1
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Taub DG, Woolf CJ. Age-dependent small fiber neuropathy: Mechanistic insights from animal models. Exp Neurol 2024; 377:114811. [PMID: 38723859 PMCID: PMC11131160 DOI: 10.1016/j.expneurol.2024.114811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/07/2024] [Accepted: 05/05/2024] [Indexed: 05/28/2024]
Abstract
Small fiber neuropathy (SFN) is a common and debilitating disease in which the terminals of small diameter sensory axons degenerate, producing sensory loss, and in many patients neuropathic pain. While a substantial number of cases are attributable to diabetes, almost 50% are idiopathic. An underappreciated aspect of the disease is its late onset in most patients. Animal models of human genetic mutations that produce SFN also display age-dependent phenotypes suggesting that aging is an important contributor to the risk of development of the disease. In this review we define how particular sensory neurons are affected in SFN and discuss how aging may drive the disease. We also evaluate how animal models of SFN can define disease mechanisms that will provide insight into early risk detection and suggest novel therapeutic interventions.
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Affiliation(s)
- Daniel G Taub
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
| | - Clifford J Woolf
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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2
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Wong YC, Jayaraj ND, Belton TB, Shum GC, Ball HE, Ren D, Tadenev ALD, Krainc D, Burgess RW, Menichella DM. Misregulation of mitochondria-lysosome contact dynamics in Charcot-Marie-Tooth Type 2B disease Rab7 mutant sensory peripheral neurons. Proc Natl Acad Sci U S A 2023; 120:e2313010120. [PMID: 37878717 PMCID: PMC10622892 DOI: 10.1073/pnas.2313010120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/12/2023] [Indexed: 10/27/2023] Open
Abstract
Inter-organelle contact sites between mitochondria and lysosomes mediate the crosstalk and bidirectional regulation of their dynamics in health and disease. However, mitochondria-lysosome contact sites and their misregulation have not been investigated in peripheral sensory neurons. Charcot-Marie-Tooth type 2B disease is an autosomal dominant axonal neuropathy affecting peripheral sensory neurons caused by mutations in the GTPase Rab7. Using live super-resolution and confocal time-lapse microscopy, we showed that mitochondria-lysosome contact sites dynamically form in the soma and axons of peripheral sensory neurons. Interestingly, Charcot-Marie-Tooth type 2B mutant Rab7 led to prolonged mitochondria-lysosome contact site tethering preferentially in the axons of peripheral sensory neurons, due to impaired Rab7 GTP hydrolysis-mediated contact site untethering. We further generated a Charcot-Marie-Tooth type 2B mutant Rab7 knock-in mouse model which exhibited prolonged axonal mitochondria-lysosome contact site tethering and defective downstream axonal mitochondrial dynamics due to impaired Rab7 GTP hydrolysis as well as fragmented mitochondria in the axon of the sciatic nerve. Importantly, mutant Rab7 mice further demonstrated preferential sensory behavioral abnormalities and neuropathy, highlighting an important role for mutant Rab7 in driving degeneration of peripheral sensory neurons. Together, this study identifies an important role for mitochondria-lysosome contact sites in the pathogenesis of peripheral neuropathy.
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Affiliation(s)
- Yvette C. Wong
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Nirupa D. Jayaraj
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Tayler B. Belton
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - George C. Shum
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Hannah E. Ball
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Dongjun Ren
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | | | - Dimitri Krainc
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
- Simpson Querrey Center for Neurogenetics, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | | | - Daniela M. Menichella
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
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3
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Mulligan RJ, Winckler B. Regulation of Endosomal Trafficking by Rab7 and Its Effectors in Neurons: Clues from Charcot-Marie-Tooth 2B Disease. Biomolecules 2023; 13:1399. [PMID: 37759799 PMCID: PMC10527268 DOI: 10.3390/biom13091399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 09/09/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Intracellular endosomal trafficking controls the balance between protein degradation and synthesis, i.e., proteostasis, but also many of the cellular signaling pathways that emanate from activated growth factor receptors after endocytosis. Endosomal trafficking, sorting, and motility are coordinated by the activity of small GTPases, including Rab proteins, whose function as molecular switches direct activity at endosomal membranes through effector proteins. Rab7 is particularly important in the coordination of the degradative functions of the pathway. Rab7 effectors control endosomal maturation and the properties of late endosomal and lysosomal compartments, such as coordination of recycling, motility, and fusion with downstream compartments. The spatiotemporal regulation of endosomal receptor trafficking is particularly challenging in neurons because of their enormous size, their distinct intracellular domains with unique requirements (dendrites vs. axons), and their long lifespans as postmitotic, differentiated cells. In Charcot-Marie-Tooth 2B disease (CMT2B), familial missense mutations in Rab7 cause alterations in GTPase cycling and trafficking, leading to an ulcero-mutilating peripheral neuropathy. The prevailing hypothesis to account for CMT2B pathologies is that CMT2B-associated Rab7 alleles alter endocytic trafficking of the neurotrophin NGF and its receptor TrkA and, thereby, disrupt normal trophic signaling in the peripheral nervous system, but other Rab7-dependent pathways are also impacted. Here, using TrkA as a prototypical endocytic cargo, we review physiologic Rab7 effector interactions and control in neurons. Since neurons are among the largest cells in the body, we place particular emphasis on the temporal and spatial regulation of endosomal sorting and trafficking in neuronal processes. We further discuss the current findings in CMT2B mutant Rab7 models, the impact of mutations on effector interactions or balance, and how this dysregulation may confer disease.
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Affiliation(s)
- Ryan J. Mulligan
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
- Medical Scientist Training Program, University of Virginia, Charlottesville, VA 22903, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
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4
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Singh J, Patten SA. Modeling neuromuscular diseases in zebrafish. Front Mol Neurosci 2022; 15:1054573. [PMID: 36583079 PMCID: PMC9794147 DOI: 10.3389/fnmol.2022.1054573] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/21/2022] [Indexed: 12/15/2022] Open
Abstract
Neuromuscular diseases are a diverse group of conditions that affect the motor system and present some overlapping as well as distinct clinical manifestations. Although individually rare, the combined prevalence of NMDs is similar to Parkinson's. Over the past decade, new genetic mutations have been discovered through whole exome/genome sequencing, but the pathogenesis of most NMDs remains largely unexplored. Little information on the molecular mechanism governing the progression and development of NMDs accounts for the continual failure of therapies in clinical trials. Different aspects of the diseases are typically investigated using different models from cells to animals. Zebrafish emerges as an excellent model for studying genetics and pathogenesis and for developing therapeutic interventions for most NMDs. In this review, we describe the generation of different zebrafish genetic models mimicking NMDs and how they are used for drug discovery and therapy development.
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Affiliation(s)
- Jaskaran Singh
- INRS – Centre Armand Frappier Santé Biotechnologie, Laval, QC, Canada
| | - Shunmoogum A. Patten
- INRS – Centre Armand Frappier Santé Biotechnologie, Laval, QC, Canada,Departement de Neurosciences, Université de Montréal, Montréal, QC, Canada,Centre d'Excellence en Recherche sur les Maladies Orphelines – Fondation Courtois (CERMO-FC), Université du Québec à Montréal (UQAM), Montréal, QC, Canada,*Correspondence: Shunmoogum A. Patten,
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5
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Al-Amri AH, Armstrong P, Amici M, Ligneul C, Rouse J, El-Asrag ME, Pantiru A, Vancollie VE, Ng HW, Ogbeta JA, Goodchild K, Ellegood J, Lelliott CJ, Mullins JG, Bretman A, Al-Ali R, Beetz C, Al-Gazali L, Al Shamsi A, Lerch JP, Mellor JR, Al Sayegh A, Ali M, Inglehearn CF, Clapcote SJ. PDZD8 Disruption Causes Cognitive Impairment in Humans, Mice, and Fruit Flies. Biol Psychiatry 2022; 92:323-334. [PMID: 35227461 PMCID: PMC9302898 DOI: 10.1016/j.biopsych.2021.12.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/16/2022]
Abstract
BACKGROUND The discovery of coding variants in genes that confer risk of intellectual disability (ID) is an important step toward understanding the pathophysiology of this common developmental disability. METHODS Homozygosity mapping, whole-exome sequencing, and cosegregation analyses were used to identify gene variants responsible for syndromic ID with autistic features in two independent consanguineous families from the Arabian Peninsula. For in vivo functional studies of the implicated gene's function in cognition, Drosophila melanogaster and mice with targeted interference of the orthologous gene were used. Behavioral, electrophysiological, and structural magnetic resonance imaging analyses were conducted for phenotypic testing. RESULTS Homozygous premature termination codons in PDZD8, encoding an endoplasmic reticulum-anchored lipid transfer protein, showed cosegregation with syndromic ID in both families. Drosophila melanogaster with knockdown of the PDZD8 ortholog exhibited impaired long-term courtship-based memory. Mice homozygous for a premature termination codon in Pdzd8 exhibited brain structural, hippocampal spatial memory, and synaptic plasticity deficits. CONCLUSIONS These data demonstrate the involvement of homozygous loss-of-function mutations in PDZD8 in a neurodevelopmental cognitive disorder. Model organisms with manipulation of the orthologous gene replicate aspects of the human phenotype and suggest plausible pathophysiological mechanisms centered on disrupted brain development and synaptic function. These findings are thus consistent with accruing evidence that synaptic defects are a common denominator of ID and other neurodevelopmental conditions.
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Affiliation(s)
- Ahmed H. Al-Amri
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom,Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom,National Genetic Centre, Royal Hospital, Muscat, Oman
| | - Paul Armstrong
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Mascia Amici
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Clemence Ligneul
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - James Rouse
- School of Biology, University of Leeds, Leeds, United Kingdom
| | - Mohammed E. El-Asrag
- Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom,Department of Zoology, Faculty of Science, Benha University, Benha, Egypt,Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham
| | - Andreea Pantiru
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Hannah W.Y. Ng
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Jennifer A. Ogbeta
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Kirstie Goodchild
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Jacob Ellegood
- Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | | | | | - Amanda Bretman
- School of Biology, University of Leeds, Leeds, United Kingdom
| | | | | | - Lihadh Al-Gazali
- Department of Paediatrics, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Aisha Al Shamsi
- Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
| | - Jason P. Lerch
- Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - Jack R. Mellor
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Abeer Al Sayegh
- Genetics Department, Sultan Qaboos University Hospital, Muscat, Oman
| | - Manir Ali
- Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom
| | - Chris F. Inglehearn
- Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom
| | - Steven J. Clapcote
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom,Address correspondence to Steven J. Clapcote, Ph.D.
