilium: a paradigm for integrating mathematical modeling with experiments and numerical simulations in mechanobiology. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:1215-1237. [PMID: 33757184 PMCID: PMC8552149 DOI: 10.3934/mbe.2021066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Primary cilia are non-motile, solitary (one per cell) microtubule-based organelles that emerge from the mother centriole after cells have exited the mitotic cycle. Identified as a mechanosensing organelle that responds to both mechanical and chemical stimuli, the primary cilium provides a fertile ground for integrative investigations of mathematical modeling, numerical simulations, and experiments. Recent experimental findings revealed considerable complexity to the underlying mechanosensory mechanisms that transmit extracellular stimuli to intracellular signaling many of which include primary cilia. In this invited review, we provide a brief survey of experimental findings on primary cilia and how these results lead to various mathematical models of the mechanics of the primary cilium bent under an external forcing such as a fluid flow or a trap. Mathematical modeling of the primary cilium as a fluid-structure interaction problem highlights the importance of basal anchorage and the anisotropic moduli of the microtubules. As theoretical modeling and numerical simulations progress, along with improved state-of-the-art experiments on primary cilia, we hope that details of ciliary regulated mechano-chemical signaling dynamics in cellular physiology will be understood in the near future.
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Affiliation(s)
- Zhangli Peng
- Department of Bioengineering, University of Illinois at Chicago, 851 S. Morgan St., Chicago, IL 60607, USA
| | - Andrew Resnick
- Department of Physics, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH 44115, USA
| | - Y.-N. Young
- Department of Mathematical Sciences, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA
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4
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Hu J, Harris PC. Regulation of polycystin expression, maturation and trafficking. Cell Signal 2020; 72:109630. [PMID: 32275942 PMCID: PMC7269868 DOI: 10.1016/j.cellsig.2020.109630] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/03/2020] [Accepted: 04/04/2020] [Indexed: 12/26/2022]
Abstract
The major autosomal dominant polycystic kidney disease (ADPKD) genes, PKD1 and PKD2, are wildly expressed at the organ and tissue level. PKD1 encodes polycystin 1 (PC1), a large membrane associated receptor-like protein that can complex with the PKD2 product, PC2. Various cellular locations have been described for both PC1, including the plasma membrane and extracellular vesicles, and PC2, especially the endoplasmic reticulum (ER), but compelling evidence indicates that the primary cilium, a sensory organelle, is the key site for the polycystin complex to prevent PKD. As with other membrane proteins, the ER biogenesis pathway is key to appropriately folding, performing quality control, and exporting fully folded PC1 to the Golgi apparatus. There is a requirement for binding with PC2 and cleavage of PC1 at the GPS for this folding and export to occur. Six different monogenic defects in this pathway lead to cystic disease development, with PC1 apparently particularly sensitive to defects in this general protein processing pathway. Trafficking of membrane proteins, and the polycystins in particular, through the Golgi to the primary cilium have been analyzed in detail, but at this time, there is no clear consensus on a ciliary targeting sequence required to export proteins to the cilium. After transitioning though the trans-Golgi network, polycystin-bearing vesicles are likely sorted to early or recycling endosomes and then transported to the ciliary base, possibly via docking to transition fibers (TF). The membrane-bound polycystin complex then undergoes facilitated trafficking through the transition zone, the diffusion barrier at the base of the cilium, before entering the cilium. Intraflagellar transport (IFT) may be involved in moving the polycystins along the cilia, but data also indicates other mechanisms. The ciliary polycystin complex can be ubiquitinated and removed from cilia by internalization at the ciliary base and may be sent back to the plasma membrane for recycling or to lysosomes for degradation. Monogenic defects in processes regulating the protein composition of cilia are associated with syndromic disorders involving many organ systems, reflecting the pleotropic role of cilia during development and for tissue maintenance. Many of these ciliopathies have renal involvement, likely because of faulty polycystin signaling from cilia. Understanding the expression, maturation and trafficking of the polycystins helps understand PKD pathogenesis and suggests opportunities for therapeutic intervention.
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Affiliation(s)
- Jinghua Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA; Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
| | - Peter C Harris
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA; Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
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5
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Fisher S, Kuna D, Caspary T, Kahn RA, Sztul E. ARF family GTPases with links to cilia. Am J Physiol Cell Physiol 2020; 319:C404-C418. [PMID: 32520609 PMCID: PMC7500214 DOI: 10.1152/ajpcell.00188.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The ADP-ribosylation factor (ARF) superfamily of regulatory GTPases, including both the ARF and ARF-like (ARL) proteins, control a multitude of cellular functions, including aspects of vesicular traffic, lipid metabolism, mitochondrial architecture, the assembly and dynamics of the microtubule and actin cytoskeletons, and other pathways in cell biology. Considering their general utility, it is perhaps not surprising that increasingly ARF/ARLs have been found in connection to primary cilia. Here, we critically evaluate the current knowledge of the roles four ARF/ARLs (ARF4, ARL3, ARL6, ARL13B) play in cilia and highlight key missing information that would help move our understanding forward. Importantly, these GTPases are themselves regulated by guanine nucleotide exchange factors (GEFs) that activate them and by GTPase-activating proteins (GAPs) that act as both effectors and terminators of signaling. We believe that the identification of the GEFs and GAPs and better models of the actions of these GTPases and their regulators will provide a much deeper understanding and appreciation of the mechanisms that underly ciliary functions and the causes of a number of human ciliopathies.
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Affiliation(s)
- Skylar Fisher
- 1Department of Biochemistry, Emory University
School of Medicine, Atlanta,
Georgia
| | - Damian Kuna
- 2Department of Cell, Developmental and Integrative
Biology, University of Alabama at Birmingham,
Birmingham, Alabama
| | - Tamara Caspary
- 3Department of Human Genetics, Emory
University School of Medicine, Atlanta,
Georgia
| | - Richard A. Kahn
- 1Department of Biochemistry, Emory University
School of Medicine, Atlanta,
Georgia
| | - Elizabeth Sztul
- 2Department of Cell, Developmental and Integrative
Biology, University of Alabama at Birmingham,
Birmingham, Alabama
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6
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Yang H, Huang K. Dissecting the Vesicular Trafficking Function of IFT Subunits. Front Cell Dev Biol 2020; 7:352. [PMID: 32010685 PMCID: PMC6974671 DOI: 10.3389/fcell.2019.00352] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 12/05/2019] [Indexed: 12/22/2022] Open
Abstract
Intraflagellar transport (IFT) was initially identified as a transport machine with multiple protein subunits, and it is essential for the assembly, disassembly, and maintenance of cilium/flagellum, which serves as the nexus of extracellular-to-intracellular signal integration. To date, in addition to its well-established and indispensable roles in ciliated cells, most IFT subunits have presented more general functions of vesicular trafficking in the non-ciliated cells. Thus, this review aims to summarize the recent progress on the vesicular trafficking functions of the IFT subunits and to highlight the issues that may arise in future research.
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Affiliation(s)
- Huihui Yang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Institute of Hydrobiology, University of Chinese Academy of Sciences, Beijing, China
| | - Kaiyao Huang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
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7
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Ranjan P, Awasthi M, Snell WJ. Transient Internalization and Microtubule-Dependent Trafficking of a Ciliary Signaling Receptor from the Plasma Membrane to the Cilium. Curr Biol 2019; 29:2942-2947.e2. [PMID: 31422889 DOI: 10.1016/j.cub.2019.07.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/03/2019] [Accepted: 07/09/2019] [Indexed: 12/24/2022]
Abstract
Cilia are ancient organelles used by unicellular and multicellular organisms not only for motility but also to receive and respond to multiple environmental cues, including light, odorants, morphogens, growth factors, and contact with cilia of other cells. Much is known about the cellular mechanisms that deliver membrane proteins to cilia during ciliogenesis. Execution of a ciliary signaling pathway, however, can critically depend on rapid alterations in the receptor composition of the cilium itself, and our understanding of the mechanisms that underlie these rapid, regulated alterations remains limited [1-6]. In the bi-ciliated, unicellular alga Chlamydomonas reinhardtii, interactions between cilia of mating type plus and mating type minus gametes mediated by adhesion receptors SAG1 and SAD1 activate a ciliary signaling pathway [7]. In response, a large, inactive pool of SAG1 on the plasma membrane of plus gametes rapidly becomes enriched in the peri-ciliary membrane and enters the cilia to become active and maintain and enhance ciliary adhesion and signaling [8-14]. Ciliary entry per se of SAG1 is independent of anterograde intraflagellar transport (IFT) [13], but the rapid apical enrichment requires cytoplasmic microtubules and the retrograde IFT motor, dynein 1b [14]. Whether the receptors move laterally within the plasma membrane or transit internally during redistribution is unknown. Here, in coupled immunolocalization/biochemical studies on SAG1, we show that, within minutes after gamete activation is initiated, cell-surface SAG1 is internalized, associates with an apico-basally polarized array of cytoplasmic microtubules, and returns to the cell surface at a peri-ciliary staging area for entry into cilia.
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Affiliation(s)
- Peeyush Ranjan
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Mayanka Awasthi
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - William J Snell
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA.
