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Thomas S, Cantagrel V, Mariani L, Serre V, Lee JE, Elkhartoufi N, de Lonlay P, Desguerre I, Munnich A, Boddaert N, Lyonnet S, Vekemans M, Lisgo SN, Caspary T, Gleeson J, Attié-Bitach T. Identification of a novel ARL13B variant in a Joubert syndrome-affected patient with retinal impairment and obesity. Eur J Hum Genet 2015; 23:621-7. [PMID: 25138100 PMCID: PMC4402632 DOI: 10.1038/ejhg.2014.156] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 06/27/2014] [Accepted: 07/09/2014] [Indexed: 12/29/2022] Open
Abstract
Joubert syndrome (JS) is a genetically heterogeneous autosomal recessive ciliopathy with 22 genes implicated to date, including a small, ciliary GTPase, ARL13B. ARL13B is required for cilia formation in vertebrates. JS patients display multiple symptoms characterized by ataxia due to the cerebellar vermis hypoplasia, and that can also include ocular abnormalities, renal cysts, liver fibrosis or polydactyly. These symptoms are shared with other ciliopathies, some of which display additional phenotypes, such as obesity. Here we identified a novel homozygous missense variant in ARL13B/JBTS8 in a JS patient who displayed retinal defects and obesity. We demonstrate the variant disrupts ARL13B function, as its expression did not rescue the mutant phenotype either in Arl13b(scorpion) zebrafish or in Arl13b(hennin) mouse embryonic fibroblasts, while the wild-type ARL13B did. Finally, we show that ARL13B is localized within the primary cilia of neonatal mouse hypothalamic neurons consistent with the known link between hypothalamic ciliary function and obesity. Thus our data identify a novel ARL13B variant that causes JS and retinopathy and suggest an extension of the phenotypic spectrum of ARL13B mutations to obesity.
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Affiliation(s)
- Sophie Thomas
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
| | - Vincent Cantagrel
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
- Laboratory of Neurogenetics, Howard Hughes Medical Institute, Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Laura Mariani
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Valérie Serre
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- UMR7592CNRS, Jacques Monod Institute, Paris Diderot University, Paris, France
| | - Ji-Eun Lee
- Laboratory of Neurogenetics, Howard Hughes Medical Institute, Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Nadia Elkhartoufi
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
- Département de Génétique, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Pascale de Lonlay
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
- Département de Génétique, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Isabelle Desguerre
- Service de neurométabolisme, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Arnold Munnich
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
- Département de Génétique, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Nathalie Boddaert
- Radiologie Pédiatrique et INSERM U-797, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Stanislas Lyonnet
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
- Département de Génétique, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Michel Vekemans
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
- Département de Génétique, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Steven N Lisgo
- The MRC-Wellcome Trust Human Developmental Biology Resource (HDBR), Institute of Genetic Medicine, International Centre for Life, Central Parkway, Newcastle Upon Tyne, UK
| | - Tamara Caspary
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Joseph Gleeson
- Laboratory of Neurogenetics, Howard Hughes Medical Institute, Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA
| | - Tania Attié-Bitach
- INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Paris, France
- Département de Génétique, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
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Damerla RR, Cui C, Gabriel GC, Liu X, Craige B, Gibbs BC, Francis R, Li Y, Chatterjee B, San Agustin JT, Eguether T, Subramanian R, Witman GB, Michaud JL, Pazour GJ, Lo CW. Novel Jbts17 mutant mouse model of Joubert syndrome with cilia transition zone defects and cerebellar and other ciliopathy related anomalies. Hum Mol Genet 2015; 24:3994-4005. [PMID: 25877302 DOI: 10.1093/hmg/ddv137] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 04/13/2015] [Indexed: 11/13/2022] Open
