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Ewerling A, May-Simera HL. Evolutionary trajectory for nuclear functions of ciliary transport complex proteins. Microbiol Mol Biol Rev 2024:e0000624. [PMID: 38995044 DOI: 10.1128/mmbr.00006-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024] Open
Abstract
SUMMARYCilia and the nucleus were two defining features of the last eukaryotic common ancestor. In early eukaryotic evolution, these structures evolved through the diversification of a common membrane-coating ancestor, the protocoatomer. While in cilia, the descendants of this protein complex evolved into parts of the intraflagellar transport complexes and BBSome, the nucleus gained its selectivity by recruiting protocoatomer-like proteins to the nuclear envelope to form the selective nuclear pore complexes. Recent studies show a growing number of proteins shared between the proteomes of the respective organelles, and it is currently unknown how ciliary transport proteins could acquire nuclear functions and vice versa. The nuclear functions of ciliary proteins are still observable today and remain relevant for the understanding of the disease mechanisms behind ciliopathies. In this work, we review the evolutionary history of cilia and nucleus and their respective defining proteins and integrate current knowledge into theories for early eukaryotic evolution. We postulate a scenario where both compartments co-evolved and that fits current models of eukaryotic evolution, explaining how ciliary proteins and nucleoporins acquired their dual functions.
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Affiliation(s)
- Alexander Ewerling
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Helen Louise May-Simera
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
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2
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Zhong BH, Dong M. The implication of ciliary signaling pathways for epithelial-mesenchymal transition. Mol Cell Biochem 2024; 479:1535-1543. [PMID: 37490178 PMCID: PMC11224103 DOI: 10.1007/s11010-023-04817-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/15/2023] [Indexed: 07/26/2023]
Abstract
Epithelial-to-mesenchymal transition (EMT), which plays an essential role in development, tissue repair and fibrosis, and cancer progression, is a reversible cellular program that converts epithelial cells to mesenchymal cell states characterized by motility-invasive properties. The mostly signaling pathways that initiated and controlled the EMT program are regulated by a solitary, non-motile organelle named primary cilium. Acting as a signaling nexus, primary cilium dynamically concentrates signaling molecules to respond to extracellular cues. Recent research has provided direct evidence of connection between EMT and primary ciliogenesis in multiple contexts, but the mechanistic understanding of this relationship is complicated and still undergoing. In this review, we describe the current knowledge about the ciliary signaling pathways involved in EMT and list the direct evidence that shows the link between them, trying to figure out the intricate relationship between EMT and primary ciliogenesis, which may aid the future development of primary cilium as a novel therapeutic approach targeted to EMT.
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Affiliation(s)
- Bang-Hua Zhong
- Department of Gastrointestinal Surgery, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Ming Dong
- Department of Gastrointestinal Surgery, The First Hospital of China Medical University, Shenyang, Liaoning, China.
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3
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Horwitz A, Levi-Carmel N, Shnaider O, Birk R. BBS genes are involved in accelerated proliferation and early differentiation of BBS-related tissues. Differentiation 2024; 135:100745. [PMID: 38215537 DOI: 10.1016/j.diff.2024.100745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 01/01/2024] [Accepted: 01/02/2024] [Indexed: 01/14/2024]
Abstract
Bardet-Biedl syndrome (BBS) is an inherited disorder primarily ciliopathy with pleiotropic multi-systemic phenotypic involvement, including adipose, nerve, retinal, kidney, Etc. Consequently, it is characterized by obesity, cognitive impairment and retinal, kidney and cutaneous abnormalities. Initial studies, including ours have shown that BBS genes play a role in the early developmental stages of adipocytes and β-cells. However, this role in other BBS-related tissues is unknown. We investigated BBS genes involvement in the proliferation and early differentiation of different BBS cell types. The involvement of BBS genes in cellular proliferation were studied in seven in-vitro and transgenic cell models; keratinocytes (hHaCaT) and Ras-transfected keratinocytes (Ras-hHaCaT), neuronal cell lines (hSH-SY5Y and rPC-12), silenced BBS4 neural cell lines (siBbs4 hSH-SY5Y and siBbs4 rPC-12), adipocytes (m3T3L1), and ex-vivo transformed B-cells obtain from BBS4 patients, using molecular and biochemical methodologies. RashHaCaT cells showed an accelerated proliferation rate in parallel to significant reduction in the transcript levels of BBS1, 2, and 4. BBS1, 2, and 4 transcripts linked with hHaCaT cell cycle arrest (G1 phase) using both chemical (CDK4 inhibitor) and serum deprivation methodologies. Adipocyte (m3T3-L1) Bbs1, 2 and 4 transcript levels corresponded to the cell cycle phase (CDK4 inhibitor and serum deprivation). SiBBS4 hSH-SY5Y cells exhibited early cell proliferation and differentiation (wound healing assay) rates. SiBbs4 rPC-12 models exhibited significant proliferation and differentiation rate corresponding to Nestin expression levels. BBS4 patients-transformed B-cells exhibited an accelerated proliferation rate (LPS-induced methodology). In conclusions, the BBS4 gene plays a significant, similar and global role in the cellular proliferation of various BBS related tissues. These results highlight the universal role of the BBS gene in the cell cycle, and further deepen the knowledge of the mechanisms underlying the development of BBS.
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Affiliation(s)
- Avital Horwitz
- Nutrition Department, Health Sciences Faculty, Ariel University, Israel
| | | | - Olga Shnaider
- Nutrition Department, Health Sciences Faculty, Ariel University, Israel
| | - Ruth Birk
- Nutrition Department, Health Sciences Faculty, Ariel University, Israel.
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Kretschmer V, Schneider S, Matthiessen PA, Reichert D, Hotaling N, Glasßer G, Lieberwirth I, Bharti K, De Cegli R, Conte I, Nandrot EF, May-Simera HL. Deletion of IFT20 exclusively in the RPE ablates primary cilia and leads to retinal degeneration. PLoS Biol 2023; 21:e3002402. [PMID: 38048369 PMCID: PMC10721183 DOI: 10.1371/journal.pbio.3002402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 12/14/2023] [Accepted: 10/26/2023] [Indexed: 12/06/2023] Open
Abstract
Vision impairment places a serious burden on the aging society, affecting the lives of millions of people. Many retinal diseases are of genetic origin, of which over 50% are due to mutations in cilia-associated genes. Most research on retinal degeneration has focused on the ciliated photoreceptor cells of the retina. However, the contribution of primary cilia in other ocular cell types has largely been ignored. The retinal pigment epithelium (RPE) is a monolayer epithelium at the back of the eye intricately associated with photoreceptors and essential for visual function. It is already known that primary cilia in the RPE are critical for its development and maturation; however, it remains unclear whether this affects RPE function and retinal tissue homeostasis. We generated a conditional knockout mouse model, in which IFT20 is exclusively deleted in the RPE, ablating primary cilia. This leads to defective RPE function, followed by photoreceptor degeneration and, ultimately, vision impairment. Transcriptomic analysis offers insights into mechanisms underlying pathogenic changes, which include transcripts related to epithelial homeostasis, the visual cycle, and phagocytosis. Due to the loss of cilia exclusively in the RPE, this mouse model enables us to tease out the functional role of RPE cilia and their contribution to retinal degeneration, providing a powerful tool for basic and translational research in syndromic and non-syndromic retinal degeneration. Non-ciliary mechanisms of IFT20 in the RPE may also contribute to pathogenesis and cannot be excluded, especially considering the increasing evidence of non-ciliary functions of ciliary proteins.
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Affiliation(s)
- Viola Kretschmer
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Sandra Schneider
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Peter Andreas Matthiessen
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Dominik Reichert
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nathan Hotaling
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Gunnar Glasßer
- Max Planck Institute for Polymer Research, Mainz, Germany
| | | | - Kapil Bharti
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rossella De Cegli
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Ivan Conte
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
- University of Naples “Federico II”, Naples, Italy
| | | | - Helen Louise May-Simera
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
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5
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Freke GM, Martins T, Davies RJ, Beyer T, Seda M, Peskett E, Haq N, Prasai A, Otto G, Jeyabalan Srikaran J, Hernandez V, Diwan GD, Russell RB, Ueffing M, Huranova M, Boldt K, Beales PL, Jenkins D. De-Suppression of Mesenchymal Cell Identities and Variable Phenotypic Outcomes Associated with Knockout of Bbs1. Cells 2023; 12:2662. [PMID: 37998397 PMCID: PMC10670506 DOI: 10.3390/cells12222662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/25/2023] Open
Abstract
Bardet-Biedl syndrome (BBS) is an archetypal ciliopathy caused by dysfunction of primary cilia. BBS affects multiple tissues, including the kidney, eye and hypothalamic satiety response. Understanding pan-tissue mechanisms of pathogenesis versus those which are tissue-specific, as well as gauging their associated inter-individual variation owing to genetic background and stochastic processes, is of paramount importance in syndromology. The BBSome is a membrane-trafficking and intraflagellar transport (IFT) adaptor protein complex formed by eight BBS proteins, including BBS1, which is the most commonly mutated gene in BBS. To investigate disease pathogenesis, we generated a series of clonal renal collecting duct IMCD3 cell lines carrying defined biallelic nonsense or frameshift mutations in Bbs1, as well as a panel of matching wild-type CRISPR control clones. Using a phenotypic screen and an unbiased multi-omics approach, we note significant clonal variability for all assays, emphasising the importance of analysing panels of genetically defined clones. Our results suggest that BBS1 is required for the suppression of mesenchymal cell identities as the IMCD3 cell passage number increases. This was associated with a failure to express epithelial cell markers and tight junction formation, which was variable amongst clones. Transcriptomic analysis of hypothalamic preparations from BBS mutant mice, as well as BBS patient fibroblasts, suggested that dysregulation of epithelial-to-mesenchymal transition (EMT) genes is a general predisposing feature of BBS across tissues. Collectively, this work suggests that the dynamic stability of the BBSome is essential for the suppression of mesenchymal cell identities as epithelial cells differentiate.