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8
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Leigh MW, Horani A, Kinghorn B, O'Connor MG, Zariwala MA, Knowles MR. Primary Ciliary Dyskinesia (PCD): A genetic disorder of motile cilia. ACTA ACUST UNITED AC 2019; 4:51-75. [PMID: 31572664 DOI: 10.3233/trd-190036] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Margaret W Leigh
- Department of Pediatrics and Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Amjad Horani
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - BreAnna Kinghorn
- Seattle Children's Hospital, Department of Pediatrics, University of Washington School of Medicine; Seattle, Washington
| | - Michael G O'Connor
- Department of Pediatrics, Vanderbilt University Medical Center and Monroe Carell Jr Children's Hospital at Vanderbilt, Nashville, Tennessee
| | - Maimoona A Zariwala
- Department of Pathology/Lab Medicine and Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Michael R Knowles
- Department of Medicine and Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina
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9
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Finetti F, Cassioli C, Cianfanelli V, Onnis A, Paccagnini E, Kabanova A, Baldari CT. The intraflagellar transport protein IFT20 controls lysosome biogenesis by regulating the post-Golgi transport of acid hydrolases. Cell Death Differ 2019; 27:310-328. [PMID: 31142807 DOI: 10.1038/s41418-019-0357-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/16/2019] [Accepted: 05/14/2019] [Indexed: 01/08/2023] Open
Abstract
The assembly and function of the primary cilium depends on multimolecular intraflagellar transport (IFT) complexes that shuttle their cargo along the axonemal microtubules through their interaction with molecular motors. The IFT system has been moreover recently implicated in a reciprocal interplay between autophagy and ciliogenesis. We have previously reported that IFT20 and other components of the IFT complexes participate in the assembly of the immune synapse in the non-ciliated T cell, suggesting that other cellular processes regulated by the IFT system in ciliated cells, including autophagy, may be shared by cells lacking a cilium. Starting from the observation of a defect in autophagic clearance and an accumulation of lipid droplets in IFT20-deficient T cells, we show that IFT20 is required for lysosome biogenesis and function by controlling the lysosomal targeting of acid hydrolases. This function involves its ability to regulate the retrograde traffic of the cation-independent mannose-6-phosphate receptor (CI-MPR) to the trans-Golgi network, which is achieved by coupling recycling CI-MPRs to the microtubule motor dynein. Consistent with the lysosomal defect, an upregulation of the TFEB-dependent expression of the lysosomal gene network can be observed in IFT20-deficient cells, which is associated with defective tonic T-cell antigen receptor signaling and mTOR activity. We additionally show that the lysosome-related function of IFT20 extends to non-ciliated cells other than T cells, as well as to ciliated cells. Our findings provide the first evidence that a component of the IFT system that controls ciliogenesis is implicated in the biogenesis of lysosomes.
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Affiliation(s)
- Francesca Finetti
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy.
| | - Chiara Cassioli
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy
| | - Valentina Cianfanelli
- Cell Stress and Survival Unit, Danish Cancer Society Research Center, 2100, Copenhagen, Denmark
| | - Anna Onnis
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy
| | - Eugenio Paccagnini
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy
| | - Anna Kabanova
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy
| | - Cosima T Baldari
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy.
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10
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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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11
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Roman AC, Garrido-Jimenez S, Diaz-Chamorro S, Centeno F, Carvajal-Gonzalez JM. Centriole Positioning: Not Just a Little Dot in the Cell. Results Probl Cell Differ 2019; 67:201-221. [PMID: 31435796 DOI: 10.1007/978-3-030-23173-6_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Organelle positioning as many other morphological parameters in a cell is not random. Centriole positioning as centrosomes or ciliary basal bodies is not an exception to this rule in cell biology. Indeed, centriole positioning is a tightly regulated process that occurs during development, and it is critical for many organs to function properly, not just during development but also in the adulthood. In this book chapter, we overview our knowledge on centriole positioning in different and highly specialized animal cells like photoreceptor or ependymal cells. We will also discuss recent advances in the discovery of molecular pathways involved in this process, mostly related to the cytoskeleton and the cell polarity pathways. And finally, we present quantitative methods that have been used to assess centriole positioning in different cell types although mostly in epithelial cells.
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Affiliation(s)
- Angel-Carlos Roman
- Facultad de Ciencias, Departamento de Bioquímica, Biología Molecular y Genética, Universidad de Extremadura, Badajoz, Spain
| | - Sergio Garrido-Jimenez
- Facultad de Ciencias, Departamento de Bioquímica, Biología Molecular y Genética, Universidad de Extremadura, Badajoz, Spain
| | - Selene Diaz-Chamorro
- Facultad de Ciencias, Departamento de Bioquímica, Biología Molecular y Genética, Universidad de Extremadura, Badajoz, Spain
| | - Francisco Centeno
- Facultad de Ciencias, Departamento de Bioquímica, Biología Molecular y Genética, Universidad de Extremadura, Badajoz, Spain
| | - Jose Maria Carvajal-Gonzalez
- Facultad de Ciencias, Departamento de Bioquímica, Biología Molecular y Genética, Universidad de Extremadura, Badajoz, Spain.
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12
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Morthorst SK, Christensen ST, Pedersen LB. Regulation of ciliary membrane protein trafficking and signalling by kinesin motor proteins. FEBS J 2018; 285:4535-4564. [PMID: 29894023 DOI: 10.1111/febs.14583] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/09/2018] [Accepted: 06/11/2018] [Indexed: 12/14/2022]
Abstract
Primary cilia are antenna-like sensory organelles that regulate a substantial number of cellular signalling pathways in vertebrates, both during embryonic development as well as in adulthood, and mutations in genes coding for ciliary proteins are causative of an expanding group of pleiotropic diseases known as ciliopathies. Cilia consist of a microtubule-based axoneme core, which is subtended by a basal body and covered by a bilayer lipid membrane of unique protein and lipid composition. Cilia are dynamic organelles, and the ability of cells to regulate ciliary protein and lipid content in response to specific cellular and environmental cues is crucial for balancing ciliary signalling output. Here we discuss mechanisms involved in regulation of ciliary membrane protein trafficking and signalling, with main focus on kinesin-2 and kinesin-3 family members.
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13
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Horani A, Ferkol TW. Advances in the Genetics of Primary Ciliary Dyskinesia: Clinical Implications. Chest 2018; 154:645-652. [PMID: 29800551 DOI: 10.1016/j.chest.2018.05.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/11/2018] [Accepted: 05/06/2018] [Indexed: 11/15/2022] Open
Abstract
Primary ciliary dyskinesia is a rare genetic disease of the motile cilia and is one of a rapidly expanding collection of disorders known as ciliopathies. Patients with primary ciliary dyskinesia have diverse clinical manifestations, including chronic upper and lower respiratory tract disease, left-right laterality defects, and infertility. In recent years, our understanding of the genetics of primary ciliary dyskinesia has rapidly advanced. A growing number of disease-associated genes and pathogenic mutations have been identified, which encode axonemal, cytoplasmic, and regulatory proteins involved in the assembly, structure, and function of motile cilia. Our knowledge of cilia genetics and the function of the proteins encoded has led to a greater understanding of the clinical manifestations of motile ciliopathies. These advances have changed our approach toward diagnostic testing for primary ciliary dyskinesia. In this review, we will describe how new insights into genetics have allowed us to define the clinical features of primary ciliary dyskinesia, revolutionize diagnostics, and reveal previously unrecognized genotype-phenotype relationships in primary ciliary dyskinesia.
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Affiliation(s)
- Amjad Horani
- Department of Pediatrics, Washington University School of Medicine, St Louis, MO
| | - Thomas W Ferkol
- Department of Pediatrics, Washington University School of Medicine, St Louis, MO; Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO.
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14
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Lesiak AJ, Brodsky M, Cohenca N, Croicu AG, Neumaier JF. Restoration of Physiological Expression of 5-HT 6 Receptor into the Primary Cilia of Null Mutant Neurons Lengthens Both Primary Cilia and Dendrites. Mol Pharmacol 2018; 94:731-742. [PMID: 29678909 DOI: 10.1124/mol.117.111583] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/13/2018] [Indexed: 12/14/2022] Open
Abstract
5-HT6 (serotonin) receptors are promising targets for a variety of neuropsychiatric disorders and have been linked to several cellular signaling cascades. Endogenous 5-HT6 receptors are restricted to the primary neuronal cilium, a small sensory organelle stemming from the cell body that receives numerous extrasynaptic signals. Inhibition of 5-HT6 receptors decreases cilia length in primary neuronal cultures, but the signaling mechanisms involved are still unclear. Intense overexpression of exogenous 5-HT6 receptors increases the probability for receptors to localize outside the primary cilium and have been associated with changes in cilia morphology and dendritic outgrowth. In the present study, we explore the role of 5-HT6R rescue on neuronal morphology in primary neuronal cultures from 5-HT6R-KO mice, at the same time maintaining a more physiologic level of expression, wherein the receptor localizes to cilia in 80%-90% of neurons (similar to endogenous 5-HT6R localization). We found that rescue of 5-HT6R expression is sufficient to increase cilia length and dendritic outgrowth, but primarily in neurons in which the receptor is located exclusively in the primary cilia. Additionally, we found that expression of 5-HT6R mutants deficient in agonist-stimulated cAMP or without the predicted Fyn kinase binding domain maintained constitutive activity for stimulating cAMP and still increased the length of cilia, and that the proposed Fyn kinase domain was required for stimulating dendritic outgrowth. These findings highlight the complexity of 5-HT6R function and localization, particularly with the use of exogenous overexpression, and provide greater understanding and potential mechanisms for 5-HT6R drug therapies.
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Affiliation(s)
- Atom J Lesiak
- Department of Psychiatry and Behavioral Science, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Matthew Brodsky
- Department of Psychiatry and Behavioral Science, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Nathalie Cohenca
- Department of Psychiatry and Behavioral Science, Department of Pharmacology, University of Washington, Seattle, Washington
| | - Alexandra G Croicu
- Department of Psychiatry and Behavioral Science, Department of Pharmacology, University of Washington, Seattle, Washington
| | - John F Neumaier
- Department of Psychiatry and Behavioral Science, Department of Pharmacology, University of Washington, Seattle, Washington
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15
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Shimada H, Lu Q, Insinna-Kettenhofen C, Nagashima K, English MA, Semler EM, Mahgerefteh J, Cideciyan AV, Li T, Brooks BP, Gunay-Aygun M, Jacobson SG, Cogliati T, Westlake CJ, Swaroop A. In Vitro Modeling Using Ciliopathy-Patient-Derived Cells Reveals Distinct Cilia Dysfunctions Caused by CEP290 Mutations. Cell Rep 2018; 20:384-396. [PMID: 28700940 DOI: 10.1016/j.celrep.2017.06.045] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 05/03/2017] [Accepted: 06/19/2017] [Indexed: 02/06/2023] Open
Abstract
Mutations in CEP290, a transition zone protein in primary cilia, cause diverse ciliopathies, including Leber congenital amaurosis (LCA) and Joubert-syndrome and related disorders (JSRD). We examined cilia biogenesis and function in cells derived from CEP290-LCA and CEP290-JSRD patients. CEP290 protein was reduced in LCA fibroblasts with no detectable impact on cilia; however, optic cups derived from induced pluripotent stem cells (iPSCs) of CEP290-LCA patients displayed less developed photoreceptor cilia. Lack of CEP290 in JSRD fibroblasts resulted in abnormal cilia and decreased ciliogenesis. We observed selectively reduced localization of ADCY3 and ARL13B. Notably, Hedgehog signaling was augmented in CEP290-JSRD because of enhanced ciliary transport of Smoothened and GPR161. These results demonstrate a direct correlation between the extent of ciliogenesis defects in fibroblasts and photoreceptors with phenotypic severity in JSRD and LCA, respectively, and strengthen the role of CEP290 as a selective ciliary gatekeeper for transport of signaling molecules in and out of the cilium.
