1
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Vuong LT, Mlodzik M. The complex relationship of Wnt-signaling pathways and cilia. Curr Top Dev Biol 2023; 155:95-125. [PMID: 38043953 DOI: 10.1016/bs.ctdb.2023.09.002] [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] [Indexed: 12/05/2023]
Abstract
Wnt family proteins are secreted glycolipoproteins that signal through multitude of signal transduction pathways. The Wnt-pathways are conserved and critical in all metazoans. They are essential for embryonic development, organogenesis and homeostasis, and associated with many diseases when defective or deregulated. Wnt signaling pathways comprise the canonical Wnt pathway, best known for its stabilization of β-catenin and associated nuclear β-catenin activity in gene regulation, and several non-canonical signaling branches. Wnt-Planar Cell Polarity (PCP) signaling has received the most attention among the non-canonical Wnt pathways. The relationship of cilia to Wnt-signaling is complex. While it was suggested that canonical Wnt signaling requires cilia this notion was always challenged by results suggesting the opposite. Recent developments provide insight and clarification to the relationship of Wnt signaling pathways and cilia. First, it has been now demonstrated that while ciliary proteins, in particular the IFT-A complex, are required for canonical Wnt/β-catenin signaling, the cilium as a structure is not. In contrast, recent work has defined a diverged canonical signaling branch (not affecting β-catenin) to be required for ciliary biogenesis and cilia function. Furthermore, the non-canonical Wnt-PCP pathway does not affect cilia biogenesis per se, but it regulates the position of cilia within cells in many cell types, possibly in all cells where it is active, with cilia being placed near the side of the cell that has the Frizzled-Dishevelled complex. This Wnt/PCP feature is conserved with both centrioles and basal bodies/cilia being positioned accordingly, and it is also used to align mitotic spindles within the Wnt-PCP polarization axis. It also coordinates the alignment of cilia in multiciliated cells. This article addresses these new insights and different links and relationships between cilia and Wnt signaling.
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Affiliation(s)
- Linh T Vuong
- Department of Cell, Developmental, & Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Marek Mlodzik
- Department of Cell, Developmental, & Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
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2
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Saito M, Otsu W, Miyadera K, Nishimura Y. Recent advances in the understanding of cilia mechanisms and their applications as therapeutic targets. Front Mol Biosci 2023; 10:1232188. [PMID: 37780208 PMCID: PMC10538646 DOI: 10.3389/fmolb.2023.1232188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/24/2023] [Indexed: 10/03/2023] Open
Abstract
The primary cilium is a single immotile microtubule-based organelle that protrudes into the extracellular space. Malformations and dysfunctions of the cilia have been associated with various forms of syndromic and non-syndromic diseases, termed ciliopathies. The primary cilium is therefore gaining attention due to its potential as a therapeutic target. In this review, we examine ciliary receptors, ciliogenesis, and ciliary trafficking as possible therapeutic targets. We first discuss the mechanisms of selective distribution, signal transduction, and physiological roles of ciliary receptors. Next, pathways that regulate ciliogenesis, specifically the Aurora A kinase, mammalian target of rapamycin, and ubiquitin-proteasome pathways are examined as therapeutic targets to regulate ciliogenesis. Then, in the photoreceptors, the mechanism of ciliary trafficking which takes place at the transition zone involving the ciliary membrane proteins is reviewed. Finally, some of the current therapeutic advancements highlighting the role of large animal models of photoreceptor ciliopathy are discussed.
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Affiliation(s)
- Masaki Saito
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
| | - Wataru Otsu
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan
| | - Keiko Miyadera
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Yuhei Nishimura
- Department of Integrative Pharmacology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
- Mie University Research Center for Cilia and Diseases, Tsu, Mie, Japan
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3
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Li FL, Guan KL. The Arf family GTPases: Regulation of vesicle biogenesis and beyond. Bioessays 2023; 45:e2200214. [PMID: 36998106 PMCID: PMC10282109 DOI: 10.1002/bies.202200214] [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: 11/05/2022] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 04/01/2023]
Abstract
The Arf family proteins are best known for their roles in the vesicle biogenesis. However, they also play fundamental roles in a wide range of cellular regulation besides vesicular trafficking, such as modulation of lipid metabolic enzymes, cytoskeleton remodeling, ciliogenesis, lysosomal, and mitochondrial morphology and functions. Growing studies continue to expand the downstream effector landscape of Arf proteins, especially for the less-studied members, revealing new biological functions, such as amino acid sensing. Experiments with cutting-edge technologies and in vivo functional studies in the last decade help to provide a more comprehensive view of Arf family functions. In this review, we summarize the cellular functions that are regulated by at least two different Arf members with an emphasis on those beyond vesicle biogenesis.
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Affiliation(s)
- Fu-Long Li
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California San Diego, La Jolla, CA, USA
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4
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Yin G, Huang J, Petela J, Jiang H, Zhang Y, Gong S, Wu J, Liu B, Shi J, Gao Y. Targeting small GTPases: emerging grasps on previously untamable targets, pioneered by KRAS. Signal Transduct Target Ther 2023; 8:212. [PMID: 37221195 DOI: 10.1038/s41392-023-01441-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/28/2023] [Accepted: 04/14/2023] [Indexed: 05/25/2023] Open
Abstract
Small GTPases including Ras, Rho, Rab, Arf, and Ran are omnipresent molecular switches in regulating key cellular functions. Their dysregulation is a therapeutic target for tumors, neurodegeneration, cardiomyopathies, and infection. However, small GTPases have been historically recognized as "undruggable". Targeting KRAS, one of the most frequently mutated oncogenes, has only come into reality in the last decade due to the development of breakthrough strategies such as fragment-based screening, covalent ligands, macromolecule inhibitors, and PROTACs. Two KRASG12C covalent inhibitors have obtained accelerated approval for treating KRASG12C mutant lung cancer, and allele-specific hotspot mutations on G12D/S/R have been demonstrated as viable targets. New methods of targeting KRAS are quickly evolving, including transcription, immunogenic neoepitopes, and combinatory targeting with immunotherapy. Nevertheless, the vast majority of small GTPases and hotspot mutations remain elusive, and clinical resistance to G12C inhibitors poses new challenges. In this article, we summarize diversified biological functions, shared structural properties, and complex regulatory mechanisms of small GTPases and their relationships with human diseases. Furthermore, we review the status of drug discovery for targeting small GTPases and the most recent strategic progress focused on targeting KRAS. The discovery of new regulatory mechanisms and development of targeting approaches will together promote drug discovery for small GTPases.
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Affiliation(s)
- Guowei Yin
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, 518107, China.
| | - Jing Huang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
| | - Johnny Petela
- Wake Forest University School of Medicine, Winston-Salem, NC, 27101, USA
| | - Hongmei Jiang
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, 518107, China
| | - Yuetong Zhang
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
| | - Siqi Gong
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, 518107, China
- School of Medicine, Sun Yat-Sen University, Shenzhen, 518107, China
| | - Jiaxin Wu
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
| | - Bei Liu
- National Biomedical Imaging Center, School of Future Technology, Peking University, Beijing, 100871, China
| | - Jianyou Shi
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology, Chengdu, 610072, China.
| | - Yijun Gao
- State Key Laboratory of Oncology in South China, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China.
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5
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Zhang K, Da Silva F, Seidl C, Wilsch-Bräuninger M, Herbst J, Huttner WB, Niehrs C. Primary cilia are WNT-transducing organelles whose biogenesis is controlled by a WNT-PP1 axis. Dev Cell 2023; 58:139-154.e8. [PMID: 36693320 DOI: 10.1016/j.devcel.2022.12.006] [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: 03/21/2022] [Revised: 10/18/2022] [Accepted: 12/19/2022] [Indexed: 01/24/2023]
Abstract
WNT signaling is important in development, stem cell maintenance, and disease. WNT ligands typically signal via receptor activation across the plasma membrane to induce β-catenin-dependent gene activation. Here, we show that in mammalian primary cilia, WNT receptors relay a WNT/GSK3 signal that β-catenin-independently promotes ciliogenesis. Characterization of a LRP6 ciliary targeting sequence and monitoring of acute WNT co-receptor activation (phospho-LRP6) support this conclusion. Ciliary WNT signaling inhibits protein phosphatase 1 (PP1) activity, a negative regulator of ciliogenesis, by preventing GSK3-mediated phosphorylation of the PP1 regulatory inhibitor subunit PPP1R2. Concordantly, deficiency of WNT/GSK3 signaling by depletion of cyclin Y and cyclin-Y-like protein 1 induces primary cilia defects in mouse embryonic neuronal precursors, kidney proximal tubules, and adult mice preadipocytes.
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Affiliation(s)
- Kaiqing Zhang
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Fabio Da Silva
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Carina Seidl
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Michaela Wilsch-Bräuninger
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraβe 108, 01307 Dresden, Germany
| | - Jessica Herbst
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Wieland B Huttner
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraβe 108, 01307 Dresden, Germany
| | - Christof Niehrs
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Institute of Molecular Biology (IMB), 55128 Mainz, Germany.
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6
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Liu YX, Sun WY, Xue B, Zhang RK, Li WJ, Xie X, Fan ZC. ARL3 mediates BBSome ciliary turnover by promoting its outward movement across the transition zone. J Cell Biol 2022; 221:213491. [PMID: 36129685 PMCID: PMC9499826 DOI: 10.1083/jcb.202111076] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/13/2022] [Accepted: 07/11/2022] [Indexed: 01/16/2023] Open
Abstract
Ciliary receptors and their certain downstream signaling components undergo intraflagellar transport (IFT) as BBSome cargoes to maintain their ciliary dynamics for sensing and transducing extracellular stimuli inside the cell. Cargo-laden BBSomes pass the transition zone (TZ) for ciliary retrieval, but how this passage is controlled remains elusive. Here, we show that phospholipase D (PLD)-laden BBSomes shed from retrograde IFT trains at the proximal ciliary region right above the TZ to act as Arf-like 3 (ARL3) GTPase-specific effectors in Chlamydomonas cilia. Under physiological condition, ARL3GDP binds to the membrane for diffusing into cilia. Following nucleotide exchange, ARL3GTP detaches from the ciliary membrane, binds to retrograde IFT train-shed and PLD-laden BBSomes at the proximal ciliary region right above the TZ, and recruits them to pass the TZ for ciliary retrieval likely via diffusion. ARL3 mediates the ciliary dynamics of certain signaling molecules through facilitating BBSome ciliary retrieval, providing a mechanistic understanding behind why ARL3-related Joubert syndrome shares overlapping phenotypes with Bardet-Biedl syndrome.
