scholarly journals Disruption of Mtmr2 produces CMT4B1-like neuropathy with myelin outfolding and impaired spermatogenesis

2004 ◽  
Vol 167 (4) ◽  
pp. 711-721 ◽  
Author(s):  
Alessandra Bolino ◽  
Annalisa Bolis ◽  
Stefano Carlo Previtali ◽  
Giorgia Dina ◽  
Simona Bussini ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Cell Polarity ◽  
Autosomal Recessive ◽  
Vesicle Transport ◽  
Physical Interaction ◽  
Demyelinating Neuropathy ◽  
Charcot Marie Tooth ◽  
Discs Large ◽  
Cellular Junctions

Mutations in MTMR2, the myotubularin-related 2 gene, cause autosomal recessive Charcot-Marie-Tooth (CMT) type 4B1, a demyelinating neuropathy with myelin outfolding and azoospermia. MTMR2 encodes a ubiquitously expressed phosphatase whose preferred substrate is phosphatidylinositol (3,5)-biphosphate, a regulator of membrane homeostasis and vesicle transport. We generated Mtmr2-null mice, which develop progressive neuropathy characterized by myelin outfolding and recurrent loops, predominantly at paranodal myelin, and depletion of spermatids and spermatocytes from the seminiferous epithelium, which leads to azoospermia. Disruption of Mtmr2 in Schwann cells reproduces the myelin abnormalities. We also identified a novel physical interaction in Schwann cells, between Mtmr2 and discs large 1 (Dlg1)/synapse-associated protein 97, a scaffolding molecule that is enriched at the node/paranode region. Dlg1 homologues have been located in several types of cellular junctions and play roles in cell polarity and membrane addition. We propose that Schwann cell–autonomous loss of Mtmr2–Dlg1 interaction dysregulates membrane homeostasis in the paranodal region, thereby producing outfolding and recurrent loops of myelin.

Charcot–Marie–Tooth type 4B demyelinating neuropathy: deciphering the role of MTMR phosphatases

2007 ◽  
Vol 9 (25) ◽  
pp. 1-16 ◽  
Author(s):  
Stefano C. Previtali ◽  
Angelo Quattrini ◽  
Alessandra Bolino
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Autosomal Recessive ◽  
Protein Tyrosine Phosphatases ◽  
Vesicular Trafficking ◽  
Demyelinating Neuropathy ◽  
Charcot Marie Tooth ◽  
Catalytically Active ◽  
Tooth Type

AbstractCharcot–Marie–Tooth type 4B (CMT4B) is a severe autosomal recessive neuropathy with demyelination and myelin outfoldings of the nerve. This disorder is genetically heterogeneous, but thus far, mutations in myotubularin-related 2 (MTMR2) and MTMR13 genes have been shown to underlie CMT4B1 and CMT4B2, respectively. MTMR2 and MTMR13 belong to a family of ubiquitously expressed proteins sharing homology with protein tyrosine phosphatases (PTPs). The MTMR family, which has 14 members in humans, comprises catalytically active proteins, such as MTMR2, and catalytically inactive proteins, such as MTMR13. Despite their homology with PTPs, catalytically active MTMR phosphatases dephosphorylate both PtdIns3P and PtdIns(3,5)P2 phosphoinositides. Thus, MTMR2 and MTMR13 may regulate vesicular trafficking in Schwann cells. Loss of these proteins could lead to uncontrolled folding of myelin and, ultimately, to CMT4B. In this review, we discuss recent findings on this interesting protein family with the main focus on MTMR2 and MTMR13 and their involvement in the biology of Schwann cell and CMT4B neuropathies.

scholarly journals Impaired NDRG1 functions in Schwann cells cause demyelinating neuropathy in a dog model of Charcot-Marie-Tooth type 4D

2021 ◽  
Vol 31 (1) ◽  
pp. 56-68
Author(s):  
Fredrik S. Skedsmo ◽  
Arild Espenes ◽  
Michael A. Tranulis ◽  
Kaspar Matiasek ◽  
Gjermund Gunnes ◽  
...  
Keyword(s):  
Schwann Cells ◽  
Demyelinating Neuropathy ◽  
Charcot Marie Tooth ◽  
Dog Model ◽  
Tooth Type