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Affiliation(s)
- Hiroko Shimada
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Quanlong Lu
- Laboratory of Cell and Developmental Signaling, National Cancer Institute - Frederick, Frederick, MD 21702, USA
| | | | - Kunio Nagashima
- Electron Microscope Laboratory, Leidos Biomedical Research, Inc., National Cancer Institute - Frederick, Frederick, MD 21702, USA
| | - Milton A English
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Elizabeth M Semler
- Laboratory of Cell and Developmental Signaling, National Cancer Institute - Frederick, Frederick, MD 21702, USA
| | - Jacklyn Mahgerefteh
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Artur V Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tiansen Li
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Brian P Brooks
- Pediatric, Developmental, and Genetic Eye Disease Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Meral Gunay-Aygun
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA; Department of Pediatrics, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Samuel G Jacobson
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tiziana Cogliati
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Christopher J Westlake
- Laboratory of Cell and Developmental Signaling, National Cancer Institute - Frederick, Frederick, MD 21702, USA.
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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16
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Antagonistic regulation of trafficking to Caenorhabditis elegans sensory cilia by a Retinal Degeneration 3 homolog and retromer. Proc Natl Acad Sci U S A 2017; 115:E438-E447. [PMID: 29282322 DOI: 10.1073/pnas.1712302115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Sensory neurons often possess cilia with elaborate membrane structures that are adapted to the sensory modality of the host cell. Mechanisms that target sensory transduction proteins to these specialized membrane domains remain poorly understood. Here, we show that a homolog of the human retinal dystrophy gene Retinal Degeneration 3 (RD3) is a Golgi-associated protein required for efficient trafficking of a sensory receptor, the receptor-type guanylate cyclase GCY-9, to cilia in chemosensory neurons of the nematode Caenorhabditis elegans The trafficking defect caused by mutation of the nematode RD3 homolog is suppressed in vivo by mutation of key components of the retromer complex, which mediates recycling of cargo from endosomes to the Golgi. Our data show that there exists a critical balance in sensory neurons between the rates of anterograde and retrograde trafficking of cargo destined for the sensory cilium and this balance requires molecular specialization at an early stage of the secretory pathway.
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17
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Seo S, Datta P. Photoreceptor outer segment as a sink for membrane proteins: hypothesis and implications in retinal ciliopathies. Hum Mol Genet 2017; 26:R75-R82. [PMID: 28453661 DOI: 10.1093/hmg/ddx163] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 04/24/2017] [Indexed: 12/28/2022] Open
Abstract
The photoreceptor outer segment (OS) is a unique modification of the primary cilium, specialized for light perception. Being homologous organelles, the primary cilium and the OS share common building blocks and molecular machinery to construct and maintain them. The OS, however, has several unique structural features that are not seen in primary cilia. Although these unique features of the OS have been well documented, their implications in protein localization have been under-appreciated. In this review, we compare the structural properties of the primary cilium and the OS, and propose a hypothesis that the OS can act as a sink for membrane proteins. We further discuss the implications of this hypothesis in polarized protein localization in photoreceptors and mechanisms of photoreceptor degeneration in retinal ciliopathies.
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Affiliation(s)
- Seongjin Seo
- Department of Ophthalmology and Visual Sciences, Wynn Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Poppy Datta
- Department of Ophthalmology and Visual Sciences, Wynn Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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18
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Primary Cilium-Dependent Signaling Mechanisms. Int J Mol Sci 2017; 18:ijms18112272. [PMID: 29143784 PMCID: PMC5713242 DOI: 10.3390/ijms18112272] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/13/2017] [Accepted: 10/25/2017] [Indexed: 01/02/2023] Open
Abstract
Primary cilia are hair-like organelles and play crucial roles in vertebrate development, organogenesis, health, and many genetic disorders. A primary cilium is a mechano-sensory organelle that responds to mechanical stimuli in the micro-environment. A cilium is also a chemosensor that senses chemical signals surrounding a cell. The overall function of a cilium is therefore to act as a communication hub to transfer extracellular signals into intracellular responses. Although intracellular calcium has been one of the most studied signaling messengers that transmit extracellular signals into the cells, calcium signaling by various ion channels remains a topic of interest in the field. This may be due to a broad spectrum of cilia functions that are dependent on or independent of utilizing calcium as a second messenger. We therefore revisit and discuss the calcium-dependent and calcium-independent ciliary signaling pathways of Hedgehog, Wnt, PDGFR, Notch, TGF-β, mTOR, OFD1 autophagy, and other GPCR-associated signaling. All of these signaling pathways play crucial roles in various cellular processes, such as in organ and embryonic development, cardiac functioning, planar cell polarity, transactivation, differentiation, the cell cycle, apoptosis, tissue homeostasis, and the immune response.
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19
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Veleri S, Nellissery J, Mishra B, Manjunath SH, Brooks MJ, Dong L, Nagashima K, Qian H, Gao C, Sergeev YV, Huang XF, Qu J, Lu F, Cideciyan AV, Li T, Jin ZB, Fariss RN, Ratnapriya R, Jacobson SG, Swaroop A. REEP6 mediates trafficking of a subset of Clathrin-coated vesicles and is critical for rod photoreceptor function and survival. Hum Mol Genet 2017; 26:2218-2230. [PMID: 28369466 PMCID: PMC5458339 DOI: 10.1093/hmg/ddx111] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/16/2017] [Indexed: 01/20/2023] Open
Abstract
In retinal photoreceptors, vectorial transport of cargo is critical for transduction of visual signals, and defects in intracellular trafficking can lead to photoreceptor degeneration and vision impairment. Molecular signatures associated with routing of transport vesicles in photoreceptors are poorly understood. We previously reported the identification of a novel rod photoreceptor specific isoform of Receptor Expression Enhancing Protein (REEP) 6, which belongs to a family of proteins involved in intracellular transport of receptors to the plasma membrane. Here we show that loss of REEP6 in mice (Reep6−/−) results in progressive retinal degeneration. Rod photoreceptor dysfunction is observed in Reep6−/− mice as early as one month of age and associated with aberrant accumulation of vacuole-like structures at the apical inner segment and reduction in selected rod phototransduction proteins. We demonstrate that REEP6 is detected in a subset of Clathrin-coated vesicles and interacts with the t-SNARE, Syntaxin3. In concordance with the rod degeneration phenotype in Reep6−/− mice, whole exome sequencing identified homozygous REEP6-E75K mutation in two retinitis pigmentosa families of different ethnicities. Our studies suggest a critical function of REEP6 in trafficking of cargo via a subset of Clathrin-coated vesicles to selected membrane sites in retinal rod photoreceptors.
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Affiliation(s)
- Shobi Veleri
- Neurobiology Neurodegeneration and Repair Laboratory
| | | | | | | | | | - Lijin Dong
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kunio Nagashima
- Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Haohua Qian
- Visual Function Core, 5Biological Imaging Core
| | - Chun Gao
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yuri V Sergeev
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiu-Feng Huang
- The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China and
| | - Jia Qu
- The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China and
| | - Fan Lu
- The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China and
| | - Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tiansen Li
- Neurobiology Neurodegeneration and Repair Laboratory
| | - Zi-Bing Jin
- The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China and
| | - Robert N Fariss
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anand Swaroop
- Neurobiology Neurodegeneration and Repair Laboratory
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20
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Mukhopadhyay S, Badgandi HB, Hwang SH, Somatilaka B, Shimada IS, Pal K. Trafficking to the primary cilium membrane. Mol Biol Cell 2017; 28:233-239. [PMID: 28082521 PMCID: PMC5231892 DOI: 10.1091/mbc.e16-07-0505] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 11/14/2016] [Accepted: 11/15/2016] [Indexed: 12/13/2022] Open
Abstract
The primary cilium has been found to be associated with a number of cellular signaling pathways, such as vertebrate hedgehog signaling, and implicated in the pathogenesis of diseases affecting multiple organs, including the neural tube, kidney, and brain. The primary cilium is the site where a subset of the cell's membrane proteins is enriched. However, pathways that target and concentrate membrane proteins in cilia are not well understood. Processes determining the level of proteins in the ciliary membrane include entry into the compartment, removal, and retention by diffusion barriers such as the transition zone. Proteins that are concentrated in the ciliary membrane are also localized to other cellular sites. Thus it is critical to determine the particular role for ciliary compartmentalization in sensory reception and signaling pathways. Here we provide a brief overview of our current understanding of compartmentalization of proteins in the ciliary membrane and the dynamics of trafficking into and out of the cilium. We also discuss major unanswered questions regarding the role that defects in ciliary compartmentalization might play in disease pathogenesis. Understanding the trafficking mechanisms that underlie the role of ciliary compartmentalization in signaling might provide unique approaches for intervention in progressive ciliopathies.
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Affiliation(s)
- Saikat Mukhopadhyay
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Hemant B Badgandi
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Sun-Hee Hwang
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | | | - Issei S Shimada
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Kasturi Pal
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390
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21
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Goodman L, Zallocchi M. Integrin α8 and Pcdh15 act as a complex to regulate cilia biogenesis in sensory cells. J Cell Sci 2017; 130:3698-3712. [PMID: 28883094 DOI: 10.1242/jcs.206201] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 09/01/2017] [Indexed: 01/21/2023] Open
Abstract
The way an organism perceives its surroundings depends on sensory systems and the highly specialized cilia present in the neurosensory cells. Here, we describe the existence of an integrin α8 (Itga8) and protocadherin-15a (Pcdh15a) ciliary complex in neuromast hair cells in a zebrafish model. Depletion of the complex via downregulation or loss-of-function mutation leads to a dysregulation of cilia biogenesis and endocytosis. At the molecular level, removal of the complex blocks the access of Rab8a into the cilia as well as normal recruitment of ciliary cargo by centriolar satellites. These defects can be reversed by the introduction of a constitutively active form of Rhoa, suggesting that Itga8-Pcdh15a complex mediates its effect through the activation of this small GTPase and probably by the regulation of actin cytoskeleton dynamics. Our data points to a novel mechanism involved in the regulation of sensory cilia development, with the corresponding implications for normal sensory function.