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6
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Gu Y, Guerra F, Hu M, Pope A, Sung K, Yang W, Jetha S, Shoff TA, Gunatilake T, Dahlkamp O, Shi LZ, Manganelli F, Nolano M, Zhou Y, Ding J, Bucci C, Wu C. Mitochondria dysfunction in Charcot Marie Tooth 2B Peripheral Sensory Neuropathy. Commun Biol 2022; 5:717. [PMID: 35851620 PMCID: PMC9293960 DOI: 10.1038/s42003-022-03632-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 06/23/2022] [Indexed: 11/21/2022] Open
Abstract
Rab7 GTPase regulates mitochondrial morphology and function. Missense mutation(s) of Rab7 underlies the pathogenesis of Charcot Marie Tooth 2B (CMT2B) peripheral neuropathy. Herein, we investigate how mitochondrial morphology and function are impacted by the CMT2B associated Rab7V162M mutation. In contrast to recent studies of using heterologous overexpression systems, our results demonstrate significant mitochondrial fragmentation in both human CMT2B patient fibroblasts and CMT2B embryonic fibroblasts (MEFs). Primary cultured E18 dorsal root ganglion (DRG) sensory neurons also show mitochondrial fragmentation and altered axonal mitochondrial movement. In addition, we demonstrate that inhibitors to either the mitochondrial fission protein Drp1 or to the nucleotide binding to Rab7 normalize the mitochondrial deficits in both MEFs and E18 cultured DRG neurons. Our study reveals, for the first time, that expression of CMT2B Rab7 mutation at the physiological level enhances Drp1 activity to promote mitochondrial fission, potentially underlying selective vulnerability of peripheral sensory neurons in CMT2B pathogenesis. The Rab7V162M mutation associated with Charcot Marie Tooth 2B peripheral neuropathy causes mitochondrial fragmentation in patient-derived fibroblasts and primary cultured dorsal root ganglion sensory neurons from E18 mouse embryos.
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Affiliation(s)
- Yingli Gu
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA.,Department of Neurology, the Fourth Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, China
| | - Flora Guerra
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), Università del Salento, Via Provinciale Lecce-Monteroni n. 165, 73100, Lecce, Italy
| | - Mingzheng Hu
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA
| | - Alexander Pope
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA
| | - Kijung Sung
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA
| | - Wanlin Yang
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA.,Department of Neurology, Zhujiang Hospital of Southern Medical University Guangzhou, Guangzhou, 510280, Guangdong Sheng, China
| | - Simone Jetha
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA
| | - Thomas A Shoff
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA
| | - Tessanya Gunatilake
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA
| | - Owen Dahlkamp
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA
| | - Linda Zhixia Shi
- Department of Bioengineering, University of California San Diego, La Jolla, 92093, CA, USA
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Via Sergio Pansini 5, 80131, Naples, Italy
| | - Maria Nolano
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Via Sergio Pansini 5, 80131, Naples, Italy
| | - Yue Zhou
- School of Biomedical Engineering, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai, 200030, China
| | - Jianqing Ding
- Institute of Neurology, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), Università del Salento, Via Provinciale Lecce-Monteroni n. 165, 73100, Lecce, Italy.
| | - Chengbiao Wu
- Department of Neurosciences, University of California San Diego, La Jolla, 92093, CA, USA.
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7
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Lischka A, Lassuthova P, Çakar A, Record CJ, Van Lent J, Baets J, Dohrn MF, Senderek J, Lampert A, Bennett DL, Wood JN, Timmerman V, Hornemann T, Auer-Grumbach M, Parman Y, Hübner CA, Elbracht M, Eggermann K, Geoffrey Woods C, Cox JJ, Reilly MM, Kurth I. Genetic pain loss disorders. Nat Rev Dis Primers 2022; 8:41. [PMID: 35710757 DOI: 10.1038/s41572-022-00365-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/10/2022] [Indexed: 01/05/2023]
Abstract
Genetic pain loss includes congenital insensitivity to pain (CIP), hereditary sensory neuropathies and, if autonomic nerves are involved, hereditary sensory and autonomic neuropathy (HSAN). This heterogeneous group of disorders highlights the essential role of nociception in protecting against tissue damage. Patients with genetic pain loss have recurrent injuries, burns and poorly healing wounds as disease hallmarks. CIP and HSAN are caused by pathogenic genetic variants in >20 genes that lead to developmental defects, neurodegeneration or altered neuronal excitability of peripheral damage-sensing neurons. These genetic variants lead to hyperactivity of sodium channels, disturbed haem metabolism, altered clathrin-mediated transport and impaired gene regulatory mechanisms affecting epigenetic marks, long non-coding RNAs and repetitive elements. Therapies for pain loss disorders are mainly symptomatic but the first targeted therapies are being tested. Conversely, chronic pain remains one of the greatest unresolved medical challenges, and the genes and mechanisms associated with pain loss offer new targets for analgesics. Given the progress that has been made, the coming years are promising both in terms of targeted treatments for pain loss disorders and the development of innovative pain medicines based on knowledge of these genetic diseases.
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Affiliation(s)
- Annette Lischka
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Petra Lassuthova
- Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Arman Çakar
- Neuromuscular Unit, Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Christopher J Record
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Jonas Van Lent
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born Bunge, Antwerp, Belgium
| | - Jonathan Baets
- Laboratory of Neuromuscular Pathology, Institute Born Bunge, Antwerp, Belgium.,Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
| | - Maike F Dohrn
- Department of Neurology, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany.,Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Jan Senderek
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
| | - Angelika Lampert
- Institute of Physiology, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - David L Bennett
- Nuffield Department of Clinical Neuroscience, Oxford University, Oxford, UK
| | - John N Wood
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Vincent Timmerman
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born Bunge, Antwerp, Belgium
| | - Thorsten Hornemann
- Department of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Michaela Auer-Grumbach
- Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria
| | - Yesim Parman
- Neuromuscular Unit, Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | | | - Miriam Elbracht
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Katja Eggermann
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - C Geoffrey Woods
- Cambridge Institute for Medical Research, Keith Peters Building, Cambridge Biomedical Campus, Cambridge, UK
| | - James J Cox
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Mary M Reilly
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Ingo Kurth
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany.
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8
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Mitochondria-lysosome contact site dynamics and misregulation in neurodegenerative diseases. Trends Neurosci 2022; 45:312-322. [PMID: 35249745 PMCID: PMC8930467 DOI: 10.1016/j.tins.2022.01.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/11/2022] [Accepted: 01/26/2022] [Indexed: 02/06/2023]
Abstract
Neurons rely heavily on properly regulated mitochondrial and lysosomal homeostasis, with multiple neurodegenerative diseases linked to dysfunction in these two organelles. Interestingly, mitochondria-lysosome membrane contact sites have been identified as a key pathway mediating their crosstalk in neurons. Recent studies have further elucidated the regulation of mitochondria-lysosome contact dynamics via distinct tethering/untethering protein machinery. Moreover, this pathway has been shown to have additional functions in regulating organelle network dynamics and metabolite transfer between lysosomes and mitochondria. In this review, we highlight recent advances in the field of mitochondria-lysosome contact sites and their misregulation across multiple neurodegenerative disorders, which further underscore a potential role for this pathway in neuronal homeostasis and disease.
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9
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Romano R, Del Fiore VS, Saveri P, Palamà IE, Pisciotta C, Pareyson D, Bucci C, Guerra F. Autophagy and Lysosomal Functionality in CMT2B Fibroblasts Carrying the RAB7 K126R Mutation. Cells 2022; 11:cells11030496. [PMID: 35159308 PMCID: PMC8834514 DOI: 10.3390/cells11030496] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/24/2022] [Accepted: 01/27/2022] [Indexed: 01/18/2023] Open
Abstract
Charcot-Marie-Tooth type 2B (CMT2B) disease is a dominant axonal peripheral neuropathy caused by five mutations in the RAB7A gene. Autophagy and late endocytic trafficking were already characterized in CMT2B. Indeed, impairment of autophagy and an increase in lysosomal degradative activity were found in cells expressing the mutant proteins. Recently, we described a novel RAB7 mutation associated with predominantly motor CMT2 and impaired EGFR trafficking. With the aim to analyze the autophagy process and lysosomal activity in CMT2B fibroblasts carrying the p.K126R RAB7 novel mutation and to investigate further the causes of the different phenotype, we have performed Western blot, immunofluorescence and cytometric analyses monitoring autophagic markers and endocytic proteins. Moreover, we investigated lipophagy by analyzing accumulation of lipid droplets and their co-localization with endolysosomal degradative compartments. We found that cells expressing the RAB7K126R mutant protein were characterized by impairment of autophagy and lipophagy processes and by a moderate increase in lysosomal activity compared to the previously studied cells carrying the RAB7V162M mutation. Thus, we concluded that EGFR trafficking alterations and a moderate increase in lysosomal activity with concomitant impairment of autophagy could induce the specific predominantly motor phenotype observed in K126R patients.
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Affiliation(s)
- Roberta Romano
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Provinciale Lecce-Monteroni n. 165, 73100 Lecce, Italy; (R.R.); (V.S.D.F.)
| | - Victoria Stefania Del Fiore
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Provinciale Lecce-Monteroni n. 165, 73100 Lecce, Italy; (R.R.); (V.S.D.F.)
| | - Paola Saveri
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy; (P.S.); (C.P.); (D.P.)
| | | | - Chiara Pisciotta
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy; (P.S.); (C.P.); (D.P.)
| | - Davide Pareyson
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy; (P.S.); (C.P.); (D.P.)
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Provinciale Lecce-Monteroni n. 165, 73100 Lecce, Italy; (R.R.); (V.S.D.F.)
- Correspondence: (C.B.); (F.G.); Tel.: +39-08-3229-8900 (C.B.)
| | - Flora Guerra
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Provinciale Lecce-Monteroni n. 165, 73100 Lecce, Italy; (R.R.); (V.S.D.F.)
- Correspondence: (C.B.); (F.G.); Tel.: +39-08-3229-8900 (C.B.)
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10
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Tzou FY, Wen JK, Yeh JY, Huang SY, Chen GC, Chan CC. Drosophila as a model to study autophagy in neurodegenerative diseases and digestive tract. IUBMB Life 2021; 74:339-360. [PMID: 34874101 DOI: 10.1002/iub.2583] [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: 10/10/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 12/20/2022]
Abstract
Autophagy regulates cellular homeostasis by degrading and recycling cytosolic components and damaged organelles. Disruption of autophagic flux has been shown to induce or facilitate neurodegeneration and accumulation of autophagic vesicles is overt in neurodegenerative diseases. The fruit fly Drosophila has been used as a model system to identify new factors that regulate physiology and disease. Here we provide a historical perspective of how the fly models have offered mechanistic evidence to understand the role of autophagy in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Charcot-Marie-Tooth neuropathy, and polyglutamine disorders. Autophagy also plays a pivotal role in maintaining tissue homeostasis and protecting organism health. The gastrointestinal tract regulates organism health by modulating food intake, energy balance, and immunity. Growing evidence is strengthening the link between autophagy and digestive tract health in recent years. Here, we also discuss how the fly models have advanced the understanding of digestive physiology regulated by autophagy.
