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Baizer JS. Neuroanatomy of autism: what is the role of the cerebellum? Cereb Cortex 2024; 34:94-103. [PMID: 38696597 DOI: 10.1093/cercor/bhae050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 01/08/2024] [Accepted: 01/25/2024] [Indexed: 05/04/2024] Open
Abstract
Autism (or autism spectrum disorder) was initially defined as a psychiatric disorder, with the likely cause maternal behavior (the very destructive "refrigerator mother" theory). It took several decades for research into brain mechanisms to become established. Both neuropathological and imaging studies found differences in the cerebellum in autism spectrum disorder, the most widely documented being a decreased density of Purkinje cells in the cerebellar cortex. The popular interpretation of these results is that cerebellar neuropathology is a critical cause of autism spectrum disorder. We challenge that view by arguing that if fewer Purkinje cells are critical for autism spectrum disorder, then any condition that causes the loss of Purkinje cells should also cause autism spectrum disorder. We will review data on damage to the cerebellum from cerebellar lesions, tumors, and several syndromes (Joubert syndrome, Fragile X, and tuberous sclerosis). Collectively, these studies raise the question of whether the cerebellum really has a role in autism spectrum disorder. Autism spectrum disorder is now recognized as a genetically caused developmental disorder. A better understanding of the genes that underlie the differences in brain development that result in autism spectrum disorder is likely to show that these genes affect the development of the cerebellum in parallel with the development of the structures that do underlie autism spectrum disorder.
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Affiliation(s)
- Joan S Baizer
- Department of Physiology and Biophysics, 123 Sherman Hall, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214, United States
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Cuppari C, Salpietro A, Ceravolo I, Iapadre G, Fusco M, Sallemi A, Mancuso A, Farello G, Ceravolo MD. Ciliopathies: Genetic Counseling. JOURNAL OF PEDIATRIC NEUROLOGY 2022. [DOI: 10.1055/s-0042-1759515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
AbstractJoubert syndrome (JS) follows autosomal recessive inheritance, with rare X-linked recessive cases. The disease is genetically heterogeneous with neurological features associated with multiorgan involvement (e.g., retinal dystrophy, nephronophthisis, hepatic fibrosis, and polydactyly). The incidence of JS and related disorders is between 1/80,000 and 1/100,000 live births. Many causative genes have been identified, all encoding for proteins of the cilium or the centrosome, making the JS part of a group of diseases called “ciliopathies.” The identification of the molecular defect in couples at risk is allowed by prenatal genetic testing, whereas fetal ultrasound and brain neuroimaging are informative in the first and second trimester of pregnancy.
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Affiliation(s)
- Caterina Cuppari
- Unit of Pediatric Emergency, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi,” University of Messina, Messina, Italy
| | | | - Ida Ceravolo
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Giulia Iapadre
- Department of Pediatrics, University of L'Aquila, Coppito, Italy
| | - Monica Fusco
- Unit of Pediatric Emergency, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi,” University of Messina, Messina, Italy
| | - Alessia Sallemi
- Unit of Pediatric Emergency, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi,” University of Messina, Messina, Italy
| | - Alessio Mancuso
- Unit of Pediatric Emergency, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi,” University of Messina, Messina, Italy
| | - Giovanni Farello
- Pediatric Clinic, Department of Life, Health and Environmental Sciences, University of L'Aquila, Coppito (AQ), Italy
| | - Maria Domenica Ceravolo
- Unit of Pediatric Emergency, Department of Human Pathology of the Adult and Developmental Age “Gaetano Barresi,” University of Messina, Messina, Italy
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Mansour F, Boivin FJ, Shaheed IB, Schueler M, Schmidt-Ott KM. The Role of Centrosome Distal Appendage Proteins (DAPs) in Nephronophthisis and Ciliogenesis. Int J Mol Sci 2021; 22:ijms222212253. [PMID: 34830133 PMCID: PMC8621283 DOI: 10.3390/ijms222212253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 02/06/2023] Open
Abstract
The primary cilium is found in most mammalian cells and plays a functional role in tissue homeostasis and organ development by modulating key signaling pathways. Ciliopathies are a group of genetically heterogeneous disorders resulting from defects in cilia development and function. Patients with ciliopathic disorders exhibit a range of phenotypes that include nephronophthisis (NPHP), a progressive tubulointerstitial kidney disease that commonly results in end-stage renal disease (ESRD). In recent years, distal appendages (DAPs), which radially project from the distal end of the mother centriole, have been shown to play a vital role in primary ciliary vesicle docking and the initiation of ciliogenesis. Mutations in the genes encoding these proteins can result in either a complete loss of the primary cilium, abnormal ciliary formation, or defective ciliary signaling. DAPs deficiency in humans or mice commonly results in NPHP. In this review, we outline recent advances in our understanding of the molecular functions of DAPs and how they participate in nephronophthisis development.
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Affiliation(s)
- Fatma Mansour
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; (F.M.); (F.J.B.)
- Molecular and Translational Kidney Research, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Department of Pathology, Faculty of Veterinary Medicine, Cairo University, 12613 Giza, Egypt;
| | - Felix J. Boivin
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; (F.M.); (F.J.B.)
- Molecular and Translational Kidney Research, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Iman B. Shaheed
- Department of Pathology, Faculty of Veterinary Medicine, Cairo University, 12613 Giza, Egypt;
| | - Markus Schueler
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; (F.M.); (F.J.B.)
- Correspondence: (M.S.); (K.M.S.-O.)
| | - Kai M. Schmidt-Ott
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; (F.M.); (F.J.B.)
- Molecular and Translational Kidney Research, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Correspondence: (M.S.); (K.M.S.-O.)
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Oda Y, Yoshida K, Furutani C, Wakita A, Hama Y, Miyauchi M, Okada Y. Treatment of dental caries in a patient with Joubert syndrome without the use of sedatives: A case study. SPECIAL CARE IN DENTISTRY 2021; 41:411-416. [PMID: 33544393 DOI: 10.1111/scd.12572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Joubert syndrome (JS) is a rare autosomal recessive inherited ciliopathy caused by gene mutation. Manifestations can include intermittent dyspnea, apnea, ataxia, and other nervous system abnormalities. CASE PRESENTATION The patient was a 21-year-old female with JS, severe intellectual disability, cerebral palsy, and epilepsy. Dental caries in both mandibular lower first molars was diagnosed by a local dentist, and the patient was referred to us for further treatment. Although her oral hygiene was good, the dental caries had reached the vicinity of the dental pulp. The caries had developed symmetrically on both first molars and was completely covered with the gingiva. As she was hesitant to receive treatment without anxiolysis, we considered using general anesthesia or intravenous sedation. However, we were recommended against it by the patient's family doctor because of the risk of apneic episodes in JS. Accordingly, dental treatment was performed over multiple days through physical behavior adjustment, while providing oxygenation (3 L/min) in preparation for an apneic episode. The dental treatment was successfully completed with a good postoperative outcome. CONCLUSIONS Dental treatment can be safely performed in patients with JS through physical behavior adjustment, thereby minimizing the risk of an apnea attack.
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Affiliation(s)
- Yuki Oda
- Department of Special Care Dentistry, Hiroshima University Hospital, Hiroshima, Japan
| | - Keita Yoshida
- Department of Anesthesiology, Osaka Dental University Hospital, Osaka, Japan
| | - Chiaki Furutani
- Department of Special Care Dentistry, Hiroshima University Hospital, Hiroshima, Japan
| | - Atsuko Wakita
- Dental Hygienists Section, Hiroshima University Hospital, Hiroshima, Japan
| | - Yoko Hama
- Hiroshima Oral Health Center, Hiroshima, Japan
| | | | - Yoshiyuki Okada
- Department of Special Care Dentistry, Hiroshima University Hospital, Hiroshima, Japan
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Imaging phenotype correlation with molecular and molecular pathway defects in malformations of cortical development. Pediatr Radiol 2020; 50:1974-1987. [PMID: 33252763 DOI: 10.1007/s00247-020-04674-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/23/2020] [Accepted: 03/31/2020] [Indexed: 10/22/2022]
Abstract
The increase in understanding of molecular biology and recent advances in genetic testing have caused rapid growth in knowledge of genetic causes of malformations of cortical development. Imaging diagnosis of malformations of cortical development can be made prenatally in a large subset of fetuses based on the presence of specific deviations from the normal pattern of development, characteristic imaging features, and associated non-central-nervous-system (CNS) abnormalities. In this review the authors discuss the role of four key cell molecules/molecular pathways in corticogenesis that are frequently implicated in complex prenatally diagnosed malformations of cortical development. The authors also list the currently described genes causing defects in these molecules/molecular pathways when mutated, and the constellation of imaging findings resultant of such defects.