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Affiliation(s)
- Linda Goodman
- Center for Sensory Neuroscience, Boys Town National Research Hospital, Omaha, NE 68131, USA
| | - Marisa Zallocchi
- Center for Sensory Neuroscience, Boys Town National Research Hospital, Omaha, NE 68131, USA
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22
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Prevo B, Scholey JM, Peterman EJG. Intraflagellar transport: mechanisms of motor action, cooperation, and cargo delivery. FEBS J 2017; 284:2905-2931. [PMID: 28342295 PMCID: PMC5603355 DOI: 10.1111/febs.14068] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/20/2017] [Accepted: 03/23/2017] [Indexed: 02/06/2023]
Abstract
Intraflagellar transport (IFT) is a form of motor-dependent cargo transport that is essential for the assembly, maintenance, and length control of cilia, which play critical roles in motility, sensory reception, and signal transduction in virtually all eukaryotic cells. During IFT, anterograde kinesin-2 and retrograde IFT dynein motors drive the bidirectional transport of IFT trains that deliver cargo, for example, axoneme precursors such as tubulins as well as molecules of the signal transduction machinery, to their site of assembly within the cilium. Following its discovery in Chlamydomonas, IFT has emerged as a powerful model system for studying general principles of motor-dependent cargo transport and we now appreciate the diversity that exists in the mechanism of IFT within cilia of different cell types. The absence of heterotrimeric kinesin-2 function, for example, causes a complete loss of both IFT and cilia in Chlamydomonas, but following its loss in Caenorhabditis elegans, where its primary function is loading the IFT machinery into cilia, homodimeric kinesin-2-driven IFT persists and assembles a full-length cilium. Generally, heterotrimeric kinesin-2 and IFT dynein motors are thought to play widespread roles as core IFT motors, whereas homodimeric kinesin-2 motors are accessory motors that mediate different functions in a broad range of cilia, in some cases contributing to axoneme assembly or the delivery of signaling molecules but in many other cases their ciliary functions, if any, remain unknown. In this review, we focus on mechanisms of motor action, motor cooperation, and motor-dependent cargo delivery during IFT.
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Affiliation(s)
- Bram Prevo
- Department of Cellular & Molecular Medicine, University of California San Diego, CA, USA
- Ludwig Institute for Cancer Research, San Diego, CA, USA
| | - Jonathan M Scholey
- Department of Molecular & Cell Biology, University of California Davis, CA, USA
| | - Erwin J G Peterman
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit, Amsterdam, The Netherlands
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23
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Piasecki BP, Sasani TA, Lessenger AT, Huth N, Farrell S. MAPK-15 is a ciliary protein required for PKD-2 localization and male mating behavior in Caenorhabditis elegans. Cytoskeleton (Hoboken) 2017; 74:390-402. [PMID: 28745435 DOI: 10.1002/cm.21387] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 06/14/2017] [Accepted: 07/05/2017] [Indexed: 12/16/2022]
Abstract
Cilia are conserved cellular structures that facilitate sensory-based processes, including those required for neuronal and kidney functions. Here, we show that the human mitogen activated kinase-15 (MAPK-15) ortholog in Caenorhabditis elegans encodes a ciliary protein. A strain harboring a mutation in the catalytic site of the kinase domain results in ciliary-specific defects in tail neurons of both hermaphrodite and male worms, manifesting in dye uptake, dendrite extension, and male mating behavior defects. Transgenic-fusion constructs for two mapk-15 isoforms (A and C) with full-length kinase domains were generated. Expression of either the A- or C-specific isoform rescues the dye-filling and male-mating defective phenotypes, confirming the ciliary function of mapk-15. Expression of mapk-15 occurs in many ciliated-sensory neurons of the head and tail in hermaphrodite and male worms. Localization of MAPK-15 isoforms A and C occurs in the cell body, dendritic processes, and cilia. A C. elegans ortholog of polycystin-2, a protein that when defective in mammals results in autosomal dominant polycystic kidney disease, is mislocalized in the male ray neurons of mapk-15 mutant worms. Expression of the mapk-15 gene by the pkd-2 promoter partially rescues the male-mating defects observed in mapk-15 mutant animals. Expression of mapk-15 is DAF-19/RFX dependent in some CSNs and DAF-19/RFX independent in others. Collectively, these data suggest that MAPK-15 functions upstream of PKD-2 localization to modulate ciliary sensory functions.
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Affiliation(s)
| | - Thomas A Sasani
- Department of Biology, Lawrence University, Appleton, Wisconsin.,Department of Human Genetics, University of Utah, Salt Lake City, Utah
| | | | - Nicholas Huth
- Department of Biology, Lawrence University, Appleton, Wisconsin
| | - Shane Farrell
- Department of Biology, Lawrence University, Appleton, Wisconsin
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24
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Ding J, Shao L, Yao Y, Tong X, Liu H, Yue S, Xie L, Cheng SY. DGKδ triggers endoplasmic reticulum release of IFT88-containing vesicles destined for the assembly of primary cilia. Sci Rep 2017; 7:5296. [PMID: 28706295 PMCID: PMC5509727 DOI: 10.1038/s41598-017-05680-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 06/01/2017] [Indexed: 11/16/2022] Open
Abstract
The morphogenic factor Sonic hedgehog (Shh) signals through the primary cilium, which relies on intraflagellar transport to maintain its structural integrity and function. However, the process by which protein and lipid cargos are delivered to the primary cilium from their sites of synthesis still remains poorly characterized. Here, we report that diacylglycerol kinase δ (DGKδ), a residential lipid kinase in the endoplasmic reticulum, triggers the release of IFT88-containing vesicles from the ER exit sites (ERES), thereby setting forth their movement to the primary cilium. Encoded by the gene whose mutations originally implicated the primary cilium as the venue of Shh signaling, IFT88 is known to be part of the complex B that drives the anterograde transport within cilia. We show that IFT88 interacts with DGKδ, and is associated with COPII-coated vesicles at the ERES. Using a combination of RNAi silencing and gene knockout strategies, we further show that DGKδ is required for supporting Shh signaling both in vitro and in vivo, demonstrating the physiological significance of this regulation.
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Affiliation(s)
- Jie Ding
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China
| | - Lei Shao
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China
| | - Yixing Yao
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China
| | - Xin Tong
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China
| | - Huaize Liu
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China
| | - Shen Yue
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China
| | - Lu Xie
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China
| | - Steven Y Cheng
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing, Jiangsu, 211166, China.
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25
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Takao D, Kamimura S. Simulation of intra-ciliary diffusion suggests a novel role of primary cilia as a cell-signaling enhancer. Dev Growth Differ 2017; 59:415-422. [PMID: 28573753 DOI: 10.1111/dgd.12360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 12/16/2022]
Abstract
Besides the role to generate a fluid flow in the surrounding medium, eukaryotic cilia have a crucial function in sensing external signals such as chemical or mechanical stimuli. A large body of work has shown that cilia are frequently found in various types of sensory cells and are closely related to many regulatory mechanisms in differentiation and development. However, we do not yet have a definitive answer to the fundamental question, "why cilia?" It has been a long-standing mystery why cells use cilia for sensing external signals. To shed light on this, we sought to describe the kinetics of signaling with theoretical approaches. Based on the results, here we propose a new role of cilia as a cell-signaling enhancer. The enhancing effect comes from restricted volume for the free intra-ciliary diffusion of molecules due to the cylindrical shape of cilia, which can facilitate quick accumulation of intracellular signaling molecules. Our simulations demonstrate that both the rate and amplitude of response in signal transduction depend on where the membrane receptors or channels are located along the ciliary shaft. In addition, the calculated transfer function of cilia regarded as a transmitter of external signals also suggests the properties of cilia as a signal enhancer. Since such unique composition of receptors and channels in cilia is found in various types of eukaryotic cells, signal enhancing is presumably one of the most essential and conserved roles of cilia.
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Affiliation(s)
- Daisuke Takao
- Department of Molecular Genetics, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan
| | - Shinji Kamimura
- Department of Biological Sciences, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112-8551, Japan
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26
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Pearring JN, San Agustin JT, Lobanova ES, Gabriel CJ, Lieu EC, Monis WJ, Stuck MW, Strittmatter L, Jaber SM, Arshavsky VY, Pazour GJ. Loss of Arf4 causes severe degeneration of the exocrine pancreas but not cystic kidney disease or retinal degeneration. PLoS Genet 2017; 13:e1006740. [PMID: 28410364 PMCID: PMC5409180 DOI: 10.1371/journal.pgen.1006740] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/28/2017] [Accepted: 04/05/2017] [Indexed: 12/16/2022] Open
Abstract
Arf4 is proposed to be a critical regulator of membrane protein trafficking in early secretory pathway. More recently, Arf4 was also implicated in regulating ciliary trafficking, however, this has not been comprehensively tested in vivo. To directly address Arf4’s role in ciliary transport, we deleted Arf4 specifically in either rod photoreceptor cells, kidney, or globally during the early postnatal period. Arf4 deletion in photoreceptors did not cause protein mislocalization or retinal degeneration, as expected if Arf4 played a role in protein transport to the ciliary outer segment. Likewise, Arf4 deletion in kidney did not cause cystic disease, as expected if Arf4 were involved in general ciliary trafficking. In contrast, global Arf4 deletion in the early postnatal period resulted in growth restriction, severe pancreatic degeneration and early death. These findings are consistent with Arf4 playing a critical role in endomembrane trafficking, particularly in the pancreas, but not in ciliary function. Primary cilia are sensory organelles found on most cells and contain specific receptors that detect extracellular stimuli. Defects in trafficking receptors to cilia cause a diverse set of diseases called ciliopathies, which include polycystic kidney disease, obesity, cerebral anomalies and retinal degeneration. Based mostly on in vitro studies, the small GTPase Arf4 was thought to be critically important for localizing rhodopsin to the outer segment of photoreceptor cells and cystoproteins to kidney cilia. Here we genetically remove Arf4 from mice in either a tissue specific or time dependent manner. To our surprise, the loss of Arf4 does not cause retinal degeneration or cystic kidney disease. Since ciliary dysfunction causes retinal degeneration and cystic disease, our findings indicate that Arf4 does not play a role in ciliary function. Instead, mice have zymogen granule defects and degeneration of the exocrine pancreas supporting roles for Arf4 in regulating endomembrane trafficking in specific cells.
