251
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Conduit SE, Dyson JM, Mitchell CA. Inositol polyphosphate 5-phosphatases; new players in the regulation of cilia and ciliopathies. FEBS Lett 2012; 586:2846-57. [PMID: 22828281 DOI: 10.1016/j.febslet.2012.07.037] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 07/16/2012] [Accepted: 07/16/2012] [Indexed: 10/28/2022]
Abstract
Phosphoinositides regulate numerous cellular events via the recruitment and activation of multiple lipid-binding effector proteins. The precise temporal and spatial regulation of phosphoinositide signals by the co-ordinated activities of phosphoinositide kinases and phosphatases is essential for homeostasis and development. Mutations in two inositol polyphosphate 5-phosphatases, INPP5E and OCRL, cause the cerebrorenal syndromes of Joubert and Lowe's, respectively. INPP5E and OCRL exhibit overlapping phosphoinositide substrate specificity and subcellular localisation, including an association with the primary cilia. Here, we review recent studies that identify a new role for these enzymes in the regulation of primary cilia function. Joubert syndrome has been extensively linked to primary cilia defects, and Lowe's may represent a new class of 'ciliopathy associated' syndromes.
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Affiliation(s)
- Sarah E Conduit
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
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252
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Pan J, Seeger-Nukpezah T, Golemis EA. The role of the cilium in normal and abnormal cell cycles: emphasis on renal cystic pathologies. Cell Mol Life Sci 2012; 70:1849-74. [PMID: 22782110 DOI: 10.1007/s00018-012-1052-z] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 05/08/2012] [Accepted: 06/05/2012] [Indexed: 12/28/2022]
Abstract
The primary cilium protrudes from the cell surface and acts as a sensor for chemical and mechanical growth cues, with receptors for a number of growth factors (PDGFα, Hedgehog, Wnt, Notch) concentrated within the ciliary membrane. In normal tissues, the cilium assembles after cells exit mitosis and is resorbed as part of cell cycle re-entry. Although regulation of the cilium by cell cycle transitions has been appreciated for over 100 years, only recently have data emerged to indicate the cilium also exerts influence on the cell cycle. The resorption/protrusion cycle, regulated by proteins including Aurora-A, VHL, and GSK-3β, influences cell responsiveness to growth cues involving cilia-linked receptors; further, resorption liberates the ciliary basal body to differentiate into the centrosome, which performs discrete functions in S-, G2-, and M-phase. Besides these roles, the cilium provides a positional cue that regulates polarity of cell division, and thus directs cells towards fates of differentiation versus proliferation. In this review, we summarize the specific mechanisms mediating the cilia-cell cycle dialog. We then emphasize the examples of polycystic kidney disease (PKD), nephronopthisis (NPHP), and VHL-linked renal cysts as cases in which defects of ciliary function influence disease pathology, and may also condition response to treatment.
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Affiliation(s)
- Junmin Pan
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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253
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Vogel TW, Dlouhy BJ, Menezes AH. Craniovertebral junction abnormality in a case of Joubert syndrome. Childs Nerv Syst 2012; 28:1109-12. [PMID: 22231569 DOI: 10.1007/s00381-012-1682-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Accepted: 01/02/2012] [Indexed: 10/14/2022]
Affiliation(s)
- Timothy W Vogel
- Department of Neurosurgery, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA.
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254
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Davis EE, Katsanis N. The ciliopathies: a transitional model into systems biology of human genetic disease. Curr Opin Genet Dev 2012; 22:290-303. [PMID: 22632799 DOI: 10.1016/j.gde.2012.04.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 04/24/2012] [Accepted: 04/24/2012] [Indexed: 01/19/2023]
Abstract
The last decade has witnessed an explosion in the identification of genes, mutations in which appear sufficient to cause clinical phenotypes in humans. This is especially true for disorders of ciliary dysfunction in which an excess of 50 causal loci are now known; this discovery was driven partly by an improved understanding of the protein composition of the cilium and the co-occurrence of clinical phenotypes associated with ciliary dysfunction. Despite this progress, the fundamental challenge of predicting phenotype and or clinical progression based on single locus information remains unsolved. Here, we explore how the combinatorial knowledge of allele quality and quantity, an improved understanding of the biological composition of the primary cilium, and the expanded appreciation of the subcellular roles of this organelle can be synthesized to generate improved models that can explain both causality but also variable penetrance and expressivity.
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Affiliation(s)
- Erica E Davis
- Center for Human Disease Modeling, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
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255
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Luo N, West CC, Murga-Zamalloa CA, Sun L, Anderson RM, Wells CD, Weinreb RN, Travers JB, Khanna H, Sun Y. OCRL localizes to the primary cilium: a new role for cilia in Lowe syndrome. Hum Mol Genet 2012; 21:3333-44. [PMID: 22543976 PMCID: PMC3392109 DOI: 10.1093/hmg/dds163] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Oculocerebral renal syndrome of Lowe (OCRL or Lowe syndrome), a severe X-linked congenital disorder characterized by congenital cataracts and glaucoma, mental retardation and kidney dysfunction, is caused by mutations in the OCRL gene. OCRL is a phosphoinositide 5-phosphatase that interacts with small GTPases and is involved in intracellular trafficking. Despite extensive studies, it is unclear how OCRL mutations result in a myriad of phenotypes found in Lowe syndrome. Our results show that OCRL localizes to the primary cilium of retinal pigment epithelial cells, fibroblasts and kidney tubular cells. Lowe syndrome-associated mutations in OCRL result in shortened cilia and this phenotype can be rescued by the introduction of wild-type OCRL; in vivo, knockdown of ocrl in zebrafish embryos results in defective cilia formation in Kupffer vesicles and cilia-dependent phenotypes. Cumulatively, our data provide evidence for a role of OCRL in cilia maintenance and suggest the involvement of ciliary dysfunction in the manifestation of Lowe syndrome.
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Affiliation(s)
- Na Luo
- Department of Ophthalmology, Glick Eye Institute, Indiana University, 1601 W Michigan St., Indianapolis, IN 46202, USA
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256
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Srour M, Schwartzentruber J, Hamdan FF, Ospina LH, Patry L, Labuda D, Massicotte C, Dobrzeniecka S, Capo-Chichi JM, Papillon-Cavanagh S, Samuels ME, Boycott KM, Shevell MI, Laframboise R, Désilets V, Maranda B, Rouleau GA, Majewski J, Michaud JL. Mutations in C5ORF42 cause Joubert syndrome in the French Canadian population. Am J Hum Genet 2012; 90:693-700. [PMID: 22425360 DOI: 10.1016/j.ajhg.2012.02.011] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 01/23/2012] [Accepted: 02/13/2012] [Indexed: 11/29/2022] Open
Abstract
Joubert syndrome (JBTS) is an autosomal-recessive disorder characterized by a distinctive mid-hindbrain malformation, developmental delay with hypotonia, ocular-motor apraxia, and breathing abnormalities. Although JBTS was first described more than 40 years ago in French Canadian siblings, the causal mutations have not yet been identified in this family nor in most French Canadian individuals subsequently described. We ascertained a cluster of 16 JBTS-affected individuals from 11 families living in the Lower St. Lawrence region. SNP genotyping excluded the presence of a common homozygous mutation that would explain the clustering of these individuals. Exome sequencing performed on 15 subjects showed that nine affected individuals from seven families (including the original JBTS family) carried rare compound-heterozygous mutations in C5ORF42. Two missense variants (c.4006C>T [p.Arg1336Trp] and c.4690G>A [p.Ala1564Thr]) and a splicing mutation (c.7400+1G>A), which causes exon skipping, were found in multiple subjects that were not known to be related, whereas three other truncating mutations (c.6407del [p.Pro2136Hisfs*31], c.4804C>T [p.Arg1602*], and c.7477C>T [p.Arg2493*]) were identified in single individuals. None of the unaffected first-degree relatives were compound heterozygous for these mutations. Moreover, none of the six putative mutations were detected among 477 French Canadian controls. Our data suggest that mutations in C5ORF42 explain a large portion of French Canadian individuals with JBTS.
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Affiliation(s)
- Myriam Srour
- Centre of Excellence in Neurosciences, Université de Montréal and Sainte-Justine Hospital Research Center, Montréal, QC, Canada
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257
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Czarnecki PG, Shah JV. The ciliary transition zone: from morphology and molecules to medicine. Trends Cell Biol 2012; 22:201-10. [PMID: 22401885 DOI: 10.1016/j.tcb.2012.02.001] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 01/28/2012] [Accepted: 02/01/2012] [Indexed: 11/29/2022]
Abstract
Researchers from various disciplines, including cell and developmental biology, genetics and molecular medicine, have revealed an exceptional diversity of cellular functions that are mediated by cilia-dependent mechanisms. Recent studies have directed our attention to proteins that localize to the ciliary transition zone (TZ), a small evolutionarily conserved subcompartment that is situated between the basal body (BB) and the more distal ciliary axoneme. These reports shed light on the roles of TZ proteins in ciliogenesis, ciliary protein homeostasis and specification of ciliary signaling, and pave the way for understanding their contribution to human ciliopathies. In this review, we describe the interplay of multimeric protein complexes at the TZ, integrating morphological, genetic and proteomic data towards an account of TZ function in ciliary physiology.