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Pedersen AF, Meyer DN, Petriv AMV, Soto AL, Shields JN, Akemann C, Baker BB, Tsou WL, Zhang Y, Baker TR. Nanoplastics impact the zebrafish (Danio rerio) transcriptome: Associated developmental and neurobehavioral consequences. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 266:115090. [PMID: 32693326 PMCID: PMC7492438 DOI: 10.1016/j.envpol.2020.115090] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 06/05/2020] [Accepted: 06/22/2020] [Indexed: 05/20/2023]
Abstract
Microplastics (MPs) are a ubiquitous pollutant detected not only in marine and freshwater bodies, but also in tap and bottled water worldwide. While MPs have been extensively studied, the toxicity of their smaller counterpart, nanoplastics (NPs), is not well documented. Despite likely large-scale human and animal exposure to NPs, the associated health risks remain unclear, especially during early developmental stages. To address this, we investigated the health impacts of exposures to both 50 and 200 nm polystyrene NPs in larval zebrafish. From 6 to 120 h post-fertilization (hpf), developing zebrafish were exposed to a range of fluorescent NPs (10-10,000 parts per billion). Dose-dependent increases in accumulation were identified in exposed larval fish, potentially coinciding with an altered behavioral response as evidenced through swimming hyperactivity. Notably, exposures did not impact mortality, hatching rate, or deformities; however, transcriptomic analysis suggests neurodegeneration and motor dysfunction at both high and low concentrations. Furthermore, results of this study suggest that NPs can accumulate in the tissues of larval zebrafish, alter their transcriptome, and affect behavior and physiology, potentially decreasing organismal fitness in contaminated ecosystems. The uniquely broad scale of this study during a critical window of development provides crucial multidimensional characterization of NP impacts on human and animal health.
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Affiliation(s)
- Adam F Pedersen
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA
| | - Danielle N Meyer
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA; Department of Pharmacology - School of Medicine, Wayne State University, 540 E Canfield, Detroit, MI, 28201, USA
| | - Anna-Maria V Petriv
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA
| | - Abraham L Soto
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA
| | - Jeremiah N Shields
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA
| | - Camille Akemann
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA; Department of Pharmacology - School of Medicine, Wayne State University, 540 E Canfield, Detroit, MI, 28201, USA
| | - Bridget B Baker
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA
| | - Wei-Ling Tsou
- Department of Pharmacology - School of Medicine, Wayne State University, 540 E Canfield, Detroit, MI, 28201, USA
| | - Yongli Zhang
- College of Engineering, Wayne State University, 5050 Anthony Wayne Dr, Detroit, MI, 28201, USA
| | - Tracie R Baker
- Institute of Environmental Health Sciences, Wayne State University, 6135 Woodward Ave, Detroit, MI, 48202, USA; Department of Pharmacology - School of Medicine, Wayne State University, 540 E Canfield, Detroit, MI, 28201, USA.
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Abstract
The cerebellum is a pivotal centre for the integration and processing of motor and sensory information. Its extended development into the postnatal period makes this structure vulnerable to a variety of pathologies, including neoplasia. These properties have prompted intensive investigations that reveal not only developmental mechanisms in common with other regions of the neuraxis but also unique strategies to generate neuronal diversity. How the phenotypically distinct cell types of the cerebellum emerge rests on understanding how gene expression differences arise in a spatially and temporally coordinated manner from initially homogeneous cell populations. Increasingly sophisticated fate mapping approaches, culminating in genetic-induced fate mapping, have furthered the understanding of lineage relationships between early- versus later-born cells. Tracing the developmental histories of cells in this way coupled with analysis of gene expression patterns has provided insight into the developmental genetic programmes that instruct cellular heterogeneity. A limitation to date has been the bulk analysis of cells, which blurs lineage relationships and obscures gene expression differences between cells that underpin the cellular taxonomy of the cerebellum. This review emphasises recent discoveries, focusing mainly on single-cell sequencing in mouse and parallel human studies that elucidate neural progenitor developmental trajectories with unprecedented resolution. Complementary functional studies of neural repair after cerebellar injury are challenging assumptions about the stability of postnatal cellular identities. The result is a wealth of new information about the developmental mechanisms that generate cerebellar neural diversity, with implications for human evolution.
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Affiliation(s)
- Max J. van Essen
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Samuel Nayler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Esther B. E. Becker
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - John Jacob
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Zebrafish dscaml1 Deficiency Impairs Retinal Patterning and Oculomotor Function. J Neurosci 2019; 40:143-158. [PMID: 31685652 DOI: 10.1523/jneurosci.1783-19.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/15/2019] [Accepted: 10/22/2019] [Indexed: 11/21/2022] Open
Abstract
Down syndrome cell adhesion molecules (dscam and dscaml1) are essential regulators of neural circuit assembly, but their roles in vertebrate neural circuit function are still mostly unexplored. We investigated the functional consequences of dscaml1 deficiency in the larval zebrafish (sexually undifferentiated) oculomotor system, where behavior, circuit function, and neuronal activity can be precisely quantified. Genetic perturbation of dscaml1 resulted in deficits in retinal patterning and light adaptation, consistent with its known roles in mammals. Oculomotor analyses revealed specific deficits related to the dscaml1 mutation, including severe fatigue during gaze stabilization, reduced saccade amplitude and velocity in the light, greater disconjugacy, and impaired fixation. Two-photon calcium imaging of abducens neurons in control and dscaml1 mutant animals confirmed deficits in saccade-command signals (indicative of an impairment in the saccadic premotor pathway), whereas abducens activation by the pretectum-vestibular pathway was not affected. Together, we show that loss of dscaml1 resulted in impairments in specific oculomotor circuits, providing a new animal model to investigate the development of oculomotor premotor pathways and their associated human ocular disorders.SIGNIFICANCE STATEMENT Dscaml1 is a neural developmental gene with unknown behavioral significance. Using the zebrafish model, this study shows that dscaml1 mutants have a host of oculomotor (eye movement) deficits. Notably, the oculomotor phenotypes in dscaml1 mutants are reminiscent of human ocular motor apraxia, a neurodevelopmental disorder characterized by reduced saccade amplitude and gaze stabilization deficits. Population-level recording of neuronal activity further revealed potential subcircuit-specific requirements for dscaml1 during oculomotor behavior. These findings underscore the importance of dscaml1 in the development of visuomotor function and characterize a new model to investigate potential circuit deficits underlying human oculomotor disorders.
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Kumar D, Mains RE, Eipper BA, King SM. Ciliary and cytoskeletal functions of an ancient monooxygenase essential for bioactive amidated peptide synthesis. Cell Mol Life Sci 2019; 76:2329-2348. [PMID: 30879092 PMCID: PMC6529398 DOI: 10.1007/s00018-019-03065-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/28/2019] [Accepted: 03/07/2019] [Indexed: 02/07/2023]
Abstract
Many secreted peptides used for cell-cell communication require conversion of a C-terminal glycine to an amide for bioactivity. This reaction is catalyzed only by the integral membrane protein peptidylglycine α-amidating monooxygenase (PAM). PAM has been highly conserved and is found throughout the metazoa; PAM-like sequences are also present in choanoflagellates, filastereans, unicellular and colonial chlorophyte green algae, dinoflagellates and haptophytes. Recent studies have revealed that in addition to playing a key role in peptidergic signaling, PAM also regulates ciliogenesis in vertebrates, planaria and chlorophyte algae, and is required for the stability of actin-based microvilli. Here we briefly introduce the basic principles involved in ciliogenesis, the sequential reactions catalyzed by PAM and the trafficking of PAM through the secretory and endocytic pathways. We then discuss the multi-faceted roles this enzyme plays in the formation and maintenance of cytoskeleton-based cellular protrusions and propose models for how PAM protein and amidating activity might contribute to ciliogenesis. Finally, we consider why some ciliated organisms lack PAM, and discuss the potential ramifications of ciliary localized PAM for the endocrine features commonly observed in patients with ciliopathies.
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Affiliation(s)
- Dhivya Kumar
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Betty A Eipper
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Stephen M King
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA.
