1
|
Rebelo AP, Abad C, Dohrn MF, Li JJ, Tieu E, Medina J, Yanick C, Huang J, Zotter B, Young JI, Saporta M, Scherer SS, Walz K, Zuchner S. Sord deficient rats develop a motor-predominant peripheral neuropathy unveiling novel pathophysiological insights. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.05.570001. [PMID: 38106042 PMCID: PMC10723320 DOI: 10.1101/2023.12.05.570001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Biallelic SORD mutations cause one of the most frequent forms of recessive hereditary neuropathy, estimated to affect approximately 10,000 patients in North America and Europe alone. Pathogenic SORD loss-of-function changes in the encoded enzyme sorbitol dehydrogenase result in abnormally high sorbitol levels in cells and serum. How sorbitol accumulation leads to peripheral neuropathy remains to be elucidated. A reproducible animal model for SORD neuropathy is essential to illuminate the pathogenesis of SORD deficiency and for preclinical studies of potential therapies. Therefore, we have generated a Sord knockout (KO), Sord -/- , Sprague Dawley rat, to model the human disease and to investigate the pathophysiology underlying SORD deficiency. We have characterized the phenotype in these rats with a battery of behavioral tests as well as biochemical, physiological, and comprehensive histological examinations. Sord -/- rats had remarkably increased levels of sorbitol in serum, cerebral spinal fluid (CSF), and peripheral nerve. Moreover, serum from Sord -/- rats contained significantly increased levels of neurofilament light chain, NfL, an established biomarker for axonal degeneration. Motor performance significantly declined in Sord -/- animals starting at ∼7 months of age. Gait analysis evaluated with video motion tracking confirmed abnormal gait patterns in the hindlimbs. Motor nerve conduction velocities of the tibial nerves were slowed. Light and electron microscopy of the peripheral nervous system revealed degenerating myelinated axons, de- and remyelinated axons, and a likely pathognomonic finding - enlarged "ballooned" myelin sheaths. These findings mainly affected myelinated motor axons; myelinated sensory axons were largely spared. In summary, Sord -/- rats develop a motor-predominant neuropathy that closely resembles the human phenotype. Our studies revealed novel significant aspects of SORD deficiency, and this model will lead to an improved understanding of the pathophysiology and the therapeutic options for SORD neuropathy.
Collapse
|
2
|
Zhou Y, Miles JR, Tavori H, Lin M, Khoshbouei H, Borchelt DR, Bazick H, Landreth GE, Lee S, Fazio S, Notterpek L. PMP22 Regulates Cholesterol Trafficking and ABCA1-Mediated Cholesterol Efflux. J Neurosci 2019; 39:5404-5418. [PMID: 31061090 PMCID: PMC6607759 DOI: 10.1523/jneurosci.2942-18.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 04/22/2019] [Accepted: 04/26/2019] [Indexed: 12/21/2022] Open
Abstract
The absence of functional peripheral myelin protein 22 (PMP22) is associated with shortened lifespan in rodents and severe peripheral nerve myelin abnormalities in several species including humans. Schwann cells and nerves from PMP22 knock-out (KO) mice show deranged cholesterol distribution and aberrant lipid raft morphology, supporting an unrecognized role for PMP22 in cellular lipid metabolism. To examine the mechanisms underlying these abnormalities, we studied Schwann cells and nerves from male and female PMP22 KO mice. Whole-cell current-clamp recordings in cultured Schwann cells revealed increased membrane capacitance and decreased membrane resistance in the absence of PMP22, which was consistent with a reduction in membrane cholesterol. Nerves from PMP22-deficient mice contained abnormal lipid droplets, with both mRNA and protein levels of apolipoprotein E (apoE) and ATP-binding cassette transporter A1 (ABCA1) being highly upregulated. Despite the upregulation of ABCA1 and apoE, the