MicroRNAs as Biomarkers of Charcot-Marie-Tooth Disease Type 1A

Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000012266
Author(s):  
Hongge Wang ◽  
Matthew Davison ◽  
Kathryn Wang ◽  
Tai-he Xia ◽  
Katherine M. Call ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Motor Nerve ◽  
Disease Type ◽  
Class Iii ◽  
Protein Biomarkers ◽  
Charcot Marie Tooth ◽  
Charcot Marie Tooth Disease ◽  
Compound Muscle Action Potentials ◽  
Tooth Disease

Objective:To determine if microRNA’s (miR) are elevated in the plasma of individuals affected by the inherited peripheral neuropathy Charcot-Marie-Tooth Disease, type 1A (CMT1A), miR profiling was employed to compare control and CMT1A plasma.Methods:We performed a screen of CMT1A and control plasma samples to identify miRs that are elevated in CMT1A using next generation sequencing, followed by validation of selected miRs by quantitative PCR, and correlation with protein biomarkers and clinical data: Rash-modified CMT Examination and Neuropathy Scores (CMTES-R and CMTNS-R), ulnar compound muscle action potentials (CMAP), and motor nerve conduction velocities (MNCV).Results:After an initial pilot screen, a broader screen confirmed elevated levels of several muscle-associated miRNAs (miR1, -133a, -133b, and -206, known as myomiRs) along with a set of miRs that are highly expressed in Schwann cells of peripheral nerve. Comparison to other candidate biomarkers for CMT1A (e.g. Neurofilament L, NfL) measured on the same sample set shows a comparable elevation of several miRs (e.g. miR133a, -206, -223) and ability to discriminate cases from controls. NfL levels were most highly correlated with miR133a. In addition, the putative Schwann cell miRs (e.g. miR223, -199a, -328, -409, and -431) correlate with the recently described TMPRSS5 protein biomarker that is most highly expressed in Schwann cells and also elevated in CMT1A plasma.Conclusions:These studies identify a set of miRs that are candidate biomarkers for clinical trials in CMT1A. Some of the miRs may reflect Schwann cell processes that underlie the pathogenesis of the disease.Classification of Evidence:This study provides Class III evidence that a set of plasma miRs are elevated in patients with CMT1A.

scholarly journals Resetting translational homeostasis restores myelination in Charcot-Marie-Tooth disease type 1B mice

2013 ◽  
Vol 210 (4) ◽  
pp. 821-838 ◽  
Author(s):  
Maurizio D’Antonio ◽  
Nicolò Musner ◽  
Cristina Scapin ◽  
Daniela Ungaro ◽  
Ubaldo Del Carro ◽  
...  
Keyword(s):  
Schwann Cells ◽  
Therapeutic Strategy ◽  
Terminal Differentiation ◽  
Motor Deficit ◽  
Demyelinating Neuropathy ◽  
Charcot Marie Tooth ◽  
Charcot Marie Tooth Disease ◽  
Unfolded Protein ◽  
Protein Response ◽  
Tooth Disease

P0 glycoprotein is an abundant product of terminal differentiation in myelinating Schwann cells. The mutant P0S63del causes Charcot-Marie-Tooth 1B neuropathy in humans, and a very similar demyelinating neuropathy in transgenic mice. P0S63del is retained in the endoplasmic reticulum of Schwann cells, where it promotes unfolded protein stress and elicits an unfolded protein response (UPR) associated with translational attenuation. Ablation of Chop, a UPR mediator, from S63del mice completely rescues their motor deficit and reduces active demyelination by half. Here, we show that Gadd34 is a detrimental effector of CHOP that reactivates translation too aggressively in myelinating Schwann cells. Genetic or pharmacological limitation of Gadd34 function moderates translational reactivation, improves myelination in S63del nerves, and reduces accumulation of P0S63del in the ER. Resetting translational homeostasis may provide a therapeutic strategy in tissues impaired by misfolded proteins that are synthesized during terminal differentiation.