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Bashford AL, Subramanian V. Mice with a conditional deletion of Talpid3 (KIAA0586) - a model for Joubert syndrome. J Pathol 2019; 248:396-408. [PMID: 30924151 PMCID: PMC6767539 DOI: 10.1002/path.5271] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 03/07/2019] [Accepted: 03/26/2019] [Indexed: 12/14/2022]
Abstract
Joubert syndrome (JS) is a ciliopathy associated with mutations in numerous genes encoding cilia components. TALPID3 encoded by KIAA0856 in man (2700049A03Rik in mouse) is a centrosomal protein essential for the assembly of primary cilia. Mutations in KIAA0856 have been recently identified in JS patients. Herein, we describe a novel mouse JS model with a conditional deletion of the conserved exons 11–12 of Talpid3 in the central nervous system which recapitulates the complete cerebellar phenotype seen in JS. Talpid3 mutant mice exhibit key hallmarks of JS including progressive ataxia, severely hypoplastic cerebellar hemispheres and vermis, together with abnormal decussation of the superior cerebellar peduncles. The Purkinje cell layer is disorganised with abnormal dendritic arborisation. The external granule layer (EGL) is thinner, lacks primary cilia, and has a reduced level of proliferation. Furthermore, we describe novel cellular defects including ectopic clusters of mature granule neurons, and abnormal parallel fibre‐derived synapses and disorientation of cells in the EGL. The defective glial scaffold results in abnormal granule cell migration which manifests as ectopic clusters of granule neurons. In addition, we show a reduction in Wnt7a expression suggesting that defects may arise not only from deficiencies in the Hedgehog (Hh) pathway but also due to the additional roles of Talpid3. The Talpid3 conditional knockout mouse is a novel JS model which fully recapitulates the JS cerebellar phenotype. These findings reveal a role for Talpid3 in granule precursor cell migration in the cerebellum (either direct or indirect) which together with defective Hh signalling underlies the JS phenotype. Our findings also illustrate the utility of creating conditional mouse models to assist in unravelling the molecular and cellular mechanisms underlying JS. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Andrew L Bashford
- Department of Biology and Biochemistry, University of Bath, Bath, UK
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Zhu L, Chen L, Yan L, Perkins BD, Li S, Li B, Xu HA, Li XJ. Mutant Ahi1 Affects Retinal Axon Projection in Zebrafish via Toxic Gain of Function. Front Cell Neurosci 2019; 13:81. [PMID: 30949029 PMCID: PMC6438259 DOI: 10.3389/fncel.2019.00081] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 02/18/2019] [Indexed: 12/23/2022] Open
Abstract
Joubert syndrome (JBTS) is an inherited autosomal recessive disorder associated with cerebellum and brainstem malformation and can be caused by mutations in the Abelson helper integration site-1 (AHI1) gene. Although AHI1 mutations in humans cause abnormal cerebellar development and impaired axonal decussation in JBTS, these phenotypes are not robust or are absent in various mouse models with Ahi1 mutations. AHI1 contains an N-terminal coiled-coil domain, multiple WD40 repeats, and a C-terminal Src homology 3 (SH3) domain, suggesting that AHI1 functions as a signaling or scaffolding protein. Since most AHI1 mutations in humans can result in truncated AHI1 proteins lacking WD40 repeats and the SH3 domain, it remains unclear whether mutant AHI1 elicits toxicity via a gain-of-function mechanism by the truncated AHI1. Because Ahi1 in zebrafish and humans share a similar N-terminal region with a coiled-coil domain that is absent in mouse Ahi1, we used zebrafish as a model to investigate whether Ahi1 mutations could affect axonal decussation. Using in situ hybridization, we found that ahi1 is highly expressed in zebrafish ocular tissues, especially in retina, allowing us to examine its effect on retinal ganglion cell (RGC) projection and eye morphology. We injected a morpholino to zebrafish embryos, which can generate mutant Ahi1 lacking the intact WD40 repeats, and found RGC axon misprojection and ocular dysplasia in 4 dpf (days post-fertilization) larvae after the injection. However, ahi1 null zebrafish showed normal RGC axon projection and ocular morphology. We then used CRISPR/Cas9 to generate truncated ahi1 and also found similar defects in the RGC axon projection as seen in those injected with ahi1 morpholino. Thus, the aberrant retinal axon projection in zebrafish is caused by the presence of mutant ahi1 rather than the loss of ahi1, suggesting that mutant Ahi1 may affect axonal decussation via toxic gain of function.
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Affiliation(s)
- Louyin Zhu
- School of Life Sciences and Institute of Life Science, Nanchang University, Nanchang, China.,Jiangxi Provincial Collaborative Innovation Center for Cardiovascular, Digestive and Neuropsychiatric Diseases, Nanchang, China.,Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, United States
| | - Laiqiang Chen
- School of Life Sciences and Institute of Life Science, Nanchang University, Nanchang, China.,Guangdong-Hongkong-Macau Institute of CNS Regeneration (GHMICR), Jinan University, Guangzhou, China
| | - Lingya Yan
- School of Life Sciences and Institute of Life Science, Nanchang University, Nanchang, China
| | - Brian D Perkins
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, United States
| | - Shihua Li
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, United States
| | - Baoming Li
- School of Life Sciences and Institute of Life Science, Nanchang University, Nanchang, China.,Jiangxi Provincial Collaborative Innovation Center for Cardiovascular, Digestive and Neuropsychiatric Diseases, Nanchang, China
| | - Hong A Xu
- School of Life Sciences and Institute of Life Science, Nanchang University, Nanchang, China.,Jiangxi Provincial Collaborative Innovation Center for Cardiovascular, Digestive and Neuropsychiatric Diseases, Nanchang, China
| | - Xiao-Jiang Li
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, United States
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Abstract
INTRODUCTION Joubert syndrome (JS) is a rare autosomal recessive inherited disease belonging to ciliopathy with the causative mutation of genes. Except for X-linked inheritance, the high recurrence rate of a family is about 25%. After birth, it may cause a series of neurological symptoms, even with retina, kidney, liver, and other organ abnormalities, which is defined as Joubert syndrome and related disorders (JSRD). Molecular genetics research contributes to disease prediction and genetic counseling. Prenatal diagnosis is rare. Magnetic resonance imaging (MRI) is usually the first-choice diagnostic modality with typical brain images characterized by the molar tooth sign. We describe a case of JS prenatally and Dandy-Walker malformation for the differential diagnosis based on ultrasonograms. We also review the etiology, imaging features, clinical symptoms, and diagnosis of JSRD. CASE PRESENTATION A 22-year-old woman was pregnant at 27 1/7 weeks' gestation with fetal cerebellar vermis hypoplasia. Fetal ultrasonography and MRI confirmed a diagnosis of JS at our center. The couple finally opted to terminate the fetus, which had a normal appearance and growth parameters. The couple also had an AHI1 gene mutation on chromosome 6. CONCLUSIONS Currently, a diagnosis of JS is commonly made after birth. Fewer cases of prenatal diagnosis by ultrasonography have been made, and they are more liable to be misdirected because of some nonspecial features that also manifest in Dandy-Walker malformation, cranio-cerebello-cardiac syndrome, and so on.
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Furtado MB, Merriner DJ, Berger S, Rhodes D, Jamsai D, O'Bryan MK. Mutations in the Katnb1 gene cause left-right asymmetry and heart defects. Dev Dyn 2017; 246:1027-1035. [PMID: 28791777 DOI: 10.1002/dvdy.24564] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/27/2017] [Accepted: 08/01/2017] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The microtubule-severing protein complex katanin is composed two subunits, the ATPase subunit, KATNA1, and the noncatalytic regulatory subunit, KATNB1. Recently, the Katnb1 gene has been linked to infertility, regulation of centriole and cilia formation in fish and mammals, as well as neocortical brain development. KATNB1 protein is expressed in germ cells in humans and mouse, mitotic/meiotic spindles and cilia, although the full expression pattern of the Katnb1 gene has not been described. RESULTS Using a knockin-knockout mouse model of Katnb1 dysfunction we demonstrate that Katnb1 is ubiquitously expressed during embryonic development, although a stronger expression is seen in the crown cells of the gastrulation organizer, the murine node. Furthermore, null and hypomorphic Katnb1 gene mutations show a novel correlation between Katnb1 dysregulation and the development of impaired left-right signaling, including cardiac malformations. CONCLUSIONS Katanin function is a critical regulator of heart development in mice. These findings are potentially relevant to human cardiac development. Developmental Dynamics 246:1027-1035, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Milena B Furtado
- The Jackson Laboratory, Bar Harbor, Maine.,Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia
| | - D Jo Merriner
- The Development and Stem Cells Program of Monash Biomedicine Discovery Institute and The Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia.,The School of Biological Sciences, 25 Rainforest Walk, Monash University, Melbourne, Australia
| | - Silke Berger
- Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia
| | - Danielle Rhodes
- The Development and Stem Cells Program of Monash Biomedicine Discovery Institute and The Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Duangporn Jamsai
- The Development and Stem Cells Program of Monash Biomedicine Discovery Institute and The Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Moira K O'Bryan
- The Development and Stem Cells Program of Monash Biomedicine Discovery Institute and The Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia.,The School of Biological Sciences, 25 Rainforest Walk, Monash University, Melbourne, Australia
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14
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Seylanian Toosi F, Boloursaz S, Abbasi B, Hekmat R, Mortazavi Ardestani R, Mohajerzadeh M. Joubert syndrome; misleading presentation of two cases as pseudo-tumor cerebri and literature review. J Renal Inj Prev 2017; 6:76-79. [PMID: 28497078 PMCID: PMC5423287 DOI: 10.15171/jrip.2017.14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 10/25/2016] [Indexed: 12/29/2022] Open
Abstract
Joubert syndrome is a rare autosomal recessive disorder that may have different clinical presentation such as ataxia, hyperpnea, sleep apnea, nystagmus, hypotonia, seizure and retinitis pigmentosa. We present a 22-year-old girl and her older sibling, labeled as cerebral palsy. She had renal transplant years ago without the true diagnosis of the disorder. Brain imaging revealed the classic "molar tooth sign" appearance, and clinical evaluation established the diagnosis for both of the siblings. Imaging should be done to evaluate the neuroradiological findings of Joubert syndrome. With a neonate with Joubert syndrome in a family, antenatal diagnosis by ultrasound is crucial for future siblings.
