Publications by authors named "Elior Peles"

93 Publications

Neuronal deletion of Wwox, associated with WOREE syndrome, causes epilepsy and myelin defects.

Brain 2021 Apr 29. Epub 2021 Apr 29.

The Concern Foundation Laboratories, The Lautenberg Center for Immunology and Cancer Research, Immunology and Cancer Research-IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, Israel.

WOREE syndrome caused by human germline biallelic mutations in WWOX is a neurodevelopmental disorder characterized by intractable epilepsy, severe developmental delay, ataxia and premature death at the age of 2-4 years. The underlying mechanisms of WWOX actions are poorly understood. In the current study, we show that specific neuronal deletion of murine Wwox produces phenotypes typical of the Wwox-null mutation leading to brain hyperexcitability, intractable epilepsy, ataxia and postnatal lethality. A significant decrease in transcript levels of genes involved in myelination was observed in mouse cortex and hippocampus. Wwox-mutant mice exhibited reduced maturation of oligodendrocytes, reduced myelinated axons and impaired axonal conductivity. Brain hyperexcitability and hypomyelination were also revealed in human brain organoids with a WWOX deletion. These findings provide cellular and molecular evidence for myelination defects and hyperexcitability in the WOREE syndrome linked to neuronal function of WWOX.
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http://dx.doi.org/10.1093/brain/awab174DOI Listing
April 2021

A CADM3 variant causes Charcot-Marie-Tooth disease with marked upper limb involvement.

Brain 2021 05;144(4):1197-1213

Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA.

The CADM family of proteins consists of four neuronal specific adhesion molecules (CADM1, CADM2, CADM3 and CADM4) that mediate the direct contact and interaction between axons and glia. In the peripheral nerve, axon-Schwann cell interaction is essential for the structural organization of myelinated fibres and is primarily mediated by the binding of CADM3, expressed in axons, to CADM4, expressed by myelinating Schwann cells. We have identified-by whole exome sequencing-three unrelated families, including one de novo patient, with axonal Charcot-Marie-Tooth disease (CMT2) sharing the same private variant in CADM3, Tyr172Cys. This variant is absent in 230 000 control chromosomes from gnomAD and predicted to be pathogenic. Most CADM3 patients share a similar phenotype consisting of autosomal dominant CMT2 with marked upper limb involvement. High resolution mass spectrometry analysis detected a newly created disulphide bond in the mutant CADM3 potentially modifying the native protein conformation. Our data support a retention of the mutant protein in the endoplasmic reticulum and reduced cell surface expression in vitro. Stochastic optical reconstruction microscopy imaging revealed decreased co-localization of the mutant with CADM4 at intercellular contact sites. Mice carrying the corresponding human mutation (Cadm3Y170C) showed reduced expression of the mutant protein in axons. Cadm3Y170C mice showed normal nerve conduction and myelin morphology, but exhibited abnormal axonal organization, including abnormal distribution of Kv1.2 channels and Caspr along myelinated axons. Our findings indicate the involvement of abnormal axon-glia interaction as a disease-causing mechanism in CMT patients with CADM3 mutations.
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http://dx.doi.org/10.1093/brain/awab019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8105037PMC
May 2021

TDP-43 maximizes nerve conduction velocity by repressing a cryptic exon for paranodal junction assembly in Schwann cells.

Elife 2021 Mar 10;10. Epub 2021 Mar 10.

Department of Neurology, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States.

TDP-43 is extensively studied in neurons in physiological and pathological contexts. However, emerging evidence indicates that glial cells are also reliant on TDP-43 function. We demonstrate that deletion of TDP-43 in Schwann cells results in a dramatic delay in peripheral nerve conduction causing significant motor deficits in mice, which is directly attributed to the absence of paranodal axoglial junctions. By contrast, paranodes in the central nervous system are unaltered in oligodendrocytes lacking TDP-43. Mechanistically, TDP-43 binds directly to mRNA, encoding the cell adhesion molecule essential for paranode assembly and maintenance. Loss of TDP-43 triggers the retention of a previously unidentified cryptic exon, which targets mRNA for nonsense-mediated decay. Thus, TDP-43 is required for neurofascin expression, proper assembly and maintenance of paranodes, and rapid saltatory conduction. Our findings provide a framework and mechanism for how Schwann cell-autonomous dysfunction in nerve conduction is directly caused by TDP-43 loss-of-function.
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http://dx.doi.org/10.7554/eLife.64456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7946431PMC
March 2021

Differential Contribution of Cadm1-Cadm3 Cell Adhesion Molecules to Peripheral Myelinated Axons.