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Affiliation(s)
- Jillian N. Pearring
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Jovenal T. San Agustin
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Ekaterina S. Lobanova
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Christopher J. Gabriel
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Eric C. Lieu
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - William J. Monis
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Michael W. Stuck
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Lara Strittmatter
- Electron Microscopy Core, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Samer M. Jaber
- Department of Animal Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Vadim Y. Arshavsky
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Gregory J. Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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27
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Lechtreck KF, Van De Weghe JC, Harris JA, Liu P. Protein transport in growing and steady-state cilia. Traffic 2017; 18:277-286. [PMID: 28248449 DOI: 10.1111/tra.12474] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 02/22/2017] [Accepted: 02/22/2017] [Indexed: 12/18/2022]
Abstract
Cilia and eukaryotic flagella are threadlike cell extensions with motile and sensory functions. Their assembly requires intraflagellar transport (IFT), a bidirectional motor-driven transport of protein carriers along the axonemal microtubules. IFT moves ample amounts of structural proteins including tubulin into growing cilia likely explaining its critical role for assembly. IFT continues in non-growing cilia contributing to a variety of processes ranging from axonemal maintenance and the export of non-ciliary proteins to cell locomotion and ciliary signaling. Here, we discuss recent data on cues regulating the type, amount and timing of cargo transported by IFT. A regulation of IFT-cargo interactions is critical to establish, maintain and adjust ciliary length, protein composition and function.
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Affiliation(s)
- Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia
| | | | | | - Peiwei Liu
- Department of Cellular Biology, University of Georgia, Athens, Georgia
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28
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Badgandi HB, Hwang SH, Shimada IS, Loriot E, Mukhopadhyay S. Tubby family proteins are adapters for ciliary trafficking of integral membrane proteins. J Cell Biol 2017; 216:743-760. [PMID: 28154160 PMCID: PMC5350516 DOI: 10.1083/jcb.201607095] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/25/2016] [Accepted: 01/09/2017] [Indexed: 01/19/2023] Open
Abstract
Trafficking of integral membrane proteins to cilia is poorly understood. Badgandi et al. show that tubby family proteins TULP3 and TUB act as general adapters for ciliary trafficking of structurally diverse integral membrane cargo like GCPRs and the polycystin 1/2 complex. The primary cilium is a paradigmatic organelle for studying compartmentalized signaling; however, unlike soluble protein trafficking, processes targeting integral membrane proteins to cilia are poorly understood. In this study, we determine that the tubby family protein TULP3 functions as a general adapter for ciliary trafficking of structurally diverse integral membrane cargo, including multiple reported and novel rhodopsin family G protein–coupled receptors (GPCRs) and the polycystic kidney disease–causing polycystin 1/2 complex. The founding tubby family member TUB also localizes to cilia similar to TULP3 and determines trafficking of a subset of these GPCRs to neuronal cilia. Using minimal ciliary localization sequences from GPCRs and fibrocystin (also implicated in polycystic kidney disease), we demonstrate these motifs to be sufficient and TULP3 dependent for ciliary trafficking. We propose a three-step model for TULP3/TUB-mediated ciliary trafficking, including the capture of diverse membrane cargo by the tubby domain in a phosphoinositide 4,5-bisphosphate (PI(4,5)P2)-dependent manner, ciliary delivery by intraflagellar transport complex A binding to the TULP3/TUB N terminus, and subsequent release into PI(4,5)P2-deficient ciliary membrane.
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Affiliation(s)
- Hemant B Badgandi
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Sun-Hee Hwang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Issei S Shimada
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Evan Loriot
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390.,STARS Program, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Jesuit College Preparatory School of Dallas, Dallas, TX 75244
| | - Saikat Mukhopadhyay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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29
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Wensel TG, Zhang Z, Anastassov IA, Gilliam JC, He F, Schmid MF, Robichaux MA. Structural and molecular bases of rod photoreceptor morphogenesis and disease. Prog Retin Eye Res 2016; 55:32-51. [PMID: 27352937 PMCID: PMC5112133 DOI: 10.1016/j.preteyeres.2016.06.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/15/2022]
Abstract
The rod cell has an extraordinarily specialized structure that allows it to carry out its unique function of detecting individual photons of light. Both the structural features of the rod and the metabolic processes required for highly amplified light detection seem to have rendered the rod especially sensitive to structural and metabolic defects, so that a large number of gene defects are primarily associated with rod cell death and give rise to blinding retinal dystrophies. The structures of the rod, especially those of the sensory cilium known as the outer segment, have been the subject of structural, biochemical, and genetic analysis for many years, but the molecular bases for rod morphogenesis and for cell death in rod dystrophies are still poorly understood. Recent developments in imaging technology, such as cryo-electron tomography and super-resolution fluorescence microscopy, in gene sequencing technology, and in gene editing technology are rapidly leading to new breakthroughs in our understanding of these questions. A summary is presented of our current understanding of selected aspects of these questions, highlighting areas of uncertainty and contention as well as recent discoveries that provide new insights. Examples of structural data from emerging imaging technologies are presented.
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Affiliation(s)
- Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Zhixian Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ivan A Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jared C Gilliam
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Feng He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Schmid
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael A Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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30
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Bragina EE, Arifulin EA, Senchenkov EP. Genetically determined and functional human sperm motility decrease. Russ J Dev Biol 2016. [DOI: 10.1134/s1062360416050027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Paige Taylor S, Kunova Bosakova M, Varecha M, Balek L, Barta T, Trantirek L, Jelinkova I, Duran I, Vesela I, Forlenza KN, Martin JH, Hampl A, Bamshad M, Nickerson D, Jaworski ML, Song J, Ko HW, Cohn DH, Krakow D, Krejci P. An inactivating mutation in intestinal cell kinase, ICK, impairs hedgehog signalling and causes short rib-polydactyly syndrome. Hum Mol Genet 2016; 25:3998-4011. [PMID: 27466187 DOI: 10.1093/hmg/ddw240] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 06/27/2016] [Accepted: 06/29/2016] [Indexed: 12/30/2022] Open
Abstract
The short rib polydactyly syndromes (SRPS) are a group of recessively inherited, perinatal-lethal skeletal disorders primarily characterized by short ribs, shortened long bones, varying types of polydactyly and concomitant visceral abnormalities. Mutations in several genes affecting cilia function cause SRPS, revealing a role for cilia function in skeletal development. To identify additional SRPS genes and discover novel ciliary molecules required for normal skeletogenesis, we performed exome sequencing in a cohort of patients and identified homozygosity for a missense mutation, p.E80K, in Intestinal Cell Kinase, ICK, in one SRPS family. The p.E80K mutation abolished serine/threonine kinase activity, resulting in altered ICK subcellular and ciliary localization, increased cilia length, aberrant cartilage growth plate structure, defective Hedgehog and altered ERK signalling. These data identify ICK as an SRPS-associated gene and reveal that abnormalities in signalling pathways contribute to defective skeletogenesis.
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Affiliation(s)
- S Paige Taylor
- Department of Human Genetics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | | | - Miroslav Varecha
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic
| | - Lukas Balek
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic
| | - Tomas Barta
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic
| | - Lukas Trantirek
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500 Brno, Czech Republic
| | - Iva Jelinkova
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic
| | - Ivan Duran
- Department of Orthopaedic Surgery.,Department of Human Genetics.,Department of Obstetrics and Gynecology, Orthopaedic Institute for Children, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Iva Vesela
- Institute of Experimental Biology, Masaryk University, 62500 Brno, Czech Republic
| | - Kimberly N Forlenza
- Department of Orthopaedic Surgery.,Department of Human Genetics.,Department of Obstetrics and Gynecology, Orthopaedic Institute for Children, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Jorge H Martin
- Department of Orthopaedic Surgery.,Department of Human Genetics.,Department of Obstetrics and Gynecology, Orthopaedic Institute for Children, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ales Hampl
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic
| | | | - Michael Bamshad
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA.,Division of Genetic Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA.,Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Deborah Nickerson
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | | | - Jieun Song
- College of Pharmacy, Dongguk University-Seoul, Goyang 410-820, Korea
| | - Hyuk Wan Ko
- College of Pharmacy, Dongguk University-Seoul, Goyang 410-820, Korea
| | - Daniel H Cohn
- Department of Orthopaedic Surgery.,International Skeletal Dysplasia Registry, University of California Los Angeles, Los Angeles, CA 90095, USA.,Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Deborah Krakow
- Department of Human Genetics, University of California Los Angeles, Los Angeles, CA 90095, USA .,Department of Orthopaedic Surgery.,International Skeletal Dysplasia Registry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic.,Department of Orthopaedic Surgery.,International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic
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32
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Abstract
Primary ciliary dyskinesia (PCD) is a genetic disease of motile cilia, which belongs to a group of disorders resulting from dysfunction of cilia, collectively known as ciliopathies. Insights into the genetics and phenotypes of PCD have grown over the last decade, in part propagated by the discovery of a number of novel cilia-related genes. These genes encode proteins that segregate into structural axonemal, regulatory, as well as cytoplasmic assembly proteins. Our understanding of primary (sensory) cilia has also expanded, and an ever-growing list of diverse conditions has been linked to defective function and signaling of the sensory cilium. Recent multicenter clinical and genetic studies have uncovered the heterogeneity of motile and sensory ciliopathies, and in some cases, the overlap between these conditions. Here, we will describe the genetics and pathophysiology of ciliopathies in children, focusing on PCD, review emerging genotype-phenotype relationships, and diagnostic tools available for the clinician.