Abstract
Recent studies identified a previously uncharacterized gene C5ORF42 (JBTS17) as a major cause of Joubert syndrome (JBTS), a ciliopathy associated with cerebellar abnormalities and other birth defects. Here we report the first Jbts17 mutant mouse model, Heart Under Glass (Hug), recovered from a forward genetic screen. Exome sequencing identified Hug as a S235P missense mutation in the mouse homolog of JBTS17 (2410089e03rik). Hug mutants exhibit multiple birth defects typical of ciliopathies, including skeletal dysplasia, polydactyly, craniofacial anomalies, kidney cysts and eye defects. Some Hug mutants exhibit congenital heart defects ranging from mild pulmonary stenosis to severe pulmonary atresia. Immunostaining showed JBTS17 is localized in the cilia transition zone. Fibroblasts from Hug mutant mice and a JBTS patient with a JBTS17 mutation showed ciliogenesis defects. Significantly, Hug mutant fibroblasts showed loss of not only JBTS17, but also NPHP1 and CEP290 from the cilia transition zone. Hug mutants exhibited reduced ciliation in the cerebellum. This was associated with reduction in cerebellar foliation. Using a fibroblast wound-healing assay, we showed Hug mutant cells cannot establish cell polarity required for directional cell migration. However, stereocilia patterning was grossly normal in the cochlea, indicating planar cell polarity is not markedly affected. Overall, we showed the JBTS pathophysiology is replicated in the Hug mutant mice harboring a Jbts17 mutation. Our findings demonstrate JBTS17 is a cilia transition zone component that acts upstream of other Joubert syndrome associated transition zone proteins NPHP1 and CEP290, indicating its importance in the pathogenesis of Joubert syndrome.
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Affiliation(s)
- Rama Rao Damerla
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Cheng Cui
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - George C Gabriel
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Xiaoqin Liu
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | - Brian C Gibbs
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Richard Francis
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - You Li
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Bishwanath Chatterjee
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jovenal T San Agustin
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA and
| | - Thibaut Eguether
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA and
| | - Ramiah Subramanian
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | | | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA and
| | - Cecilia W Lo
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA,
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Marzban H, Del Bigio MR, Alizadeh J, Ghavami S, Zachariah RM, Rastegar M. Cellular commitment in the developing cerebellum. Front Cell Neurosci 2015; 8:450. [PMID: 25628535 PMCID: PMC4290586 DOI: 10.3389/fncel.2014.00450] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 12/12/2014] [Indexed: 12/11/2022] Open
Abstract
The mammalian cerebellum is located in the posterior cranial fossa and is critical for motor coordination and non-motor functions including cognitive and emotional processes. The anatomical structure of cerebellum is distinct with a three-layered cortex. During development, neurogenesis and fate decisions of cerebellar primordium cells are orchestrated through tightly controlled molecular events involving multiple genetic pathways. In this review, we will highlight the anatomical structure of human and mouse cerebellum, the cellular composition of developing cerebellum, and the underlying gene expression programs involved in cell fate commitments in the cerebellum. A critical evaluation of the cell death literature suggests that apoptosis occurs in ~5% of cerebellar cells, most shortly after mitosis. Apoptosis and cellular autophagy likely play significant roles in cerebellar development, we provide a comprehensive discussion of their role in cerebellar development and organization. We also address the possible function of unfolded protein response in regulation of cerebellar neurogenesis. We discuss recent advancements in understanding the epigenetic signature of cerebellar compartments and possible connections between DNA methylation, microRNAs and cerebellar neurodegeneration. Finally, we discuss genetic diseases associated with cerebellar dysfunction and their role in the aging cerebellum.