Human Neurofibromas in Co-Culture with Mouse Neurons

1982 ◽  
Vol 40 ◽  
pp. 194-195
Author(s):  
R.L. Martuza ◽  
T. Liszczak ◽  
A. Okun ◽  
T-Y Wang
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Genetic Disorder ◽  
Cranial Nerves ◽  
Sympathetic Nerves ◽  
Acoustic Neuromas ◽  
Spinal Roots ◽  
Neural Crest Origin ◽  
Multiple Abnormalities ◽  
Other Neoplasms

Neurofibromatosis (NF) is an autosomal dominant genetic disorder with a prevalence of 1/3,000 births. The NF mutation causes multiple abnormalities of various cells of neural crest origin. Schwann cell tumors (neurofibromas, acoustic neuromas) are the most common feature of neurofibromatosis although meningiomas, gliomas, and other neoplasms may be seen. The schwann cell tumors commonly develop from the schwann cells associated with sensory or sympathetic nerves or their ganglia. Schwann cell tumors on ventral spinal roots or motor cranial nerves are much less common. Since the sensory neuron membrane is known to contain a mitogenic factor for schwann cells, we have postulated that neurofibromatosis may be due to an abnormal interaction between the nerve and the schwann cell and that this interaction may be hormonally modulated. To test this possibility a system has been developed in which an enriched schwannoma cell culture can be obtained and co-cultured with pure neurons.

scholarly journals Transposon Mutagenesis-Guided CRISPR/Cas9 Screening Strongly Implicates Dysregulation of Hippo/YAP Signaling in Malignant Peripheral Nerve Sheath Tumor Development

Cancers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1584
Author(s):  
Germán L. Vélez-Reyes ◽  
Nicholas Koes ◽  
Ji Hae Ryu ◽  
Gabriel Kaufmann ◽  
Mariah Berner ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Schwann Cell ◽  
Peripheral Nerve ◽  
Cell Line ◽  
Schwann Cells ◽  
Tumor Suppressor Genes ◽  
Tumor Formation ◽  
Loss Of Function ◽  
Suppressor Genes ◽  
Nerve Sheath

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive, genomically complex, have soft tissue sarcomas, and are derived from the Schwann cell lineage. Patients with neurofibromatosis type 1 syndrome (NF1), an autosomal dominant tumor predisposition syndrome, are at a high risk for MPNSTs, which usually develop from pre-existing benign Schwann cell tumors called plexiform neurofibromas. NF1 is characterized by loss-of-function mutations in the NF1 gene, which encode neurofibromin, a Ras GTPase activating protein (GAP) and negative regulator of RasGTP-dependent signaling. In addition to bi-allelic loss of NF1, other known tumor suppressor genes include TP53, CDKN2A, SUZ12, and EED, all of which are often inactivated in the process of MPNST growth. A sleeping beauty (SB) transposon-based genetic screen for high-grade Schwann cell tumors in mice, and comparative genomics, implicated Wnt/β-catenin, PI3K-AKT-mTOR, and other pathways in MPNST development and progression. We endeavored to more systematically test genes and pathways implicated by our SB screen in mice, i.e., in a human immortalized Schwann cell-based model and a human MPNST cell line, using CRISPR/Cas9 technology. We individually induced loss-of-function mutations in 103 tumor suppressor genes (TSG) and oncogene candidates. We assessed anchorage-independent growth, transwell migration, and for a subset of genes, tumor formation in vivo. When tested in a loss-of-function fashion, about 60% of all TSG candidates resulted in the transformation of immortalized human Schwann cells, whereas 30% of oncogene candidates resulted in growth arrest in a MPNST cell line. Individual loss-of-function mutations in the TAOK1, GDI2, NF1, and APC genes resulted in transformation of immortalized human Schwann cells and tumor formation in a xenograft model. Moreover, the loss of all four of these genes resulted in activation of Hippo/Yes Activated Protein (YAP) signaling. By combining SB transposon mutagenesis and CRISPR/Cas9 screening, we established a useful pipeline for the validation of MPNST pathways and genes. Our results suggest that the functional genetic landscape of human MPNST is complex and implicate the Hippo/YAP pathway in the transformation of neurofibromas. It is thus imperative to functionally validate individual cancer genes and pathways using human cell-based models, to determinate their role in different stages of MPNST development, growth, and/or metastasis.