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Affiliation(s)
- Amjad Horani
- a Department of Pediatrics , Washington University School of Medicine , St. Louis , MO , USA
| | - Thomas W Ferkol
- a Department of Pediatrics , Washington University School of Medicine , St. Louis , MO , USA.,b Department of Cell Biology and Physiology , Washington University School of Medicine , St. Louis , MO , USA
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33
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Jung B, Padula D, Burtscher I, Landerer C, Lutter D, Theis F, Messias AC, Geerlof A, Sattler M, Kremmer E, Boldt K, Ueffing M, Lickert H. Pitchfork and Gprasp2 Target Smoothened to the Primary Cilium for Hedgehog Pathway Activation. PLoS One 2016; 11:e0149477. [PMID: 26901434 PMCID: PMC4763541 DOI: 10.1371/journal.pone.0149477] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 01/31/2016] [Indexed: 01/14/2023] Open
Abstract
The seven-transmembrane receptor Smoothened (Smo) activates all Hedgehog (Hh) signaling by translocation into the primary cilia (PC), but how this is regulated is not well understood. Here we show that Pitchfork (Pifo) and the G protein-coupled receptor associated sorting protein 2 (Gprasp2) are essential components of an Hh induced ciliary targeting complex able to regulate Smo translocation to the PC. Depletion of Pifo or Gprasp2 leads to failure of Smo translocation to the PC and lack of Hh target gene activation. Together, our results identify a novel protein complex that is regulated by Hh signaling and required for Smo ciliary trafficking and Hh pathway activation.
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Affiliation(s)
- Bomi Jung
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Daniela Padula
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Ingo Burtscher
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Cedric Landerer
- Institute of Computational Biology, Helmholtz Zentrum München, München-Neuherberg, Germany
- Department of Ecology & Evolutionary Biology, University of Tennessee, Knoxville TN 37996, United States of America
| | - Dominik Lutter
- Institute of Computational Biology, Helmholtz Zentrum München, München-Neuherberg, Germany
- Institute of Diabetes and Adipositas, Helmholtz Zentrum München, München-Neuherberg, Germany
| | - Fabian Theis
- Institute of Computational Biology, Helmholtz Zentrum München, München-Neuherberg, Germany
| | - Ana C. Messias
- Institute of Structural Biology, Helmholtz Zentrum München, München-Neuherberg, Germany
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85747 Garching, Germany
| | - Arie Geerlof
- Institute of Structural Biology, Helmholtz Zentrum München, München-Neuherberg, Germany
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, München-Neuherberg, Germany
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, 85747 Garching, Germany
| | - Elisabeth Kremmer
- Institute of Molecular Immunology, Helmholtz Zentrum München, München-Neuherberg, Germany
| | - Karsten Boldt
- Department of Protein Science, Helmholtz Zentrum München, München-Neuherberg, Germany
- Centre of Ophthalmology, Institute for Ophthalmology Research, University of Tuebingen, 72076 Tuebingen, Germany
| | - Marius Ueffing
- Department of Protein Science, Helmholtz Zentrum München, München-Neuherberg, Germany
- Centre of Ophthalmology, Institute for Ophthalmology Research, University of Tuebingen, 72076 Tuebingen, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
- * E-mail:
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34
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Takao D, Verhey KJ. Gated entry into the ciliary compartment. Cell Mol Life Sci 2016; 73:119-27. [PMID: 26472341 PMCID: PMC4959937 DOI: 10.1007/s00018-015-2058-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 11/26/2022]
Abstract
Cilia and flagella play important roles in cell motility and cell signaling. These functions require that the cilium establishes and maintains a unique lipid and protein composition. Recent work indicates that a specialized region at the base of the cilium, the transition zone, serves as both a barrier to entry and a gate for passage of select components. For at least some cytosolic proteins, the barrier and gate functions are provided by a ciliary pore complex (CPC) that shares molecular and mechanistic properties with nuclear gating. Specifically, nucleoporins of the CPC limit the diffusional entry of cytosolic proteins in a size-dependent manner and enable the active transport of large molecules and complexes via targeting signals, importins, and the small G protein Ran. For membrane proteins, the septin protein SEPT2 is part of the barrier to entry whereas the gating function is carried out and/or regulated by proteins associated with ciliary diseases (ciliopathies) such as nephronophthisis, Meckel–Gruber syndrome and Joubert syndrome. Here, we discuss the evidence behind these models of ciliary gating as well as the similarities to and differences from nuclear gating.
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Affiliation(s)
- Daisuke Takao
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl, Ann Arbor, MI 48109 USA
| | - Kristen J. Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl, Ann Arbor, MI 48109 USA
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35
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Lechtreck KF. IFT-Cargo Interactions and Protein Transport in Cilia. Trends Biochem Sci 2015; 40:765-778. [PMID: 26498262 PMCID: PMC4661101 DOI: 10.1016/j.tibs.2015.09.003] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/07/2015] [Accepted: 09/11/2015] [Indexed: 12/30/2022]
Abstract
The motile and sensory functions of cilia and flagella are indispensable for human health. Cilia assembly requires a dedicated protein shuttle, intraflagellar transport (IFT), a bidirectional motility of multi-megadalton protein arrays along ciliary microtubules. IFT functions as a protein carrier delivering hundreds of distinct proteins into growing cilia. IFT-based protein import and export continue in fully grown cilia and are required for ciliary maintenance and sensing. Large ciliary building blocks might depend on IFT to move through the transition zone, which functions as a ciliary gate. Smaller, freely diffusing proteins, such as tubulin, depend on IFT to be concentrated or removed from cilia. As I discuss here, recent work provides insights into how IFT interacts with its cargoes and how the transport is regulated.
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Affiliation(s)
- Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, 635C Biological Science Building, 1000 Cedar Street, Athens, GA 30602, USA.
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36
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Nguyen AM, Young YN, Jacobs CR. The primary cilium is a self-adaptable, integrating nexus for mechanical stimuli and cellular signaling. Biol Open 2015; 4:1733-8. [PMID: 26603473 PMCID: PMC4736039 DOI: 10.1242/bio.014787] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mechanosensation is crucial for cells to sense and respond to mechanical signals within their local environment. While adaptation allows a sensor to be conditioned by stimuli within the environment and enables its operation in a wide range of stimuli intensities, the mechanisms behind adaptation remain controversial in even the most extensively studied mechanosensor, bacterial mechanosensitive channels. Primary cilia are ubiquitous sensory organelles. They have emerged as mechanosensors across diverse tissues, including kidney, liver and the embryonic node, and deflect with mechanical stimuli. Here, we show that both mechanical and chemical stimuli can alter cilium stiffness. We found that exposure to flow stiffens the cilium, which deflects less in response to subsequent exposures to flow. We also found that through a process involving acetylation, the cell can biochemically regulate cilium stiffness. Finally, we show that this altered stiffness directly affects the responsiveness of the cell to mechanical signals. These results demonstrate a potential mechanism through which the cell can regulate its mechanosensing apparatus.
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Affiliation(s)
- An M Nguyen
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA Runway Program, Jacobs Technion-Cornell Innovation Institute, Cornell Tech, New York, NY, 10011 USA
| | - Y-N Young
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ, 07102 USA
| | - Christopher R Jacobs
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
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37
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Patrussi L, Baldari CT. The Rab GTPase Rab8 as a shared regulator of ciliogenesis and immune synapse assembly: From a conserved pathway to diverse cellular structures. Small GTPases 2015; 7:16-20. [PMID: 26587735 DOI: 10.1080/21541248.2015.1111852] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Rab GTPases, which form the largest branch of the Ras GTPase superfamily, regulate almost every step of vesicle-mediated trafficking. Among them, Rab8 is an essential participant in primary cilium formation. In a report recently published in the Journal of Cell Science, Finetti and colleagues identify Rab8 as a novel player in vesicular traffic in the non-ciliated T lymphocytes, which contributes to the assembly of the specialized signaling platform known as the immune synapse. By interacting with the v-SNARE VAMP-3, Rab8 is indeed responsible for the final docking/fusion step in T cell receptor (TCR) recycling to the immune synapse. A second important take-home message which comes to light from this work is that VAMP-3 also interacts with Rab8 at the base of the cilium in NIH-3T3 cells, where it regulates ciliary growth and targeting of Smoothened at the plasma membrane. Hence the data presented in this report, in addition to identifying Rab8 as a novel player in vesicular traffic to the immune synapse, reveal how both ciliated and non-ciliated cells take advantage of a conserved pathway to build highly specific cellular structures.
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Affiliation(s)
- Laura Patrussi
- a Department of Life Sciences , University of Siena , Siena , Italy
| | - Cosima T Baldari
- a Department of Life Sciences , University of Siena , Siena , Italy
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38
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Jensen VL, Li C, Bowie RV, Clarke L, Mohan S, Blacque OE, Leroux MR. Formation of the transition zone by Mks5/Rpgrip1L establishes a ciliary zone of exclusion (CIZE) that compartmentalises ciliary signalling proteins and controls PIP2 ciliary abundance. EMBO J 2015; 34:2537-56. [PMID: 26392567 PMCID: PMC4609185 DOI: 10.15252/embj.201488044] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 08/22/2015] [Accepted: 08/26/2015] [Indexed: 01/09/2023] Open
Abstract
Cilia are thought to harbour a membrane diffusion barrier within their transition zone (TZ) that compartmentalises signalling proteins. How this "ciliary gate" assembles and functions remains largely unknown. Contrary to current models, we present evidence that Caenorhabditis elegans MKS-5 (orthologue of mammalian Mks5/Rpgrip1L/Nphp8 and Rpgrip1) may not be a simple structural scaffold for anchoring > 10 different proteins at the TZ, but instead, functions as an assembly factor. This activity is needed to form TZ ultrastructure, which comprises Y-shaped axoneme-to-membrane connectors. Coiled-coil and C2 domains within MKS-5 enable TZ localisation and functional interactions with two TZ modules, consisting of Meckel syndrome (MKS) and nephronophthisis (NPHP) proteins. Discrete roles for these modules at basal body-associated transition fibres and TZ explain their redundant functions in making essential membrane connections and thus sealing the ciliary compartment. Furthermore, MKS-5 establishes a ciliary zone of exclusion (CIZE) at the TZ that confines signalling proteins, including GPCRs and NPHP-2/inversin, to distal ciliary subdomains. The TZ/CIZE, potentially acting as a lipid gate, limits the abundance of the phosphoinositide PIP2 within cilia and is required for cell signalling. Together, our findings suggest a new model for Mks5/Rpgrip1L in TZ assembly and function that is essential for establishing the ciliary signalling compartment.