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Affiliation(s)
- Fei-Yang Tzou
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Jung-Kun Wen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Jui-Yu Yeh
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Shu-Yi Huang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Guang-Chao Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
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11
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Markworth R, Dambeck V, Steinbeck LM, Koufali A, Bues B, Dankovich TM, Wichmann C, Burk K. Tubular microdomains of Rab7-positive endosomes retrieve TrkA, a mechanism disrupted in Charcot-Marie-Tooth disease 2B. J Cell Sci 2021; 134:272650. [PMID: 34486665 DOI: 10.1242/jcs.258559] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 08/23/2021] [Indexed: 01/04/2023] Open
Abstract
Axonal survival and growth requires signalling from tropomyosin receptor kinases (Trks). To transmit their signals, receptor-ligand complexes are endocytosed and undergo retrograde trafficking to the soma, where downstream signalling occurs. Vesicles transporting neurotrophic receptors to the soma are reported to be Rab7-positive late endosomes and/or multivesicular bodies (MVBs), where receptors localize within so-called intraluminal vesicles (herein Rab7 corresponds to Rab7A unless specified otherwise). Therefore, one challenging question is how downstream signalling is possible given the insulating properties of intraluminal vesicles. In this study, we report that Rab7-positive endosomes and MVBs retrieve TrkA (also known as NTRK1) through tubular microdomains. Interestingly, this phenotype is absent for the EGF receptor. Furthermore, we found that endophilinA1, endophilinA2 and endophilinA3, together with WASH1 (also known as WASHC1), are involved in the tubulation process. In Charcot-Marie-Tooth disease 2B (CMT2B), a neuropathy of the peripheral nervous system, this tubulating mechanism is disrupted. In addition, the ability to tubulate correlates with the phosphorylation levels of TrkA as well as with neurite length in neuronal cultures from dorsal root ganglia. In all, we report a new retrieval mechanism of late Rab7-positive endosomes, which enables TrkA signalling and sheds new light onto how neurotrophic signalling is disrupted in CMT2B. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Ronja Markworth
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,European Neuroscience Institute, Grisebachstraße 5, 37077 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Vivian Dambeck
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Lars Malte Steinbeck
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Angeliki Koufali
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Bastian Bues
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Tal M Dankovich
- Institute for Neuro- and Sensory Physiology, Humboldtallee 23, 37073 Göttingen, Germany
| | - Carolin Wichmann
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany.,Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Centers 889 'Cellular Mechanisms of Sensory Processing' and 1286 'Quantitative Synaptology', 37099 Göttingen, Germany
| | - Katja Burk
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,European Neuroscience Institute, Grisebachstraße 5, 37077 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
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12
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Hornemann T. Mini review: Lipids in Peripheral Nerve Disorders. Neurosci Lett 2020; 740:135455. [PMID: 33166639 DOI: 10.1016/j.neulet.2020.135455] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/25/2020] [Accepted: 09/27/2020] [Indexed: 02/06/2023]
Abstract
Neurons are polarized cells whose fundamental functions are to receive, conduct and transmit signals. In bilateral animals, the nervous system is divided into the central (CNS) and peripheral (PNS) nervous system. The main function of the PNS is to connect the CNS to the limbs and organs, essentially serving as a relay between the brain and spinal cord and the rest of the body. Sensory axons can be up to 3 feet in length. Because of its long-reaching and complex structure, the peripheral nervous system (PNS) is exposed and vulnerable to many genetic, metabolic and environmental predispositions. Lipids and lipid intermediates are essential components of nerves. About 50 % of the brain dry weight consist of lipids, which makes it the second highest lipid rich tissue after adipose tissue. However, the role of lipids in neurological disorders in particular of the peripheral nerves is not well understood. This review aims to provide an overview about the role of lipids in the disorders of the PNS.
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Affiliation(s)
- Th Hornemann
- Institute for Clinical Chemistry, University Hospital and University Zurich, 8091, Zürich, Switzerland.
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13
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Tamargo-Gómez I, Fernández ÁF, Mariño G. Pathogenic Single Nucleotide Polymorphisms on Autophagy-Related Genes. Int J Mol Sci 2020; 21:ijms21218196. [PMID: 33147747 PMCID: PMC7672651 DOI: 10.3390/ijms21218196] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 02/06/2023] Open
Abstract
In recent years, the study of single nucleotide polymorphisms (SNPs) has gained increasing importance in biomedical research, as they can either be at the molecular origin of a determined disorder or directly affect the efficiency of a given treatment. In this regard, sequence variations in genes involved in pro-survival cellular pathways are commonly associated with pathologies, as the alteration of these routes compromises cellular homeostasis. This is the case of autophagy, an evolutionarily conserved pathway that counteracts extracellular and intracellular stressors by mediating the turnover of cytosolic components through lysosomal degradation. Accordingly, autophagy dysregulation has been extensively described in a wide range of human pathologies, including cancer, neurodegeneration, or inflammatory alterations. Thus, it is not surprising that pathogenic gene variants in genes encoding crucial effectors of the autophagosome/lysosome axis are increasingly being identified. In this review, we present a comprehensive list of clinically relevant SNPs in autophagy-related genes, highlighting the scope and relevance of autophagy alterations in human disease.
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Affiliation(s)
- Isaac Tamargo-Gómez
- Instituto de Investigación Sanitaria del Principado de Asturias, 33011 Oviedo, Spain;
- Departamento de Biología Funcional, Universidad de Oviedo, 33011 Oviedo, Spain
| | - Álvaro F. Fernández
- Instituto de Investigación Sanitaria del Principado de Asturias, 33011 Oviedo, Spain;
- Departamento de Biología Funcional, Universidad de Oviedo, 33011 Oviedo, Spain
- Correspondence: (Á.F.F.); (G.M.); Tel.: +34-985652416 (G.M.)
| | - Guillermo Mariño
- Instituto de Investigación Sanitaria del Principado de Asturias, 33011 Oviedo, Spain;
- Departamento de Biología Funcional, Universidad de Oviedo, 33011 Oviedo, Spain
- Correspondence: (Á.F.F.); (G.M.); Tel.: +34-985652416 (G.M.)
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14
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Longo F, Benedetti S, Zambon AA, Sora MGN, Di Resta C, De Ritis D, Quattrini A, Maltecca F, Ferrari M, Previtali SC. Impaired turnover of hyperfused mitochondria in severe axonal neuropathy due to a novel DRP1 mutation. Hum Mol Genet 2020; 29:177-188. [PMID: 31868880 DOI: 10.1093/hmg/ddz211] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 08/09/2019] [Accepted: 08/28/2019] [Indexed: 12/09/2022] Open
Abstract
Mitochondria undergo continuous cycles of fusion and fission in response to physiopathological stimuli. The key player in mitochondrial fission is dynamin-related protein 1 (DRP1), a cytosolic protein encoded by dynamin 1-like (DNM1L) gene, which relocalizes to the outer mitochondrial membrane, where it assembles, oligomerizes and drives mitochondrial division upon guanosine-5'-triphosphate (GTP) hydrolysis. Few DRP1 mutations have been described so far, with patients showing complex and variable phenotype ranging from early death to encephalopathy and/or optic atrophy. The disease is the consequence of defective mitochondrial fission due to faulty DRP1 function. However, the underlying molecular mechanisms and the functional consequences at mitochondrial and cellular level remain elusive. Here we report on a 5-year-old girl presenting psychomotor developmental delay, global hypotonia and severe ataxia due to axonal sensory neuropathy harboring a novel de novo heterozygous missense mutation in the GTPase domain of DRP1 (NM_012062.3:c.436G>A, NP_036192.2: p.D146N variant in DNM1L). Patient's fibroblasts show hyperfused/balloon-like giant mitochondria, highlighting the importance of D146 residue for DRP1 function. This dramatic mitochondrial rearrangement phenocopies what observed overexpressing DRP1-K38A, a well-known experimental dominant negative version of DRP1. In addition, we demonstrated that p.D146N mutation has great impact on peroxisomal shape and function. The p.D146N mutation compromises the GTPase activity without perturbing DRP1 recruitment or assembly, causing decreased mitochondrial and peroxisomal turnover. In conclusion, our findings highlight the importance of sensory neuropathy in the clinical spectrum of DRP1 variants and, for the first time, the impact of DRP1 mutations on mitochondrial turnover and peroxisomal functionality.
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Affiliation(s)
- Fabiana Longo
- Neurogenomics Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Sara Benedetti
- Laboratory of Clinical Molecular Biology and Cytogenetics, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Alberto A Zambon
- Department of Neurology, IRCCS Ospedale San Raffaele, Milan, Italy
| | | | - Chiara Di Resta
- Università Vita-Salute San Raffaele, Milan, Italy.,Genomic Unit for the Diagnosis of Human Pathologies, Division of Genetics and Cellular Biology IRCCS Ospedale San Raffaele, Milan, Italy
| | - Daniele De Ritis
- Neurogenomics Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Angelo Quattrini
- Department of Neurology, IRCCS Ospedale San Raffaele, Milan, Italy.,Inspe and Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Francesca Maltecca
- Neurogenomics Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
| | - Maurizio Ferrari
- Laboratory of Clinical Molecular Biology and Cytogenetics, IRCCS Ospedale San Raffaele, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy.,Genomic Unit for the Diagnosis of Human Pathologies, Division of Genetics and Cellular Biology IRCCS Ospedale San Raffaele, Milan, Italy
| | - Stefano Carlo Previtali
- Department of Neurology, IRCCS Ospedale San Raffaele, Milan, Italy.,Inspe and Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
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15
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Giudetti AM, Guerra F, Longo S, Beli R, Romano R, Manganelli F, Nolano M, Mangini V, Santoro L, Bucci C. An altered lipid metabolism characterizes Charcot-Marie-Tooth type 2B peripheral neuropathy. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158805. [PMID: 32829064 DOI: 10.1016/j.bbalip.2020.158805] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 07/20/2020] [Accepted: 08/17/2020] [Indexed: 12/12/2022]
Abstract
Charcot-Marie Tooth type 2B (CMT2B) is a rare inherited peripheral neuropathy caused by five missense mutations in the RAB7A gene, which encodes a small GTPase of the RAB family. Currently, no cure is available for this disease. In this study, we approached the disease by comparing the lipid metabolism of CMT2B-derived fibroblasts to that of healthy controls. We found that CMT2B cells showed increased monounsaturated fatty acid level and increased expression of key enzymes of monounsaturated and polyunsaturated fatty acid synthesis. Moreover, in CMT2B cells a higher expression of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), key enzymes of de novo fatty acid synthesis, with a concomitantly increased [1-14C]acetate incorporation into fatty acids, was observed. The expression of diacylglycerol acyltransferase 2, a rate-limiting enzyme in triacylglycerol synthesis, as well as triacylglycerol levels were increased in CMT2B compared to control cells. In addition, as RAB7A controls lipid droplet breakdown and lipid droplet dynamics have been linked to diseases, we analyzed these organelles and showed that in CMT2B cells there is a strong accumulation of lipid droplets compared to control cells, thus reinforcing our data on abnormal lipid metabolism in CMT2B. Furthermore, we demonstrated that ACC and FAS expression levels changed upon RAB7 silencing or overexpression in HeLa cells, thus suggesting that metabolic modifications observed in CMT2B-derived fibroblasts can be, at least in part, related to RAB7 mutations.
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Affiliation(s)
- Anna Maria Giudetti
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Monteroni n. 165, 73100 Lecce, Italy.
| | - Flora Guerra
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Monteroni n. 165, 73100 Lecce, Italy
| | - Serena Longo
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Monteroni n. 165, 73100 Lecce, Italy
| | - Raffaella Beli
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Monteroni n. 165, 73100 Lecce, Italy
| | - Roberta Romano
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Monteroni n. 165, 73100 Lecce, Italy
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Via Sergio Pansini 5, 80131, Naples, Italy
| | - Maria Nolano
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Via Sergio Pansini 5, 80131, Naples, Italy; Istituti Clinici Scientifici Maugeri IRCCS, Department of Neurology of Telese Terme Institute, 82037 Telese Terme, Benevento, Italy
| | - Vincenzo Mangini
- Center for Biomolecular Nanotechnologies@UniLe, Istituto Italiano di Tecnologia, 73010 Arnesano (LE), Italy
| | - Lucio Santoro
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Via Sergio Pansini 5, 80131, Naples, Italy
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Monteroni n. 165, 73100 Lecce, Italy.