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Affiliation(s)
- Grace Mercedes Freke
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Tiago Martins
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Rosalind Jane Davies
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Tina Beyer
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Elfriede-Aulhorn-Strasse 7, 72076 Tübingen, Germany; (T.B.); (M.U.); (K.B.)
| | - Marian Seda
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Emma Peskett
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Naila Haq
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Avishek Prasai
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic (M.H.)
| | - Georg Otto
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Jeshmi Jeyabalan Srikaran
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Victor Hernandez
- Life Sciences Department, CHMLS, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, UK;
| | - Gaurav D. Diwan
- BioQuant, University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; (G.D.D.); (R.B.R.)
- Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Robert B. Russell
- BioQuant, University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; (G.D.D.); (R.B.R.)
- Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Marius Ueffing
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Elfriede-Aulhorn-Strasse 7, 72076 Tübingen, Germany; (T.B.); (M.U.); (K.B.)
| | - Martina Huranova
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic (M.H.)
| | - Karsten Boldt
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Elfriede-Aulhorn-Strasse 7, 72076 Tübingen, Germany; (T.B.); (M.U.); (K.B.)
| | - Philip L. Beales
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
| | - Dagan Jenkins
- Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK; (G.M.F.); (T.M.); (M.S.); (E.P.); (N.H.); (G.O.); (J.J.S.); (P.L.B.)
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6
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Tian X, Zhao H, Zhou J. Organization, functions, and mechanisms of the BBSome in development, ciliopathies, and beyond. eLife 2023; 12:e87623. [PMID: 37466224 DOI: 10.7554/elife.87623] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 07/06/2023] [Indexed: 07/20/2023] Open
Abstract
The BBSome is an octameric protein complex that regulates ciliary transport and signaling. Mutations in BBSome subunits are closely associated with ciliary defects and lead to ciliopathies, notably Bardet-Biedl syndrome. Over the past few years, there has been significant progress in elucidating the molecular organization and functions of the BBSome complex. An improved understanding of BBSome-mediated biological events and molecular mechanisms is expected to help advance the development of diagnostic and therapeutic approaches for BBSome-related diseases. Here, we review the current literature on the structural assembly, transport regulation, and molecular functions of the BBSome, emphasizing its roles in cilium-related processes. We also provide perspectives on the pathological role of the BBSome in ciliopathies as well as how these can be exploited for therapeutic benefit.
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Affiliation(s)
- Xiaoyu Tian
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Huijie Zhao
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Jun Zhou
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, China
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, College of Life Sciences, Nankai University, Tianjin, China
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7
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Ewerling A, Maissl V, Wickstead B, May-Simera HL. Neofunctionalization of ciliary BBS proteins to nuclear roles is likely a frequent innovation across eukaryotes. iScience 2023; 26:106410. [PMID: 37034981 PMCID: PMC10074162 DOI: 10.1016/j.isci.2023.106410] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 07/20/2022] [Accepted: 03/10/2023] [Indexed: 03/17/2023] Open
Abstract
The eukaryotic BBSome is a transport complex within cilia and assembled by chaperonin-like BBS proteins. Recent work indicates nuclear functions for BBS proteins in mammals, but it is unclear how common these are in extant proteins or when they evolved. We screened for BBS orthologues across a diverse set of eukaryotes, consolidated nuclear association via signal sequence predictions and permutation analysis, and validated nuclear localization in mammalian cells via fractionation and immunocytochemistry. BBS proteins are-with exceptions-conserved as a set in ciliated species. Predictions highlight five most likely nuclear proteins and suggest that nuclear roles evolved independently of nuclear access during mitosis. Nuclear localization was confirmed in human cells. These findings suggest that nuclear BBS functions are potentially not restricted to mammals, but may be a common frequently co-opted eukaryotic feature. Understanding the functional spectrum of BBS proteins will help elucidating their role in gene regulation, development, and disease.
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Affiliation(s)
- Alexander Ewerling
- Institute of Molecular Physiology, Faculty of Biology, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Vanessa Maissl
- Institute of Molecular Physiology, Faculty of Biology, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Bill Wickstead
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Helen Louise May-Simera
- Institute of Molecular Physiology, Faculty of Biology, Johannes Gutenberg-University Mainz, Mainz, Germany
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Morleo M, Pezzella N, Franco B. Proteome balance in ciliopathies: the OFD1 protein example. Trends Mol Med 2023; 29:201-217. [PMID: 36494254 DOI: 10.1016/j.molmed.2022.11.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 11/04/2022] [Accepted: 11/18/2022] [Indexed: 12/12/2022]
Abstract
The balance of protein synthesis and degradation is finely regulated and influences cellular homeostasis and biological processes (e.g., embryonic development and neuronal plasticity). Recent data demonstrated that centrosomal/ciliary proteins enable proteome control in response to spatial or microenvironmental stimuli. Here, we discuss recent discoveries regarding the role in the balance of the proteome of centrosomal/ciliary proteins associated with genetic disorders known as ciliopathies. In particular, OFD1 was the first example of a ciliopathy protein controlling both protein expression and autophagic/proteasomal degradation. Understanding the role of proteome balance in the pathogenesis of the clinical manifestations of ciliopathies may pave the way to the identification of a wide range of putative novel therapeutic targets for these conditions.
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Affiliation(s)
- Manuela Morleo
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Naples, Italy; Department of Precision Medicine, University of Campania 'Luigi Vanvitelli', Naples, Italy
| | - Nunziana Pezzella
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Naples, Italy; Scuola Superiore Meridionale (SSM, School of Advanced Studies), Genomics and Experimental Medicine program, University of Naples Federico II, Naples, Italy
| | - Brunella Franco
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Naples, Italy; Scuola Superiore Meridionale (SSM, School of Advanced Studies), Genomics and Experimental Medicine program, University of Naples Federico II, Naples, Italy; Medical Genetics, Department of Translational Medicine, University of Naples 'Federico II', Via Sergio Pansini, 80131, Naples, Italy.
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9
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Melluso A, Secondulfo F, Capolongo G, Capasso G, Zacchia M. Bardet-Biedl Syndrome: Current Perspectives and Clinical Outlook. Ther Clin Risk Manag 2023; 19:115-132. [PMID: 36741589 PMCID: PMC9896974 DOI: 10.2147/tcrm.s338653] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/20/2023] [Indexed: 02/04/2023] Open
Abstract
The Bardet Biedl syndrome (BBS) is a rare inherited disorder considered a model of non-motile ciliopathy. It is in fact caused by mutations of genes encoding for proteins mainly localized to the base of the cilium. Clinical features of BBS patients are widely shared with patients suffering from other ciliopathies, especially autosomal recessive syndromic disorders; moreover, mutations in cilia-related genes can cause different clinical ciliopathy entities. Besides the best-known clinical features, as retinal degeneration, learning disabilities, polydactyly, obesity and renal defects, several additional clinical signs have been reported in BBS, expanding our understanding of the complexity of its clinical spectrum. The present review aims to describe the current knowledge of BBS i) pathophysiology, ii) clinical manifestations, highlighting both the most common and the less described features, iii) current and future perspective for treatment.
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Affiliation(s)
- Andrea Melluso
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Floriana Secondulfo
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Giovanna Capolongo
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Giovambattista Capasso
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy,Biogem Scarl, Ariano Irpino, AV, 83031, Italy
| | - Miriam Zacchia
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy,Correspondence: Miriam Zacchia, Via Pansini 5, Naples, 80131, Italy, Tel +39 081 566 6650, Fax +39 081 566 6671, Email
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10
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Solarat C, Valverde D. Clinical and molecular diagnosis of Bardet-Biedl syndrome (BBS). Methods Cell Biol 2023; 176:125-137. [PMID: 37164534 DOI: 10.1016/bs.mcb.2022.12.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Bardet-Biedl syndrome (BBS) is a rare genetic disease of the group of ciliopathies, a group of pathologies characterized mainly by defects in the structure and/or function of primary cilia. The main features of this ciliopathy are retinal dystrophy, obesity, polydactyly, urogenital and renal abnormalities, and cognitive impairment, commonly accompanied by various secondary features, making clear the extensive clinical heterogeneity associated with this syndrome, which, together with the frequent overlapping phenotype with other ciliopathies, greatly complicates its diagnosis. Patients are mainly detected by their pediatrician at quite early ages, usually between 2 and 6years. The pediatrician, given the main symptoms they present, usually refers patients to a specialist. Personalized medicine brought diagnosis closer to many patients who lacked it. It usually presents an autosomal recessive mode of inheritance, but in recent years several authors have proposed more complex inheritance models to explain the frequent inter- and intra-familial clinical variability. The main molecular techniques used for diagnosis are gene panels, the clinical exome and, in certain cases, the patient's complete genome. Although numerous studies have contributed to defining the role of the different BBS genes and designing various strategies for the molecular diagnosis of BBS, as well as delving into the functions performed by these proteins, these advances have not been sufficient to develop a complete treatment for this syndrome. and to be able to offer patients some therapeutic options.