absence of PMP22 resulted in reduced localization of the transporter to the cell membrane and diminished secretion of apoE. The absence of PMP22 also impaired ABCA1-mediated cholesterol efflux capacity. In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant. In wild-type samples, double immunolabeling identified overlapping distribution of PMP22 and ABCA1 at the Schwann cell plasma membrane and the two proteins were coimmunoprecipitated from Schwann cell and nerve lysates. Together, these results reveal a novel role for PMP22 in regulating lipid metabolism and cholesterol trafficking through functional interaction with the cholesterol efflux regulatory protein ABCA1.SIGNIFICANCE STATEMENT Understanding the subcellular events that underlie abnormal myelin formation in hereditary neuropathies is critical for advancing therapy development. Peripheral myelin protein 22 (PMP22) is an essential peripheral myelin protein because its genetic abnormalities account for ∼80% of hereditary neuropathies. Here, we demonstrate that in the absence of PMP22, the cellular and electrophysiological properties of the Schwann cells' plasma membrane are altered and cholesterol trafficking and lipid homeostasis are perturbed. The molecular mechanisms for these abnormalities involve a functional interplay among PMP22, cholesterol, apolipoprotein E, and the major cholesterol-efflux transporter protein ATP-binding cassette transporter A1 (ABCA1). These findings establish a critical role for PMP22 in the maintenance of cholesterol homeostasis in Schwann cells.
Collapse
Affiliation(s)
| | - Joshua R Miles
- Department of Medicine
- Department of Physiology and Pharmacology, Knight Cardiovascular Institute, Center of Preventive Cardiology, Oregon Health & Science University, Portland, Oregon 27332, and
| | - Hagai Tavori
- Department of Medicine
- Department of Physiology and Pharmacology, Knight Cardiovascular Institute, Center of Preventive Cardiology, Oregon Health & Science University, Portland, Oregon 27332, and
| | | | | | | | | | - Gary E Landreth
- Department of Neurosciences, Indiana University, Indianapolis, Indiana 46202
| | | | - Sergio Fazio
- Department of Medicine
- Department of Physiology and Pharmacology, Knight Cardiovascular Institute, Center of Preventive Cardiology, Oregon Health & Science University, Portland, Oregon 27332, and
| | - Lucia Notterpek
- Department of Neuroscience,
- Department of Neurology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610
| |
Collapse
|
3
|
Falk DJ, Galatas T, Todd AG, Soto EP, Harris AB, Notterpek L. Locomotor and skeletal muscle abnormalities in trembler J neuropathic mice. Muscle Nerve 2017; 57:664-671. [PMID: 29023846 DOI: 10.1002/mus.25987] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2017] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Patients with hereditary peripheral neuropathies exhibit characteristic deformities of the hands and feet and have difficulty ambulating. To examine to what extent neuropathic animals recapitulate these deficits, we studied trembler J (TrJ) mice, which model early-onset demyelinating neuropathy. METHODS A cohort of 4-month-old female wild type and neuropathic mice were evaluated for locomotor measurements, neuromuscular function, and skeletal muscle proteolysis and morphometry. RESULTS Utilizing the DigiGait imaging system, we identified pronounced alterations in forepaw and hindpaw angles and a decrease in hindpaw area on the treadmill in neuropathic rodents. Torque production by the tibialis anterior (TA) muscle was significantly weakened and was paralleled by a decrease in myofiber cross-sectional area and an increase in muscle tissue proteolysis. DISCUSSION Our findings in TrJ mice reflect the phenotypic presentation of the human neuropathy in which patients exhibit weakness of the TA muscle resulting in foot drop and locomotor abnormalities. Muscle Nerve 57: 664-671, 2018.
