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Tabatabaii SA, Kianparsa J, Zavareh MHG, Khosravi A, Bahadori AR, Farahbakhsh N. Noninvasive ventilation and laser-assisted unilateral posterior cordotomy as novel multidisciplinary approaches for Charcot-Marie-Tooth disease 4B vocal cord paralysis: a case report. J Med Case Rep 2024; 18:401. [PMID: 39217382 PMCID: PMC11366128 DOI: 10.1186/s13256-024-04742-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Accepted: 08/08/2024] [Indexed: 09/04/2024] Open
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) is one of the most common inherited neuropathies. The disease is generally characterized by sensory loss most prominent in distal extremities, muscle weakness, and muscle wasting. There is still no effective therapy for Charcot-Marie-Tooth disease. CASE PRESENTATION The patient is a 6-year-old Iranian girl, of Fars ethnicity, who was admitted with a chief complaint of hoarseness and an impression of Charcot-Marie-Tooth disease type 4B. She was initially treated with noninvasive ventilation and, after a year, electively underwent cordotomy as a novel therapeutic approach. CONCLUSIONS Charcot-Marie-Tooth disease type 4B is a less common but important cause of stridor. Noninvasive ventilation treatment and unilateral posterior cordotomy can be utilized for hereditary neuropathies.
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Affiliation(s)
- Seyed Ahmad Tabatabaii
- Department of Pediatric Pulmonology, Mofid Pediatrics Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Joben Kianparsa
- Student Research Committee, Faculty of Medicine, Shahed University, Tehran, Iran
| | | | - Abolfazl Khosravi
- Student Research Committee, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Nazanin Farahbakhsh
- Department of Pediatric Pulmonology, Mofid Pediatrics Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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2
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Scherer SS, Svaren J. Peripheral Nervous System (PNS) Myelin Diseases. Cold Spring Harb Perspect Biol 2024; 16:a041376. [PMID: 38253417 PMCID: PMC11065170 DOI: 10.1101/cshperspect.a041376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
This is a review of inherited and acquired causes of human demyelinating neuropathies and a subset of disorders that affect axon-Schwann cell interactions. Nearly all inherited demyelinating neuropathies are caused by mutations in genes that are expressed by myelinating Schwann cells, affecting diverse functions in a cell-autonomous manner. The most common acquired demyelinating neuropathies are Guillain-Barré syndrome and chronic, inflammatory demyelinating polyneuropathy, both of which are immune-mediated. An additional group of inherited and acquired disorders affect axon-Schwann cell interactions in the nodal region. Overall, these disorders affect the formation of myelin and its maintenance, with superimposed axonal loss that is clinically important.
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Affiliation(s)
- Steven S Scherer
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - John Svaren
- Department of Comparative Biosciences, Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
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3
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Stefani C, Bruchez AM, Rosasco MG, Yoshida AE, Fasano KJ, Levan PF, Lorant A, Hubbard NW, Oberst A, Stuart LM, Lacy-Hulbert A. LITAF protects against pore-forming protein-induced cell death by promoting membrane repair. Sci Immunol 2024; 9:eabq6541. [PMID: 38181093 DOI: 10.1126/sciimmunol.abq6541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 11/09/2023] [Indexed: 01/07/2024]
Abstract
Pore-forming toxins (PFTs) are the largest class of bacterial toxins and contribute to virulence by triggering host cell death. Vertebrates also express endogenous pore-forming proteins that induce cell death as part of host defense. To mitigate damage and promote survival, cells mobilize membrane repair mechanisms to neutralize and counteract pores, but how these pathways are activated is poorly understood. Here, we use a transposon-based gene activation screen to discover pathways that counteract the cytotoxicity of the archetypal PFT Staphylococcus aureus α-toxin. We identify the endolysosomal protein LITAF as a mediator of cellular resistance to PFT-induced cell death that is active against both bacterial toxins and the endogenous pore, gasdermin D, a terminal effector of pyroptosis. Activation of the ubiquitin ligase NEDD4 by potassium efflux mobilizes LITAF to recruit the endosomal sorting complexes required for transport (ESCRT) machinery to repair damaged membrane. Cells lacking LITAF, or carrying naturally occurring disease-associated mutations of LITAF, are highly susceptible to pore-induced death. Notably, LITAF-mediated repair occurs at endosomal membranes, resulting in expulsion of damaged membranes as exosomes, rather than through direct excision of pores from the surface plasma membrane. These results identify LITAF as a key effector that links sensing of cellular damage to repair.
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Affiliation(s)
- Caroline Stefani
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Anna M Bruchez
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Mario G Rosasco
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Anna E Yoshida
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Kayla J Fasano
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Paula F Levan
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
| | - Alina Lorant
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
- Department of Immunology, University of Washington, Seattle, WA, USA
| | | | - Andrew Oberst
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Lynda M Stuart
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
- Institute for Protein Design, Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Adam Lacy-Hulbert
- Center for Systems Immunology, Benaroya Research Institute at Virginia Mason, Seattle, WA, USA
- Department of Immunology, University of Washington, Seattle, WA, USA
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4
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Derkaczew M, Martyniuk P, Hofman R, Rutkowski K, Osowski A, Wojtkiewicz J. The Genetic Background of Abnormalities in Metabolic Pathways of Phosphoinositides and Their Linkage with the Myotubular Myopathies, Neurodegenerative Disorders, and Carcinogenesis. Biomolecules 2023; 13:1550. [PMID: 37892232 PMCID: PMC10605126 DOI: 10.3390/biom13101550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 09/16/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
Myo-inositol belongs to one of the sugar alcohol groups known as cyclitols. Phosphatidylinositols are one of the derivatives of Myo-inositol, and constitute important mediators in many intracellular processes such as cell growth, cell differentiation, receptor recycling, cytoskeletal organization, and membrane fusion. They also have even more functions that are essential for cell survival. Mutations in genes encoding phosphatidylinositols and their derivatives can lead to many disorders. This review aims to perform an in-depth analysis of these connections. Many authors emphasize the significant influence of phosphatidylinositols and phosphatidylinositols' phosphates in the pathogenesis of myotubular myopathies, neurodegenerative disorders, carcinogenesis, and other less frequently observed diseases. In our review, we have focused on three of the most often mentioned groups of disorders. Inositols are the topic of many studies, and yet, there are no clear results of successful clinical trials. Analysis of the available literature gives promising results and shows that further research is still needed.
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Affiliation(s)
- Maria Derkaczew
- Department of Human Physiology and Pathophysiology, School of Medicine, Collegium Medicum, University of Warmia and Mazury, 10-082 Olsztyn, Poland
- Students’ Scientific Club of Pathophysiologists, Department of Human Physiology and Pathophysiology, School of Medicine, University of Warmia and Mazury, 10-082 Olsztyn, Poland
| | - Piotr Martyniuk
- Department of Human Physiology and Pathophysiology, School of Medicine, Collegium Medicum, University of Warmia and Mazury, 10-082 Olsztyn, Poland
- Students’ Scientific Club of Pathophysiologists, Department of Human Physiology and Pathophysiology, School of Medicine, University of Warmia and Mazury, 10-082 Olsztyn, Poland
| | - Robert Hofman
- Department of Human Physiology and Pathophysiology, School of Medicine, Collegium Medicum, University of Warmia and Mazury, 10-082 Olsztyn, Poland
- Students’ Scientific Club of Pathophysiologists, Department of Human Physiology and Pathophysiology, School of Medicine, University of Warmia and Mazury, 10-082 Olsztyn, Poland
| | - Krzysztof Rutkowski
- Students’ Scientific Club of Pathophysiologists, Department of Human Physiology and Pathophysiology, School of Medicine, University of Warmia and Mazury, 10-082 Olsztyn, Poland
- The Nicolaus Copernicus Municipal Polyclinical Hospital in Olsztyn, 10-045 Olsztyn, Poland
| | - Adam Osowski
- Department of Human Physiology and Pathophysiology, School of Medicine, Collegium Medicum, University of Warmia and Mazury, 10-082 Olsztyn, Poland
| | - Joanna Wojtkiewicz
- Department of Human Physiology and Pathophysiology, School of Medicine, Collegium Medicum, University of Warmia and Mazury, 10-082 Olsztyn, Poland
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5
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El-Bazzal L, Ghata A, Estève C, Gadacha J, Quintana P, Castro C, Roeckel-Trévisiol N, Lembo F, Lenfant N, Mégarbané A, Borg JP, Lévy N, Bartoli M, Poitelon Y, Roubertoux PL, Delague V, Bernard-Marissal N. Imbalance of NRG1-ERBB2/3 signalling underlies altered myelination in Charcot-Marie-Tooth disease 4H. Brain 2023; 146:1844-1858. [PMID: 36314052 PMCID: PMC10151191 DOI: 10.1093/brain/awac402] [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: 03/25/2022] [Revised: 08/30/2022] [Accepted: 10/02/2022] [Indexed: 11/12/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is one of the most common inherited neurological disorders, affecting either axons from the motor and/or sensory neurons or Schwann cells of the peripheral nervous system (PNS) and caused by more than 100 genes. We previously identified mutations in FGD4 as responsible for CMT4H, an autosomal recessive demyelinating form of CMT disease. FGD4 encodes FRABIN, a GDP/GTP nucleotide exchange factor, particularly for the small GTPase Cdc42. Remarkably, nerves from patients with CMT4H display excessive redundant myelin figures called outfoldings that arise from focal hypermyelination, suggesting that FRABIN could play a role in the control of PNS myelination. To gain insights into the role of FGD4/FRABIN in Schwann cell myelination, we generated a knockout mouse model (Fgd4SC-/-), with conditional ablation of Fgd4 in Schwann cells. We show that the specific deletion of FRABIN in Schwann cells leads to aberrant myelination in vitro, in dorsal root ganglia neuron/Schwann cell co-cultures, as well as in vivo, in distal sciatic nerves from Fgd4SC-/- mice. We observed that those myelination defects are related to an upregulation of some interactors of the NRG1 type III/ERBB2/3 signalling pathway, which is known to ensure a proper level of myelination in the PNS. Based on a yeast two-hybrid screen, we identified SNX3 as a new partner of FRABIN, which is involved in the regulation of endocytic trafficking. Interestingly, we showed that the loss of FRABIN impairs endocytic trafficking, which may contribute to the defective NRG1 type III/ERBB2/3 signalling and myelination. Using RNA-Seq, in vitro, we identified new potential effectors of the deregulated pathways, such as ERBIN, RAB11FIP2 and MAF, thereby providing cues to understand how FRABIN contributes to proper ERBB2 trafficking or even myelin membrane addition through cholesterol synthesis. Finally, we showed that the re-establishment of proper levels of the NRG1 type III/ERBB2/3 pathway using niacin treatment reduces myelin outfoldings in nerves of CMT4H mice. Overall, our work reveals a new role of FRABIN in the regulation of NRG1 type III/ERBB2/3 NRG1signalling and myelination and opens future therapeutic strategies based on the modulation of the NRG1 type III/ERBB2/3 pathway to reduce CMT4H pathology and more generally other demyelinating types of CMT disease.