J Neurosci 2021 02 4;41(7):1393-1400. Epub 2021 Jan 4.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel

Cell adhesion proteins of the Cadm (SynCAM/Necl) family regulate myelination and the organization of myelinated axons. In the peripheral nervous system (PNS), intercellular contact between Schwann cells and their underlying axons is believed to be mediated by binding of glial Cadm4 to axonal Cadm3 or Cadm2. Nevertheless, given that distinct neurons express different combinations of the Cadm proteins, the identity of the functional axonal ligand for Cadm4 remains to be determined. Here, we took a genetic approach to compare the phenotype of null mice, which exhibit abnormal distribution of Caspr and Kv1 potassium channels, with mice lacking different combinations of - genes. We show that in contrast to mice lacking the single , , or genes, genetic ablation of all three phenocopies the abnormalities detected in the absence of Cadm4. Similar defects were observed in double mutant mice lacking Cadm3 and Cadm2 (i.e., ) or Cadm3 and Cadm1 (i.e., ), but not in mice lacking Cadm1 and Cadm2 (i.e., ). Furthermore, axonal organization abnormalities were also detected in null mice that were heterozygous for the two other axonal Cadms. Our results identify Cadm3 as the main axonal ligand for glial Cadm4, and reveal that its absence could be compensated by the combined action of Cadm2 and Cadm1. Myelination by Schwann cells enables fast conduction of action potentials along motor and sensory axons. In these nerves, Schwann cell-axon contact is mediated by cell adhesion molecules of the Cadm family. Cadm4 in Schwann cells regulates axonal ensheathment and myelin wrapping, as well as the organization of the axonal membrane, but the identity of its axonal ligands is not clear. Here, we reveal that Cadm mediated axon-glia interactions depend on a hierarchical adhesion code that involves multiple family members. Our results provide important insights into the molecular mechanisms of axon-glia communication, and the function of Cadm proteins in PNS myelin.
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http://dx.doi.org/10.1523/JNEUROSCI.2736-20.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7896006PMC
February 2021

Mechanisms of node of Ranvier assembly.

Nat Rev Neurosci 2021 01 25;22(1):7-20. Epub 2020 Nov 25.

Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel.

The nodes of Ranvier have clustered Na and K channels necessary for rapid and efficient axonal action potential conduction. However, detailed mechanisms of channel clustering have only recently been identified: they include two independent axon-glia interactions that converge on distinct axonal cytoskeletons. Here, we discuss how glial cell adhesion molecules and the extracellular matrix molecules that bind them assemble combinations of ankyrins, spectrins and other cytoskeletal scaffolding proteins, which cluster ion channels. We present a detailed molecular model, incorporating these overlapping mechanisms, to explain how the nodes of Ranvier are assembled in both the peripheral and central nervous systems.
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http://dx.doi.org/10.1038/s41583-020-00406-8DOI Listing
January 2021

Schwann-cell-derived CMTM6 restricts radial axonal growth.

Nat Commun 2020 10 7;11(1):5044. Epub 2020 Oct 7.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel.

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http://dx.doi.org/10.1038/s41467-020-18886-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7541498PMC
October 2020

N-Wasp Regulates Oligodendrocyte Myelination.

J Neurosci 2020 08 29;40(32):6103-6111. Epub 2020 Jun 29.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel

Oligodendrocyte myelination depends on actin cytoskeleton rearrangement. Neural Wiskott-Aldrich syndrome protein(N-Wasp) is an actin nucleation factor that promotes polymerization of branched actin filaments. N-Wasp activity is essential for myelin membrane wrapping by Schwann cells, but its role in oligodendrocytes and CNS myelination remains unknown. Here we report that oligodendrocytes-specific deletion of in mice of both sexes resulted in hypomyelination (i.e., reduced number of myelinated axons and thinner myelin profiles), as well as substantial focal hypermyelination reflected by the formation of remarkably long myelin outfolds. These myelin outfolds surrounded unmyelinated axons, neuronal cell bodies, and other myelin profiles. The latter configuration resulted in pseudo-multimyelin profiles that were often associated with axonal detachment and degeneration throughout the CNS, including in the optic nerve, corpus callosum, and the spinal cord. Furthermore, developmental analysis revealed that myelin abnormalities were already observed during the onset of myelination, suggesting that they are formed by aberrant and misguided elongation of the oligodendrocyte inner lip membrane. Our results demonstrate that N-Wasp is required for the formation of normal myelin in the CNS. They also reveal that N-Wasp plays a distinct role in oligodendrocytes compared with Schwann cells, highlighting a difference in the regulation of actin dynamics during CNS and PNS myelination. Myelin is critical for the normal function of the nervous system by facilitating fast conduction of action potentials. During the process of myelination in the CNS, oligodendrocytes undergo extensive morphological changes that involve cellular process extension and retraction, axonal ensheathment, and myelin membrane wrapping. Here we present evidence that N-Wasp, a protein regulating actin filament assembly through Arp2/3 complex-dependent actin nucleation, plays a critical role in CNS myelination, and its absence leads to several myelin abnormalities. Our data provide an important step into the understanding of the molecular mechanisms underlying CNS myelination.
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http://dx.doi.org/10.1523/JNEUROSCI.0912-20.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406274PMC
August 2020

Accumulation of Neurofascin at Nodes of Ranvier Is Regulated by a Paranodal Switch.