Collapse
Affiliation(s)
- Darin J Falk
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, 1149 Newell Drive, Box 100244 Gainesville, Florida, 32610-0244, USA.,Department of Pediatrics, College of Medicine, University of Florida, Gainesville, Florida, 32610-0244, USA
| | - Tori Galatas
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, 1149 Newell Drive, Box 100244 Gainesville, Florida, 32610-0244, USA
| | - Adrian G Todd
- Department of Pediatrics, College of Medicine, University of Florida, Gainesville, Florida, 32610-0244, USA
| | - Elliott P Soto
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, 1149 Newell Drive, Box 100244 Gainesville, Florida, 32610-0244, USA
| | - Andrew B Harris
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, 1149 Newell Drive, Box 100244 Gainesville, Florida, 32610-0244, USA
| | - Lucia Notterpek
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, 1149 Newell Drive, Box 100244 Gainesville, Florida, 32610-0244, USA.,Department of Neurology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| |
Collapse
|
4
|
Nicks J, Lee S, Harris A, Falk DJ, Todd AG, Arredondo K, Dunn WA, Notterpek L. Rapamycin improves peripheral nerve myelination while it fails to benefit neuromuscular performance in neuropathic mice. Neurobiol Dis 2014; 70:224-36. [PMID: 25014022 DOI: 10.1016/j.nbd.2014.06.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/19/2014] [Accepted: 06/30/2014] [Indexed: 11/16/2022] Open
Abstract
Charcot--Marie-Tooth disease type 1A (CMT1A) is a hereditary peripheral neuropathy characterized by progressive demyelination and distal muscle weakness. Abnormal expression of peripheral myelin protein 22 (PMP22) has been linked to CMT1A and is modeled by Trembler J (TrJ) mice, which carry the same leucine to proline substitution in PMP22 as affected pedigrees. Pharmacologic modulation of autophagy by rapamycin in neuron-Schwann cell explant cultures from neuropathic mice reduced PMP22 aggregate formation and improved myelination. Here we asked whether rapamycin administration by food supplementation, or intraperitoneal injection, could alleviate the neuropathic phenotype of affected mice and improve neuromuscular performance. Cohorts of male and female wild type (Wt) and TrJ mice were assigned to placebo or rapamycin treatment starting at 2 or 4months of age and tested monthly on the rotarod. While neither long-term feeding (8 or 10months) on rapamycin-enriched diet, or short-term injection (2months) of rapamycin improved locomotor performance of the neuropathic mice, both regimen benefited peripheral nerve myelination. Together, these results indicate that while treatment with rapamycin benefits the myelination capacity of neuropathic Schwann cells, this intervention does not improve neuromuscular function. The observed outcome might be the result of the differential response of nerve and skeletal muscle tissue to rapamycin.
Collapse
Affiliation(s)
- Jessica Nicks
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Sooyeon Lee
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Andrew Harris
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Darin J Falk
- Department of Pediatrics, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Adrian G Todd
- Department of Pediatrics, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Karla Arredondo
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - William A Dunn
- Department of Anatomy and Cell Biology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Lucia Notterpek
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Department of Neurology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Department of Anatomy and Cell Biology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
| |
Collapse
|
5
|
Faroni A, Smith R, Procacci P, Castelnovo L, Puccianti E, Reid A, Magnaghi V, Verkhratsky A. Purinergic signaling mediated by P2X7receptors controls myelination in sciatic nerves. J Neurosci Res 2014; 92:1259-69. [DOI: 10.1002/jnr.23417] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/07/2014] [Accepted: 04/24/2014] [Indexed: 12/31/2022]
Affiliation(s)
- A. Faroni
- Blond McIndoe Laboratories; Institute of Inflammation and Repair, University of Manchester; Manchester United Kingdom
- Faculty of Life Sciences; University of Manchester; Manchester United Kingdom
| | - R.J.P. Smith