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Affiliation(s)
- Lara El-Bazzal
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | - Adeline Ghata
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | | | - Jihane Gadacha
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | | | | | | | - Frédérique Lembo
- Aix Marseille Univ, INSERM, CNRS, CRCM, Institut Paoli-Calmettes, Marseille, France
| | | | - André Mégarbané
- Department of Human Genetics, Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Beirut, Lebanon
| | - Jean-Paul Borg
- Aix Marseille Univ, INSERM, CNRS, CRCM, Institut Paoli-Calmettes, Marseille, France
| | - Nicolas Lévy
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | - Marc Bartoli
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | - Yannick Poitelon
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA
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6
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Hu L, Brichalli W, Li N, Chen S, Cheng Y, Liu Q, Xiong Y, Yu J. Myotubularin functions through actomyosin to interact with the Hippo pathway. EMBO Rep 2022; 23:e55851. [PMID: 36285521 PMCID: PMC9724681 DOI: 10.15252/embr.202255851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 10/01/2022] [Accepted: 10/07/2022] [Indexed: 12/12/2022] Open
Abstract
The Hippo pathway is an evolutionarily conserved developmental pathway that controls organ size by integrating diverse regulatory inputs, including actomyosin-mediated cytoskeletal tension. Despite established connections between the actomyosin cytoskeleton and the Hippo pathway, the upstream regulation of actomyosin in the Hippo pathway is less defined. Here, we identify the phosphoinositide-3-phosphatase Myotubularin (Mtm) as a novel upstream regulator of actomyosin that functions synergistically with the Hippo pathway during growth control. Mechanistically, Mtm regulates membrane phospholipid PI(3)P dynamics, which, in turn, modulates actomyosin activity through Rab11-mediated vesicular trafficking. We reveal PI(3)P dynamics as a novel mode of upstream regulation of actomyosin and establish Rab11-mediated vesicular trafficking as a functional link between membrane lipid dynamics and actomyosin activation in the context of growth control. Our study also shows that MTMR2, the human counterpart of Drosophila Mtm, has conserved functions in regulating actomyosin activity and tissue growth, providing new insights into the molecular basis of MTMR2-related peripheral nerve myelination and human disorders.
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Affiliation(s)
- Liang Hu
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
| | - Wyatt Brichalli
- Department of Anatomy & PhysiologyKansas State University College of Veterinary MedicineManhattanKSUSA
| | - Naren Li
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
| | - Shifan Chen
- Department of NeuroscienceUniversity of Connecticut School of MedicineFarmingtonCTUSA
| | - Yaqing Cheng
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
| | - Qinfang Liu
- Department of NeuroscienceUniversity of Connecticut School of MedicineFarmingtonCTUSA
| | - Yulan Xiong
- Department of NeuroscienceUniversity of Connecticut School of MedicineFarmingtonCTUSA
| | - Jianzhong Yu
- Department of Physiology and NeurobiologyUniversity of ConnecticutStorrsCTUSA
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Abstract
Phosphoinositides are signalling lipids derived from phosphatidylinositol, a ubiquitous phospholipid in the cytoplasmic leaflet of eukaryotic membranes. Initially discovered for their roles in cell signalling, phosphoinositides are now widely recognized as key integrators of membrane dynamics that broadly impact on all aspects of cell physiology and on disease. The past decade has witnessed a vast expansion of our knowledge of phosphoinositide biology. On the endocytic and exocytic routes, phosphoinositides direct the inward and outward flow of membrane as vesicular traffic is coupled to the conversion of phosphoinositides. Moreover, recent findings on the roles of phosphoinositides in autophagy and the endolysosomal system challenge our view of lysosome biology. The non-vesicular exchange of lipids, ions and metabolites at membrane contact sites in between organelles has also been found to depend on phosphoinositides. Here we review our current understanding of how phosphoinositides shape and direct membrane dynamics to impact on cell physiology, and provide an overview of emerging concepts in phosphoinositide regulation.
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8
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Pseudophosphatases as Regulators of MAPK Signaling. Int J Mol Sci 2021; 22:ijms222212595. [PMID: 34830476 PMCID: PMC8622459 DOI: 10.3390/ijms222212595] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 01/03/2023] Open
Abstract
Mitogen-activated protein kinase (MAPK) signaling pathways are highly conserved regulators of eukaryotic cell function. These enzymes regulate many biological processes, including the cell cycle, apoptosis, differentiation, protein biosynthesis, and oncogenesis; therefore, tight control of the activity of MAPK is critical. Kinases and phosphatases are well established as MAPK activators and inhibitors, respectively. Kinases phosphorylate MAPKs, initiating and controlling the amplitude of the activation. In contrast, MAPK phosphatases (MKPs) dephosphorylate MAPKs, downregulating and controlling the duration of the signal. In addition, within the past decade, pseudoenzymes of these two families, pseudokinases and pseudophosphatases, have emerged as bona fide signaling regulators. This review discusses the role of pseudophosphatases in MAPK signaling, highlighting the function of phosphoserine/threonine/tyrosine-interacting protein (STYX) and TAK1-binding protein (TAB 1) in regulating MAPKs. Finally, a new paradigm is considered for this well-studied cellular pathway, and signal transduction pathways in general.
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Previtali SC. Peripheral Nerve Development and the Pathogenesis of Peripheral Neuropathy: the Sorting Point. Neurotherapeutics 2021; 18:2156-2168. [PMID: 34244926 PMCID: PMC8804061 DOI: 10.1007/s13311-021-01080-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2021] [Indexed: 12/12/2022] Open
Abstract
Nerve development requires a coordinated sequence of events and steps to be accomplished for the generation of functional peripheral nerves to convey sensory and motor signals. Any abnormality during development may result in pathological structure and function of the nerve, which evolves in peripheral neuropathy. In this review, we will briefly describe different steps of nerve development while we will mostly focus on the molecular mechanisms involved in radial sorting of axons, one of these nerve developmental steps. We will summarize current knowledge of molecular pathways so far reported in radial sorting and their possible interactions. Finally, we will describe how disruption of these pathways may result in human neuropathies.
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Affiliation(s)
- Stefano C Previtali
- Neuromuscular Repair Unit, InSpe (Institute of Experimental Neurology) and Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy.
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10
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Bosco L, Falzone YM, Previtali SC. Animal Models as a Tool to Design Therapeutical Strategies for CMT-like Hereditary Neuropathies. Brain Sci 2021; 11:1237. [PMID: 34573256 PMCID: PMC8465478 DOI: 10.3390/brainsci11091237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 09/05/2021] [Accepted: 09/07/2021] [Indexed: 02/07/2023] Open
Abstract
Since ancient times, animal models have provided fundamental information in medical knowledge. This also applies for discoveries in the field of inherited peripheral neuropathies (IPNs), where they have been instrumental for our understanding of nerve development, pathogenesis of neuropathy, molecules and pathways involved and to design potential therapies. In this review, we briefly describe how animal models have been used in ancient medicine until the use of rodents as the prevalent model in present times. We then travel along different examples of how rodents have been used to improve our understanding of IPNs. We do not intend to describe all discoveries and animal models developed for IPNs, but just to touch on a few arbitrary and paradigmatic examples, taken from our direct experience or from literature. The idea is to show how strategies have been developed to finally arrive to possible treatments for IPNs.
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Affiliation(s)
| | | | - Stefano Carlo Previtali
- Institute of Experimental Neurology (INSPE), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy; (L.B.); (Y.M.F.)
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Dysregulation of myelin synthesis and actomyosin function underlies aberrant myelin in CMT4B1 neuropathy. Proc Natl Acad Sci U S A 2021; 118:2009469118. [PMID: 33653949 DOI: 10.1073/pnas.2009469118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Charcot-Marie-Tooth type 4B1 (CMT4B1) is a severe autosomal recessive demyelinating neuropathy with childhood onset, caused by loss-of-function mutations in the myotubularin-related 2 (MTMR2) gene. MTMR2 is a ubiquitously expressed catalytically active 3-phosphatase, which in vitro dephosphorylates the 3-phosphoinositides PtdIns3P and PtdIns(3,5)P 2, with a preference for PtdIns(3,5)P 2 A hallmark of CMT4B1 neuropathy are redundant loops of myelin in the nerve termed myelin outfoldings, which can be considered the consequence of altered growth of myelinated fibers during postnatal development. How MTMR2 loss and the resulting imbalance of 3'-phosphoinositides cause CMT4B1 is unknown. Here we show that MTMR2 by regulating PtdIns(3,5)P 2 levels coordinates mTORC1-dependent myelin synthesis and RhoA/myosin II-dependent cytoskeletal dynamics to promote myelin membrane expansion and longitudinal myelin growth. Consistent with this, pharmacological inhibition of PtdIns(3,5)P 2 synthesis or mTORC1/RhoA signaling ameliorates CMT4B1 phenotypes. Our data reveal a crucial role for MTMR2-regulated lipid turnover to titrate mTORC1 and RhoA signaling thereby controlling myelin growth.
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12
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Mattei AM, Smailys JD, Hepworth EMW, Hinton SD. The Roles of Pseudophosphatases in Disease. Int J Mol Sci 2021; 22:ijms22136924. [PMID: 34203203 PMCID: PMC8269279 DOI: 10.3390/ijms22136924] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/10/2021] [Accepted: 06/24/2021] [Indexed: 01/07/2023] Open
Abstract
The pseudophosphatases, atypical members of the protein tyrosine phosphatase family, have emerged as bona fide signaling regulators within the past two decades. Their roles as regulators have led to a renaissance of the pseudophosphatase and pseudoenyme fields, catapulting interest from a mere curiosity to intriguing and relevant proteins to investigate. Pseudophosphatases make up approximately fourteen percent of the phosphatase family, and are conserved throughout evolution. Pseudophosphatases, along with pseudokinases, are important players in physiology and pathophysiology. These atypical members of the protein tyrosine phosphatase and protein tyrosine kinase superfamily, respectively, are rendered catalytically inactive through mutations within their catalytic active signature motif and/or other important domains required for catalysis. This new interest in the pursuit of the relevant functions of these proteins has resulted in an elucidation of their roles in signaling cascades and diseases. There is a rapid accumulation of knowledge of diseases linked to their dysregulation, such as neuropathies and various cancers. This review analyzes the involvement of pseudophosphatases in diseases, highlighting the function of various role(s) of pseudophosphatases involvement in pathologies, and thus providing a platform to strongly consider them as key therapeutic drug targets.
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13
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Berti B, Longo G, Mari F, Doccini S, Piccolo I, Donati MA, Moro F, Guerrini R, Santorelli FM, Petruzzella V. Bi-allelic variants in MTMR5/SBF1 cause Charcot-Marie-Tooth type 4B3 featuring mitochondrial dysfunction. BMC Med Genomics 2021; 14:157. [PMID: 34118926 PMCID: PMC8199524 DOI: 10.1186/s12920-021-01001-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 06/06/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) type 4B3 (CMT4B3) is a rare form of genetic neuropathy associated with variants in the MTMR5/SBF1 gene. MTMR5/SBF1 is a pseudophosphatase predicted to regulate endo-lysosomal trafficking in tandem with other MTMRs. Although almost ubiquitously expressed, pathogenic variants primarily impact on the peripheral nervous system, corroborating the involvement of MTMR5/SBF1 and its molecular partners in Schwann cells-mediated myelinization. CASE PRESENTATION We report a case of severe CMT4B3 characterized by early-onset motor and axonal polyneuropathy in an Italian child in absence of any evidence of brain and spine MRI abnormalities or intellectual disability and with a biochemical profile suggestive of mitochondrial disease. Using an integrated approach combining both NGS gene panels and WES analysis, we identified two novel compound heterozygous missense variants in MTMR5/SBF1 gene, p.R763H (c.2291G > A) and p.G1064E (c.3194G > A). Studies in muscle identified partial defects of oxidative metabolism. CONCLUSION We describe the first case of an early onset severe polyneuropathy with motor and axonal involvement, due to recessive variants in the MTMR5/SBF1 gene, with no evidence of brain and spine MRI abnormalities, intellectual disability, no clinical and neurophysiological evidences of distal sensory impairment, and rapid neuromuscular deterioration. This report suggests that MTMR5/SBF1 should be considered in cases of infantile-onset CMT with secondary mitochondrial dysfunction.