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Affiliation(s)
- Peter G Czarnecki
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
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258
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Simms RJ, Hynes AM, Eley L, Inglis D, Chaudhry B, Dawe HR, Sayer JA. Modelling a ciliopathy: Ahi1 knockdown in model systems reveals an essential role in brain, retinal, and renal development. Cell Mol Life Sci 2012; 69:993-1009. [PMID: 21959375 PMCID: PMC11115044 DOI: 10.1007/s00018-011-0826-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 09/09/2011] [Accepted: 09/12/2011] [Indexed: 02/03/2023]
Abstract
Joubert syndrome and related diseases (JSRD) are cerebello-oculo-renal syndromes with phenotypes including cerebellar hypoplasia, retinal dystrophy, and nephronophthisis (a cystic kidney disease). Mutations in AHI1 are the most common genetic cause of JSRD, with developmental hindbrain anomalies and retinal degeneration being prominent features. We demonstrate that Ahi1, a WD40 domain-containing protein, is highly conserved throughout evolution and its expression associates with ciliated organisms. In zebrafish ahi1 morphants, the phenotypic spectrum of JSRD is modeled, with embryos showing brain, eye, and ear abnormalities, together with renal cysts and cloacal dilatation. Following ahi1 knockdown in zebrafish, we demonstrate loss of cilia at Kupffer's vesicle and subsequently defects in cardiac left-right asymmetry. Finally, using siRNA in renal epithelial cells we demonstrate a role for Ahi1 in both ciliogenesis and cell-cell junction formation. These data support a role for Ahi1 in epithelial cell organization and ciliary formation and explain the ciliopathy phenotype of AHI1 mutations in man.
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Affiliation(s)
- Roslyn J. Simms
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ UK
| | - Ann Marie Hynes
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ UK
| | - Lorraine Eley
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ UK
| | - David Inglis
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE UK
| | - Bill Chaudhry
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ UK
| | - Helen R. Dawe
- Biosciences: College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter, EX4 4QD UK
| | - John A. Sayer
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ UK
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259
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Pirruccello M, De Camilli P. Inositol 5-phosphatases: insights from the Lowe syndrome protein OCRL. Trends Biochem Sci 2012; 37:134-43. [PMID: 22381590 DOI: 10.1016/j.tibs.2012.01.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 01/13/2012] [Accepted: 01/24/2012] [Indexed: 12/01/2022]
Abstract
The precise regulation of phosphoinositide lipids in cellular membranes is crucial for cellular survival and function. Inositol 5-phosphatases have been implicated in a variety of disorders, including various cancers, obesity, type 2 diabetes, neurodegenerative diseases and rare genetic conditions. Despite the obvious impact on human health, relatively little structural and biochemical information is available for this family. Here, we review recent structural and mechanistic work on the 5-phosphatases with a focus on OCRL, whose loss of function results in oculocerebrorenal syndrome of Lowe and Dent 2 disease. Studies of OCRL emphasize how the actions of 5-phosphatases rely on both intrinsic and extrinsic membrane recognition properties for full catalytic function. Additionally, structural analysis of missense mutations in the catalytic domain of OCRL provides insight into the phenotypic heterogeneity observed in Lowe syndrome and Dent disease.
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Affiliation(s)
- Michelle Pirruccello
- Department of Cell Biology, HHMI and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
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260
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Abstract
Over the past two decades, our understanding of phospoinositide 3-kinases (PI3Ks) has progressed from the identification of an enzymatic activity associated with growth factors, GPCRs and certain oncogene products to a disease target in cancer and inflammation, with PI3K inhibitors currently in clinical trials. Elucidation of PI3K-dependent networks led to the discovery of the phosphoinositide-binding PH, PX and FYVE domains as conduits of intracellular lipid signalling, the determination of the molecular function of the tumour suppressor PTEN and the identification of AKT and mTOR protein kinases as key regulators of cell growth. Here we look back at the main discoveries that shaped the PI3K field.
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261
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Proteomic analysis of mammalian primary cilia. Curr Biol 2012; 22:414-9. [PMID: 22326026 DOI: 10.1016/j.cub.2012.01.031] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 12/16/2011] [Accepted: 01/16/2012] [Indexed: 11/23/2022]
Abstract
The primary cilium is a microtubule-based organelle that senses extracellular signals as a cellular antenna. Primary cilia are found on many types of cells in our body and play important roles in development and physiology. Defects of primary cilia cause a broad class of human genetic diseases called ciliopathies. To gain new insights into ciliary functions and better understand the molecular mechanisms underlying ciliopathies, it is of high importance to generate a catalog of primary cilia proteins. In this study, we isolated primary cilia from mouse kidney cells by using a calcium-shock method and identified 195 candidate primary cilia proteins by MudPIT (multidimensional protein identification technology), protein correlation profiling, and subtractive proteomic analysis. Based on comparisons with other proteomic studies of cilia, around 75% of our candidate primary cilia proteins are shared components with motile or specialized sensory cilia. The remaining 25% of the candidate proteins are possible primary cilia-specific proteins. These possible primary cilia-specific proteins include EVC2, INPP5E, and inversin, several of which have been linked to known ciliopathies. We have performed the first reported proteomic analysis of primary cilia from mammalian cells. These results provide new insights into primary cilia structure and function.
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262
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Poretti A, Vitiello G, Hennekam RCM, Arrigoni F, Bertini E, Borgatti R, Brancati F, D'Arrigo S, Faravelli F, Giordano L, Huisman TAGM, Iannicelli M, Kluger G, Kyllerman M, Landgren M, Lees MM, Pinelli L, Romaniello R, Scheer I, Schwarz CE, Spiegel R, Tibussek D, Valente EM, Boltshauser E. Delineation and diagnostic criteria of Oral-Facial-Digital Syndrome type VI. Orphanet J Rare Dis 2012; 7:4. [PMID: 22236771 PMCID: PMC3313869 DOI: 10.1186/1750-1172-7-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 01/11/2012] [Indexed: 01/20/2023] Open
Abstract
Oral-Facial-Digital Syndrome type VI (OFD VI) represents a rare phenotypic subtype of Joubert syndrome and related disorders (JSRD). In the original report polydactyly, oral findings, intellectual disability, and absence of the cerebellar vermis at post-mortem characterized the syndrome. Subsequently, the molar tooth sign (MTS) has been found in patients with OFD VI, prompting the inclusion of OFD VI in JSRD. We studied the clinical, neurodevelopmental, neuroimaging, and genetic findings in a cohort of 16 patients with OFD VI. We derived the following inclusion criteria from the literature: 1) MTS and one oral finding and polydactyly, or 2) MTS and more than one typical oral finding. The OFD VI neuroimaging pattern was found to be more severe than in other JSRD subgroups and includes severe hypoplasia of the cerebellar vermis, hypoplastic and dysplastic cerebellar hemispheres, marked enlargement of the posterior fossa, increased retrocerebellar collection of cerebrospinal fluid, abnormal brainstem, and frequently supratentorial abnormalities that occasionally include characteristic hypothalamic hamartomas. Additionally, two new JSRD neuroimaging findings (ascending superior cerebellar peduncles and fused thalami) have been identified. Tongue hamartomas, additional frenula, upper lip notch, and mesoaxial polydactyly are specific findings in OFD VI, while cleft lip/palate and other types of polydactyly of hands and feet are not specific. Involvement of other organs may include ocular findings, particularly colobomas. The majority of the patients have absent motor development and profound cognitive impairment. In OFD VI, normal cognitive functions are possible, but exceptional. Sequencing of known JSRD genes in most patients failed to detect pathogenetic mutations, therefore the genetic basis of OFD VI remains unknown. Compared with other JSRD subgroups, the neurological findings and impairment of motor development and cognitive functions in OFD VI are significantly worse, suggesting a correlation with the more severe neuroimaging findings. Based on the literature and this study we suggest as diagnostic criteria for OFD VI: MTS and one or more of the following: 1) tongue hamartoma(s) and/or additional frenula and/or upper lip notch; 2) mesoaxial polydactyly of one or more hands or feet; 3) hypothalamic hamartoma.
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Affiliation(s)
- Andrea Poretti
- Department of Pediatric Neurology, University Children's Hospital of Zurich, Switzerland
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263
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Coon BG, Hernandez V, Madhivanan K, Mukherjee D, Hanna CB, Barinaga-Rementeria Ramirez I, Lowe M, Beales PL, Aguilar RC. The Lowe syndrome protein OCRL1 is involved in primary cilia assembly. Hum Mol Genet 2012; 21:1835-47. [DOI: 10.1093/hmg/ddr615] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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264
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Dyson JM, Fedele CG, Davies EM, Becanovic J, Mitchell CA. Phosphoinositide phosphatases: just as important as the kinases. Subcell Biochem 2012; 58:215-279. [PMID: 22403078 DOI: 10.1007/978-94-007-3012-0_7] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Phosphoinositide phosphatases comprise several large enzyme families with over 35 mammalian enzymes identified to date that degrade many phosphoinositide signals. Growth factor or insulin stimulation activates the phosphoinositide 3-kinase that phosphorylates phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P(2)] to form phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)], which is rapidly dephosphorylated either by PTEN (phosphatase and tensin homologue deleted on chromosome 10) to PtdIns(4,5)P(2), or by the 5-phosphatases (inositol polyphosphate 5-phosphatases), generating PtdIns(3,4)P(2). 5-phosphatases also hydrolyze PtdIns(4,5)P(2) forming PtdIns(4)P. Ten mammalian 5-phosphatases have been identified, which regulate hematopoietic cell proliferation, synaptic vesicle recycling, insulin signaling, and embryonic development. Two 5-phosphatase genes, OCRL and INPP5E are mutated in Lowe and Joubert syndrome respectively. SHIP [SH2 (Src homology 2)-domain inositol phosphatase] 2, and SKIP (skeletal muscle- and kidney-enriched inositol phosphatase) negatively regulate insulin signaling and glucose homeostasis. SHIP2 polymorphisms are associated with a predisposition to insulin resistance. SHIP1 controls hematopoietic cell proliferation and is mutated in some leukemias. The inositol polyphosphate 4-phosphatases, INPP4A and INPP4B degrade PtdIns(3,4)P(2) to PtdIns(3)P and regulate neuroexcitatory cell death, or act as a tumor suppressor in breast cancer respectively. The Sac phosphatases degrade multiple phosphoinositides, such as PtdIns(3)P, PtdIns(4)P, PtdIns(5)P and PtdIns(3,5)P(2) to form PtdIns. Mutation in the Sac phosphatase gene, FIG4, leads to a degenerative neuropathy. Therefore the phosphatases, like the lipid kinases, play major roles in regulating cellular functions and their mutation or altered expression leads to many human diseases.
