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Pinho-Correia LM, Prokop A. Maintaining essential microtubule bundles in meter-long axons: a role for local tubulin biogenesis? Brain Res Bull 2023; 193:131-145. [PMID: 36535305 DOI: 10.1016/j.brainresbull.2022.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 12/12/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
Axons are the narrow, up-to-meter long cellular processes of neurons that form the biological cables wiring our nervous system. Most axons must survive for an organism's lifetime, i.e. up to a century in humans. Axonal maintenance depends on loose bundles of microtubules that run without interruption all along axons. The continued turn-over and the extension of microtubule bundles during developmental, regenerative or plastic growth requires the availability of α/β-tubulin heterodimers up to a meter away from the cell body. The underlying regulation in axons is poorly understood and hardly features in past and contemporary research. Here we discuss potential mechanisms, particularly focussing on the possibility of local tubulin biogenesis in axons. Current knowledge might suggest that local translation of tubulin takes place in axons, but far less is known about the post-translational machinery of tubulin biogenesis involving three chaperone complexes: prefoldin, CCT and TBC. We discuss functional understanding of these chaperones from a range of model organisms including yeast, plants, flies and mice, and explain what is known from human diseases. Microtubules across species depend on these chaperones, and they are clearly required in the nervous system. However, most chaperones display a high degree of functional pleiotropy, partly through independent functions of individual subunits outside their complexes, thus posing a challenge to experimental studies. Notably, we found hardly any studies that investigate their presence and function particularly in axons, thus highlighting an important gap in our understanding of axon biology and pathology.
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Affiliation(s)
- Liliana Maria Pinho-Correia
- The University of Manchester, Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, Manchester, UK
| | - Andreas Prokop
- The University of Manchester, Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, Manchester, UK.
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2
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Bieniussa L, Kahraman B, Skornicka J, Schulte A, Voelker J, Jablonka S, Hagen R, Rak K. Pegylated Insulin-Like Growth Factor 1 attenuates Hair Cell Loss and promotes Presynaptic Maintenance of Medial Olivocochlear Cholinergic Fibers in the Cochlea of the Progressive Motor Neuropathy Mouse. Front Neurol 2022; 13:885026. [PMID: 35720065 PMCID: PMC9203726 DOI: 10.3389/fneur.2022.885026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
The progressive motor neuropathy (PMN) mouse is a model of an inherited motor neuropathy disease with progressive neurodegeneration. Axon degeneration associates with homozygous mutations of the TBCE gene encoding the tubulin chaperone E protein. TBCE is responsible for the correct dimerization of alpha and beta-tubulin. Strikingly, the PMN mouse also develops a progressive hearing loss after normal hearing onset, characterized by degeneration of the auditory nerve and outer hair cell (OHC) loss. However, the development of this neuronal and cochlear pathology is not fully understood yet. Previous studies with pegylated insulin-like growth factor 1 (peg-IGF-1) treatment in this mouse model have been shown to expand lifespan, weight, muscle strength, and motor coordination. Accordingly, peg-IGF-1 was evaluated for an otoprotective effect. We investigated the effect of peg-IGF-1 on the auditory system by treatment starting at postnatal day 15 (p15). Histological analysis revealed positive effects on OHC synapses of medial olivocochlear (MOC) neuronal fibers and a short-term attenuation of OHC loss. Peg-IGF-1 was able to conditionally restore the disorganization of OHC synapses and maintain the provision of cholinergic acetyltransferase in presynapses. To assess auditory function, frequency-specific auditory brainstem responses and distortion product otoacoustic emissions were recorded in animals on p21 and p28. However, despite the positive effect on MOC fibers and OHC, no restoration of hearing could be achieved. The present work demonstrates that the synaptic pathology of efferent MOC fibers in PMN mice represents a particular form of “efferent auditory neuropathy.” Peg-IGF-1 showed an otoprotective effect by preventing the degeneration of OHCs and efferent synapses. However, enhanced efforts are needed to optimize the treatment to obtain detectable improvements in hearing performances.
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Affiliation(s)
- Linda Bieniussa
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Germany
| | - Baran Kahraman
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Germany
| | - Johannes Skornicka
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Germany
| | - Annemarie Schulte
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Johannes Voelker
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Germany
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University of Würzburg, Würzburg, Germany
| | - Rudolf Hagen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Germany
| | - Kristen Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Germany
- *Correspondence: Kristen Rak
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3
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Kulminski AM, Loiko E, Loika Y, Culminskaya I. Pleiotropic predisposition to Alzheimer's disease and educational attainment: insights from the summary statistics analysis. GeroScience 2022; 44:265-280. [PMID: 34743297 PMCID: PMC8572080 DOI: 10.1007/s11357-021-00484-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 10/28/2021] [Indexed: 12/25/2022] Open
Abstract
Epidemiological studies report beneficial associations of higher educational attainment (EDU) with Alzheimer's disease (AD). Prior genome-wide association studies (GWAS) also reported variants associated with AD and EDU separately. The analysis of pleiotropic associations with these phenotypes may shed light on EDU-related protection against AD. We performed pleiotropic meta-analyses using Fisher's method and omnibus test applied to summary statistics for single nucleotide polymorphisms (SNPs) associated with AD and EDU in large-scale univariate GWAS at suggestive-effect (5 × 10-8 < p < 0.1) and genome-wide (p ≤ 5 × 10-8) significance levels. We report 53 SNPs that attained p ≤ 5 × 10-8 at least in one of the pleiotropic meta-analyses and were reported in the univariate GWAS at 5 × 10-8 < p < 0.1. Of them, there were 46 pleiotropic SNPs according to Fisher's method. Additionally, Fisher's method identified 25 of 206 SNPs with pleiotropic effects, which attained p ≤ 5 × 10-8 in the univariate GWAS. We showed that a large fraction of the pleiotropic associations was affected by a counterintuitive phenomenon of antagonistic genetic heterogeneity, which explains the increase, rather than decrease, of the significance of the pleiotropic associations in the omnibus test. Functional enrichment analysis showed that apart from cancers, gene set harboring the non-pleiotropic SNPs was characterized by late-onset AD and neurodevelopmental disorders. The pleiotropic gene set was characterized by a broad spectrum of progressive neurological and neuromuscular diseases and immune-mediated conditions, including progressive motor neuropathy, multiple sclerosis, Parkinson's disease, and severe AD. Our results suggest that disentangling genes harboring variants with and without pleiotropic associations with AD and EDU is promising for dissecting heterogeneity in biological mechanisms of AD.
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Affiliation(s)
- Alexander M Kulminski
- Biodemography of Aging Research Unit, Social Science Research Institute, Duke University, Durham, NC, 27708-0408, USA.
| | - Elena Loiko
- Biodemography of Aging Research Unit, Social Science Research Institute, Duke University, Durham, NC, 27708-0408, USA
| | - Yury Loika
- Biodemography of Aging Research Unit, Social Science Research Institute, Duke University, Durham, NC, 27708-0408, USA
| | - Irina Culminskaya
- Biodemography of Aging Research Unit, Social Science Research Institute, Duke University, Durham, NC, 27708-0408, USA
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David O, Agur R, Novoa R, Shaki D, Walker D, Carmon L, Eskin-Schwartz M, Birk OS, Ling G, Schreiber R, Loewenthal N, Haim A, Hershkovitz E. Hypoparathyroidism-retardation-dysmorphism syndrome-Clinical insights from a large longitudinal cohort in a single medical center. Front Pediatr 2022; 10:916679. [PMID: 35935360 PMCID: PMC9352926 DOI: 10.3389/fped.2022.916679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 06/28/2022] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Hypoparathyroidism, retardation, and dysmorphism (HRD) Syndrome is a rare disease composed of hypoparathyroidism, retardation of both growth and development, and distinctive dysmorphic features. Here, we describe the long-term morbidity and mortality in a large cohort of HRD patients and suggest recommendations for follow up and treatment. METHODS Medical records of 63 HRD syndrome patients who were followed at Soroka Medical Center during 1989-2019 were reviewed retrospectively. Information regarding demographics, medical complications, laboratory findings, and imaging studies was collected. RESULTS The mortality rate was 52%. The main causes of death were infectious diseases including pneumonia, septic shock, and meningitis. Multiple comorbidities were found including brain anomalies in 90% of examined patients (basal ganglia calcifications, tightening of corpus callosum, Chiari malformation, hydrocephalous, and brain atrophy), seizures in 62%, nephrocalcinosis and/or nephrolithiasis in 47%, multiple eye anomalies were recorded in 40%, bowel obstructions in 9.5%, and variable expression of both conductive and senso-neural hearing loss was documented in 9.5%. CONCLUSION HRD is a severe multisystem disease. Active surveillance is indicated to prevent and treat complications associated with this rare syndrome.