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Affiliation(s)
- Beatrice Berti
- Pediatric Neurology and Centro Clinico Nemo, Fondazione Policlinico Universitario Agostino Gemelli - IRCCS, Rome, Italy
| | - Giovanna Longo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Piazza G. Cesare, 11, 70124, Bari, Italy
| | - Francesco Mari
- Child Neurology Unit, Meyer Children's Hospital, Florence, Italy
| | - Stefano Doccini
- IRCCS Fondazione Stella Maris, via dei Giacinti 2, Calambrone, 56128, Pisa, Italy
| | - Ilaria Piccolo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Piazza G. Cesare, 11, 70124, Bari, Italy
| | | | - Francesca Moro
- IRCCS Fondazione Stella Maris, via dei Giacinti 2, Calambrone, 56128, Pisa, Italy
| | - Renzo Guerrini
- Child Neurology Unit, Meyer Children's Hospital, Florence, Italy
| | - Filippo M Santorelli
- IRCCS Fondazione Stella Maris, via dei Giacinti 2, Calambrone, 56128, Pisa, Italy.
| | - Vittoria Petruzzella
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Piazza G. Cesare, 11, 70124, Bari, Italy.
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14
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Genetic mechanisms of peripheral nerve disease. Neurosci Lett 2020; 742:135357. [PMID: 33249104 DOI: 10.1016/j.neulet.2020.135357] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/24/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022]
Abstract
Peripheral neuropathies of genetic etiology are a very diverse group of disorders manifesting either as non-syndromic inherited neuropathies without significant manifestations outside the peripheral nervous system, or as part of a systemic or syndromic genetic disorder. The former and most frequent group is collectively known as Charcot-Marie-Tooth disease (CMT), with prevalence as high as 1:2,500 world-wide, and has proven to be genetically highly heterogeneous. More than 100 different genes have been identified so far to cause various CMT forms, following all possible inheritance patterns. CMT causative genes belong to several common functional pathways that are essential for the integrity of the peripheral nerve. Their discovery has provided insights into the normal biology of axons and myelinating cells, and has highlighted the molecular mechanisms including both loss of function and gain of function effects, leading to peripheral nerve degeneration. Demyelinating neuropathies result from dysfunction of genes primarily affecting myelinating Schwann cells, while axonal neuropathies are caused by genes affecting mostly neurons and their long axons. Furthermore, mutation in genes expressed outside the nervous system, as in the case of inherited amyloid neuropathies, may cause peripheral neuropathy resulting from accumulation of β-structured amyloid fibrils in peripheral nerves in addition to various organs. Increasing insights into the molecular-genetic mechanisms have revealed potential therapeutic targets. These will enable the development of novel therapeutics for genetic neuropathies that remain, in their majority, without effective treatment.
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15
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Farré Mariné A, Granger N, Bertolani C, Mascort Boixeda J, Shelton GD, Luján Feliu‐Pascual A. Long-term outcome of Miniature Schnauzers with genetically confirmed demyelinating polyneuropathy: 12 cases. J Vet Intern Med 2020; 34:2005-2011. [PMID: 32738000 PMCID: PMC7517849 DOI: 10.1111/jvim.15861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/01/2020] [Accepted: 07/01/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND A demyelinating polyneuropathy with focally folded myelin sheaths was reported in 3 Miniature Schnauzers in France in 2008 and was predicted to represent a naturally occurring canine homologue of Charcot-Marie-Tooth (CMT) disease. A genetic variant of MTRM13/SBF2 has been identified as causative in affected Miniature Schnauzers with this polyneuropathy. OBJECTIVE To provide data on the long-term progression in affected Miniature Schnauzers from Spain confirmed with the MTRM13/SBF2 genetic variant. ANIMALS Twelve Miniature Schnauzers presented between March 2013 and June 2019. METHODS Only dogs presented with consistent clinical signs and homozygous for the MTRM13/SBF2 genetic variant were included. Clinical signs, age of onset and presentation, time from onset to presentation, treatment, outcome, and time from diagnosis to final follow-up were retrospectively reviewed. RESULTS The hallmark clinical signs at the time of presentation were regurgitation with radiologically confirmed megaesophagus (11/12) and aphonic bark (11/12) with or without obvious neuromuscular weakness despite electrodiagnostic evidence of appendicular demyelinating polyneuropathy. Age of onset and clinical presentation were 3-18 and 4-96 months, respectively. Treatment was mostly symptomatic and consisted of head elevation during meals, antacids, prokinetics, bethanechol, sildenafil, mirtazapine, or some combination of these. During the follow-up period (7-73 months), clinical signs were unchanged in (11/12) cases with aspiration pneumonia developing occasionally (6/12) and being the cause of death in 1 dog. CONCLUSIONS AND CLINICAL IMPORTANCE Demyelinating polyneuropathy of Miniature Schnauzers tends to remain stable over the long term leading to a good prognosis with preventive feeding measures and symptomatic treatment to control aspiration pneumonia.
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Affiliation(s)
| | - Nicolas Granger
- CVS Referrals, Bristol Veterinary Specialists at HighcroftBristolUK
- The Royal Veterinary College, University of LondonHatfieldUK
| | | | | | - G. Diane Shelton
- Department of Pathology, School of MedicineUniversity of California and Comparative Neuromuscular LaboratorySan DiegoCaliforniaUSA
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16
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Guimarães-Costa R, Villar-Quiles RN, Latour P, Sole G, Husson I, Lacour A, Leonard-Louis S, Stojkovic T. Confounding clinical presentation and different disease progression in CMT4B1. Neuromuscul Disord 2020; 30:576-582. [DOI: 10.1016/j.nmd.2020.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/30/2020] [Accepted: 05/07/2020] [Indexed: 11/27/2022]
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17
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Sawade L, Grandi F, Mignanelli M, Patiño-López G, Klinkert K, Langa-Vives F, Di Guardo R, Echard A, Bolino A, Haucke V. Rab35-regulated lipid turnover by myotubularins represses mTORC1 activity and controls myelin growth. Nat Commun 2020; 11:2835. [PMID: 32503983 PMCID: PMC7275063 DOI: 10.1038/s41467-020-16696-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 05/18/2020] [Indexed: 01/21/2023] Open
Abstract
Inherited peripheral neuropathies (IPNs) represent a broad group of disorders including Charcot-Marie-Tooth (CMT) neuropathies characterized by defects primarily arising in myelin, axons, or both. The molecular mechanisms by which mutations in nearly 100 identified IPN/CMT genes lead to neuropathies are poorly understood. Here we show that the Ras-related GTPase Rab35 controls myelin growth via complex formation with the myotubularin-related phosphatidylinositol (PI) 3-phosphatases MTMR13 and MTMR2, encoded by genes responsible for CMT-types 4B2 and B1 in humans, and found that it downregulates lipid-mediated mTORC1 activation, a pathway known to crucially regulate myelin biogenesis. Targeted disruption of Rab35 leads to hyperactivation of mTORC1 signaling caused by elevated levels of PI 3-phosphates and to focal hypermyelination in vivo. Pharmacological inhibition of phosphatidylinositol 3,5-bisphosphate synthesis or mTORC1 signaling ameliorates this phenotype. These findings reveal a crucial role for Rab35-regulated lipid turnover by myotubularins to repress mTORC1 activity and to control myelin growth. Charcot-Marie-Tooth (CMT) is an inherited peripheral neuropathy. Here, the authors show that Rab35 forms a complex with genes implicated in CMT, MTMR13 and MTMR2, which regulates myelin growth by controlling mTORC1 signaling through lipid turnover.
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Affiliation(s)
- Linda Sawade
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125, Berlin, Germany
| | - Federica Grandi
- Institute of Experimental Neurology (InSpe), Division of Neuroscience, IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy
| | - Marianna Mignanelli
- Institute of Experimental Neurology (InSpe), Division of Neuroscience, IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy.,San Raffaele Vita-Salute University, Via Olgettina 60, 20132, Milan, Italy
| | - Genaro Patiño-López
- Laboratorio de Investigación en Inmunología y Proteómica, Hospital Infantil de México, Federico Gómez. C.P, 06720, Ciudad de México, México
| | - Kerstin Klinkert
- Membrane Traffic and Cell Division Lab, Institut Pasteur, UMR3691, CNRS, 25-28 rue du Dr Roux, F-75015, Paris, France.,Sorbonne Université, Collège doctoral, F-75005, Paris, France
| | - Francina Langa-Vives
- Centre d'Ingénierie Génétique Murine, Institut Pasteur, 25-28 rue du Dr Roux, F-75015, Paris, France
| | - Roberta Di Guardo
- Institute of Experimental Neurology (InSpe), Division of Neuroscience, IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy
| | - Arnaud Echard
- Membrane Traffic and Cell Division Lab, Institut Pasteur, UMR3691, CNRS, 25-28 rue du Dr Roux, F-75015, Paris, France
| | - Alessandra Bolino
- Institute of Experimental Neurology (InSpe), Division of Neuroscience, IRCCS Ospedale San Raffaele, Via Olgettina 60, 20132, Milan, Italy.
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125, Berlin, Germany. .,Freie Universität Berlin, Faculty of Biology, Chemistry and Pharmacy, 14195, Berlin, Germany. .,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt- Universität zu Berlin, NeuroCure Cluster of Excellence, 10117, Berlin, Germany.
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18
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A novel frameshift deletion in autosomal recessive SBF1-related syndromic neuropathy with necklace fibres. J Neurol 2020; 267:2705-2712. [PMID: 32444983 PMCID: PMC7419361 DOI: 10.1007/s00415-020-09827-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/03/2020] [Accepted: 04/06/2020] [Indexed: 11/29/2022]
Abstract
Objective To identify the genetic cause of complex neuropathy in two siblings from a consanguineous family. Methods The patients were recruited from our clinic. Muscle biopsy and whole-exome sequencing (WES) were performed. Fibroblasts cell lines from the index patient, unaffected parents, and three normal controls were used for cDNA analysis and western blot. Results The index patient was a 29-year-old male with clinical phenotype of syndactyly, pes cavus, swallowing difficulties, vision problem, imbalance, and muscle weakness. The sibling had similar, but milder symptoms. Nerve conduction studies and electromyography of both patients suggested sensory-motor axonal neuropathy. Muscle biopsy showed a feature of necklace fibres. WES identified a novel homozygous frameshift deletion (c.5477-5478del; p.1826-1826del) in exon 40 of the SBF1 gene in the two siblings, while both parents and the unaffected sibling were heterozygous carriers. Functional analysis showed a markedly reduced level of MTMR5 protein encoded by SBF1 in the index case. The levels of MTMR5 protein in unaffected parents were similar to those found in controls. Conclusion A novel homozygous frameshift deletion in SBF1 was identified in this family. Sensory-motor axonal neuropathy and necklace fibres in biopsy were the major features expanding the phenotypic spectrum of SBF1-related recessive syndromic neuropathy. Electronic supplementary material The online version of this article (10.1007/s00415-020-09827-y) contains supplementary material, which is available to authorized users.