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Affiliation(s)
- Hassan Marzban
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
| | - Marc R Del Bigio
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada ; Department of Pathology, University of Manitoba Winnipeg, MB, Canada
| | - Javad Alizadeh
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
| | - Saeid Ghavami
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
| | - Robby M Zachariah
- Department of Biochemistry and Medical Genetics, University of Manitoba Winnipeg, MB, Canada ; Regenerative Medicine Program, University of Manitoba Winnipeg, MB, Canada
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics, University of Manitoba Winnipeg, MB, Canada ; Regenerative Medicine Program, University of Manitoba Winnipeg, MB, Canada
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Abstract
The role of primary cilia in adult neurons remains elusive, however their developmental functions during brain morphogenesis have been recently highlighted thanks to mouse models. Unmistakably, they are needed for Hedgehog (Hh)-dependent patterning in the forebrain. Not only for Hh reception itself, but most importantly for a downstream event in the Hh transduction pathway, independent of Hh ligand: the Gli3 processing. Indeed, phenotypes due to cilia disruption in the developing brain, such as early patterning, olfactory bulb or corpus callosum formation, can be rescued by reintroducing Gli3-R (the short truncated form of Gli3 working as a transcriptional repressor of Hh target gene). In addition, primary cilia control the proliferation rate in different neural progenitors in the cortex, the hippocampus and the cerebellum; they are required for proper migration of interneurons. And cilia dysfunction is correlated with hydrocephaly, synaptogenesis defects and aberrant axonal tract projections. Most of these neurodevelopmental defects can be related to the various neurological features frequently observed across the ciliopathy spectrum. And thus, understanding the underlying mechanisms of these diverse functions of primary cilia in the brain is a new fundamental challenge.
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Affiliation(s)
- Christine Laclef
- Laboratoire de biologie du développement, UPMC Université Paris 6, UMR 7622 CNRS, U969 Inserm, 9, quai Saint Bernard, 75005 Paris, France
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Wilde JJ, Petersen JR, Niswander L. Genetic, epigenetic, and environmental contributions to neural tube closure. Annu Rev Genet 2014; 48:583-611. [PMID: 25292356 DOI: 10.1146/annurev-genet-120213-092208] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The formation of the embryonic brain and spinal cord begins as the neural plate bends to form the neural folds, which meet and adhere to close the neural tube. The neural ectoderm and surrounding tissues also coordinate proliferation, differentiation, and patterning. This highly orchestrated process is susceptible to disruption, leading to neural tube defects (NTDs), a common birth defect. Here, we highlight genetic and epigenetic contributions to neural tube closure. We describe an online database we created as a resource for researchers, geneticists, and clinicians. Neural tube closure is sensitive to environmental influences, and we discuss disruptive causes, preventative measures, and possible mechanisms. New technologies will move beyond candidate genes in small cohort studies toward unbiased discoveries in sporadic NTD cases. This will uncover the genetic complexity of NTDs and critical gene-gene interactions. Animal models can reveal the causative nature of genetic variants, the genetic interrelationships, and the mechanisms underlying environmental influences.
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Affiliation(s)
- Jonathan J Wilde
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Children's Hospital Colorado, Aurora, Colorado 80045;
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Meckel-Gruber Syndrome: a population-based study on prevalence, prenatal diagnosis, clinical features, and survival in Europe. Eur J Hum Genet 2014; 23:746-52. [PMID: 25182137 DOI: 10.1038/ejhg.2014.174] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 07/05/2014] [Accepted: 08/01/2014] [Indexed: 11/08/2022] Open
Abstract
Meckel-Gruber Syndrome is a rare autosomal recessive lethal ciliopathy characterized by the triad of cystic renal dysplasia, occipital encephalocele and postaxial polydactyly. We present the largest population-based epidemiological study to date using data provided by the European Surveillance of Congenital Anomalies (EUROCAT) network. The study population consisted of 191 cases of MKS identified between January 1990 and December 2011 in 34 European registries. The mean prevalence was 2.6 per 100,000 births in a subset of registries with good ascertainment. The prevalence was stable over time, but regional differences were observed. There were 145 (75.9%) terminations of pregnancy after prenatal diagnosis, 13 (6.8%) fetal deaths, 33 (17.3%) live births. In addition to cystic kidneys (97.7%), encephalocele (83.8%) and polydactyly (87.3%), frequent features include other central nervous system anomalies (51.4%), fibrotic/cystic changes of the liver (65.5% of cases with post mortem examination) and orofacial clefts (31.8%). Various other anomalies were present in 64 (37%) patients. As nowadays most patients are detected very early in pregnancy when liver or kidney changes may not yet be developed or may be difficult to assess, none of the anomalies should be considered obligatory for the diagnosis. Most cases (90.2%) are diagnosed prenatally at 14.3 ± 2.6 (range 11-36) gestational weeks and pregnancies are mainly terminated, reducing the number of LB to one-fifth of the total prevalence rate. Early diagnosis is important for timely counseling of affected couples regarding the option of pregnancy termination and prenatal genetic testing in future pregnancies.