J Neurosci 2020 07 17;40(30):5709-5723. Epub 2020 Jun 17.

Neuroscience Institute and Departments of Neuroscience and Physiology and

The paranodal junctions flank mature nodes of Ranvier and provide a barrier between ion channels at the nodes and juxtaparanodes. These junctions also promote node assembly and maintenance by mechanisms that are poorly understood. Here, we examine their role in the accumulation of NF186, a key adhesion molecule of PNS and CNS nodes. We previously showed that NF186 is initially targeted/accumulates via its ectodomain to forming PNS (hemi)nodes by diffusion trapping, whereas it is later targeted to mature nodes by a transport-dependent mechanism mediated by its cytoplasmic segment. To address the role of the paranodes in this switch, we compared accumulation of NF186 ectodomain and cytoplasmic domain constructs in WT versus paranode defective (i.e., Caspr-null) mice. Both pathways are affected in the paranodal mutants. In the PNS of Caspr-null mice, diffusion trapping mediated by the NF186 ectodomain aberrantly persists into adulthood, whereas the cytoplasmic domain/transport-dependent targeting is impaired. In contrast, accumulation of NF186 at CNS nodes does not undergo a switch; it is predominantly targeted to both forming and mature CNS nodes via its cytoplasmic domain and requires intact paranodes. Fluorescence recovery after photobleaching analysis indicates that the paranodes provide a membrane diffusion barrier that normally precludes diffusion of NF186 to nodes. Linkage of paranodal proteins to the underlying cytoskeleton likely contributes to this diffusion barrier based on 4.1B and βII spectrin expression in Caspr-null mice. Together, these results implicate the paranodes as membrane diffusion barriers that regulate targeting to nodes and highlight differences in the assembly of PNS and CNS nodes. Nodes of Ranvier are essential for effective saltatory conduction along myelinated axons. A major question is how the various axonal proteins that comprise the multimeric nodal complex accumulate at this site. Here we examine how targeting of NF186, a key nodal adhesion molecule, is regulated by the flanking paranodal junctions. We show that the transition from diffusion-trapping to transport-dependent accumulation of NF186 requires the paranodal junctions. We also demonstrate that these junctions are a barrier to diffusion of axonal proteins into the node and highlight differences in PNS and CNS node assembly. These results provide new insights into the mechanism of node assembly and the pathophysiology of neurologic disorders in which impaired paranodal function contributes to clinical disability.
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http://dx.doi.org/10.1523/JNEUROSCI.0830-19.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380970PMC
July 2020

Precise Spatiotemporal Control of Nodal Na Channel Clustering by Bone Morphogenetic Protein-1/Tolloid-like Proteinases.

Neuron 2020 06 24;106(5):806-815.e6. Epub 2020 Mar 24.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address:

During development of the peripheral nervous system (PNS), Schwann-cell-secreted gliomedin induces the clustering of Na channels at the edges of each myelin segment to form nodes of Ranvier. Here we show that bone morphogenetic protein-1 (BMP1)/Tolloid (TLD)-like proteinases confine Na channel clustering to these sites by negatively regulating the activity of gliomedin. Eliminating the Bmp1/TLD cleavage site in gliomedin or treating myelinating cultures with a Bmp1/TLD inhibitor results in the formation of numerous ectopic Na channel clusters along axons that are devoid of myelin segments. Furthermore, genetic deletion of Bmp1 and Tll1 genes in mice using a Schwann-cell-specific Cre causes ectopic clustering of nodal proteins, premature formation of heminodes around early ensheathing Schwann cells, and altered nerve conduction during development. Our results demonstrate that by inactivating gliomedin, Bmp1/TLD functions as an additional regulatory mechanism to ensure the correct spatial and temporal assembly of PNS nodes of Ranvier.
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http://dx.doi.org/10.1016/j.neuron.2020.03.001DOI Listing
June 2020

The clustering of voltage-gated sodium channels in various excitable membranes.

Dev Neurobiol 2021 Jul 10;81(5):427-437. Epub 2020 Jan 10.

Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel.

In excitable membranes, the clustering of voltage-gated sodium channels (VGSC) serves to enhance excitability at critical sites. The two most profoundly studied sites of channel clustering are the axon initial segment, where action potentials are generated and the node of Ranvier, where action potentials propagate along myelinated axons. The clustering of VGSC is found, however, in other highly excitable sites such as axonal terminals, postsynaptic membranes of dendrites and muscle fibers, and pre-myelinated axons. In this review, different examples of axonal as well as non-axonal clustering of VGSC are discussed and the underlying mechanisms are compared. Whether the clustering of channels is intrinsically or extrinsically induced, it depends on the submembranous actin-based cytoskeleton that organizes these highly specialized membrane microdomains through specific adaptor proteins.
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http://dx.doi.org/10.1002/dneu.22728DOI Listing
July 2021

Two adhesive systems cooperatively regulate axon ensheathment and myelin growth in the CNS.

Nat Commun 2019 10 22;10(1):4794. Epub 2019 Oct 22.