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Affiliation(s)
| | - Samineh Boloursaz
- Department of Radiology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Bita Abbasi
- Department of Radiology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Reza Hekmat
- Department of Nephrology, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | - Mina Mohajerzadeh
- Department of Radiology, Mashhad University of Medical Sciences, Mashhad, Iran
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15
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Kishimoto K, Nomura J, Ellegood J, Fukumoto K, Lerch JP, Moreno-De-Luca D, Bourgeron T, Tamada K, Takumi T. Behavioral and neuroanatomical analyses in a genetic mouse model of 2q13 duplication. Genes Cells 2017; 22:436-451. [PMID: 28370817 DOI: 10.1111/gtc.12487] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 02/24/2017] [Indexed: 12/12/2022]
Abstract
Duplications of human chromosome 2q13 have been reported in patients with neurodevelopmental disorder including autism spectrum disorder. Nephronophthisis-1 (NPHP1) was identified as a causative gene in the minimal deletion on chromosome 2q13 for familial juvenile type 1 nephronophthisis and Joubert syndrome, an autosomal recessive neurodevelopmental disorder characterized by a cerebellar and brain stem malformation, hypotonia, developmental delay, ataxia, and sometimes associated with cognitive impairment. NPHP1 encodes a ciliary protein, nephrocystin-1, which is expressed in the brain, yet its function in the brain remains largely unknown. In this study, we generated bacterial artificial chromosome-based transgenic mice, called 2q13 dup, that recapitulate human chromosome 2q13 duplication and contain one extra copy of the Nphp1 transgene. To analyze any behavioral alterations in 2q13 dup mice, we conducted a battery of behavioral tests. Although 2q13 dup mice show no significant differences in social behavior, they show deficits in spontaneous alternation behavior and fear memory. We also carried out magnetic resonance imaging to confirm whether copy number gain in this locus affects the neuroanatomy. There was a trend toward a decrease in the cerebellar paraflocculus of 2q13 dup mice. This is the first report of a genetic mouse model for human 2q13 duplication.
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Affiliation(s)
- Keiko Kishimoto
- RIKEN Brain Science Institute (BSI), Wako, Saitama, 351-0198, Japan.,Graduate School of Biomedical Sciences, Hiroshima University, Minami, Hiroshima, 734-8553, Japan
| | - Jun Nomura
- RIKEN Brain Science Institute (BSI), Wako, Saitama, 351-0198, Japan
| | - Jacob Ellegood
- Mouse Imaging Centre (MICe), Hospital for Sick Children, Toronto, ON, M5T 3H7, Canada
| | - Keita Fukumoto
- RIKEN Brain Science Institute (BSI), Wako, Saitama, 351-0198, Japan.,Graduate School of Biomedical Sciences, Hiroshima University, Minami, Hiroshima, 734-8553, Japan
| | - Jason P Lerch
- Mouse Imaging Centre (MICe), Hospital for Sick Children, Toronto, ON, M5T 3H7, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON, M5S 1A1, Canada
| | - Daniel Moreno-De-Luca
- Division of Child and Adolescent Psychiatry, Department of Psychiatry and Human Behavior, Brown University, Providence, RI, 02908, USA
| | | | - Kota Tamada
- RIKEN Brain Science Institute (BSI), Wako, Saitama, 351-0198, Japan
| | - Toru Takumi
- RIKEN Brain Science Institute (BSI), Wako, Saitama, 351-0198, Japan.,Graduate School of Biomedical Sciences, Hiroshima University, Minami, Hiroshima, 734-8553, Japan
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16
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Abstract
Primary cilia are small, antenna-like structures that detect mechanical and chemical cues and transduce extracellular signals. While mammalian primary cilia were first reported in the late 1800s, scientific interest in these sensory organelles has burgeoned since the beginning of the twenty-first century with recognition that primary cilia are essential to human health. Among the most common clinical manifestations of ciliary dysfunction are renal cysts. The molecular mechanisms underlying renal cystogenesis are complex, involving multiple aberrant cellular processes and signaling pathways, while initiating molecular events remain undefined. Autosomal Dominant Polycystic Kidney Disease is the most common renal cystic disease, caused by disruption of polycystin-1 and polycystin-2 transmembrane proteins, which evidence suggests must localize to primary cilia for proper function. To understand how the absence of these proteins in primary cilia may be remediated, we review intracellular trafficking of polycystins to the primary cilium. We also examine the controversial mechanisms by which primary cilia transduce flow-mediated mechanical stress into intracellular calcium. Further, to better understand ciliary function in the kidney, we highlight the LKB1/AMPK, Wnt, and Hedgehog developmental signaling pathways mediated by primary cilia and misregulated in renal cystic disease.
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17
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Hong CJ, Hamilton BA. Zfp423 Regulates Sonic Hedgehog Signaling via Primary Cilium Function. PLoS Genet 2016; 12:e1006357. [PMID: 27727273 PMCID: PMC5065120 DOI: 10.1371/journal.pgen.1006357] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 09/09/2016] [Indexed: 11/17/2022] Open
Abstract
Zfp423 encodes a 30-zinc finger transcription factor that intersects several canonical signaling pathways. Zfp423 mutations result in ciliopathy-related phenotypes, including agenesis of the cerebellar vermis in mice and Joubert syndrome (JBTS19) and nephronophthisis (NPHP14) in humans. Unlike most ciliopathy genes, Zfp423 encodes a nuclear protein and its developmental expression is complex, leading to alternative proposals for cellular mechanisms. Here we show that Zfp423 is expressed by cerebellar granule cell precursors, that loss of Zfp423 in these precursors leads to cell-intrinsic reduction in proliferation, loss of response to Shh, and primary cilia abnormalities that include diminished frequency of both Smoothened and IFT88 localization. Loss of Zfp423 alters expression of several genes encoding key cilium components, including increased expression of Tulp3. Tulp3 is a direct binding target of Zfp423 and reducing the overexpression of Tulp3 in Zfp423-deficient cells suppresses Smoothened translocation defects. These results define Zfp423 deficiency as a bona fide ciliopathy, acting upstream of Shh signaling, and indicate a mechanism intrinsic to granule cell precursors for the resulting cerebellar hypoplasia.
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Affiliation(s)
- Chen-Jei Hong
- Department of Cellular & Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, California, United States of America.,Department of Medicine, University of California, San Diego School of Medicine, La Jolla, California, United States of America.,Moores UCSD Cancer Center, University of California, San Diego School of Medicine, La Jolla, California, United States of America.,Institute for Genomic Medicine, University of California, San Diego School of Medicine, La Jolla, California, United States of America
| | - Bruce A Hamilton
- Department of Cellular & Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, California, United States of America.,Department of Medicine, University of California, San Diego School of Medicine, La Jolla, California, United States of America.,Moores UCSD Cancer Center, University of California, San Diego School of Medicine, La Jolla, California, United States of America.,Institute for Genomic Medicine, University of California, San Diego School of Medicine, La Jolla, California, United States of America
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18
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Ferraro S, Gomez-Montalvo AI, Olmos R, Ramirez M, Lamas M. Primary cilia in rat mature Müller glia: downregulation of IFT20 expression reduces sonic hedgehog-mediated proliferation and dedifferentiation potential of Müller glia primary cultures. Cell Mol Neurobiol 2014; 35:533-42. [PMID: 25504432 DOI: 10.1007/s10571-014-0149-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/08/2014] [Indexed: 11/26/2022]
Abstract
Primary cilia are specialized organelles that extend from the cell surface and concentrate signal transduction components. In the nervous system, primary cilia-associated signals, such as sonic hedgehog (Shh), regulate cell proliferation and neuronal fate. Primary cilia assembly and maintenance require a multi-subunit intraflagellar transport (IFT) protein complex. Defects in primary cilia and IFT proteins are associated to severe pathological phenotypes. In the retina, the study of primary cilia has been mainly restricted to the specialized photoreceptor outer segment. The presence and physiological role of primary cilia in other retinal cells have not been clearly elucidated. Müller cells are the main glia of the retina where they exert distinct functions to maintain homeostasis. In pathological conditions, Müller cells mount a unique regenerative response through the processes of dedifferentiation, proliferation, and differentiation into neuronal lineages. The involvement of IFT proteins or a primary cilium in these processes has not been explored. In this study, we used mature Müller glia primary cultures to reveal the presence of the primary cilia by immunoreactivity to acetylated α-tubulin and γ-tubulin, which localize to the axoneme and ciliar basal body, respectively. We demonstrate that si-RNA-mediated downregulation of IFT20 gene expression, a main component of the IFT machinery, blocks Shh-induced Müller cell proliferation. We present evidence that IFT20 ablation impairs the dedifferentiation capacity of Müller cells induced by Shh and by glutamate. Our demonstration that Müller glia expresses IFT20 and harbors primary cilia, and opens new venues of research on the role of primary cilia in the retina.