- Blond McIndoe Laboratories; Institute of Inflammation and Repair, University of Manchester; Manchester United Kingdom
- Faculty of Life Sciences; University of Manchester; Manchester United Kingdom
| | - P. Procacci
- Dipartimento di Scienze Biomediche per la Salute; Università degli Studi di Milano; Milan Italy
| | - L.F. Castelnovo
- Dipartimento di Scienze Farmacologiche e Biomolecolari; Università degli Studi di Milano; Milan Italy
| | - E. Puccianti
- Dipartimento di Scienze Biomediche per la Salute; Università degli Studi di Milano; Milan Italy
| | - A.J. Reid
- Blond McIndoe Laboratories; Institute of Inflammation and Repair, University of Manchester; Manchester United Kingdom
| | - V. Magnaghi
- Dipartimento di Scienze Farmacologiche e Biomolecolari; Università degli Studi di Milano; Milan Italy
| | - A. Verkhratsky
- Faculty of Life Sciences; University of Manchester; Manchester United Kingdom
| |
Collapse
|
6
|
Bouhy D, Timmerman V. Animal models and therapeutic prospects for Charcot-Marie-Tooth disease. Ann Neurol 2013; 74:391-6. [PMID: 23913540 DOI: 10.1002/ana.23987] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 07/04/2013] [Accepted: 07/29/2013] [Indexed: 12/14/2022]
Abstract
Charcot-Marie-Tooth (CMT) neuropathies are inherited neuromuscular disorders caused by a length-dependent neurodegeneration of peripheral nerves. More than 900 mutations in 60 different genes are causative of the neuropathy. Despite significant progress in therapeutic strategies, the disease remains incurable. The increasing number of genes linked to the disease, and their considerable clinical and genetic heterogeneity render the development of these strategies particularly challenging. In this context, cellular and animals models provide powerful tools. Efficient motor and sensory tests have been developed to assess the behavioral phenotype in transgenic animal models (rodent and fly). When these models reproduce a phenotype comparable to CMT, they allow therapeutic approaches and the discovery of modifiers and biomarkers. In this review, we describe the most convincing transgenic rodent and fly models of CMT and how they can lead to clinical trial. We also discuss the challenges that the research, the clinic, and the pharmaceutical industry will face in developing efficient and accessible treatment for CMT patients.
Collapse
Affiliation(s)
- Delphine Bouhy
- Peripheral Neuropathy Group, Department of Molecular Genetics, Flanders Interuniversity Institute for Biotechnology, Institute Born Bunge, University of Antwerp, Antwerp, Belgium
| | | |
Collapse
|
7
|
Fledrich R, Stassart RM, Sereda MW. Murine therapeutic models for Charcot-Marie-Tooth (CMT) disease. Br Med Bull 2012; 102:89-113. [PMID: 22551516 DOI: 10.1093/bmb/lds010] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION OR BACKGROUND Charcot-Marie-Tooth (CMT) disease represents a broad group of inherited motor and sensory neuropathies which can originate from various genetic aberrations, e.g. mutations, deletions and duplications. SOURCES OF DATA We performed a literature review on murine animal models of CMT disease with regard to experimental therapeutic approaches. Hereby, we focussed on the demyelinating subforms of CMT (CMT1). PubMed items were CMT, animal model, demyelination and therapy. AREAS OF AGREEMENT Patients affected by CMT suffer from slowly progressive, distally pronounced muscle atrophy caused by an axonal loss. The disease severity is highly variable and impairments may result in wheelchair boundness. No therapy is available yet. AREAS OF CONTROVERSY Numerous rodent models for the various CMT subtypes are available today. The selection of the correct animal model for the specific CMT subtype provides an important prerequisite for the successful translation of experimental findings in patients. GROWING POINTS Despite more than 20 years of remarkable progress in CMT research, the disease is still left untreatable. There is a growing number of experimental therapeutic strategies that may be translated into future clinical trials in patients with CMT. AREAS TIMELY FOR DEVELOPING RESEARCH The slow disease progression and insensitive outcome measures hamper clinical therapy trials in CMT. Biomarkers may provide powerful tools to monitor therapeutic efficacy. Recently, we have shown that transcriptional profiling can be utilized to assess and predict the disease severity in a transgenic rat model and in affected humans.