Institute of Neuronal Cell Biology, Technical University Munich, Munich, Germany.

Central nervous system myelin is a multilayered membrane produced by oligodendrocytes to increase neural processing speed and efficiency, but the molecular mechanisms underlying axonal selection and myelin wrapping are unknown. Here, using combined morphological and molecular analyses in mice and zebrafish, we show that adhesion molecules of the paranodal and the internodal segment work synergistically using overlapping functions to regulate axonal interaction and myelin wrapping. In the absence of these adhesive systems, axonal recognition by myelin is impaired with myelin growing on top of previously myelinated fibers, around neuronal cell bodies and above nodes of Ranvier. In addition, myelin wrapping is disturbed with the leading edge moving away from the axon and in between previously formed layers. These data show how two adhesive systems function together to guide axonal ensheathment and myelin wrapping, and provide a mechanistic understanding of how the spatial organization of myelin is achieved.
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http://dx.doi.org/10.1038/s41467-019-12789-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6805957PMC
October 2019

Coordinated internodal and paranodal adhesion controls accurate myelination by oligodendrocytes.

J Cell Biol 2019 09 26;218(9):2887-2895. Epub 2019 Aug 26.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel

Oligodendrocyte-axon contact is mediated by several cell adhesion molecules (CAMs) that are positioned at distinct sites along the myelin unit, yet their role during myelination remains unclear. Cadm4 and its axonal receptors, Cadm2 and Cadm3, as well as myelin-associated glycoprotein (MAG), are enriched at the internodes below the compact myelin, whereas NF155, which binds the axonal Caspr/contactin complex, is located at the paranodal junction that is formed between the axon and the terminal loops of the myelin sheath. Here we report that Cadm4-, MAG-, and Caspr-mediated adhesion cooperate during myelin membrane ensheathment. Genetic deletion of either Cadm4 and MAG or Cadm4 and Caspr resulted in the formation of multimyelinated axons due to overgrowth of the myelin away from the axon and the forming paranodal junction. Consequently, these mice displayed paranodal loops either above or underneath compact myelin. Our results demonstrate that accurate placement of the myelin sheath by oligodendrocytes requires the coordinated action of internodal and paranodal CAMs.
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http://dx.doi.org/10.1083/jcb.201906099DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6719437PMC
September 2019

Axoglial Adhesion by Cadm4 Regulates CNS Myelination.

Neuron 2019 01 11;101(2):224-231.e5. Epub 2018 Dec 11.

Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address:

The initiation of axoglial contact is considered a prerequisite for myelination, yet the role cell adhesion molecules (CAMs) play in mediating such interactions remains unclear. To examine the function of axoglial CAMs, we tested whether enhanced CAM-mediated adhesion between OLs and neurons could affect myelination. Here we show that increased expression of a membrane-bound extracellular domain of Cadm4 (Cadm4dCT) in cultured oligodendrocytes results in the production of numerous axoglial contact sites that fail to elongate and generate mature myelin. Transgenic mice expressing Cadm4dCT were hypomyelinated and exhibit multiple myelin abnormalities, including myelination of neuronal somata. These abnormalities depend on specific neuron-glial interaction as they were not observed when these OLs were cultured alone, on nanofibers, or on neurons isolated from mice lacking the axonal receptors of Cadm4. Our results demonstrate that tightly regulated axon-glia adhesion is essential for proper myelin targeting and subsequent membrane wrapping and lateral extension.
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http://dx.doi.org/10.1016/j.neuron.2018.11.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6371057PMC
January 2019

Molecular pathogenesis of human CD59 deficiency.

Neurol Genet 2018 Dec 26;4(6):e280. Epub 2018 Oct 26.

Rheumatology Research Center (N.K., A.T., H.H., D.M.), Center of Rare Diseases, and Department of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem; The Weizmann Institute (Y.E.-E., E.P.), Rehovot, Israel; Systems Immunity Research Institute (B.P.M.), Cardiff University, Cardiff, Wales, UK; and Hebrew University (O.S.-F., D.M.), Jerusalem, Israel.

Objective: To characterize all 4 mutations described for CD59 congenital deficiency.

Methods: The 4 mutations, p.Cys64Tyr, p.Asp24Val, p.Asp24Valfs*, and p.Ala16Alafs*, were described in 13 individuals with CD59 malfunction. All 13 presented with recurrent Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy, recurrent strokes, and chronic hemolysis. Here, we track the molecular consequences of the 4 mutations and their effects on CD59 expression, localization, glycosylation, degradation, secretion, and function. Mutants were cloned and inserted into plasmids to analyze their expression, localization, and functionality.