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19
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Granger N, Luján Feliu-Pascual A, Spicer C, Ricketts S, Hitti R, Forman O, Hersheson J, Houlden H. Charcot-Marie-Tooth type 4B2 demyelinating neuropathy in miniature Schnauzer dogs caused by a novel splicing SBF2 (MTMR13) genetic variant: a new spontaneous clinical model. PeerJ 2019; 7:e7983. [PMID: 31772832 PMCID: PMC6875392 DOI: 10.7717/peerj.7983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 10/02/2019] [Indexed: 01/23/2023] Open
Abstract
Background Charcot-Marie-Tooth (CMT) disease is the most common neuromuscular disorder in humans affecting 40 out of 100,000 individuals. In 2008, we described the clinical, electrophysiological and pathological findings of a demyelinating motor and sensory neuropathy in Miniature Schnauzer dogs, with a suspected autosomal recessive mode of inheritance based on pedigree analysis. The discovery of additional cases has followed this work and led to a genome-wide association mapping approach to search for the underlying genetic cause of the disease. Methods For genome wide association screening, genomic DNA samples from affected and unaffected dogs were genotyped using the Illumina CanineHD SNP genotyping array. SBF2 and its variant were sequenced using primers and PCRs. RNA was extracted from muscle of an unaffected and an affected dog and RT-PCR performed. Immunohistochemistry for myelin basic protein was performed on peripheral nerve section specimens. Results The genome-wide association study gave an indicative signal on canine chromosome 21. Although the signal was not of genome-wide significance due to the small number of cases, the SBF2 (also known as MTMR13) gene within the region of shared case homozygosity was a strong positional candidate, as 22 genetic variants in the gene have been associated with demyelinating forms of Charcot-Marie-Tooth disease in humans. Sequencing of SBF2 in cases revealed a splice donor site genetic variant, resulting in cryptic splicing and predicted early termination of the protein based on RNA sequencing results. Conclusions This study reports the first genetic variant in Miniature Schnauzer dogs responsible for the occurrence of a demyelinating peripheral neuropathy with abnormally folded myelin. This discovery establishes a genotype/phenotype correlation in affected Miniature Schnauzers that can be used for the diagnosis of these dogs. It further supports the dog as a natural model of a human disease; in this instance, Charcot-Marie-Tooth disease. It opens avenues to search the biological mechanisms responsible for the disease and to test new therapies in a non-rodent large animal model. In particular, recent gene editing methods that led to the restoration of dystrophin expression in a canine model of muscular dystrophy could be applied to other canine models such as this before translation to humans.
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Affiliation(s)
- Nicolas Granger
- Royal Veterinary College, University of London, Hatfield, United Kingdom.,Bristol Veterinary Specialists, CVS Referrals, Bristol, United Kingdom
| | | | - Charlotte Spicer
- Department of Molecular Neuroscience, UCL Institute of Neurology & National Hospital for Neurology and Neurosurgery & London, London, United Kingdom
| | - Sally Ricketts
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, United Kingdom
| | - Rebekkah Hitti
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, United Kingdom
| | - Oliver Forman
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, United Kingdom
| | - Joshua Hersheson
- Department of Molecular Neuroscience, UCL Institute of Neurology & National Hospital for Neurology and Neurosurgery & London, London, United Kingdom
| | - Henry Houlden
- Department of Molecular Neuroscience, UCL Institute of Neurology & National Hospital for Neurology and Neurosurgery & London, London, United Kingdom
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20
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Wang H, Kaçar Bayram A, Sprute R, Ozdemir O, Cooper E, Pergande M, Efthymiou S, Nedic I, Mazaheri N, Stumpfe K, Azizi Malamiri R, Shariati G, Zeighami J, Bayram N, Naghibzadeh SK, Tajik M, Yaşar M, Sami Güven A, Bibi F, Sultan T, Salpietro V, Houlden H, Per H, Galehdari H, Shalbafan B, Jamshidi Y, Cirak S. Genotype-Phenotype Correlations in Charcot-Marie-Tooth Disease Due to MTMR2 Mutations and Implications in Membrane Trafficking. Front Neurosci 2019; 13:974. [PMID: 31680794 PMCID: PMC6807680 DOI: 10.3389/fnins.2019.00974] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 08/30/2019] [Indexed: 11/13/2022] Open
Abstract
Charcot-Marie-Tooth type 4 (CMT4) is an autosomal recessive severe form of neuropathy with genetic heterogeneity. CMT4B1 is caused by mutations in the myotubularin-related 2 (MTMR2) gene and as a member of the myotubularin family, the MTMR2 protein is crucial for the modulation of membrane trafficking. To enable future clinical trials, we performed a detailed review of the published cases with MTMR2 mutations and describe four novel cases identified through whole-exome sequencing (WES). The four unrelated families harbor novel homozygous mutations in MTMR2 (NM_016156, Family 1: c.1490dupC; p.Phe498IlefsTer2; Family 2: c.1479+1G>A; Family 3: c.1090C>T; p.Arg364Ter; Family 4: c.883C>T; p.Arg295Ter) and present with CMT4B1-related severe early-onset motor and sensory neuropathy, generalized muscle atrophy, facial and bulbar weakness, and pes cavus deformity. The clinical description of the new mutations reported here overlap with previously reported CMT4B1 phenotypes caused by mutations in the phosphatase domain of MTMR2, suggesting that nonsense MTMR2 mutations, which are predicted to result in loss or disruption of the phosphatase domain, are associated with a severe phenotype and loss of independent ambulation by the early twenties. Whereas the few reported missense mutations and also those truncating mutations occurring at the C-terminus after the phosphatase domain cause a rather mild phenotype and patients were still ambulatory above the age 30 years. Charcot-Marie-Tooth neuropathy and Centronuclear Myopathy causing mutations have been shown to occur in proteins involved in membrane remodeling and trafficking pathway mediated by phosphoinositides. Earlier studies have showing the rescue of MTM1 myopathy by MTMR2 overexpression, emphasize the importance of maintaining the phosphoinositides equilibrium and highlight a potential compensatory mechanism amongst members of this pathway. This proved that the regulation of expression of these proteins involved in the membrane remodeling pathway may compensate each other's loss- or gain-of-function mutations by restoring the phosphoinositides equilibrium. This provides a potential therapeutic strategy for neuromuscular diseases resulting from mutations in the membrane remodeling pathway.
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Affiliation(s)
- Haicui Wang
- Department of Pediatrics, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany
| | - Ayşe Kaçar Bayram
- Department of Pediatric Neurology, University of Health Sciences, Kayseri City Hospital, Kayseri, Turkey
| | - Rosanne Sprute
- Department of Pediatrics, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany
| | - Ozkan Ozdemir
- Department of Pediatrics, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany
| | - Emily Cooper
- Genetics Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, United Kingdom
| | - Matthias Pergande
- Department of Pediatrics, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, United Kingdom
| | - Ivana Nedic
- Genetics Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, United Kingdom
| | - Neda Mazaheri
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Iran.,Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Katharina Stumpfe
- Department of Pediatrics, University Hospital Cologne, Cologne, Germany
| | - Reza Azizi Malamiri
- Paediatric Neurology, Department of Paediatric Neurology, Golestan Medical, Educational, and Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Gholamreza Shariati
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Iran.,Department of Medical Genetics, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Jawaher Zeighami
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Iran
| | - Nurettin Bayram
- Department of Ophthalmology, University of Health Sciences, Kayseri City Hospital, Kayseri, Turkey
| | | | - Mohamad Tajik
- Department of Neurology, Firoozgar General Hospital, University of Medical Sciences, Tehran, Iran
| | - Mehmet Yaşar
- Department of Ear Nose and Throat, University of Health Sciences, Kayseri City Hospital, Kayseri, Turkey
| | - Ahmet Sami Güven
- Department of Pediatric Neurology, Meram Medical Faculty, Necmettin Erbakan University, Konya, Turkey
| | - Farah Bibi
- Institute of Biochemistry and Biotechnology, PMAS Arid Agriculture University, Rawalpindi, Pakistan
| | - Tipu Sultan
- Department of Pediatric Neurology, Institute of Child Health, The Children's Hospital Lahore, Lahore, Pakistan
| | - Vincenzo Salpietro
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, United Kingdom.,Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Henry Houlden
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, United Kingdom
| | - Hüseyin Per
- Department of Pediatric Neurology, Erciyes University Medical School, Kayseri, Turkey
| | - Hamid Galehdari
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Bita Shalbafan
- Iran Social Security Organization, Labafinejad Hospital, Tehran, Iran
| | - Yalda Jamshidi
- Genetics Research Centre, Molecular and Clinical Sciences Institute, St. George's, University of London, London, United Kingdom
| | - Sebahattin Cirak
- Department of Pediatrics, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine (CMMC), University of Cologne, Cologne, Germany
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Robinson DC, Mammel AE, Logan AM, Larson AA, Schmidt EJ, Condon AF, Robinson FL. An In Vitro Model of Charcot-Marie-Tooth Disease Type 4B2 Provides Insight Into the Roles of MTMR13 and MTMR2 in Schwann Cell Myelination. ASN Neuro 2019; 10:1759091418803282. [PMID: 30419760 PMCID: PMC6236487 DOI: 10.1177/1759091418803282] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Charcot-Marie-Tooth Disorder Type 4B (CMT4B) is a demyelinating
peripheral neuropathy caused by mutations in myotubularin-related
(MTMR) proteins 2, 13, or 5 (CMT4B1/2/3), which regulate
phosphoinositide turnover and endosomal trafficking. Although mouse
models of CMT4B2 exist, an in vitro model would make
possible pharmacological and reverse genetic experiments needed to
clarify the role of MTMR13 in myelination. We have generated such a
model using Schwann cell-dorsal root ganglion (SC-DRG) explants from
Mtmr13−/− mice. Myelin sheaths
in mutant cultures contain outfoldings highly reminiscent of those
observed in the nerves of Mtmr13−/− mice
and CMT4B2 patients. Mtmr13−/− SC-DRG
explants also contain reduced Mtmr2, further supporting a role of
Mtmr13 in stabilizing Mtmr2. Elevated PI(3,5)P2 has been
implicated as a cause of myelin outfoldings in
Mtmr2−/− models. In contrast,
the role of elevated PI3P or PI(3,5)P2 in promoting
outfoldings in Mtmr13−/− models is
unclear. We found that over-expression of MTMR2 in
Mtmr13−/− SC-DRGs moderately
reduced the prevalence of myelin outfoldings. Thus, a manipulation
predicted to lower PI3P and PI(3,5)P2 partially suppressed
the phenotype caused by Mtmr13 deficiency. We also explored the
relationship between CMT4B2-like myelin outfoldings and kinases that
produce PI3P and PI(3,5)P2 by analyzing nerve pathology in
mice lacking both Mtmr13 and one of two specific PI 3-kinases.