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Affiliation(s)
- Odeya David
- Pediatric Endocrinology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Rotem Agur
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Rosa Novoa
- Diagnostic Radiology Department, Soroka University Medical Center, Beer Sheva, Israel
| | - David Shaki
- Pediatric Endocrinology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dganit Walker
- Pediatric Endocrinology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel
| | - Lior Carmon
- Pediatric Endocrinology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Marina Eskin-Schwartz
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Morris Kahn Laboratory of Human Genetics, National Center for Rare Diseases, Faculty of Health Sciences, National Institute for Biotechnology in the Negev, Genetics Institute at Soroka University Medical Center, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Ohad S Birk
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Morris Kahn Laboratory of Human Genetics, National Center for Rare Diseases, Faculty of Health Sciences, National Institute for Biotechnology in the Negev, Genetics Institute at Soroka University Medical Center, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Galina Ling
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Pediatric Gastroenterology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel
| | - Ruth Schreiber
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Pediatric Nephrology Unit, Soroka University Medical Center, Beer Sheva, Israel
| | - Neta Loewenthal
- Pediatric Endocrinology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Alon Haim
- Pediatric Endocrinology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Eli Hershkovitz
- Pediatric Endocrinology Unit, Saban Pediatric Medical Center for Israel, Soroka University Medical Center, Beer Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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5
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Battini R, Milone R, Aiello C, Astrea G, Sferra A, Pasquariello R, Cioni G, Bertini E. Broadening the spectrum phenotype of TBCE-related neuron neurodegeneration. Brain Dev 2021; 43:939-944. [PMID: 34134906 DOI: 10.1016/j.braindev.2021.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 05/09/2021] [Accepted: 05/30/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Severe loss of TBCE function has been related to two well-known dysmorphic syndromes, while TBCE hypomorphic variants have been linked to neurodegenerative conditions due to perturbed microtubule dynamics and homeostasis, with signs of central and peripheral nervous system involvement. METHOD We report on an Italian female originating from Southern Italy who presented early-onset regression and neurodegeneration, with neurological features of tetraparesis and signs of peripheral nervous system involvement. Her brain MRI revealed white matter involvement. RESULTS Analyzing all known hypomyelination leukodystrophies related genes, two mutations in TBCE (NM_001079515) were detected: the missense variant c.464 T > A; p. (Ile155Asn) and the frameshift variant c.924del; p. (Leu309Ter), in compound heterozygosity, already reported in the literature in patients coming from the same geographical area. The clinical phenotype of the proposita was more severe and with an earlier onset than the majority of the patients reported so far. CONCLUSIONS Next Generation Sequencing is becoming increasingly necessary to assess unusual phenotypes, with the opportunity to establish prognosis and disease mechanisms, and facilitating differential diagnosis.
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Affiliation(s)
- Roberta Battini
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy; Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
| | - Roberta Milone
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
| | - Chiara Aiello
- Unit of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Ospedale Bambino Gesù Research Children's Hospital, IRCCS, Rome, Italy
| | - Guja Astrea
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
| | - Antonella Sferra
- Unit of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Ospedale Bambino Gesù Research Children's Hospital, IRCCS, Rome, Italy
| | - Rosa Pasquariello
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy
| | - Giovanni Cioni
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, Pisa, Italy; Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Enrico Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Ospedale Bambino Gesù Research Children's Hospital, IRCCS, Rome, Italy
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6
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Lauri A, Fasano G, Venditti M, Dallapiccola B, Tartaglia M. In vivo Functional Genomics for Undiagnosed Patients: The Impact of Small GTPases Signaling Dysregulation at Pan-Embryo Developmental Scale. Front Cell Dev Biol 2021; 9:642235. [PMID: 34124035 PMCID: PMC8194860 DOI: 10.3389/fcell.2021.642235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/12/2021] [Indexed: 12/24/2022] Open
Abstract
While individually rare, disorders affecting development collectively represent a substantial clinical, psychological, and socioeconomic burden to patients, families, and society. Insights into the molecular mechanisms underlying these disorders are required to speed up diagnosis, improve counseling, and optimize management toward targeted therapies. Genome sequencing is now unveiling previously unexplored genetic variations in undiagnosed patients, which require functional validation and mechanistic understanding, particularly when dealing with novel nosologic entities. Functional perturbations of key regulators acting on signals' intersections of evolutionarily conserved pathways in these pathological conditions hinder the fine balance between various developmental inputs governing morphogenesis and homeostasis. However, the distinct mechanisms by which these hubs orchestrate pathways to ensure the developmental coordinates are poorly understood. Integrative functional genomics implementing quantitative in vivo models of embryogenesis with subcellular precision in whole organisms contribute to answering these questions. Here, we review the current knowledge on genes and mechanisms critically involved in developmental syndromes and pediatric cancers, revealed by genomic sequencing and in vivo models such as insects, worms and fish. We focus on the monomeric GTPases of the RAS superfamily and their influence on crucial developmental signals and processes. We next discuss the effectiveness of exponentially growing functional assays employing tractable models to identify regulatory crossroads. Unprecedented sophistications are now possible in zebrafish, i.e., genome editing with single-nucleotide precision, nanoimaging, highly resolved recording of multiple small molecules activity, and simultaneous monitoring of brain circuits and complex behavioral response. These assets permit accurate real-time reporting of dynamic small GTPases-controlled processes in entire organisms, owning the potential to tackle rare disease mechanisms.
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Affiliation(s)
- Antonella Lauri
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | | | | | | | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
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7
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Nolasco S, Bellido J, Serna M, Carmona B, Soares H, Zabala JC. Colchicine Blocks Tubulin Heterodimer Recycling by Tubulin Cofactors TBCA, TBCB, and TBCE. Front Cell Dev Biol 2021; 9:656273. [PMID: 33968934 PMCID: PMC8100514 DOI: 10.3389/fcell.2021.656273] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 03/29/2021] [Indexed: 11/17/2022] Open
Abstract
Colchicine has been used to treat gout and, more recently, to effectively prevent autoinflammatory diseases and both primary and recurrent episodes of pericarditis. The anti-inflammatory action of colchicine seems to result from irreversible inhibition of tubulin polymerization and microtubule (MT) assembly by binding to the tubulin heterodimer, avoiding the signal transduction required to the activation of the entire NLRP3 inflammasome. Emerging results show that the MT network is a potential regulator of cardiac mechanics. Here, we investigated how colchicine impacts in tubulin folding cofactors TBCA, TBCB, and TBCE activities. We show that TBCA is abundant in mouse heart insoluble protein extracts. Also, a decrease of the TBCA/β-tubulin complex followed by an increase of free TBCA is observed in human cells treated with colchicine. The presence of free TBCA is not observed in cells treated with other anti-mitotic agents such as nocodazole or cold shock, neither after translation inhibition by cycloheximide. In vitro assays show that colchicine inhibits tubulin heterodimer dissociation by TBCE/TBCB, probably by interfering with interactions of TBCE with tubulin dimers, leading to free TBCA. Manipulation of TBCA levels, either by RNAi or overexpression results in decreased levels of tubulin heterodimers. Together, these data strongly suggest that TBCA is mainly receiving β-tubulin from the dissociation of pre-existing heterodimers instead of newly synthesized tubulins. The TBCE/TBCB+TBCA system is crucial for controlling the critical concentration of free tubulin heterodimers and MT dynamics in the cells by recycling the tubulin heterodimers. It is conceivable that colchicine affects tubulin heterodimer recycling through the TBCE/TBCB+TBCA system producing the known benefits in the treatment of pericardium inflammation.
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Affiliation(s)
- Sofia Nolasco
- Faculdade de Medicina Veterinária, CIISA - Centro de Investigação Interdisciplinar em Sanidade Animal, Universidade de Lisboa, Lisbon, Portugal.,Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Lisbon, Portugal
| | - Javier Bellido
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Marina Serna
- Spanish National Cancer Research Center, CNIO, Madrid, Spain
| | - Bruno Carmona
- Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Lisbon, Portugal.,Centro de Química Estrutural - Faculdade de Ciências da Universidade de Lisboa, Lisbon, Portugal
| | - Helena Soares
- Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Lisbon, Portugal.,Centro de Química Estrutural - Faculdade de Ciências da Universidade de Lisboa, Lisbon, Portugal
| | - Juan Carlos Zabala
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
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8
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Métivier M, Gallaud E, Thomas A, Pascal A, Gagné JP, Poirier GG, Chrétien D, Gibeaux R, Richard-Parpaillon L, Benaud C, Giet R. Drosophila Tubulin-Specific Chaperone E Recruits Tubulin around Chromatin to Promote Mitotic Spindle Assembly. Curr Biol 2021; 31:684-695.e6. [PMID: 33259793 DOI: 10.1016/j.cub.2020.11.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 09/29/2020] [Accepted: 11/03/2020] [Indexed: 12/31/2022]
Abstract
Proper assembly of mitotic spindles requires microtubule nucleation not only at the centrosomes but also around chromatin. In this study, we found that the Drosophila tubulin-specific chaperone dTBCE is required for the enrichment of tubulin in the nuclear space after nuclear envelope breakdown and for subsequent promotion of spindle microtubule nucleation. These events depend on the CAP-Gly motif found in dTBCE and are regulated by Ran and lamin proteins. Our data suggest that during early mitosis, dTBCE and nuclear pore proteins become enriched in the nucleus, where they interact with the Ran GTPase to promote dynamic tubulin enrichment. We propose that this novel mechanism enhances microtubule nucleation around chromatin, thereby facilitating mitotic spindle assembly.
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Affiliation(s)
- Mathieu Métivier
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Emmanuel Gallaud
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Alexandre Thomas
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Aude Pascal
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Jean-Philippe Gagné
- Centre de Recherche du Centre Hospitalier Universitaire de Québec - Pavillon CHUL, Université Laval, Québec City, QC, Canada
| | - Guy G Poirier
- Centre de Recherche du Centre Hospitalier Universitaire de Québec - Pavillon CHUL, Université Laval, Québec City, QC, Canada
| | - Denis Chrétien
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Romain Gibeaux
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Laurent Richard-Parpaillon
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Christelle Benaud
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Régis Giet
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France.
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9
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Golgi Fragmentation in Neurodegenerative Diseases: Is There a Common Cause? Cells 2019; 8:cells8070748. [PMID: 31331075 PMCID: PMC6679019 DOI: 10.3390/cells8070748] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/17/2019] [Accepted: 07/17/2019] [Indexed: 02/06/2023] Open
Abstract
In most mammalian cells, the Golgi complex forms a continuous ribbon. In neurodegenerative diseases, the Golgi ribbon of a specific group of neurons is typically broken into isolated elements, a very early event which happens before clinical and other pathological symptoms become evident. It is not known whether this phenomenon is caused by mechanisms associated with cell death or if, conversely, it triggers apoptosis. When the phenomenon was studied in diseases such as Parkinson’s and Alzheimer’s or amyotrophic lateral sclerosis, it was attributed to a variety of causes, including the presence of cytoplasmatic protein aggregates, malfunctioning of intracellular traffic and/or alterations in the cytoskeleton. In the present review, we summarize the current findings related to these and other neurodegenerative diseases and try to search for clues on putative common causes.