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Affiliation(s)
- Jennifer M Dyson
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, 3800, Clayton, Australia
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265
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Abstract
The Golgi complex is a ribbon-like organelle composed of stacks of flat cisternae interconnected by tubular junctions. It occupies a central position in the endomembrane system as proteins and lipids that are synthesized in the endoplasmic reticulum (ER) pass through the Golgi complex to undergo biosynthetic modification (mainly glycosylation) and to be sorted to their final destinations. In addition the Golgi complex possesses a number of activities, apparently not directly connected with its main role in trafficking and sorting, which have been recently reviewed in Wilson et al. 2011. In spite of the constant massive flux of material the Golgi complex maintains its identity and phosphoinositides (PIs), among other factors, play a central role in this process. The active metabolism of PIs at the Golgi is necessary for the proper functioning of the organelle both in terms of membrane trafficking/sorting and its manifold metabolic and signalling activities. Phosphatidylinositol 4-phosphate (PtdIns4P), in particular, is responsible for the recruitment of numerous cytosolic proteins that recognise and bind PtdIns4P via specific lipid-binding domains. In this chapter we will summarize the findings that have contributed to our current understanding of the role of PIs in the biology of the Golgi complex in terms of the regulation of PI metabolism and the functional roles and regulation of PtdIns4P effectors.
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Affiliation(s)
- Giovanni D'Angelo
- Telethon Institute of Genetics and Medicine, Via Pietro Castellino, 111, 80131, Napoli, Italy,
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266
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Abstract
Phosphoinositides (PIs) are minor components of cellular membranes that play critical regulatory roles in several intracellular functions. This chapter describes the main enzymes regulating the turnover of each of the seven PIs in mammalian cells and introduces to some of their intracellular functions and to some evidences of their involvement in human diseases. Due to the complex interrelation between the distinct PIs and the plethora of functions that they can regulate inside a cell, this chapter is not meant to be a comprehensive coverage of all aspects of PI signalling but rather an introduction to this complex signalling field. For more details of their regulation/functions and extensive description of their intracellular roles, more detailed reviews are suggested on each single topic.
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Affiliation(s)
- Tania Maffucci
- Centre for Diabetes, Blizard Institute, Inositide Signalling Group, Queen Mary University of London, Barts and The London School of Medicine and Dentistry, UK.
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267
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Leslie NR, Dixon MJ, Schenning M, Gray A, Batty IH. Distinct inactivation of PI3K signalling by PTEN and 5-phosphatases. Adv Biol Regul 2012; 52:205-213. [PMID: 21930147 DOI: 10.1016/j.advenzreg.2011.09.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 09/06/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Nick R Leslie
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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268
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Christensen ST, Clement CA, Satir P, Pedersen LB. Primary cilia and coordination of receptor tyrosine kinase (RTK) signalling. J Pathol 2012; 226:172-84. [PMID: 21956154 PMCID: PMC4294548 DOI: 10.1002/path.3004] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 09/20/2011] [Accepted: 09/22/2011] [Indexed: 12/14/2022]
Abstract
Primary cilia are microtubule-based sensory organelles that coordinate signalling pathways in cell-cycle control, migration, differentiation and other cellular processes critical during development and for tissue homeostasis. Accordingly, defects in assembly or function of primary cilia lead to a plethora of developmental disorders and pathological conditions now known as ciliopathies. In this review, we summarize the current status of the role of primary cilia in coordinating receptor tyrosine kinase (RTK) signalling pathways. Further, we present potential mechanisms of signalling crosstalk and networking in the primary cilium and discuss how defects in ciliary RTK signalling are linked to human diseases and disorders.
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269
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Huang L, Szymanska K, Jensen V, Janecke A, Innes A, Davis E, Frosk P, Li C, Willer J, Chodirker B, Greenberg C, McLeod D, Bernier F, Chudley A, Müller T, Shboul M, Logan C, Loucks C, Beaulieu C, Bowie R, Bell S, Adkins J, Zuniga F, Ross K, Wang J, Ban M, Becker C, Nürnberg P, Douglas S, Craft C, Akimenko MA, Hegele R, Ober C, Utermann G, Bolz H, Bulman D, Katsanis N, Blacque O, Doherty D, Parboosingh J, Leroux M, Johnson C, Boycott K. TMEM237 is mutated in individuals with a Joubert syndrome related disorder and expands the role of the TMEM family at the ciliary transition zone. Am J Hum Genet 2011; 89:713-30. [PMID: 22152675 PMCID: PMC3234373 DOI: 10.1016/j.ajhg.2011.11.005] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/25/2011] [Accepted: 11/08/2011] [Indexed: 12/23/2022] Open
Abstract
Joubert syndrome related disorders (JSRDs) have broad but variable phenotypic overlap with other ciliopathies. The molecular etiology of this overlap is unclear but probably arises from disrupting common functional module components within primary cilia. To identify additional module elements associated with JSRDs, we performed homozygosity mapping followed by next-generation sequencing (NGS) and uncovered mutations in TMEM237 (previously known as ALS2CR4). We show that loss of the mammalian TMEM237, which localizes to the ciliary transition zone (TZ), results in defective ciliogenesis and deregulation of Wnt signaling. Furthermore, disruption of Danio rerio (zebrafish) tmem237 expression produces gastrulation defects consistent with ciliary dysfunction, and Caenorhabditis elegans jbts-14 genetically interacts with nphp-4, encoding another TZ protein, to control basal body-TZ anchoring to the membrane and ciliogenesis. Both mammalian and C. elegans TMEM237/JBTS-14 require RPGRIP1L/MKS5 for proper TZ localization, and we demonstrate additional functional interactions between C. elegans JBTS-14 and MKS-2/TMEM216, MKSR-1/B9D1, and MKSR-2/B9D2. Collectively, our findings integrate TMEM237/JBTS-14 in a complex interaction network of TZ-associated proteins and reveal a growing contribution of a TZ functional module to the spectrum of ciliopathy phenotypes.