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Zhuo R, Zhang Z, Guo X, Cao H, Chen Y, Tao Y, Yang R, Li X, Pan J, Wang J. Super-enhancer-associated TTC8 alters the nucleocytoplasmic distribution of PHOX2B and activates MAPK signaling in neuroblastoma. Genes Dis 2022. [DOI: 10.1016/j.gendis.2022.07.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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12
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Loss of the Bardet-Biedl protein Bbs1 alters photoreceptor outer segment protein and lipid composition. Nat Commun 2022; 13:1282. [PMID: 35277505 PMCID: PMC8917222 DOI: 10.1038/s41467-022-28982-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 02/23/2022] [Indexed: 12/22/2022] Open
Abstract
Primary cilia are key sensory organelles whose dysfunction leads to ciliopathy disorders such as Bardet-Biedl syndrome (BBS). Retinal degeneration is common in ciliopathies, since the outer segments (OSs) of photoreceptors are highly specialized primary cilia. BBS1, encoded by the most commonly mutated BBS-associated gene, is part of the BBSome protein complex. Using a bbs1 zebrafish mutant, we show that retinal development and photoreceptor differentiation are unaffected by Bbs1-loss, supported by an initially unaffected transcriptome. Quantitative proteomics and lipidomics on samples enriched for isolated OSs show that Bbs1 is required for BBSome-complex stability and that Bbs1-loss leads to accumulation of membrane-associated proteins in OSs, with enrichment in proteins involved in lipid homeostasis. Disruption of the tightly regulated OS lipid composition with increased OS cholesterol content are paralleled by early functional visual deficits, which precede progressive OS morphological anomalies. Our findings identify a role for Bbs1/BBSome in OS lipid homeostasis, suggesting a pathomechanism underlying retinal degeneration in BBS. Primary cilia are key sensory organelles whose dysfunction leads to ciliopathy disorders such as Bardet-Biedl syndrome (BBS). Here they identify a role for Bbs1 in lipid homeostasis of photoreceptor outer segments in zebrafish, which may contribute to vision loss in patients with Bardet-Biedl syndrome.
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Gupta N, D'Acierno M, Zona E, Capasso G, Zacchia M. Bardet-Biedl syndrome: The pleiotropic role of the chaperonin-like BBS6, 10, and 12 proteins. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:9-19. [PMID: 35373910 PMCID: PMC9325507 DOI: 10.1002/ajmg.c.31970] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 02/08/2022] [Accepted: 03/27/2022] [Indexed: 12/11/2022]
Abstract
Bardet–Biedl syndrome (BBS) is a rare pleiotropic disorder known as a ciliopathy. Despite significant genetic heterogeneity, BBS1 and BBS10 are responsible for major diagnosis in western countries. It is well established that eight BBS proteins, namely BBS1, 2, 4, 5, 7, 8, 9, and 18, form the BBSome, a multiprotein complex serving as a regulator of ciliary membrane protein composition. Less information is available for BBS6, BBS10, and BBS12, three proteins showing sequence homology with the CCT/TRiC family of group II chaperonins. Even though their chaperonin function is debated, scientific evidence demonstrated that they are required for initial BBSome assembly in vitro. Recent studies suggest that genotype may partially predict clinical outcomes. Indeed, patients carrying truncating mutations in any gene show the most severe phenotype; moreover, mutations in chaperonin‐like BBS proteins correlated with severe kidney impairment. This study is a critical review of the literature on genetics, expression level, cellular localization and function of BBS proteins, focusing primarily on the chaperonin‐like BBS proteins, and aiming to provide some clues to understand the pathomechanisms of disease in this setting.
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Affiliation(s)
- Neha Gupta
- Unit of Nephrology, Department of Translational Medical Sciences, University of Campania L. Vanvitelli, Naples, Italy.,BioGem S.C.A.R.L., Benevento, Benevento Province, Italy
| | - Mariavittoria D'Acierno
- Unit of Nephrology, Department of Translational Medical Sciences, University of Campania L. Vanvitelli, Naples, Italy.,BioGem S.C.A.R.L., Benevento, Benevento Province, Italy
| | - Enrica Zona
- Unit of Nephrology, Department of Translational Medical Sciences, University of Campania L. Vanvitelli, Naples, Italy
| | | | - Miriam Zacchia
- Unit of Nephrology, Department of Translational Medical Sciences, University of Campania L. Vanvitelli, Naples, Italy
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14
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Abstract
The BBSome is an octameric protein complex involved in Bardet-Biedl syndrome (BBS), a human pleiotropic, autosomal recessive condition. Patients with BBS display various clinical features including obesity, hypertension, and renal abnormalities. Association studies have also linked the BBS genes to hypertension and other cardiovascular risks in the general population. The BBSome was originally associated with the function of cilia, a highly specialized organelle that extend from the cell membrane of most vertebrate cells. However, subsequent studies have implicated the BBSome in the control of a myriad of other cellular processes not related to cilia including cell membrane localization of receptors and gene expression. The development of animal models of BBS such as mouse lines lacking various components of the BBSome and associated proteins has facilitated studying their role in the control of cardiovascular function and deciphering the pathophysiological mechanisms responsible for the cardiovascular aberrations associated with BBS. These studies revealed the importance of the neuronal, renal, vascular, and cardiac BBSome in the regulation of blood pressure, renal function, vascular reactivity, and cardiac development. The BBSome has also emerged as a critical regulator of key systems involved in cardiovascular control including the renin-angiotensin system. Better understanding of the influence of the BBSome on the molecular and physiological processes relevant to cardiovascular health and disease has the potential of identifying novel mechanisms underlying hypertension and other cardiovascular risks.
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Affiliation(s)
- Yuying Zhao
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, USA,Human Toxicology Graduate Program, University of Iowa Graduate College, Iowa City, IA, USA
| | - Kamal Rahmouni
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, USA,Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, USA,Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, IA, USA,Obesity Research and Educational Initiative, University of Iowa Carver College of Medicine, Iowa City, IA, USA,Iowa City VA Health Care System, Iowa City, IA, USA,Corresponding author: Kamal Rahmouni, Ph.D., Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA, , Tel: 319 353 5256, Fax: 319 353 5350
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15
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Eintracht J, Forsythe E, May-Simera H, Moosajee M. Translational readthrough of ciliopathy genes BBS2 and ALMS1 restores protein, ciliogenesis and function in patient fibroblasts. EBioMedicine 2021; 70:103515. [PMID: 34365092 PMCID: PMC8353411 DOI: 10.1016/j.ebiom.2021.103515] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/13/2021] [Accepted: 07/19/2021] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Ciliary dysfunction underlies a range of genetic disorders collectively termed ciliopathies, for which there are no treatments available. Bardet-Biedl syndrome (BBS) is characterised by multisystemic involvement, including rod-cone dystrophy and renal abnormalities. Together with Alström syndrome (AS), they are known as the 'obesity ciliopathies' due to their common phenotype. Nonsense mutations are responsible for approximately 11% and 40% of BBS and AS cases, respectively. Translational readthrough inducing drugs (TRIDs) can restore full-length protein bypassing in-frame premature termination codons, and are a potential therapeutic approach for nonsense-mediated ciliopathies. METHODS Patient fibroblasts harbouring nonsense mutations from two different ciliopathies (Bardet-Biedl Syndrome and Alström Syndrome) were treated with PTC124 (ataluren) or amlexanox. Following treatment, gene expression, protein levels and ciliogenesis were evaluated. The expression of intraflagellar transport protein IFT88 and G-protein coupled receptor SSTR3 was investigated as a readout of ciliary function. FINDINGS mRNA expression was significantly increased in amlexanox-treated patient fibroblasts, and full-length BBS2 or ALMS1 protein expression was restored in PTC124- and amlexanox-treated fibroblasts. Treatment with TRIDs significantly improved ciliogenesis defects in BBS2Y24*/R275* fibroblasts. Treatment recovered IFT88 expression and corrected SSTR3 mislocalisation in BBS2Y24*/R275* and ALMS1S1645*/S1645* fibroblasts, suggesting rescue of ciliary function. INTERPRETATION The recovery of full-length BBS2 and ALMS1 expression and correction of anatomical and functional ciliary defects in BBS2Y24*/R275* and ALMS1S1645*/S1645* fibroblasts suggest TRIDs are a potential therapeutic option for the treatment of nonsense-mediated ciliopathies. FUNDING Wellcome Trust 205174/Z/16/Z, National Centre for the Replacement, Refinement & Reduction of Animals in Research. Deutsche Forschungsgemeinschaft SPP2127 (DFG Grant MA 6139/3-1).
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Affiliation(s)
| | - Elizabeth Forsythe
- Clinical Genetics Unit, Great Ormond Street Hospital; Genetics and Genomic Medicine Programme, Great Ormond Street Institute of Child Health
| | - Helen May-Simera
- Institute of Molecular Physiology, Johannes Gutenburg University, Mainz
| | - Mariya Moosajee
- UCL Institute of Ophthalmology, London, United Kingdom; The Francis Crick Institute, London, United Kingdom; Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom; Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom.