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10
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Abstract
During the process of neurogenesis, the stem cell committed to the neuronal cell fate starts a series of molecular and morphological changes. The understanding of the physio-pathology of mechanisms controlling the molecular and morphological changes occurring during neuronal differentiation is fundamental to the development of effective therapies for many neurologic diseases. Unfortunately, our knowledge of the biological events occurring in the cell during neuronal differentiation is still poor. In this study, we focus preliminarily on the relevance of the cytoskeletal rearrangements, which earlier drive the morphology of the neuronal precursors, and later the migrating/mature neurons. In fact, neuritogenesis, neurite branching, outgrowth and retraction are seminal to the development of a fully functional nervous system. With this in mind, we highlight the importance of iPSC technology to study the processes of cytoskeletal-driven morphological changes during neuronal differentiation.
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11
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Plasticity Related Gene 3 (PRG3) overcomes myelin-associated growth inhibition and promotes functional recovery after spinal cord injury. Aging (Albany NY) 2017; 8:2463-2487. [PMID: 27744421 PMCID: PMC5115901 DOI: 10.18632/aging.101066] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/25/2016] [Indexed: 12/14/2022]
Abstract
The Plasticity Related Gene family covers five, brain-specific, transmembrane proteins (PRG1-5, also termed LPPR1-5) that operate in neuronal plasticity during development, aging and brain trauma. Here we investigated the role of the PRG family on axonal and filopodia outgrowth. Comparative analysis revealed the strongest outgrowth induced by PRG3 (LPPR1). During development, PRG3 is ubiquitously located at the tip of neuronal processes and at the plasma membrane and declines with age. In utero electroporation of PRG3 induced dendritic protrusions and accelerated spine formations in cortical pyramidal neurons. The neurite growth promoting activity of PRG3 requires RasGRF1 (RasGEF1/Cdc25) mediated downstream signaling. Moreover, in axon collapse assays, PRG3-induced neurites resisted growth inhibitors such as myelin, Nogo-A (Reticulon/RTN-4), thrombin and LPA and impeded the RhoA-Rock-PIP5K induced neurite repulsion. Transgenic adult mice with constitutive PRG3 expression displayed strong axonal sprouting distal to a spinal cord lesion. Moreover, fostered PRG3 expression promoted complex motor-behavioral recovery compared to wild type controls as revealed in the Schnell swim test (SST). Thus, PRG3 emerges as a developmental RasGRF1-dependent conductor of filopodia formation and axonal growth enhancer. PRG3-induced neurites resist brain injury-associated outgrowth inhibitors and contribute to functional recovery after spinal cord lesions. Here, we provide evidence that PRG3 operates as an essential neuronal growth promoter in the nervous system. Maintaining PRG3 expression in aging brain may turn back the developmental clock for neuronal regeneration and plasticity.
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Giri A, Hartmann KE, Aldrich MC, Ward RM, Wu JM, Park AJ, Graff M, Qi L, Nassir R, Wallace RB, O'Sullivan MJ, North KE, Velez Edwards DR, Edwards TL. Admixture mapping of pelvic organ prolapse in African Americans from the Women's Health Initiative Hormone Therapy trial. PLoS One 2017; 12:e0178839. [PMID: 28582460 PMCID: PMC5459562 DOI: 10.1371/journal.pone.0178839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 05/19/2017] [Indexed: 12/27/2022] Open
Abstract
Evidence suggests European American (EA) women have two- to five-fold increased odds of having pelvic organ prolapse (POP) when compared with African American (AA) women. However, the role of genetic ancestry in relation to POP risk is not clear. Here we evaluate the association between genetic ancestry and POP in AA women from the Women’s Health Initiative Hormone Therapy trial. Women with grade 1 or higher classification, and grade 2 or higher classification for uterine prolapse, cystocele or rectocele at baseline or during follow-up were considered to have any POP (N = 805) and moderate/severe POP (N = 156), respectively. Women with at least two pelvic exams with no indication for POP served as controls (N = 344). We performed case-only, and case-control admixture-mapping analyses using multiple logistic regression while adjusting for age, BMI, parity and global ancestry. We evaluated the association between global ancestry and POP using multiple logistic regression. European ancestry at the individual level was not associated with POP risk. Case-only and case-control local ancestry analyses identified two ancestry-specific loci that may be associated with POP. One locus (Chromosome 15q26.2) achieved empirically-estimated statistical significance and was associated with decreased POP odds (considering grade ≥2 POP) with each unit increase in European ancestry (OR: 0.35; 95% CI: 0.30, 0.57; p-value = 1.48x10-5). This region includes RGMA, a potent regulator of the BMP family of genes. The second locus (Chromosome 1q42.1-q42.3) was associated with increased POP odds with each unit increase in European ancestry (Odds ratio [OR]: 1.69; 95% confidence interval [CI]: 1.28, 2.22; p-value = 1.93x10-4). Although this region did not reach statistical significance after considering multiple comparisons, it includes potentially relevant genes including TBCE, and ACTA1. Unique non-overlapping European and African ancestry-specific susceptibility loci may be associated with increased POP risk.
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Affiliation(s)
- Ayush Giri
- Vanderbilt Epidemiology Center, Institute for Medicine and Public Health, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Katherine E. Hartmann
- Vanderbilt Epidemiology Center, Institute for Medicine and Public Health, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Melinda C. Aldrich
- Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Thoracic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Renee M. Ward
- Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jennifer M. Wu
- Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Amy J. Park
- Department of Obstetrics and Gynecology, Georgetown University School of Medicine, Washington, District of Columbia, United States of America
| | - Mariaelisa Graff
- Department of Epidemiology, Gillings School of Global Public health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Lihong Qi
- Division of Biostatistics, Department of Public Health Sciences, School of Medicine, University of California, Davis, Davis, California, United States of America
| | - Rami Nassir
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, California, United States of America
- Department of Internal Medicine, University of California, Davis, Davis, California, United States of America
| | - Robert B. Wallace
- Department of Epidemiology, University of Iowa College of Public Health, Iowa City, Iowa, United States of America
| | - Mary J. O'Sullivan
- Department of Obstetrics and Gynecology, Miller School of Medicine, Miami, Florida, United States of America
| | - Kari E. North
- Department of Epidemiology, Gillings School of Global Public health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Digna R. Velez Edwards
- Vanderbilt Epidemiology Center, Institute for Medicine and Public Health, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Todd L. Edwards
- Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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Schäfer MK, Bellouze S, Jacquier A, Schaller S, Richard L, Mathis S, Vallat JM, Haase G. Sensory neuropathy in progressive motor neuronopathy (pmn) mice is associated with defects in microtubule polymerization and axonal transport. Brain Pathol 2016; 27:459-471. [PMID: 27488538 DOI: 10.1111/bpa.12422] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 07/25/2016] [Indexed: 12/11/2022] Open
Abstract
Motor neuron diseases such as amyotrophic lateral sclerosis (ALS) are now recognized as multi-system disorders also involving various non-motor neuronal cell types. The precise extent and mechanistic basis of non-motor neuron damage in human ALS and ALS animal models remain however unclear. To address this, we here studied progressive motor neuronopathy (pmn) mice carrying a missense loss-of-function mutation in tubulin binding cofactor E (TBCE). These mice manifest a particularly aggressive form of motor axon dying back and display a microtubule loss, similar to that induced by human ALS-linked TUBA4A mutations. Using whole nerve confocal imaging of pmn × thy1.2-YFP16 fluorescent reporter mice and electron microscopy, we demonstrate axonal discontinuities, bead-like spheroids and ovoids in pmn suralis nerves indicating prominent sensory neuropathy. The axonal alterations qualitatively resemble those in phrenic motor nerves but do not culminate in the loss of myelinated fibers. We further show that the pmn mutation decreases the level of TBCE, impedes microtubule polymerization in dorsal root ganglion (DRG) neurons and causes progressive loss of microtubules in large and small caliber suralis axons. Live imaging of axonal transport using GFP-tagged tetanus toxin C-fragment (GFP-TTC) demonstrates defects in microtubule-based transport in pmn DRG neurons, providing a potential explanation for the axonal alterations in sensory nerves. This study unravels sensory neuropathy as a pathological feature of mouse pmn, and discusses the potential contribution of cytoskeletal defects to sensory neuropathy in human motor neuron disease.
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Affiliation(s)
- Michael K Schäfer
- Department of Anesthesiology and Research Center Translational Neurosciences, University Medical Center of the Johannes Gutenberg-University Mainz, Germany
| | - Sarah Bellouze
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université UMR 7289, Marseille, France
| | - Arnaud Jacquier
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université UMR 7289, Marseille, France
| | - Sébastien Schaller
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université UMR 7289, Marseille, France
| | - Laurence Richard
- Laboratoire de Neurologie, Centre de référence national "Neuropathies périphériques rares", Centre Hospitalo-Universitaire (CHU), Limoges, France
| | - Stéphane Mathis
- Department of Neurology, Centre Hospitalo-Universitaire (CHU) Poitiers, University of Poitiers, Poitiers, France
| | - Jean-Michel Vallat
- Laboratoire de Neurologie, Centre de référence national "Neuropathies périphériques rares", Centre Hospitalo-Universitaire (CHU), Limoges, France
| | - Georg Haase
- Institut de Neurosciences de la Timone, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université UMR 7289, Marseille, France
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Sferra A, Baillat G, Rizza T, Barresi S, Flex E, Tasca G, D'Amico A, Bellacchio E, Ciolfi A, Caputo V, Cecchetti S, Torella A, Zanni G, Diodato D, Piermarini E, Niceta M, Coppola A, Tedeschi E, Martinelli D, Dionisi-Vici C, Nigro V, Dallapiccola B, Compagnucci C, Tartaglia M, Haase G, Bertini E. TBCE Mutations Cause Early-Onset Progressive Encephalopathy with Distal Spinal Muscular Atrophy. Am J Hum Genet 2016; 99:974-983. [PMID: 27666369 DOI: 10.1016/j.ajhg.2016.08.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/09/2016] [Indexed: 11/19/2022] Open
Abstract
Tubulinopathies constitute a family of neurodevelopmental/neurodegenerative disorders caused by mutations in several genes encoding tubulin isoforms. Loss-of-function mutations in TBCE, encoding one of the five tubulin-specific chaperones involved in tubulin folding and polymerization, cause two rare neurodevelopmental syndromes, hypoparathyroidism-retardation-dysmorphism and Kenny-Caffey syndrome. Although a missense mutation in Tbce has been associated with progressive distal motor neuronopathy in the pmn/pmn mice, no similar degenerative phenotype has been recognized in humans. We report on the identification of an early-onset and progressive neurodegenerative encephalopathy with distal spinal muscular atrophy resembling the phenotype of pmn/pmn mice and caused by biallelic TBCE mutations, with the c.464T>A (p.Ile155Asn) change occurring at the heterozygous/homozygous state in six affected subjects from four unrelated families originated from the same geographical area in Southern Italy. Western blot analysis of patient fibroblasts documented a reduced amount of TBCE, suggestive of rapid degradation of the mutant protein, similarly to what was observed in pmn/pmn fibroblasts. The impact of TBCE mutations on microtubule polymerization was determined using biochemical fractionation and analyzing the nucleation and growth of microtubules at the centrosome and extracentrosomal sites after treatment with nocodazole. Primary fibroblasts obtained from affected subjects displayed a reduced level of polymerized α-tubulin, similarly to tail fibroblasts of pmn/pmn mice. Moreover, markedly delayed microtubule re-polymerization and abnormal mitotic spindles with disorganized microtubule arrangement were also documented. Although loss of function of TBCE has been documented to impact multiple developmental processes, the present findings provide evidence that hypomorphic TBCE mutations primarily drive neurodegeneration.