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Affiliation(s)
- Lijia Huang
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - Katarzyna Szymanska
- Section of Ophthalmology and Neurosciences, Leeds Institute of Molecular Medicine, St. James's University Hospital, Leeds LS9 7TF, UK
| | - Victor L. Jensen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Andreas R. Janecke
- Department of Pediatrics II, Innsbruck Medical University, Innsbruck 6020, Austria
- Division of Human Genetics, Innsbruck Medical University, Innsbruck 6020, Austria
| | - A. Micheil Innes
- Department of Medical Genetics, University of Calgary, Calgary, AB T3B 6A8, Canada
| | - Erica E. Davis
- Center for Human Disease Modeling, Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Patrick Frosk
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3R 0J9, Canada
| | - Chunmei Li
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Jason R. Willer
- Center for Human Disease Modeling, Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Bernard N. Chodirker
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3R 0J9, Canada
| | - Cheryl R. Greenberg
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3R 0J9, Canada
| | - D. Ross McLeod
- Department of Medical Genetics, University of Calgary, Calgary, AB T3B 6A8, Canada
| | - Francois P. Bernier
- Department of Medical Genetics, University of Calgary, Calgary, AB T3B 6A8, Canada
| | - Albert E. Chudley
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3R 0J9, Canada
| | - Thomas Müller
- Department of Pediatrics II, Innsbruck Medical University, Innsbruck 6020, Austria
| | - Mohammad Shboul
- Institute of Medical Biology: Human Embryology, 8A Biomedical Grove, #05-40 Immunos, Singapore 138648, Singapore
| | - Clare V. Logan
- Section of Ophthalmology and Neurosciences, Leeds Institute of Molecular Medicine, St. James's University Hospital, Leeds LS9 7TF, UK
| | - Catrina M. Loucks
- Department of Medical Genetics, University of Calgary, Calgary, AB T3B 6A8, Canada
| | - Chandree L. Beaulieu
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - Rachel V. Bowie
- School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Sandra M. Bell
- Section of Ophthalmology and Neurosciences, Leeds Institute of Molecular Medicine, St. James's University Hospital, Leeds LS9 7TF, UK
| | - Jonathan Adkins
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Freddi I. Zuniga
- Mary D. Allen Laboratory in Vision Research, Doheny Eye Institute, Departments of Ophthalmology and Cell and Neurobiology, Los Angeles, CA 90033-9224, USA
| | - Kevin D. Ross
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Jian Wang
- Robarts Research Institute and University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Matthew R. Ban
- Robarts Research Institute and University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Christian Becker
- Cologne Center for Genomics, University of Cologne, 50931 Cologne, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics, University of Cologne, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Stuart Douglas
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - Cheryl M. Craft
- Mary D. Allen Laboratory in Vision Research, Doheny Eye Institute, Departments of Ophthalmology and Cell and Neurobiology, Los Angeles, CA 90033-9224, USA
| | | | - Robert A. Hegele
- Robarts Research Institute and University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Carole Ober
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Gerd Utermann
- Division of Human Genetics, Innsbruck Medical University, Innsbruck 6020, Austria
| | - Hanno J. Bolz
- Center for Human Genetics, Bioscientia, 55218 Ingelheim, Germany
- Institute of Human Genetics, University Hospital of Cologne, 50931 Cologne, Germany
| | - Dennis E. Bulman
- Ottawa Hospital Research Institute and University of Ottawa, Ottawa, ON K1H 8L6, Canada
| | - Nicholas Katsanis
- Center for Human Disease Modeling, Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Oliver E. Blacque
- School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Dan Doherty
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | | | - Michel R. Leroux
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Colin A. Johnson
- Section of Ophthalmology and Neurosciences, Leeds Institute of Molecular Medicine, St. James's University Hospital, Leeds LS9 7TF, UK
| | - Kym M. Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
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270
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Zaki MS, Sattar S, Massoudi RA, Gleeson JG. Co-occurrence of distinct ciliopathy diseases in single families suggests genetic modifiers. Am J Med Genet A 2011; 155A:3042-9. [PMID: 22002901 PMCID: PMC3415794 DOI: 10.1002/ajmg.a.34173] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 05/29/2011] [Indexed: 01/06/2023]
Abstract
Disorders within the “ciliopathy” spectrum include Joubert (JS), Bardet–Biedl syndromes (BBS), and nephronophthisis (NPHP). Although mutations in single ciliopathy genes can lead to these different syndromes between families, there have been no reports of phenotypic discordance within a single family. We report on two consanguineous families with discordant ciliopathies in sibling. In Ciliopathy-672, the older child displayed dialysis-dependent NPHP whereas the younger displayed the pathognomonic molar tooth MRI sign (MTS) of JS. A second branch displayed two additional children with NPHP. In Ciliopathy-1491, the oldest child displayed classical features of BBS whereas the two younger children displayed the MTS. Importantly, the children with BBS and NPHP lacked MTS, whereas children with JS lacked obesity or NPHP, and the child with BBS lacked MTS and NPHP. Features common to all three disorders included intellectual disability, postaxial polydactyly, and visual reduction. The variable phenotypic expressivity in this family suggests that genetic modifiers may determine specific clinical features within the ciliopathy spectrum. © 2011 Wiley Periodicals, Inc.
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Affiliation(s)
- Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt.
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271
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The inositol Inpp5k 5-phosphatase affects osmoregulation through the vasopressin-aquaporin 2 pathway in the collecting system. Pflugers Arch 2011; 462:871-83. [DOI: 10.1007/s00424-011-1028-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 09/04/2011] [Accepted: 09/05/2011] [Indexed: 01/15/2023]
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272
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Abstract
With the exception of the final stages of spermatogenesis in butterfly and some unicellular ciliates and flagellates, ciliated cells undergo cell division without cilia. This reciprocal relationship between cilia formation and cell division has prompted investigators to propose that ciliogenesis and cell cycle progression are mutually exclusive processes. Early work in fibroblasts showed that deciliation occurs in two waves, as cells depart from quiescence. The first wave of deciliation occurs before entry into S, while the second wave occurs between S and mitosis. Since then, it has remained a mystery whether and how (de)ciliation is coupled to the cell cycle and further, whether ciliation can affect cell cycle progression. Several recent publications provide evidence for a causative role of ciliary resorption in influencing the duration of the G1 phase of the cell cycle impacting on several developmental processes, including left-right patterning, kidney, skeletal and brain development. This body of work argues for the existence of a molecular crosstalk between ciliary factors and regulators of the cell cycle. Here, we review the evidence connecting primary cilia and the cell cycle and evaluate the idea that the primary cilium may function as a physical checkpoint in cell cycle re-entry.
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Affiliation(s)
- Sehyun Kim
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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273
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Bachmann-Gagescu R, Phelps IG, Stearns G, Link BA, Brockerhoff SE, Moens CB, Doherty D. The ciliopathy gene cc2d2a controls zebrafish photoreceptor outer segment development through a role in Rab8-dependent vesicle trafficking. Hum Mol Genet 2011; 20:4041-55. [PMID: 21816947 PMCID: PMC3177654 DOI: 10.1093/hmg/ddr332] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Ciliopathies are a genetically and phenotypically heterogeneous group of human developmental disorders whose root cause is the absence or dysfunction of primary cilia. Joubert syndrome is characterized by a distinctive hindbrain malformation variably associated with retinal dystrophy and cystic kidney disease. Mutations in CC2D2A are found in ∼10% of patients with Joubert syndrome. Here we describe the retinal phenotype of cc2d2a mutant zebrafish consisting of disorganized rod and cone photoreceptor outer segments resulting in abnormal visual function as measured by electroretinogram. Our analysis reveals trafficking defects in mutant photoreceptors affecting transmembrane outer segment proteins (opsins) and striking accumulation of vesicles, suggesting a role for Cc2d2a in vesicle trafficking and fusion. This is further supported by mislocalization of Rab8, a key regulator of opsin carrier vesicle trafficking, in cc2d2a mutant photoreceptors and by enhancement of the cc2d2a retinal and kidney phenotypes with partial knockdown of rab8. We demonstrate that Cc2d2a localizes to the connecting cilium in photoreceptors and to the transition zone in other ciliated cell types and that cilia are present in these cells in cc2d2a mutants, arguing against a primary function for Cc2d2a in ciliogenesis. Our data support a model where Cc2d2a, localized at the photoreceptor connecting cilium/transition zone, facilitates protein transport through a role in Rab8-dependent vesicle trafficking and fusion.
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Affiliation(s)
- Ruxandra Bachmann-Gagescu
- HHMI and Division of Basic Science, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA.
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274
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Sang L, Miller JJ, Corbit KC, Giles RH, Brauer MJ, Otto EA, Baye LM, Wen X, Scales SJ, Kwong M, Huntzicker EG, Sfakianos MK, Sandoval W, Bazan JF, Kulkarni P, Garcia-Gonzalo FR, Seol AD, O'Toole JF, Held S, Reutter HM, Lane WS, Rafiq MA, Noor A, Ansar M, Devi ARR, Sheffield VC, Slusarski DC, Vincent JB, Doherty DA, Hildebrandt F, Reiter JF, Jackson PK. Mapping the NPHP-JBTS-MKS protein network reveals ciliopathy disease genes and pathways. Cell 2011; 145:513-28. [PMID: 21565611 DOI: 10.1016/j.cell.2011.04.019] [Citation(s) in RCA: 460] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 03/16/2011] [Accepted: 04/27/2011] [Indexed: 12/18/2022]
Abstract
Nephronophthisis (NPHP), Joubert (JBTS), and Meckel-Gruber (MKS) syndromes are autosomal-recessive ciliopathies presenting with cystic kidneys, retinal degeneration, and cerebellar/neural tube malformation. Whether defects in kidney, retinal, or neural disease primarily involve ciliary, Hedgehog, or cell polarity pathways remains unclear. Using high-confidence proteomics, we identified 850 interactors copurifying with nine NPHP/JBTS/MKS proteins and discovered three connected modules: "NPHP1-4-8" functioning at the apical surface, "NPHP5-6" at centrosomes, and "MKS" linked to Hedgehog signaling. Assays for ciliogenesis and epithelial morphogenesis in 3D renal cultures link renal cystic disease to apical organization defects, whereas ciliary and Hedgehog pathway defects lead to retinal or neural deficits. Using 38 interactors as candidates, linkage and sequencing analysis of 250 patients identified ATXN10 and TCTN2 as new NPHP-JBTS genes, and our Tctn2 mouse knockout shows neural tube and Hedgehog signaling defects. Our study further illustrates the power of linking proteomic networks and human genetics to uncover critical disease pathways.
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Affiliation(s)
- Liyun Sang
- Genentech Inc., South San Francisco, CA 94080, USA
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275
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Agola JO, Jim PA, Ward HH, Basuray S, Wandinger-Ness A. Rab GTPases as regulators of endocytosis, targets of disease and therapeutic opportunities. Clin Genet 2011; 80:305-18. [PMID: 21651512 PMCID: PMC3187864 DOI: 10.1111/j.1399-0004.2011.01724.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Rab GTPases are well-recognized targets in human disease, although are underexplored therapeutically. Elucidation of how mutant or dysregulated Rab GTPases and accessory proteins contribute to organ specific and systemic disease remains an area of intensive study and an essential foundation for effective drug targeting. Mutation of Rab GTPases or associated regulatory proteins causes numerous human genetic diseases. Cancer, neurodegeneration and diabetes represent examples of acquired human diseases resulting from the up- or downregulation or aberrant function of Rab GTPases. The broad range of physiologic processes and organ systems affected by altered Rab GTPase activity is based on pivotal roles in responding to cell signaling and metabolic demand through the coordinated regulation of membrane trafficking. The Rab-regulated processes of cargo sorting, cytoskeletal translocation of vesicles and appropriate fusion with the target membranes control cell metabolism, viability, growth and differentiation. In this review, we focus on Rab GTPase roles in endocytosis to illustrate normal function and the consequences of dysregulation resulting in human disease. Selected examples are designed to illustrate how defects in Rab GTPase cascades alter endocytic trafficking that underlie neurologic, lipid storage, and metabolic bone disorders as well as cancer. Perspectives on potential therapeutic modulation of GTPase activity through small molecule interventions are provided.