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Affiliation(s)
- Silene Ferraro
- Departamento de Farmacobiología, CINVESTAV Sede Sur, Calzada de los Tenorios 235, Mexico, DF, Mexico
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19
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Rao Y, Hao R, Wang B, Yao TP. A Mec17-Myosin II Effector Axis Coordinates Microtubule Acetylation and Actin Dynamics to Control Primary Cilium Biogenesis. PLoS One 2014; 9:e114087. [PMID: 25494100 PMCID: PMC4262394 DOI: 10.1371/journal.pone.0114087] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 11/04/2014] [Indexed: 01/31/2023] Open
Abstract
Primary cilia are specialized, acetylated microtubule-based signaling processes. Cilium assembly is activated by cellular quiescence and requires reconfiguration of microtubules, the actin cytoskeleton, and vesicular trafficking machinery. How these components are coordinated to activate ciliogenesis remains unknown. Here we identify the microtubule acetyltransferase Mec-17 and myosin II motors as the key effectors in primary cilium biogenesis. We found that myosin IIB (Myh10) is required for cilium formation; however, myosin IIA (Myh9) suppresses it. Myh10 binds and antagonizes Myh9 to increase actin dynamics, which facilitates the assembly of the pericentrosomal preciliary complex (PPC) that supplies materials for cilium growth. Importantly, Myh10 expression is upregulated by serum-starvation and this induction requires Mec-17, which is itself accumulated upon cellular quiescence. Pharmacological stimulation of microtubule acetylation also induces Myh10 expression and cilium formation. Thus cellular quiescence induces Mec17 to couple the production of acetylated microtubules and Myh10, whose accumulation overcomes the inhibitory role of Myh9 and initiates ciliogenesis.
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Affiliation(s)
- Yanhua Rao
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Rui Hao
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Bin Wang
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Tso-Pang Yao
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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20
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The ciliary proteins Meckelin and Jouberin are required for retinoic acid-dependent neural differentiation of mouse embryonic stem cells. Differentiation 2014; 87:134-146. [PMID: 24613594 DOI: 10.1016/j.diff.2014.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 01/23/2014] [Accepted: 02/17/2014] [Indexed: 12/29/2022]
Abstract
The dysfunction of the primary cilium, a complex, evolutionarily conserved, organelle playing an important role in sensing and transducing cell signals, is the unifying pathogenetic mechanism of a growing number of diseases collectively termed "ciliopathies", typically characterized by multiorgan involvement. Developmental defects of the central nervous system (CNS) characterize a subset of ciliopathies showing clinical and genetic overlap, such as Joubert syndrome (JS) and Meckel syndrome (MS). Although several knock-out mice lacking a variety of ciliary proteins have shown the importance of primary cilia in the development of the brain and CNS-derived structures, developmental in vitro studies, extremely useful to unravel the role of primary cilia along the course of neural differentiation, are still missing. Mouse embryonic stem cells (mESCs) have been recently proven to mimic brain development, giving the unique opportunity to dissect the CNS differentiation process along its sequential steps. In the present study we show that mESCs express the ciliary proteins Meckelin and Jouberin in a developmentally-regulated manner, and that these proteins co-localize with acetylated tubulin labeled cilia located at the outer embryonic layer. Further, mESCs differentiating along the neuronal lineage activate the cilia-dependent sonic hedgehog signaling machinery, which is impaired in Meckelin knock-out cells but results unaffected in Jouberin-deficient mESCs. However, both lose the ability to acquire a neuronal phenotype. Altogether, these results demonstrate a pivotal role of Meckelin and Jouberin during embryonic neural specification and indicate mESCs as a suitable tool to investigate the developmental impact of ciliary proteins dysfunction.
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21
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Liu WL, Li F, He ZX, Jiang HY, Ai R, Huang J, Li B. A novel case of natural killer cell deficiency associated with Joubert syndrome. Int J Neurosci 2013; 123:587-90. [PMID: 23509923 DOI: 10.3109/00207454.2013.783031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Joubert syndrome (JS) is a rare, complex autosomal recessive inherited disorder mostly characterized by partial or complete agenesis of the cerebellar vermis. There is a wide clinical and genetic heterogeneity in the syndrome. The main clinical features of JS are hypotonia, ataxia, developmental delay, oculomotor apraxia, breathing abnormalities and peculiar neuroimaging findings. A lot of additional features have been reported. Here, we first reported a case of the syndrome with natural killer (NK) cell deficiency. NK cell deficiency in JS might be not an incidental phenomenon. NK cell deficiency might be associated with JS when there are additional features such as recurrent infections and tumors. NK cell deficiency may be part of the clinical spectrum of JS. Reduced cellular immunity in association with NK cell deficiency may be a feature in a subset of JS patients, especially if there is a history of recurrent infections, tumors and autoimmune disorders.
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Affiliation(s)
- Wei-Liang Liu
- Department of Pediatrics, Affiliated Hospital of Guiyang Medical College, Guiyang, China.
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22
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Abdelhamed ZA, Wheway G, Szymanska K, Natarajan S, Toomes C, Inglehearn C, Johnson CA. Variable expressivity of ciliopathy neurological phenotypes that encompass Meckel-Gruber syndrome and Joubert syndrome is caused by complex de-regulated ciliogenesis, Shh and Wnt signalling defects. Hum Mol Genet 2013; 22:1358-72. [PMID: 23283079 DOI: 10.1093/hmg/dds546] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The ciliopathies are a group of heterogeneous diseases with considerable variations in phenotype for allelic conditions such as Meckel-Gruber syndrome (MKS) and Joubert syndrome (JBTS) even at the inter-individual level within families. In humans, mutations in TMEM67 (also known as MKS3) cause both MKS and JBTS, with TMEM67 encoding the orphan receptor meckelin (TMEM67) that localizes to the ciliary transition zone. We now describe the Tmem67(tm1(Dgen/H)) knockout mouse model that recapitulates the brain phenotypic variability of these human ciliopathies, with categorization of Tmem67 mutant animals into two phenotypic groups. An MKS-like incipient congenic group (F6 to F10) manifested very variable neurological features (including exencephaly, and frontal/occipital encephalocele) that were associated with the loss of primary cilia, diminished Shh signalling and dorsalization of the caudal neural tube. The 'MKS-like' group also had high de-regulated canonical Wnt/β-catenin signalling associated with hyper-activated Dishevelled-1 (Dvl-1) localized to the basal body. Conversely, a second fully congenic group (F > 10) had less variable features pathognomonic for JBTS (including cerebellar hypoplasia), and retention of abnormal bulbous cilia associated with mild neural tube ventralization. The 'JBTS-like' group had de-regulated low levels of canonical Wnt signalling associated with the loss of Dvl-1 localization to the basal body. Our results suggest that modifier alleles partially determine the variation between MKS and JBTS, implicating the interaction between Dvl-1 and meckelin, or other components of the ciliary transition zone. The Tmem67(tm1(Dgen/H)) line is unique in modelling the variable expressivity of phenotypes in these two ciliopathies.
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Affiliation(s)
- Zakia A Abdelhamed
- Ciliopathy Research Group, Section of Ophthalmology and Neurosciences, Leeds Institute of Molecular Medicine, University of Leeds, Leeds, UK
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23
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Photoreceptor sensory cilia and ciliopathies: focus on CEP290, RPGR and their interacting proteins. Cilia 2012; 1:22. [PMID: 23351659 PMCID: PMC3563624 DOI: 10.1186/2046-2530-1-22] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 09/19/2012] [Indexed: 02/08/2023] Open
Abstract
Ciliopathies encompass a broad array of clinical findings associated with genetic defects in biogenesis and/or function of the primary cilium, a ubiquitous organelle involved in the transduction of diverse biological signals. Degeneration or dysfunction of retinal photoreceptors is frequently observed in diverse ciliopathies. The sensory cilium in a photoreceptor elaborates into unique outer segment discs that provide extensive surface area for maximal photon capture and efficient visual transduction. The daily renewal of approximately 10% of outer segments requires a precise control of ciliary transport. Here, we review the ciliopathies with associated retinal degeneration, describe the distinctive structure of the photoreceptor cilium, and discuss mouse models that allow investigations into molecular mechanisms of cilia biogenesis and defects. We have specifically focused on two ciliary proteins - CEP290 and RPGR - that underlie photoreceptor degeneration and syndromic ciliopathies. Mouse models of CEP290 and RPGR disease, and of their multiple interacting partners, have helped unravel new functional insights into cell type-specific phenotypic defects in distinct ciliary proteins. Elucidation of multifaceted ciliary functions and associated protein complexes will require concerted efforts to assimilate diverse datasets from in vivo and in vitro studies. We therefore discuss a possible framework for investigating genetic networks associated with photoreceptor cilia biogenesis and pathology.