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Affiliation(s)
- Antonella Sferra
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Gilbert Baillat
- Institut de Neurosciences de la Timone, UMR 7289 CNRS Aix-Marseille University, 13005 Marseille, France
| | - Teresa Rizza
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Sabina Barresi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Elisabetta Flex
- Department of Hematology, Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Giorgio Tasca
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Adele D'Amico
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Emanuele Bellacchio
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Andrea Ciolfi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy; Centro di Ricerca per gli alimenti e la nutrizione, CREA, 00178 Rome, Italy
| | - Viviana Caputo
- Department of Experimental Medicine, Università La Sapienza, 00161 Rome, Italy
| | - Serena Cecchetti
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Annalaura Torella
- Department of Biochemistry, Biophysics and General Pathology, Seconda Università degli Studi di Napoli, 80138 Naples, Italy; Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Ginevra Zanni
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Daria Diodato
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Emanuela Piermarini
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Marcello Niceta
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Antonietta Coppola
- Department of Neuroscience, Reproductive and Odontostomatological Sciences, Università degli Studi di Napoli Federico II, 80131 Naples, Italy
| | - Enrico Tedeschi
- Department of Advanced Biomedical Sciences, Università degli Studi di Napoli Federico II, 80131 Naples, Italy
| | - Diego Martinelli
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Carlo Dionisi-Vici
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Vincenzo Nigro
- Department of Biochemistry, Biophysics and General Pathology, Seconda Università degli Studi di Napoli, 80138 Naples, Italy; Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Bruno Dallapiccola
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Claudia Compagnucci
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy.
| | - Georg Haase
- Institut de Neurosciences de la Timone, UMR 7289 CNRS Aix-Marseille University, 13005 Marseille, France
| | - Enrico Bertini
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy.
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15
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Méphon-Gaspard A, Boca M, Pioche-Durieu C, Desforges B, Burgo A, Hamon L, Piétrement O, Pastré D. Role of tau in the spatial organization of axonal microtubules: keeping parallel microtubules evenly distributed despite macromolecular crowding. Cell Mol Life Sci 2016; 73:3745-60. [PMID: 27076215 PMCID: PMC5002045 DOI: 10.1007/s00018-016-2216-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 03/24/2016] [Accepted: 04/01/2016] [Indexed: 02/07/2023]
Abstract
Opposing views have been proposed regarding the role of tau, the principal microtubule-associated protein in axons. On the one hand, tau forms cross-bridges at the interface between microtubules and induces microtubule bundling in neurons. On the other hand, tau is also considered a polymer brush which efficiently separates microtubules. In mature axons, microtubules are indeed arranged in parallel arrays and are well separated from each other. To reconcile these views, we developed a mechanistic model based on in vitro and cellular approaches combined to analytical and numerical analyses. The results indicate that tau forms long-range cross-bridges between microtubules under macromolecular crowding conditions. Tau cross-bridges prevent the redistribution of tau away from the interface between microtubules, which would have occurred in the polymer brush model. Consequently, the short-range attractive force between microtubules induced by macromolecular crowding is avoided and thus microtubules remain well separated from each other. Interestingly, in this unified model, tau diffusion on microtubules enables to keep microtubules evenly distributed in axonal sections at low tau levels.
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Affiliation(s)
- Alix Méphon-Gaspard
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1204, Université Evry-Val d'Essonne, Evry, 91025, France
| | - Mirela Boca
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1204, Université Evry-Val d'Essonne, Evry, 91025, France
| | - Catherine Pioche-Durieu
- UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, Villejuif, 94805, France
| | - Bénédicte Desforges
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1204, Université Evry-Val d'Essonne, Evry, 91025, France
| | - Andrea Burgo
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1204, Université Evry-Val d'Essonne, Evry, 91025, France
| | - Loic Hamon
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1204, Université Evry-Val d'Essonne, Evry, 91025, France
| | - Olivier Piétrement
- UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, Villejuif, 94805, France
| | - David Pastré
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1204, Université Evry-Val d'Essonne, Evry, 91025, France.
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16
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Neurofilament depletion improves microtubule dynamics via modulation of Stat3/stathmin signaling. Acta Neuropathol 2016; 132:93-110. [PMID: 27021905 PMCID: PMC4911381 DOI: 10.1007/s00401-016-1564-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 03/14/2016] [Accepted: 03/15/2016] [Indexed: 12/31/2022]
Abstract
In neurons, microtubules form a dense array within axons, and the stability and function of this microtubule network is modulated by neurofilaments. Accumulation of neurofilaments has been observed in several forms of neurodegenerative diseases, but the mechanisms how elevated neurofilament levels destabilize axons are unknown so far. Here, we show that increased neurofilament expression in motor nerves of pmn mutant mice, a model of motoneuron disease, causes disturbed microtubule dynamics. The disease is caused by a point mutation in the tubulin-specific chaperone E (Tbce) gene, leading to an exchange of the most C-terminal amino acid tryptophan to glycine. As a consequence, the TBCE protein becomes instable which then results in destabilization of axonal microtubules and defects in axonal transport, in particular in motoneurons. Depletion of neurofilament increases the number and regrowth of microtubules in pmn mutant motoneurons and restores axon elongation. This effect is mediated by interaction of neurofilament with the stathmin complex. Accumulating neurofilaments associate with stathmin in axons of pmn mutant motoneurons. Depletion of neurofilament by Nefl knockout increases Stat3–stathmin interaction and stabilizes the microtubules in pmn mutant motoneurons. Consequently, counteracting enhanced neurofilament expression improves axonal maintenance and prolongs survival of pmn mutant mice. We propose that this mechanism could also be relevant for other neurodegenerative diseases in which neurofilament accumulation and loss of microtubules are prominent features.
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Bellouze S, Baillat G, Buttigieg D, de la Grange P, Rabouille C, Haase G. Stathmin 1/2-triggered microtubule loss mediates Golgi fragmentation in mutant SOD1 motor neurons. Mol Neurodegener 2016; 11:43. [PMID: 27277231 PMCID: PMC4899909 DOI: 10.1186/s13024-016-0111-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/01/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Pathological Golgi fragmentation represents a constant pre-clinical feature of many neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) but its molecular mechanisms remain hitherto unclear. RESULTS Here, we show that the severe Golgi fragmentation in transgenic mutant SOD1(G85R) and SOD1(G93A) mouse motor neurons is associated with defective polymerization of Golgi-derived microtubules, loss of the COPI coat subunit β-COP, cytoplasmic dispersion of the Golgi tether GM130, strong accumulation of the ER-Golgi v-SNAREs GS15 and GS28 as well as tubular/vesicular Golgi fragmentation. Data mining, transcriptomic and protein analyses demonstrate that both SOD1 mutants cause early presymptomatic and rapidly progressive up-regulation of the microtubule-destabilizing proteins Stathmins 1 and 2. Remarkably, mutant SOD1-triggered Golgi fragmentation and Golgi SNARE accumulation are recapitulated by Stathmin 1/2 overexpression but completely rescued by Stathmin 1/2 knockdown or the microtubule-stabilizing drug Taxol. CONCLUSIONS We conclude that Stathmin-triggered microtubule destabilization mediates Golgi fragmentation in mutant SOD1-linked ALS and potentially also in related motor neuron diseases.
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Affiliation(s)
- Sarah Bellouze
- Institut de Neurosciences de la Timone, UMR 7289, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université, 27 bd Jean Moulin, 13005 Marseille, France
| | - Gilbert Baillat
- Institut de Neurosciences de la Timone, UMR 7289, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université, 27 bd Jean Moulin, 13005 Marseille, France
| | - Dorothée Buttigieg
- Institut de Neurosciences de la Timone, UMR 7289, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université, 27 bd Jean Moulin, 13005 Marseille, France
| | - Pierre de la Grange
- GenoSplice technology, iPEPS - ICM, Hôpital Pitié Salpêtrière, 47/83, bd de l'Hôpital, 75013 Paris, France
| | - Catherine Rabouille
- Department of Cell Biology, Hubrecht Institute of the KNAW & UMC Utrecht, Uppsalalaan 8, 3584 CT Utrecht, Netherlands
| | - Georg Haase
- Institut de Neurosciences de la Timone, UMR 7289, Centre National de la Recherche Scientifique (CNRS) and Aix-Marseille Université, 27 bd Jean Moulin, 13005 Marseille, France.