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16
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Yildirim A, Mozaffari-Jovin S, Wallisch AK, Schäfer J, Ludwig SEJ, Urlaub H, Lührmann R, Wolfrum U. SANS (USH1G) regulates pre-mRNA splicing by mediating the intra-nuclear transfer of tri-snRNP complexes. Nucleic Acids Res 2021; 49:5845-5866. [PMID: 34023904 PMCID: PMC8191790 DOI: 10.1093/nar/gkab386] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/22/2021] [Accepted: 04/28/2021] [Indexed: 02/06/2023] Open
Abstract
Splicing is catalyzed by the spliceosome, a compositionally dynamic complex assembled stepwise on pre-mRNA. We reveal links between splicing machinery components and the intrinsically disordered ciliopathy protein SANS. Pathogenic mutations in SANS/USH1G lead to Usher syndrome—the most common cause of deaf-blindness. Previously, SANS was shown to function only in the cytosol and primary cilia. Here, we have uncovered molecular links between SANS and pre-mRNA splicing catalyzed by the spliceosome in the nucleus. We show that SANS is found in Cajal bodies and nuclear speckles, where it interacts with components of spliceosomal sub-complexes such as SF3B1 and the large splicing cofactor SON but also with PRPFs and snRNAs related to the tri-snRNP complex. SANS is required for the transfer of tri-snRNPs between Cajal bodies and nuclear speckles for spliceosome assembly and may also participate in snRNP recycling back to Cajal bodies. SANS depletion alters the kinetics of spliceosome assembly, leading to accumulation of complex A. SANS deficiency and USH1G pathogenic mutations affects splicing of genes related to cell proliferation and human Usher syndrome. Thus, we provide the first evidence that splicing dysregulation may participate in the pathophysiology of Usher syndrome.
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Affiliation(s)
- Adem Yildirim
- Molecular Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Germany
| | - Sina Mozaffari-Jovin
- Department of Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Goettingen, Germany.,Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.,Bioanalytical Mass Spectrometry, Max-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Ann-Kathrin Wallisch
- Molecular Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Germany
| | - Jessica Schäfer
- Molecular Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Germany
| | - Sebastian E J Ludwig
- Department of Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max-Planck-Institute for Biophysical Chemistry, Goettingen, Germany.,Bioanalytics, Department of Clinical Chemistry, University Medical Center Goettingen, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
| | - Uwe Wolfrum
- Molecular Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Germany
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17
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Schneider S, De Cegli R, Nagarajan J, Kretschmer V, Matthiessen PA, Intartaglia D, Hotaling N, Ueffing M, Boldt K, Conte I, May-Simera HL. Loss of Ciliary Gene Bbs8 Results in Physiological Defects in the Retinal Pigment Epithelium. Front Cell Dev Biol 2021; 9:607121. [PMID: 33681195 PMCID: PMC7930748 DOI: 10.3389/fcell.2021.607121] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 01/12/2021] [Indexed: 11/17/2022] Open
Abstract
Primary cilia are sensory organelles vital for developmental and physiological processes. Their dysfunction causes a range of phenotypes including retinopathies. Although primary cilia have been described in the retinal pigment epithelium (RPE), little is known about their contribution to biological processes within this tissue. Ciliary proteins are increasingly being identified in non-ciliary locations and might carry out additional functions, disruption of which possibly contributes to pathology. The RPE is essential for maintaining photoreceptor cells and visual function. We demonstrate that upon loss of Bbs8, predominantly thought to be a ciliary gene, the RPE shows changes in gene and protein expression initially involved in signaling pathways and developmental processes, and at a later time point RPE homeostasis and function. Differentially regulated molecules affecting the cytoskeleton and cellular adhesion, led to defective cellular polarization and morphology associated with a possible epithelial-to-mesenchymal transition (EMT)-like phenotype. Our data highlights the benefit of combinatorial “omics” approaches with in vivo data for investigating the function of ciliopathy proteins. It also emphasizes the importance of ciliary proteins in the RPE and their contribution to visual disorders, which must be considered when designing treatment strategies for retinal degeneration.
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Affiliation(s)
- Sandra Schneider
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | | | - Jayapriya Nagarajan
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, United States
| | - Viola Kretschmer
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Peter Andreas Matthiessen
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | | | - Nathan Hotaling
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, United States
| | - Marius Ueffing
- Medical Bioanalytics, Institute for Ophthalmic Research, Eberhard-Karls University, Tübingen, Germany
| | - Karsten Boldt
- Medical Bioanalytics, Institute for Ophthalmic Research, Eberhard-Karls University, Tübingen, Germany
| | - Ivan Conte
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy.,Department of Biology, University of Naples Federico II, Naples, Italy
| | - Helen Louise May-Simera
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
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18
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Zhang CJ, Xiang L, Chen XJ, Wang XY, Wu KC, Zhang BW, Chen DF, Jin GH, Zhang H, Chen YC, Liu WQ, Li ML, Ma Y, Jin ZB. Ablation of Mature miR-183 Leads to Retinal Dysfunction in Mice. Invest Ophthalmol Vis Sci 2020; 61:12. [PMID: 32176259 PMCID: PMC7401733 DOI: 10.1167/iovs.61.3.12] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Purpose The microRNA cluster miR-183C, which includes miR-183 and two other genes, is critical for multiple sensory systems. In mouse retina, removal of this cluster results in photoreceptor defects in polarization, phototransduction, and outer segment elongation. However, the individual roles of the three components of this cluster are not clearly known. We studied the separate role of mouse miR-183 in in vivo. Methods miR-183 knockout mice were generated using the CRISPR/Cas9 genome-editing system. Electroretinography were carried out to investigate the changes of retinal structures and function. miR-183 was overexpressed by subretinal adeno-associated virus (AAV) injection in vivo. Rnf217, a target of miR-183 was overexpressed by cell transfection of the photoreceptor-derived cell line 661W in vitro. RNA sequencing and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to compare the gene expression changes in AAV-injected mice and transfected cells. Results The miR-183 knockout mice showed progressively attenuated electroretinogram responses. Over- or under-expression of Rnf217, a direct target of miR-183, misregulated expression of cilia-related BBSome genes. Rnf217 overexpression also led to compromised electroretinography responses in WT mice, indicating that it may contribute to functional abnormalities in miR-183 knockout mice. Conclusions miR-183 is essential for mouse retinal function mediated directly and indirectly through Rnf217 and cilia-related genes. Our findings provide valuable insights into the explanation and analysis of the regulatory role of the individual miR-183 in miR-183C.
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19
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Exploring Key Challenges of Understanding the Pathogenesis of Kidney Disease in Bardet-Biedl Syndrome. Kidney Int Rep 2020; 5:1403-1415. [PMID: 32954066 PMCID: PMC7486190 DOI: 10.1016/j.ekir.2020.06.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/04/2020] [Accepted: 06/17/2020] [Indexed: 12/21/2022] Open
Abstract
Bardet–Biedl syndrome (BBS) is a rare pleiotropic inherited disorder known as a ciliopathy. Kidney disease is a cardinal clinical feature; however, it is one of the less investigated traits. This study is a comprehensive analysis of the literature aiming to collect available information providing mechanistic insights into the pathogenesis of kidney disease by analyzing clinical and basic science studies focused on this issue. The analysis revealed that the syndrome is either clinically and genetically heterogenous, with 24 genes discovered to date, but with 3 genes (BBS1, BBS2, and BBS10) accounting for almost 50% of diagnoses; genotype–phenotype correlation studies showed that patients with BBS1 mutations have a less severe renal phenotype than the other 2 most common loci; in addition, truncating rather than missense mutations are more likely to cause kidney disease. However, significant intrafamilial clinical variability has been described, with no clear explanation to date. In mice kidneys, Bbs genes have relative low expression levels, in contrast with other common affected organs, like the retina; surprisingly, Bbs1 is the only locus with basal overexpression in the kidney. In vitro studies indicate that signalling pathways involved in embryonic kidney development and repair are affected in the context of BBS depletion; in mice, kidney disease does not have a full penetrance; when present, it resembles human phenotype and shows an age-dependent progression. Data on the exact contribution of local versus systemic consequences of Bbs dysfunction are scanty and further investigations are required to get firm conclusions.
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Peixoto E, Richard S, Pant K, Biswas A, Gradilone SA. The primary cilium: Its role as a tumor suppressor organelle. Biochem Pharmacol 2020; 175:113906. [PMID: 32169416 DOI: 10.1016/j.bcp.2020.113906] [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] [Received: 01/22/2020] [Accepted: 03/06/2020] [Indexed: 02/08/2023]
Abstract
The primary cilium is an organelle that nearly all cells within the body contain. Its function is to sense the extracellular environment through its abundance of receptors and linked signaling pathways, working as an antenna. Ciliary defects lead to different pathologies. In particular, many tumors lose primary cilia, and this is linked with negative implications for the cell such as an increase in malignancy. In this work we will go through the knowledge of the role of primary cilia in normal conditions, how it is involved in diverse signaling pathways, and in disease, particularly in cancer, highlighting its tumor suppressor properties.