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24
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Analysis of human samples reveals impaired SHH-dependent cerebellar development in Joubert syndrome/Meckel syndrome. Proc Natl Acad Sci U S A 2012; 109:16951-6. [PMID: 23027964 DOI: 10.1073/pnas.1201408109] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Joubert syndrome (JS) and Meckel syndrome (MKS) are pleiotropic ciliopathies characterized by severe defects of the cerebellar vermis, ranging from hypoplasia to aplasia. Interestingly, ciliary conditional mutant mice have a hypoplastic cerebellum in which the proliferation of cerebellar granule cell progenitors (GCPs) in response to Sonic hedgehog (SHH) is severely reduced. This suggests that Shh signaling defects could contribute to the vermis hypoplasia observed in the human syndromes. As existing JS/MKS mutant mouse models suggest apparently contradictory hypotheses on JS/MKS etiology, we investigated Shh signaling directly on human fetal samples. First, in an examination of human cerebellar development, we linked the rates of GCP proliferation to the different levels and localizations of active Shh signaling and showed that the GCP possessed a primary cilium with CEP290 at its base. Second, we found that the proliferation of GCPs and their response to SHH were severely impaired in the cerebellum of subjects with JS/MKS and Jeune syndrome. Finally, we showed that the defect in GCP proliferation was similar in the cerebellar vermis and hemispheres in all patients with ciliopathy analyzed, suggesting that the specific cause of vermal hypo-/aplasia precedes this defect. Our results, obtained from the analysis of human samples, show that the hemispheres and the vermis are affected in JS/MKS and provide evidence of a defective cellular mechanism in these pathologic processes.
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25
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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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26
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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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27
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Ruat M, Roudaut H, Ferent J, Traiffort E. Hedgehog trafficking, cilia and brain functions. Differentiation 2012; 83:S97-104. [DOI: 10.1016/j.diff.2011.11.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 11/21/2011] [Accepted: 11/22/2011] [Indexed: 10/14/2022]
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28
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Vogel P, Read RW, Hansen GM, Payne BJ, Small D, Sands AT, Zambrowicz BP. Congenital Hydrocephalus in Genetically Engineered Mice. Vet Pathol 2011; 49:166-81. [DOI: 10.1177/0300985811415708] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is evidence that genetic factors play a role in the complex multifactorial pathogenesis of hydrocephalus. Identification of the genes involved in the development of this neurologic disorder in animal models may elucidate factors responsible for the excessive accumulation of cerebrospinal fluid in hydrocephalic humans. The authors report here a brief summary of findings from 12 lines of genetically engineered mice that presented with autosomal recessive congenital hydrocephalus. This study illustrates the value of knockout mice in identifying genetic factors involved in the development of congenital hydrocephalus. Findings suggest that dysfunctional motile cilia represent the underlying pathogenetic mechanism in 8 of the 12 lines ( Ulk4, Nme5, Nme7, Kif27, Stk36, Dpcd, Ak7, and Ak8). The likely underlying cause in the remaining 4 lines ( RIKEN 4930444A02, Celsr2, Mboat7, and transgenic FZD3) was not determined, but it is possible that some of these could also have ciliary defects. For example, the cerebellar malformations observed in RIKEN 4930444A02 knockout mice show similarities to a number of developmental disorders, such as Joubert, Meckel-Gruber, and Bardet-Biedl syndromes, which involve mutations in cilia-related genes. Even though the direct relevance of mouse models to hydrocephalus in humans remains uncertain, the high prevalence of familial patterns of inheritance for congenital hydrocephalus in humans suggests that identification of genes responsible for development of hydrocephalus in mice may lead to the identification of homologous modifier genes and susceptibility alleles in humans. Also, characterization of mouse models can enhance understanding of important cell signaling and developmental pathways involved in the pathogenesis of hydrocephalus.
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Affiliation(s)
- P. Vogel
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
| | - R. W. Read
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
| | - G. M. Hansen
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
| | - B. J. Payne
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
| | - D. Small
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
| | - A. T. Sands
- Lexicon Pharmaceuticals, Inc, The Woodlands, Texas
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Defective Wnt-dependent cerebellar midline fusion in a mouse model of Joubert syndrome. Nat Med 2011; 17:726-31. [PMID: 21623382 PMCID: PMC3110639 DOI: 10.1038/nm.2380] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 04/19/2011] [Indexed: 01/15/2023]
Abstract
The ciliopathy Joubert syndrome is marked by cerebellar vermis hypoplasia, a phenotype for which the pathogenic mechanism is unclear1–3. In order to investigate Joubert syndrome pathogenesis, we have examined mice with mutated Ahi1, the first identified Joubert syndrome gene4,5. These mice exhibit cerebellar hypoplasia with a vermis/midline fusion defect early in development. This defect is concomitant with expansion of the roof plate and is also evident in a mouse mutant for another Joubert syndrome gene, Cep2906,7. Further, fetal magnetic resonance imaging (MRI) from human subjects with Joubert syndrome reveals a similar midline cleft suggesting parallel pathogenic mechanisms. Previous evidence has suggested a role for Jouberin (Jbn), the protein encoded by Ahi1, in canonical Wnt signaling8. Consistent with this, we found decreased Wnt reporter activity at the site of hemisphere fusion in the developing cerebellum of Ahi1 mutant mice. This decrease was accompanied by reduced proliferation at the site of fusion. Finally, treatment with lithium, a Wnt pathway agonist9, partially rescued this phenotype. Our findings implicate a defect in Wnt signaling in the cerebellar midline phenotype seen in Joubert syndrome, which can be overcome with Wnt stimulation.
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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: 194] [Impact Index Per Article: 14.9] [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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Rivero O, Reif A, Sanjuán J, Moltó MD, Kittel-Schneider S, Nájera C, Töpner T, Lesch KP. Impact of the AHI1 gene on the vulnerability to schizophrenia: a case-control association study. PLoS One 2010; 5:e12254. [PMID: 20805890 PMCID: PMC2923617 DOI: 10.1371/journal.pone.0012254] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 07/15/2010] [Indexed: 01/13/2023] Open
Abstract
Background The Abelson helper integration-1 (AHI1) gene is required for both cerebellar and cortical development in humans. While the accelerated evolution of AHI1 in the human lineage indicates a role in cognitive (dys)function, a linkage scan in large pedigrees identified AHI1 as a positional candidate for schizophrenia. To further investigate the contribution of AHI1 to the susceptibility of schizophrenia, we evaluated the effect of AHI1 variation on the vulnerability to psychosis in two samples from Spain and Germany. Methodology/Principal Findings 29 single-nucleotide polymorphisms (SNPs) located in a genomic region including the AHI1 gene were genotyped in two samples from Spain (280 patients with psychotic disorders; 348 controls) and Germany (247 patients with schizophrenic disorders; 360 controls). Allelic, genotypic and haplotype frequencies were compared between cases and controls in both samples separately, as well as in the combined sample. The effect of genotype on several psychopathological measures (BPRS, KGV, PANSS) assessed in a Spanish subsample was also evaluated. We found several significant associations in the Spanish sample. Particularly, rs7750586 and rs911507, both located upstream of the AHI1 coding region, were found to be associated with schizophrenia in the analysis of genotypic (p = 0.0033, and 0.031, respectively) and allelic frequencies (p = 0.001 in both cases). Moreover, several other risk and protective haplotypes were detected (0.006<p<0.036). Joint analysis also supported the association of rs7750586 and rs911507 with the risk for schizophrenia. The analysis of clinical measures also revealed an effect on symptom severity (minimum P value = 0.0037). Conclusions/Significance Our data support, in agreement with previous reports, an effect of AHI1 variation on the susceptibility to schizophrenia in central and southern European populations.
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Affiliation(s)
- Olga Rivero
- Unit of Molecular Psychiatry, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany.
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Lancaster MA, Gleeson JG. Cystic kidney disease: the role of Wnt signaling. Trends Mol Med 2010; 16:349-60. [PMID: 20576469 PMCID: PMC2919646 DOI: 10.1016/j.molmed.2010.05.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 02/07/2023]
Abstract
Wnt signaling encompasses a variety of signaling cascades that can be activated by secreted Wnt ligands. Two such pathways, the canonical or beta-catenin pathway and the planar cell polarity (PCP) pathway, have recently received attention for their roles in multiple cellular processes within the kidney. Both of these pathways are important for kidney development as well as homeostasis and injury repair. The disruption of either pathway can lead to cystic kidney disease, a class of genetic diseases that includes the most common hereditary life-threatening syndrome polycystic kidney disease (PKD). Recent evidence implicates canonical and noncanonical Wnt pathways in cyst formation and points to a remarkable role for developmental processes in the adult kidney.
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Affiliation(s)
- Madeline A Lancaster
- Biomedical Sciences Program, Howard Hughes Medical Institutes, Department of Neurosciences, University of California, San Diego, USA.
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33
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Transventricular delivery of Sonic hedgehog is essential to cerebellar ventricular zone development. Proc Natl Acad Sci U S A 2010; 107:8422-7. [PMID: 20400693 DOI: 10.1073/pnas.0911838107] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cerebellar neurons are generated from two germinal neuroepithelia: the ventricular zone (VZ) and rhombic lip. Signaling mechanisms that maintain the proliferative capacity of VZ resident progenitors remain elusive. We reveal that Sonic hedgehog (Shh) signaling is active in the cerebellar VZ and essential to radial glial cell proliferation and expansion of GABAergic interneurons. We demonstrate that the cerebellum is not the source of Shh that signals to the early VZ, and suggest a transventricular path for Shh ligand delivery. In agreement, we detected the presence of Shh protein in the circulating embryonic cerebrospinal fluid. This study identifies Shh as an essential proliferative signal for the cerebellar ventricular germinal zone, underscoring the potential contribution of VZ progenitors in the pathogenesis of cerebellar diseases associated with deregulated Shh signaling, and reveals a transventricular source of Shh in regulating neural development.