Collapse
Affiliation(s)
- Robert Fledrich
- Research Group 'Molecular and Translational Neurology', Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
| | | | | |
Collapse
|
8
|
Saporta MA, Grskovic M, Dimos JT. Induced pluripotent stem cells in the study of neurological diseases. Stem Cell Res Ther 2011; 2:37. [PMID: 21936964 PMCID: PMC3308034 DOI: 10.1186/scrt78] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Five years after their initial derivation from mouse somatic cells, induced pluripotent stem (iPS) cells are an important tool for the study of neurological diseases. By offering an unlimited source of patient-specific disease-relevant neuronal and glial cells, iPS cell-based disease models hold enormous promise for identification of disease mechanisms, discovery of molecular targets and development of phenotypic screens for drug discovery. The present review focuses on the recent advancements in modeling neurological disorders, including the demonstration of disease-specific phenotypes in iPS cell-derived neurons generated from patients with spinal muscular atrophy, familial dysautonomia, Rett syndrome, schizophrenia and Parkinson disease. The ability of this approach to detect treatment effects from known therapeutic compounds has also been demonstrated, providing proof of principle for the use of iPS cell-derived cells in drug discovery.
Collapse
Affiliation(s)
- Mario A Saporta
- iPierian, Inc,, 951 Gateway Blvd, South San Francisco, CA 94080, USA.
| | | | | |
Collapse
|
9
|
Filali M, Dequen F, Lalonde R, Julien JP. Sensorimotor and cognitive function of a NEFL(P22S) mutant model of Charcot-Marie-Tooth disease type 2E. Behav Brain Res 2010; 219:175-80. [PMID: 21168446 DOI: 10.1016/j.bbr.2010.12.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 12/08/2010] [Accepted: 12/10/2010] [Indexed: 11/15/2022]
Abstract
Charcot-Marie-Tooth (CMT) disease is the most frequently encountered hereditary disease causing sensorimotor neuropathies and slowly progressive muscle weakness and atrophy. The P22S mutation of the NEFL gene encoding the light polypeptide neurofilament (NFL) is associated with CMT. To understand more clearly the pathogenesis of sensorimotor dysfunction in CMT, we generated transgenic mice with the NEFL(P22S) mutation under the tet-off tetracycline regulated system with involvement of the Thy1 neuron-specific promoter. NEFL(P22S) transgenic mice exhibited extended duration of the hindlimb clasping response and gait anomalies, as well as sensorimotor deficits in stationary beam and suspended bar tests. In addition, the NEFL(P22S) mice were deficient in the reversal phase of left-right discrimination learning in a water maze. This model mimics some aspects of human CMT pathology and provides an opportunity of ameliorating CMT symptoms with experimental therapies.
Collapse
Affiliation(s)
- Mohammed Filali
- CHUL Research Center and Department of Molecular Medicine, Laval University, 2705 Laurier boul., Québec G1V 4G2, Canada.