Results: Immunolabeling of myc-tagged wild-type (WT) and mutant CD59 proteins revealed cell surface expression of p.Cys64Tyr and p.Asp24Val detected with the myc antibody, but no labeling by anti-CD59 antibodies. In contrast, frameshift mutants p.Asp24Valfs* and p.Ala16Alafs* were detected only intracellularly and did not reach the cell surface. Western blot analysis showed normal glycosylation but mutant-specific secretion patterns. All mutants significantly increased MAC-dependent cell lysis compared with WT. In contrast to CD59 knockout mice previously used to characterize phenotypic effects of CD59 perturbation, all 4 hCD59 mutations generate CD59 proteins that are expressed and may function intracellularly (4) or on the cell membrane (2). None of the 4 CD59 mutants are detected by known anti-CD59 antibodies, including the 2 variants present on the cell membrane. None of the 4 inhibits membrane attack complex (MAC) formation.

Conclusions: All 4 mutants generate nonfunctional CD59, 2 are expressed as cell surface proteins that may function in non-MAC-related interactions and 2 are expressed only intracellularly. Distinct secretion of soluble CD59 may have also a role in disease pathogenesis.
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http://dx.doi.org/10.1212/NXG.0000000000000280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6244018PMC
December 2018

Immune or Genetic-Mediated Disruption of CASPR2 Causes Pain Hypersensitivity Due to Enhanced Primary Afferent Excitability.

Neuron 2018 02 8;97(4):806-822.e10. Epub 2018 Feb 8.

Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.

Human autoantibodies to contactin-associated protein-like 2 (CASPR2) are often associated with neuropathic pain, and CASPR2 mutations have been linked to autism spectrum disorders, in which sensory dysfunction is increasingly recognized. Human CASPR2 autoantibodies, when injected into mice, were peripherally restricted and resulted in mechanical pain-related hypersensitivity in the absence of neural injury. We therefore investigated the mechanism by which CASPR2 modulates nociceptive function. Mice lacking CASPR2 (Cntnap2) demonstrated enhanced pain-related hypersensitivity to noxious mechanical stimuli, heat, and algogens. Both primary afferent excitability and subsequent nociceptive transmission within the dorsal horn were increased in Cntnap2 mice. Either immune or genetic-mediated ablation of CASPR2 enhanced the excitability of DRG neurons in a cell-autonomous fashion through regulation of Kv1 channel expression at the soma membrane. This is the first example of passive transfer of an autoimmune peripheral neuropathic pain disorder and demonstrates that CASPR2 has a key role in regulating cell-intrinsic dorsal root ganglion (DRG) neuron excitability.
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http://dx.doi.org/10.1016/j.neuron.2018.01.033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6011627PMC
February 2018

Loss of Cntnap2 Causes Axonal Excitability Deficits, Developmental Delay in Cortical Myelination, and Abnormal Stereotyped Motor Behavior.

Cereb Cortex 2019 02;29(2):586-597

Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan d'Alacant, Spain.

Contactin-associated protein-like 2 (Caspr2) is found at the nodes of Ranvier and has been associated with physiological properties of white matter conductivity. Genetic variation in CNTNAP2, the gene encoding Caspr2, has been linked to several neurodevelopmental conditions, yet pathophysiological effects of CNTNAP2 mutations on axonal physiology and brain myelination are unknown. Here, we have investigated mouse mutants for Cntnap2 and found profound deficiencies in the clustering of Kv1-family potassium channels in the juxtaparanodes of brain myelinated axons. These deficits are associated with a change in the waveform of axonal action potentials and increases in postsynaptic excitatory responses. We also observed that the normal process of myelination is delayed in Cntnap2 mutant mice. This later phenotype is a likely modulator of the developmental expressivity of the stereotyped motor behaviors that characterize Cntnap2 mutant mice. Altogether, our results reveal a mechanism linked to white matter conductivity through which mutation of CNTNAP2 may affect neurodevelopmental outcomes.
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http://dx.doi.org/10.1093/cercor/bhx341DOI Listing
February 2019

Glial M6B stabilizes the axonal membrane at peripheral nodes of Ranvier.

Glia 2018 04 28;66(4):801-812. Epub 2017 Dec 28.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.

Glycoprotein M6B and the closely related proteolipid protein regulate oligodendrocyte myelination in the central nervous system, but their role in the peripheral nervous system is less clear. Here we report that M6B is located at nodes of Ranvier in peripheral nerves where it stabilizes the nodal axolemma. We show that M6B is co-localized and associates with gliomedin at Schwann cell microvilli that are attached to the nodes. Developmental analysis of sciatic nerves, as well as of myelinating Schwann cells/dorsal root ganglion neurons cultures, revealed that M6B is already present at heminodes, which are considered the precursors of mature nodes of Ranvier. However, in contrast to gliomedin, which accumulates at heminodes with or prior to Na channels, we often detected Na channel clusters at heminodes without any associated M6B, indicating that it is not required for initial channel clustering. Consistently, nodal cell adhesion molecules (NF186, NrCAM), ion channels (Nav1.2 and Kv7.2), cytoskeletal proteins (AnkG and βIV spectrin), and microvilli components (pERM, syndecan3, gliomedin), are all present at both heminodes and mature nodes of Ranvier in Gpm6b null mice. Using transmission electron microscopy, we show that the absence of M6B results in progressive appearance of nodal protrusions of the nodal axolemma, that are often accompanied by the presence of enlarged mitochondria. Our results reveal that M6B is a Schwann cell microvilli component that preserves the structural integrity of peripheral nodes of Ranvier.
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http://dx.doi.org/10.1002/glia.23285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5812800PMC
April 2018

Assembly of CNS Nodes of Ranvier in Myelinated Nerves Is Promoted by the Axon Cytoskeleton.