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Zaghloul NA, Katsanis N. Functional modules, mutational load and human genetic disease. Trends Genet 2010; 26:168-76. [PMID: 20226561 DOI: 10.1016/j.tig.2010.01.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 01/14/2010] [Accepted: 01/22/2010] [Indexed: 11/17/2022]
Abstract
The ability to generate a massive amount of sequencing and genotyping data is transforming the study of human genetic disorders. Driven by such innovation, it is likely that whole exome and whole-genome resequencing will replace regionally focused approaches for gene discovery and clinical testing in the next few years. However, this opportunity brings a significant interpretative challenge to assigning function and phenotypic variance to common and rare alleles. Understanding the effect of individual mutations in the context of the remaining genomic variation represents a major challenge to our interpretation of disease. Here, we discuss the challenges of assigning mutation functionality and, drawing from the examples of ciliopathies as well as cohesinopathies and channelopathies, discuss possibilities for the functional modularization of the human genome. Functional modularization in addition to the development of physiologically relevant assays to test allele functionality will accelerate our understanding of disease architecture and enable the use of genome-wide sequence data for disease diagnosis and phenotypic prediction in individuals.
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Affiliation(s)
- Norann A Zaghloul
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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35
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Baker K, Beales PL. Making sense of cilia in disease: the human ciliopathies. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2010; 151C:281-95. [PMID: 19876933 DOI: 10.1002/ajmg.c.30231] [Citation(s) in RCA: 245] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ubiquitous in nature, cilia and flagella comprise nearly identical structures with similar functions. The most obvious example of the latter is motility: driving movement of the organism or particle flow across the epithelial surface in fixed structures. In vertebrates, such motile cilia are evident in the respiratory epithelia, ependyma, and oviducts. For over a century, non-motile cilia have been observed on the surface of most vertebrate cells but until recently their function has eluded us. Gathering evidence now points to critical roles for the mono-cilium in sensing the extracellular environment, and perturbation of this function gives rise to a predictable panoply of clinical problems. We review the common clinical phenotypes associated with ciliopathies and interrogate Online Mendelian Inheritance in Man (OMIM) to compile a comprehensive list of putative disorders in which ciliary dysfunction may play a role.
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Affiliation(s)
- Kate Baker
- UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
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37
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Barkovich AJ, Millen KJ, Dobyns WB. A developmental and genetic classification for midbrain-hindbrain malformations. Brain 2009; 132:3199-230. [PMID: 19933510 PMCID: PMC2792369 DOI: 10.1093/brain/awp247] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 08/04/2009] [Accepted: 08/21/2009] [Indexed: 01/30/2023] Open
Abstract
Advances in neuroimaging, developmental biology and molecular genetics have increased the understanding of developmental disorders affecting the midbrain and hindbrain, both as isolated anomalies and as part of larger malformation syndromes. However, the understanding of these malformations and their relationships with other malformations, within the central nervous system and in the rest of the body, remains limited. A new classification system is proposed, based wherever possible, upon embryology and genetics. Proposed categories include: (i) malformations secondary to early anteroposterior and dorsoventral patterning defects, or to misspecification of mid-hindbrain germinal zones; (ii) malformations associated with later generalized developmental disorders that significantly affect the brainstem and cerebellum (and have a pathogenesis that is at least partly understood); (iii) localized brain malformations that significantly affect the brain stem and cerebellum (pathogenesis partly or largely understood, includes local proliferation, cell specification, migration and axonal guidance); and (iv) combined hypoplasia and atrophy of putative prenatal onset degenerative disorders. Pertinent embryology is discussed and the classification is justified. This classification will prove useful for both physicians who diagnose and treat patients with these disorders and for clinical scientists who wish to understand better the perturbations of developmental processes that produce them. Importantly, both the classification and its framework remain flexible enough to be easily modified when new embryologic processes are described or new malformations discovered.
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Affiliation(s)
- A James Barkovich
- Neuroradiology Room L371, University of California at San Francisco, 505 Parnassus Avenue, San Francisco, CA 94143-0628, USA.
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Abstract
Over the last 5 years, disorders of nonmotile cilia have come of age and their study has contributed immeasurably to our understanding of cell biology and human genetics. This review summarizes the main features of the ciliopathies, their underlying genetics, and the functions of the proteins involved. We describe some of the key findings in the field, including new animal models, the role of ciliopathy proteins in signaling pathways and development, and the unusual genetics of these diseases. We also discuss the therapeutic potential for these diseases and finally, discuss important future work that will extend our understanding of this fascinating organelle and its associated pathologies.
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Impaired Wnt-beta-catenin signaling disrupts adult renal homeostasis and leads to cystic kidney ciliopathy. Nat Med 2009; 15:1046-54. [PMID: 19718039 DOI: 10.1038/nm.2010] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 06/24/2009] [Indexed: 11/09/2022]
Abstract
Cystic kidney disease represents a major cause of end-stage renal disease, yet the molecular mechanisms of pathogenesis remain largely unclear. Recent emphasis has been placed on a potential role for canonical Wnt signaling, but investigation of this pathway in adult renal homeostasis is lacking. Here we provide evidence of a previously unidentified canonical Wnt activity in adult mammalian kidney homeostasis, the loss of which leads to cystic kidney disease. Loss of the Jouberin (Jbn) protein in mouse leads to the cystic kidney disease nephronophthisis, owing to an unexpected decrease in endogenous Wnt activity. Jbn interacts with and facilitates beta-catenin nuclear accumulation, resulting in positive modulation of downstream transcription. Finally, we show that Jbn is required in vivo for a Wnt response to injury and renal tubule repair, the absence of which triggers cystogenesis.
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40
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Hsiao YC, Tong ZJ, Westfall JE, Ault JG, Page-McCaw PS, Ferland RJ. Ahi1, whose human ortholog is mutated in Joubert syndrome, is required for Rab8a localization, ciliogenesis and vesicle trafficking. Hum Mol Genet 2009; 18:3926-41. [PMID: 19625297 DOI: 10.1093/hmg/ddp335] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The primary non-motile cilium, a membrane-ensheathed, microtubule-bundled organelle, extends from virtually all cells and is important for development. Normal functioning of the cilium requires proper axoneme assembly, membrane biogenesis and ciliary protein localization, in tight coordination with the intraflagellar transport system and vesicular trafficking. Disruptions at any level can induce severe alterations in cell function, giving rise to a myriad of human genetic diseases known as ciliopathies. Here we show that the Abelson helper integration site 1 (Ahi1) gene, whose human ortholog is mutated in Joubert syndrome, regulates cilium formation via its interaction with Rab8a, a small GTPase critical for polarized membrane trafficking. We find that the Ahi1 protein localizes to a single centriole, the mother centriole, which becomes the basal body of the primary cilium. In order to determine whether Ahi1 functions in ciliogenesis, loss of function analysis of Ahi1 was performed in cell culture models of ciliogenesis. Knockdown of Ahi1 expression by shRNAi in cells or targeted deletion of Ahi1 (Ahi1 knockout mouse) leads to impairments in ciliogenesis. In Ahi1-knockdown cells, Rab8a is destabilized and does not properly localize to the basal body. Since Rab8a is implicated in vesicular trafficking, we next examined this process in Ahi1-knockdown cells. Defects in the trafficking of endocytic vesicles from the plasma membrane to the Golgi and back to the plasma membrane were observed in Ahi1-knockdown cells. Overall, our data indicate that the distribution and functioning of Rab8a is regulated by Ahi1, not only affecting cilium formation, but also vesicle transport.
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Affiliation(s)
- Yi-Chun Hsiao
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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41
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Vaillant C, Monard D. SHH pathway and cerebellar development. THE CEREBELLUM 2009; 8:291-301. [PMID: 19224309 DOI: 10.1007/s12311-009-0094-8] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Accepted: 01/14/2009] [Indexed: 12/22/2022]
Abstract
The morphogenetic factor Sonic hedgehog (SHH) has been discovered as one of the masterplayers in cerebellar patterning and was subjected to intensive investigation during the last decade. During early postnatal development, this continuously secreted cholesterol-modified protein drives the expansion of the largest neuronal population of the brain, the granular cells. Moreover, it acts on Bergmann glia differentiation and would potentially affect Purkinje cells homeostasis at adult age. The cerebellar cortex constituted an ideal developmental model to dissect out the upstream mechanisms and downstream targets of this complex pathway. Its deep understanding discloses some of the mechanistic disorders underlying pediatric tumorigenesis, congenital ataxia, and mental retardation. Therapeutical use of its regulators has been consolidated on murine transgenic models and is now considered as a realistic human clinical application. Here, we will review the most recent advances made in the comprehensive understanding of SHH involvement in cerebellar development and pathology.