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57
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Apkon SD, Grady R, Hart S, Lee A, McNalley T, Niswander L, Petersen J, Remley S, Rotenstein D, Shurtleff H, Warner M, Walker WO. Advances in the care of children with spina bifida. Adv Pediatr 2014; 61:33-74. [PMID: 25037124 DOI: 10.1016/j.yapd.2014.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Susan D Apkon
- Rehabilitation Medicine, University of Washington, Seattle, WA, USA; Rehabilitation Medicine, Seattle Children's Hospital, 4800 Sand Point Way Northeast, M/S OB-8414, Seattle, WA 98105, USA.
| | - Richard Grady
- Section of Pediatric Urology, Seattle Children's Hospital, University of Washington School of Medicine, 4800 Sand Point Way Northeast, Seattle, WA 98105, USA
| | - Solveig Hart
- Rehabilitation Services, Seattle Children's Hospital, 4800 Sand Point Way Northeast, Seattle, WA 98105, USA
| | - Amy Lee
- Pediatric Neurosurgery, Seattle Children's Hospital, University of Washington, 4800 Sand Point Way Northeast, M/S W7729, PO Box 5371, Seattle, WA 98105, USA
| | - Thomas McNalley
- Rehabilitation Medicine, Seattle Children's Hospital, University of Washington, 4800 Sand Point Way Northeast, M/S OB-8404, Seattle, WA 98105, USA
| | - Lee Niswander
- Department of Pediatrics, Children's Hospital Colorado, Howard Hughes Medical Institute, University of Colorado School of Medicine, Mail Stop 8133, Building RC1 South, Room L18-12106, 12801 East 17th Avenue, Aurora, CO 80045, USA
| | - Juliette Petersen
- Molecular Biology Program, University of Colorado Denver Anschutz Medical Campus, Mail Stop 8133, Building RC1 South, L18-12400D, 12801 East 17th Avenue, Aurora, CO 80045, USA
| | - Sheridan Remley
- Rehabilitation Services, Seattle Children's Hospital, 4800 Sand Point Way Northeast, Seattle, WA 98105, USA
| | - Deborah Rotenstein
- Pediatric Endocrinology, Endocrine Division, Pediatric Alliance, 1789 South Braddock Avenue, Suite 294, Pittsburgh, PA 15218, USA
| | - Hillary Shurtleff
- Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA; Department of Child Psychiatry, Seattle Children's Hospital, 4800 Sand Point Way Northeast, Seattle, WA 98105, USA
| | - Molly Warner
- Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA; Neuropsychology Consult Service, Department of Psychiatry, Seattle Children's Hospital, 4800 Sand Point Way Northeast, Seattle, WA 98105, USA
| | - William O Walker
- Division of Developmental Medicine, Seattle Children's Hospital, University of Washington School of Medicine, 4800 Sand Point Way Northeast, M/S OC.9.940, Seattle, WA 98105, USA
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Taverna E, Götz M, Huttner WB. The cell biology of neurogenesis: toward an understanding of the development and evolution of the neocortex. Annu Rev Cell Dev Biol 2014; 30:465-502. [PMID: 25000993 DOI: 10.1146/annurev-cellbio-101011-155801] [Citation(s) in RCA: 513] [Impact Index Per Article: 51.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neural stem and progenitor cells have a central role in the development and evolution of the mammalian neocortex. In this review, we first provide a set of criteria to classify the various types of cortical stem and progenitor cells. We then discuss the issue of cell polarity, as well as specific subcellular features of these cells that are relevant for their modes of division and daughter cell fate. In addition, cortical stem and progenitor cell behavior is placed into a tissue context, with consideration of extracellular signals and cell-cell interactions. Finally, the differences across species regarding cortical stem and progenitor cells are dissected to gain insight into key developmental and evolutionary mechanisms underlying neocortex expansion.