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18
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Haase G, Rabouille C. Golgi Fragmentation in ALS Motor Neurons. New Mechanisms Targeting Microtubules, Tethers, and Transport Vesicles. Front Neurosci 2015; 9:448. [PMID: 26696811 PMCID: PMC4672084 DOI: 10.3389/fnins.2015.00448] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/13/2015] [Indexed: 12/12/2022] Open
Abstract
Pathological alterations of the Golgi apparatus, such as its fragmentation represent an early pre-clinical feature of many neurodegenerative diseases and have been widely studied in the motor neuron disease amyotrophic lateral sclerosis (ALS). Yet, the underlying molecular mechanisms have remained cryptic. In principle, Golgi fragmentation may result from defects in three major classes of proteins: structural Golgi proteins, cytoskeletal proteins and molecular motors, as well as proteins mediating transport to and through the Golgi. Here, we present the different mechanisms that may underlie Golgi fragmentation in animal and cellular models of ALS linked to mutations in SOD1, TARDBP (TDP-43), VAPB, and C9Orf72 and we propose a novel one based on findings in progressive motor neuronopathy (pmn) mice. These mice are mutated in the TBCE gene encoding the cis-Golgi localized tubulin-binding cofactor E, one of five chaperones that assist in tubulin folding and microtubule polymerization. Loss of TBCE leads to alterations in Golgi microtubules, which in turn impedes on the maintenance of the Golgi architecture. This is due to down-regulation of COPI coat components, dispersion of Golgi tethers and strong accumulation of ER-Golgi SNAREs. These effects are partially rescued by the GTPase ARF1 through recruitment of TBCE to the Golgi. We hypothesize that defects in COPI vesicles, microtubules and their interaction may also underlie Golgi fragmentation in human ALS linked to other mutations, spinal muscular atrophy (SMA), and related motor neuron diseases. We also discuss the functional relevance of pathological Golgi alterations, in particular their potential causative, contributory, or compensatory role in the degeneration of motor neuron cell bodies, axons and synapses.
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Affiliation(s)
- Georg Haase
- Centre National de la Recherche Scientifique and Aix-Marseille Université UMR 7289, Institut de Neurosciences de la Timone Marseille, France
| | - Catherine Rabouille
- The Department of Cell Biology, Hubrecht Institute of the Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht Utrecht, Netherlands
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19
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Sanders AAWM, Kaverina I. Nucleation and Dynamics of Golgi-derived Microtubules. Front Neurosci 2015; 9:431. [PMID: 26617483 PMCID: PMC4639703 DOI: 10.3389/fnins.2015.00431] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 10/23/2015] [Indexed: 11/13/2022] Open
Abstract
Integrity of the Golgi apparatus requires the microtubule (MT) network. A subset of MTs originates at the Golgi itself, which in this case functions as a MT-organizing center (MTOC). Golgi-derived MTs serve important roles in post-Golgi trafficking, maintenance of Golgi integrity, cell polarity and motility, as well as cell type-specific functions, including neurite outgrowth/branching. Here, we discuss possible models describing the formation and dynamics of Golgi-derived MTs. How Golgi-derived MTs are formed is not fully understood. A widely discussed model implicates that the critical step of the process is recruitment of molecular factors, which drive MT nucleation (γ-tubulin ring complex, or γ-TuRC), to the Golgi membrane via specific scaffolding interactions. Based on recent findings, we propose to introduce an additional level of regulation, whereby MT-binding proteins and/or local tubulin dimer concentration at the Golgi helps to overcome kinetic barriers at the initial nucleation step. According to our model, emerging MTs are subsequently stabilized by Golgi-associated MT-stabilizing proteins. We discuss molecular factors potentially involved in all three steps of MT formation. To preserve proper cell functioning, a balance must be maintained between MT subsets at the centrosome and the Golgi. Recent work has shown that certain centrosomal factors are important in maintaining this balance, suggesting a close connection between regulation of centrosomal and Golgi-derived MTs. Finally, we will discuss potential functions of Golgi-derived MTs based on their nucleation site location within a Golgi stack.
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Affiliation(s)
- Anna A W M Sanders
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Irina Kaverina
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center Nashville, TN, USA
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Rab1-dependent ER-Golgi transport dysfunction is a common pathogenic mechanism in SOD1, TDP-43 and FUS-associated ALS. Acta Neuropathol 2015; 130:679-97. [PMID: 26298469 DOI: 10.1007/s00401-015-1468-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 12/12/2022]
Abstract
Several diverse proteins are linked genetically/pathologically to neurodegeneration in amyotrophic lateral sclerosis (ALS) including SOD1, TDP-43 and FUS. Using a variety of cellular and biochemical techniques, we demonstrate that ALS-associated mutant TDP-43, FUS and SOD1 inhibit protein transport between the endoplasmic reticulum (ER) and Golgi apparatus in neuronal cells. ER-Golgi transport was also inhibited in embryonic cortical and motor neurons obtained from a widely used animal model (SOD1(G93A) mice), validating this mechanism as an early event in disease. Each protein inhibited transport by distinct mechanisms, but each process was dependent on Rab1. Mutant TDP-43 and mutant FUS both inhibited the incorporation of secretory protein cargo into COPII vesicles as they bud from the ER, and inhibited transport from ER to the ER-Golgi intermediate (ERGIC) compartment. TDP-43 was detected on the cytoplasmic face of the ER membrane, whereas FUS was present within the ER, suggesting that transport is inhibited from the cytoplasm by mutant TDP-43, and from the ER by mutant FUS. In contrast, mutant SOD1 destabilised microtubules and inhibited transport from the ERGIC compartment to Golgi, but not from ER to ERGIC. Rab1 performs multiple roles in ER-Golgi transport, and over-expression of Rab1 restored ER-Golgi transport, and prevented ER stress, mSOD1 inclusion formation and induction of apoptosis, in cells expressing mutant TDP-43, FUS or SOD1. Rab1 also co-localised extensively with mutant TDP-43, FUS and SOD1 in neuronal cells, and Rab1 formed inclusions in motor neurons of spinal cords from sporadic ALS patients, which were positive for ubiquitinated TDP-43, implying that Rab1 is misfolded and dysfunctional in sporadic disease. These results demonstrate that ALS-mutant forms of TDP-43, FUS, and SOD1 all perturb protein transport in the early secretory pathway, between ER and Golgi compartments. These data also imply that restoring Rab1-mediated ER-Golgi transport is a novel therapeutic target in ALS.
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Linking cell surface receptors to microtubules: tubulin folding cofactor D mediates Dscam functions during neuronal morphogenesis. J Neurosci 2015; 35:1979-90. [PMID: 25653356 DOI: 10.1523/jneurosci.0973-14.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Formation of functional neural networks requires the coordination of cell surface receptors and downstream signaling cascades, which eventually leads to dynamic remodeling of the cytoskeleton. Although a number of guidance receptors affecting actin cytoskeleton remodeling have been identified, it is relatively unknown how microtubule dynamics are regulated by guidance receptors. We used Drosophila olfactory projection neurons to study the molecular mechanisms of neuronal morphogenesis. Dendrites of each projection neuron target a single glomerulus of ∼50 glomeruli in the antennal lobe, and the axons show stereotypical pattern of terminal arborization. In the course of genetic analysis of the dachsous mutant allele (ds(UAO71)), we identified a mutation in the tubulin folding cofactor D gene (TBCD) as a background mutation. TBCD is one of five tubulin-folding cofactors required for the formation of α- and β-tubulin heterodimers. Single-cell clones of projection neurons homozygous for the TBCD mutation displayed disruption of microtubules, resulting in ectopic arborization of dendrites, and axon degeneration. Interestingly, overexpression of TBCD also resulted in microtubule disruption and ectopic dendrite arborization, suggesting that an optimum level of TBCD is crucial for in vivo neuronal morphogenesis. We further found that TBCD physically interacts with the intracellular domain of Down syndrome cell adhesion molecule (Dscam), which is important for neural development and has been implicated in Down syndrome. Genetic analyses revealed that TBCD cooperates with Dscam in vivo. Our study may offer new insights into the molecular mechanism underlying the altered neural networks in cognitive disabilities of Down syndrome.
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Bloch-Gallego E. Mechanisms controlling neuromuscular junction stability. Cell Mol Life Sci 2015; 72:1029-43. [PMID: 25359233 PMCID: PMC11113273 DOI: 10.1007/s00018-014-1768-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 10/06/2014] [Accepted: 10/17/2014] [Indexed: 01/01/2023]
Abstract
The neuromuscular junction (NMJ) is the synaptic connection between motor neurons and muscle fibers. It is involved in crucial processes such as body movements and breathing. Its proper development requires the guidance of motor axons toward their specific targets, the development of multi-innervated myofibers, and a selective synapse stabilization. It first consists of the removal of excessive motor axons on myofibers, going from multi-innervation to a single innervation of each myofiber. Whereas guidance cues of motor axons toward their specific muscular targets are well characterized, only few molecular and cellular cues have been reported as clues for selecting and stabilizing specific neuromuscular junctions. We will first provide a brief summary on NMJ development. We will then review molecular cues that are involved in NMJ stabilization, in both pre- and post-synaptic compartments, considering motor neurons and Schwann cells on the one hand, and muscle on the other hand. We will provide links with pathologies and highlight advances that can be brought both by basic research on NMJ development and clinical data resulting from the analyses of neurodegeneration of synaptic connections to obtain a better understanding of this process. The goal of this review is to highlight the findings toward understanding the roles of poly- or single-innervations and the underlying mechanisms of NMJ stabilization.