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Affiliation(s)
- Yan-Xia Liu
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Wei-Yue Sun
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Bin Xue
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Rui-Kai Zhang
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Wen-Juan Li
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Xixian Xie
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Zhen-Chuan Fan
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
- Correspondence to Zhen-Chuan Fan:
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7
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Specialization of the photoreceptor transcriptome by Srrm3-dependent microexons is required for outer segment maintenance and vision. Proc Natl Acad Sci U S A 2022; 119:e2117090119. [PMID: 35858306 PMCID: PMC9303857 DOI: 10.1073/pnas.2117090119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Retinal photoreceptors have a distinct transcriptomic profile compared to other neuronal subtypes, likely reflecting their unique cellular morphology and function in the detection of light stimuli by way of the ciliary outer segment. We discovered a layer of this molecular specialization by revealing that the vertebrate retina expresses the largest number of tissue-enriched microexons of all tissue types. A subset of these microexons is included exclusively in photoreceptor transcripts, particularly in genes involved in cilia biogenesis and vesicle-mediated transport. This microexon program is regulated by Srrm3, a paralog of the neural microexon regulator Srrm4. Despite the fact that both proteins positively regulate retina microexons in vitro, only Srrm3 is highly expressed in mature photoreceptors. Its deletion in zebrafish results in widespread down-regulation of microexon inclusion from early developmental stages, followed by other transcriptomic alterations, severe photoreceptor defects, and blindness. These results shed light on the transcriptomic specialization and functionality of photoreceptors, uncovering unique cell type-specific roles for Srrm3 and microexons with implications for retinal diseases.
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8
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Pablos M, Casanueva-Álvarez E, González-Casimiro CM, Merino B, Perdomo G, Cózar-Castellano I. Primary Cilia in Pancreatic β- and α-Cells: Time to Revisit the Role of Insulin-Degrading Enzyme. Front Endocrinol (Lausanne) 2022; 13:922825. [PMID: 35832432 PMCID: PMC9271624 DOI: 10.3389/fendo.2022.922825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 05/24/2022] [Indexed: 12/25/2022] Open
Abstract
The primary cilium is a narrow organelle located at the surface of the cell in contact with the extracellular environment. Once underappreciated, now is thought to efficiently sense external environmental cues and mediate cell-to-cell communication, because many receptors, ion channels, and signaling molecules are highly or differentially expressed in primary cilium. Rare genetic disorders that affect cilia integrity and function, such as Bardet-Biedl syndrome and Alström syndrome, have awoken interest in studying the biology of cilium. In this review, we discuss recent evidence suggesting emerging roles of primary cilium and cilia-mediated signaling pathways in the regulation of pancreatic β- and α-cell functions, and its implications in regulating glucose homeostasis.
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Affiliation(s)
- Marta Pablos
- Department of Biochemistry, Molecular Biology and Physiology, School of Medicine, University of Valladolid, Valladolid, Spain
- *Correspondence: Marta Pablos,
| | - Elena Casanueva-Álvarez
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Carlos M. González-Casimiro
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Beatriz Merino
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Germán Perdomo
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Irene Cózar-Castellano
- Department of Biochemistry, Molecular Biology and Physiology, School of Medicine, University of Valladolid, Valladolid, Spain
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
- Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
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9
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Development of a versatile HPLC-based method to evaluate the activation status of small GTPases. J Biol Chem 2021; 297:101428. [PMID: 34801548 PMCID: PMC8668980 DOI: 10.1016/j.jbc.2021.101428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/01/2021] [Accepted: 11/04/2021] [Indexed: 11/21/2022] Open
Abstract
Small GTPases cycle between an inactive GDP-bound and an active GTP-bound state to control various cellular events, such as cell proliferation, cytoskeleton organization, and membrane trafficking. Clarifying the guanine nucleotide-bound states of small GTPases is vital for understanding the regulation of small GTPase functions and the subsequent cellular responses. Although several methods have been developed to analyze small GTPase activities, our knowledge of the activities for many small GTPases is limited, partly because of the lack of versatile methods to estimate small GTPase activity without unique probes and specialized equipment. In the present study, we developed a versatile and straightforward HPLC-based assay to analyze the activation status of small GTPases by directly quantifying the amounts of guanine nucleotides bound to them. This assay was validated by analyzing the RAS-subfamily GTPases, including HRAS, which showed that the ratios of GTP-bound forms were comparable with those obtained in previous studies. Furthermore, we applied this assay to the investigation of psychiatric disorder-associated mutations of RHEB (RHEB/P37L and RHEB/S68P), revealing that both mutations cause an increase in the ratio of the GTP-bound form in cells. Mechanistically, loss of sensitivity to TSC2 (a GTPase-activating protein for RHEB) for RHEB/P37L, as well as both decreased sensitivity to TSC2 and accelerated guanine-nucleotide exchange for RHEB/S68P, is involved in the increase of their GTP-bound forms, respectively. In summary, the HPLC-based assay developed in this study provides a valuable tool for analyzing small GTPases for which the activities and regulatory mechanisms are less well understood.
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10
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Bardet-Biedl Syndrome-Multiple Kaleidoscope Images: Insight into Mechanisms of Genotype-Phenotype Correlations. Genes (Basel) 2021; 12:genes12091353. [PMID: 34573333 PMCID: PMC8465569 DOI: 10.3390/genes12091353] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/22/2021] [Accepted: 08/27/2021] [Indexed: 01/04/2023] Open
Abstract
Bardet-Biedl Syndrome is a rare non-motile primary ciliopathy with multisystem involvement and autosomal recessive inheritance. The clinical picture is extremely polymorphic. The main clinical features are retinal cone-rod dystrophy, central obesity, postaxial polydactyly, cognitive impairment, hypogonadism and genitourinary abnormalities, and kidney disease. It is caused by various types of mutations, mainly in genes encoding BBSome proteins, chaperonins, and IFT complex. Variable expressivity and pleiotropy are correlated with the existence of multiple genes and variants modifiers. This review is focused on the phenomena of heterogeneity (locus, allelic, mutational, and clinical) in Bardet-Biedl Syndrome, its mechanisms, and importance in early diagnosis and proper management.
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11
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Lauri A, Fasano G, Venditti M, Dallapiccola B, Tartaglia M. In vivo Functional Genomics for Undiagnosed Patients: The Impact of Small GTPases Signaling Dysregulation at Pan-Embryo Developmental Scale. Front Cell Dev Biol 2021; 9:642235. [PMID: 34124035 PMCID: PMC8194860 DOI: 10.3389/fcell.2021.642235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/12/2021] [Indexed: 12/24/2022] Open
Abstract
While individually rare, disorders affecting development collectively represent a substantial clinical, psychological, and socioeconomic burden to patients, families, and society. Insights into the molecular mechanisms underlying these disorders are required to speed up diagnosis, improve counseling, and optimize management toward targeted therapies. Genome sequencing is now unveiling previously unexplored genetic variations in undiagnosed patients, which require functional validation and mechanistic understanding, particularly when dealing with novel nosologic entities. Functional perturbations of key regulators acting on signals' intersections of evolutionarily conserved pathways in these pathological conditions hinder the fine balance between various developmental inputs governing morphogenesis and homeostasis. However, the distinct mechanisms by which these hubs orchestrate pathways to ensure the developmental coordinates are poorly understood. Integrative functional genomics implementing quantitative in vivo models of embryogenesis with subcellular precision in whole organisms contribute to answering these questions. Here, we review the current knowledge on genes and mechanisms critically involved in developmental syndromes and pediatric cancers, revealed by genomic sequencing and in vivo models such as insects, worms and fish. We focus on the monomeric GTPases of the RAS superfamily and their influence on crucial developmental signals and processes. We next discuss the effectiveness of exponentially growing functional assays employing tractable models to identify regulatory crossroads. Unprecedented sophistications are now possible in zebrafish, i.e., genome editing with single-nucleotide precision, nanoimaging, highly resolved recording of multiple small molecules activity, and simultaneous monitoring of brain circuits and complex behavioral response. These assets permit accurate real-time reporting of dynamic small GTPases-controlled processes in entire organisms, owning the potential to tackle rare disease mechanisms.
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Affiliation(s)
- Antonella Lauri
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | | | | | | | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
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12
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Bernatik O, Paclikova P, Kotrbova A, Bryja V, Cajanek L. Primary Cilia Formation Does Not Rely on WNT/β-Catenin Signaling. Front Cell Dev Biol 2021; 9:623753. [PMID: 33718363 PMCID: PMC7952446 DOI: 10.3389/fcell.2021.623753] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/04/2021] [Indexed: 11/13/2022] Open
Abstract
Primary cilia act as crucial regulators of embryo development and tissue homeostasis. They are instrumental for modulation of several signaling pathways, including Hedgehog, WNT, and TGF-β. However, gaps exist in our understanding of how cilia formation and function is regulated. Recent work has implicated WNT/β-catenin signaling pathway in the regulation of ciliogenesis, yet the results are conflicting. One model suggests that WNT/β-catenin signaling negatively regulates cilia formation, possibly via effects on cell cycle. In contrast, second model proposes a positive role of WNT/β-catenin signaling on cilia formation, mediated by the re-arrangement of centriolar satellites in response to phosphorylation of the key component of WNT/β-catenin pathway, β-catenin. To clarify these discrepancies, we investigated possible regulation of primary cilia by the WNT/β-catenin pathway in cell lines (RPE-1, NIH3T3, and HEK293) commonly used to study ciliogenesis. We used WNT3a to activate or LGK974 to block the pathway, and examined initiation of ciliogenesis, cilium length, and percentage of ciliated cells. We show that the treatment by WNT3a has no- or lesser inhibitory effect on cilia formation. Importantly, the inhibition of secretion of endogenous WNT ligands using LGK974 blocks WNT signaling but does not affect ciliogenesis. Finally, using knock-out cells for key WNT pathway components, namely DVL1/2/3, LRP5/6, or AXIN1/2 we show that neither activation nor deactivation of the WNT/β-catenin pathway affects the process of ciliogenesis. These results suggest that WNT/β-catenin-mediated signaling is not generally required for efficient cilia formation. In fact, activation of the WNT/β-catenin pathway in some systems seems to moderately suppress ciliogenesis.