| | | | | | | |
Collapse
|
10
|
Genomic and clinical characteristics of microduplications in chromosome 17. Am J Med Genet A 2010; 152A:1101-10. [DOI: 10.1002/ajmg.a.33248] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
11
|
Characterization of the MAL2-positive compartment in oligodendrocytes. Exp Cell Res 2009; 315:3453-65. [DOI: 10.1016/j.yexcr.2009.08.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 07/21/2009] [Accepted: 08/02/2009] [Indexed: 01/13/2023]
|
12
|
Lennon PA, Boerkoel CF, Plunkett K, Soukam S, Cheung SW, Patel A. A novel 8.5 MB dup(1)(p34.1p34.3) characterized by FISH in a child presenting with congenital heart defect and dysmorphic features. Am J Med Genet A 2006; 140A:1864-70. [PMID: 16892326 DOI: 10.1002/ajmg.a.31392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Chromosome duplications involving 1p are rarely reported but are apparently associated with short survival as well as congenital malformations and impaired development. Several of these have had congenital heart defects, although too few patients have been reported with similar breakpoints to characterize a syndrome. We present a girl with a novel interstitial duplication in the short arm of chromosome 1 [46,XX,dup(1)(p34.1p34.3)]. She presented with congenital heart defects at 1 month and by 1 year of age manifested delayed acquisition of motor milestones and subsequently of language milestones. By breakpoint-mapping using FISH analysis, we determined that her 1p duplication spans 8.5 megabases. Her 1p duplication is the smallest reported to date to contain 1p34 in patients with congenital heart defect due to abnormalities of heart looping during development. Thus, her 8.5 MB duplication provides a target region to search for a potentially dosage-sensitive gene(s) causing abnormal heart looping when duplicated. Two patients have been reported with duplication including 1p34 but without congenital heart defect, and their duplications span all but the distal approximately 2 MB segment duplicated in our patient. Thus, within our patient's 8.5 MB target region for a dosage sensitive gene leading to looping abnormalities (and thereby congenital heart defect), the distal 2 MB region might well be the region to begin the search.
Collapse
Affiliation(s)
- P A Lennon
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77021, USA
| | | | | | | | | | | |
Collapse
|
13
|
Wang Ip C, Kroner A, Fischer S, Berghoff M, Kobsar I, Mäurer M, Martini R. Role of immune cells in animal models for inherited peripheral neuropathies. Neuromolecular Med 2006; 8:175-90. [PMID: 16775375 DOI: 10.1385/nmm:8:1-2:175] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 11/10/2005] [Accepted: 11/15/2005] [Indexed: 12/20/2022]
Abstract
Mice expressing half of the normal dose of protein zero (P0+/- mice) or completely deficient gap-junction protein connexin 32 -/- mice mimic demyelinating forms of inherited neuropathies, such as Charcot-Marie-Tooth (CMT) neuropathies type 1B and CMT type 1X, respectively. In both models, an almost normal myelin formation is observed during the first months of life, followed by a slowly progressing demyelinating neuropathy. In both models, there is a substantial increase of CD8+ T-lymphocytes and macrophages within the demyelinating nerves. Recently, this has also been observed in mice mildly overexpressing human peripheral myelin protein 22 kD mimicking the most common form of CMT, CMT type 1A. In all demyelinating models, the macrophages show close contacts with intact myelin sheaths or demyelinated axons, suggesting an active role of these cells in myelin degeneration. Additionally, fibroblast-like cells contact macrophages, suggesting a functional role of fibroblast-like cells in macrophage activation. By cross-breeding P0+/- and gap-junction protein connexin 32-/- mice with immunodeficient recombination activating gene-1-deficient mutants, a substantial alleviation of the demyelinating phenotype was observed. Similarly, cross-breeding of P0+/- mice with mutants with a defect in macrophage activation led to an alleviated phenotype as well. These findings demonstrate that the immune system is involved in the pathogenesis of demyelinating neuropathies. In contrast, in P0-/- mice, which display a compromised myelin compaction and axonal loss from onset, immune cells appear to have a neuroprotective effect because cross-breeding with recombination activating gene-1 mutants leads to an aggravation of axonopathic changes. In the present review, we discuss the influence of the immune system on inherited de- and dysmyelination regarding disease mechanisms and possible clinical implications.