scholarly journals Mice carrying an analogous heterozygous dynamin 2 K562E mutation that causes neuropathy in humans develop predominant characteristics of a primary myopathy

2020 ◽  
Vol 29 (8) ◽  
pp. 1253-1273
Author(s):  
Jorge A Pereira ◽  
Joanne Gerber ◽  
Monica Ghidinelli ◽  
Daniel Gerber ◽  
Luigi Tortola ◽  
...  
Keyword(s):  
Mouse Model ◽  
Treatment Strategies ◽  
Underlying Disease ◽  
Potential Treatment ◽  
Type B ◽  
Disease Mechanism ◽  
Demyelinating Neuropathy ◽  
Charcot Marie Tooth ◽  
Dynamin 2

Abstract Some mutations affecting dynamin 2 (DNM2) can cause dominantly inherited Charcot–Marie–Tooth (CMT) neuropathy. Here, we describe the analysis of mice carrying the DNM2 K562E mutation which has been associated with dominant-intermediate CMT type B (CMTDIB). Contrary to our expectations, heterozygous DNM2 K562E mutant mice did not develop definitive signs of an axonal or demyelinating neuropathy. Rather, we found a primary myopathy-like phenotype in these mice. A likely interpretation of these results is that the lack of a neuropathy in this mouse model has allowed the unmasking of a primary myopathy due to the DNM2 K562E mutation which might be overshadowed by the neuropathy in humans. Consequently, we hypothesize that a primary myopathy may also contribute to the disease mechanism in some CMTDIB patients. We propose that these findings should be considered in the evaluation of patients, the determination of the underlying disease processes and the development of tailored potential treatment strategies.

scholarly journals Interleukin-4 Regulates the Expression of CD209 and Subsequent Uptake of Mycobacterium leprae by Schwann Cells in Human Leprosy

2010 ◽  
Vol 78 (11) ◽  
pp. 4634-4643 ◽  
Author(s):  
Rosane M. B. Teles ◽  
Stephan R. Krutzik ◽  
Maria T. Ochoa ◽  
Rosane B. Oliveira ◽  
Euzenir N. Sarno ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Peripheral Nerve ◽  
Schwann Cells ◽  
Primary Cultures ◽  
Mycobacterium Leprae ◽  
Microbial Pathogens ◽  
Interleukin 4 ◽  
Common Mechanism ◽  
Specific Cell

ABSTRACT The ability of microbial pathogens to target specific cell types is a key aspect of the pathogenesis of infectious disease. Mycobacterium leprae, by infecting Schwann cells, contributes to nerve injury in patients with leprosy. Here, we investigated mechanisms of host-pathogen interaction in the peripheral nerve lesions of leprosy. We found that the expression of the C-type lectin, CD209, known to be expressed on tissue macrophages and to mediate the uptake of M. leprae, was present on Schwann cells, colocalizing with the Schwann cell marker, CNPase (2′,3′-cyclic nucleotide 3′-phosphodiesterase), along with the M. leprae antigen PGL-1 in the peripheral nerve biopsy specimens. In vitro, human CD209-positive Schwann cells, both from primary cultures and a long-term line, have a higher binding of M. leprae compared to CD209-negative Schwann cells. Interleukin-4, known to be expressed in skin lesions from multibacillary patients, increased CD209 expression on human Schwann cells and subsequent Schwann cell binding to M. leprae, whereas Th1 cytokines did not induce CD209 expression on these cells. Therefore, the regulated expression of CD209 represents a common mechanism by which Schwann cells and macrophages bind and take up M. leprae, contributing to the pathogenesis of leprosy.

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