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Affiliation(s)
- Ondrej Bernatik
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Petra Paclikova
- Section of Animal Physiology and Immunology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Anna Kotrbova
- Section of Animal Physiology and Immunology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Vitezslav Bryja
- Section of Animal Physiology and Immunology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Lukas Cajanek
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno, Czechia
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13
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Liu YX, Xue B, Sun WY, Wingfield JL, Sun J, Wu M, Lechtreck KF, Wu Z, Fan ZC. Bardet-Biedl syndrome 3 protein promotes ciliary exit of the signaling protein phospholipase D via the BBSome. eLife 2021; 10:59119. [PMID: 33587040 PMCID: PMC7963478 DOI: 10.7554/elife.59119] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 02/13/2021] [Indexed: 12/13/2022] Open
Abstract
Certain ciliary signaling proteins couple with the BBSome, a conserved complex of Bardet–Biedl syndrome (BBS) proteins, to load onto retrograde intraflagellar transport (IFT) trains for their removal out of cilia in Chlamydomonas reinhardtii. Here, we show that loss of the Arf-like 6 (ARL6) GTPase BBS3 causes the signaling protein phospholipase D (PLD) to accumulate in cilia. Upon targeting to the basal body, BBSomes enter and cycle through cilia via IFT, while BBS3 in a GTP-bound state separates from BBSomes, associates with the membrane, and translocates from the basal body to cilia by diffusion. Upon arriving at the ciliary tip, GTP-bound BBS3 binds and recruits BBSomes to the ciliary membrane for interacting with PLD, thus making the PLD-laden BBSomes available to load onto retrograde IFT trains for ciliary exit. Therefore, BBS3 promotes PLD exit from cilia via the BBSome, providing a regulatory mechanism for ciliary signaling protein removal out of cilia.
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Affiliation(s)
- Yan-Xia Liu
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Bin Xue
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Wei-Yue Sun
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Jenna L Wingfield
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Jun Sun
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Mingfu Wu
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, United States
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Zhenlong Wu
- State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, China
| | - Zhen-Chuan Fan
- State Key Laboratory of Food Nutrition and Safety, Institute of Health Biotechnology, Tianjin University of Science and Technology, Tianjin, China
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14
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Wu L, Song J, Xue J, Xiao T, Wei Q, Zhang Z, Zhang Y, Li Z, Hu Y, Zhang G, Xia H, Li J, Yang X, Liu Q. MircoRNA-143-3p regulating ARL6 is involved in the cadmium-induced inhibition of osteogenic differentiation in human bone marrow mesenchymal stem cells. Toxicol Lett 2020; 331:159-166. [DOI: 10.1016/j.toxlet.2020.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 04/16/2020] [Accepted: 06/03/2020] [Indexed: 12/20/2022]
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15
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Lin SJ, Huang CF, Wu TS, Li CC, Lee FJS. Arl4D-EB1 interaction promotes centrosomal recruitment of EB1 and microtubule growth. Mol Biol Cell 2020; 31:2348-2362. [PMID: 32755434 PMCID: PMC7851962 DOI: 10.1091/mbc.e18-10-0611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
ADP-ribosylation factor (Arf)-like 4D (Arl4D), one of the Arf-like small GTPases, functions in the regulation of cell morphology, cell migration, and actin cytoskeleton remodeling. End-binding 1 (EB1) is a microtubule (MT) plus-end tracking protein that preferentially localizes at the tips of the plus ends of growing MTs and at the centrosome. EB1 depletion results in many centrosome-related defects. Here, we report that Arl4D promotes the recruitment of EB1 to the centrosome and regulates MT nucleation. We first showed that Arl4D interacts with EB1 in a GTP-dependent manner. This interaction is dependent on the C-terminal EB homology region of EB1 and partially dependent on an SxLP motif of Arl4D. We found that Arl4D colocalized with γ-tubulin in centrosomes and the depletion of Arl4D resulted in a centrosomal MT nucleation defect. We further demonstrated that abolishing Arl4D-EB1 interaction decreased MT nucleation rate and diminished the centrosomal recruitment of EB1 without affecting MT growth rate. In addition, Arl4D binding to EB1 increased the association between the p150 subunit of dynactin and the EB1, which is important for MT stabilization. Together, our results indicate that Arl4D modulates MT nucleation through regulation of the EB1–p150 association at the centrosome.
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Affiliation(s)
- Shin-Jin Lin
- Institute of Molecular Medicine, National Taiwan University, 100225 Taipei, Taiwan.,Department of Medical Research, National Taiwan University Hospital, National Taiwan University, 100225 Taipei, Taiwan
| | - Chun-Fang Huang
- Institute of Molecular Medicine, National Taiwan University, 100225 Taipei, Taiwan
| | - Tsung-Sheng Wu
- Institute of Molecular Medicine, National Taiwan University, 100225 Taipei, Taiwan
| | - Chun-Chun Li
- Institute of Molecular Medicine, National Taiwan University, 100225 Taipei, Taiwan
| | - Fang-Jen S Lee
- Institute of Molecular Medicine, National Taiwan University, 100225 Taipei, Taiwan.,Center of Precision Medicine, College of Medicine, National Taiwan University, 100225 Taipei, Taiwan.,Department of Medical Research, National Taiwan University Hospital, National Taiwan University, 100225 Taipei, Taiwan
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16
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Fisher S, Kuna D, Caspary T, Kahn RA, Sztul E. ARF family GTPases with links to cilia. Am J Physiol Cell Physiol 2020; 319:C404-C418. [PMID: 32520609 PMCID: PMC7500214 DOI: 10.1152/ajpcell.00188.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The ADP-ribosylation factor (ARF) superfamily of regulatory GTPases, including both the ARF and ARF-like (ARL) proteins, control a multitude of cellular functions, including aspects of vesicular traffic, lipid metabolism, mitochondrial architecture, the assembly and dynamics of the microtubule and actin cytoskeletons, and other pathways in cell biology. Considering their general utility, it is perhaps not surprising that increasingly ARF/ARLs have been found in connection to primary cilia. Here, we critically evaluate the current knowledge of the roles four ARF/ARLs (ARF4, ARL3, ARL6, ARL13B) play in cilia and highlight key missing information that would help move our understanding forward. Importantly, these GTPases are themselves regulated by guanine nucleotide exchange factors (GEFs) that activate them and by GTPase-activating proteins (GAPs) that act as both effectors and terminators of signaling. We believe that the identification of the GEFs and GAPs and better models of the actions of these GTPases and their regulators will provide a much deeper understanding and appreciation of the mechanisms that underly ciliary functions and the causes of a number of human ciliopathies.
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Affiliation(s)
- Skylar Fisher
- 1Department of Biochemistry, Emory University
School of Medicine, Atlanta,
Georgia
| | - Damian Kuna
- 2Department of Cell, Developmental and Integrative
Biology, University of Alabama at Birmingham,
Birmingham, Alabama
| | - Tamara Caspary
- 3Department of Human Genetics, Emory
University School of Medicine, Atlanta,
Georgia
| | - Richard A. Kahn
- 1Department of Biochemistry, Emory University
School of Medicine, Atlanta,
Georgia
| | - Elizabeth Sztul
- 2Department of Cell, Developmental and Integrative
Biology, University of Alabama at Birmingham,
Birmingham, Alabama
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17
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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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18
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Heigwer J, Kutzner J, Haeussler M, Burkhalter MD, Draebing T, Juergensen L, Katus HA, Philipp M, Westhoff JH, Hassel D. miR-103/107 regulates left-right asymmetry in zebrafish by modulating Kupffer's vesicle development and ciliogenesis. Biochem Biophys Res Commun 2020; 527:432-439. [PMID: 32334837 DOI: 10.1016/j.bbrc.2020.04.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 04/15/2020] [Indexed: 10/24/2022]
Abstract
In zebrafish, cilia movement within the Kupffer's vesicle (KV) generates a fluid flow responsible for accumulating nodal signals exclusively in the left lateral plate mesoderm, thereby initiating left-right patterning (LRP). Defects in LRP cause devastating congenital disorders including congenital heart malformations due to organ mis-positioning. We identified the miR-103/107 family to be involved in regulating LRP. Depletion of miR-103/107 in zebrafish embryos resulted in malpositioned and malformed visceral organs and hearts due to disturbed LRP gene expression, indicating early defects in LRP. Additionally, loss of miR-103/107 affected KV morphogenesis and cilia formation without disturbing endoderm development. Human fibroblasts depleted of miR-103a/107 often failed to extend cilia or developed shorter cilia, indicating functional conservation between species. We identified arl6, araf and foxH1 as direct targets of miR-103/107 providing a mechanistic link to cilia development and nodal signal titration. We describe a new microRNA family controlling KV development and hence influencing establishment of internal organ asymmetry.
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Affiliation(s)
- Jana Heigwer
- Department of Internal Medicine III, Cardiology, Heidelberg University Hospital, 69120, Heidelberg, Germany and DZHK (German Centre for Cardiovascular Research), Partner Site, Heidelberg, Mannheim, Germany; Department of Pediatrics I, University Children's Hospital Heidelberg, 69120, Heidelberg, Germany.
| | - Juliane Kutzner
- Department of Internal Medicine III, Cardiology, Heidelberg University Hospital, 69120, Heidelberg, Germany and DZHK (German Centre for Cardiovascular Research), Partner Site, Heidelberg, Mannheim, Germany
| | - Monika Haeussler
- Institute of Biochemistry and Molecular Biology (iBMB), Ulm University, 89081, Ulm, Germany
| | - Martin D Burkhalter
- Institute of Biochemistry and Molecular Biology (iBMB), Ulm University, 89081, Ulm, Germany; Department of Experimental and Clinical Pharmacology and Pharmacogenomics, University Hospital Tübingen, 72074, Tübingen, Germany
| | - Thomas Draebing
- Department of Internal Medicine III, Cardiology, Heidelberg University Hospital, 69120, Heidelberg, Germany and DZHK (German Centre for Cardiovascular Research), Partner Site, Heidelberg, Mannheim, Germany
| | - Lonny Juergensen
- Department of Internal Medicine III, Cardiology, Heidelberg University Hospital, 69120, Heidelberg, Germany and DZHK (German Centre for Cardiovascular Research), Partner Site, Heidelberg, Mannheim, Germany
| | - Hugo A Katus
- Department of Internal Medicine III, Cardiology, Heidelberg University Hospital, 69120, Heidelberg, Germany and DZHK (German Centre for Cardiovascular Research), Partner Site, Heidelberg, Mannheim, Germany
| | - Melanie Philipp
- Institute of Biochemistry and Molecular Biology (iBMB), Ulm University, 89081, Ulm, Germany; Department of Experimental and Clinical Pharmacology and Pharmacogenomics, University Hospital Tübingen, 72074, Tübingen, Germany
| | - Jens H Westhoff
- Department of Pediatrics I, University Children's Hospital Heidelberg, 69120, Heidelberg, Germany
| | - David Hassel
- Department of Internal Medicine III, Cardiology, Heidelberg University Hospital, 69120, Heidelberg, Germany and DZHK (German Centre for Cardiovascular Research), Partner Site, Heidelberg, Mannheim, Germany
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19
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Powell L, Samarakoon YH, Ismail S, Sayer JA. ARL3, a small GTPase with a functionally conserved role in primary cilia and immune synapses. Small GTPases 2019; 12:167-176. [PMID: 31826708 DOI: 10.1080/21541248.2019.1703466] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The primary cilium and the immunological synapse are both specialized functional plasma membrane domains that share several similarities. Signalling output of membrane domains is regulated, spatially and temporally, by segregating and focusing lipids and proteins. ARL3, a small GTPase, plays a major role in concentrating lipid-modified proteins in both the immunological synapse and the primary cilia. Here in this review we will introduce the role of ARL3 in health and disease and its role in polarizing signalling at the primary cilia and immunological synapses.