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16
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Rivero-Ríos P, Romo-Lozano M, Fasiczka R, Naaldijk Y, Hilfiker S. LRRK2-Related Parkinson's Disease Due to Altered Endolysosomal Biology With Variable Lewy Body Pathology: A Hypothesis. Front Neurosci 2020; 14:556. [PMID: 32581693 PMCID: PMC7287096 DOI: 10.3389/fnins.2020.00556] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 05/06/2020] [Indexed: 12/14/2022] Open
Abstract
Mutations in the gene encoding for leucine-rich repeat kinase 2 (LRRK2) are associated with both familial and sporadic Parkinson's disease (PD). LRRK2 encodes a large protein comprised of a GTPase and a kinase domain. All pathogenic variants converge on enhancing LRRK2 kinase substrate phosphorylation, and distinct LRRK2 kinase inhibitors are currently in various stages of clinical trials. Although the precise pathophysiological functions of LRRK2 remain largely unknown, PD-associated mutants have been shown to alter various intracellular vesicular trafficking pathways, especially those related to endolysosomal protein degradation events. In addition, biochemical studies have identified a subset of Rab proteins, small GTPases required for all vesicular trafficking steps, as substrate proteins for the LRRK2 kinase activity in vitro and in vivo. Therefore, it is crucial to evaluate the impact of such phosphorylation on neurodegenerative mechanisms underlying LRRK2-related PD, especially with respect to deregulated Rab-mediated endolysosomal membrane trafficking and protein degradation events. Surprisingly, a significant proportion of PD patients due to LRRK2 mutations display neuronal cell loss in the substantia nigra pars compacta in the absence of any apparent α-synuclein-containing Lewy body neuropathology. These findings suggest that endolysosomal alterations mediated by pathogenic LRRK2 per se are not sufficient to cause α-synuclein aggregation. Here, we will review current knowledge about the link between pathogenic LRRK2, Rab protein phosphorylation and endolysosomal trafficking alterations, and we will propose a testable working model whereby LRRK2-related PD may present with variable LB pathology.
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Affiliation(s)
- Pilar Rivero-Ríos
- Institute of Parasitology and Biomedicine "López-Neyra", Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, United States
| | - María Romo-Lozano
- Institute of Parasitology and Biomedicine "López-Neyra", Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Rachel Fasiczka
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Yahaira Naaldijk
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Sabine Hilfiker
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
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17
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Fraiberg M, Elazar Z. Genetic defects of autophagy linked to disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 172:293-323. [PMID: 32620246 DOI: 10.1016/bs.pmbts.2020.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Autophagy is a highly conserved lysosomal degradation pathway responsible for rapid elimination of unwanted cytoplasmic materials in response to stressful conditions. This cytoprotective function is essential for maintenance of cellular homeostasis and is mediated by conserved autophagy-related genes (ATG) and autophagic receptors. Impairment of autophagy frequently results in a wide variety of human pathologies. Recent studies have revealed direct links between diverse diseases and genetic defects of core autophagy genes, autophagy-associated genes, and genes encoding autophagic receptors. Here we provide a general description of autophagy-related genes and their mutations or polymorphisms that play a causative role in specific human disorders or may be risk factors for them.
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Affiliation(s)
- Milana Fraiberg
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel.
| | - Zvulun Elazar
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel.
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18
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Charcot-Marie-Tooth Type 2B: A New Phenotype Associated with a Novel RAB7A Mutation and Inhibited EGFR Degradation. Cells 2020; 9:cells9041028. [PMID: 32326241 PMCID: PMC7226405 DOI: 10.3390/cells9041028] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 01/01/2023] Open
Abstract
The rare autosomal dominant Charcot-Marie-Tooth type 2B (CMT2B) is associated with mutations in the RAB7A gene, involved in the late endocytic pathway. CMT2B is characterized by predominant sensory loss, ulceromutilating features, with lesser-to-absent motor deficits. We characterized clinically and genetically a family harboring a novel pathogenic RAB7A variant and performed structural and functional analysis of the mutant protein. A 39-year-old woman presented with early-onset walking difficulties, progressive distal muscle wasting and weakness in lower limbs and only mild sensory signs. Electrophysiology demonstrated an axonal sensorimotor neuropathy. Nerve biopsy showed a chronic axonal neuropathy with moderate loss of all caliber myelinated fibers. Next-generation sequencing (NGS) technology revealed in the proband and in her similarly affected father the novel c.377A>G (p.K126R) heterozygous variant predicted to be deleterious. The mutation affects the biochemical properties of RAB7 GTPase, causes altered interaction with peripherin, and inhibition of neurite outgrowth, as for previously reported CMT2B mutants. However, it also shows differences, particularly in the epidermal growth factor receptor degradation process. Altogether, our findings indicate that this RAB7A variant is pathogenic and widens the phenotypic spectrum of CMT2B to include predominantly motor CMT2. Alteration of the receptor degradation process might explain the different clinical presentations in this family.
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19
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Romano R, Rivellini C, De Luca M, Tonlorenzi R, Beli R, Manganelli F, Nolano M, Santoro L, Eskelinen EL, Previtali SC, Bucci C. Alteration of the late endocytic pathway in Charcot-Marie-Tooth type 2B disease. Cell Mol Life Sci 2020; 78:351-372. [PMID: 32280996 PMCID: PMC7867545 DOI: 10.1007/s00018-020-03510-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/18/2020] [Accepted: 03/24/2020] [Indexed: 12/18/2022]
Abstract
The small GTPase RAB7A regulates late stages of the endocytic pathway and plays specific roles in neurons, controlling neurotrophins trafficking and signaling, neurite outgrowth and neuronal migration. Mutations in the RAB7A gene cause the autosomal dominant Charcot–Marie–Tooth type 2B (CMT2B) disease, an axonal peripheral neuropathy. As several neurodegenerative diseases are caused by alterations of endocytosis, we investigated whether CMT2B-causing mutations correlate with changes in this process. To this purpose, we studied the endocytic pathway in skin fibroblasts from healthy and CMT2B individuals. We found higher expression of late endocytic proteins in CMT2B cells compared to control cells, as well as higher activity of cathepsins and higher receptor degradation activity. Consistently, we observed an increased number of lysosomes, accompanied by higher lysosomal degradative activity in CMT2B cells. Furthermore, we found increased migration and increased RAC1 and MMP-2 activation in CMT2B compared to control cells. To validate these data, we obtained sensory neurons from patient and control iPS cells, to confirm increased lysosomal protein expression and lysosomal activity in CMT2B-derived neurons. Altogether, these results demonstrate that in CMT2B patient-derived cells, the endocytic degradative pathway is altered, suggesting that higher lysosomal activity contributes to neurodegeneration occurring in CMT2B.
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Affiliation(s)
- Roberta Romano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy
| | - Cristina Rivellini
- Institute of Experimental Neurology (INSPE), IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maria De Luca
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy
| | - Rossana Tonlorenzi
- Institute of Experimental Neurology (INSPE), IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Raffaella Beli
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | - Maria Nolano
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
- Salvatore Maugeri Foundation, Institute of Telese Terme, Benevento, Italy
| | - Lucio Santoro
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | - Eeva-Liisa Eskelinen
- Institute of Biomedicine, University of Turku, Turku, Finland
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
| | - Stefano C Previtali
- Institute of Experimental Neurology (INSPE), IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy.
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20
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Sironi L, Restelli LM, Tolnay M, Neutzner A, Frank S. Dysregulated Interorganellar Crosstalk of Mitochondria in the Pathogenesis of Parkinson's Disease. Cells 2020; 9:cells9010233. [PMID: 31963435 PMCID: PMC7016713 DOI: 10.3390/cells9010233] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 12/11/2022] Open
Abstract
The pathogenesis of Parkinson’s disease (PD), the second most common neurodegenerative disorder, is complex and involves the impairment of crucial intracellular physiological processes. Importantly, in addition to abnormal α-synuclein aggregation, the dysfunction of various mitochondria-dependent processes has been prominently implicated in PD pathogenesis. Besides the long-known loss of the organelles’ bioenergetics function resulting in diminished ATP synthesis, more recent studies in the field have increasingly focused on compromised mitochondrial quality control as well as impaired biochemical processes specifically localized to ER–mitochondria interfaces (such as lipid biosynthesis and calcium homeostasis). In this review, we will discuss how dysregulated mitochondrial crosstalk with other organelles contributes to PD pathogenesis.
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Affiliation(s)
- Lara Sironi
- Division of Neuropathology, Institute of Medical Genetics and Pathology, University Hospital Basel, 4031 Basel, Switzerland; (L.M.R.); (M.T.)
- Correspondence: (L.S.); (S.F.); Tel.: +41-61-265-2776 (L.S. & S.F.)
| | - Lisa Michelle Restelli
- Division of Neuropathology, Institute of Medical Genetics and Pathology, University Hospital Basel, 4031 Basel, Switzerland; (L.M.R.); (M.T.)
| | - Markus Tolnay
- Division of Neuropathology, Institute of Medical Genetics and Pathology, University Hospital Basel, 4031 Basel, Switzerland; (L.M.R.); (M.T.)
| | - Albert Neutzner
- Department of Biomedicine, University Hospital Basel, University of Basel, 4031 Basel, Switzerland;
- Department of Ophthalmology University Hospital Basel, University of Basel, 4031 Basel, Switzerland
| | - Stephan Frank
- Division of Neuropathology, Institute of Medical Genetics and Pathology, University Hospital Basel, 4031 Basel, Switzerland; (L.M.R.); (M.T.)
- Correspondence: (L.S.); (S.F.); Tel.: +41-61-265-2776 (L.S. & S.F.)
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21
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Rab GTPases: Switching to Human Diseases. Cells 2019; 8:cells8080909. [PMID: 31426400 PMCID: PMC6721686 DOI: 10.3390/cells8080909] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 02/07/2023] Open
Abstract
Rab proteins compose the largest family of small GTPases and control the different steps of intracellular membrane traffic. More recently, they have been shown to also regulate cell signaling, division, survival, and migration. The regulation of these processes generally occurs through recruitment of effectors and regulatory proteins, which control the association of Rab proteins to membranes and their activation state. Alterations in Rab proteins and their effectors are associated with multiple human diseases, including neurodegeneration, cancer, and infections. This review provides an overview of how the dysregulation of Rab-mediated functions and membrane trafficking contributes to these disorders. Understanding the altered dynamics of Rabs and intracellular transport defects might thus shed new light on potential therapeutic strategies.