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Affiliation(s)
- Evelyne Bloch-Gallego
- Institut Cochin, INSERM U. 1016, CNRS UMR 8104, University Paris Descartes 24, rue du Fbg St-Jacques, 75014, Paris, France,
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23
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Pease SE, Segal RA. Preserve and protect: maintaining axons within functional circuits. Trends Neurosci 2014; 37:572-82. [PMID: 25167775 DOI: 10.1016/j.tins.2014.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 07/21/2014] [Accepted: 07/27/2014] [Indexed: 12/14/2022]
Abstract
During development, neural circuits are initially generated by exuberant innervation and are rapidly refined by selective preservation and elimination of axons. The establishment and maintenance of functional circuits therefore requires coordination of axon survival and degeneration pathways. Both developing and mature circuits rely on interdependent mitochondrial and cytoskeletal components to maintain axonal health and homeostasis; injury or diseases that impinge on these components frequently cause pathologic axon loss. Here, we review recent findings that identify mechanisms of axonal preservation in the contexts of development, injury, and disease.
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Affiliation(s)
- Sarah E Pease
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Rosalind A Segal
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
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24
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Bellouze S, Schäfer MK, Buttigieg D, Baillat G, Rabouille C, Haase G. Golgi fragmentation in pmn mice is due to a defective ARF1/TBCE cross-talk that coordinates COPI vesicle formation and tubulin polymerization. Hum Mol Genet 2014; 23:5961-75. [DOI: 10.1093/hmg/ddu320] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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25
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Ruiz M, Martínez-Vidal AF, Morales JM, Monleón D, Giménez Y Ribotta M. Neurodegenerative changes are prevented by Erythropoietin in the pmn model of motoneuron degeneration. Neuropharmacology 2014; 83:137-53. [PMID: 24769002 DOI: 10.1016/j.neuropharm.2014.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 03/02/2014] [Accepted: 04/10/2014] [Indexed: 11/29/2022]
Abstract
Motoneuron diseases are fatal neurodegenerative disorders characterized by a progressive loss of motoneurons, muscle weakness and premature death. The progressive motor neuronopathy (pmn) mutant mouse has been considered a good model for the autosomal recessive childhood form of spinal muscular atrophy (SMA). Here, we investigated the therapeutic potential of Erythropoietin (Epo) on this mutant mouse. Symptomatic or pre-symptomatic treatment with Epo significantly prolongs lifespan by 84.6% or 87.2% respectively. Epo preserves muscle strength and significantly attenuates behavioural motor deficits of mutant pmn mice. Histological and metabolic changes in the spinal cord evaluated by immunohistochemistry, western blot, and high-resolution (1)H-NMR spectroscopy were also greatly prevented by Epo-treatment. Our results illustrate the efficacy of Epo in improving quality of life of mutant pmn mice and open novel therapeutic pathways for motoneuron diseases.
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Affiliation(s)
- Marta Ruiz
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad Miguel Hernández (UMH), Av. Ramón y Cajal s/n, 03550 San Juan de Alicante, Alicante, Spain
| | - Ana Fe Martínez-Vidal
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad Miguel Hernández (UMH), Av. Ramón y Cajal s/n, 03550 San Juan de Alicante, Alicante, Spain
| | - José Manuel Morales
- Unidad Central de Investigación en Medicina, Universidad de Valencia, Valencia, Spain
| | - Daniel Monleón
- Fundación de Investigación del Hospital Clínico Universitario de Valencia (FIHCUV), Valencia, Spain
| | - Minerva Giménez Y Ribotta
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad Miguel Hernández (UMH), Av. Ramón y Cajal s/n, 03550 San Juan de Alicante, Alicante, Spain.
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26
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Atkin JD, Farg MA, Soo KY, Walker AK, Halloran M, Turner BJ, Nagley P, Horne MK. Mutant SOD1 inhibits ER-Golgi transport in amyotrophic lateral sclerosis. J Neurochem 2014; 129:190-204. [PMID: 24134191 DOI: 10.1111/jnc.12493] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 09/16/2013] [Accepted: 10/15/2013] [Indexed: 12/16/2022]
Abstract
Cu/Zn-superoxide dismutase is misfolded in familial and sporadic amyotrophic lateral sclerosis, but it is not clear how this triggers endoplasmic reticulum (ER) stress or other pathogenic processes. Here, we demonstrate that mutant SOD1 (mSOD1) is predominantly found in the cytoplasm in neuronal cells. Furthermore, we show that mSOD1 inhibits secretory protein transport from the ER to Golgi apparatus. ER-Golgi transport is linked to ER stress, Golgi fragmentation and axonal transport and we also show that inhibition of ER-Golgi trafficking preceded ER stress, Golgi fragmentation, protein aggregation and apoptosis in cells expressing mSOD1. Restoration of ER-Golgi transport by over-expression of coatomer coat protein II subunit Sar1 protected against inclusion formation and apoptosis, thus linking dysfunction in ER-Golgi transport to cellular pathology. These findings thus link several cellular events in amyotrophic lateral sclerosis into a single mechanism occurring early in mSOD1 expressing cells.
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Affiliation(s)
- Julie D Atkin
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Melbourne, Australia; Department of Florey Neuroscience, University of Melbourne, Parkville, Melbourne, Australia
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27
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Rak K, Frenz S, Radeloff A, Groh J, Jablonka S, Martini R, Hagen R, Mlynski R. Mutation of the TBCE gene causes disturbance of microtubules in the auditory nerve and cochlear outer hair cell degeneration accompanied by progressive hearing loss in the pmn/pmn mouse. Exp Neurol 2013; 250:333-40. [PMID: 24120439 DOI: 10.1016/j.expneurol.2013.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/26/2013] [Accepted: 10/03/2013] [Indexed: 10/26/2022]
Abstract
The progressive motor neuronopathy (pmn/pmn) mouse, an animal model for a fast developing human motor neuron disorder, is additionally characterized by simultaneous progressive sensorineural hearing loss. The gene defect in the pmn/pmn mouse is localized to a missense mutation in the tubulin-specific chaperone E (TBCE) gene on mouse chromosome 13, which is one of the five tubulin-specific chaperons involved in tubulin folding and dimerization. The missense mutation leads to a disturbance of tubulin structures in the auditory nerve and a progressive outer hair cell loss due to apoptosis, which is accompanied by highly elevated ABR-thresholds and loss of DPOAEs. In addition the TBCE protein is selectively expressed in the outer hair cells and the transcellular processes of the inner pillar cells in the cochlea of control and pmn/pmn mouse. We conclude from our study that the mutation of the TBCE gene affects the auditory nerve and the cochlear hair cells simultaneously, leading to progressive hearing loss. This animal model will give the chance to test possible therapeutic strategies in special forms of hearing loss, in which the auditory nerve and the cochlear hair cells are simultaneously affected.
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Affiliation(s)
- Kristen Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Wuerzburg, Germany; Comprehensive Hearing Center, University of Wuerzburg, Germany
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28
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Prokop A. The intricate relationship between microtubules and their associated motor proteins during axon growth and maintenance. Neural Dev 2013; 8:17. [PMID: 24010872 PMCID: PMC3846809 DOI: 10.1186/1749-8104-8-17] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 08/14/2013] [Indexed: 12/15/2022] Open
Abstract
The hallmarks of neurons are their slender axons which represent the longest cellular processes of animals and which act as the cables that electrically wire the brain, and the brain to the body. Axons extend along reproducible paths during development and regeneration, and they have to be maintained for the lifetime of an organism. Both axon extension and maintenance essentially depend on the microtubule (MT) cytoskeleton. For this, MTs organize into parallel bundles that are established through extension at the leading axon tips within growth cones, and these bundles then form the architectural backbones, as well as the highways for axonal transport essential for supply and intracellular communication. Axon transport over these enormous distances takes days or even weeks and is a substantial logistical challenge. It is performed by kinesins and dynein/dynactin, which are molecular motors that form close functional links to the MTs they walk along. The intricate machinery which regulates MT dynamics, axonal transport and the motors is essential for nervous system development and function, and its investigation has huge potential to bring urgently required progress in understanding the causes of many developmental and degenerative brain disorders. During the last years new explanations for the highly specific properties of axonal MTs and for their close functional links to motor proteins have emerged, and it has become increasingly clear that motors play active roles also in regulating axonal MT networks. Here, I will provide an overview of these new developments.
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Affiliation(s)
- Andreas Prokop
- Faculty of Life Sciences, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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29
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Jablonka S, Dombert B, Asan E, Sendtner M. Mechanisms for axon maintenance and plasticity in motoneurons: alterations in motoneuron disease. J Anat 2013; 224:3-14. [PMID: 24007389 DOI: 10.1111/joa.12097] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2013] [Indexed: 12/12/2022] Open
Abstract
In motoneuron disease and other neurodegenerative disorders, the loss of synapses and axon branches occurs early but is compensated by sprouting of neighboring axon terminals. Defective local axonal signaling for maintenance and dynamics of the axonal microtubule and actin cytoskeleton plays a central role in this context. The molecular mechanisms that lead to defective cytoskeleton architecture in two mouse models of motoneuron disease are summarized and discussed in this manuscript. In the progressive motor neuropathy (pmn) mouse model of motoneuron disease that is caused by a mutation in the tubulin-specific chaperone E gene, death of motoneuron cell bodies appears as a consequence of axonal degeneration. Treatment with bcl-2 overexpression or with glial-derived neurotrophic factor prevents loss of motoneuron cell bodies but does not influence the course of disease. In contrast, treatment with ciliary neurotrophic factor (CNTF) significantly delays disease onset and prolongs survival of pmn mice. This difference is due to the activation of Stat-3 via the CNTF receptor complex in axons of pmn mutant motoneurons. Most of the activated Stat-3 protein is not transported to the nucleus to activate transcription, but interacts locally in axons with stathmin, a protein that destabilizes microtubules. This interaction plays a major role in CNTF signaling for microtubule dynamics in axons. In Smn-deficient mice, a model of spinal muscular atrophy, defects in axonal translocation of β-actin mRNA and possibly other mRNA species have been observed. Moreover, the regulation of local protein synthesis in response to signals from neurotrophic factors and extracellular matrix proteins is altered in motoneurons from this model of motoneuron disease. These findings indicate that local signals are important for maintenance and plasticity of axonal branches and neuromuscular endplates, and that disturbances in these signaling mechanisms could contribute to the pathophysiology of motoneuron diseases.