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Affiliation(s)
- Laura Powell
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, International Centre for Life, Newcastle upon Tyne, UK
| | - Youhani H Samarakoon
- Spatial segregation of signalling Lab, Beatson Institute for Cancer Research, Glasgow, UK.,Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Shehab Ismail
- Spatial segregation of signalling Lab, Beatson Institute for Cancer Research, Glasgow, UK.,Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - John A Sayer
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, International Centre for Life, Newcastle upon Tyne, UK.,Renal Services, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.,NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne, UK
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20
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Lodh S. Primary Cilium, An Unsung Hero in Maintaining Functional β-cell Population. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:471-480. [PMID: 31543709 PMCID: PMC6747938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
A primary challenge in type 2 diabetes (T2D) is the preservation of a functional population of β-cells, which play a central role in regulating blood glucose levels. Two congenital disorders, Bardet-Biedl syndrome (BBS) and Alström syndrome (ALMS), can serve as useful models to understand how β-cells are normally produced and regenerated. Both are characterized by obesity, loss of β-cells, and defects in primary cilia - the sensory center of cells. Primary cilia are cellular protrusions present in almost every vertebrate cell. This antenna-like organelle plays a crucial role in regulating several signaling pathways that direct proper development, proliferation, and homeostasis. Mutations in genes expressing ciliary proteins or proteins present at or near the base of the cilium lead to disorders, collectively called ciliopathies. BBS and Alström syndrome are such disorders. Though both BBS and Alström patients are obese, their childhood diabetes rates are vastly different, suggesting distinct pathogenesis underlying these two ciliopathies. Clinical studies suggest that BBS patients are protected against early onset diabetes by sustained or enhanced β-cell function. In contrast, Alström patients are more prone to develop diabetes. They have hyperinsulinemia, yet their β-cells fail to sense glucose and to regulate insulin secretion accordingly. These data suggest a potential role for primary cilia in maintaining a functional β-cell population and that defects in cilia or in ciliary proteins impair development and function of β-cells. Identifying the respective roles of primary cilia and ciliary proteins, such as BBS and ALMS1 may shed light on β-cell biology and uncover potentially novel targets for diabetes therapy.
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Affiliation(s)
- Sukanya Lodh
- To whom all correspondence should be addressed: Sukanya Lodh, Department of Biological sciences, Marquette University, 1428 W. Clybourn St., Milwaukee, WI 53233; Tel: 802-881-6221, Email address:
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21
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Hor CH, Goh EL. Small GTPases in hedgehog signalling: emerging insights into the disease mechanisms of Rab23-mediated and Arl13b-mediated ciliopathies. Curr Opin Genet Dev 2019; 56:61-68. [PMID: 31465935 DOI: 10.1016/j.gde.2019.07.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 01/31/2023]
Abstract
Small GTPases are known to have pivotal roles in intracellular trafficking, and several members of the small GTPases superfamily such as Rab10 [1,2•], Rab11 [3-5], Rab34 [6•,7], Rab8 [3,8], Rab23 [9-12], RSG1 [13-15], Arl13b [16-22], and Arl6 [22,23] were recently reported to mediate primary cilia function and/or Hh signalling. Although these functions are implicated in diseases such as ciliopathies, the molecular basis underlying how these small GTPases mediate primary cilia-dependent Hh signalling and pathogenesis of ciliopathies warrants further investigations. Notably, Rab23 and Arl13b have been implicated in ciliopathy-associated human diseases and could regulate Hh signalling cascade in multifaceted manners. This review thus specifically discuss the roles of Rab23 and Arl13b in primary cilia of mammalian systems, their cilia-dependent and cilia-independent modulation of hedgehog signalling pathways and their implications in Carpenter Syndrome and Joubert Syndrome respectively.
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Affiliation(s)
- Catherine Hh Hor
- Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore 169857, Singapore; Department of Chemistry, Research Cluster on Health and Drug Discovery, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong
| | - Eyleen Lk Goh
- Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore 169857, Singapore; Department of Research, National Neuroscience Institute, Singapore 308433, Singapore; Neuroscience and Mental Health Faculty, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 308232, Singapore; KK Research Center, KK Women's and Children's Hospital, Singapore 229899, Singapore.
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22
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Deretic D, Lorentzen E, Fresquez T. The ins and outs of the Arf4-based ciliary membrane-targeting complex. Small GTPases 2019; 12:1-12. [PMID: 31068062 DOI: 10.1080/21541248.2019.1616355] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The small GTPase Arf4-based ciliary membrane-targeting complex recognizes specific targeting signals within sensory receptors and regulates their directed movement to primary cilia. Activated Arf4 directly binds the VxPx ciliary-targeting signal (CTS) of the light-sensing receptor rhodopsin. Recent findings revealed that at the trans-Golgi, marked by the small GTPase Rab6, activated Arf4 forms a functional complex with rhodopsin and the Arf guanine nucleotide exchange factor (GEF) GBF1, providing positive feedback that drives further Arf4 activation in ciliary trafficking. Arf4 function is conserved across diverse cell types; however, it appears that not all its aspects are conserved across species, as mouse Arf4 is a natural mutant in the conserved α3 helix, which is essential for its interaction with rhodopsin. Generally, activated Arf4 regulates the assembly of the targeting nexus containing the Arf GAP ASAP1 and the Rab11a-FIP3-Rabin8 dual effector complex, which controls the assembly of the highly conserved Rab11a-Rabin8-Rab8 ciliary-targeting module. It was recently found that this module interacts with the R-SNARE VAMP7, likely in its activated, c-Src-phosphorylated form. Rab11 and Rab8 bind VAMP7 regulatory longin domain (LD), whereas Rabin8 interacts with the SNARE domain, capturing VAMP7 for delivery to the ciliary base and subsequent pairing with the cognate SNAREs syntaxin 3 and SNAP-25. This review will focus on the implications of these novel findings that further illuminate the role of well-ordered Arf and Rab interaction networks in targeting of sensory receptors to primary cilia. Abbreviations: CTS: Ciliary-Targeting Signal; GAP: GTPase Activating Protein; GEF: Guanine Nucleotide Exchange Factor; RTC(s), Rhodopsin Transport Carrier(s); SNARE: Soluble N-ethylmaleimide-sensitive Factor Attachment Protein Receptor; TGN: Trans-Golgi Network.
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Affiliation(s)
- Dusanka Deretic
- Departments of Surgery, Division of Ophthalmology, University of New Mexico , Albuquerque, NM, USA.,Cell Biology and Physiology, University of New Mexico , Albuquerque, NM, USA
| | - Esben Lorentzen
- Department of Molecular Biology and Genetics, Aarhus University , Aarhus, Denmark
| | - Theresa Fresquez
- Departments of Surgery, Division of Ophthalmology, University of New Mexico , Albuquerque, NM, USA
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23
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Sztul E, Chen PW, Casanova JE, Cherfils J, Dacks JB, Lambright DG, Lee FJS, Randazzo PA, Santy LC, Schürmann A, Wilhelmi I, Yohe ME, Kahn RA. ARF GTPases and their GEFs and GAPs: concepts and challenges. Mol Biol Cell 2019; 30:1249-1271. [PMID: 31084567 PMCID: PMC6724607 DOI: 10.1091/mbc.e18-12-0820] [Citation(s) in RCA: 149] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/26/2019] [Accepted: 03/11/2019] [Indexed: 12/12/2022] Open
Abstract
Detailed structural, biochemical, cell biological, and genetic studies of any gene/protein are required to develop models of its actions in cells. Studying a protein family in the aggregate yields additional information, as one can include analyses of their coevolution, acquisition or loss of functionalities, structural pliability, and the emergence of shared or variations in molecular mechanisms. An even richer understanding of cell biology can be achieved through evaluating functionally linked protein families. In this review, we summarize current knowledge of three protein families: the ARF GTPases, the guanine nucleotide exchange factors (ARF GEFs) that activate them, and the GTPase-activating proteins (ARF GAPs) that have the ability to both propagate and terminate signaling. However, despite decades of scrutiny, our understanding of how these essential proteins function in cells remains fragmentary. We believe that the inherent complexity of ARF signaling and its regulation by GEFs and GAPs will require the concerted effort of many laboratories working together, ideally within a consortium to optimally pool information and resources. The collaborative study of these three functionally connected families (≥70 mammalian genes) will yield transformative insights into regulation of cell signaling.
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Affiliation(s)
- Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Pei-Wen Chen
- Department of Biology, Williams College, Williamstown, MA 01267
| | - James E. Casanova
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908
| | - Jacqueline Cherfils
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS and Ecole Normale Supérieure Paris-Saclay, 94235 Cachan, France
| | - Joel B. Dacks
- Division of Infectious Disease, Department of Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - David G. Lambright
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Amherst, MA 01605
| | - Fang-Jen S. Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | | | - Lorraine C. Santy
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802
| | - Annette Schürmann
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Ilka Wilhelmi
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Marielle E. Yohe
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322-3050
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24
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Insinna C, Lu Q, Teixeira I, Harned A, Semler EM, Stauffer J, Magidson V, Tiwari A, Kenworthy AK, Narayan K, Westlake CJ. Investigation of F-BAR domain PACSIN proteins uncovers membrane tubulation function in cilia assembly and transport. Nat Commun 2019; 10:428. [PMID: 30683896 PMCID: PMC6347608 DOI: 10.1038/s41467-018-08192-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 12/20/2018] [Indexed: 12/03/2022] Open
Abstract
The intracellular ciliogenesis pathway requires membrane trafficking, fusion, and reorganization. Here, we demonstrate in human cells and zebrafish that the F-BAR domain containing proteins PACSIN1 and -2 play an essential role in ciliogenesis, similar to their binding partner and membrane reorganizer EHD1. In mature cilia, PACSINs and EHDs are dynamically localized to the ciliary pocket membrane (CPM) and transported away from this structure on membrane tubules along with proteins that exit the cilium. PACSINs function early in ciliogenesis at the ciliary vesicle (CV) stage to promote mother centriole to basal body transition. Remarkably, we show that PACSIN1 and EHD1 assemble membrane t7ubules from the developing intracellular cilium that attach to the plasma membrane, creating an extracellular membrane channel (EMC) to the outside of the cell. Together, our work uncovers a function for F-BAR proteins and membrane tubulation in ciliogenesis and explains how the intracellular cilium emerges from the cell.