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Affiliation(s)
- Estanislao Peixoto
- The Hormel Institute, University of Minnesota, Austin, MN, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Seth Richard
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Kishor Pant
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Aalekhya Biswas
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Sergio A Gradilone
- The Hormel Institute, University of Minnesota, Austin, MN, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
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21
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Abstract
The BBSome, a complex of 8 BBS (Bardet-Biedl syndrome) proteins known for its role in the control of cilia function and other cellular processes, has been implicated in blood pressure control, but the underlying mechanisms are not fully understood. Here, we show that neuronal BBSome plays an important role in blood pressure regulation. Targeted inactivation of the BBSome in the nervous system through Bbs1 gene deletion causes sympathetically mediated increase in blood pressure in mice. This phenotype is reproduced by selective ablation of the Bbs1 gene from the LRb (leptin receptor)-expressing neurons. Strikingly, the well-known role of the BBSome in the regulation of cilia formation and function is unlikely to account for the prohypertensive effect of BBSome inactivation as disruption of the IFT (intraflagellar transport) machinery required for ciliogenesis by deleting the Ift88 gene in LRb neurons had no effect on arterial pressure and sympathetic nerve activity. Furthermore, we found that Bbs1 gene deletion from AgRP (agouti-related protein) neurons or POMC (proopiomelanocortin) neurons increased renal and splanchnic sympathetic nerve activity without altering blood pressure. This lack of blood pressure increase despite the sympathetic overdrive may be explained by vascular adrenergic desensitization as indicated by the reduced vascular contractile response evoked by phenylephrine and the decreased expression of adrenergic receptors. Our results identify the neuronal BBSome as a new player in hemodynamic, sympathetic, and vascular regulation, in a manner independent of cilia.
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Affiliation(s)
- Deng-Fu Guo
- From the Department of Neuroscience and Pharmacology (D.-F.G., J.J.R., D.A.M., K.R.), University of Iowa Carver College of Medicine, Iowa City
| | - John J Reho
- From the Department of Neuroscience and Pharmacology (D.-F.G., J.J.R., D.A.M., K.R.), University of Iowa Carver College of Medicine, Iowa City
| | - Donald A Morgan
- From the Department of Neuroscience and Pharmacology (D.-F.G., J.J.R., D.A.M., K.R.), University of Iowa Carver College of Medicine, Iowa City
| | - Kamal Rahmouni
- From the Department of Neuroscience and Pharmacology (D.-F.G., J.J.R., D.A.M., K.R.), University of Iowa Carver College of Medicine, Iowa City.,Department of Internal Medicine (K.R.), University of Iowa Carver College of Medicine, Iowa City.,Obesity Research and Education Initiative (K.R.), University of Iowa Carver College of Medicine, Iowa City.,Fraternal Order of Eagles Diabetes Research Center (K.R.), University of Iowa Carver College of Medicine, Iowa City.,Iowa Neuroscience Institute (K.R.), University of Iowa Carver College of Medicine, Iowa City.,Veterans Affairs Health Care System, Iowa City (K.R.)
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22
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Patnaik SR, Farag A, Brücker L, Volz AK, Schneider S, Kretschmer V, May-Simera HL. Tissue-dependent differences in Bardet-Biedl syndrome gene expression. Biol Cell 2020; 112:39-52. [PMID: 31845361 DOI: 10.1111/boc.201900077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/20/2019] [Accepted: 11/28/2019] [Indexed: 12/24/2022]
Abstract
BACKGROUND INFORMATION Primary cilia are highly conserved multifunctional cell organelles that extend from the cell membrane. A range of genetic disorders, collectively termed ciliopathies, is attributed to primary cilia dysfunction. The archetypical ciliopathy is the Bardet-Biedl syndrome (BBS), patients of which display virtually all symptoms associated with dysfunctional cilia. The primary cilium acts as a sensory organelle transmitting intra- and extracellular signals thereby transducing various signalling pathways facilitated by the BBS proteins. Growing evidence suggests that cilia proteins also have alternative functions in ciliary independent mechanisms, which might be contributing to disease etiology. RESULTS In an attempt to gain more insight into possible differences in organ specific roles, we examined whether relative gene expression for individual Bbs genes was constant across different tissues in mouse, in order to distinguish possible differences in organ specific roles. All tested tissues show differentially expressed Bbs transcripts with some tissues showing a more similar stoichiometric composition of transcripts than others do. However, loss of Bbs6 or Bbs8 affects expression of other Bbs transcripts in a tissue-dependent way. CONCLUSIONS AND SIGNIFICANCE Our data support the hypothesis that in some organs, BBS proteins not only function in a complex but might also have alternative functions in a ciliary independent context. This significantly alters our understanding of disease pathogenesis and development of possible treatment strategies.
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Affiliation(s)
- Sarita Rani Patnaik
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, 55128, Germany
| | - Aalaa Farag
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, 55128, Germany
| | - Lena Brücker
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, 55128, Germany
| | - Ann-Kathrin Volz
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, 55128, Germany
| | - Sandra Schneider
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, 55128, Germany
| | - Viola Kretschmer
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, 55128, Germany
| | - Helen Louise May-Simera
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, 55128, Germany
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23
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Functional analysis of new human Bardet-Biedl syndrome loci specific variants in the zebrafish model. Sci Rep 2019; 9:12936. [PMID: 31506453 PMCID: PMC6736949 DOI: 10.1038/s41598-019-49217-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 08/16/2019] [Indexed: 11/09/2022] Open
Abstract
The multiple genetic approaches available for molecular diagnosis of human diseases have made possible to identify an increasing number of pathogenic genetic changes, particularly with the advent of next generation sequencing (NGS) technologies. However, the main challenge lies in the interpretation of their functional impact, which has resulted in the widespread use of animal models. We describe here the functional modelling of seven BBS loci variants, most of them novel, in zebrafish embryos to validate their in silico prediction of pathogenicity. We show that target knockdown (KD) of known BBS (BBS1, BB5 or BBS6) loci leads to developmental defects commonly associated with ciliopathies, as previously described. These KD pleiotropic phenotypes were rescued by co-injecting human wild type (WT) loci sequence but not with the equivalent mutated mRNAs, providing evidence of the pathogenic effect of these BBS changes. Furthermore, direct assessment of cilia located in Kupffer's vesicle (KV) showed a reduction of ciliary length associated with all the studied variants, thus confirming a deleterious effect. Taken together, our results seem to prove the pathogenicity of the already classified and unclassified new BBS variants, as well as highlight the usefulness of zebrafish as an animal model for in vivo assays in human ciliopathies.
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24
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Haq N, Schmidt-Hieber C, Sialana FJ, Ciani L, Heller JP, Stewart M, Bentley L, Wells S, Rodenburg RJ, Nolan PM, Forsythe E, Wu MC, Lubec G, Salinas P, Häusser M, Beales PL, Christou-Savina S. Loss of Bardet-Biedl syndrome proteins causes synaptic aberrations in principal neurons. PLoS Biol 2019; 17:e3000414. [PMID: 31479441 PMCID: PMC6743795 DOI: 10.1371/journal.pbio.3000414] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 09/13/2019] [Accepted: 08/19/2019] [Indexed: 02/07/2023] Open
Abstract
Bardet-Biedl syndrome (BBS), a ciliopathy, is a rare genetic condition characterised by retinal degeneration, obesity, kidney failure, and cognitive impairment. In spite of progress made in our general understanding of BBS aetiology, the molecular and cellular mechanisms underlying cognitive impairment in BBS remain elusive. Here, we report that the loss of BBS proteins causes synaptic dysfunction in principal neurons, providing a possible explanation for the cognitive impairment phenotype observed in BBS patients. Using synaptosomal proteomics and immunocytochemistry, we demonstrate the presence of Bbs proteins in the postsynaptic density (PSD) of hippocampal neurons. Loss of Bbs results in a significant reduction of dendritic spines in principal neurons of Bbs mouse models. Furthermore, we show that spine deficiency correlates with events that destabilise spine architecture, such as impaired spine membrane receptor signalling, known to be involved in the maintenance of dendritic spines. Our findings suggest a role for BBS proteins in dendritic spine homeostasis that may be linked to the cognitive phenotype observed in BBS.
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Affiliation(s)
- Naila Haq
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Christoph Schmidt-Hieber
- Wolfson Institute for Biomedical Research and Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Fernando J. Sialana
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Lorenza Ciani
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Janosch P. Heller
- Institute of Neurology, University College London, London, United Kingdom
| | - Michelle Stewart
- MRC Harwell Institute, Mary Lyon Centre, Harwell Campus, Oxfordshire, United Kingdom
| | - Liz Bentley
- MRC Harwell Institute, Mary Lyon Centre, Harwell Campus, Oxfordshire, United Kingdom
| | - Sara Wells
- MRC Harwell Institute, Mary Lyon Centre, Harwell Campus, Oxfordshire, United Kingdom
| | - Richard J. Rodenburg
- Radboud Center for Mitochondrial Medicine, Translational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Patrick M. Nolan
- MRC Harwell Institute, Mary Lyon Centre, Harwell Campus, Oxfordshire, United Kingdom
| | - Elizabeth Forsythe
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Michael C. Wu
- Neurodigitech, LLC, San Diego, California, United States of America
| | - Gert Lubec
- Programme in Proteomics, Paracelsus Private Medical University, Salzburg, Austria
| | - P. Salinas
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Michael Häusser
- Wolfson Institute for Biomedical Research and Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Philip L. Beales
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Sofia Christou-Savina
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
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Chu Q, Yao C, Qi X, Stripp BR, Tang N. STK11 is required for the normal program of ciliated cell differentiation in airways. Cell Discov 2019; 5:36. [PMID: 31636950 PMCID: PMC6796922 DOI: 10.1038/s41421-019-0104-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/06/2019] [Accepted: 05/31/2019] [Indexed: 01/07/2023] Open
Abstract
The functional properties of mucosal surfaces are dependent on establishing the correct proportions of specialized epithelial cell types. Multiciliated cells (also known as ciliated cells) are evolutionarily conserved and functionally indispensable epithelial cells, as suggested by the link between ciliated cell dysfunction and chronic human disease. Ciliated cell differentiation is an ordered process that involves initial cell fate determination and multiciliogenesis. STK11, a serine/threonine kinase, has been reported to be downregulated in human diseases associated with ciliopathies and functions as a tumor suppressor. Here, we show that STK11 is a physiological factor for the normal program of ciliated cell differentiation by phosphorylating MARK3, which directly suppresses ERK1/2 mediated pRB inactivation. Loss of Stk11 in airway progenitors impairs the differentiation of ciliated cells in both embryonic and adult airways. Our study establishes that STK11/MARK3/ERK1/2 signaling cascade is a key regulator to integrate ciliated cell fate commitment and the subsequent process of multiciliogenesis.