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Affiliation(s)
- Catherine Vaillant
- Developmental Genetics, Department Biomedicine, University of Basel, CH-4058 Basel, Switzerland
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42
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Meng XF, Luo Y, Xiao W, Li M, Shi J. Cloning and Characterization of the Promoter of the Human AHI1 Gene. Biochem Genet 2009; 47:427-38. [DOI: 10.1007/s10528-009-9232-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Accepted: 09/08/2008] [Indexed: 11/27/2022]
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Choh SA, Choh NA, Bhat SA, Jehangir M. MRI findings in Joubert syndrome. Indian J Pediatr 2009; 76:231-5. [PMID: 19129991 DOI: 10.1007/s12098-008-0232-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 01/28/2008] [Indexed: 11/25/2022]
Abstract
Joubert syndrome is a very rare autosomal recessive disorder with only 200 cases reported worldwide.Here we report 4 cases of this rare disorder with MRI findings.
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Affiliation(s)
- Suhil A Choh
- Department of Pediatrics & Neonatology SKIMS, Srinagar, India.
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44
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Rünker AE, Little GE, Suto F, Fujisawa H, Mitchell KJ. Semaphorin-6A controls guidance of corticospinal tract axons at multiple choice points. Neural Dev 2008; 3:34. [PMID: 19063725 PMCID: PMC2647909 DOI: 10.1186/1749-8104-3-34] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Accepted: 12/08/2008] [Indexed: 11/30/2022] Open
Abstract
Background The trajectory of corticospinal tract (CST) axons from cortex to spinal cord involves a succession of choice points, each of which is controlled by multiple guidance molecules. To assess the involvement of transmembrane semaphorins and their plexin receptors in the guidance of CST axons, we have examined this tract in mutants of Semaphorin-6A (Sema6A), Plexin-A2 (PlxnA2) and Plexin-A4 (PlxnA4). Results We describe defects in CST guidance in Sema6A mutants at choice points at the mid-hindbrain boundary (MHB) and in navigation through the pons that dramatically affect how many axons arrive to the hindbrain and spinal cord and result in hypoplasia of the CST. We also observe defects in guidance within the hindbrain where a proportion of axons aberrantly adopt a ventrolateral position and fail to decussate. This function in the hindbrain seems to be mediated by the known Sema6A receptor PlxnA4, which is expressed by CST axons. Guidance at the MHB, however, appears independent of this and of the other known receptor, PlxnA2, and may depend instead on Sema6A expression on CST axons themselves at embryonic stages. Conclusion These data identify Sema6A as a major contributor to the guidance of CST axons at multiple choice points. They highlight the active control of guidance at the MHB and also implicate the inferior olive as an important structure in the guidance of CST axons within the hindbrain. They also suggest that Sema6A, which is strongly expressed by oligodendrocytes, may affect CST regeneration in adults.
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Affiliation(s)
- Annette E Rünker
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland.
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45
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Sheng G, Xu X, Lin YF, Wang CE, Rong J, Cheng D, Peng J, Jiang X, Li SH, Li XJ. Huntingtin-associated protein 1 interacts with Ahi1 to regulate cerebellar and brainstem development in mice. J Clin Invest 2008; 118:2785-95. [PMID: 18636121 DOI: 10.1172/jci35339] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Accepted: 05/28/2008] [Indexed: 01/10/2023] Open
Abstract
Joubert syndrome is an autosomal recessive disorder characterized by congenital malformation of the cerebellum and brainstem, with abnormal decussation in the brain. Mutations in the Abelson helper integration site 1 gene, which encodes the protein AHI1, have been shown to cause Joubert syndrome. In this study, we found that mouse Ahi1 formed a stable complex with huntingtin-associated protein 1 (Hap1), which is critical for neonatal development and involved in intracellular trafficking. Hap1-knockout mice showed significantly reduced Ahi1 levels, defective cerebellar development, and abnormal axonal decussation. Suppression of Ahi1 also decreased the level of Hap1; and truncated Ahi1, which corresponds to the mutations in Joubert syndrome, inhibited neurite outgrowth in neuronal culture. Reducing Hap1 expression suppressed the level and internalization of TrkB, a neurotrophic factor receptor that mediates neurogenesis and neuronal differentiation, which led to decreased TrkB signaling. These findings provide insight into the pathogenesis of Joubert syndrome and demonstrate the critical role of the Ahi1-Hap1 complex in early brain development.
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Affiliation(s)
- Guoqing Sheng
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
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46
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Lavin MF, Gueven N, Grattan-Smith P. Defective responses to DNA single- and double-strand breaks in spinocerebellar ataxia. DNA Repair (Amst) 2008; 7:1061-76. [PMID: 18467193 DOI: 10.1016/j.dnarep.2008.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Failure to maintain the integrity of DNA/chromatin can result in genome instability and an increased risk of cancer. The description of a number of human genetic disorders characterised not only by cancer predisposition but by a broader phenotype including neurodegeneration suggests that maintaining genome stability is also important for preserving post-mitotic neurons. The identification of genes associated with other neurodegenerative disorders provides further evidence for the importance of DNA damage response and DNA repair genes in protecting against neurodegeneration. This theme is further developed in this review.
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Affiliation(s)
- Martin F Lavin
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia.
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47
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Ozyurek H, Kayacik OE, Gungor O, Karagoz F. Rare association of Hirschsprung's disease and Joubert syndrome. Eur J Pediatr 2008; 167:475-7. [PMID: 17516083 DOI: 10.1007/s00431-007-0504-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 04/23/2007] [Indexed: 11/29/2022]
Abstract
We present the case of an 18-month-old boy with Hirschsprung's disease who had psychomotor retardation. His clinical and radiological findings were consistent with Joubert syndrome. The patient was the second case to show the association between Hirschsprung's disease and Joubert syndrome in the literature. As in our case, association of these entities by chance seems to be unlikely. Genetic analysis of new Joubert syndrome and Hirschsprung's disease patients may identify the candidate genes.
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Affiliation(s)
- Hamit Ozyurek
- Department of Pediatrics, Faculty of Medicine, Ondokuz Mayis University, 55139, Kurupelit, Samsun, Turkey.
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Spassky N, Han YG, Aguilar A, Strehl L, Besse L, Laclef C, Ros MR, Garcia-Verdugo JM, Alvarez-Buylla A. Primary cilia are required for cerebellar development and Shh-dependent expansion of progenitor pool. Dev Biol 2008; 317:246-59. [PMID: 18353302 DOI: 10.1016/j.ydbio.2008.02.026] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Revised: 02/12/2008] [Accepted: 02/12/2008] [Indexed: 10/22/2022]
Abstract
Cerebellar granule cell precursors (GCPs), which give rise to the most abundant neuronal type in the mammalian brain, arise from a restricted pool of primary progenitors in the rhombic lip (RL). Sonic hedgehog (Shh) secreted by developing Purkinje cells is essential for the expansion of GCPs and for cerebellar morphogenesis. Recent studies have shown that the primary cilium concentrates components of Shh signaling and that this structure is required for Shh signaling. GCPs have a primary cilium on their surface [Del Cerro, M.P., Snider, R.S. (1972). Studies on the developing cerebellum. II. The ultrastructure of the external granular layer. J Comp Neurol 144, 131-64.]. Here, we show that 1) this cilium can be conditionally ablated by crossing Kif3a(fl/-) mice with hGFAP-Cre mice, 2) removal of Kif3a from GCPs disrupts cerebellar development, and 3) these defects are due to a drastic reduction in Shh-dependent expansion of GCPs. A similar phenotype is observed when Smoothened (Smo), an essential transducer of Shh signaling, is removed from the same population of GCPs. Interestingly, Kif3a-Smo double conditional mutants show that Kif3a is epistatic to Smo. This work shows that Kif3a is essential for Shh-dependent expansion of cerebellar progenitors. Dysfunctional cilia are associated with diverse human disorders including Bardet-Biedl and Joubert syndromes. Cerebellar abnormalities observed in these patients could be explained by defects in Shh-induced GCP expansion.
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Affiliation(s)
- N Spassky
- Université Pierre and Marie Curie, IFR des Neurosciences, INSERM U711, Hôpital Pitié-Salpêtrière, Paris, F-75013, France.
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Abstract
Primary (nonmotile) cilia are currently enjoying a renaissance in light of novel ascribed functions ranging from mechanosensory to signal transduction. Their importance for key developmental pathways such as Sonic Hedgehog (Shh) and Wnt is beginning to emerge. The function of nodal cilia, for example, is vital for breaking early embryonic symmetry, Shh signaling is important for tissue morphogenesis and successful Wnt signaling for organ growth and differentiation. When ciliary function is perturbed, photoreceptors may die, kidney tubules develop cysts, limb digits multiply and brains form improperly. The etiology of several uncommon disorders has recently been associated with cilia dysfunction. The causative genes are often similar and their cognate proteins certainly share cellular locations and/or pathways. Animal models of ciliary gene ablation such as Ift88, Kif3a, and Bbs have been invaluable for understanding the broad function of the cilium. Herein, we describe the wealth of information derived from the study of the ciliopathies and their animal models.
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Valente EM, Brancati F, Dallapiccola B. Genotypes and phenotypes of Joubert syndrome and related disorders. Eur J Med Genet 2008; 51:1-23. [PMID: 18164675 DOI: 10.1016/j.ejmg.2007.11.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 11/07/2007] [Indexed: 01/05/2023]
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