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Affiliation(s)
- Christine Insinna
- Laboratory of Cellular and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Quanlong Lu
- Laboratory of Cellular and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Isabella Teixeira
- Laboratory of Cellular and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Adam Harned
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21701, USA
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Elizabeth M Semler
- Laboratory of Cellular and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Jim Stauffer
- Laboratory of Cellular and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Valentin Magidson
- Laboratory of Cellular and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Ajit Tiwari
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Anne K Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Kedar Narayan
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21701, USA
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Christopher J Westlake
- Laboratory of Cellular and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA.
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25
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Tamura R, Nakaoka H, Yoshihara K, Mori Y, Yachida N, Nishikawa N, Motoyama T, Okuda S, Inoue I, Enomoto T. Novel MXD4-NUTM1 fusion transcript identified in primary ovarian undifferentiated small round cell sarcoma. Genes Chromosomes Cancer 2018; 57:557-563. [PMID: 30338611 PMCID: PMC6221051 DOI: 10.1002/gcc.22668] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 06/21/2018] [Accepted: 07/04/2018] [Indexed: 12/20/2022] Open
Abstract
Primary ovarian sarcomas are extremely rare tumors, and their genomic and transcriptomic alterations remain to be elucidated. We performed whole exome sequencing of primary tumor and matched normal blood samples derived from one patient with ovarian undifferentiated small round cell sarcoma. We identified 8 nonsynonymous somatic mutations, and all mutations were missense or nonsense changes. Next, we performed RNA sequencing of the tumor sample and identified two in-frame fusion transcripts: MXD4-NUTM1 and ARL6-POT1. Most NUTM1 exons were retained in the MXD4-NUTM1 fusion transcript, and we confirmed an increase in NUTM1 mRNA and protein expression in tumor tissue. Further genomic and transcriptomic analyses might lead to the development of new therapeutic strategies based on the molecular characteristics of ovarian undifferentiated small round cell sarcoma.
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Affiliation(s)
- Ryo Tamura
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Hirofumi Nakaoka
- Division of Human GeneticsNational Institute of GeneticsMishimaJapan
| | - Kosuke Yoshihara
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Yutaro Mori
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Nozomi Yachida
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Nobumichi Nishikawa
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Teiichi Motoyama
- Department of Molecular and Diagnostic PathologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Shujiro Okuda
- Department of BioinformaticsNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Ituro Inoue
- Division of Human GeneticsNational Institute of GeneticsMishimaJapan
| | - Takayuki Enomoto
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
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Song P, Perkins BD. Developmental expression of the zebrafish Arf-like small GTPase paralogs arl13a and arl13b. Gene Expr Patterns 2018; 29:82-87. [PMID: 30009987 DOI: 10.1016/j.gep.2018.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 07/10/2018] [Accepted: 07/12/2018] [Indexed: 12/13/2022]
Abstract
Members of the Arf-like (Arl) family of small GTP-binding proteins regulate a number of cellular functions and play important roles in cilia structure and signaling. The small GTPase Arl13a is a close paralog to Arl13b, a small GTPase required for normal cilia formation that causes Joubert Syndrome when mutated. As mutation of arl13b causes a slow retinal degeneration in zebrafish (Song et al., 2016), we hypothesized that expression of arl13a may provide functional redundancy. We determined the expression domains of arl13a and arl13b during zebrafish development and examined subcellular localization by expression of fluorescence fusion proteins. Both genes are widely expressed during early cell division and gastrulation and Arl13a and Arl13b both localize to microtubules in ciliated and dividing cells of the early zebrafish embryo. Between 2 and 5 days post fertilization (dpf), arl13b is expressed in neural tissues while expression of arl13a is downregulated by 2 dpf and restricted to craniofacial structures. These results indicate that arl13a and arl13b have evolved different roles and that arl13a does not function in the zebrafish retina.
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Affiliation(s)
- Ping Song
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Brian D Perkins
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.
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Oshikane H, Watabe M, Kikuchi-Utsumi K, Nakaki T. Rab1a rescues the toxicity of PRAF3. Biochem Biophys Rep 2018; 14:16-19. [PMID: 29872729 PMCID: PMC5986628 DOI: 10.1016/j.bbrep.2018.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/07/2018] [Accepted: 03/16/2018] [Indexed: 11/15/2022] Open
Abstract
The PRA1-superfamily member PRAF3 plays pivotal roles in membrane traffic as a GDI displacement factor via physical interaction with a variety of Rab proteins, as well as in the modulation of antioxidant glutathione through its interaction with EAAC1 (SLC1A1). Overproduction of PRAF3 is known to be toxic to the host cells, although the factors capable of cancelling the toxicity remained unknown. We here show that Rab1a can rescue the cytotoxicity caused by PRAF3 possibly by “positively” regulating ER-Golgi trafficking, cancelling the “negative” modulation by PRAF3. Our results illuminate the close physiological relationship between PRAF3 and Rab proteins. PRAF3 exhibits cytotoxicity both in yeast and human cells. Among Rabs, only Rab1a can rescue the toxicity of PRAF3. PRAF3 expression may be strictly regulated in accordance with Rab1a expression.
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Affiliation(s)
- Hiroyuki Oshikane
- Department of Pharmacology, Teikyo University School of Medicine, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan
| | - Masahiko Watabe
- Department of Pharmacology, Teikyo University School of Medicine, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan.,General Medical Education and Research Center (G-MEC), Teikyo University, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan
| | - Kazue Kikuchi-Utsumi
- Department of Pharmacology, Teikyo University School of Medicine, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan
| | - Toshio Nakaki
- Department of Pharmacology, Teikyo University School of Medicine, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan
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28
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Wheway G, Nazlamova L, Hancock JT. Signaling through the Primary Cilium. Front Cell Dev Biol 2018; 6:8. [PMID: 29473038 PMCID: PMC5809511 DOI: 10.3389/fcell.2018.00008] [Citation(s) in RCA: 294] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
The presence of single, non-motile “primary” cilia on the surface of epithelial cells has been well described since the 1960s. However, for decades these organelles were believed to be vestigial, with no remaining function, having lost their motility. It wasn't until 2003, with the discovery that proteins responsible for transport along the primary cilium are essential for hedgehog signaling in mice, that the fundamental importance of primary cilia in signal transduction was realized. Little more than a decade later, it is now clear that the vast majority of signaling pathways in vertebrates function through the primary cilium. This has led to the adoption of the term “the cells's antenna” as a description for the primary cilium. Primary cilia are particularly important during development, playing fundamental roles in embryonic patterning and organogenesis, with a suite of inherited developmental disorders known as the “ciliopathies” resulting from mutations in genes encoding cilia proteins. This review summarizes our current understanding of the role of these fascinating organelles in a wide range of signaling pathways.
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Affiliation(s)
- Gabrielle Wheway
- Department of Applied Science, Faculty of Health and Applied Sciences, Centre for Research in Biosciences, University of the West of England, Bristol, United Kingdom
| | - Liliya Nazlamova
- Department of Applied Science, Faculty of Health and Applied Sciences, Centre for Research in Biosciences, University of the West of England, Bristol, United Kingdom
| | - John T Hancock
- Department of Applied Science, Faculty of Health and Applied Sciences, Centre for Research in Biosciences, University of the West of England, Bristol, United Kingdom
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Hsu Y, Garrison JE, Kim G, Schmitz AR, Searby CC, Zhang Q, Datta P, Nishimura DY, Seo S, Sheffield VC. BBSome function is required for both the morphogenesis and maintenance of the photoreceptor outer segment. PLoS Genet 2017; 13:e1007057. [PMID: 29049287 PMCID: PMC5663628 DOI: 10.1371/journal.pgen.1007057] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/31/2017] [Accepted: 10/08/2017] [Indexed: 01/19/2023] Open
Abstract
Genetic mutations disrupting the structure and function of primary cilia cause various inherited retinal diseases in humans. Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, pleiotropic ciliopathy characterized by retinal degeneration, obesity, postaxial polydactyly, intellectual disability, and genital and renal abnormalities. To gain insight into the mechanisms of retinal degeneration in BBS, we developed a congenital knockout mouse of Bbs8, as well as conditional mouse models in which function of the BBSome (a protein complex that mediates ciliary trafficking) can be temporally inactivated or restored. We demonstrate that BBS mutant mice have defects in retinal outer segment morphogenesis. We further demonstrate that removal of Bbs8 in adult mice affects photoreceptor function and disrupts the structural integrity of the outer segment. Notably, using a mouse model in which a gene trap inhibiting Bbs8 gene expression can be removed by an inducible FLP recombinase, we show that when BBS8 is restored in immature retinas with malformed outer segments, outer segment extension can resume normally and malformed outer segment discs are displaced distally by normal outer segment structures. Over time, the retinas of the rescued mice become morphologically and functionally normal, indicating that there is a window of plasticity when initial retinal outer segment morphogenesis defects can be ameliorated. The BBSome is a protein complex that regulates ciliary trafficking in primary cilia, and mutations that impair BBSome function cause Bardet-Biedl Syndrome (BBS). BBS patients have retinal degeneration leading to blindness, but the disease pathophysiology has not been fully elucidated. In this study, we found that the BBSome is necessary for the structural organization of photoreceptor outer segments, and that the loss of different functional BBSome subunits causes outer segment malformation. Using a mouse model that allows the temporal inactivation of the BBSome, we inactivated BBSome function after the outer segment had formed normally. We found that the BBSome is required for both the initial formation and the continual maintenance of outer segment structures throughout life. In addition, using a mouse model that allows the temporal restoration of the BBSome, we restored BBSome function in immature photoreceptors and show that the malformed outer segment discs are displaced distally by normally formed outer segment structures. This finding indicates that when gene function is restored in immature retinas shortly after initial outer segment malformation, morphologically normal outer segments and a functionally normal retina can still result. This study has important implications for the timing of treatment of human retinal diseases.