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Guerra F, Bucci C. Role of the RAB7 Protein in Tumor Progression and Cisplatin Chemoresistance. Cancers (Basel) 2019; 11:cancers11081096. [PMID: 31374919 PMCID: PMC6721790 DOI: 10.3390/cancers11081096] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/23/2019] [Accepted: 07/30/2019] [Indexed: 12/19/2022] Open
Abstract
RAB7 is a small guanosine triphosphatase (GTPase) extensively studied as regulator of vesicular trafficking. Indeed, its role is fundamental in several steps of the late endocytic pathway, including endosome maturation, transport from early endosomes to late endosomes and lysosomes, clustering and fusion of late endosomes and lysosomes in the perinuclear region and lysosomal biogenesis. Besides endocytosis, RAB7 is important for a number of other cellular processes among which, autophagy, apoptosis, signaling, and cell migration. Given the importance of RAB7 in these cellular processes, the interest to study the role of RAB7 in cancer progression is widely grown. Here, we describe the current understanding of oncogenic and oncosuppressor functions of RAB7 analyzing cellular context and other environmental factors in which it elicits pro and/or antitumorigenic effects. We also discuss the role of RAB7 in cisplatin resistance associated with its ability to regulate the late endosomal pathway, lysosomal biogenesis and extracellular vesicle secretion. Finally, we examined the potential cancer therapeutic strategies targeting the different molecular events in which RAB7 is involved.
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Affiliation(s)
- Flora Guerra
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via Provinciale Lecce-Monteroni 165, 73100 Lecce, Italy.
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via Provinciale Lecce-Monteroni 165, 73100 Lecce, Italy.
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Wong YC, Peng W, Krainc D. Lysosomal Regulation of Inter-mitochondrial Contact Fate and Motility in Charcot-Marie-Tooth Type 2. Dev Cell 2019; 50:339-354.e4. [PMID: 31231042 DOI: 10.1016/j.devcel.2019.05.033] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 02/25/2019] [Accepted: 05/16/2019] [Indexed: 10/26/2022]
Abstract
Properly regulated mitochondrial networks are essential for cellular function and implicated in multiple diseases. Mitochondria undergo fission and fusion events, but the dynamics and regulation of a third event of inter-mitochondrial contact formation remain unclear. Using super-resolution imaging, we demonstrate that inter-mitochondrial contacts frequently form and play a fundamental role in mitochondrial networks by restricting mitochondrial motility. Inter-mitochondrial contact untethering events are marked and regulated by mitochondria-lysosome contacts, which are modulated by RAB7 GTP hydrolysis. Moreover, inter-mitochondrial contact formation and untethering are further regulated by Mfn1/2 and Drp1 GTP hydrolysis, respectively. Surprisingly, endoplasmic reticulum tubules are also present at inter-mitochondrial contact untethering events, in addition to mitochondrial fission and fusion events. Importantly, we find that multiple Charcot-Marie-Tooth type 2 disease-linked mutations in Mfn2 (CMT2A), RAB7 (CMT2B), and TRPV4 (CMT2C) converge on prolonged inter-mitochondrial contacts and defective mitochondrial motility, highlighting a role for inter-mitochondrial contacts in mitochondrial network regulation and disease.
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Affiliation(s)
- Yvette C Wong
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Wesley Peng
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Dimitri Krainc
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Wong YC, Kim S, Peng W, Krainc D. Regulation and Function of Mitochondria-Lysosome Membrane Contact Sites in Cellular Homeostasis. Trends Cell Biol 2019; 29:500-513. [PMID: 30898429 DOI: 10.1016/j.tcb.2019.02.004] [Citation(s) in RCA: 180] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/04/2019] [Accepted: 02/08/2019] [Indexed: 12/18/2022]
Abstract
Mitochondrial and lysosomal function are intricately related and critical for maintaining cellular homeostasis, as highlighted by multiple diseases linked to dysfunction of both organelles. Recent work using high-resolution microscopy demonstrates the dynamic formation of inter-organelle membrane contact sites between mitochondria and lysosomes, allowing for their direct interaction in a pathway distinct from mitophagy or lysosomal degradation of mitochondrial-derived vesicles. Mitochondria-lysosome contact site tethering is mechanistically regulated by mitochondrial proteins promoting Rab7 GTP hydrolysis, and allows for the bidirectional crosstalk between mitochondria and lysosomes and the regulation of their organelle network dynamics, including mitochondrial fission. In this review, we summarize recent advances in mitochondria-lysosome contact site regulation and function, and discuss their potential roles in cellular homeostasis and various human diseases.
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Affiliation(s)
- Yvette C Wong
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Soojin Kim
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Wesley Peng
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Dimitri Krainc
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Cioni JM, Lin JQ, Holtermann AV, Koppers M, Jakobs MAH, Azizi A, Turner-Bridger B, Shigeoka T, Franze K, Harris WA, Holt CE. Late Endosomes Act as mRNA Translation Platforms and Sustain Mitochondria in Axons. Cell 2019; 176:56-72.e15. [PMID: 30612743 PMCID: PMC6333918 DOI: 10.1016/j.cell.2018.11.030] [Citation(s) in RCA: 253] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 09/10/2018] [Accepted: 11/18/2018] [Indexed: 12/14/2022]
Abstract
Local translation regulates the axonal proteome, playing an important role in neuronal wiring and axon maintenance. How axonal mRNAs are localized to specific subcellular sites for translation, however, is not understood. Here we report that RNA granules associate with endosomes along the axons of retinal ganglion cells. RNA-bearing Rab7a late endosomes also associate with ribosomes, and real-time translation imaging reveals that they are sites of local protein synthesis. We show that RNA-bearing late endosomes often pause on mitochondria and that mRNAs encoding proteins for mitochondrial function are translated on Rab7a endosomes. Disruption of Rab7a function with Rab7a mutants, including those associated with Charcot-Marie-Tooth type 2B neuropathy, markedly decreases axonal protein synthesis, impairs mitochondrial function, and compromises axonal viability. Our findings thus reveal that late endosomes interact with RNA granules, translation machinery, and mitochondria and suggest that they serve as sites for regulating the supply of nascent pro-survival proteins in axons. Ribonucleoprotein particles are associated with endosomes in axons Rab7a endosomes provide sites for axonal local translation Rab7a endosomes support axonal synthesis of survival factors CMT2B-Rab7a mutations affect axonal translation and mitochondrial integrity
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Affiliation(s)
- Jean-Michel Cioni
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Julie Qiaojin Lin
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Anne V Holtermann
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Max Koppers
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Maximilian A H Jakobs
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Afnan Azizi
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Benita Turner-Bridger
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Toshiaki Shigeoka
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - William A Harris
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
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Wu R, Fu J, Meng L, Lv H, Wang Z, Yuan Y. Late-onset hereditary sensory and autonomic neuropathy expands the phenotypic spectrum of MFN2-related diseases. Neuropathology 2018; 38:463-467. [PMID: 30011089 DOI: 10.1111/neup.12487] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/05/2018] [Accepted: 06/04/2018] [Indexed: 12/22/2022]
Abstract
Mutations in the Mitofusin 2 (MFN2) gene have been identified in patients with autosomal dominant axonal motor and sensory neuropathy or Charcot-Marie-Tooth 2A (CMT2A). Here we describe clinical and pathological changes in an adult patient with sporadic hereditary sensory and autonomic neuropathy (HSAN) due to an MFN2 mutation. The patient was a 53-year-old man who had sensory involvement and anhidrosis in all limbs without motor features. The electrophysiological assessment documented severe axonal sensory neuropathy. The sural nerve biopsy confirmed the electrophysiological findings, revealing severe loss of myelinated and unmyelinated fibers with regeneration clusters. Genetic analysis revealed the previously identified mutation c.776 G > A in MFN2. Our report expands the phenotypic spectrum of MFN2-related diseases. Sequencing of MFN2 should be considered in all patients presenting with late-onset HSAN.
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Affiliation(s)
- Rui Wu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Jun Fu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Lingchao Meng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - He Lv
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
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Colecchia D, Stasi M, Leonardi M, Manganelli F, Nolano M, Veneziani BM, Santoro L, Eskelinen EL, Chiariello M, Bucci C. Alterations of autophagy in the peripheral neuropathy Charcot-Marie-Tooth type 2B. Autophagy 2018; 14:930-941. [PMID: 29130394 PMCID: PMC6103410 DOI: 10.1080/15548627.2017.1388475] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Charcot-Marie-Tooth type 2B (CMT2B) disease is a dominant axonal peripheral neuropathy caused by 5 mutations in the RAB7A gene, a ubiquitously expressed GTPase controlling late endocytic trafficking. In neurons, RAB7A also controls neuronal-specific processes such as NTF (neurotrophin) trafficking and signaling, neurite outgrowth and neuronal migration. Given the involvement of macroautophagy/autophagy in several neurodegenerative diseases and considering that RAB7A is fundamental for autophagosome maturation, we investigated whether CMT2B-causing mutants affect the ability of this gene to regulate autophagy. In HeLa cells, we observed a reduced localization of all CMT2B-causing RAB7A mutants on autophagic compartments. Furthermore, compared to expression of RAB7AWT, expression of these mutants caused a reduced autophagic flux, similar to what happens in cells expressing the dominant negative RAB7AT22N mutant. Consistently, both basal and starvation-induced autophagy were strongly inhibited in skin fibroblasts from a CMT2B patient carrying the RAB7AV162M mutation, suggesting that alteration of the autophagic flux could be responsible for neurodegeneration.
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Affiliation(s)
- David Colecchia
- a Consiglio Nazionale delle Ricerche, Istituto di Fisiologia Clinica and Istituto Toscano Tumori-Core Research Laboratory , Signal Transduction Unit , AOU Senese , Siena , Italy
| | - Mariangela Stasi
- b Department of Biological and Environmental Sciences and Technologies (DiSTeBA) , University of Salento , Lecce , Italy
| | - Margherita Leonardi
- a Consiglio Nazionale delle Ricerche, Istituto di Fisiologia Clinica and Istituto Toscano Tumori-Core Research Laboratory , Signal Transduction Unit , AOU Senese , Siena , Italy
| | - Fiore Manganelli
- c Department of Neurosciences , University of Naples "Federico II" , Naples , Italy
| | - Maria Nolano
- d Salvatore Maugeri Foundation , Institute of Telese Terme , Benevento , Italy
| | - Bianca Maria Veneziani
- e Department of Molecular Medicine and Medical Biotechnologies , University of Naples "Federico II" , Naples , Italy
| | - Lucio Santoro
- c Department of Neurosciences , University of Naples "Federico II" , Naples , Italy
| | - Eeva-Liisa Eskelinen
- f Department of Biosciences, Division of Biochemistry and Biotechnology , University of Helsinki , Helsinki , Finland
| | - Mario Chiariello
- a Consiglio Nazionale delle Ricerche, Istituto di Fisiologia Clinica and Istituto Toscano Tumori-Core Research Laboratory , Signal Transduction Unit , AOU Senese , Siena , Italy
| | - Cecilia Bucci
- b Department of Biological and Environmental Sciences and Technologies (DiSTeBA) , University of Salento , Lecce , Italy
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Gao Y, Wilson GR, Stephenson SEM, Bozaoglu K, Farrer MJ, Lockhart PJ. The emerging role of Rab GTPases in the pathogenesis of Parkinson's disease. Mov Disord 2018; 33:196-207. [DOI: 10.1002/mds.27270] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 11/16/2017] [Accepted: 11/19/2017] [Indexed: 12/30/2022] Open
Affiliation(s)
- Yujing Gao
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute; Melbourne Victoria Australia
- Department of Paediatrics; The University of Melbourne; Melbourne Victoria Australia
| | - Gabrielle R. Wilson
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute; Melbourne Victoria Australia
- Department of Paediatrics; The University of Melbourne; Melbourne Victoria Australia
| | - Sarah E. M. Stephenson
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute; Melbourne Victoria Australia
- Department of Paediatrics; The University of Melbourne; Melbourne Victoria Australia
| | - Kiymet Bozaoglu
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute; Melbourne Victoria Australia
- Department of Paediatrics; The University of Melbourne; Melbourne Victoria Australia
| | - Matthew J. Farrer
- Djavad Mowafaghian Centre for Brain Health, Centre of Applied Neurogenetics, Department of Medical Genetics; University of British Columbia; Vancouver British Columbia Canada
| | - Paul J. Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute; Melbourne Victoria Australia
- Department of Paediatrics; The University of Melbourne; Melbourne Victoria Australia
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Abstract
This chapter reviews the diseases of the peripheral nerves from a neuropathologic point of view, with a special focus on specific morphologic changes, and includes a summary of the histopathologic methods available for their diagnosis. As the rate of obesity and the prevalence of type 2 diabetes increase, diabetic neuropathy is the most common cause of peripheral neuropathy. Many systemic disorders with metabolic origin, like amyloidosis, hepatic failure, vitamin deficiencies, uremia, lipid metabolism disorders, and others, can also cause axonal or myelin alterations in the peripheral nervous system. The most notable causes of toxic neuropathies are chemotherapeutic agents, alcohol consumption, and exposure to heavy metals and other environmental or biologic toxins. Inflammatory neuropathies cover infectious neuropathies (Lyme disease, human immunodeficiency virus, leprosy, hepatitis) and neuropathies of autoimmune origin (sarcoidosis, Guillain-Barré syndrome/acute inflammatory demyelinating polyneuropathy, chronic inflammatory demyelinating polyneuropathy, and diverse forms of vasculitis. The increasing number of known diseases causing gene mutations in hereditary peripheral neuropathies requires precise characterization, which includes histopathology.