Intriguingly, the loss of vacuolar protein sorting 34 or PI3K-C2β in
Mtmr13−/− mice had no impact
on the prevalence of myelin outfoldings. In aggregate, our findings
suggest that the MTMR13 scaffold protein likely has critical functions
other than stabilizing MTMR2 to achieve an adequate level of PI
3-phosphatase activity.
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Affiliation(s)
- Danielle C Robinson
- 1 Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA.,2 Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR, USA
| | - Anna E Mammel
- 1 Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA.,3 Cell, Developmental & Cancer Biology Graduate Program, Oregon Health & Science University, Portland, OR, USA
| | - Anne M Logan
- 1 Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA.,2 Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR, USA
| | - Aubree A Larson
- 1 Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA
| | - Eric J Schmidt
- 1 Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA
| | - Alec F Condon
- 1 Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA.,2 Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR, USA
| | - Fred L Robinson
- 1 Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR, USA.,4 Vollum Institute, Oregon Health & Science University, Portland, OR, USA
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22
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Pareyson D, Stojkovic T, Reilly MM, Leonard-Louis S, Laurà M, Blake J, Parman Y, Battaloglu E, Tazir M, Bellatache M, Bonello-Palot N, Lévy N, Sacconi S, Guimarães-Costa R, Attarian S, Latour P, Solé G, Megarbane A, Horvath R, Ricci G, Choi BO, Schenone A, Gemelli C, Geroldi A, Sabatelli M, Luigetti M, Santoro L, Manganelli F, Quattrone A, Valentino P, Murakami T, Scherer SS, Dankwa L, Shy ME, Bacon CJ, Herrmann DN, Zambon A, Tramacere I, Pisciotta C, Magri S, Previtali SC, Bolino A. A multicenter retrospective study of charcot-marie-tooth disease type 4B (CMT4B) associated with mutations in myotubularin-related proteins (MTMRs). Ann Neurol 2019; 86:55-67. [PMID: 31070812 DOI: 10.1002/ana.25500] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 04/23/2019] [Accepted: 05/05/2019] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Charcot-Marie-Tooth (CMT) disease 4B1 and 4B2 (CMT4B1/B2) are characterized by recessive inheritance, early onset, severe course, slowed nerve conduction, and myelin outfoldings. CMT4B3 shows a more heterogeneous phenotype. All are associated with myotubularin-related protein (MTMR) mutations. We conducted a multicenter, retrospective study to better characterize CMT4B. METHODS We collected clinical and genetic data from CMT4B subjects in 18 centers using a predefined minimal data set including Medical Research Council (MRC) scores of nine muscle pairs and CMT Neuropathy Score. RESULTS There were 50 patients, 21 of whom never reported before, carrying 44 mutations, of which 21 were novel and six representing novel disease associations of known rare variants. CMT4B1 patients had significantly more-severe disease than CMT4B2, with earlier onset, more-frequent motor milestones delay, wheelchair use, and respiratory involvement as well as worse MRC scores and motor CMT Examination Score components despite younger age at examination. Vocal cord involvement was common in both subtypes, whereas glaucoma occurred in CMT4B2 only. Nerve conduction velocities were similarly slowed in both subtypes. Regression analyses showed that disease severity is significantly associated with age in CMT4B1. Slopes are steeper for CMT4B1, indicating faster disease progression. Almost none of the mutations in the MTMR2 and MTMR13 genes, responsible for CMT4B1 and B2, respectively, influence the correlation between disease severity and age, in agreement with the hypothesis of a complete loss of function of MTMR2/13 proteins for such mutations. INTERPRETATION This is the largest CMT4B series ever reported, demonstrating that CMT4B1 is significantly more severe than CMT4B2, and allowing an estimate of prognosis. ANN NEUROL 2019.
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Affiliation(s)
- Davide Pareyson
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Tanya Stojkovic
- Hôpital Pitié-Salpêtrière, AP-HP, Centre de référence des maladies neuromusculaires Nord/Est/Ile de France, Paris, France
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Sarah Leonard-Louis
- Hôpital Pitié-Salpêtrière, AP-HP, Centre de référence des maladies neuromusculaires Nord/Est/Ile de France, Paris, France
| | - Matilde Laurà
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Julian Blake
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom.,Department of Clinical Neurophysiology, Norfolk and Norwich University Hospital, Norfolk, United Kingdom
| | - Yesim Parman
- Istanbul University, Istanbul Faculty of Medicine, Neurology Dep. Istanbul, Turkey
| | - Esra Battaloglu
- Bogazici University, Department of Molecular Biology and Genetics, Istanbul, Turkey
| | - Meriem Tazir
- Laboratoire de Recherche en Neurosciences Service de Neurologie, CHU, Alger, Algeria
| | - Mounia Bellatache
- Laboratoire de Recherche en Neurosciences Service de Neurologie, CHU, Alger, Algeria
| | - Nathalie Bonello-Palot
- Department of Medical Genetics, Timone Hospital, Marseille, France.2, Aix-Marseille University, INSERM, MMG, U1251, Marseille, France
| | - Nicolas Lévy
- Department of Medical Genetics, Timone Hospital, Marseille, France.2, Aix-Marseille University, INSERM, MMG, U1251, Marseille, France
| | - Sabrina Sacconi
- Université Côte d'Azur, Service Système Nerveux Périphérique, Muscle et SLA, Centre Hospitalier Universitaire de Nice, Nice, France
| | - Raquel Guimarães-Costa
- Hôpital Pitié-Salpêtrière, AP-HP, Centre de référence des maladies neuromusculaires Nord/Est/Ile de France, Paris, France
| | - Sharham Attarian
- Reference center for neuromuscular disorders and ALS, CHU La Timone, Aix-Marseille University, Marseille, France
| | - Philippe Latour
- Center of Biology and Pathology Laboratory of Molecular Neurogenetics, Hospices Civils, Lyon, France
| | - Guilhem Solé
- Reference center for neuromuscular disorders AOC (Atlantique Occitanie Caraibes), CHU de Bordeaux, Bordeaux, France
| | - André Megarbane
- Institut Jérôme Lejeune, Paris, France.,INOVIE, Beirut, Lebanon
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom.,Institute of Genetic Medicine, Newcastle University, Newcastle, United Kingdom
| | - Giulia Ricci
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom.,Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Byung-Ok Choi
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Angelo Schenone
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and MATERNAL Infantile Sciences, University of Genoa, and IRCCS Policlinico San Martino, Genoa, Italy
| | - Chiara Gemelli
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and MATERNAL Infantile Sciences, University of Genoa, and IRCCS Policlinico San Martino, Genoa, Italy
| | - Alessandro Geroldi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetic and MATERNAL Infantile Sciences, University of Genoa, and IRCCS Policlinico San Martino, Genoa, Italy
| | - Mario Sabatelli
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS. Centro Clinico Nemo Adulti Rome, Rome, Italy.,Università Cattolica del Sacro Cuore. Sede di Roma, Rome, Italy
| | - Marco Luigetti
- Università Cattolica del Sacro Cuore. Sede di Roma, Rome, Italy.,UOC Neurologia, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy
| | - Lucio Santoro
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Naples, Italy
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Naples, Italy
| | - Aldo Quattrone
- Department of Neurology, Università Magna Graecia di Catanzaro, Catanzaro, Italy
| | - Paola Valentino
- Department of Neurology, Università Magna Graecia di Catanzaro, Catanzaro, Italy
| | | | - Steven S Scherer
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Lois Dankwa
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Michael E Shy
- Department of Neurology, University of Iowa Hospitals and Clinics, Iowa, IA
| | - Chelsea J Bacon
- Department of Neurology, University of Iowa Hospitals and Clinics, Iowa, IA
| | | | - Alberto Zambon
- Institute of Experimental Neurology (InSpe), Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Irene Tramacere
- Department of Research and Clinical Development, Scientific Directorate, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Pisciotta
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Stefania Magri
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Stefano C Previtali
- Institute of Experimental Neurology (InSpe), Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Alessandra Bolino
- Institute of Experimental Neurology (InSpe), Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
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Hinton SD. The role of pseudophosphatases as signaling regulators. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:167-174. [PMID: 30077638 DOI: 10.1016/j.bbamcr.2018.07.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/23/2018] [Accepted: 07/27/2018] [Indexed: 12/13/2022]
Abstract
Pseudophosphatases are atypical members of the protein tyrosine phosphatase superfamily. Mutations within their catalytic signature motif render them catalytically inactive. Despite this lack of catalytic function, pseudophosphatases have been implicated in various diseases such as Charcot Marie-Tooth disorder, cancer, metabolic disorder, and obesity. Moreover, they have roles in various signaling networks such as spermatogenesis, apoptosis, stress response, tumorigenesis, and neurite differentiation. This review highlights the roles of pseudophosphatases as essential regulators in signaling cascades, providing insight into the function of these catalytically inactive enzymes.
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Affiliation(s)
- Shantá D Hinton
- Department of Biology, Integrated Science Center, College of William and Mary, Williamsburg, VA, USA.
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24
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Stassart RM, Möbius W, Nave KA, Edgar JM. The Axon-Myelin Unit in Development and Degenerative Disease. Front Neurosci 2018; 12:467. [PMID: 30050403 PMCID: PMC6050401 DOI: 10.3389/fnins.2018.00467] [Citation(s) in RCA: 131] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 06/19/2018] [Indexed: 12/15/2022] Open
Abstract
Axons are electrically excitable, cable-like neuronal processes that relay information between neurons within the nervous system and between neurons and peripheral target tissues. In the central and peripheral nervous systems, most axons over a critical diameter are enwrapped by myelin, which reduces internodal membrane capacitance and facilitates rapid conduction of electrical impulses. The spirally wrapped myelin sheath, which is an evolutionary specialisation of vertebrates, is produced by oligodendrocytes and Schwann cells; in most mammals myelination occurs during postnatal development and after axons have established connection with their targets. Myelin covers the vast majority of the axonal surface, influencing the axon's physical shape, the localisation of molecules on its membrane and the composition of the extracellular fluid (in the periaxonal space) that immerses it. Moreover, myelinating cells play a fundamental role in axonal support, at least in part by providing metabolic substrates to the underlying axon to fuel its energy requirements. The unique architecture of the myelinated axon, which is crucial to its function as a conduit over long distances, renders it particularly susceptible to injury and confers specific survival and maintenance requirements. In this review we will describe the normal morphology, ultrastructure and function of myelinated axons, and discuss how these change following disease, injury or experimental perturbation, with a particular focus on the role the myelinating cell plays in shaping and supporting the axon.