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Affiliation(s)
- Ying Hsu
- Interdisciplinary Graduate Program in Molecular Medicine, University of Iowa, Iowa City, Iowa, United States
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
| | - Janelle E. Garrison
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
| | - Gunhee Kim
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
| | - Addison R. Schmitz
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
| | - Charles C. Searby
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
| | - Qihong Zhang
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
| | - Poppy Datta
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Darryl Y. Nishimura
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
| | - Seongjin Seo
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - Val C. Sheffield
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
- * E-mail:
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Wang J, Fresquez T, Kandachar V, Deretic D. The Arf GEF GBF1 and Arf4 synergize with the sensory receptor cargo, rhodopsin, to regulate ciliary membrane trafficking. J Cell Sci 2017; 130:3975-3987. [PMID: 29025970 DOI: 10.1242/jcs.205492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 10/10/2017] [Indexed: 01/05/2023] Open
Abstract
The small GTPase Arf4 and the Arf GTPase-activating protein (GAP) ASAP1 cooperatively sequester sensory receptor cargo into transport carriers targeted to primary cilia, but the input that drives Arf4 activation in this process remains unknown. Here, we show, by using frog retinas and recombinant human proteins, that during the carrier biogenesis from the photoreceptor Golgi/trans-Golgi network (TGN) a functional complex is formed between Arf4, the Arf guanine nucleotide exchange factor (GEF) GBF1 and the light-sensing receptor, rhodopsin. Rhodopsin and Arf4 bind the regulatory N-terminal dimerization and cyclophillin-binding (DCB)-homology upstream of Sec7 (HUS) domain of GBF1. The complex is sensitive to Golgicide A (GCA), a selective inhibitor of GBF1 that accordingly blocks rhodopsin delivery to the cilia, without disrupting the photoreceptor Golgi. The emergence of newly synthesized rhodopsin in the endomembrane system is essential for GBF1-Arf4 complex formation in vivo Notably, GBF1 interacts with the Arf GAP ASAP1 in a GCA-resistant manner. Our findings indicate that converging signals on GBF1 from the influx of cargo into the Golgi/TGN and the feedback from Arf4, combined with input from ASAP1, control Arf4 activation during sensory membrane trafficking to primary cilia.
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Affiliation(s)
- Jing Wang
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Theresa Fresquez
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Vasundhara Kandachar
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Dusanka Deretic
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA .,Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico 87131, USA
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Jean F, Pilgrim D. Coordinating the uncoordinated: UNC119 trafficking in cilia. Eur J Cell Biol 2017; 96:643-652. [PMID: 28935136 DOI: 10.1016/j.ejcb.2017.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/25/2017] [Accepted: 09/05/2017] [Indexed: 12/29/2022] Open
Abstract
Constructing the distinct subcellular environment of the cilium relies in a large part upon intraflagellar transport (IFT) proteins, which traffic cargo both to and within the cilium. However, evidence from the last 10 years suggests that IFT alone is not sufficient to generate the ciliary environment. One essential factor is UNC119, which interacts with known IFT molecular switches to transport ciliary cargos. Despite its apparent importance in ciliary trafficking though, human UNC119 mutations have only rarely been associated with diseases commonly linked with ciliopathies. This review will outline the trafficking pathways required for constructing the cilium by highlighting UNC119's role and the complexities involved in ciliary trafficking. Finally, despite important roles for UNC119 in cilia, UNC119 proteins also interact with non-ciliary proteins to affect other cellular processes.
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32
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Priya S, Nampoothiri S, Sen P, Sripriya S. Bardet-Biedl syndrome: Genetics, molecular pathophysiology, and disease management. Indian J Ophthalmol 2017; 64:620-627. [PMID: 27853007 PMCID: PMC5151149 DOI: 10.4103/0301-4738.194328] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Primary cilia play a key role in sensory perception and various signaling pathways. Any defect in them leads to group of disorders called ciliopathies, and Bardet–Biedl syndrome (BBS, OMIM 209900) is one among them. The disorder is clinically and genetically heterogeneous, with various primary and secondary clinical manifestations, and shows autosomal recessive inheritance and highly prevalent in inbred/consanguineous populations. The disease mapped to at least twenty different genes (BBS1-BBS20), follow oligogenic inheritance pattern. BBS proteins localizes to the centerosome and regulates the biogenesis and functions of the cilia. In BBS, the functioning of various systemic organs (with ciliated cells) gets deranged and results in systemic manifestations. Certain components of the disease (such as obesity, diabetes, and renal problems) when noticed earlier offer a disease management benefit to the patients. However, the awareness of the disease is comparatively low and most often noticed only after severe vision loss in patients, which is usually in the first decade of the patient's age. In the current review, we have provided the recent updates retrieved from various types of scientific literature through journals, on the genetics, its molecular relevance, and the clinical outcome in BBS. The review in nutshell would provide the basic awareness of the disease that will have an impact in disease management and counseling benefits to the patients and their families.
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Affiliation(s)
- Sathya Priya
- SNONGC Department of Genetics and Molecular Biology, Kamal Nayan Institute for Research in Vision and Ophthalmology, Vision Research Foundation, Chennai, Tamil Nadu; School of Chemical and Biotechnology, SASTRA University, Thanjavur, Tamil Nadu, India
| | - Sheela Nampoothiri
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences and Research Center, Cochin, Kerala, India
| | - Parveen Sen
- Department of Vitreoretina Clinic, Medical Research Foundation, Chennai, Tamil Nadu, India
| | - S Sripriya
- SNONGC Department of Genetics and Molecular Biology, Kamal Nayan Institute for Research in Vision and Ophthalmology, Vision Research Foundation, Chennai, Tamil Nadu, India
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33
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Wanka H, Lutze P, Staar D, Peters B, Morch A, Vogel L, Chilukoti RK, Homuth G, Sczodrok J, Bäumgen I, Peters J. (Pro)renin receptor (ATP6AP2) depletion arrests As4.1 cells in the G0/G1 phase thereby increasing formation of primary cilia. J Cell Mol Med 2017; 21:1394-1410. [PMID: 28215051 PMCID: PMC5487920 DOI: 10.1111/jcmm.13069] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/24/2016] [Indexed: 01/07/2023] Open
Abstract
The (pro)renin receptor [(P)RR, ATP6AP2] is a multifunctional transmembrane protein that activates local renin-angiotensin systems, but also interacts with Wnt pathways and vacuolar H+ -ATPase (V-ATPase) during organogenesis. The aim of this study was to characterize the role of ATP6AP2 in the cell cycle in more detail. ATP6AP2 down-regulation by siRNA in renal As4.1 cells resulted in a reduction in the rate of proliferation and a G0/G1 phase cell cycle arrest. We identified a number of novel target genes downstream of ATP6AP2 knock-down that were related to the primary cilium (Bbs-1, Bbs-3, Bbs-7, Rabl5, Ttc26, Mks-11, Mks-5, Mks-2, Tctn2, Nme7) and the cell cycle (Pierce1, Clock, Ppif). Accordingly, the number of cells expressing the primary cilium was markedly increased. We found no indication that these effects were dependent of V-ATPase activity, as ATP6AP2 knock-down did not affect lysosomal pH and bafilomycin A neither influenced the ciliary expression pattern nor the percentage of ciliated cells. Furthermore, ATP6AP2 appears to be essential for mitosis. ATP6AP2 translocated from the endoplasmatic reticulum to mitotic spindle poles (pro-, meta- and anaphase) and the central spindle bundle (telophase) and ATP6AP2 knock-down results in markedly deformed spindles. We conclude that ATP6AP2 is necessary for cell division, cell cycle progression and mitosis. ATP6AP2 also inhibits ciliogenesis, thus promoting proliferation and preventing differentiation.
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Affiliation(s)
- Heike Wanka
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Philipp Lutze
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Doreen Staar
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Barbara Peters
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Anica Morch
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Lukas Vogel
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Ravi Kumar Chilukoti
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine and Ernst Moritz Arndt-University Greifswald, Greifswald, Germany
| | - Georg Homuth
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine and Ernst Moritz Arndt-University Greifswald, Greifswald, Germany
| | - Jaroslaw Sczodrok
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Inga Bäumgen
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
| | - Jörg Peters
- Department of Physiology, University Medicine Greifswald, Karlsburg, Germany
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34
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Liu X, Shen Q, Yu T, Huang H, Zhang Z, Ding J, Tang Y, Xu N, Yue S. Small GTPase Arl6 controls RH30 rhabdomyosarcoma cell growth through ciliogenesis and Hedgehog signaling. Cell Biosci 2016; 6:61. [PMID: 27999656 PMCID: PMC5154108 DOI: 10.1186/s13578-016-0126-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 11/28/2016] [Indexed: 12/04/2022] Open
Abstract
Background Rhabdomyosarcoma (RMS) originates from skeletal muscle precursors that fail to differentiate. Hedgehog (Hh) signaling and primary cilia contribute to the pathobiology of RMS. Results Here we showed ADP ribosylation factor like GTPase 6 (ARL6) localizes at the base of primary cilium, controls ciliogenesis and Hh signaling. The transcription of Arl6 is dynamic during the differentiation of myoblasts, companying with the growth and elimination of primary cilia. Arl6 expression is significantly up regulated in cilia-dependent RMS cells and tissues. Knockdown of Arl6 inhibits proliferation and promotes apoptosis of RMS RH30 cells through defected ciliogenesis and reduced Hh activity. Conclusions Taken together, the functions of Arl6 in ciliogenesis and Hh signaling suggest it as a potential RMS drug target. Electronic supplementary material The online version of this article (doi:10.1186/s13578-016-0126-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiaotong Liu
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
| | - Qiuhong Shen
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
| | - Tingting Yu
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
| | - Huijie Huang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
| | - Ziyu Zhang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
| | - Jie Ding
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
| | - Ying Tang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China.,Central Laboratory, The First People's Hospital of Wujiang District, Suzhou, 215200 People's Republic of China
| | - Ning Xu
- Department of Pathology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
| | - Shen Yue
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166 Jiangsu People's Republic of China
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35
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Abstract
Primary cilia are organelles that are present on many different cell types, either transiently or permanently. They play a crucial role in receiving signals from the environment and passing these signals to other parts of the cell. In that way, they are involved in diverse processes such as adipocyte differentiation and olfactory sensation. Mutations in genes coding for ciliary proteins often have pleiotropic effects and lead to clinical conditions, ciliopathies, with multiple symptoms. In this study, we reviewed observations from ciliopathies with obesity as one of the symptoms. It shows that variation in cilia-related genes is itself not a major cause of obesity in the population but may be a part of the multifactorial aetiology of this complex condition. Both common polymorphisms and rare deleterious variants may contribute to the obesity risk. Genotype-phenotype relationships have been noticed. Among the ciliary genes, obesity differs with regard to severity and age of onset, which may relate to the influence of each gene on the balance between pro- and anti-adipogenic processes. Analysis of the function and location of the proteins encoded by these ciliary genes suggests that obesity is more linked to activities at the basal area of the cilium, including initiation of the intraflagellar transport, but less to the intraflagellar transport itself. Regarding the role of cilia, three possible mechanistic processes underlying obesity are described: adipogenesis, neuronal food intake regulation and food odour perception.