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Weis J, Claeys KG, Roos A, Azzedine H, Katona I, Schröder JM, Senderek J. Towards a functional pathology of hereditary neuropathies. Acta Neuropathol 2017; 133:493-515. [PMID: 27896434 DOI: 10.1007/s00401-016-1645-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 11/10/2016] [Accepted: 11/13/2016] [Indexed: 12/11/2022]
Abstract
A growing number of hereditary neuropathies have been assigned to causative gene defects in recent years. The study of human nerve biopsy samples has contributed substantially to the discovery of many of these neuropathy genes. Genotype-phenotype correlations based on peripheral nerve pathology have provided a comprehensive picture of the consequences of these mutations. Intriguingly, several gene defects lead to distinguishable lesion patterns that can be studied in nerve biopsies. These characteristic features include the loss of certain nerve fiber populations and a large spectrum of distinct structural changes of axons, Schwann cells and other components of peripheral nerves. In several instances the lesion patterns are directly or indirectly linked to the known functions of the mutated gene. The present review is designed to provide an overview on these characteristic patterns. It also considers other aspects important for the manifestation and pathology of hereditary neuropathies including the role of inflammation, effects of chemotherapeutic agents and alterations detectable in skin biopsies.
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Affiliation(s)
- Joachim Weis
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074, Aachen, Germany.
| | - Kristl G Claeys
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074, Aachen, Germany
- Department of Neurology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074, Aachen, Germany
- Department of Neurology, University Hospitals Leuven and University of Leuven (KU Leuven), Leuven, Belgium
| | - Andreas Roos
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074, Aachen, Germany
- Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Otto-Hahn-Str. 6b, 44227, Dortmund, Germany
| | - Hamid Azzedine
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074, Aachen, Germany
| | - Istvan Katona
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074, Aachen, Germany
| | - J Michael Schröder
- Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstr. 30, 52074, Aachen, Germany
| | - Jan Senderek
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Ziemssenstr. 1a, 80336, Munich, Germany.
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Charcot Marie Tooth 2B Peripheral Sensory Neuropathy: How Rab7 Mutations Impact NGF Signaling? Int J Mol Sci 2017; 18:ijms18020324. [PMID: 28165391 PMCID: PMC5343860 DOI: 10.3390/ijms18020324] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/10/2017] [Accepted: 01/15/2017] [Indexed: 12/12/2022] Open
Abstract
Charcot-Marie-Tooth 2B peripheral sensory neuropathy (CMT2B) is a debilitating autosomal dominant hereditary sensory neuropathy. Patients with this disease lose pain sensation and frequently need amputation. Axonal dysfunction and degeneration of peripheral sensory neurons is a major clinical manifestation of CMT2B. However, the cellular and molecular pathogenic mechanisms remain undefined. CMT2B is caused by missense point mutations (L129F, K157N, N161T/I, V162M) in Rab7 GTPase. Strong evidence suggests that the Rab7 mutation(s) enhances the cellular levels of activated Rab7 proteins, thus resulting in increased lysosomal activity and autophagy. As a consequence, trafficking and signaling of neurotrophic factors such as nerve growth factor (NGF) in the long axons of peripheral sensory neurons are particularly vulnerable to premature degradation. A “gain of toxicity” model has, thus, been proposed based on these observations. However, studies of fly photo-sensory neurons indicate that the Rab7 mutation(s) causes a “loss of function”, resulting in haploinsufficiency. In the review, we summarize experimental evidence for both hypotheses. We argue that better models (rodent animals and human neurons) of CMT2B are needed to precisely define the disease mechanisms.
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Charcot-Marie-Tooth 2b associated Rab7 mutations cause axon growth and guidance defects during vertebrate sensory neuron development. Neural Dev 2016; 11:2. [PMID: 26791407 PMCID: PMC4721196 DOI: 10.1186/s13064-016-0058-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 01/11/2016] [Indexed: 12/02/2022] Open
Abstract
Background Charcot-Marie-Tooth2b (CMT2b) is an axonal form of a human neurodegenerative disease that preferentially affects sensory neurons. CMT2b is dominantly inherited and is characterized by unusually early onset, presenting in the second or third decade of life. Five missense mutations in the gene encoding Rab7 GTPase have been identified as causative in human CMT2b disease. Although several studies have modeled CMT2b disease in cultured neurons and in Drosophila, the mechanisms by which defective Rab7 leads to disease remain poorly understood. Results We used zebrafish to investigate the effects of CMT2b-associated Rab7 mutations in a vertebrate model. We generated transgenic animals expressing the CMT2b-associated mutant forms of Rab7 in sensory neurons, and show that these Rab7 variants cause neurodevelopmental defects, including defects in sensory axon growth, branching and pathfinding at early developmental stages. We also find reduced axon growth and branching in neurons expressing a constitutively active form of Rab7, suggesting these defects may be caused by Rab7 gain-of-function. Further, we use high-speed, high-resolution imaging of endosome transport in vivo and find that CMT2b-associated Rab7 variants cause reduced vesicle speeds, suggesting altered transport may underlie axon development defects. Conclusions Our data provide new insight into how disease-associated alterations in Rab7 protein disrupt cellular function in vertebrate sensory neurons. Moreover, our findings suggest that defects in axon development may be a previously unrecognized component of CMT2b disease.
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Strain-Specific Altered Regulatory Response of Rab7a and Tau in Creutzfeldt-Jakob Disease and Alzheimer's Disease. Mol Neurobiol 2016; 54:697-709. [PMID: 26768426 DOI: 10.1007/s12035-016-9694-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/05/2016] [Indexed: 09/29/2022]
Abstract
There is an increasing demand for the understanding of pathophysiology on neurodegeneration diseases at early stages. Changes in endocytic machinery and the cytoskeleton-associated response are the first alterations observed in Creutzfeldt-Jakob disease (CJD) and Alzheimer's disease AD brain. In this study, we performed a targeted search for endocytic pathway proteins in the different regions of the brain. We found late endosome marker Rab7a which was significantly upregulated in the frontal cortex region in the rapid progressive CJD form (MM1) and rapid progressive AD (rpAD) forms. However, Rab9 expression was significantly downregulated only in CJD-MM1 brain frontal cortex region. In the cerebellum, Rab7a expression showed significant upregulation in both subtype MM1 and VV2 CJD forms, in contrast to Rab9 which showed significant downregulation in both subtype MM1 and VV2 CJD forms at terminal stage of the disease. To check regulatory response at pre-symptomatic stage of the disease, we checked the regulatory interactive response of Rab7a, Rab9, and known biomarkers PrPC and tau forms in frontal cortex at pre-symptomatic stage of the disease in tg340 mice expressing about fourfold of human PrP-M129 with PrP-null background that had been inoculated with human sCJD MM1 brain tissue homogenates (sCJD MM1 mice). In addition, we analyzed 5XFAD mice, exhibiting five mutations in the APP and presenilin genes related to familial Alzheimer's disease (FAD), to validate specific regulatory response of Rab7a, Rab9, tau, and phosphorylated form of tau by immunostaining 5XFAD mice in comparison with the wild-type age-matched mice brain. The cortical region of 5XFAD mice brain showed accumulated form of Rab7a in puncta that co-label for p-Tau, indicating colocalization by using confocal laser-scanning microscopy and was confirmed by using reverse co-immunoprecipitation. Furthermore, synthetic RNA (siRNA) against the Rab7a gene decreased expression of Rab7a protein, in cortical primary neuronal cultures of PrPC wild type. This depleted expression of Rab7a led to the increased accumulation of PrPC in Rab9-positive endosomal compartments and consequently an increased co-localization between PrPC/Rab9; however, total tau level decreased. Interestingly, siRNA against tau gene in cortical primary neuronal cultures of PrPC wild-type mice showed enhanced Rab7a and Rab9 expression and increase formation of dendritic spines. The work described highlighted the selective involvement of late endosomal compartment marker Rab7a in CJD, slow and rapid progressive forms of AD pathogenesis.
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Tourtellotte WG. Axon Transport and Neuropathy: Relevant Perspectives on the Etiopathogenesis of Familial Dysautonomia. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 186:489-99. [PMID: 26724390 DOI: 10.1016/j.ajpath.2015.10.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 10/30/2015] [Indexed: 12/15/2022]
Abstract
Peripheral neuropathies are highly prevalent and are most often associated with chronic disease, side effects from chemotherapy, or toxic-metabolic abnormalities. Neuropathies are less commonly caused by genetic mutations, but studies of the normal function of mutated proteins have identified particular vulnerabilities that often implicate mitochondrial dynamics and axon transport mechanisms. Hereditary sensory and autonomic neuropathies are a group of phenotypically related diseases caused by monogenic mutations that primarily affect sympathetic and sensory neurons. Here, I review evidence to indicate that many genetic neuropathies are caused by abnormalities in axon transport. Moreover, in hereditary sensory and autonomic neuropathies. There may be specific convergence on gene mutations that disrupt nerve growth factor signaling, upon which sympathetic and sensory neurons critically depend.