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Affiliation(s)
- J O Agola
- Department of Pathology Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
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276
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Waters AM, Beales PL. Ciliopathies: an expanding disease spectrum. Pediatr Nephrol 2011; 26:1039-56. [PMID: 21210154 PMCID: PMC3098370 DOI: 10.1007/s00467-010-1731-7] [Citation(s) in RCA: 491] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 11/02/2010] [Accepted: 11/03/2010] [Indexed: 01/17/2023]
Abstract
Ciliopathies comprise a group of disorders associated with genetic mutations encoding defective proteins, which result in either abnormal formation or function of cilia. As cilia are a component of almost all vertebrate cells, cilia dysfunction can manifest as a constellation of features that include characteristically, retinal degeneration, renal disease and cerebral anomalies. Additional manifestations include congenital fibrocystic diseases of the liver, diabetes, obesity and skeletal dysplasias. Ciliopathic features have been associated with mutations in over 40 genes to date. However, with over 1,000 polypeptides currently identified within the ciliary proteome, several other disorders associated with this constellation of clinical features will likely be ascribed to mutations in other ciliary genes. The mechanisms underlying many of the disease phenotypes associated with ciliary dysfunction have yet to be fully elucidated. Several elegant studies have crucially demonstrated the dynamic ciliary localisation of components of the Hedgehog and Wnt signalling pathways during signal transduction. Given the critical role of the cilium in transducing "outside-in" signals, it is not surprising therefore, that the disease phenotypes consequent to ciliary dysfunction are a manifestation of aberrant signal transduction. Further investigation is now needed to explore the developmental and physiological roles of aberrant signal transduction in the manifestation of ciliopathy phenotypes. Utilisation of conditional and inducible murine models to delete or overexpress individual ciliary genes in a spatiotemporal and organ/cell-specific manner should help clarify some of the functional roles of ciliary proteins in the manifestation of phenotypic features.
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Affiliation(s)
- Aoife M. Waters
- Department of Nephro-Urology, Great Ormond Street Hospital, London, WC1N 3JH UK ,Molecular Medicine Unit, Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
| | - Philip L. Beales
- Molecular Medicine Unit, Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
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277
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Rahman P, Huysmans RD, Wiradjaja F, Gurung R, Ooms LM, Sheffield DA, Dyson JM, Layton MJ, Sriratana A, Takada H, Tiganis T, Mitchell CA. Silencer of death domains (SODD) inhibits skeletal muscle and kidney enriched inositol 5-phosphatase (SKIP) and regulates phosphoinositide 3-kinase (PI3K)/Akt signaling to the actin cytoskeleton. J Biol Chem 2011; 286:29758-70. [PMID: 21712384 DOI: 10.1074/jbc.m111.263103] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Phosphoinositide 3-kinase (PI3K) regulates cell polarity and migration by generating phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P(3)) at the leading edge of migrating cells. The serine-threonine protein kinase Akt binds to PI(3,4,5)P(3), resulting in its activation. Active Akt promotes spatially regulated actin cytoskeletal remodeling and thereby directed cell migration. The inositol polyphosphate 5-phosphatases (5-ptases) degrade PI(3,4,5)P(3) to form PI(3,4)P(2), which leads to diminished Akt activation. Several 5-ptases, including SKIP and SHIP2, inhibit actin cytoskeletal reorganization by opposing PI3K/Akt signaling. In this current study, we identify a molecular co-chaperone termed silencer of death domains (SODD/BAG4) that forms a complex with several 5-ptase family members, including SKIP, SHIP1, and SHIP2. The interaction between SODD and SKIP exerts an inhibitory effect on SKIP PI(3,4,5)P(3) 5-ptase catalytic activity and consequently enhances the recruitment of PI(3,4,5)P(3)-effectors to the plasma membrane. In contrast, SODD(-/-) mouse embryonic fibroblasts exhibit reduced Akt-Ser(473) and -Thr(308) phosphorylation following EGF stimulation, associated with increased SKIP PI(3,4,5)P(3)-5-ptase activity. SODD(-/-) mouse embryonic fibroblasts exhibit decreased EGF-stimulated F-actin stress fibers, lamellipodia, and focal adhesion complexity, a phenotype that is rescued by the expression of constitutively active Akt1. Furthermore, reduced cell migration was observed in SODD(-/-) macrophages, which express the three 5-ptases shown to interact with SODD (SKIP, SHIP1, and SHIP2). Therefore, this study identifies SODD as a novel regulator of PI3K/Akt signaling to the actin cytoskeleton.
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Affiliation(s)
- Parvin Rahman
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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278
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Abstract
PURPOSE OF REVIEW Ciliopathies are genetic disorders caused by defects of primary ciliary structure and/or function and are characterized by pleiotropic clinical features. The ciliopathies include several partially overlapping syndromes such as Joubert syndrome, Bardet-Biedl syndrome and Meckel-Gruber syndrome, all of which have pronounced neurodevelopmental features. Here we focus on potential roles of cilia in central nervous system function, to explore how impairments may cause brain malformation and neurodevelopmental disease. RECENT FINDINGS Cilia have long been considered as 'sensory cellular antennae', responding as chemo-sensors, mechano-sensors and thermo-sensors, although their roles in development were not well understood until recently. The surprising finding that disparate syndromes are all due to defects of the primary cilia, along with the recent advances in genetics, has helped elucidate further roles of primary cilia beyond sensory functions. Several molecules that are associated with key signaling pathways have been discovered in primary cilia. These include sonic hedgehog, wingless, planar cell polarity and fibroblast growth factor, which are essential for many cellular processes. Additionally, mutations in 'ciliome' genes have largely shown developmental defects such as abnormal body axis and brain malformation, implying disrupted cilia-related signaling pathways. Accordingly, the emerging theme is that primary cilia may play roles as modulators of signal transduction to help shape cellular responses within the environmental context during both development and homeostasis. SUMMARY The link between cilia and signal pathways has become a framework for understanding the pathogenesis of ciliopathies. Despite recent progress in ciliary biology, fundamental questions remain about how cilia regulate neuronal function in the central nervous system. Therefore, investigation of ciliary function in the nervous system may reveal cilia-modulating mechanisms in neurodevelopmental processes, as well as suggest new treatments for disease.
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279
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Hu Q, Nelson WJ. Ciliary diffusion barrier: the gatekeeper for the primary cilium compartment. Cytoskeleton (Hoboken) 2011; 68:313-24. [PMID: 21634025 DOI: 10.1002/cm.20514] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 05/04/2011] [Indexed: 11/08/2022]
Abstract
The primary cilium is a cellular antenna that detects and transmits chemical and mechanical cues in the environment through receptors and downstream signal proteins enriched along the ciliary membrane. While it is known that ciliary membrane proteins enter the cilium by way of vesicular and intraflagellar transport, less is known about how ciliary membrane proteins are retained in, and how apical membrane proteins are excluded from the cilium. Here, we review evidence for a membrane diffusion barrier at the base of the primary cilium, and highlight the recent finding of a septin cytoskeleton diffusion barrier. We also discuss candidate ciliopathy genes that may be involved in formation of the barrier, and the role of a diffusion barrier as a common mechanism for compartmentalizing membranes and lipid domains.
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Affiliation(s)
- Qicong Hu
- Department of Biology, Stanford University, Stanford, California 94305., USA
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280
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Finetti F, Paccani SR, Rosenbaum J, Baldari CT. Intraflagellar transport: a new player at the immune synapse. Trends Immunol 2011; 32:139-45. [PMID: 21388881 DOI: 10.1016/j.it.2011.02.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/21/2011] [Accepted: 02/01/2011] [Indexed: 01/21/2023]
Abstract
The assembly and maintenance of primary cilia, which orchestrate signaling pathways centrally implicated in cell proliferation, differentiation and migration, are ensured by multimeric protein particles in a process known as intraflagellar transport (IFT). It has recently been demonstrated that a number of IFT components are expressed in hematopoietic cells, which have no cilia. Here, we summarize data for an unexpected role of IFT proteins in immune synapse assembly and intracellular membrane trafficking in T lymphocytes, and discuss the hypothesis that the immune synapse could represent the functional homolog of the primary cilium in these cells.
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Affiliation(s)
- Francesca Finetti
- Department of Evolutionary Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
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281
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Subcellular spatial regulation of canonical Wnt signalling at the primary cilium. Nat Cell Biol 2011; 13:700-7. [PMID: 21602792 PMCID: PMC3107376 DOI: 10.1038/ncb2259] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 04/13/2011] [Indexed: 12/14/2022]
Abstract
Mechanisms of signal transduction regulation remain a fundamental question in a variety of biological processes and diseases. Previous evidence suggests the primary cilium can act as a signaling hub1, but its exact role in many of its described pathways has remained elusive. Here, we investigate the mechanism of cilia regulation of the canonical Wnt pathway through systematic knock-down and knock-out approaches. We found that the primary cilium dampens canonical Wnt signaling through a unique spatial mechanism involving compartmentalization of signaling components. The cilium, through regulated intraflagellar transport (IFT), diverts Jouberin (Jbn), a ciliopathy protein and context specific Wnt pathway regulator2, away from the nucleus and limits β-catenin nuclear entry. This repressive regulation does not silence the pathway, but instead maintains a discrete range of Wnt responsiveness; cells without cilia have potentiated Wnt responses whereas cells with more than one cilium display inhibited responses. Furthermore, we show that this regulation occurs during embryonic development and is disrupted in cancer cell proliferation. Together these data explain a unique spatial mechanism of regulation of Wnt signaling which may provide insight into ciliary regulation of other signaling pathways.