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36
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Bhattacharyya S, Rainey MA, Arya P, Mohapatra BC, Mushtaq I, Dutta S, George M, Storck MD, McComb RD, Muirhead D, Todd GL, Gould K, Datta K, Gelineau-van Waes J, Band V, Band H. Endocytic recycling protein EHD1 regulates primary cilia morphogenesis and SHH signaling during neural tube development. Sci Rep 2016; 6:20727. [PMID: 26884322 PMCID: PMC4756679 DOI: 10.1038/srep20727] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 01/11/2016] [Indexed: 12/20/2022] Open
Abstract
Members of the four-member C-terminal EPS15-Homology Domain-containing (EHD) protein family play crucial roles in endocytic recycling of cell surface receptors from endosomes to the plasma membrane. In this study, we show that Ehd1 gene knockout in mice on a predominantly B6 background is embryonic lethal. Ehd1-null embryos die at mid-gestation with a failure to complete key developmental processes including neural tube closure, axial turning and patterning of the neural tube. We found that Ehd1-null embryos display short and stubby cilia on the developing neuroepithelium at embryonic day 9.5 (E9.5). Loss of EHD1 also deregulates the ciliary SHH signaling with Ehd1-null embryos displaying features indicative of increased SHH signaling, including a significant downregulation in the formation of the GLI3 repressor and increase in the ventral neuronal markers specified by SHH. Using Ehd1-null MEFS we found that EHD1 protein co-localizes with the SHH receptor Smoothened in the primary cilia upon ligand stimulation. Under the same conditions, EHD1 was shown to co-traffic with Smoothened into the developing primary cilia and we identify EHD1 as a direct binding partner of Smoothened. Overall, our studies identify the endocytic recycling regulator EHD1 as a novel regulator of the primary cilium-associated trafficking of Smoothened and Hedgehog signaling.
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Affiliation(s)
- Sohinee Bhattacharyya
- The Department of Pathology &Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.,Eppley Institute for Research in Cancer and Allied Diseases,University of Nebraska Medical Center, Omaha, NE, USA
| | - Mark A Rainey
- Eppley Institute for Research in Cancer and Allied Diseases,University of Nebraska Medical Center, Omaha, NE, USA
| | - Priyanka Arya
- The Department of Genetics, Cell Biology &Anatomy, University of Nebraska Medical Center, Omaha, NE, USA.,Eppley Institute for Research in Cancer and Allied Diseases,University of Nebraska Medical Center, Omaha, NE, USA
| | | | | | - Samikshan Dutta
- The Department of Biochemistry &Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Manju George
- Eppley Institute for Research in Cancer and Allied Diseases,University of Nebraska Medical Center, Omaha, NE, USA
| | - Matthew D Storck
- Eppley Institute for Research in Cancer and Allied Diseases,University of Nebraska Medical Center, Omaha, NE, USA
| | - Rodney D McComb
- The Department of Pathology &Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - David Muirhead
- The Department of Pathology &Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Gordon L Todd
- The Department of Genetics, Cell Biology &Anatomy, University of Nebraska Medical Center, Omaha, NE, USA
| | - Karen Gould
- The Department of Genetics, Cell Biology &Anatomy, University of Nebraska Medical Center, Omaha, NE, USA
| | - Kaustubh Datta
- The Department of Biochemistry &Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | | | - Vimla Band
- The Department of Genetics, Cell Biology &Anatomy, University of Nebraska Medical Center, Omaha, NE, USA.,Eppley Institute for Research in Cancer and Allied Diseases,University of Nebraska Medical Center, Omaha, NE, USA.,Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Hamid Band
- The Department of Pathology &Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.,The Department of Genetics, Cell Biology &Anatomy, University of Nebraska Medical Center, Omaha, NE, USA.,Eppley Institute for Research in Cancer and Allied Diseases,University of Nebraska Medical Center, Omaha, NE, USA.,Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
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Cellular Mechanisms of Ciliary Length Control. Cells 2016; 5:cells5010006. [PMID: 26840332 PMCID: PMC4810091 DOI: 10.3390/cells5010006] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 01/21/2016] [Accepted: 01/25/2016] [Indexed: 12/12/2022] Open
Abstract
Cilia and flagella are evolutionarily conserved, membrane-bound, microtubule-based organelles on the surface of most eukaryotic cells. They play important roles in coordinating a variety of signaling pathways during growth, development, cell mobility, and tissue homeostasis. Defects in ciliary structure or function are associated with multiple human disorders called ciliopathies. These diseases affect diverse tissues, including, but not limited to the eyes, kidneys, brain, and lungs. Many processes must be coordinated simultaneously in order to initiate ciliogenesis. These include cell cycle, vesicular trafficking, and axonemal extension. Centrioles play a central role in both cell cycle progression and ciliogenesis, making the transition between basal bodies and mitotic spindle organizers integral to both processes. The maturation of centrioles involves a functional shift from cell division toward cilium nucleation which takes place concurrently with its migration and fusion to the plasma membrane. Several proteinaceous structures of the distal appendages in mother centrioles are required for this docking process. Ciliary assembly and maintenance requires a precise balance between two indispensable processes; so called assembly and disassembly. The interplay between them determines the length of the resulting cilia. These processes require a highly conserved transport system to provide the necessary substances at the tips of the cilia and to recycle ciliary turnover products to the base using a based microtubule intraflagellar transport (IFT) system. In this review; we discuss the stages of ciliogenesis as well as mechanisms controlling the lengths of assembled cilia.
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The Function of Arf-like Proteins ARL2 and ARL3 in Photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:655-61. [PMID: 26427472 DOI: 10.1007/978-3-319-17121-0_87] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Arf-like proteins (ARLs) are ubiquitously expressed small G proteins of the RAS superfamily. In photoreceptors, ARL2 and ARL3 participate in the trafficking of lipidated membrane-associated proteins and colocalize in the inner segment with UNC119A and PDEδ. UNC119A and PDEδ are acyl- and prenyl-binding proteins, respectively, involved in trafficking of acylated (transducin-α subunit, nephrocystin NPHP3) and prenylated proteins (GRK1, PDE6). Germline Arl3 knockout mice do not survive beyond postnatal day 21 and display ciliary defects in multiple organs (kidney, liver and pancreas) as well as retinal degeneration. Conditional knockouts will be necessary to delineate mechanisms of protein transport in retina disease.
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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: 62] [Impact Index Per Article: 6.9] [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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Shoemark A, Dixon M, Beales PL, Hogg CL. Bardet Biedl syndrome: motile ciliary phenotype. Chest 2015; 147:764-770. [PMID: 25317630 DOI: 10.1378/chest.13-2913] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Cilia line the surface of the respiratory tract and beat in a coordinated wave to protect the lungs against infection. Bardet Biedl Syndrome (BBS) is a rare condition attributed to cilia dysfunction. Murine models of BBS suggest a respiratory phenotype; however, no reports have studied the translation of these findings in patients. METHODS We assessed the clinical symptoms of motile cilia dysfunction and the histology of ciliated respiratory epithelium in patients with BBS. RESULTS We report an increased prevalence of neonatal respiratory distress at birth (12%), general practitioner-diagnosed asthma (21%), otitis media (33%), and rhinitis (36%) in patients with BBS. These symptoms, however, occurred at a significantly reduced prevalence compared with patients with known motile cilia dysfunction (primary ciliary dyskinesia). Respiratory epithelial assessment revealed cellular damage, significant ciliary depletion (on 60% of ciliated cells), and goblet cell hyperplasia in patients with BBS (50% goblet cells). These findings were quantifiably similar to those of patients with asthma (P > .05). Surprisingly, motile cilia function and ultrastructure were grossly normal with the exception of occasional unique inclusions within the ciliary membrane. CONCLUSIONS In conclusion, motile ciliary structure and function are essentially normal in patients with BBS.
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Affiliation(s)
- Amelia Shoemark
- PCD Diagnostic Team, Royal Brompton and Harefield NHS Trust, National Heart and Lung Institute, Imperial College.
| | - Mellisa Dixon
- PCD Diagnostic Team, Royal Brompton and Harefield NHS Trust
| | - Philip L Beales
- Institute of Child Health, University College London, Great Ormond Street Hospital NHS Foundation Trust, London, England
| | - Claire L Hogg
- PCD Diagnostic Team, Royal Brompton and Harefield NHS Trust
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Barbelanne M, Hossain D, Chan DP, Peränen J, Tsang WY. Nephrocystin proteins NPHP5 and Cep290 regulate BBSome integrity, ciliary trafficking and cargo delivery. Hum Mol Genet 2014; 24:2185-200. [PMID: 25552655 DOI: 10.1093/hmg/ddu738] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Proper functioning of cilia, hair-like structures responsible for sensation and locomotion, requires nephrocystin-5 (NPHP5) and a multi-subunit complex called the Bardet-Biedl syndrome (BBS)ome, but their precise relationship is not understood. The BBSome is involved in the trafficking of membrane cargos to cilia. While it is known that a loss of any single subunit prevents ciliary trafficking of the BBSome and its cargos, the mechanisms underlying ciliary entry of this complex are not well characterized. Here, we report that a transition zone protein NPHP5 contains two separate BBS-binding sites and interacts with the BBSome to mediate its integrity. Depletion of NPHP5, or expression of NPHP5 mutant missing one binding site, specifically leads to dissociation of BBS2 and BBS5 from the BBSome and loss of ciliary BBS2 and BBS5 without compromising the ability of the other subunits to traffic into cilia. Depletion of Cep290, another transition zone protein that directly binds to NPHP5, causes additional dissociation of BBS8 and loss of ciliary BBS8. Furthermore, delivery of BBSome cargos, smoothened, VPAC2 and Rab8a, to the ciliary compartment is completely disabled in the absence of single BBS subunits, but is selectively impaired in the absence of NPHP5 or Cep290. These findings define a new role of NPHP5 and Cep290 in controlling integrity and ciliary trafficking of the BBSome, which in turn impinge on the delivery of ciliary cargo.
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Affiliation(s)
- Marine Barbelanne
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada, Faculté de Médecine, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Delowar Hossain
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada, Division of Experimental Medicine, McGill University, Montréal, QC H3A 1A3, Canada and
| | - David Puth Chan
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Johan Peränen
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
| | - William Y Tsang
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada, Faculté de Médecine, Université de Montréal, Montréal, QC H3C 3J7, Canada, Division of Experimental Medicine, McGill University, Montréal, QC H3A 1A3, Canada and
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Mourão A, Nager AR, Nachury MV, Lorentzen E. Structural basis for membrane targeting of the BBSome by ARL6. Nat Struct Mol Biol 2014; 21:1035-41. [PMID: 25402481 PMCID: PMC4255524 DOI: 10.1038/nsmb.2920] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/20/2014] [Indexed: 12/16/2022]
Abstract
The BBSome is a coat-like ciliary trafficking complex composed of proteins mutated in Bardet-Biedl syndrome (BBS). A critical step in BBSome-mediated sorting is recruitment of the BBSome to membranes by the GTP-bound Arf-like GTPase ARL6. We have determined crystal structures of Chlamydomonas reinhardtii ARL6-GDP, ARL6-GTP and the ARL6-GTP-BBS1 complex. The structures demonstrate how ARL6-GTP binds the BBS1 β-propeller at blades 1 and 7 and explain why GTP- but not GDP-bound ARL6 can recruit the BBSome to membranes. Single point mutations in the ARL6-GTP-BBS1 interface abolish the interaction of ARL6 with the BBSome and prevent the import of BBSomes into cilia. Furthermore, we show that BBS1 with the M390R mutation, responsible for 30% of all reported BBS disease cases, fails to interact with ARL6-GTP, thus providing a molecular rationale for patient pathologies.