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Affiliation(s)
- Sibylle Jablonka
- Institute for Clinical Neurobiology, University Hospital, University of Wuerzburg, Wuerzburg, Germany
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30
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Vinsant S, Mansfield C, Jimenez-Moreno R, Del Gaizo Moore V, Yoshikawa M, Hampton TG, Prevette D, Caress J, Oppenheim RW, Milligan C. Characterization of early pathogenesis in the SOD1(G93A) mouse model of ALS: part II, results and discussion. Brain Behav 2013; 3:431-57. [PMID: 24381813 PMCID: PMC3869683 DOI: 10.1002/brb3.142] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/21/2013] [Accepted: 03/22/2013] [Indexed: 12/12/2022] Open
Abstract
Pathological events are well characterized in amyotrophic lateral sclerosis (ALS) mouse models, but review of the literature fails to identify a specific initiating event that precipitates disease pathology. There is now growing consensus in the field that axon and synapses are first cellular sites of degeneration, but controversy exists over whether axon and synapse loss is initiated autonomously at those sites or by pathology in the cell body, in nonneuronal cells or even in nonmotoneurons (MNs). Previous studies have identified pathological events in the mutant superoxide dismutase 1 (SOD1) models involving spinal cord, peripheral axons, neuromuscular junctions (NMJs), or muscle; however, few studies have systematically examined pathogenesis at multiple sites in the same study. We have performed ultrastructural examination of both central and peripheral components of the neuromuscular system in the SOD1(G93A) mouse model of ALS. Twenty percent of MNs undergo degeneration by P60, but NMJ innervation in fast fatigable muscles is reduced by 40% by P30. Gait alterations and muscle weakness were also found at P30. There was no change in axonal transport prior to initial NMJ denervation. Mitochondrial morphological changes are observed at P7 and become more prominent with disease progression. At P30 there was a significant decrease in excitatory axo-dendritic and axo-somatic synapses with an increase in C-type axo-somatic synapses. Our study examined early pathology in both peripheral and central neuromuscular system. The muscle denervation is associated with functional motor deficits and begins during the first postnatal month in SOD1(G93A) mice. Physiological dysfunction and pathology in the mitochondria of synapses and MN soma and dendrites occur, and disease onset in these animals begins more than 2 months earlier than originally thought. This information may be valuable for designing preclinical trials that are more likely to impact disease onset and progression.
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Affiliation(s)
- Sharon Vinsant
- Department of Neurobiology and Anatomy, The Neuroscience Program and The ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
| | - Carol Mansfield
- Department of Neurobiology and Anatomy, The Neuroscience Program and The ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
| | - Ramon Jimenez-Moreno
- Department of Neurobiology and Anatomy, The Neuroscience Program and The ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
| | | | - Masaaki Yoshikawa
- Department of Neurobiology and Anatomy, The Neuroscience Program and The ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
| | | | - David Prevette
- Department of Neurobiology and Anatomy, The Neuroscience Program and The ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
| | - James Caress
- Department of Neurology and the ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
| | - Ronald W Oppenheim
- Department of Neurobiology and Anatomy, The Neuroscience Program and The ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
| | - Carol Milligan
- Department of Neurobiology and Anatomy, The Neuroscience Program and The ALS Center, Wake Forest University School of Medicine Winston-Salem, North Carolina
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Franker MAM, Hoogenraad CC. Microtubule-based transport - basic mechanisms, traffic rules and role in neurological pathogenesis. J Cell Sci 2013; 126:2319-29. [PMID: 23729742 DOI: 10.1242/jcs.115030] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Microtubule-based transport is essential for neuronal function because of the large distances that must be traveled by various building blocks and cellular materials. Recent studies in various model systems have unraveled several regulatory mechanisms and traffic rules that control the specificity, directionality and delivery of neuronal cargos. Local microtubule cues, opposing motor activity and cargo-adaptors that regulate motor activity control microtubule-based transport in neurons. Impairment of intracellular transport is detrimental to neurons and has emerged as a common factor in several neurological disorders. Genetic approaches have revealed strong links between intracellular transport processes and the pathogenesis of neurological diseases in both the central and peripheral nervous system. This Commentary highlights recent advances in these areas and discusses the transport defects that are associated with the development of neurological diseases.
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Affiliation(s)
- Mariella A M Franker
- Cell Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
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32
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Selvaraj BT, Frank N, Bender FLP, Asan E, Sendtner M. Local axonal function of STAT3 rescues axon degeneration in the pmn model of motoneuron disease. ACTA ACUST UNITED AC 2013; 199:437-51. [PMID: 23109669 PMCID: PMC3483126 DOI: 10.1083/jcb.201203109] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Axonal maintenance, plasticity, and regeneration are influenced by signals from neighboring cells, in particular Schwann cells of the peripheral nervous system. Schwann cells produce neurotrophic factors, but the mechanisms by which ciliary neurotrophic factor (CNTF) and other neurotrophic molecules modify the axonal cytoskeleton are not well understood. In this paper, we show that activated signal transducer and activator of transcription-3 (STAT3), an intracellular mediator of the effects of CNTF and other neurotrophic cytokines, acts locally in axons of motoneurons to modify the tubulin cytoskeleton. Specifically, we show that activated STAT3 interacted with stathmin and inhibited its microtubule-destabilizing activity. Thus, ectopic CNTF-mediated activation of STAT3 restored axon elongation and maintenance in motoneurons from progressive motor neuronopathy mutant mice, a mouse model of motoneuron disease. This mechanism could also be relevant for other neurodegenerative diseases and provide a target for new therapies for axonal degeneration.
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Kurepa J, Wang S, Smalle J. The role of 26S proteasome-dependent proteolysis in the formation and restructuring of microtubule networks. PLANT SIGNALING & BEHAVIOR 2012; 7:1289-1295. [PMID: 22902696 PMCID: PMC3493416 DOI: 10.4161/psb.21543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this review, we summarize the evidence pointing at the important role of 26S proteasome-dependent proteolysis in the regulation of microtubule synthesis and microtubule dynamics. Because most of the advances in this relatively unexplored research field originate from yeast and animal studies, we have considered those studies that describe the role of proteolysis in processes that are evolutionarily conserved and known to exist in plants. In addition, we place particular emphasis on the proteasome-dependent degradation of plant-specific microtubule-associated protein SPIRAL1 and its function in MT rearrangements associated with salt stress.
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Baffet AD, Benoit B, Januschke J, Audo J, Gourhand V, Roth S, Guichet A. Drosophila tubulin-binding cofactor B is required for microtubule network formation and for cell polarity. Mol Biol Cell 2012; 23:3591-601. [PMID: 22855530 PMCID: PMC3442407 DOI: 10.1091/mbc.e11-07-0633] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Microtubules (MTs) are essential for cell division, shape, intracellular transport, and polarity. MT stability is regulated by many factors, including MT-associated proteins and proteins controlling the amount of free tubulin heterodimers available for polymerization. Tubulin-binding cofactors are potential key regulators of free tubulin concentration, since they are required for α-β-tubulin dimerization in vitro. In this paper, we show that mutation of the Drosophila tubulin-binding cofactor B (dTBCB) affects the levels of both α- and β-tubulins and dramatically destabilizes the MT network in different fly tissues. However, we find that dTBCB is dispensable for the early MT-dependent steps of oogenesis, including cell division, and that dTBCB is not required for mitosis in several tissues. In striking contrast, the absence of dTBCB during later stages of oogenesis causes major defects in cell polarity. We show that dTBCB is required for the polarized localization of the axis-determining mRNAs within the oocyte and for the apico-basal polarity of the surrounding follicle cells. These results establish a developmental function for the dTBCB gene that is essential for viability and MT-dependent cell polarity, but not cell division.
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Affiliation(s)
- Alexandre D Baffet
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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35
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Functional inactivation of the genome-wide association study obesity gene neuronal growth regulator 1 in mice causes a body mass phenotype. PLoS One 2012; 7:e41537. [PMID: 22844493 PMCID: PMC3402391 DOI: 10.1371/journal.pone.0041537] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 06/22/2012] [Indexed: 12/21/2022] Open
Abstract
To date, genome-wide association studies (GWAS) have identified at least 32 novel loci for obesity and body mass-related traits. However, the causal genetic variant and molecular mechanisms of specific susceptibility genes in relation to obesity are yet to be fully confirmed and characterised. Here, we examined whether the candidate gene NEGR1 encoding the neuronal growth regulator 1, also termed neurotractin or Kilon, accounts for the obesity association. To characterise the function of NEGR1 for body weight control in vivo, we generated two novel mutant mouse lines, including a constitutive NEGR1-deficient mouse line as well as an ENU-mutagenised line carrying a loss-of-function mutation (Negr1-I87N) and performed metabolic phenotypic analyses. Ablation of NEGR1 results in a small but steady reduction of body mass in both mutant lines, accompanied with a small reduction in body length in the Negr1-I87N mutants. Magnetic resonance scanning reveals that the reduction of body mass in Negr1-I87N mice is due to a reduced proportion of lean mass. Negr1-I87N mutants display reduced food intake and physical activity while normalised energy expenditure remains unchanged. Expression analyses confirmed the brain-specific distribution of NEGR1 including strong expression in the hypothalamus. In vitro assays show that NEGR1 promotes cell-cell adhesion and neurite growth of hypothalamic neurons. Our results indicate a role of NEGR1 in the control of body weight and food intake. This study provides evidence that supports the link of the GWAS candidate gene NEGR1 with body weight control.
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Molecular motor proteins and amyotrophic lateral sclerosis. Int J Mol Sci 2011; 12:9057-82. [PMID: 22272119 PMCID: PMC3257116 DOI: 10.3390/ijms12129057] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting motor neurons in the brain, brainstem and spinal cord, which is characterized by motor dysfunction, muscle dystrophy and progressive paralysis. Both inherited and sporadic forms of ALS share common pathological features, however, the initial trigger of neurodegeneration remains unknown. Motor neurons are uniquely targeted by ubiquitously expressed proteins in ALS but the reason for this selectively vulnerability is unclear. However motor neurons have unique characteristics such as very long axons, large cell bodies and high energetic metabolism, therefore placing high demands on cellular transport processes. Defects in cellular trafficking are now widely reported in ALS, including dysfunction to the molecular motors dynein and kinesin. Abnormalities to dynein in particular are linked to ALS, and defects in dynein-mediated axonal transport processes have been reported as one of the earliest pathologies in transgenic SOD1 mice. Furthermore, dynein is very highly expressed in neurons and neurons are particularly sensitive to dynein dysfunction. Hence, unravelling cellular transport processes mediated by molecular motor proteins may help shed light on motor neuron loss in ALS.