Curr Biol 2017 Apr 16;27(7):1068-1073. Epub 2017 Mar 16.

Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK. Electronic address:

Nodes of Ranvier in the axons of myelinated neurons are exemplars of the specialized cell surface domains typical of polarized cells. They are rich in voltage-gated sodium channels (Nav) and thus underpin rapid nerve impulse conduction in the vertebrate nervous system [1]. Although nodal proteins cluster in response to myelination, how myelin-forming glia influence nodal assembly is poorly understood. An axoglial adhesion complex comprising glial Neurofascin155 and axonal Caspr/Contactin flanks mature nodes [2]. We have shown that assembly of this adhesion complex at the extremities of migrating oligodendroglial processes promotes process convergence along the axon during central nervous system (CNS) node assembly [3]. Here we show that anchorage of this axoglial complex to the axon cytoskeleton is essential for efficient CNS node formation. When anchorage is disrupted, both the adaptor Protein 4.1B and the cytoskeleton protein βII spectrin are mislocalized in the axon, and assembly of the node of Ranvier is significantly delayed. Nodal proteins and migrating oligodendroglial processes are no longer juxtaposed, and single detached nodal complexes replace the symmetrical heminodes found in both the CNS and peripheral nervous system (PNS) during development. We propose that axoglial adhesion complexes contribute to the formation of an interface between cytoskeletal elements enriched in Protein 4.1B and βII spectrin and those enriched in nodal ankyrinG and βIV spectrin. This clusters nascent nodal complexes at heminodes and promotes their timely coalescence to form the mature node of Ranvier. These data demonstrate a role for the axon cytoskeleton in the assembly of a critical neuronal domain, the node of Ranvier.
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http://dx.doi.org/10.1016/j.cub.2017.01.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5387178PMC
April 2017

The paranodal cytoskeleton clusters Na channels at nodes of Ranvier.

Elife 2017 01 30;6. Epub 2017 Jan 30.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.

A high density of Na channels at nodes of Ranvier is necessary for rapid and efficient action potential propagation in myelinated axons. Na+ channel clustering is thought to depend on two axonal cell adhesion molecules that mediate interactions between the axon and myelinating glia at the nodal gap (i.e., NF186) and the paranodal junction (i.e., Caspr). Here we show that while Na channels cluster at nodes in the absence of NF186, they fail to do so in double conditional knockout mice lacking both NF186 and the paranodal cell adhesion molecule Caspr, demonstrating that a paranodal junction-dependent mechanism can cluster Na channels at nodes. Furthermore, we show that paranode-dependent clustering of nodal Na channels requires axonal βII spectrin which is concentrated at paranodes. Our results reveal that the paranodal junction-dependent mechanism of Nachannel clustering is mediated by the spectrin-based paranodal axonal cytoskeleton.
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http://dx.doi.org/10.7554/eLife.21392DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5279941PMC
January 2017

Somatodendritic Expression of JAM2 Inhibits Oligodendrocyte Myelination.

Neuron 2016 Aug 4;91(4):824-836. Epub 2016 Aug 4.

Department of Neurology and Program in Neuroscience, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address:

Myelination occurs selectively around neuronal axons to increase the efficiency and velocity of action potentials. While oligodendrocytes are capable of myelinating permissive structures in the absence of molecular cues, structurally permissive neuronal somata and dendrites remain unmyelinated. Utilizing a purified spinal cord neuron-oligodendrocyte myelinating co-culture system, we demonstrate that disruption of dynamic neuron-oligodendrocyte signaling by chemical cross-linking results in aberrant myelination of the somatodendritic compartment of neurons. We hypothesize that an inhibitory somatodendritic cue is necessary to prevent non-axonal myelination. Using next-generation sequencing and candidate profiling, we identify neuronal junction adhesion molecule 2 (JAM2) as an inhibitory myelin-guidance molecule. Taken together, our results demonstrate that the somatodendritic compartment directly inhibits myelination and suggest a model in which broadly indiscriminate myelination is tailored by inhibitory signaling to meet local myelination requirements.
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http://dx.doi.org/10.1016/j.neuron.2016.07.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4990461PMC
August 2016

Auto-antibodies to contactin-associated protein 1 (Caspr) in two patients with painful inflammatory neuropathy.

Brain 2016 Oct 29;139(Pt 10):2617-2630. Epub 2016 Jul 29.