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Affiliation(s)
- Victor L Jensen
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC, Canada
| | - Chunmei Li
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC, Canada
| | - Rachel V Bowie
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Lara Clarke
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Swetha Mohan
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC, Canada
| | - Oliver E Blacque
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Michel R Leroux
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC, Canada
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39
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Laird JG, Pan Y, Modestou M, Yamaguchi DM, Song H, Sokolov M, Baker SA. Identification of a VxP Targeting Signal in the Flagellar Na+ /K+ -ATPase. Traffic 2015; 16:1239-53. [PMID: 26373354 DOI: 10.1111/tra.12332] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 09/11/2015] [Accepted: 09/11/2015] [Indexed: 12/15/2022]
Abstract
Na(+) /K(+) -ATPase (NKA) participates in setting electrochemical gradients, cardiotonic steroid signaling and cellular adhesion. Distinct isoforms of NKA are found in different tissues and subcellular localization patterns. For example, NKA α1 is widely expressed, NKA α3 is enriched in neurons and NKA α4 is a testes-specific isoform found in sperm flagella. In some tissues, ankyrin, a key component of the membrane cytoskeleton, can regulate the trafficking of NKA. In the retina, NKA and ankyrin-B are expressed in multiple cell types and immunostaining for each is striking in the synaptic layers. Labeling for NKA is also prominent along the inner segment plasma membrane (ISPM) of photoreceptors. NKA co-immunoprecipitates with ankyrin-B, but on a subcellular level colocalization of these two proteins varies dependent on the cell type. We used transgenic Xenopus laevis tadpoles to evaluate the subcellular trafficking of NKA in photoreceptors. GFP-NKA α3 and α1 are localized to the ISPM, but α4 is localized to outer segments (OSs). We identified a VxP motif responsible for the OS targeting by using a series of chimeric and mutant NKA constructs. This motif is similar to previously identified ciliary targeting motifs. Given the structural similarities between OSs and flagella, our findings shed light on the subcellular targeting of this testes-specific NKA isoform.
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Affiliation(s)
- Joseph G Laird
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Yuan Pan
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.,Current address: Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Modestos Modestou
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - David M Yamaguchi
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Hongman Song
- Department of Ophthalmology, West Virginia University School of Medicine and West Virginia University Eye Institute, Morgantown, WV, 26506, USA.,Current address: Section for Translational Research in Retina & Macular Degeneration, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD, 20892, USA
| | - Maxim Sokolov
- Department of Ophthalmology, West Virginia University School of Medicine and West Virginia University Eye Institute, Morgantown, WV, 26506, USA
| | - Sheila A Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
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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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Finetti F, Patrussi L, Galgano D, Cassioli C, Perinetti G, Pazour GJ, Baldari CT. The small GTPase Rab8 interacts with VAMP-3 to regulate the delivery of recycling T-cell receptors to the immune synapse. J Cell Sci 2015; 128:2541-52. [PMID: 26034069 DOI: 10.1242/jcs.171652] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 05/22/2015] [Indexed: 12/31/2022] Open
Abstract
IFT20, a component of the intraflagellar transport (IFT) system that controls ciliogenesis, regulates immune synapse assembly in the non-ciliated T-cell by promoting T-cell receptor (TCR) recycling. Here, we have addressed the role of Rab8 (for which there are two isoforms Rab8a and Rab8b), a small GTPase implicated in ciliogenesis, in TCR traffic to the immune synapse. We show that Rab8, which colocalizes with IFT20 in Rab11(+) endosomes, is required for TCR recycling. Interestingly, as opposed to in IFT20-deficient T-cells, TCR(+) endosomes polarized normally beneath the immune synapse membrane in the presence of dominant-negative Rab8, but were unable to undergo the final docking or fusion step. This could be accounted for by the inability of the vesicular (v)-SNARE VAMP-3 to cluster at the immune synapse in the absence of functional Rab8, which is responsible for its recruitment. Of note, and similar to in T-cells, VAMP-3 interacts with Rab8 at the base of the cilium in NIH-3T3 cells, where it regulates ciliary growth and targeting of the protein smoothened. The results identify Rab8 as a new player in vesicular traffic to the immune synapse and provide insight into the pathways co-opted by different cell types for immune synapse assembly and ciliogenesis.
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Affiliation(s)
- Francesca Finetti
- Department of Life Sciences, University of Siena, Siena 53100, Italy
| | - Laura Patrussi
- Department of Life Sciences, University of Siena, Siena 53100, Italy
| | - Donatella Galgano
- Department of Life Sciences, University of Siena, Siena 53100, Italy
| | - Chiara Cassioli
- Department of Life Sciences, University of Siena, Siena 53100, Italy
| | - Giuseppe Perinetti
- Department of Medical, Surgical and Health Sciences, School of Dentistry, University of Trieste, Trieste 34129, Italy
| | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Cosima T Baldari
- Department of Life Sciences, University of Siena, Siena 53100, Italy
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Wei Q, Ling K, Hu J. The essential roles of transition fibers in the context of cilia. Curr Opin Cell Biol 2015; 35:98-105. [PMID: 25988548 DOI: 10.1016/j.ceb.2015.04.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 04/18/2015] [Accepted: 04/23/2015] [Indexed: 12/18/2022]
Abstract
Once thought of as a vestigial organelle, the primary cilium is now recognized as a signaling hub for key cellular pathways in vertebrate development. The recent renaissance in cilia studies significantly improved our understanding of how cilia form and function, but little is known about how ciliogenesis is initiated and how ciliary proteins enter cilia. These important ciliary events require transition fibers (TFs) that are positioned at the ciliary base as symmetric nine-bladed propeller fibrous structures. Up until recently, TFs have been the most underappreciated ciliary structures due to limited knowledge about their molecular composition and function. Here, we highlight recent advances in our understanding of TF composition and the indispensable roles of TFs in regulating the initiation of ciliogenesis and the selective import of ciliary proteins.
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Affiliation(s)
- Qing Wei
- Department of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Kun Ling
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Jinghua Hu
- Department of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA; Mayo Translational PKD Center, Rochester, MN, USA; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA.
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Cao M, Ning J, Hernandez-Lara CI, Belzile O, Wang Q, Dutcher SK, Liu Y, Snell WJ. Uni-directional ciliary membrane protein trafficking by a cytoplasmic retrograde IFT motor and ciliary ectosome shedding. eLife 2015; 4. [PMID: 25688564 PMCID: PMC4362204 DOI: 10.7554/elife.05242] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 02/14/2015] [Indexed: 12/22/2022] Open
Abstract
The role of the primary cilium in key signaling pathways depends on dynamic regulation of ciliary membrane protein composition, yet we know little about the motors or membrane events that regulate ciliary membrane protein trafficking in existing organelles. Recently, we showed that cilium-generated signaling in Chlamydomonas induced rapid, anterograde IFT-independent, cytoplasmic microtubule-dependent redistribution of the membrane polypeptide, SAG1-C65, from the plasma membrane to the periciliary region and the ciliary membrane. Here, we report that the retrograde IFT motor, cytoplasmic dynein 1b, is required in the cytoplasm for this rapid redistribution. Furthermore, signaling-induced trafficking of SAG1-C65 into cilia is unidirectional and the entire complement of cellular SAG1-C65 is shed during signaling and can be recovered in the form of ciliary ectosomes that retain signal-inducing activity. Thus, during signaling, cells regulate ciliary membrane protein composition through cytoplasmic action of the retrograde IFT motor and shedding of ciliary ectosomes. DOI:http://dx.doi.org/10.7554/eLife.05242.001 Nearly every cell in the human body has slender, hair-like structures known as cilia that project outwards from its surface. These structures can sense and respond to light, chemicals and touch, and they are required for normal development. Failure of cilia to form or function in the correct manner can lead to severe diseases—such as kidney disorders, deafness and loss of vision. A major puzzle for researchers who study cilia has been to understand how cells change the composition of these structures as part of their response to a sensory input. Cilia are ancient structures that were present in early single-celled organisms and researchers interested in cilia have often used a single-celled green alga called Chlamydomonas reinhardtii as a model system for their studies. When these algae reproduce sexually, the two types of sex cells sense the presence of each other when their cilia touch and then stick together. This ciliary touching activates signals that are sent into the cells to get them ready to fuse together, much like sperm and egg cells do in animals. Both ciliary touching and signaling depend on a protein called SAG1, a part of which (known as SAG1-C65) is normally found mostly over the surface membrane of C. reinhardtii. Only very small amounts of SAG1-C65 are normally found on cilia; but, when the sex cells' cilia touch, this protein rapidly moves to the end of the cell nearest the cilia via a previously unknown mechanism. SAG1-C65 then becomes much more enriched in the cilia. Cao, Ning, Hernandez-Lara et al. investigated this process and found that SAG1-C65 movement requires a molecular motor called ‘cytoplasmic dynein’. This motor protein typically walks along the inside of cilia to transport other molecules away from the tip and towards the cell membrane. However, Cao, Ning, Hernandez-Lara et al. found that this dynein also carries SAG1-C65 from the membrane of the cells towards the base of the cilia in preparation for it to enter into these structures. As part of an effort to understand the fate of the protein after it entered cilia, Cao, Ning, Hernandez-Lara et al. discovered that the SAG1-C65 disappeared from the structures without returning to the cell membrane. Instead, SAG1-C65 was packaged within tiny bubble-like structures near the tips of cilia and these packages were then shed from cilia into the external environment. This discovery challenges a widely held view that proteins are only removed from cilia by returning to the cell. Future work will be required to understand more of the molecular details of these processes, which are likely to be present in most cells with cilia. DOI:http://dx.doi.org/10.7554/eLife.05242.002
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Affiliation(s)
- Muqing Cao
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jue Ning
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Carmen I Hernandez-Lara
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Olivier Belzile
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Qian Wang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Susan K Dutcher
- Department of Genetics, Washington University, St. Louis, United States
| | - Yanjie Liu
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - William J Snell
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
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Abstract
The centrosome and cilium are evolutionarily conserved components of the microtubule cytoskeleton, and act as a cellular signaling center that regulates the activity of numerous developmental signaling pathways. Several genetic syndromes, called the ciliopathies, are associated with defects in the structure or function of the centrosome-cilium complex. In the mammalian kidney, these organelles are found at the apical surface of renal epithelial cells lining the various segments of the nephron, where they relay information from the extracellular environment to the interior of the cell. Cilium-based signaling plays an important role in the development and homeostasis of mammalian kidneys, and ciliary dysfunction is implicated in the pathogenesis of cystic kidney disease. Given the importance of centrosomes and cilia in renal function, techniques used to visualize these organelles, analyze their composition, and test their functionality have become essential in many studies of kidney development and disease. Fluorescence microscopy is a powerful, widely used technique that has enhanced our understanding of molecular mechanisms that regulate the assembly, maintenance, and function of these organelles in various organs. Here, we present detailed steps for the isolation of kidneys from adult and embryonic mice, describe protocols to label centrosomes and cilia in renal tissues, and methods used to culture and image kidneys ex vivo.