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Abstract
Axons depend critically on axonal transport both for supplying materials and for communicating with cell bodies. This chapter looks at each activity, asking what aspects are essential for axon survival. Axonal transport declines in neurodegenerative disorders, such as Alzheimer's disease, amyotrophic lateral sclerosis, and multiple sclerosis, and in normal ageing, but whether all cargoes are equally affected and what limits axon survival remains unclear. Cargoes can be differentially blocked in some disorders, either individually or in groups. Each missing protein cargo results in localized loss-of-function that can be partially modeled by disrupting the corresponding gene, sometimes with surprising results. The axonal response to losing specific proteins also depends on the rates of protein turnover and on whether the protein can be locally synthesized. Among cargoes with important axonal roles are components of the PI3 kinase, Mek/Erk, and Jnk signaling pathways, which help to communicate with cell bodies and to regulate axonal transport itself. Bidirectional trafficking of Bdnf, NT-3, and other neurotrophic factors contribute to intra- and intercellular signaling, affecting the axon's cellular environment and survival. Finally, several adhesion molecules and gangliosides are key determinants of axon survival, probably by mediating axon-glia interactions. Thus, failure of long-distance intracellular transport can deprive axons of one, few, or many cargoes. This can lead to axon degeneration either directly, through the absence of essential axonal proteins, or indirectly, through failures in communication with cell bodies and nonneuronal cells.
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L1 syndrome mutations impair neuronal L1 function at different levels by divergent mechanisms. Neurobiol Dis 2010; 40:222-37. [PMID: 20621658 DOI: 10.1016/j.nbd.2010.05.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 05/19/2010] [Accepted: 05/25/2010] [Indexed: 11/22/2022] Open
Abstract
Mutations in the human L1CAM gene cause neurodevelopmental disorders collectively referred to as L1 syndrome. Here, we investigated cellular pathomechanisms underlying two L1 syndrome mutations, R184Q and W1036L. We demonstrate that these mutations cause partial endoplasmic reticulum (ER) retention of L1, reduce L1 cell surface expression, but do not induce ER stress in neuronal NSC-34 cells. We provide evidence that surface trafficking of mutated L1 is affected by defective sorting to ER exit sites and attenuated ER export. However, in differentiated neuronal cultures and long-term cultured hippocampal slices, the L1-R184Q protein is restricted to cell bodies, whereas L1-W1036L also aberrantly localizes to dendrites. These trafficking defects preclude axonal targeting of L1, thereby affecting L1-mediated axon growth and arborization. Our results indicate that L1 syndrome mutations impair neuronal L1 function at different levels, firstly by attenuating ER export and secondly by interfering with polarized neuronal trafficking.
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Brockington A, Heath PR, Holden H, Kasher P, Bender FLP, Claes F, Lambrechts D, Sendtner M, Carmeliet P, Shaw PJ. Downregulation of genes with a function in axon outgrowth and synapse formation in motor neurones of the VEGFdelta/delta mouse model of amyotrophic lateral sclerosis. BMC Genomics 2010; 11:203. [PMID: 20346106 PMCID: PMC2861063 DOI: 10.1186/1471-2164-11-203] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Accepted: 03/26/2010] [Indexed: 12/14/2022] Open
Abstract
Background Vascular endothelial growth factor (VEGF) is an endothelial cell mitogen that stimulates vasculogenesis. It has also been shown to act as a neurotrophic factor in vitro and in vivo. Deletion of the hypoxia response element of the promoter region of the gene encoding VEGF in mice causes a reduction in neural VEGF expression, and results in adult-onset motor neurone degeneration that resembles amyotrophic lateral sclerosis (ALS). Investigating the molecular pathways to neurodegeneration in the VEGFδ/δ mouse model of ALS may improve understanding of the mechanisms of motor neurone death in the human disease. Results Microarray analysis was used to determine the transcriptional profile of laser captured spinal motor neurones of transgenic and wild-type littermates at 3 time points of disease. 324 genes were significantly differentially expressed in motor neurones of presymptomatic VEGFδ/δ mice, 382 at disease onset, and 689 at late stage disease. Massive transcriptional downregulation occurred with disease progression, associated with downregulation of genes involved in RNA processing at late stage disease. VEGFδ/δ mice showed reduction in expression, from symptom onset, of the cholesterol synthesis pathway, and genes involved in nervous system development, including axonogenesis, synapse formation, growth factor signalling pathways, cell adhesion and microtubule-based processes. These changes may reflect a reduced capacity of VEGFδ/δ mice for maintenance and remodelling of neuronal processes in the face of demands of neural plasticity. The findings are supported by the demonstration that in primary motor neurone cultures from VEGFδ/δ mice, axon outgrowth is significantly reduced compared to wild-type littermates. Conclusions Downregulation of these genes involved in axon outgrowth and synapse formation in adult mice suggests a hitherto unrecognized role of VEGF in the maintenance of neuronal circuitry. Dysregulation of VEGF may lead to neurodegeneration through synaptic regression and dying-back axonopathy.
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Affiliation(s)
- Alice Brockington
- Academic Neurology Unit, University of Sheffield, E Floor, Medical School, Beech Hill Road, Sheffield S10 2RX, UK
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Motor neuron synapse and axon defects in a C. elegans alpha-tubulin mutant. PLoS One 2010; 5:e9655. [PMID: 20300184 PMCID: PMC2836382 DOI: 10.1371/journal.pone.0009655] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Accepted: 02/02/2010] [Indexed: 12/03/2022] Open
Abstract
Regulation of microtubule dynamics underlies many fundamental cellular mechanisms including cell division, cell motility, and transport. In neurons, microtubules play key roles in cell migration, axon outgrowth, control of axon and synapse growth, and the regulated transport of vesicles and structural components of synapses. Loss of synapse and axon integrity and disruption of axon transport characterize many neurodegenerative diseases. Recently, mutations that specifically alter the assembly or stability of microtubules have been found to directly cause neurodevelopmental defects or neurodegeneration in vertebrates. We report here the characterization of a missense mutation in the C-terminal domain of C. elegans alpha-tubulin, tba-1(ju89), that disrupts motor neuron synapse and axon development. Mutant ju89 animals exhibit reduction in the number and size of neuromuscular synapses, altered locomotion, and defects in axon extension. Although null mutations of tba-1 show a nearly wild-type pattern, similar axon outgrowth defects were observed in animals lacking the beta-tubulin TBB-2. Genetic analysis reveals that tba-1(ju89) affects synapse development independent of its role in axon outgrowth. tba-1(ju89) is an altered function allele that most likely perturbs interactions between TBA-1 and specific microtubule-associated proteins that control microtubule dynamics and transport of components needed for synapse and axon growth.
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Wen HL, Lin YT, Ting CH, Lin-Chao S, Li H, Hsieh-Li HM. Stathmin, a microtubule-destabilizing protein, is dysregulated in spinal muscular atrophy. Hum Mol Genet 2010; 19:1766-78. [PMID: 20176735 DOI: 10.1093/hmg/ddq058] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinal muscular atrophy (SMA), a motor neuron degeneration disorder, is caused by either mutations or deletions of survival motor neuron 1 (SMN1) gene which result in insufficient SMN protein. Here, we describe a potential link between stathmin and microtubule defects in SMA. Stathmin was identified by screening Smn-knockdown NSC34 cells through proteomics analysis. We found that stathmin was aberrantly upregulated in vitro and in vivo, leading to a decreased level of polymerized tubulin, which was correlated with disease severity. Reduced microtubule densities and beta(III)-tubulin levels in distal axons of affected SMA-like mice and an impaired microtubule network in Smn-deficient cells were observed, suggesting an involvement of stathmin in those microtubule defects. Furthermore, knockdown of stathmin restored the microtubule network defects of Smn-deficient cells, promoted axon outgrowth and reduced the defect in mitochondria transport in SMA-like motor neurons. We conclude that aberrant stathmin levels may play a detrimental role in SMA; this finding suggests a novel approach to treating SMA by enhancing microtubule stability.
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Affiliation(s)
- Hsin-Lan Wen
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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Jin S, Pan L, Liu Z, Wang Q, Xu Z, Zhang YQ. Drosophila Tubulin-specific chaperone E functions at neuromuscular synapses and is required for microtubule network formation. Development 2009; 136:1571-81. [PMID: 19297412 DOI: 10.1242/dev.029983] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hypoparathyroidism, mental retardation and facial dysmorphism (HRD) is a fatal developmental disease caused by mutations in tubulin-specific chaperone E (TBCE). A mouse Tbce mutation causes progressive motor neuronopathy. To dissect the functions of TBCE and the pathogenesis of HRD, we generated mutations in Drosophila tbce, and manipulated its expression in a tissue-specific manner. Drosophila tbce nulls are embryonic lethal. Tissue-specific knockdown and overexpression of tbce in neuromusculature resulted in disrupted and increased microtubules, respectively. Alterations in TBCE expression also affected neuromuscular synapses. Genetic analyses revealed an antagonistic interaction between TBCE and the microtubule-severing protein Spastin. Moreover, treatment of muscles with the microtubule-depolymerizing drug nocodazole implicated TBCE as a tubulin polymerizing protein. Taken together, our results demonstrate that TBCE is required for the normal development and function of neuromuscular synapses and that it promotes microtubule formation. As defective microtubules are implicated in many neurological and developmental diseases, our work on TBCE may offer novel insights into their basis.
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Affiliation(s)
- Shan Jin
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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