Collapse
Affiliation(s)
- Chi Wang Ip
- Department of Neurology, Developmental Neurobiology, University of Wuerzburg, Josef-Schneider-Str. 11, D-97080 Wuerzburg, Germany
| | | | | | | | | | | | | |
Collapse
|
14
|
Diers A, Kaczinski M, Grohmann K, Hübner C, Stoltenburg-Didinger G. The ultrastructure of peripheral nerve, motor end-plate and skeletal muscle in patients suffering from spinal muscular atrophy with respiratory distress type 1 (SMARD1). Acta Neuropathol 2005; 110:289-97. [PMID: 16025284 DOI: 10.1007/s00401-005-1056-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 06/06/2005] [Accepted: 06/06/2005] [Indexed: 11/26/2022]
Abstract
Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is genetically and clinically distinct from classic spinal muscular atrophy (SMA1). It results from mutations in the gene encoding immunoglobulin mu-binding protein 2 (IGHMBP2) on chromosome 11q13. Patients develop distally pronounced muscular weakness and early involvement of the diaphragm, resulting in respiratory failure. Sensory and autonomic nerves are also affected at later stages of the disease. We investigated peripheral nerves, skeletal muscles and neuromuscular junctions (NMJ) ultrastructurally in five unrelated patients and three siblings with genetically confirmed SMARD1. In mixed motor and sensory nerves we detected Wallerian degeneration and axonal atrophy similar to the ultrastructural findings described in SMA1. Isolated axonal atrophy was evident in purely sensory nerves. All investigated NMJ of patients with SMARD1 were dysmorphic and lacked a terminal axon. Moreover, we also observed characteristics of neuropathies, such as abnormalities in myelination, that have not been described in spinal muscular atrophies so far. Based on these findings we conclude that impairment of IGHMBP2 function leads to axonal degeneration, abnormal myelin formation, and motor end-plate degeneration.
Collapse
MESH Headings
- Axons/pathology
- Axons/ultrastructure
- DNA-Binding Proteins/genetics
- Female
- Humans
- Infant
- Infant, Newborn
- Male
- Microscopy, Electron, Transmission
- Motor Neurons/pathology
- Motor Neurons/ultrastructure
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Muscle, Skeletal/ultrastructure
- Muscular Atrophy, Spinal/complications
- Muscular Atrophy, Spinal/pathology
- Muscular Atrophy, Spinal/physiopathology
- Mutation/genetics
- Nerve Fibers, Myelinated/pathology
- Nerve Fibers, Myelinated/ultrastructure
- Neuromuscular Junction/pathology
- Neuromuscular Junction/physiopathology
- Neuromuscular Junction/ultrastructure
- Neurons, Afferent/pathology
- Neurons, Afferent/ultrastructure
- Peripheral Nerves/pathology
- Peripheral Nerves/physiopathology
- Peripheral Nerves/ultrastructure
- Respiratory Distress Syndrome, Newborn/etiology
- Respiratory Distress Syndrome, Newborn/pathology
- Respiratory Distress Syndrome, Newborn/physiopathology
- Transcription Factors/genetics
- Wallerian Degeneration/pathology
- Wallerian Degeneration/physiopathology
Collapse
Affiliation(s)
- Alexander Diers
- Department of Paediatric Neurology, Charité, Medical Faculty, Humboldt University, Augustenburger Platz 1, 13353 Berlin, Germany.