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282
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Abstract
Diverse developmental and degenerative single-gene disorders such as polycystic kidney disease, nephronophthisis, retinitis pigmentosa, the Bardet–Biedl syndrome, the Joubert syndrome, and the Meckel syndrome may be categorized as ciliopathies — a recent concept that describes diseases characterized by dysfunction of a hairlike cellular organelle called the cilium. Most of the proteins that are altered in these single-gene disorders function at the level of the cilium–centrosome complex, which represents nature’s universal system for cellular detection and management of external signals. Cilia are microtubule-based structures found on almost all vertebrate cells. They originate from a basal body, a modified centrosome, which is the organelle that forms the spindle poles during mitosis. The important role that the cilium–centrosome complex plays in the normal function of most tissues appears to account for the involvement of multiple organ systems in ciliopathies. In this review, we consider the role of the cilium in disease.
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Affiliation(s)
- Friedhelm Hildebrandt
- Howard Hughes Medical Institute, and Department of Pediatrics, University of Michigan Health System, 8220C MSRB III, 1150 W. Medical Center Dr., Ann Arbor, MI 48109-5646, USA.
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283
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Wirschell M, Yamamoto R, Alford L, Gokhale A, Gaillard A, Sale WS. Regulation of ciliary motility: conserved protein kinases and phosphatases are targeted and anchored in the ciliary axoneme. Arch Biochem Biophys 2011; 510:93-100. [PMID: 21513695 DOI: 10.1016/j.abb.2011.04.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/05/2011] [Accepted: 04/06/2011] [Indexed: 12/31/2022]
Abstract
Recent evidence has revealed that the dynein motors and highly conserved signaling proteins are localized within the ciliary 9+2 axoneme. One key mechanism for regulation of motility is phosphorylation. Here, we review diverse evidence, from multiple experimental organisms, that ciliary motility is regulated by phosphorylation/dephosphorylation of the dynein arms through kinases and phosphatases that are anchored immediately adjacent to their axonemal substrates.
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Affiliation(s)
- Maureen Wirschell
- Emory University School of Medicine, Department of Cell Biology, Atlanta, GA 30322, USA.
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284
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Mockel A, Perdomo Y, Stutzmann F, Letsch J, Marion V, Dollfus H. Retinal dystrophy in Bardet-Biedl syndrome and related syndromic ciliopathies. Prog Retin Eye Res 2011; 30:258-74. [PMID: 21477661 DOI: 10.1016/j.preteyeres.2011.03.001] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 03/03/2011] [Accepted: 03/04/2011] [Indexed: 01/26/2023]
Abstract
Primary cilia are almost ubiquitously expressed in eukaryotic cells where they function as sensors relaying information either from the extracellular environment or between two compartments of the same cell, such as in the photoreceptor cell. In ciliopathies, a continuously growing class of genetic disorders related to ciliary defects, the modified primary cilium of the photoreceptor, also known as the connecting cilium, is frequently defective. Ciliary dysfunction involves disturbances in the trafficking and docking of specific proteins involved in its biogenesis or maintenance. The main well-conserved ciliary process, intraflagellar transport (IFT), is a complex process carried out by multimeric ciliary particles and molecular motors of major importance in the photoreceptor cell. It is defective in a growing number of ciliopathies leading to retinal degeneration. Retinitis pigmentosa related to ciliary dysfunction can be an isolated feature or a part of a syndrome such as Bardet-Biedl syndrome (BBS). Research on ciliopathies and BBS has led to the discovery of several major cellular processes carried out by the primary cilium structure and has highlighted their genetic heterogeneity.
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Affiliation(s)
- A Mockel
- Laboratoire de physiopathologie des syndromes rares et héréditaires, Strasbourg, France
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285
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Berry GT. Is prenatal myo-inositol deficiency a mechanism of CNS injury in galactosemia? J Inherit Metab Dis 2011; 34:345-55. [PMID: 21246399 DOI: 10.1007/s10545-010-9260-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 11/23/2010] [Accepted: 11/26/2010] [Indexed: 12/19/2022]
Abstract
Classic Galactosemia due to galactose-1-phosphate uridyltransferase (GALT) deficiency is associated with apparent diet-independent complications including cognitive impairment, learning problems and speech defects. As both galactose-1-phosphate and galactitol may be elevated in cord blood erythrocytes and amniotic fluid despite a maternal lactose-free diet, endogenous production of galactose may be responsible for the elevated fetal galactose metabolites, as well as postnatal CNS complications. A prenatal deficiency of myo-inositol due to an accumulation of both galactose-1- phosphate and galactitol may play a role in the production of the postnatal CNS dysfunction. Two independent mechanisms may result in fetal myo-inositol deficiency: competitive inhibition of the inositol monophosphatase1 (IMPA1)-mediated hydrolysis of inositol monophosphate by high galactose-1- phosphate levels leading to a sequestration of cellular myo-inositol as inositol monophosphate and galactitol-induced reduction in SMIT1-mediated myo-inositol transport. The subsequent reduction of myo-inositol within fetal brain cells could lead to inositide deficiencies with resultant perturbations in calcium and protein kinase C signaling, the AKT/mTOR/ cell growth and development pathway, cell migration, insulin sensitivity, vescular trafficking, endocytosis and exocytosis, actin cytoskeletal remodeling, nuclear metabolism, mRNA export and nuclear pore complex regulation, phosphatidylinositol-anchored proteins, protein phosphorylation and/or endogenous iron "chelation". Using a knockout animal model we have shown that a marked deficiency of myo-inositol in utero is lethal but the phenotype can be rescued by supplementing the drinking water of the pregnant mouse. If myo-inositol deficiency is found to exist in the GALT-deficient fetal brain, then the use of myo-inositol to treat the fetus via oral supplementation of the pregnant female may warrant consideration.
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Affiliation(s)
- Gerard T Berry
- Division of Genetics, Children's Hospital Boston, Center for Life Sciences Building, Boston, MA, 02115, USA.
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286
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Wang F, Ijuin T, Itoh T, Takenawa T. Regulation of IGF-1/PI3K/Akt signalling by the phosphoinositide phosphatase pharbin. J Biochem 2011; 150:83-93. [DOI: 10.1093/jb/mvr037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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287
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Nde1-mediated inhibition of ciliogenesis affects cell cycle re-entry. Nat Cell Biol 2011; 13:351-60. [PMID: 21394081 PMCID: PMC3077088 DOI: 10.1038/ncb2183] [Citation(s) in RCA: 191] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 01/20/2011] [Indexed: 02/07/2023]
Abstract
The primary cilium is an antenna-like organelle that is dynamically regulated during the cell cycle. Ciliogenesis is initiated as cells enter quiescence, while cilium resorption precedes mitosis. The mechanisms coordinating ciliogenesis with the cell cycle are unknown. Here we identify the centrosomal protein, Nde1, as a negative regulator of ciliary length. Nde1 is expressed at high levels in mitosis, low levels in quiescence and localizes at the mother centriole, which nucleates the primary cilium. Cells depleted of Nde1 show longer cilia and a delay in cell cycle re-entry that correlates with ciliary length. Knockdown of Nde1 in zebrafish embryos results in increased ciliary length, suppression of cell division, reduction of the number of cells forming the Kupffer’s vesicle, and left-right patterning defects. These data suggest that Nde1 is an integral component of a network coordinating ciliary length with cell cycle progression and have implications in the transition from quiescence to a proliferative state.
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288
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Abstract
Genetic causes of obesity include the ciliopathies Alström syndrome and Bardet-Biedl syndrome. In these disorders, mutations cause dysfunction of the primary cilium, an organelle involved in intracellular and intercellular sensing and signaling. Alström syndrome is an autosomal-recessive disorder caused solely by mutations in ALMS1. By contrast, Bardet-Biedl syndrome is caused by mutations in at least 14 genes involved in primary cilium function. Despite equivalent levels of obesity, patients with Alström syndrome are more likely than those with Bardet-Biedl syndrome to develop childhood type 2 diabetes mellitus (T2DM), suggesting that ALMS1 might have a specific role in β-cell function and/or peripheral insulin signaling pathways. How mutations in genes that encode proteins involved in primary cilium function lead to the clinical phenotypes of these syndromes is being revealed by work in mutant mouse models. With the aid of these models, insights are being obtained into the pathogenic mechanisms that underlie obesity, insulin resistance and T2DM. Research into ciliopathies, including Alström syndrome and Bardet-Biedl syndrome, should lead not only to improved treatments for individuals with these genetic disorders, but also to improved understanding of the cellular pathways involved in other common causes of obesity and T2DM.
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Affiliation(s)
- Dorothée Girard
- Department of Endocrinology, Flinders Medical Center, Flinders University, Flinders Drive, Bedford Park, Adelaide, SA 5042, Australia
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289
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Abstract
Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease and the most frequent genetic cause of end-stage renal disease up to the third decade of life. It is caused by mutations in 11 different genes, denoted nephrocystins (NPHP1-11, NPHP1L). As an increasing number of these genes are identified, our knowledge of nephronophthisis is changing, thereby improving our understanding of the pathomechanisms in NPHP. Recent publications have described ciliary expression of nephrocystins together with other cystoproteins, such as polycystins 1 and 2 and fibrocystin. These findings have shifted our focus to a pathomechanism involving defects in ciliary function (ciliopathy) and planar cell polarity (PCP). In addition, discoveries of new nephrocystin genes have shown that the disease spectrum of NPHP is much broader than previously anticipated. Different forms of mutations within the same NPHP gene can cause different disease severity. In this review, we highlight the different hypotheses on the pathomechanisms for NPHP and underline the clinical variability of this disease. The clinical spectrum has become even more complex with the possibility of oligogenicity in NPHP.