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Affiliation(s)
- Elena Taverna
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany;
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Murine Joubert syndrome reveals Hedgehog signaling defects as a potential therapeutic target for nephronophthisis. Proc Natl Acad Sci U S A 2014; 111:9893-8. [PMID: 24946806 DOI: 10.1073/pnas.1322373111] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Nephronophthisis (NPHP) is the major cause of pediatric renal failure, yet the disease remains poorly understood, partly due to the lack of appropriate animal models. Joubert syndrome (JBTS) is an inherited ciliopathy giving rise to NPHP with cerebellar vermis aplasia and retinal degeneration. Among patients with JBTS and a cerebello-oculo-renal phenotype, mutations in CEP290 (NPHP6) are the most common genetic lesion. We present a Cep290 gene trap mouse model of JBTS that displays the kidney, eye, and brain abnormalities that define the syndrome. Mutant mice present with cystic kidney disease as neonates. Newborn kidneys contain normal amounts of lymphoid enhancer-binding factor 1 (Lef1) and transcription factor 1 (Tcf1) protein, indicating normal function of the Wnt signaling pathway; however, an increase in the protein Gli3 repressor reveals abnormal Hedgehog (Hh) signaling evident in newborn kidneys. Collecting duct cells from mutant mice have abnormal primary cilia and are unable to form spheroid structures in vitro. Treatment of mutant cells with the Hh agonist purmorphamine restored normal spheroid formation. Renal epithelial cells from a JBTS patient with CEP290 mutations showed similar impairments to spheroid formation that could also be partially rescued by exogenous stimulation of Hh signaling. These data implicate abnormal Hh signaling as the cause of NPHP and suggest that Hh agonists may be exploited therapeutically.
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60
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Poretti A, Boltshauser E, Doherty D. Cerebellar hypoplasia: Differential diagnosis and diagnostic approach. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2014; 166C:211-26. [DOI: 10.1002/ajmg.c.31398] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ferent J, Traiffort E. Hedgehog: Multiple Paths for Multiple Roles in Shaping the Brain and Spinal Cord. Neuroscientist 2014; 21:356-71. [PMID: 24743306 DOI: 10.1177/1073858414531457] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Since the discovery of the segment polarity gene Hedgehog in Drosophila three decades ago, our knowledge of Hedgehog signaling pathway has considerably improved and paved the way to a wide field of investigations in the developing and adult central nervous system. Its peculiar transduction mechanism together with its implication in tissue patterning, neural stem cell biology, and neural tissue homeostasis make Hedgehog pathway of interest in a high number of normal or pathological contexts. Consistent with its role during brain development, misregulation of Hedgehog signaling is associated with congenital diseases and tumorigenic processes while its recruitment in damaged neural tissue may be part of the repairing process. This review focuses on the most recent data regarding the Hedgehog pathway in the developing and adult central nervous system and also its relevance as a therapeutic target in brain and spinal cord diseases.