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Affiliation(s)
- Ruth M. Stassart
- Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
- Department of Neuropathology, University Medical Center Leipzig, Leipzig, Germany
| | - Wiebke Möbius
- Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
| | - Julia M. Edgar
- Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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25
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Narayanan P, Hütte M, Kudryasheva G, Taberner FJ, Lechner SG, Rehfeldt F, Gomez-Varela D, Schmidt M. Myotubularin related protein-2 and its phospholipid substrate PIP 2 control Piezo2-mediated mechanotransduction in peripheral sensory neurons. eLife 2018. [PMID: 29521261 PMCID: PMC5898911 DOI: 10.7554/elife.32346] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Piezo2 ion channels are critical determinants of the sense of light touch in vertebrates. Yet, their regulation is only incompletely understood. We recently identified myotubularin related protein-2 (Mtmr2), a phosphoinositide (PI) phosphatase, in the native Piezo2 interactome of murine dorsal root ganglia (DRG). Here, we demonstrate that Mtmr2 attenuates Piezo2-mediated rapidly adapting mechanically activated (RA-MA) currents. Interestingly, heterologous Piezo1 and other known MA current subtypes in DRG appeared largely unaffected by Mtmr2. Experiments with catalytically inactive Mtmr2, pharmacological blockers of PI(3,5)P2 synthesis, and osmotic stress suggest that Mtmr2-dependent Piezo2 inhibition involves depletion of PI(3,5)P2. Further, we identified a PI(3,5)P2 binding region in Piezo2, but not Piezo1, that confers sensitivity to Mtmr2 as indicated by functional analysis of a domain-swapped Piezo2 mutant. Altogether, our results propose local PI(3,5)P2 modulation via Mtmr2 in the vicinity of Piezo2 as a novel mechanism to dynamically control Piezo2-dependent mechanotransduction in peripheral sensory neurons. We often take our sense of touch for granted. Yet, our every-day life greatly depends on the ability to perceive our environment to alert us of danger or to further social interactions, such as mother-child bonding. Our sense of touch relies on the conversion of mechanical stimuli to electrical signals (this is known as mechanotransduction), which then travel to brain to be processed. This task is fulfilled by specific ion channels called Piezo2, which are activated when cells are exposed to pressure and other mechanical forces. These channels can be found in sensory nerves and specialized structures in the skin, where they help to detect physical contact, roughness of surfaces and the position of our body parts. It is still not clear how Piezo2 channels are regulated but previous research by several laboratories suggests that they work in conjunction with other proteins. One of these proteins is the myotubularin related protein-2, or Mtmr2 for short. Now, Narayanan et al. – including some of the researchers involved in the previous research – set out to advance our understanding of the molecular basis of touch and looked more closely at Mtmr2. To test if Mtmr2 played a role in mechanotransduction, Narayanan et al. both increased and reduced the levels of this protein in sensory neurons of mice grown in the laboratory. When Mtmr2 levels were low, the activity of Piezo2 channels increased. However, when the protein levels were high, Piezo2 channels were inhibited. These results suggest that Mtmr2 can control the activity of Piezo2. Further experiments, in which Mtmr2 was genetically modified or sensory neurons were treated with chemicals, revealed that Mtmr2 reduces a specific fatty acid in the membrane of nerve cells, which in turn attenuates the activity of Piezo2. This study identified Mtmr2 and distinct fatty acids in the cell membrane as new components of the complex setup required for the sense of touch. A next step will be to test if these molecules also influence the activity of Piezo2 when the skin has become injured or upon inflammation.
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Affiliation(s)
- Pratibha Narayanan
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
| | - Meike Hütte
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
| | - Galina Kudryasheva
- Third Institute of Physics - Biophysics, University of Goettingen, Goettingen, Germany
| | | | | | - Florian Rehfeldt
- Third Institute of Physics - Biophysics, University of Goettingen, Goettingen, Germany
| | - David Gomez-Varela
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
| | - Manuela Schmidt
- Emmy Noether-Group Somatosensory Signaling and Systems Biology, Max Planck Institute for Experimental Medicine, Goettingen, Germany
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26
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Juszczak GR, Stankiewicz AM. Glucocorticoids, genes and brain function. Prog Neuropsychopharmacol Biol Psychiatry 2018; 82:136-168. [PMID: 29180230 DOI: 10.1016/j.pnpbp.2017.11.020] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/18/2017] [Accepted: 11/23/2017] [Indexed: 01/02/2023]
Abstract
The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.
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Affiliation(s)
- Grzegorz R Juszczak
- Department of Animal Behavior, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland.
| | - Adrian M Stankiewicz
- Department of Molecular Biology, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland
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27
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Whole-Exome Sequencing Identifies a Novel Homozygous Frameshift Mutation in the MTMR2 Gene as a Causative Mutation in a Patient with Charcot-Marie-Tooth Disease Type 4B1. Mol Neurobiol 2017; 55:3546-3550. [DOI: 10.1007/s12035-017-0588-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 04/28/2017] [Indexed: 01/08/2023]
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28
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Antagonistic roles for STYX pseudophosphatases in neurite outgrowth. Biochem Soc Trans 2017; 45:381-387. [PMID: 28408478 DOI: 10.1042/bst20160273] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/17/2017] [Accepted: 01/20/2017] [Indexed: 12/14/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) are essential players in important neuronal signaling pathways including neuronal development, plasticity, survival, learning, and memory. The inactivation of MAPKs is tightly controlled by MAPK phosphatases (MKPs), which also are important regulators of these neuronal processes. Considering that MAPKs and MKPs are major players in neuronal signaling, it follows that their misregulation is pivotal in neurodegenerative diseases such as Alzheimer's, Huntington's, Parkinson's, and amyotrophic lateral sclerosis. In contrast, the actions of their noncatalytic homologs, or pseudoenzymes, have received minimal attention as important regulators in neuronal signaling pathways and relevant diseases. There is compelling evidence, however, that pseudophosphatases, such as STYX (phospho-serine-threonine/tyrosine-binding protein) and MAPK-STYX (MK-STYX), are integral signaling molecules in regulating pathways involved in neuronal developmental processes such as neurite outgrowth. Here, we discuss how the dynamics of MK-STYX in the stress response pathway imply that this unique member of the MKP subfamily has the potential to have a major role in neuronal signaling. We further compare the actions of STYX in preventing neurite-like outgrowths and MK-STYX in inducing neurite outgrowths. The roles of these pseudophosphatases in neurite outgrowth highlight their emergence as important candidates to investigate in neurodegenerative disorders and diseases.
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29
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Bolino A, Piguet F, Alberizzi V, Pellegatta M, Rivellini C, Guerrero-Valero M, Noseda R, Brombin C, Nonis A, D'Adamo P, Taveggia C, Previtali SC. Niacin-mediated Tace activation ameliorates CMT neuropathies with focal hypermyelination. EMBO Mol Med 2016; 8:1438-1454. [PMID: 27799291 PMCID: PMC5167133 DOI: 10.15252/emmm.201606349] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Charcot–Marie–Tooth (CMT) neuropathies are highly heterogeneous disorders caused by mutations in more than 70 genes, with no available treatment. Thus, it is difficult to envisage a single suitable treatment for all pathogenetic mechanisms. Axonal Neuregulin 1 (Nrg1) type III drives Schwann cell myelination and determines myelin thickness by ErbB2/B3‐PI3K–Akt signaling pathway activation. Nrg1 type III is inhibited by the α‐secretase Tace, which negatively regulates PNS myelination. We hypothesized that modulation of Nrg1 levels and/or secretase activity may constitute a unifying treatment strategy for CMT neuropathies with focal hypermyelination as it could restore normal levels of myelination. Here we show that in vivo delivery of Niaspan, a FDA‐approved drug known to enhance TACE activity, efficiently rescues myelination in the Mtmr2−/− mouse, a model of CMT4B1 with myelin outfoldings, and in the Pmp22+/− mouse, which reproduces HNPP (hereditary neuropathy with liability to pressure palsies) with tomacula. Importantly, we also found that Niaspan reduces hypermyelination of Vim (vimentin)−/− mice, characterized by increased Nrg1 type III and Akt activation, thus corroborating the hypothesis that Niaspan treatment downregulates Nrg1 type III signaling.
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Affiliation(s)
- Alessandra Bolino
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy .,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Françoise Piguet
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Valeria Alberizzi
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Marta Pellegatta
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Cristina Rivellini
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Marta Guerrero-Valero
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Roberta Noseda
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Chiara Brombin
- University Centre of Statistics in the Biomedical Sciences (CUSSB), Vita-Salute San Raffaele University, Milan, Italy
| | - Alessandro Nonis
- University Centre of Statistics in the Biomedical Sciences (CUSSB), Vita-Salute San Raffaele University, Milan, Italy
| | - Patrizia D'Adamo
- Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Carla Taveggia
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Stefano Carlo Previtali
- INSPE-Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.,Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy.,Department of Neurology, San Raffaele Scientific Institute, Milan, Italy
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30
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Monk KR, Feltri ML, Taveggia C. New insights on Schwann cell development. Glia 2015; 63:1376-93. [PMID: 25921593 PMCID: PMC4470834 DOI: 10.1002/glia.22852] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/13/2015] [Indexed: 12/11/2022]
Abstract
In the peripheral nervous system, Schwann cells are glial cells that are in intimate contact with axons throughout development. Schwann cells generate the insulating myelin sheath and provide vital trophic support to the neurons that they ensheathe. Schwann cell precursors arise from neural crest progenitor cells, and a highly ordered developmental sequence controls the progression of these cells to become mature myelinating or nonmyelinating Schwann cells. Here, we discuss both seminal discoveries and recent advances in our understanding of the molecular mechanisms that drive Schwann cell development and myelination with a focus on cell-cell and cell-matrix signaling events.
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Affiliation(s)
- Kelly R Monk
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri
| | - M Laura Feltri
- Department of Biochemistry and Neurology, Hunter James Kelly Research Institute, University at Buffalo, State University of New York, Buffalo, New York
| | - Carla Taveggia
- Division of Neuroscience and INSPE, San Raffaele Scientific Institute, Milan, Italy
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31
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Luigetti M, Bolino A, Scarlino S, Sabatelli M. A novel homozygous mutation in the MTMR2 gene in two siblings with 'hypermyelinating neuropathy'. J Peripher Nerv Syst 2014; 18:192-4. [PMID: 23781969 DOI: 10.1111/jns5.12019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Guo L, Moon C, Zheng Y, Ratner N. Cdc42 regulates Schwann cell radial sorting and myelin sheath folding through NF2/merlin-dependent and independent signaling. Glia 2013; 61:1906-21. [PMID: 24014231 DOI: 10.1002/glia.22567] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 07/02/2013] [Accepted: 08/02/2013] [Indexed: 12/20/2022]
Abstract
The Rho family GTPase Cdc42 has been implicated in developmental Schwann cell (SC) proliferation, providing sufficient SCs for radial sorting of axons preceding SC differentiation in the peripheral nervous system. We generated Cdc42 conditional knockout (Cdc42-CKO) mice and confirmed aberrant axon sorting in Cdc42-CKO nerves. In adult Cdc42-CKO nerves, blood vessels were enlarged, and mature Remak bundles containing small axons were absent. Abnormal infoldings and outfoldings of myelin sheaths developed in Cdc42-CKO nerves, mimicking pathological features of Charcot-Marie-Tooth (CMT) disease. The NF2/merlin tumor suppressor has been implicated up- and down-stream of Cdc42. In Cdc42-CKO;NF2-del double mutant mice, radial sorting defects seen in Cdc42-CKO nerves were rescued, while changes in myelin sheaths in Cdc42-CKO nerves were not. Phosphorylation of Focal adhesion kinase (FAK) and P-GSK3β, as well as expression of β-catenin were decreased in Cdc42-CKO nerves, and these changes were rescued by NF2/merlin mutation in Cdc42-CKO;NF2-del double mutant mice. Thus, Cdc42 regulates SC radial sorting in vivo through NF2/merlin dependent signaling pathways, while Cdc42 modulation of myelin sheath folding is NF2/merlin independent.