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Affiliation(s)
- Qiqi Chu
- College of Life Sciences, Beijing Normal University, 100875 Beijing, China
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Changfu Yao
- Lung and Board of Governors Regenerative Medicine Institutes, Department of Medicine, Cedars-Sinai Medical Center, 90048 Los Angeles, CA USA
| | - Xiangbing Qi
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Barry Raymond Stripp
- Lung and Board of Governors Regenerative Medicine Institutes, Department of Medicine, Cedars-Sinai Medical Center, 90048 Los Angeles, CA USA
| | - Nan Tang
- National Institute of Biological Sciences, 102206 Beijing, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, 100084 Beijing, China
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Anosov M, Birk R. Bardet-Biedl syndrome obesity: BBS4 regulates cellular ER stress in early adipogenesis. Mol Genet Metab 2019; 126:495-503. [PMID: 30902542 DOI: 10.1016/j.ymgme.2019.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/16/2019] [Accepted: 03/14/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Bardet-Biedl syndrome (BBS) is an autosomal recessive ciliopathy, presenting with early obesity onset. The etiology of BBS obesity involves both central and peripheral defects, through mechanisms mostly yet to be deciphered. We previously showed BBS4 expression in adipogenesis, peaking at day 3 of differentiation. Obesity is characterized by cellular stress which promotes pathological consequences. AIMS We set out to test a possible role of BBS4 in adipocyte endoplasmic reticulum (ER) stress-induced unfolding protein response (UPR). METHODS BBS4 silenced (SiBBS4) and overexpressing (OEBBS4) pre-adipocyte murine cell lines were subjected to ER-stress induction (Tunicamycin, TM) during adipogenesis. ER-stress UPR was analyzed at the transcript, protein and biochemical levels (microscopy, immunocytochemistry, western blotting, quantitative RT-PCR and X-box binding protein 1 (XBP-1) splicing). RESULTS In silico analysis showed that BBS4 harbors an ER localization sequences indicative of ER localization. We verified BBS4's ER localization in adipocytes by immunocytochemistry and cellular protein fractionation. Furthermore, we demonstrated that BBS4 expression is significantly up-regulated by ER-stress, as indicated by protein and transcript levels. SiBBS4 adipocytes exhibited swollen ER typical to ER-stress and significant XBP-1 down-regulation at day 3 of differentiation. Following ER-stress, SiBBS4 adipocytes exhibited XBP-1 ER retention, failure to translocate to the nucleus and depletion of the nuclear active cleaved ATF6α. BBS4 did not alter ATF6α processing by S1P and S2P in the Golgi. Notably, SiBBS4 cells demonstrated significant reduction in the downstream activated phospho-IRE1α, independent of ER-stress. CONCLUSIONS At day 3 of adipogenesis, coinciding with the timing of its peak expression, BBS4 is localized to the ER and is involved in the ER stress response and trafficking. BBS4 depletion results in swollen ER with impaired intracellular nucleus translocation of XBP-1 and ATF6α. Thus, BBS4 affects the ER stress response in early adipogenesis, altering ER stress responsiveness and the adipocyte ER phenotype.
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Affiliation(s)
- Mariana Anosov
- Department of Nutrition, Faculty of Health Sciences, Ariel University, 40700, Israel
| | - Ruth Birk
- Department of Nutrition, Faculty of Health Sciences, Ariel University, 40700, Israel.
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Uytingco CR, Williams CL, Xie C, Shively DT, Green WW, Ukhanov K, Zhang L, Nishimura DY, Sheffield VC, Martens JR. BBS4 is required for intraflagellar transport coordination and basal body number in mammalian olfactory cilia. J Cell Sci 2019; 132:jcs222331. [PMID: 30665891 PMCID: PMC6432715 DOI: 10.1242/jcs.222331] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 01/11/2019] [Indexed: 12/16/2022] Open
Abstract
Bardet-Beidl syndrome (BBS) manifests from genetic mutations encoding for one or more BBS proteins. BBS4 loss impacts olfactory ciliation and odor detection, yet the cellular mechanisms remain unclear. Here, we report that Bbs4-/- mice exhibit shorter and fewer olfactory sensory neuron (OSN) cilia despite retaining odorant receptor localization. Within Bbs4-/- OSN cilia, we observed asynchronous rates of IFT-A/B particle movements, indicating miscoordination in IFT complex trafficking. Within the OSN dendritic knob, the basal bodies are dynamic, with incorporation of ectopically expressed centrin-2 and γ-tubulin occurring after nascent ciliogenesis. Importantly, BBS4 loss results in the reduction of basal body numbers separate from cilia loss. Adenoviral expression of BBS4 restored OSN cilia lengths and was sufficient to re-establish odor detection, but failed to rescue ciliary and basal body numbers. Our results yield a model for the plurality of BBS4 functions in OSNs that includes intraciliary and periciliary roles that can explain the loss of cilia and penetrance of ciliopathy phenotypes in olfactory neurons.
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Affiliation(s)
- Cedric R Uytingco
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Corey L Williams
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Chao Xie
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Dana T Shively
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Warren W Green
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Kirill Ukhanov
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Lian Zhang
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | | | - Val C Sheffield
- Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
- Howard Hughes Medical Institute, University of Iowa, Iowa City, IA 52242, USA
| | - Jeffrey R Martens
- Department of Pharmacology and Therapeutics, Gainesville, FL 32610, USA
- Center for Smell and Taste, University of Florida College of Medicine, Gainesville, FL 32610, USA
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The complexity of the cilium: spatiotemporal diversity of an ancient organelle. Curr Opin Cell Biol 2018; 55:139-149. [PMID: 30138887 DOI: 10.1016/j.ceb.2018.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 07/31/2018] [Accepted: 08/02/2018] [Indexed: 02/06/2023]
Abstract
Cilia are microtubule-based appendages present on almost all vertebrate cell types where they mediate a myriad of cellular processes critical for development and homeostasis. In humans, impaired ciliary function is associated with an ever-expanding repertoire of phenotypically-overlapping yet highly variable genetic disorders, the ciliopathies. Extensive work to elucidate the structure, function, and composition of the cilium is offering hints that the `static' representation of the cilium is a gross oversimplification of a highly dynamic organelle whose functions are choreographed dynamically across cell types, developmental, and homeostatic contexts. Understanding this diversity will require discerning ciliary versus non-ciliary roles for classically-defined `ciliary' proteins; defining ciliary protein-protein interaction networks within and beyond the cilium; and resolving the spatiotemporal diversity of ciliary structure and function. Here, focusing on one evolutionarily conserved ciliary module, the intraflagellar transport system, we explore these ideas and propose potential future studies that will improve our knowledge gaps of the oversimplified cilium and, by extension, inform the reasons that underscore the striking range of clinical pathologies associated with ciliary dysfunction.
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Kinesin 1 regulates cilia length through an interaction with the Bardet-Biedl syndrome related protein CCDC28B. Sci Rep 2018; 8:3019. [PMID: 29445114 PMCID: PMC5813027 DOI: 10.1038/s41598-018-21329-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 02/02/2018] [Indexed: 01/12/2023] Open
Abstract
Bardet-Biedl syndrome (BBS) is a ciliopathy characterized by retinal degeneration, obesity, polydactyly, renal disease and mental retardation. CCDC28B is a BBS-associated protein that we have previously shown plays a role in cilia length regulation whereby its depletion results in shortened cilia both in cells and Danio rerio (zebrafish). At least part of that role is achieved by its interaction with the mTORC2 component SIN1, but the mechanistic details of this interaction and/or additional functions that CCDC28B might play in the context of cilia remain poorly understood. Here we uncover a novel interaction between CCDC28B and the kinesin 1 molecular motor that is relevant to cilia. CCDC28B interacts with kinesin light chain 1 (KLC1) and the heavy chain KIF5B. Notably, depletion of these kinesin 1 components results in abnormally elongated cilia. Furthermore, through genetic interaction studies we demonstrate that kinesin 1 regulates ciliogenesis through CCDC28B. We show that kinesin 1 regulates the subcellular distribution of CCDC28B, unexpectedly, inhibiting its nuclear accumulation, and a ccdc28b mutant missing a nuclear localization motif fails to rescue the phenotype in zebrafish morphant embryos. Therefore, we uncover a previously unknown role of kinesin 1 in cilia length regulation that relies on the BBS related protein CCDC28B.