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Affiliation(s)
- Matthias T F Wolf
- Divison of Pediatric Nephrology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA.
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290
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Otto EA, Ramaswami G, Janssen S, Chaki M, Allen SJ, Zhou W, Airik R, Hurd TW, Ghosh AK, Wolf MT, Hoppe B, Neuhaus TJ, Bockenhauer D, Milford DV, Soliman NA, Saunier S, Johnson CA, Hildebrandt F. Mutation analysis of 18 nephronophthisis associated ciliopathy disease genes using a DNA pooling and next generation sequencing strategy. J Med Genet 2011; 48:105-16. [PMID: 21068128 PMCID: PMC3913043 DOI: 10.1136/jmg.2010.082552] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Nephronophthisis associated ciliopathies (NPHP-AC) comprise a group of autosomal recessive cystic kidney diseases that includes nephronophthisis (NPHP), Senior-Loken syndrome (SLS), Joubert syndrome (JBTS), and Meckel-Gruber syndrome (MKS). To date, causative mutations in NPHP-AC have been described for 18 different genes, rendering mutation analysis tedious and expensive. To overcome the broad genetic locus heterogeneity, a strategy of DNA pooling with consecutive massively parallel resequencing (MPR) was devised. METHODS In 120 patients with severe NPHP-AC phenotypes, five pools of genomic DNA with 24 patients each were prepared which were used as templates in order to PCR amplify all 376 exons of 18 NPHP-AC genes (NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, GLIS2, RPGRIP1L, NEK8, TMEM67, INPP5E, TMEM216, AHI1, ARL13B, CC2D2A, TTC21B, MKS1, and XPNPEP3). PCR products were then subjected to MPR on an Illumina Genome-Analyser and mutations were subsequently assigned to their respective mutation carrier via CEL I endonuclease based heteroduplex screening and confirmed by Sanger sequencing. RESULTS For proof of principle, DNA from patients with known mutations was used and detection of 22 out of 24 different alleles (92% sensitivity) was demonstrated. MPR led to the molecular diagnosis in 30/120 patients (25%) and 54 pathogenic mutations (27 novel) were identified in seven different NPHP-AC genes. Additionally, in 24 patients only single heterozygous variants of unknown significance were found. CONCLUSIONS The combined approach of DNA pooling followed by MPR strongly facilitates mutation analysis in broadly heterogeneous single gene disorders. The lack of mutations in 75% of patients in this cohort indicates further extensive heterogeneity in NPHP-AC.
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Affiliation(s)
- Edgar A. Otto
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Gokul Ramaswami
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Sabine Janssen
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Moumita Chaki
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Susan J. Allen
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Weibin Zhou
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Rannar Airik
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Toby W. Hurd
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Amiya K. Ghosh
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Matthias T. Wolf
- Pediatric Nephrology, Children’s Medical Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Bernd Hoppe
- Department of Pediatrics, Division of Pediatric Nephrology, University Hospital Cologne, Germany
| | - Thomas J. Neuhaus
- Department of Pediatrics, Children’s Hospital Lucerne, Lucerne, Switzerland
| | - Detlef Bockenhauer
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Trust, London, UK
| | - David V. Milford
- Department of Pediatric Nephrology, Birmingham Children’s Hospital, Birmingham, UK
| | - Neveen A. Soliman
- Center of Pediatric Nephrology & Transplantation, Cairo University, Cairo, Egypt
- Egyptian Group for Orphan Renal Diseases (EGORD), Cairo, Egypt
| | - the GPN Study Group, Corinne Antignac
- Department of Genetics, Hopital Necker-Enfants Malades, Assistance Publique–Hopitaux de Paris, Paris, France
- INSERM U-983, Hopital Necker-Enfants Malades, Universite Paris Descartes, Paris, France
| | - Sophie Saunier
- Department of Genetics, Hopital Necker-Enfants Malades, Assistance Publique–Hopitaux de Paris, Paris, France
| | - Colin A. Johnson
- Division of Molecular & Translational Medicine, Leeds Institute of Molecular Medicine, University of Leeds, Leeds, United Kingdom
| | - Friedhelm Hildebrandt
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
- Howard Hughes Medical Institute
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291
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Coppieters F, Lefever S, Leroy BP, De Baere E. CEP290, a gene with many faces: mutation overview and presentation of CEP290base. Hum Mutat 2011; 31:1097-108. [PMID: 20690115 DOI: 10.1002/humu.21337] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ciliopathies are an emerging group of disorders, caused by mutations in ciliary genes. One of the most intriguing disease genes associated with ciliopathies is CEP290, in which mutations cause a wide variety of distinct phenotypes, ranging from isolated blindness over Senior-Loken syndrome (SLS), nephronophthisis (NPHP), Joubert syndrome (related disorders) (JS[RD]), Bardet-Biedl syndrome (BBS), to the lethal Meckel-Grüber syndrome (MKS). Despite the identification of over 100 unique CEP290 mutations, no clear genotype-phenotype correlations could yet be established, and consequently the predictive power of a CEP290-related genotype remains limited. One of the challenges is a better understanding of second-site modifiers. In this respect, there is a growing interest in the potential modifying effects of variations in genes encoding other members of the ciliary proteome that interact with CEP290. Here, we provide an overview of all CEP290 mutations identified so far, with their associated phenotypes. To this end, we developed CEP290base, a locus-specific mutation database that links mutations with patients and their phenotypes (medgen.ugent.be/cep290base).
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Affiliation(s)
- Frauke Coppieters
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
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292
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Sajan SA, Waimey KE, Millen KJ. Novel approaches to studying the genetic basis of cerebellar development. THE CEREBELLUM 2011; 9:272-83. [PMID: 20387026 DOI: 10.1007/s12311-010-0169-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The list of genes that when mutated cause disruptions in cerebellar development is rapidly increasing. The study of both spontaneous and engineered mouse mutants has been essential to this progress, as it has revealed much of our current understanding of the developmental processes required to construct the mature cerebellum. Improvements in brain imaging, such as magnetic resonance imaging (MRI) and the emergence of better classification schemes for human cerebellar malformations, have recently led to the identification of a number of genes which cause human cerebellar disorders. In this review we argue that synergistic approaches combining classical molecular techniques, genomics, and mouse models of human malformations will be essential to fuel additional discoveries of cerebellar developmental genes and mechanisms.
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Affiliation(s)
- Samin A Sajan
- Department of Human Genetics, The University of Chicago, 920 E 58th Street, CLSC 319, Chicago, IL 60637, USA
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293
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Logan CV, Abdel-Hamed Z, Johnson CA. Molecular genetics and pathogenic mechanisms for the severe ciliopathies: insights into neurodevelopment and pathogenesis of neural tube defects. Mol Neurobiol 2010; 43:12-26. [PMID: 21110233 DOI: 10.1007/s12035-010-8154-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 11/16/2010] [Indexed: 01/05/2023]
Abstract
Meckel-Gruber syndrome (MKS) is a severe autosomal recessively inherited disorder characterized by developmental defects of the central nervous system that comprise neural tube defects that most commonly present as occipital encephalocele. MKS is considered to be the most common syndromic form of neural tube defect. MKS is genetically heterogeneous with six known disease genes: MKS1, MKS2/TMEM216, MKS3/TMEM67, RPGRIP1L, CEP290, and CC2D2A with the encoded proteins all implicated in the correct function of primary cilia. Primary cilia are microtubule-based organelles that project from the apical surface of most epithelial cell types. Recent progress has implicated the involvement of cilia in the Wnt and Shh signaling pathways and has led to an understanding of their role in normal mammalian neurodevelopment. The aim of this review is to provide an overview of the molecular genetics of the human disorder, and to assess recent insights into the etiology and molecular cell biology of severe ciliopathies from mammalian animal models of MKS.
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Affiliation(s)
- Clare V Logan
- Section of Ophthalmology and Neurosciences, Wellcome Trust Brenner Building, Leeds Institute of Molecular Medicine, St James's University Hospital, Beckett Street, Leeds LS9 7TF, UK
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294
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Nachury MV, Seeley ES, Jin H. Trafficking to the ciliary membrane: how to get across the periciliary diffusion barrier? Annu Rev Cell Dev Biol 2010; 26:59-87. [PMID: 19575670 DOI: 10.1146/annurev.cellbio.042308.113337] [Citation(s) in RCA: 331] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The primary cilium organizes numerous signal transduction cascades, and an understanding of signaling receptor trafficking to cilia is now emerging. A defining feature of cilia is the periciliary diffusion barrier that separates the ciliary and plasma membranes. Although lateral transport through this barrier may take place, polarized exocytosis to the base of the cilium has been the prevailing model for delivering membrane proteins to cilia. Key players for this polarized exocytosis model include the GTPases Rab8 and Rab11, the exocyst, and possibly the intraflagellar tranport machinery. In turn, the sorting of membrane proteins to cilia critically relies on the recognition of ciliary targeting signals by sorting machines such as the BBSome coat complex or the GTPase Arf4. Finally, some proteins need to exit from cilia, and ubiquitination may regulate this step. The stage is now set to dissect the interplay between signaling and regulated trafficking to and from cilia.