| | | | | | | | | |
Collapse
|
15
|
Kobsar I, Hasenpusch-Theil K, Wessig C, Müller HW, Martini R. Evidence for macrophage-mediated myelin disruption in an animal model for Charcot-Marie-Tooth neuropathy type 1A. J Neurosci Res 2005; 81:857-64. [PMID: 16041800 DOI: 10.1002/jnr.20601] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Charcot-Marie-Tooth neuropathy type 1A (CMT 1 A) is the most common inherited neuropathy in humans and is mostly caused by a 1.5-Mb tandem duplication of chromosome 17 comprising the gene for the peripheral myelin protein 22-kDa (PMP 22). Although there are numerous studies on the functional role of PMP 22, the mechanisms of myelin degeneration under PMP 22-overexpression conditions have not yet been fully understood. We have shown previously that in mouse mutants hetero- or homozygously deficient for two other myelin components, P0 and C x 32, respectively, immune cells contribute to the demyelinating neuropathy. To test this possibility for PMP 22 overexpression, we investigated a putative mouse model for CMT 1 A, i.e., the mouse strain C 6 1 mildly overexpressing human PMP 22 in peripheral nerves. Electron microscopic and electrophysiologic investigations revealed that this mouse strain develops pathologic features similar to those found in CMT 1 A patients. A novel finding, however, was the upregulation of CD8- and F4/80-positive lymphocytes and macrophages, respectively, in peripheral nerves. The observation that macrophages enter endoneurial tubes of the mutants and obviously phagocytose morphologically normal myelin strongly suggests that the myelin degeneration is mediated at least partially by these phagocytic cells. By gene array technology and quantitative RT-PCR of peripheral nerve homogenates from PMP 22 mutants, monocyte chemoattractant protein-1 (MCP-1; cc l2) could be identified as a putative factor to attract or activate macrophages that attack myelin sheaths in this model of CMT 1 A.
Collapse
Affiliation(s)
- Igor Kobsar
- Developmental Neurobiology, Department of Neurology, University of Würzburg, Würzburg, Germany
| | | | | | | | | |
Collapse
|
16
|
Atanasoski S, Scherer SS, Nave KA, Suter U. Proliferation of Schwann cells and regulation of cyclin D1 expression in an animal model of Charcot-Marie-Tooth disease type 1A. J Neurosci Res 2002; 67:443-9. [PMID: 11835311 DOI: 10.1002/jnr.10133] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Overexpression of PMP22 is responsible for the most common form of inherited neuropathy, Charcot-Marie-Tooth disease (CMT) type 1A. The PMP22-transgenic rat (CMT rat) is an animal model of CMT1A, and its peripheral nerves show the characteristic features of ongoing demyelination and remyelination that is also seen in CMT1A patients. Since Schwann cell proliferation is a prominent feature of peripheral nerves in inherited peripheral neuropathies, we examined proliferation and the expression of cyclin D1 in CMT rats. D-type cyclins are required for the initial steps in cell division and nuclear import is crucial for the function of cyclin D1 in promoting cell proliferation. Like normal myelinating Schwann cells in wild-type rats, remyelinating Schwann cells in CMT rats show perinuclear cyclin D1 expression. Schwann cells with nuclear cyclin D1 expression, as well as proliferating Schwann cells, were both associated with demyelinated axonal segments. Supernumerary onion bulb Schwann cells, however, do not express cyclin D1 and were not proliferating. Thus, cyclin D1 expression and its subcellular localization correlate directly with distinct physiological states of Schwann cells in this animal model of CMT1A.
Collapse
Affiliation(s)
- Suzana Atanasoski
- Institute of Cell Biology, Department of Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zurich, Switzerland
| | | | | | | |
Collapse
|
17
|
Abstract
In the central nervous system (CNS), the myelin sheath is synthesised by oligodendrocytes as a specialised subdomain of an extended plasma membrane, reminiscent of the segregated membrane domains of polarised cells. Myelination takes place within a relatively short period of time and oligodendrocytes must have adapted membrane sorting and transport mechanisms to achieve such a high rate of myelin synthesis and to maintain the unique organisation of the myelin membrane. In adult life, maintenance of the functional myelin sheath requires a carefully orchestrated balance of myelin synthesis and turnover. Imbalance in these processes may cause dys- or demyelination and disease. This review summarises what is currently known about myelin protein trafficking and mistrafficking in oligodendrocytes. We also present data demonstrating distinct transport pathways for myelin structural proteins and the expression of SNARE proteins in differentiating oligodendrocytes. Myelinating glial cells may well serve as a model system for studying general aspects of membrane trafficking and organisation of membrane domains.
Collapse
Affiliation(s)
- E M Krämer
- Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Str. 3, 37035 Göttingen, Germany.
| | | | | |
Collapse
|