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Affiliation(s)
- Warren G Tourtellotte
- Division of Neuropathology, Department of Pathology, and the Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
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36
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Introduzione sugli aspetti genetici delle neuropatie. Neurologia 2015. [DOI: 10.1016/s1634-7072(15)72178-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
Rab proteins represent the largest branch of the Ras-like small GTPase superfamily and there are 66 Rab genes in the human genome. They alternate between GTP- and GDP-bound states, which are facilitated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), and function as molecular switches in regulation of intracellular membrane trafficking in all eukaryotic cells. Each Rab targets to an organelle and specify a transport step along exocytic, endocytic, and recycling pathways as well as the crosstalk between these pathways. Through interactions with multiple effectors temporally, a Rab can control membrane budding and formation of transport vesicles, vesicle movement along cytoskeleton, and membrane fusion at the target compartment. The large number of Rab proteins reflects the complexity of the intracellular transport system, which is essential for the localization and function of membrane and secretory proteins such as hormones, growth factors, and their membrane receptors. As such, Rab proteins have emerged as important regulators for signal transduction, cell growth, and differentiation. Altered Rab expression and/or activity have been implicated in diseases ranging from neurological disorders, diabetes to cancer.
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Affiliation(s)
- Guangpu Li
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, 975 NE 10 Street, BRC 417, Oklahoma City, OK, 73104, USA,
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The role of rab proteins in neuronal cells and in the trafficking of neurotrophin receptors. MEMBRANES 2014; 4:642-77. [PMID: 25295627 PMCID: PMC4289860 DOI: 10.3390/membranes4040642] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/27/2014] [Accepted: 09/16/2014] [Indexed: 12/11/2022]
Abstract
Neurotrophins are a family of proteins that are important for neuronal development, neuronal survival and neuronal functions. Neurotrophins exert their role by binding to their receptors, the Trk family of receptor tyrosine kinases (TrkA, TrkB, and TrkC) and p75NTR, a member of the tumor necrosis factor (TNF) receptor superfamily. Binding of neurotrophins to receptors triggers a complex series of signal transduction events, which are able to induce neuronal differentiation but are also responsible for neuronal maintenance and neuronal functions. Rab proteins are small GTPases localized to the cytosolic surface of specific intracellular compartments and are involved in controlling vesicular transport. Rab proteins, acting as master regulators of the membrane trafficking network, play a central role in both trafficking and signaling pathways of neurotrophin receptors. Axonal transport represents the Achilles' heel of neurons, due to the long-range distance that molecules, organelles and, in particular, neurotrophin-receptor complexes have to cover. Indeed, alterations of axonal transport and, specifically, of axonal trafficking of neurotrophin receptors are responsible for several human neurodegenerative diseases, such as Huntington's disease, Alzheimer's disease, amyotrophic lateral sclerosis and some forms of Charcot-Marie-Tooth disease. In this review, we will discuss the link between Rab proteins and neurotrophin receptor trafficking and their influence on downstream signaling pathways.
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Janssens K, Goethals S, Atkinson D, Ermanoska B, Fransen E, Jordanova A, Auer-Grumbach M, Asselbergh B, Timmerman V. Human Rab7 mutation mimics features of Charcot-Marie-Tooth neuropathy type 2B in Drosophila. Neurobiol Dis 2014; 65:211-9. [PMID: 24521780 DOI: 10.1016/j.nbd.2014.01.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 12/23/2013] [Accepted: 01/30/2014] [Indexed: 12/17/2022] Open
Abstract
Charcot-Marie-Tooth disease type 2B (CMT2B) is an inherited axonal peripheral neuropathy. It is characterised by prominent sensory loss, often complicated by severe ulcero-mutilations of toes or feet, and variable motor involvement. Missense mutations in RAB7A, the gene encoding the small GTPase Rab7, cause CMT2B and increase Rab7 activity. Rab7 is ubiquitously expressed and is involved in degradation through the lysosomal pathway. In the neurons, Rab7 plays a role in the long-range retrograde transport of signalling endosomes in the axons. Here we developed the first animal model of CMT2B, modelling one of the mutations (L129F) in Drosophila melanogaster. Behavioural assays show that this model recapitulates several hallmarks of the human disease. Upon expression of mutant Rab7 in the sensory neurons, larvae present with a reduction of temperature and pain perception. Furthermore, the larvae exhibit a crawling defect when the mutant protein is expressed in the motor neurons. Analysis of axonal transport of Rab7 positive vesicles in sensory neurons of Drosophila larvae and in neurites of mammalian neuroblastoma cells demonstrates that mutant vesicles pause less than their wild-type counterparts. This latter finding indicates that alterations in vesicle transport might contribute to the pathomechanism of CMT2B.
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Affiliation(s)
- Katrien Janssens
- Molecular Genetics Department, VIB, University of Antwerp, B-2610 Antwerpen, Belgium; Department of Medical Genetics, University of Antwerp, B-2610 Antwerpen, Belgium
| | - Sofie Goethals
- Molecular Genetics Department, VIB, University of Antwerp, B-2610 Antwerpen, Belgium; Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, B-2610 Antwerpen, Belgium
| | - Derek Atkinson
- Molecular Genetics Department, VIB, University of Antwerp, B-2610 Antwerpen, Belgium; Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, B-2610 Antwerpen, Belgium
| | - Biljana Ermanoska
- Molecular Genetics Department, VIB, University of Antwerp, B-2610 Antwerpen, Belgium; Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, B-2610 Antwerpen, Belgium
| | - Erik Fransen
- StatUa Center for Statistics, University of Antwerp, B-2000 Antwerpen, Belgium
| | - Albena Jordanova
- Molecular Genetics Department, VIB, University of Antwerp, B-2610 Antwerpen, Belgium; Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, B-2610 Antwerpen, Belgium
| | | | - Bob Asselbergh
- Molecular Genetics Department, VIB, University of Antwerp, B-2610 Antwerpen, Belgium; Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, B-2610 Antwerpen, Belgium
| | - Vincent Timmerman
- Molecular Genetics Department, VIB, University of Antwerp, B-2610 Antwerpen, Belgium; Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, B-2610 Antwerpen, Belgium.
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D'Adamo P, Masetti M, Bianchi V, Morè L, Mignogna ML, Giannandrea M, Gatti S. RAB GTPases and RAB-interacting proteins and their role in the control of cognitive functions. Neurosci Biobehav Rev 2014; 46 Pt 2:302-14. [PMID: 24412241 DOI: 10.1016/j.neubiorev.2013.12.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 11/15/2013] [Accepted: 12/16/2013] [Indexed: 12/18/2022]
Abstract
A RAS-related class of small monomeric G proteins, the RAB GTPases, is emerging as of key biological importance in compartment specific directional control of vesicles formation, transport and fusion. Thanks to human genetic observation and to the consequent dedicated biochemical work, substantial progress has been made on the understanding of the role played by RAB GTPases and their effector proteins on neuronal development and the shaping of cognitive functions. This review is highlighting these initial elements to broaden the current scope of research on developmental cognitive deficits and take the point of view of RAB GTPases control on membrane transport in neurons and astrocytes.
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Affiliation(s)
- Patrizia D'Adamo
- Dulbecco Telethon Institute at San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milan, Italy; Vita-Salute San Raffaele University, via Olgettina 58, 20132 Milan, Italy.
| | - Michela Masetti
- Dulbecco Telethon Institute at San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milan, Italy
| | - Veronica Bianchi
- Dulbecco Telethon Institute at San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milan, Italy; Vita-Salute San Raffaele University, via Olgettina 58, 20132 Milan, Italy
| | - Lorenzo Morè
- Dulbecco Telethon Institute at San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milan, Italy
| | - Maria Lidia Mignogna
- Dulbecco Telethon Institute at San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milan, Italy; Vita-Salute San Raffaele University, via Olgettina 58, 20132 Milan, Italy
| | - Maila Giannandrea
- Dulbecco Telethon Institute at San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milan, Italy; F. Hoffmann-La Roche AG, pRED Pharma Research & Early Development, DTA Neuroscience Grenzacherstrasse 124, Basel CH4070, Switzerland
| | - Silvia Gatti
- F. Hoffmann-La Roche AG, pRED Pharma Research & Early Development, DTA Neuroscience Grenzacherstrasse 124, Basel CH4070, Switzerland
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Cherry S, Jin EJ, Ozel MN, Lu Z, Agi E, Wang D, Jung WH, Epstein D, Meinertzhagen IA, Chan CC, Hiesinger PR. Charcot-Marie-Tooth 2B mutations in rab7 cause dosage-dependent neurodegeneration due to partial loss of function. eLife 2013; 2:e01064. [PMID: 24327558 PMCID: PMC3857549 DOI: 10.7554/elife.01064] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The small GTPase Rab7 is a key regulator of endosomal maturation in eukaryotic cells. Mutations in rab7 are thought to cause the dominant neuropathy Charcot-Marie-Tooth 2B (CMT2B) by a gain-of-function mechanism. Here we show that loss of rab7, but not overexpression of rab7 CMT2B mutants, causes adult-onset neurodegeneration in a Drosophila model. All CMT2B mutant proteins retain 10–50% function based on quantitative imaging, electrophysiology, and rescue experiments in sensory and motor neurons in vivo. Consequently, expression of CMT2B mutants at levels between 0.5 and 10-fold their endogenous levels fully rescues the neuropathy-like phenotypes of the rab7 mutant. Live imaging reveals that CMT2B proteins are inefficiently recruited to endosomes, but do not impair endosomal maturation. These findings are not consistent with a gain-of-function mechanism. Instead, they indicate a dosage-dependent sensitivity of neurons to rab7-dependent degradation. Our results suggest a therapeutic approach opposite to the currently proposed reduction of mutant protein function. DOI:http://dx.doi.org/10.7554/eLife.01064.001 Charcot-Marie-Tooth disease is an inherited disorder of the nervous system with symptoms that typically begin in adolescence or early adulthood. The sensory and motor nerves gradually degenerate, causing muscles to waste away and leading to the loss of touch sensation across the body. One subtype of the disease—Charcot-Marie-Tooth 2B—is caused by mutations in a gene called rab7, which codes for a protein that helps to regulate the breakdown of waste proteins inside cells. Charcot-Marie-Tooth 2B is described as a genetically dominant disorder because all patients have one wild type copy and one mutant copy of the rab7 gene. Overexpression of the mutant gene in cells grown in culture alters many of the signaling pathways inside the cells, but it is unclear whether these alterations cause the pathology seen in the disease. Now, Cherry et al. have obtained new insights into the genetics of Charcot-Marie-Tooth 2B by creating the first animal model of the disorder. Fruit flies that did not have the rab7 gene in the light-sensitive sensory neurons in their eyes were used to compare normal and mutant cells. While the two cell types were initially similar, the mutant cells gradually degenerated in the adult animal. By contrast, cells that overexpressed a mutant form of the rab7 gene continued to function normally throughout adulthood. Moreover, when mutant Rab7 proteins were introduced into the cells that lacked the rab7 gene, the proteins restored the cells’ sensitivity to light. These results suggest that mutant Rab7 proteins do not cause degeneration; instead, it is the loss of normal Rab7 function that causes problems. At present, most research into treatment is aimed at finding ways to reduce the activity of mutant Rab7 proteins. However, the work of Cherry et al. suggests that increasing the activity of normal Rab7 proteins—or increasing the activity of alternative pathways that degrade waste proteins—may help to restore nerve function in this, and possibly other, neurodegenerative diseases. DOI:http://dx.doi.org/10.7554/eLife.01064.002
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Affiliation(s)
- Smita Cherry
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
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The synaptic maintenance problem: membrane recycling, Ca2+ homeostasis and late onset degeneration. Mol Neurodegener 2013; 8:23. [PMID: 23829673 PMCID: PMC3708831 DOI: 10.1186/1750-1326-8-23] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/05/2013] [Indexed: 01/02/2023] Open
Abstract
Most neurons are born with the potential to live for the entire lifespan of the organism. In addition, neurons are highly polarized cells with often long axons, extensively branched dendritic trees and many synaptic contacts. Longevity together with morphological complexity results in a formidable challenge to maintain synapses healthy and functional. This challenge is often evoked to explain adult-onset degeneration in numerous neurodegenerative disorders that result from otherwise divergent causes. However, comparably little is known about the basic cell biological mechanisms that keep normal synapses alive and functional in the first place. How the basic maintenance mechanisms are related to slow adult-onset degeneration in different diseasesis largely unclear. In this review we focus on two basic and interconnected cell biological mechanisms that are required for synaptic maintenance: endomembrane recycling and calcium (Ca2+) homeostasis. We propose that subtle defects in these homeostatic processes can lead to late onset synaptic degeneration. Moreover, the same basic mechanisms are hijacked, impaired or overstimulated in numerous neurodegenerative disorders. Understanding the pathogenesis of these disorders requires an understanding of both the initial cause of the disease and the on-going changes in basic maintenance mechanisms. Here we discuss the mechanisms that keep synapses functional over long periods of time with the emphasis on their role in slow adult-onset neurodegeneration.