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Affiliation(s)
- Maxence V Nachury
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305-5345, USA.
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295
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Is hearing loss a feature of Joubert syndrome, a ciliopathy? Int J Pediatr Otorhinolaryngol 2010; 74:1034-8. [PMID: 20591505 DOI: 10.1016/j.ijporl.2010.05.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 05/30/2010] [Accepted: 05/31/2010] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To assess if hearing loss is a feature of Joubert syndrome (JBS), one of the ciliopathies and therefore possibly associated with hearing loss. DESIGN Retrospective case series. SETTING University Children's Hospital. PATIENTS Dutch patients with JBS. MAIN OUTCOME MEASURES Audiological data. RESULTS Data from 22 Dutch Joubert syndrome (JBS) cases (17 males, 5 females) aged 3-40 years were available. Audiological tests were successfully performed in 14 cases. Three cases (aged 17-26 years) showed very mild sensorineural hearing loss (SNHL) at different frequencies. Conductive hearing loss due to middle ear infections occurred frequently in young JBS children (6 out of 22 cases). In three cases (aged 3-13 years) the parents reported the child was hypersensitive to sound. CONCLUSION We found no evidence for significant hearing loss in Joubert syndrome patients. However, given the compromised speech development in JBS, conductive hearing loss due to middle ear infections should be treated vigorously. SNHL at a later age cannot be excluded on the basis of our data, given the sample size. Three of the older cases showed discretely increased hearing thresholds. Analogous to the ciliopathy Bardet-Biedl syndrome, where hearing thresholds were reported to be subclinically increased in a group of adolescents patients, we recommend follow-up of JBS patients in view of the possibility of progressive, late-onset SNHL.
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296
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Zhang J, Ravichandran KS, Garrison JC. A key role for the phosphorylation of Ser440 by the cyclic AMP-dependent protein kinase in regulating the activity of the Src homology 2 domain-containing Inositol 5'-phosphatase (SHIP1). J Biol Chem 2010; 285:34839-49. [PMID: 20810657 DOI: 10.1074/jbc.m110.128827] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Src homology 2 domain-containing inositol 5'-phosphatase 1 (SHIP1) dephosphorylates phosphatidylinositol 3,4,5-trisphosphate to phophatidylinositol 3,4-bisphosphate in hematopoietic cells to regulate multiple cell signaling pathways. SHIP1 can be phosphorylated by the cyclic AMP-dependent protein kinase (PKA), resulting in an increase in SHIP1 activity (Zhang, J., Walk, S. F., Ravichandran, K. S., and Garrison, J. C. (2009) J. Biol. Chem. 284, 20070-20078). Using a combination of approaches, we identified the serine residue regulating SHIP1 activity. After mass spectrometric identification of 17 serine and threonine residues on SHIP1 as being phosphorylated by PKA in vitro, studies with truncation mutants of SHIP1 narrowed the phosphorylation site to the catalytic region between residues 400 and 866. Of the two candidate phosphorylation sites located in this region (Ser(440) and Ser(774)), only mutation of Ser(440) to Ala abolished the ability of PKA to phosphorylate the purified, catalytic domain of SHIP1 (residues 401-866). Mutation of Ser(440) to Ala in full-length SHIP1 abrogated the ability of PKA to increase the activity of SHIP1 in mammalian cells. Using flow cytometry, we found that the PKA activator, Sp-adenosine 3',5'-cyclic monophosphorothioate triethylammonium salt hydrate (Sp-cAMPS) blunted the phosphorylation of Akt downstream of B cell antigen receptor engagement in SHIP1-null DT40 B lymphocytes expressing native mouse SHIP1. The inhibitory effect of Sp-cAMPS was absent in cells expressing the S440A mutant of SHIP1. These results suggest that activation of SHIP1 by PKA via phosphorylation on Ser(440) is an important regulatory event in hematopoietic cells.
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Affiliation(s)
- Jun Zhang
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
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297
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Lehman AM, Eydoux P, Doherty D, Glass IA, Chitayat D, Chung BYH, Langlois S, Yong SL, Lowry RB, Hildebrandt F, Trnka P. Co-occurrence of Joubert syndrome and Jeune asphyxiating thoracic dystrophy. Am J Med Genet A 2010; 152A:1411-9. [PMID: 20503315 DOI: 10.1002/ajmg.a.33416] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Ciliary disorders share typical features, such as polydactyly, renal and biliary cystic dysplasia, and retinitis pigmentosa, which often overlap across diagnostic entities. We report on two siblings of consanguineous parents and two unrelated children, both of unrelated parents, with co-occurrence of Joubert syndrome and Jeune asphyxiating thoracic dystrophy, an association that adds to the observation of common final patterns of malformations in ciliary disorders. Using homozygosity mapping in the siblings, we were able to exclude all known genes/loci for both syndromes except for INVS, AHI1, and three genes from the previously described Jeune locus at 15q13. No pathogenic variants were found in these genes by direct sequencing. In the third child reported, sequencing of RPGRIP1L, ARL13B, AHI1, TMEM67, OFD1, CC2D2A, and deletion analysis of NPHP1 showed no mutations. Although this study failed to identify a mutation in the patients tested, the co-occurrence of Joubert and Jeune syndromes is likely to represent a distinct entity caused by mutations in a yet to be discovered gene. The mechanisms by which certain organ systems are affected more than others in the spectrum of ciliary diseases remain largely unknown.
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Affiliation(s)
- A M Lehman
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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298
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Duldulao NA, Li J, Sun Z. Cilia in cell signaling and human disorders. Protein Cell 2010; 1:726-36. [PMID: 21203914 DOI: 10.1007/s13238-010-0098-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Accepted: 07/19/2010] [Indexed: 01/13/2023] Open
Abstract
One of the most widespread cellular organelles in nature is cilium, which is found in many unicellular and multicellular organisms. Formerly thought to be a mostly vestigial organelle, the cilium has been discovered in the past several decades to play critical motile and sensory roles involved in normal organogenesis during development. The role of cilia has also been implicated in an ever increasing array of seemingly unrelated human diseases, including blindness, kidney cysts, neural tube defects and obesity. In this article we review some of the recent developments in research on cilia, and how defects in ciliogenesis and function can give rise to developmental disorders and disease.
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Affiliation(s)
- Neil A Duldulao
- Department of Genetics, Yale University School of Medicine, 333 Cedar St., SHM I-329A, New Haven, CT 06520, USA
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299
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Al-Gazali L, Ali BR. Mutations of a country: a mutation review of single gene disorders in the United Arab Emirates (UAE). Hum Mutat 2010; 31:505-20. [PMID: 20437613 DOI: 10.1002/humu.21232] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The United Arab Emirates inhabitants are ethnically diverse, with ancestries from Arabia, Persia, Baluchistan, and Africa. However, the majority of the current five million inhabitants are expatriates from the Asian subcontinent, Middle Eastern, African, and European countries. Consanguineous marriages within most UAE subpopulations are still the norm, leading to the formation of isolates and higher frequencies of recessive conditions. The UAE is ranked sixth in terms of prevalence of birth defects, with more than 270 genetic disorders reported in the national population. The UAE has high frequencies of blood disorders including thalassemias, sickle cell disease, and G6PD. In addition, certain genetic conditions are relatively common including cystic fibrosis, Joubert, and Meckel syndromes. Furthermore, numerous rare congenital malformations and metabolic disorders have been reported. We review the single gene disorders that have been studied at the molecular level in the UAE (which currently stand at 76) and compile the mutations found. Several novel (p.S2439fs) mutations have been reported including c.7317delA in NF1, c.5C>T (p.A2V) in DKC1, c.1766T>A (p.I589N) in TP63, and c.2117G>T (p.R706L) in VLDLR. We hope that this review will form the basis to establish a UAE mutations database and serve as a model for the collection of mutations of a country.
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Affiliation(s)
- Lihadh Al-Gazali
- Departments of Paediatrics, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates.
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Jin H, White SR, Shida T, Schulz S, Aguiar M, Gygi SP, Bazan JF, Nachury MV. The conserved Bardet-Biedl syndrome proteins assemble a coat that traffics membrane proteins to cilia. Cell 2010; 141:1208-19. [PMID: 20603001 DOI: 10.1016/j.cell.2010.05.015] [Citation(s) in RCA: 461] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 03/19/2010] [Accepted: 04/16/2010] [Indexed: 12/18/2022]
Abstract
The BBSome is a complex of Bardet-Biedl Syndrome (BBS) proteins that shares common structural elements with COPI, COPII, and clathrin coats. Here, we show that the BBSome constitutes a coat complex that sorts membrane proteins to primary cilia. The BBSome is the major effector of the Arf-like GTPase Arl6/BBS3, and the BBSome and GTP-bound Arl6 colocalize at ciliary punctae in an interdependent manner. Strikingly, Arl6(GTP)-mediated recruitment of the BBSome to synthetic liposomes produces distinct patches of polymerized coat apposed onto the lipid bilayer. Finally, the ciliary targeting signal of somatostatin receptor 3 needs to be directly recognized by the BBSome in order to mediate targeting of membrane proteins to cilia. Thus, we propose that trafficking of BBSome cargoes to cilia entails the coupling of BBSome coat polymerization to the recognition of sorting signals by the BBSome.
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Affiliation(s)
- Hua Jin
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5345, USA
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