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Affiliation(s)
- Li Guo
- Division of Experimental Hematology and Cancer Biology, Department of Pediatrics, Cincinnati Children's Hospital University of Cincinnati, Cincinnati, Ohio
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33
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Arai H, Hayashi M, Hayasaka K, Kanda T, Tanabe Y. The first Japanese case of Charcot-Marie-Tooth disease type 4H with a novel FGD4 c.837-1G>A mutation. Neuromuscul Disord 2013; 23:652-5. [PMID: 23770104 DOI: 10.1016/j.nmd.2013.04.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 03/27/2013] [Accepted: 04/30/2013] [Indexed: 12/18/2022]
Abstract
Charcot-Marie-Tooth disease type 4H (CMT4H) is an autosomal recessive demyelinating neuropathy. It presents as infancy or early childhood-onset neuropathy associated with FGD4 mutations. Clinically it causes predominantly distal muscle weakness. On nerve biopsy examination, myelin outfoldings are seen. The previous case reports have been from regions bordering the Mediterranean, as well as a family from Northern Ireland. This paper presents the detailed clinical course of the first reported case of CMT4H in a Japanese woman. The patient showed mild weakness without scoliosis and a severe sensory disturbance; her functional impairment was less severe than the previously published cases. In addition, a novel homozygous FGD4 c.837-1G>A mutation was identified in this patient.
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Affiliation(s)
- Hidee Arai
- Department of Neurology, Chiba Children's Hospital, Chiba, Japan.
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34
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Tazir M, Bellatache M, Nouioua S, Vallat JM. Autosomal recessive Charcot-Marie-Tooth disease: from genes to phenotypes. J Peripher Nerv Syst 2013; 18:113-29. [DOI: 10.1111/jns5.12026] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/19/2013] [Accepted: 03/19/2013] [Indexed: 11/27/2022]
Affiliation(s)
- Meriem Tazir
- Service de Neurologie; University Hospital Mustapha Bacha; Alger Algeria
- Laboratoire de NeuroSciences; Université d'Alger 1; Alger Algeria
| | - Mounia Bellatache
- Service de Neurologie; University Hospital Mustapha Bacha; Alger Algeria
- Laboratoire de NeuroSciences; Université d'Alger 1; Alger Algeria
| | - Sonia Nouioua
- Service de Neurologie; University Hospital Mustapha Bacha; Alger Algeria
- Laboratoire de NeuroSciences; Université d'Alger 1; Alger Algeria
| | - Jean-Michel Vallat
- Centre de Référence ⟨Neuropathies Périphériques Rares⟩, Service et Laboratoire de Neurologie; University Hospital; Limoges France
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Zhu H, Guariglia S, Yu RYL, Li W, Brancho D, Peinado H, Lyden D, Salzer J, Bennett C, Chow CW. Mutation of SIMPLE in Charcot-Marie-Tooth 1C alters production of exosomes. Mol Biol Cell 2013; 24:1619-37, S1-3. [PMID: 23576546 PMCID: PMC3667717 DOI: 10.1091/mbc.e12-07-0544] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mutations in the protein SIMPLE account for the rare autosomal-dominant demyelination in type 1C CMT patients (CMT1C). SIMPLE plays a role in the production of exosomes. Dysregulated endosomal trafficking and changes in exosome-mediated intercellular communications might account for CMT1C molecular pathogenesis. Charcot–Marie–Tooth (CMT) disease is an inherited neurological disorder. Mutations in the small integral membrane protein of the lysosome/late endosome (SIMPLE) account for the rare autosomal-dominant demyelination in CMT1C patients. Understanding the molecular basis of CMT1C pathogenesis is impeded, in part, by perplexity about the role of SIMPLE, which is expressed in multiple cell types. Here we show that SIMPLE resides within the intraluminal vesicles of multivesicular bodies (MVBs) and inside exosomes, which are nanovesicles secreted extracellularly. Targeting of SIMPLE to exosomes is modulated by positive and negative regulatory motifs. We also find that expression of SIMPLE increases the number of exosomes and secretion of exosome proteins. We engineer a point mutation on the SIMPLE allele and generate a physiological mouse model that expresses CMT1C-mutated SIMPLE at the endogenous level. We find that CMT1C mouse primary embryonic fibroblasts show decreased number of exosomes and reduced secretion of exosome proteins, in part due to improper formation of MVBs. CMT1C patient B cells and CMT1C mouse primary Schwann cells show similar defects. Together the data indicate that SIMPLE regulates the production of exosomes by modulating the formation of MVBs. Dysregulated endosomal trafficking and changes in the landscape of exosome-mediated intercellular communications may place an overwhelming burden on the nervous system and account for CMT1C molecular pathogenesis.
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Affiliation(s)
- Hong Zhu
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY 10461, USA
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36
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Ng AA, Logan AM, Schmidt EJ, Robinson FL. The CMT4B disease-causing phosphatases Mtmr2 and Mtmr13 localize to the Schwann cell cytoplasm and endomembrane compartments, where they depend upon each other to achieve wild-type levels of protein expression. Hum Mol Genet 2013; 22:1493-506. [PMID: 23297362 DOI: 10.1093/hmg/dds562] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The demyelinating peripheral neuropathy Charcot-Marie-Tooth type 4B (CMT4B) is characterized by axonal degeneration and myelin outfoldings. CMT4B results from mutations in either myotubularin-related protein 2 (MTMR2; CMT4B1) or MTMR13 (CMT4B2), phosphoinositide (PI) 3-phosphatases that dephosphorylate phosphatidylinositol 3-phosphate (PtdIns3P) and PtdIns(3,5)P2, lipids which regulate endo-lysosomal membrane traffic. The catalytically active MTMR2 and catalytically inactive MTMR13 physically associate, although the significance of this association is not well understood. Here we show that Mtmr13 loss leads to axonal degeneration in sciatic nerves of older mice. In addition, CMT4B2-like myelin outfoldings are present in Mtmr13(-/-) nerves at postnatal day 3. Thus, Mtmr13(-/-) mice show both the initial dysmyelination and later degenerative pathology of CMT4B2. Given the key role of PI 3-kinase-Akt signaling in myelination, we investigated the state of the pathway in nerves of CMT4B models. We found that Akt activation is unaltered in Mtmr13(-/-) and Mtmr2(-/-) mice. Mtmr2 and Mtmr13 are found within the Schwann cell cytoplasm, where the proteins are partially localized to punctate compartments, suggesting that Mtmr2-Mtmr13 may dephosphorylate their substrates on specific intracellular compartments. Mtmr2-Mtmr13 substrates play essential roles in endo-lysosomal membrane traffic. However, endosomes and lysosomes of Mtmr13(-/-) and Mtmr2(-/-) Schwann cells are morphologically indistinguishable from those of controls, indicating that loss of these proteins does not cause wholesale dysregulation of the endo-lysosomal system. Notably, Mtmr2 and Mtmr13 depend upon each other to achieve wild-type levels of protein expression. Mtmr2 stabilizes Mtmr13 on membranes, indicating that the Mtmr13 pseudophosphatase is regulated by its catalytically active binding partner.
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Affiliation(s)
- Aubree A Ng
- The Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA
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37
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Shy ME. Lessons from London. J Neurol Neurosurg Psychiatry 2012; 83:767-8. [PMID: 22696588 PMCID: PMC3721145 DOI: 10.1136/jnnp-2012-302858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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38
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Tronchère H, Bolino A, Laporte J, Payrastre B. Myotubularins and associated neuromuscular diseases. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/clp.12.7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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39
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Bucci C, Bakke O, Progida C. Charcot-Marie-Tooth disease and intracellular traffic. Prog Neurobiol 2012; 99:191-225. [PMID: 22465036 PMCID: PMC3514635 DOI: 10.1016/j.pneurobio.2012.03.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 12/23/2011] [Accepted: 03/13/2012] [Indexed: 12/23/2022]
Abstract
Mutations of genes whose primary function is the regulation of membrane traffic are increasingly being identified as the underlying causes of various important human disorders. Intriguingly, mutations in ubiquitously expressed membrane traffic genes often lead to cell type- or organ-specific disorders. This is particularly true for neuronal diseases, identifying the nervous system as the most sensitive tissue to alterations of membrane traffic. Charcot-Marie-Tooth (CMT) disease is one of the most common inherited peripheral neuropathies. It is also known as hereditary motor and sensory neuropathy (HMSN), which comprises a group of disorders specifically affecting peripheral nerves. This peripheral neuropathy, highly heterogeneous both clinically and genetically, is characterized by a slowly progressive degeneration of the muscle of the foot, lower leg, hand and forearm, accompanied by sensory loss in the toes, fingers and limbs. More than 30 genes have been identified as targets of mutations that cause CMT neuropathy. A number of these genes encode proteins directly or indirectly involved in the regulation of intracellular traffic. Indeed, the list of genes linked to CMT disease includes genes important for vesicle formation, phosphoinositide metabolism, lysosomal degradation, mitochondrial fission and fusion, and also genes encoding endosomal and cytoskeletal proteins. This review focuses on the link between intracellular transport and CMT disease, highlighting the molecular mechanisms that underlie the different forms of this peripheral neuropathy and discussing the pathophysiological impact of membrane transport genetic defects as well as possible future ways to counteract these defects.
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Affiliation(s)
- Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via Provinciale Monteroni, 73100 Lecce, Italy.
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40
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Hnia K, Kretz C, Amoasii L, Böhm J, Liu X, Messaddeq N, Qu CK, Laporte J. Primary T-tubule and autophagy defects in the phosphoinositide phosphatase Jumpy/MTMR14 knockout mice muscle. Adv Biol Regul 2012; 52:98-107. [PMID: 21930146 DOI: 10.1016/j.advenzreg.2011.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 09/06/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Karim Hnia
- Department of Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), 1, rue Laurent Fries, BP10142, 67404 Illkirch, France
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41
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Xhabija B, Taylor GS, Fujibayashi A, Sekiguchi K, Vacratsis PO. Receptor mediated endocytosis 8 is a novel PI(3)P binding protein regulated by myotubularin-related 2. FEBS Lett 2011; 585:1722-8. [PMID: 21510942 DOI: 10.1016/j.febslet.2011.04.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 03/17/2011] [Accepted: 04/07/2011] [Indexed: 01/19/2023]
Abstract
Myotubularin related protein 2 (MTMR2) is a member of the myotubularin family of phosphoinositide lipid phosphatases. Although MTMR2 dephosphorylates the phosphoinositides PI(3)P and PI(3,5)P2, the phosphoinositide binding proteins that are regulated by MTMR2 are poorly characterized. In this study, phosphoinositide affinity chromatography coupled to mass spectrometry identified receptor mediated endocytosis 8 (RME-8) as a novel PI(3)P binding protein. RME-8 co-localized with the PI(3)P marker DsRed-FYVE, while the N-terminal region of RME-8 is required for PI(3)P and PI(3,5)P(2) binding in vitro. Depletion of PI(3)P by MTMR2 S58A or wortmannin treatment attenuated RME-8 endosomal localization and co-localization with EGFR on early endosomes. Our results suggest a model in which the localization of RME-8 to endosomal compartments is spatially mediated by PI(3)P binding and temporally regulated by MTMR2 activity.