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45
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Ciliary ectosomes: transmissions from the cell's antenna. Trends Cell Biol 2015; 25:276-85. [PMID: 25618328 DOI: 10.1016/j.tcb.2014.12.008] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/20/2014] [Accepted: 12/22/2014] [Indexed: 12/21/2022]
Abstract
The cilium is the site of function for a variety of membrane receptors, enzymes and signal transduction modules crucial for a spectrum of cellular processes. Through targeted transport and selective gating mechanisms, the cell localizes specific proteins to the cilium that equip it for the role of sensory antenna. This capacity of the cilium to serve as a specialized compartment where specific proteins can be readily concentrated for sensory reception also makes it an ideal organelle to employ for the regulated emission of specific biological material and information. In this review we present and discuss an emerging body of evidence centered on ciliary ectosomes - bioactive vesicles released from the surface of the cilium.
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Fu G, Nagasato C, Oka S, Cock JM, Motomura T. Proteomics analysis of heterogeneous flagella in brown algae (stramenopiles). Protist 2014; 165:662-75. [PMID: 25150613 DOI: 10.1016/j.protis.2014.07.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 07/22/2014] [Accepted: 07/22/2014] [Indexed: 10/25/2022]
Abstract
Flagella are conserved organelles among eukaryotes and they are composed of many proteins, which are necessary for flagellar assembly, maintenance and function. Stramenopiles, which include brown algae, diatoms and oomycetes, possess two laterally inserted flagella. The anterior flagellum (AF) extends forward and bears tripartite mastigonemes, whilst the smooth posterior flagellum (PF) often has a paraflagellar body structure. These heterogeneous flagella have served as crucial structures in algal studies especially from a viewpoint of phylogeny. However, the protein compositions of the flagella are still largely unknown. Here we report a LC-MS/MS based proteomics analysis of brown algal flagella. In total, 495 flagellar proteins were identified. Functional annotation of the proteome data revealed that brown algal flagellar proteins were associated with cell motility, signal transduction and various metabolic activities. We separately isolated AF and PF and analyzed their protein compositions. This analysis led to the identification of several AF- and PF-specific proteins. Among the PF-specific proteins, we found a candidate novel blue light receptor protein involved in phototaxis, and named it HELMCHROME because of the steering function of PF. Immunological analysis revealed that this protein was localized along the whole length of the PF and concentrated in the paraflagellar body.
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Affiliation(s)
- Gang Fu
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran 051-0013, Hokkaido, Japan
| | - Chikako Nagasato
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran 051-0013, Hokkaido, Japan
| | - Seiko Oka
- Instrumental Analysis Division, Equipment Management Center, Creative Research Institution, Hokkaido University, Sapporo 001-0021, Hokkaido, Japan
| | - J Mark Cock
- University Pierre et Marie Curie and Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, 29682 Roscoff Cedex, France
| | - Taizo Motomura
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran 051-0013, Hokkaido, Japan.
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Insect stage-specific receptor adenylate cyclases are localized to distinct subdomains of the Trypanosoma brucei Flagellar membrane. EUKARYOTIC CELL 2014; 13:1064-76. [PMID: 24879126 DOI: 10.1128/ec.00019-14] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Increasing evidence indicates that the Trypanosoma brucei flagellum (synonymous with cilium) plays important roles in host-parasite interactions. Several studies have identified virulence factors and signaling proteins in the flagellar membrane of bloodstream-stage T. brucei, but less is known about flagellar membrane proteins in procyclic, insect-stage parasites. Here we report on the identification of several receptor-type flagellar adenylate cyclases (ACs) that are specifically upregulated in procyclic T. brucei parasites. Identification of insect stage-specific ACs is novel, as previously studied ACs were constitutively expressed or confined to bloodstream-stage parasites. We show that procyclic stage-specific ACs are glycosylated, surface-exposed proteins that dimerize and possess catalytic activity. We used gene-specific tags to examine the distribution of individual AC isoforms. All ACs examined localized to the flagellum. Notably, however, while some ACs were distributed along the length of the flagellum, others specifically localized to the flagellum tip. These are the first transmembrane domain proteins to be localized specifically at the flagellum tip in T. brucei, emphasizing that the flagellum membrane is organized into specific subdomains. Deletion analysis reveals that C-terminal sequences are critical for targeting ACs to the flagellum, and sequence comparisons suggest that differential subflagellar localization might be specified by isoform-specific C termini. Our combined results suggest insect stage-specific roles for a subset of flagellar adenylate cyclases and support a microdomain model for flagellar cyclic AMP (cAMP) signaling in T. brucei. In this model, cAMP production is compartmentalized through differential localization of individual ACs, thereby allowing diverse cellular responses to be controlled by a common signaling molecule.
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48
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The primary cilium calcium channels and their role in flow sensing. Pflugers Arch 2014; 467:157-65. [PMID: 24764075 DOI: 10.1007/s00424-014-1516-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 04/06/2014] [Indexed: 12/20/2022]
Abstract
The primary cilium has been the focus of intense research since it was discovered that mutations in ciliary/basal body localized proteins give rise to a multitude of disorders. While these studies have revealed the contribution of this sensory organelle to multiple signalling pathways, little is known about how it actually mediates downstream events and why its loss causes disease states. Ciliopathies are linked to defects in either structure or function of cilia and are often associated with kidney cysts. The ciliopathy, autosomal dominant polycystic kidney disease (ADPKD), is caused by mutations to the PKD1 or PKD2 gene. The PKD gene products localize to the primary cilium, where they have been proposed to form a mechanosensory complex, sensitive to flow. Since mouse knockout models of Pkd1 or Pkd2 develop structurally normal cilia, it has been hypothesized that the loss of polycystins may lead to an impairment of flow sensing. Today, technically challenging patch clamp recordings of the primary cilium have become available, and the genetic relationship between polycystins (TRPPs) and the primary cilium has recently been dissected in detail.
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Ruppersburg CC, Hartzell HC. The Ca2+-activated Cl- channel ANO1/TMEM16A regulates primary ciliogenesis. Mol Biol Cell 2014; 25:1793-807. [PMID: 24694595 PMCID: PMC4038505 DOI: 10.1091/mbc.e13-10-0599] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ca2+-activated Cl− channel ANO1/TMEM16A is located in the primary cilium, and blocking it pharmacologically or knocking it down with shRNA interferes with ciliogenesis. Before ciliogenesis, the channel is organized into a torus-shaped structure (the “nimbus”) enriched in proteins required for ciliogenesis. Many cells possess a single, nonmotile, primary cilium highly enriched in receptors and sensory transduction machinery that plays crucial roles in cellular morphogenesis. Although sensory transduction requires ion channels, relatively little is known about ion channels in the primary cilium (with the exception of TRPP2). Here we show that the Ca2+-activated Cl− channel anoctamin-1 (ANO1/TMEM16A) is located in the primary cilium and that blocking its channel function pharmacologically or knocking it down with short hairpin RNA interferes with ciliogenesis. Before ciliogenesis, the channel becomes organized into a torus-shaped structure (“the nimbus”) enriched in proteins required for ciliogenesis, including the small GTPases Cdc42 and Arl13b and the exocyst complex component Sec6. The nimbus excludes F-actin and coincides with a ring of acetylated microtubules. The nimbus appears to form before, or independent of, apical docking of the mother centriole. Our data support a model in which the nimbus provides a scaffold for staging of ciliary components for assembly very early in ciliogenesis and chloride transport by ANO1/TMEM16A is required for the genesis or maintenance of primary cilia.
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Affiliation(s)
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
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50
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Diverse cell type-specific mechanisms localize G protein-coupled receptors to Caenorhabditis elegans sensory cilia. Genetics 2014; 197:667-84. [PMID: 24646679 DOI: 10.1534/genetics.114.161349] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The localization of signaling molecules such as G protein-coupled receptors (GPCRs) to primary cilia is essential for correct signal transduction. Detailed studies over the past decade have begun to elucidate the diverse sequences and trafficking mechanisms that sort and transport GPCRs to the ciliary compartment. However, a systematic analysis of the pathways required for ciliary targeting of multiple GPCRs in different cell types in vivo has not been reported. Here we describe the sequences and proteins required to localize GPCRs to the cilia of the AWB and ASK sensory neuron types in Caenorhabditis elegans. We find that GPCRs expressed in AWB or ASK utilize conserved and novel sequences for ciliary localization, and that the requirement for a ciliary targeting sequence in a given GPCR is different in different neuron types. Consistent with the presence of multiple ciliary targeting sequences, we identify diverse proteins required for ciliary localization of individual GPCRs in AWB and ASK. In particular, we show that the TUB-1 Tubby protein is required for ciliary localization of a subset of GPCRs, implying that defects in GPCR localization may be causal to the metabolic phenotypes of tub-1 mutants. Together, our results describe a remarkable complexity of mechanisms that act in a protein- and cell-specific manner to localize GPCRs to cilia, and suggest that this diversity allows for precise regulation of GPCR-mediated signaling as a function of external and internal context.
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