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Affiliation(s)
- André Mourão
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Andrew R. Nager
- Department of Molecular and Cellular Physiology, Stanford University, School of Medicine, Stanford, CA 94305
| | - Maxence V. Nachury
- Department of Molecular and Cellular Physiology, Stanford University, School of Medicine, Stanford, CA 94305
| | - Esben Lorentzen
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
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Madhivanan K, Aguilar RC. Ciliopathies: the trafficking connection. Traffic 2014; 15:1031-56. [PMID: 25040720 DOI: 10.1111/tra.12195] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/28/2014] [Accepted: 07/08/2014] [Indexed: 12/15/2022]
Abstract
The primary cilium (PC) is a very dynamic hair-like membrane structure that assembles/disassembles in a cell-cycle-dependent manner and is present in almost every cell type. Despite being continuous with the plasma membrane, a diffusion barrier located at the ciliary base confers the PC properties of a separate organelle with very specific characteristics and membrane composition. Therefore, vesicle trafficking is the major process by which components are acquired for cilium formation and maintenance. In fact, a system of specific sorting signals controls the right of cargo admission into the cilia. Disruption to the ciliary structure or its function leads to multiorgan diseases known as ciliopathies. These illnesses arise from a spectrum of mutations in any of the more than 50 loci linked to these conditions. Therefore, it is not surprising that symptom variability (specific manifestations and severity) among and within ciliopathies appears to be an emerging characteristic. Nevertheless, one can speculate that mutations occurring in genes whose products contribute to the overall vesicle trafficking to the PC (i.e. affecting cilia assembly) will lead to more severe symptoms, whereas those involved in the transport of specific cargoes will result in milder phenotypes. In this review, we summarize the trafficking mechanisms to the cilia and also provide a description of the trafficking defects observed in some ciliopathies which can be correlated to the severity of the pathology.
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Mutation profile of BBS genes in Iranian patients with Bardet–Biedl syndrome: genetic characterization and report of nine novel mutations in five BBS genes. J Hum Genet 2014; 59:368-75. [DOI: 10.1038/jhg.2014.28] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 02/14/2014] [Accepted: 04/01/2014] [Indexed: 02/07/2023]
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Al-Hamed MH, van Lennep C, Hynes AM, Chrystal P, Eley L, Al-Fadhly F, El Sayed R, Simms RJ, Meyer B, Sayer JA. Functional modelling of a novel mutation in BBS5. Cilia 2014; 3:3. [PMID: 24559376 PMCID: PMC3931281 DOI: 10.1186/2046-2530-3-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 02/04/2014] [Indexed: 12/22/2022] Open
Abstract
Background Bardet-Biedl syndrome (BBS) is an autosomal recessive ciliopathy disorder with 18 known causative genes (BBS1-18). The primary clinical features are renal abnormalities, rod-cone dystrophy, post-axial polydactyly, learning difficulties, obesity and male hypogonadism. Results We describe the clinical phenotype in three Saudi siblings in whom we have identified a novel mutation in exon 12 of BBS5 (c.966dupT; p.Ala323CysfsX57). This single nucleotide duplication creates a frame shift results in a predicted elongated peptide. Translation blocking Morpholino oligonucleotides were used to create zebrafish bbs5 morphants. Morphants displayed retinal layering defects, abnormal cardiac looping and dilated, cystic pronephric ducts with reduced cilia expression. Morphants also displayed significantly reduced dextran clearance via the pronephros compared to wildtype embryos, suggesting reduced renal function in morphants. The eye, kidney and heart defects reported in morphant zebrafish resemble the human phenotype of BBS5 mutations. The pathogenicity of the novel BBS5 mutation was determined. Mutant mRNA was unable to rescue pleiotropic phenotypes of bbs5 morphant zebrafish and in cell culture we demonstrate a mislocalisation of mutant BBS5 protein which fails to localise discretely with the basal body. Conclusions We conclude that this novel BBS5 mutation has a deleterious function that accounts for the multisystem ciliopathy phenotype seen in affected human patients.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - John A Sayer
- International Centre for Life, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK.
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Sathya Priya C, Sen P, Umashankar V, Gupta N, Kabra M, Kumaramanickavel G, Stoetzel C, Dollfus H, Sripriya S. Mutation spectrum in BBS genes guided by homozygosity mapping in an Indian cohort. Clin Genet 2014; 87:161-6. [PMID: 24400638 DOI: 10.1111/cge.12342] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 01/06/2014] [Accepted: 01/06/2014] [Indexed: 11/29/2022]
Abstract
Bardet-Biedl syndrome (BBS), a ciliopathy disorder with pleiotropic effect manifests primarily as retinal degeneration along with renal insufficiency, polydactyly and obesity. In this study, we have performed homozygosity mapping using NspI 250K affymetrix gene chip followed by mutation screening of the candidate genes located in the homozygous blocks. These regions are prioritized based on the block length and candidature of the genes in BBS and other ciliopathies. Gene alterations in known BBS (22) and other ciliopathy genes such as ALMS1 (2) were seen in 24 of 30 families (80%). Mutations in BBS3 gene, inclusive of a novel recurrent mutation (p.I91T) accounted for 18% of the identified variations. Disease associated polymorphisms p.S70N (BBS2), rs1545 and rs1547 (BBS6) were also observed. This is the first study in Indian BBS patients and homozygosity mapping has proved to be an effective tool in prioritizing the candidate genes in consanguineous pedigrees. The study reveals a different mutation profile in the ciliopathy genes in Indian population and implication of novel loci/genes in 20% of the study group.
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Affiliation(s)
- C Sathya Priya
- SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, Tamilnadu, India; School of Chemical engineering and Biotechnology, SASTRA University, Thanjavur, Tamilnadu, India
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Abstract
The ARF-like (ARL) proteins, within the ARF family, are a collection of functionally diverse GTPases that share extensive (>40 %) identity with the ARFs and each other and are assumed to share basic mechanisms of regulation and a very incompletely documented degree of overlapping regulators. At least four ARLs were already present in the last eukaryotic common ancestor, along with one ARF, and these have been expanded to >20 members in mammals. We know little about the majority of these proteins so our review will focus on those about which the most is known, including ARL1, ARL2, ARL3, ARL4s, ARL6, ARL13s, and ARFRP1. From this fragmentary information we extract some generalizations and conclusions regarding the sources and extent of specificity and functions of the ARLs.
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Affiliation(s)
- Alfred Wittinghofer
- Max-Planck-Institute of Molecular Physiology, Dortmund, Nordrhein-Westfalen Germany
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Abstract
Cystic kidney diseases can cause end stage renal disease, affecting millions of individuals worldwide. They may arise early or later in life, are characterized by a spectrum of symptoms and can be caused by diverse genetic defects. The primary cilium, a microtubule-based organelle that can serve as a signaling antenna, has been demonstrated to have a significant role in ensuring correct kidney development and function. In the kidney, one of the signaling pathways that requires the cilium for normal development is Wnt signaling. In this review, the roles of primary cilia in relation to canonical and non-canonical Wnt/PCP signaling in cystic renal disease are described. The evidence of the associations between cilia, Wnt signaling and cystic renal disease is discussed and the significance of planar cell polarity-related mechanisms in cystic kidney disease is presented. Although defective Wnt signaling is not the only cause of renal disease, research is increasingly highlighting its importance, encouraging the development of Wnt-associated diagnostic and prognostic tools for cystic renal disease.
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Wang J, Deretic D. Molecular complexes that direct rhodopsin transport to primary cilia. Prog Retin Eye Res 2013; 38:1-19. [PMID: 24135424 DOI: 10.1016/j.preteyeres.2013.08.004] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/13/2013] [Accepted: 08/19/2013] [Indexed: 11/27/2022]
Abstract
Rhodopsin is a key molecular constituent of photoreceptor cells, yet understanding of how it regulates photoreceptor membrane trafficking and biogenesis of light-sensing organelles, the rod outer segments (ROS) is only beginning to emerge. Recently identified sequence of well-orchestrated molecular interactions of rhodopsin with the functional networks of Arf and Rab GTPases at multiple stages of intracellular targeting fits well into the complex framework of the biogenesis and maintenance of primary cilia, of which the ROS is one example. This review will discuss the latest progress in dissecting the molecular complexes that coordinate rhodopsin incorporation into ciliary-targeted carriers with the recruitment and activation of membrane tethering complexes and regulators of fusion with the periciliary plasma membrane. In addition to revealing the fundamental principals of ciliary membrane renewal, recent advances also provide molecular insight into the ways by which disruptions of the exquisitely orchestrated interactions lead to cilia dysfunction and result in human retinal dystrophies and syndromic diseases that affect multiple organs, including the eyes.
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Affiliation(s)
- Jing Wang
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Dusanka Deretic
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, NM 87131, USA; Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM 87131, USA.
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Zhang Q, Hu J, Ling K. Molecular views of Arf-like small GTPases in cilia and ciliopathies. Exp Cell Res 2013; 319:2316-22. [PMID: 23548655 PMCID: PMC3742637 DOI: 10.1016/j.yexcr.2013.03.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 03/19/2013] [Indexed: 11/28/2022]
Abstract
The primary cilia are microtubule-based organelles that protrude from most of the eukaryotic cells. Recognized as the cell's antenna, primary cilium functions as a signaling hub for many physiologically and developmentally important signaling cascades. Ciliary dysfunction causes a wide spectrum of syndromic human genetic diseases collectively termed "ciliopathies". Mounting evidences have shown that various small GTPases have been implicated in the context of cilia as well as human ciliopathies. However, how these small GTPases affect cilia formation and function remains poorly understood. Here we review and discuss the ciliary role of three Arf-like small GTPases (Arls), Arl3, Arl6, and Arl13b.
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Affiliation(s)
- Qing Zhang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- Department of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Jinghua Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- NIH Mayo Translational PKD Center
- Department of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Kun Ling
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- NIH Mayo Translational PKD Center
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