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Affiliation(s)
- Besa Xhabija
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
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Razidlo GL, Katafiasz D, Taylor GS. Myotubularin regulates Akt-dependent survival signaling via phosphatidylinositol 3-phosphate. J Biol Chem 2011; 286:20005-19. [PMID: 21478156 DOI: 10.1074/jbc.m110.197749] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myotubularin is a 3-phosphoinositide phosphatase that is mutated in X-linked myotubular myopathy, a severe neonatal disorder in which skeletal muscle development and/or regeneration is impaired. In this report we provide evidence that siRNA-mediated silencing of myotubularin expression markedly inhibits growth factor-stimulated Akt phosphorylation, leading to activation of caspase-dependent pro-apoptotic signaling in HeLa cells and primary human skeletal muscle myotubes. Myotubularin silencing also inhibits Akt-dependent signaling through the mammalian target of rapamycin complex 1 as assessed by p70 S6-kinase and 4E-BP1 phosphorylation. Similarly, phosphorylation of FoxO transcription factors is also significantly reduced in myotubularin-deficient cells. Our data further suggest that inhibition of Akt activation and downstream survival signaling in myotubularin-deficient cells is caused by accumulation of the MTMR substrate lipid phosphatidylinositol 3-phosphate generated from the type II phosphatidylinositol 3-kinase PIK3C2B. Our findings are significant because they suggest that myotubularin regulates Akt activation via a cellular pool of phosphatidylinositol 3-phosphate that is distinct from that generated by the type III phosphatidylinositol 3-kinase hVps34. Because impaired Akt signaling has been tightly linked to skeletal muscle atrophy, we hypothesize that loss of Akt-dependent growth/survival cues due to impaired myotubularin function may be a critical factor underlying the severe skeletal muscle atrophy characteristic of muscle fibers in patients with X-linked myotubular myopathy.
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Affiliation(s)
- Gina L Razidlo
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5870, USA
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The phosphoinositide 3-phosphatase MTMR2 interacts with PSD-95 and maintains excitatory synapses by modulating endosomal traffic. J Neurosci 2010; 30:5508-18. [PMID: 20410104 DOI: 10.1523/jneurosci.4283-09.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
MTMR2 is a 3-phosphatase specific for the phosphoinositides PI(3)P and PI(3,5)P(2), which are mainly present on endosomes. Mutations in the MTMR2 gene in Schwann cells lead to a severe demyelinating peripheral neuropathy known as Charcot-Marie-Tooth disease type 4B1. MTMR2 expression is also detected in peripheral and central neurons, but neural functions of MTMR2 remain unclear. Here, we report that MTMR2 is localized to excitatory synapses of central neurons via direct interaction with PSD-95, a postsynaptic scaffolding protein abundant at excitatory synapses. Knockdown of MTMR2 in cultured neurons markedly reduces excitatory synapse density and function. This effect is rescued by wild-type MTMR2 but not by a mutant MTMR2 lacking PSD-95 binding or 3-phosphatase activity. MTMR2 knockdown leads to a decrease in the intensity of EEA1-positive early endosomes in dendrites but increases the intensity in the cell body region. Moreover, MTMR2 suppression promotes endocytosis, but not recycling, of the GluR2 subunit of AMPA receptors, which is an endosomal cargo. In addition, colocalization of internalized GluR2 with Lamp1-positive late endosomes/lysosomes is enhanced in the cell body area but not in dendrites. These results suggest that PSD-95-interacting MTMR2 contributes to the maintenance of excitatory synapses by inhibiting excessive endosome formation and destructive endosomal traffic to lysosomes.
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Dowling JJ, Low SE, Busta AS, Feldman EL. Zebrafish MTMR14 is required for excitation-contraction coupling, developmental motor function and the regulation of autophagy. Hum Mol Genet 2010; 19:2668-81. [PMID: 20400459 DOI: 10.1093/hmg/ddq153] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Myotubularins are a family of dual-specificity phosphatases that act to modify phosphoinositides and regulate membrane traffic. Mutations in several myotubularins are associated with human disease. Sequence changes in MTM1 and MTMR14 (also known as Jumpy) have been detected in patients with a severe skeletal myopathy called centronuclear myopathy. MTM1 has been characterized in vitro and in several model systems, while the function of MTMR14 and its specific role in muscle development and disease is much less well understood. We have previously reported that knockdown of zebrafish MTM1 results in significantly impaired motor function and severe histopathologic changes in skeletal muscle that are characteristic of human centronuclear myopathy. In the current study, we examine zebrafish MTMR14 using gene dosage manipulation. As with MTM1 knockdown, morpholino-mediated knockdown of MTMR14 results in morphologic abnormalities, a developmental motor phenotype characterized by diminished spontaneous contractions and abnormal escape response, and impaired excitation-contraction coupling. In contrast to MTM1 knockdown, however, muscle ultrastructure is unaffected. Double knockdown of both MTM1 and MTMR14 significantly impairs motor function and alters skeletal muscle ultrastructure. The combined effect of reducing levels of both MTMR14 and MTM1 is significantly more severe than either knockdown alone, an effect which is likely mediated, at least in part, by increased autophagy. In all, our results suggest that MTMR14 is required for motor function and, in combination with MTM1, is required for myocyte homeostasis and normal embryonic development.
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Affiliation(s)
- J J Dowling
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA.
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45
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Falasca M, Maffucci T. Rethinking phosphatidylinositol 3-monophosphate. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1795-803. [PMID: 19852987 DOI: 10.1016/j.bbamcr.2009.10.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/13/2009] [Revised: 10/06/2009] [Accepted: 10/13/2009] [Indexed: 11/27/2022]
Abstract
A generally accepted view considers phosphatidylinositol 3-monophosphate (PtdIns3P) as a lipid confined to the endosomal compartment where it regulates trafficking pathways and is produced constitutively and exclusively by class III phosphoinositide 3-kinase (PI3K). Recent evidence suggests that this phosphoinositide has a more complex role as a second messenger involved in different physiological and pathological events and that specific intracellular localization of kinases and/or phosphatases is critical for PtdIns3P synthesis and PtdIns3P-dependent intracellular functions. Here, we review the current knowledge of the regulation and function of PtdIns3P and discuss how the view of PtdIns3P changed in the last few years.
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Affiliation(s)
- Marco Falasca
- Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Blizard Institute of Cell and Molecular Science, Centre for Diabetes, Inositide Signalling Group, 4 Newark Street, London E1 2AT, UK.
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Abstract
How membrane biosynthesis and homeostasis is achieved in myelinating glia is mostly unknown. We previously reported that loss of myotubularin-related protein 2 (MTMR2) provokes autosomal recessive demyelinating Charcot-Marie-Tooth type 4B1 neuropathy, characterized by excessive redundant myelin, also known as myelin outfoldings. We generated a Mtmr2-null mouse that models the human neuropathy. We also found that, in Schwann cells, Mtmr2 interacts with Discs large 1 (Dlg1), a scaffold involved in polarized trafficking and membrane addition, whose localization in Mtmr2-null nerves is altered. We here report that, in Schwann cells, Dlg1 also interacts with kinesin 13B (kif13B) and Sec8, which are involved in vesicle transport and membrane tethering in polarized cells, respectively. Taking advantage of the Mtmr2-null mouse as a model of impaired membrane formation, we provide here the first evidence for a machinery that titrates membrane formation during myelination. We established Schwann cell/DRG neuron cocultures from Mtmr2-null mice, in which myelin outfoldings were reproduced and almost completely rescued by Mtmr2 replacement. By exploiting this in vitro model, we propose a mechanism whereby kif13B kinesin transports Dlg1 to sites of membrane remodeling where it coordinates a homeostatic control of myelination. The interaction of Dlg1 with the Sec8 exocyst component promotes membrane addition, whereas with Mtmr2, negatively regulates membrane formation. Myelin outfoldings thus arise as a consequence of the loss of negative control on the amount of membrane, which is produced during myelination.
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Feltri ML, Suter U, Relvas JB. The function of RhoGTPases in axon ensheathment and myelination. Glia 2009; 56:1508-1517. [PMID: 18803320 DOI: 10.1002/glia.20752] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
RhoGTPases are molecular switches that integrate extracellular signals to perform diverse cellular responses. This ability relies on the network of proteins regulating RhoGTPases activity and localization, and on the interaction of RhoGTPases with many different cellular effectors. Myelination is an ideal place for RhoGTPases regulation, as it is the result of fine orchestration of many stimuli from at least two cell types. Recent work has revealed that RhoGTPases are required for Schwann cells to sort, ensheath, and myelinate axons. Here, we will review these recent advances showing the critical roles for RhoGTPases in various aspects of Schwann development and myelination, including the recent discovery of their involvement in Charcot-Marie-Tooth disease. Comparison with potential roles of RhoGTPases in central nervous system myelination will be drawn.
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Affiliation(s)
- M Laura Feltri
- DIBIT, San Raffaele Scientific Institute, Milano, Italy.
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48
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Abstract
The past 15 years have witnessed the identification of more than 25 genes responsible for inherited neuropathies in humans, many associated with primary alterations of the myelin sheath. A remarkable body of work in patients, as well as animal and cellular models, has defined the clinical and molecular genetics of these illnesses and shed light on how mutations in associated genes produce the heterogeneity of dysmyelinating and demyelinating phenotypes. Here, we review selected recent developments from work on the molecular mechanisms of these disorders and their implications for treatment strategies.
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Affiliation(s)
- Steven S Scherer
- The University of Pennsylvania Medical School, Philadelphia, Pennsylvania
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49
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Loss of the inactive myotubularin-related phosphatase Mtmr13 leads to a Charcot-Marie-Tooth 4B2-like peripheral neuropathy in mice. Proc Natl Acad Sci U S A 2008; 105:4916-21. [PMID: 18349142 DOI: 10.1073/pnas.0800742105] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Charcot-Marie-Tooth disease type 4B (CMT4B) is a severe, demyelinating peripheral neuropathy characterized by slowed nerve conduction velocity, axon loss, and distinctive myelin outfolding and infolding. CMT4B is caused by recessive mutations in either myotubularin-related protein 2 (MTMR2; CMT4B1) or MTMR13 (CMT4B2). Myotubularins are phosphoinositide (PI) 3-phosphatases that dephosphorylate phosphatidylinositol 3-phosphate (PtdIns3P) and PtdIns(3,5)P(2), two phosphoinositides that regulate endosomal-lysosomal membrane traffic. Interestingly, nearly half of the metazoan myotubularins are predicted to be catalytically inactive. Both active and inactive myotubularins have essential functions in mammals and in Caenorhabditis elegans. MTMR2 and MTMR13 are active and inactive PI 3-phosphatases, respectively, and the two proteins have been shown to directly associate, although the functional significance of this association is not well understood. To establish a mouse model of CMT4B2, we disrupted the Mtmr13 gene. Mtmr13-deficient mice develop a peripheral neuropathy characterized by reduced nerve conduction velocity and myelin outfoldings and infoldings. Dysmyelination is evident in Mtmr13-deficient nerves at 14 days and worsens throughout life. Thus, loss of Mtmr13 in mice leads to a peripheral neuropathy with many of the key features of CMT4B2. Although myelin outfoldings and infoldings occur most frequently at the paranode, our morphological analyses indicate that the ultrastructure of the node of Ranvier and paranode is intact in Mtmr13-deficient nerve fibers. We also found that Mtmr2 levels are decreased by approximately 50% in Mtmr13-deficient sciatic nerves, suggesting a mode of Mtmr2 regulation. Mtmr13-deficient mice will be an essential tool for studying how the loss of MTMR13 leads to CMT4B2.
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