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McClure-Begley TD, Klymkowsky MW. Nuclear roles for cilia-associated proteins. Cilia 2017; 6:8. [PMID: 28560031 PMCID: PMC5445336 DOI: 10.1186/s13630-017-0052-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 05/02/2017] [Indexed: 01/23/2023] Open
Abstract
Cilia appear to be derived, evolutionarily, from structures present in the ancestral (pre-ciliary) eukaryote, such as microtubule-based vesicle trafficking and chromosome segregation systems. Experimental observations suggest that the ciliary gate, the molecular complex that mediates the selective molecular movement between cytoplasmic and ciliary compartments, shares features with nuclear pores. Our hypothesis is that this shared transport machinery is at least partially responsible for the observation that a number of ciliary and ciliogenesis-associated proteins are found within nuclei where they play roles in the regulation of gene expression, DNA repair, and nuclear import and export. Recognizing the potential for such nuclear roles is critical when considering the phenotypic effects that arise from the mutational modification of ciliary proteins.
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Affiliation(s)
- Tristan D McClure-Begley
- Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309 USA
| | - Michael W Klymkowsky
- Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309 USA
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31
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Control of Hedgehog Signalling by the Cilia-Regulated Proteasome. J Dev Biol 2016; 4:jdb4030027. [PMID: 29615591 PMCID: PMC5831775 DOI: 10.3390/jdb4030027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/25/2016] [Accepted: 08/29/2016] [Indexed: 12/31/2022] Open
Abstract
The Hedgehog signalling pathway is evolutionarily highly conserved and essential for embryonic development of invertebrates and vertebrates. Consequently, impaired Hedgehog signalling results in very severe human diseases, ranging from holoprosencephaly to Pallister-Hall syndrome. Due to this great importance for human health, the focus of numerous research groups is placed on the investigation of the detailed mechanisms underlying Hedgehog signalling. Today, it is known that tiny cell protrusions, known as primary cilia, are necessary to mediate Hedgehog signalling in vertebrates. Although the Hedgehog pathway is one of the best studied signalling pathways, many questions remain. One of these questions is: How do primary cilia control Hedgehog signalling in vertebrates? Recently, it was shown that primary cilia regulate a special kind of proteasome which is essential for proper Hedgehog signalling. This review article will cover this novel cilia-proteasome association in embryonic Hedgehog signalling and discuss the possibilities provided by future investigations on this topic.
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Torrado B, Graña M, Badano JL, Irigoín F. Ciliary Entry of the Hedgehog Transcriptional Activator Gli2 Is Mediated by the Nuclear Import Machinery but Differs from Nuclear Transport in Being Imp-α/β1-Independent. PLoS One 2016; 11:e0162033. [PMID: 27579771 PMCID: PMC5007031 DOI: 10.1371/journal.pone.0162033] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 08/16/2016] [Indexed: 01/20/2023] Open
Abstract
Gli2 is the primary transcriptional activator of Hedgehog signalling in mammals. Upon stimulation of the pathway, Gli2 moves into the cilium before reaching the nucleus. However, the mechanisms underlying its entry into the cilium are not completely understood. Since several similarities have been reported between nuclear and ciliary import, we investigated if the nuclear import machinery participates in Gli2 ciliary entry. Here we show that while two conserved classical nuclear localization signals mediate Gli2 nuclear localization via importin (Imp)-α/β1, these sequences are not required for Gli2 ciliary import. However, blocking Imp-mediated transport through overexpression of GTP-locked Ran reduced the percentage of Gli2 positive cilia, an effect that was not explained by increased CRM1-dependent export of Gli2 from the cilium. We explored the participation of Imp-β2 in Gli2 ciliary traffic and observed that this transporter is involved in moving Gli2 into the cilium, as has been described for other ciliary proteins. In addition, our data indicate that Imp-β2 might also collaborate in Gli2 nuclear entry. How does Imp-β2 determine the final destination of a protein that can localize to two distinct subcellular compartments remains an open question. Therefore, our data shows that the nuclear-cytoplasmic shuttling machinery plays a critical role mediating the subcellular distribution of Gli2 and the activation of the pathway, but distinct importins likely play a differential role mediating its ciliary and nuclear translocation.
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Affiliation(s)
- Belén Torrado
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
| | - Martín Graña
- Bioinformatics Unit, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
| | - José L. Badano
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
| | - Florencia Irigoín
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Gral. Flores 2125, Montevideo CP11800, Uruguay
- * E-mail:
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Gerhardt C, Leu T, Lier JM, Rüther U. The cilia-regulated proteasome and its role in the development of ciliopathies and cancer. Cilia 2016; 5:14. [PMID: 27293550 PMCID: PMC4901515 DOI: 10.1186/s13630-016-0035-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 02/29/2016] [Indexed: 12/21/2022] Open
Abstract
The primary cilium is an essential structure for the mediation of numerous signaling pathways involved in the coordination and regulation of cellular processes essential for the development and maintenance of health. Consequently, ciliary dysfunction results in severe human diseases called ciliopathies. Since many of the cilia-mediated signaling pathways are oncogenic pathways, cilia are linked to cancer. Recent studies demonstrate the existence of a cilia-regulated proteasome and that this proteasome is involved in cancer development via the progression of oncogenic, cilia-mediated signaling. This review article investigates the association between primary cilia and cancer with particular emphasis on the role of the cilia-regulated proteasome.
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Affiliation(s)
- Christoph Gerhardt
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Tristan Leu
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Johanna Maria Lier
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Ulrich Rüther
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
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Hostelley TL, Lodh S, Zaghloul NA. Whole organism transcriptome analysis of zebrafish models of Bardet-Biedl Syndrome and Alström Syndrome provides mechanistic insight into shared and divergent phenotypes. BMC Genomics 2016; 17:318. [PMID: 27142762 PMCID: PMC4855444 DOI: 10.1186/s12864-016-2679-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/28/2016] [Indexed: 12/14/2022] Open
Abstract
Background Bardet-Biedl Syndrome (BBS) and Alström Syndrome are two pleiotropic ciliopathies with significant phenotypic overlap between them across many tissues. Although BBS and Alström genes are necessary for the proper function of primary cilia, their role in defects across multiple organ systems is unclear. Methods To provide insight into the pathways underlying BBS and Alström phenotypes, we carried out whole organism transcriptome analysis by RNA sequencing in established zebrafish models of the syndromes. Results We analyzed all genes that were significantly differentially expressed and found enrichment of phenotypically significant pathways in both models. These included multiple pathways shared between the two disease models as well as those unique to each model. Notably, we identified significant downregulation of genes in pathways relevant to visual system deficits and obesity in both disorders, consistent with those shared phenotypes. In contrast, neuronal pathways were significantly downregulated only in the BBS model but not in the Alström model. Our observations also suggested an important role for G-protein couple receptor and calcium signaling defects in both models. Discussion Pathway network analyses of both models indicate that visual system defects may be driven by genetic mechanisms independent of other phenotypes whereas the majority of other phenotypes are a result of genetic players that contribute to multiple pathways simultaneously. Additionally, examination of genes differentially expressed in opposing directions between the two models suggest a deficit in pancreatic function in the Alström model, that is not present in the BBS model. Conclusions These findings provide important novel insight into shared and divergent phenotypes between two similar but distinct genetic syndromes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2679-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Timothy L Hostelley
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 660 W. Redwood Street, Howard Hall 487, Baltimore, MD, 21201, USA
| | - Sukanya Lodh
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 660 W. Redwood Street, Howard Hall 487, Baltimore, MD, 21201, USA
| | - Norann A Zaghloul
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 660 W. Redwood Street, Howard Hall 487, Baltimore, MD, 21201, USA.
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Gerhardt C, Lier JM, Burmühl S, Struchtrup A, Deutschmann K, Vetter M, Leu T, Reeg S, Grune T, Rüther U. The transition zone protein Rpgrip1l regulates proteasomal activity at the primary cilium. J Cell Biol 2015; 210:115-33. [PMID: 26150391 PMCID: PMC4494006 DOI: 10.1083/jcb.201408060] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Rpgrip1l regulates proteasomal activity at the basal body via Psmd2 and thereby controls ciliary signaling. Mutations in RPGRIP1L result in severe human diseases called ciliopathies. To unravel the molecular function of RPGRIP1L, we analyzed Rpgrip1l−/− mouse embryos, which display a ciliopathy phenotype and die, at the latest, around birth. In these embryos, cilia-mediated signaling was severely disturbed. Defects in Shh signaling suggested that the Rpgrip1l deficiency causes an impairment of protein degradation and protein processing. Indeed, we detected a cilia-dependent decreased proteasomal activity in the absence of Rpgrip1l. We found different proteasomal components localized to cilia and identified Psmd2, a component of the regulatory proteasomal 19S subunit, as an interaction partner for Rpgrip1l. Quantifications of proteasomal substrates demonstrated that Rpgrip1l regulates proteasomal activity specifically at the basal body. Our study suggests that Rpgrip1l controls ciliary signaling by regulating the activity of the ciliary proteasome via Psmd2.
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Affiliation(s)
- Christoph Gerhardt
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Johanna Maria Lier
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Stephan Burmühl
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Andreas Struchtrup
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Kathleen Deutschmann
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Maik Vetter
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Tristan Leu
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Sandra Reeg
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller University Jena, 07743 Jena, Germany
| | - Tilman Grune
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller University Jena, 07743 Jena, Germany
| | - Ulrich Rüther
- Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
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Novas R, Cardenas-Rodriguez M, Irigoín F, Badano JL. Bardet-Biedl syndrome: Is it only cilia dysfunction? FEBS Lett 2015; 589:3479-91. [PMID: 26231314 DOI: 10.1016/j.febslet.2015.07.031] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 07/14/2015] [Accepted: 07/15/2015] [Indexed: 01/12/2023]
Abstract
Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, pleiotropic disorder, characterized by both congenital and late onset defects. From the analysis of the mutational burden in patients to the functional characterization of the BBS proteins, this syndrome has become a model for both understanding oligogenic patterns of inheritance and the biology of a particular cellular organelle: the primary cilium. Here we briefly review the genetics of BBS to then focus on the function of the BBS proteins, not only in the context of the cilium but also highlighting potential extra-ciliary roles that could be relevant to the etiology of the disorder. Finally, we provide an overview of how the study of this rare syndrome has contributed to the understanding of cilia biology and how this knowledge has informed on the cellular basis of different clinical manifestations that characterize BBS and the ciliopathies.