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Abstract
Retrograde trophic signaling of nerve growth factor (NGF) supports neuronal survival and differentiation. Dysregulated trophic signaling could lead to various neurological disorders. Charcot-Marie-Tooth type 2B (CMT2B) is one of the most common inherited peripheral neuropathies characterized by severe terminal axonal loss. Genetic analysis of human CMT2B patients has revealed four missense point mutations in Rab7, a small GTPase that regulates late endosomal/lysosomal pathways, but the exact pathological mechanism remains poorly understood. Here, we show that these Rab7 mutants dysregulated axonal transport and diminished the retrograde signaling of NGF and its TrkA receptor. We found that all CMT2B Rab7 mutants were transported significantly faster than Rab7(wt) in the anterograde direction, accompanied with an increased percentile of anterograde Rab7-vesicles within axons of rat E15.5 dorsal root ganglion (DRG) neurons. In PC12M cells, the CMT2B Rab7 mutants drastically reduced the level of surface TrkA and NGF binding, presumably by premature degradation of TrkA. On the other hand, siRNA knock-down of endogenous Rab7 led to the appearance of large TrkA puncta in enlarged Rab5-early endosomes within the cytoplasm, suggesting delayed TrkA degradation. We also show that CMT2B Rab7 mutants markedly impaired NGF-induced Erk1/2 activation and differentiation in PC12M cells. Further analysis revealed that CMT2B Rab7 mutants caused axonal degeneration in rat E15.5 DRG neurons. We propose that Rab7 mutants induce premature degradation of retrograde NGF-TrkA trophic signaling, which may potentially contribute to the CMT2B disease.
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Seixas E, Barros M, Seabra MC, Barral DC. Rab and Arf proteins in genetic diseases. Traffic 2013; 14:871-85. [PMID: 23565987 DOI: 10.1111/tra.12072] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 04/03/2013] [Accepted: 04/08/2013] [Indexed: 01/29/2023]
Abstract
Rab and ADP-ribosylation factor (Arf) family proteins are master regulators of membrane trafficking and are involved in all steps of vesicular transport. These families of small guanine-nucleotide-binding (G) proteins are well suited to regulate membrane trafficking processes since their nucleotide state determines their conformation and the capacity to bind to a multitude of effectors, which mediate their functions. In recent years, several inherited diseases have been associated with mutations in genes encoding proteins belonging to these two families or in proteins that regulate their GTP-binding cycle. The genetic diseases that are caused by defects in Rabs, Arfs or their regulatory proteins are heterogeneous and display diverse symptoms. However, these diseases mainly affect two types of subcellular compartments, namely lysosome-related organelles and cilia. Also, several of these diseases affect the nervous system. Thus, the study of these diseases represents an opportunity to understand their etiology and the molecular mechanisms involved, as well as to develop novel therapeutic strategies.
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Affiliation(s)
- Elsa Seixas
- CEDOC, Faculdade de Ciências Médicas, FCM, Universidade Nova de Lisboa, 1169-056, Lisboa, Portugal
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Cogli L, Progida C, Bramato R, Bucci C. Vimentin phosphorylation and assembly are regulated by the small GTPase Rab7a. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1283-93. [PMID: 23458836 PMCID: PMC3787733 DOI: 10.1016/j.bbamcr.2013.02.024] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 11/30/2022]
Abstract
Intermediate filaments are cytoskeletal elements important for cell architecture. Recently it has been discovered that intermediate filaments are highly dynamic and that they are fundamental for organelle positioning, transport and function thus being an important regulatory component of membrane traffic. We have identified, using the yeast two-hybrid system, vimentin, a class III intermediate filament protein, as a Rab7a interacting protein. Rab7a is a member of the Rab family of small GTPases and it controls vesicular membrane traffic to late endosomes and lysosomes. In addition, Rab7a is important for maturation of phagosomes and autophagic vacuoles. We confirmed the interaction in HeLa cells by co-immunoprecipitation and pull-down experiments, and established that the interaction is direct using bacterially expressed recombinant proteins. Immunofluorescence analysis on HeLa cells indicate that Rab7a-positive vesicles sometimes overlap with vimentin filaments. Overexpression of Rab7a causes an increase in vimentin phosphorylation at different sites and causes redistribution of vimentin in the soluble fraction. Consistently, Rab7a silencing causes an increase of vimentin present in the insoluble fraction (assembled). Also, expression of Charcot–Marie–Tooth 2B-causing Rab7a mutant proteins induces vimentin phosphorylation and increases the amount of vimentin in the soluble fraction. Thus, modulation of expression levels of Rab7a wt or expression of Rab7a mutant proteins changes the assembly of vimentin and its phosphorylation state indicating that Rab7a is important for the regulation of vimentin function. ► We searched for new Rab7a interacting proteins and we found vimentin. ► We demonstrated that Rab7a interacts directly with vimentin. ► Rab7a influences vimentin's phosphorylation and soluble/insoluble ratio. ► Rab7a regulates vimentin organization and function.
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Affiliation(s)
- Laura Cogli
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
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Cogli L, Progida C, Thomas CL, Spencer-Dene B, Donno C, Schiavo G, Bucci C. Charcot-Marie-Tooth type 2B disease-causing RAB7A mutant proteins show altered interaction with the neuronal intermediate filament peripherin. Acta Neuropathol 2013; 125:257-72. [PMID: 23179371 PMCID: PMC3549248 DOI: 10.1007/s00401-012-1063-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 10/29/2012] [Accepted: 10/29/2012] [Indexed: 12/13/2022]
Abstract
Charcot-Marie-Tooth type 2B (CMT2B) is a peripheral ulcero-mutilating neuropathy caused by four missense mutations in the rab7a gene. CMT2B is clinically characterized by prominent sensory loss, distal muscle weakness leading to muscle atrophy, high frequency of foot ulcers and infections that often results in toe amputations. RAB7A is a ubiquitous small GTPase, which controls transport to late endocytic compartments. Although the biochemical and functional properties of disease-causing RAB7A mutant proteins have been investigated, it is not yet clear how the disease originates. To understand how mutations in a ubiquitous protein specifically affect peripheral neurons, we performed a two-hybrid screen using a dorsal root ganglia cDNA library with the purpose of identifying RAB7A interactors specific for these cells. We identified peripherin, an intermediate filament protein expressed primarily in peripheral neurons, as a putative RAB7A interacting protein. The interaction was confirmed by co-immunoprecipitation and pull-down experiments, and established that the interaction is direct using recombinant proteins. Silencing or overexpression of wild type RAB7A changed the soluble/insoluble rate of peripherin indicating that RAB7A is important for peripherin organization and function. In addition, disease-causing RAB7A mutant proteins bind more strongly to peripherin and their expression causes a significant increase in the amount of soluble peripherin. Since peripherin plays a role not only in neurite outgrowth during development but also in axonal regeneration after injury, these data suggest that the altered interaction between disease-causing RAB7A mutants and peripherin could play an important role in CMT2B neuropathy.
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Affiliation(s)
- Laura Cogli
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via Provinciale Monteroni 165, 73100 Lecce, Italy
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Abstract
Hereditary sensory and autonomic neuropathies (HSN/HSAN) are clinically and genetically heterogeneous disorders of the peripheral nervous system that predominantly affect the sensory and autonomic neurons. Hallmark features comprise not only prominent sensory signs and symptoms and ulcerative mutilations but also variable autonomic and motor disturbances. Autosomal dominant and autosomal recessive inheritance has been reported. Molecular genetics studies have identified disease-causing mutations in 11 genes. Some of the affected proteins have nerve-specific roles but underlying mechanisms have also been shown to involve sphingolipid metabolism, vesicular transport, structural integrity, and transcription regulation. Genetic and functional studies have substantially improved the understanding of the pathogenesis of the HSN/HSAN and will help to find preventive and causative therapies in the future.
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Pareyson D, Marchesi C, Salsano E. Dominant Charcot-Marie-Tooth syndrome and cognate disorders. HANDBOOK OF CLINICAL NEUROLOGY 2013; 115:817-845. [PMID: 23931817 DOI: 10.1016/b978-0-444-52902-2.00047-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Charcot-Marie-Tooth neuropathy (CMT) is a group of genetically heterogeneous disorders sharing a similar phenotype, characterized by wasting and weakness mainly involving the distal muscles of lower and upper limbs, variably associated with distal sensory loss and skeletal deformities. This chapter deals with dominantly transmitted CMT and related disorders, namely hereditary neuropathy with liability to pressure palsies (HNPP) and hereditary neuralgic amyotrophy (HNA). During the last 20 years, several genes have been uncovered associated with CMT and our understanding of the underlying molecular mechanisms has greatly improved. Consequently, a precise genetic diagnosis is now possible in the majority of cases, thus allowing proper genetic counseling. Although, unfortunately, treatment is still unavailable for all types of CMT, several cellular and animal models have been developed and some compounds have proved effective in these models. The first trials with ascorbic acid in CMT type 1A have been completed and, although negative, are providing relevant information on disease course and on how to prepare for future trials.
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Affiliation(s)
- Davide Pareyson
- Clinics of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences, IRCCS Foundation, C. Besta Neurological Institute, Milan, Italy.
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Abstract
The inherited neuropathies are a clinically and genetically heterogeneous group of disorders in which there have been rapid advances in the last two decades. Molecular genetic testing is now an integral part of the evaluation of patients with inherited neuropathies. In this chapter we describe the genes responsible for the primary inherited neuropathies. We briefly discuss the clinical phenotype of each of the known inherited neuropathy subgroups, describe algorithms for molecular genetic testing of affected patients and discuss genetic counseling. The basic principles of careful phenotyping, documenting an accurate family history, and testing the available genes in an appropriate manner should identify the vast majority of individuals with CMT1 and many of those with CMT2. In this chapter we also describe the current methods of genetic testing. As advances are made in molecular genetic technologies and improvements are made in bioinformatics, it is likely that the current time-consuming methods of DNA sequencing will give way to quicker and more efficient high-throughput methods, which are briefly discussed here.
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