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Affiliation(s)
- Julien Ferent
- IRCM, Molecular Biology of Neural Development, Montreal, Quebec, Canada
| | - Elisabeth Traiffort
- INSERM-Université Paris Sud, Neuroprotection and Neuroregeneration: Small Neuroactive Molecules UMR 788, Le Kremlin-Bicêtre, France
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62
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Ruat M, Faure H, Daynac M. Smoothened, Stem Cell Maintenance and Brain Diseases. TOPICS IN MEDICINAL CHEMISTRY 2014. [DOI: 10.1007/7355_2014_83] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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63
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Abstract
Primary cilia are generally solitary organelles that emanate from the surface of almost all vertebrate cell types. Until recently, details regarding the function of these structures were lacking; however, extensive evidence now suggests that primary cilia have critical roles in sensing the extracellular environment, and in coordinating developmental and homeostatic signalling pathways. Furthermore, disruption of these functions seems to underlie a diverse spectrum of disorders, known as primary ciliopathies. These disorders are characterized by wide-ranging clinical and genetic heterogeneity, but with substantial overlap among distinct conditions. Indeed, ciliopathies are associated with a large variety of manifestations that often include distinctive neurological findings. Herein, we review neurological features associated with primary ciliopathies, highlight genotype-phenotype correlations, and discuss potential mechanisms underlying these findings.
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Filges I, Nosova E, Bruder E, Tercanli S, Townsend K, Gibson WT, Röthlisberger B, Heinimann K, Hall JG, Gregory-Evans CY, Wasserman WW, Miny P, Friedman JM. Exome sequencing identifies mutations in KIF14 as a novel cause of an autosomal recessive lethal fetal ciliopathy phenotype. Clin Genet 2013; 86:220-8. [PMID: 24128419 DOI: 10.1111/cge.12301] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 09/29/2013] [Accepted: 10/11/2013] [Indexed: 12/21/2022]
Abstract
Gene discovery using massively parallel sequencing has focused on phenotypes diagnosed postnatally such as well-characterized syndromes or intellectual disability, but is rarely reported for fetal disorders. We used family-based whole-exome sequencing in order to identify causal variants for a recurrent pattern of an undescribed lethal fetal congenital anomaly syndrome. The clinical signs included intrauterine growth restriction (IUGR), severe microcephaly, renal cystic dysplasia/agenesis and complex brain and genitourinary malformations. The phenotype was compatible with a ciliopathy, but not diagnostic of any known condition. We hypothesized biallelic disruption of a gene leading to a defect related to the primary cilium. We identified novel autosomal recessive truncating mutations in KIF14 that segregated with the phenotype. Mice with autosomal recessive mutations in the same gene have recently been shown to have a strikingly similar phenotype. Genotype-phenotype correlations indicate that the function of KIF14 in cell division and cytokinesis can be linked to a role in primary cilia, supported by previous cellular and model organism studies of proteins that interact with KIF14. We describe the first human phenotype, a novel lethal ciliary disorder, associated with biallelic inactivating mutations in KIF14. KIF14 may also be considered a candidate gene for allelic viable ciliary and/or microcephaly phenotypes.
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Affiliation(s)
- I Filges
- Department of Medical Genetics, University of British Columbia, and Child and Family Research Institute, Vancouver, Canada; Division of Medical Genetics, Department of Biomedicine, University Hospital, Basel, Switzerland
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65
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Abstract
Joubert syndrome is a congenital cerebellar ataxia with autosomal recessive or X-linked inheritance, the diagnostic hallmark of which is a unique cerebellar and brainstem malformation recognisable on brain imaging-the so-called molar tooth sign. Neurological signs are present from the neonatal period and include hypotonia progressing to ataxia, global developmental delay, ocular motor apraxia, and breathing dysregulation. These signs are variably associated with multiorgan involvement, mainly of the retina, kidneys, skeleton, and liver. 21 causative genes have been identified so far, all of which encode for proteins of the primary cilium or its apparatus. The primary cilium is a subcellular organelle that has key roles in development and in many cellular functions, making Joubert syndrome part of the expanding family of ciliopathies. Notable clinical and genetic overlap exists between distinct ciliopathies, which can co-occur even within families. Such variability is probably explained by an oligogenic model of inheritance, in which the interplay of mutations, rare variants, and polymorphisms at distinct loci modulate the expressivity of the ciliary phenotype.
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