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Affiliation(s)
- Rossina Novas
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay
| | | | - Florencia Irigoín
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay; Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Gral. Flores 2125, Montevideo CP11800, Uruguay
| | - Jose L Badano
- Human Molecular Genetics Laboratory, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP11400, Uruguay.
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Braunreiter K, Hamlin S, Lyman-Gingerich J. Identification and characterization of a novel allele of Caenorhabditis elegans bbs-7. PLoS One 2014; 9:e113737. [PMID: 25486278 PMCID: PMC4259304 DOI: 10.1371/journal.pone.0113737] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 10/29/2014] [Indexed: 01/25/2023] Open
Abstract
Primary cilia play a role in the sensation of and response to the surrounding environment. Caenorhabditis elegans (C. elegans) have primary cilia only on the distal tips of some dendrites. In order to better understand the relationship between receptor localization to cilia, cilia structure and cilia function, we have characterized a mutation originally identified in a forward genetic screen for mutants with defective PKD-2 ciliary localization. Through behavioral assays and examination of the structure of cilia in the cil-5 (my13) mutant animals, we have found that my13 disrupts not only receptor localization, but also some cilia-mediated sensory behaviors and cilia structural integrity. We have identified the my13 lesion and found that it is a missense mutation in bbs-7, an ortholog of human BBS-7, a gene known to affect human cilia and to be involved in Bardet-Biedl syndrome. Finally, we show that bbs-7(my13) also affects the glia cells which support the cilia.
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Affiliation(s)
- Kara Braunreiter
- Department of Biology, University of Wisconsin-Eau Claire, Phillips Hall 330, Eau Claire, Wisconsin, United States of America
| | - Shelby Hamlin
- Department of Biology, University of Wisconsin-Eau Claire, Phillips Hall 330, Eau Claire, Wisconsin, United States of America
| | - Jamie Lyman-Gingerich
- Department of Biology, University of Wisconsin-Eau Claire, Phillips Hall 330, Eau Claire, Wisconsin, United States of America
- * E-mail:
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Vogel TW, Carter CS, Abode-Iyamah K, Zhang Q, Robinson S. The role of primary cilia in the pathophysiology of neural tube defects. Neurosurg Focus 2013; 33:E2. [PMID: 23025443 DOI: 10.3171/2012.6.focus12222] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Neural tube defects (NTDs) are a set of disorders that occur from perturbation of normal neural development. They occur in open or closed forms anywhere along the craniospinal axis and often result from a complex interaction between environmental and genetic factors. One burgeoning area of genetics research is the effect of cilia signaling on the developing neural tube and how the disruption of primary cilia leads to the development of NTDs. Recent progress has implicated the hedgehog (Hh), wingless-type integration site family (Wnt), and planar cell polarity (PCP) pathways in primary cilia as involved in normal neural tube patterning. A set of disorders involving cilia function, known as ciliopathies, offers insight into abnormal neural development. In this article, the authors discuss the common ciliopathies, such as Meckel-Gruber and Joubert syndromes, that are associated with NTDs, and review cilia-related signaling cascades responsible for mammalian neural tube development. Understanding the contribution of cilia in the formation of NTDs may provide greater insight into this common set of pediatric neurological disorders.
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Affiliation(s)
- Timothy W Vogel
- Department of Neurosurgery, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
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Cardenas-Rodriguez M, Osborn DPS, Irigoín F, Graña M, Romero H, Beales PL, Badano JL. Characterization of CCDC28B reveals its role in ciliogenesis and provides insight to understand its modifier effect on Bardet-Biedl syndrome. Hum Genet 2012; 132:91-105. [PMID: 23015189 DOI: 10.1007/s00439-012-1228-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 09/15/2012] [Indexed: 11/26/2022]
Abstract
Bardet-Biedl syndrome (BBS) is a genetically heterogeneous disorder that is generally inherited in an autosomal recessive fashion. However, in some families, trans mutant alleles interact with the primary causal locus to modulate the penetrance and/or the expressivity of the phenotype. CCDC28B (MGC1203) was identified as a second site modifier of BBS encoding a protein of unknown function. Here we report the first functional characterization of this protein and show it affects ciliogenesis both in cultured cells and in vivo in zebrafish. Consistent with this biological role, our in silico analysis shows that the presence of CCDC28B homologous sequences is restricted to ciliated metazoa. Depletion of Ccdc28b in zebrafish results in defective ciliogenesis and consequently causes a number of phenotypes that are characteristic of BBS and other ciliopathy mutants including hydrocephalus, left-right axis determination defects and renal function impairment. Thus, this work reports CCDC28B as a novel protein involved in the process of ciliogenesis whilst providing functional insight into the cellular basis of its modifier effect in BBS patients.
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Price HP, Hodgkinson MR, Wright MH, Tate EW, Smith BA, Carrington M, Stark M, Smith DF. A role for the vesicle-associated tubulin binding protein ARL6 (BBS3) in flagellum extension in Trypanosoma brucei. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1823:1178-91. [PMID: 22609302 PMCID: PMC3793860 DOI: 10.1016/j.bbamcr.2012.05.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 04/23/2012] [Accepted: 05/05/2012] [Indexed: 11/17/2022]
Abstract
The small GTPase Arl6 is implicated in the ciliopathic human genetic disorder Bardet-Biedl syndrome, acting at primary cilia in recruitment of the octomeric BBSome complex, which is required for specific trafficking events to and from the cilium in eukaryotes. Here we describe functional characterisation of Arl6 in the flagellated model eukaryote Trypanosoma brucei, which requires motility for viability. Unlike human Arl6 which has a ciliary localisation, TbARL6 is associated with electron-dense vesicles throughout the cell body following co-translational modification by N-myristoylation. Similar to the related protein ARL-3A in T. brucei, modulation of expression of ARL6 by RNA interference does not prevent motility but causes a significant reduction in flagellum length. Tubulin is identified as an ARL6 interacting partner, suggesting that ARL6 may act as an anchor between vesicles and cytoplasmic microtubules. We provide evidence that the interaction between ARL6 and the BBSome is conserved in unicellular eukaryotes. Overexpression of BBS1 leads to translocation of endogenous ARL6 to the site of exogenous BBS1 at the flagellar pocket. Furthermore, a combination of BBS1 overexpression and ARL6 RNAi has a synergistic inhibitory effect on cell growth. Our findings indicate that ARL6 in trypanosomes contributes to flagellum biogenesis, most likely through an interaction with the BBSome.
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Key Words
- arf, adp-ribosylation factor
- arl, adp-ribosylation factor-like
- arl6ip, arl6 interacting protein
- bbs, bardet–biedl syndrome
- bbs1, bardet–biedl syndrome 1 protein
- bsf, bloodstream form
- cona, concanavalin a
- gef, guanine nucleotide exchange factor
- gpcr, g-protein coupled receptor
- hrg4, human retinal gene 4
- ift, intraflagellar transport
- itc, isothermal titration calorimetry
- mant, n-methylanthraniloyl
- map2, microtubule associated protein 2
- nes, nuclear export signal
- nls, nuclear localisation signal
- nmt, myristoyl-coa:protein n-myristoyltransferase
- pcf, procyclic form
- pcm1, pericentriolar material 1
- pfr, paraflagellar rod
- pm, plasma membrane
- rnai, rna interference
- rp2, retinitis pigmentosa protein 2
- tap, tandem affinity purification
- tiem, transmission immuno-electron microscopy
- trypanosoma brucei
- arl6
- bbsome
- bbs1
- flagellum
- tubulin
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Affiliation(s)
- Helen P Price
- Centre for Immunology and Infection, Department of Biology, University of York, Heslington, York YO10 5YW, UK.
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Davis EE, Katsanis N. The ciliopathies: a transitional model into systems biology of human genetic disease. Curr Opin Genet Dev 2012; 22:290-303. [PMID: 22632799 DOI: 10.1016/j.gde.2012.04.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 04/24/2012] [Accepted: 04/24/2012] [Indexed: 01/19/2023]
Abstract
The last decade has witnessed an explosion in the identification of genes, mutations in which appear sufficient to cause clinical phenotypes in humans. This is especially true for disorders of ciliary dysfunction in which an excess of 50 causal loci are now known; this discovery was driven partly by an improved understanding of the protein composition of the cilium and the co-occurrence of clinical phenotypes associated with ciliary dysfunction. Despite this progress, the fundamental challenge of predicting phenotype and or clinical progression based on single locus information remains unsolved. Here, we explore how the combinatorial knowledge of allele quality and quantity, an improved understanding of the biological composition of the primary cilium, and the expanded appreciation of the subcellular roles of this organelle can be synthesized to generate improved models that can explain both causality but also variable penetrance and expressivity.
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Affiliation(s)
- Erica E Davis
- Center for Human Disease Modeling, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
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