1 Department of Neurology, University of Würzburg, Germany.

Auto-antibodies against the paranodal proteins neurofascin-155 and contactin-1 have recently been described in patients with chronic inflammatory demyelinating polyradiculoneuropathy and are associated with a distinct clinical phenotype and response to treatment. Contactin-associated protein 1 (Caspr, encoded by CNTNAP1) is a paranodal protein that is attached to neurofascin-155 and contactin-1 (CNTN1) but has not yet been identified as a sole antigen in patients with inflammatory neuropathies. In the present study, we screened a cohort of 35 patients with chronic inflammatory demyelinating polyradiculoneuropathy (age range 20-80, 10 female, 25 male) and 22 patients with Guillain-Barré syndrome (age range 17-86, eight female, 14 male) for autoantibodies against paranodal antigens. We identified two patients, one with chronic inflammatory demyelinating polyradiculoneuropathy and one with Guillain-Barré syndrome, with autoantibodies against Caspr by binding assays using Caspr transfected human embryonic kidney cells and murine teased fibres. IgG3 was the predominant autoantibody subclass in the patient with Guillain-Barré syndrome, IgG4 was predominant in the patient with chronic inflammatory demyelinating polyradiculoneuropathy. Accordingly, complement deposition after binding to HEK293 cells was detectable in the patient with IgG3 autoantibodies only, not in the patient with IgG4. Severe disruption of the paranodal and nodal architecture was detectable in teased fibres of the sural nerve biopsy and in dermal myelinated fibres, supporting the notion of the paranodes being the site of pathology. Deposition of IgG at the paranodes was detected in teased fibre preparations of the sural nerve, further supporting the pathogenicity of anti-Caspr autoantibodies. Pain was one of the predominant findings in both patients, possibly reflected by binding of patients' IgG to TRPV1 immunoreactive dorsal root ganglia neurons. Our results demonstrate that the paranodal protein Caspr constitutes a new antigen that leads to autoantibody generation as part of the novel entity of neuropathies associated with autoantibodies against paranodal proteins.
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http://dx.doi.org/10.1093/brain/aww189DOI Listing
October 2016

Specific inhibition of secreted NRG1 types I-II by heparin enhances Schwann Cell myelination.

Glia 2016 07 3;64(7):1227-34. Epub 2016 May 3.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel.

Primary cultures of mixed neuron and Schwann cells prepared from dorsal root ganglia (DRG) are extensively used as a model to study myelination. These dissociated DRG cultures have the particular advantage of bypassing the difficulty in purifying mouse Schwann cells, which is often required when using mutant mice. However, the drawback of this experimental system is that it yields low amounts of myelin. Here we report a simple and efficient method to enhance myelination in vitro. We show that the addition of heparin or low molecular weight heparin to mixed DRG cultures markedly increases Schwann cells myelination. The myelin promoting activity of heparin results from specific inhibition of the soluble immunoglobulin (Ig)-containing isoforms of neuregulin 1 (i.e., NRG1 types I and II) that negatively regulates myelination. Heparin supplement provides a robust and reproducible method to increase myelination in a simple and commonly used culture system. GLIA 2016;64:1227-1234.
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http://dx.doi.org/10.1002/glia.22995DOI Listing
July 2016

G protein-coupled receptor 37 is a negative regulator of oligodendrocyte differentiation and myelination.

Nat Commun 2016 Mar 10;7:10884. Epub 2016 Mar 10.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.

While the formation of myelin by oligodendrocytes is critical for the function of the central nervous system, the molecular mechanism controlling oligodendrocyte differentiation remains largely unknown. Here we identify G protein-coupled receptor 37 (GPR37) as an inhibitor of late-stage oligodendrocyte differentiation and myelination. GPR37 is enriched in oligodendrocytes and its expression increases during their differentiation into myelin forming cells. Genetic deletion of Gpr37 does not affect the number of oligodendrocyte precursor cells, but results in precocious oligodendrocyte differentiation and hypermyelination. The inhibition of oligodendrocyte differentiation by GPR37 is mediated by suppression of an exchange protein activated by cAMP (EPAC)-dependent activation of Raf-MAPK-ERK1/2 module and nuclear translocation of ERK1/2. Our data suggest that GPR37 regulates central nervous system myelination by controlling the transition from early-differentiated to mature oligodendrocytes.
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http://dx.doi.org/10.1038/ncomms10884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4792952PMC
March 2016

Expression of Cntnap2 (Caspr2) in multiple levels of sensory systems.

Mol Cell Neurosci 2016 Jan 2;70:42-53. Epub 2015 Dec 2.

Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address:

Genome-wide association studies and copy number variation analyses have linked contactin associated protein 2 (Caspr2, gene name Cntnap2) with autism spectrum disorder (ASD). In line with these findings, mice lacking Caspr2 (Cntnap2(-/-)) were shown to have core autism-like deficits including abnormal social behavior and communication, and behavior inflexibility. However the role of Caspr2 in ASD pathogenicity remains unclear. Here we have generated a new Caspr2:tau-LacZ knock-in reporter line (Cntnap2(tlacz/tlacz)), which enabled us to monitor the neuronal circuits in the brain expressing Caspr2. We show that Caspr2 is expressed in many brain regions and produced a comprehensive report of Caspr2 expression. Moreover, we found that Caspr2 marks all sensory modalities: it is expressed in distinct brain regions involved in different sensory processings and is present in all primary sensory organs. Olfaction-based behavioral tests revealed that mice lacking Caspr2 exhibit abnormal response to sensory stimuli and lack preference for novel odors. These results suggest that loss of Caspr2 throughout the sensory system may contribute to the sensory manifestations frequently observed in ASD.
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http://dx.doi.org/10.1016/j.mcn.2015.11.012DOI Listing
January 2016

The Nodes of Ranvier: Molecular Assembly and Maintenance.

Cold Spring Harb Perspect Biol 2015 Sep 9;8(3):a020495. Epub 2015 Sep 9.

Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel.

Action potential (AP) propagation in myelinated nerves requires clustered voltage gated sodium and potassium channels. These channels must be specifically localized to nodes of Ranvier where the AP is regenerated. Several mechanisms have evolved to facilitate and ensure the correct assembly and stabilization of these essential axonal domains. This review highlights the current understanding of the axon intrinsic and glial extrinsic mechanisms that control the formation and maintenance of the nodes of Ranvier in both the peripheral nervous system (PNS) and central nervous system (CNS).
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http://dx.doi.org/10.1101/cshperspect.a020495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772103PMC
September 2015

Comprehensive Analysis of the 16p11.2 Deletion and Null Cntnap2 Mouse Models of Autism Spectrum Disorder.

PLoS One 2015 14;10(8):e0134572. Epub 2015 Aug 14.

Roche, Basel, Switzerland.

Autism spectrum disorder comprises several neurodevelopmental conditions presenting symptoms in social communication and restricted, repetitive behaviors. A major roadblock for drug development for autism is the lack of robust behavioral signatures predictive of clinical efficacy. To address this issue, we further characterized, in a uniform and rigorous way, mouse models of autism that are of interest because of their construct validity and wide availability to the scientific community. We implemented a broad behavioral battery that included but was not restricted to core autism domains, with the goal of identifying robust, reliable phenotypes amenable for further testing. Here we describe comprehensive findings from two known mouse models of autism, obtained at different developmental stages, using a systematic behavioral test battery combining standard tests as well as novel, quantitative, computer-vision based systems. The first mouse model recapitulates a deletion in human chromosome 16p11.2, found in 1% of individuals with autism. The second mouse model harbors homozygous null mutations in Cntnap2, associated with autism and Pitt-Hopkins-like syndrome. Consistent with previous results, 16p11.2 heterozygous null mice, also known as Del(7Slx1b-Sept1)4Aam weighed less than wild type littermates displayed hyperactivity and no social deficits. Cntnap2 homozygous null mice were also hyperactive, froze less during testing, showed a mild gait phenotype and deficits in the three-chamber social preference test, although less robust than previously published. In the open field test with exposure to urine of an estrous female, however, the Cntnap2 null mice showed reduced vocalizations. In addition, Cntnap2 null mice performed slightly better in a cognitive procedural learning test. Although finding and replicating robust behavioral phenotypes in animal models is a challenging task, such functional readouts remain important in the development of therapeutics and we anticipate both our positive and negative findings will be utilized as a resource for the broader scientific community.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134572PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537259PMC
May 2016

Myelin-associated glycoprotein gene mutation causes Pelizaeus-Merzbacher disease-like disorder.

Brain 2015 Sep 15;138(Pt 9):2521-36. Epub 2015 Jul 15.

2 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.

Pelizaeus-Merzbacher disease is an X-linked hypomyelinating leukodystrophy caused by mutations or rearrangements in PLP1. It presents in infancy with nystagmus, jerky head movements, hypotonia and developmental delay evolving into spastic tetraplegia with optic atrophy and variable movement disorders. A clinically similar phenotype caused by recessive mutations in GJC2 is known as Pelizaeus-Merzbacher-like disease. Both genes encode proteins associated with myelin. We describe three siblings of a consanguineous family manifesting the typical infantile-onset Pelizaeus-Merzbacher disease-like phenotype slowly evolving into a form of complicated hereditary spastic paraplegia with mental retardation, dysarthria, optic atrophy and peripheral neuropathy in adulthood. Magnetic resonance imaging and spectroscopy were consistent with a demyelinating leukodystrophy. Using genetic linkage and exome sequencing, we identified a homozygous missense c.399C>G; p.S133R mutation in MAG. This gene, previously associated with hereditary spastic paraplegia, encodes myelin-associated glycoprotein, which is involved in myelin maintenance and glia-axon interaction. This mutation is predicted to destabilize the protein and affect its tertiary structure. Examination of the sural nerve biopsy sample obtained in childhood in the oldest sibling revealed complete absence of myelin-associated glycoprotein accompanied by ill-formed onion-bulb structures and a relatively thin myelin sheath of the affected axons. Immunofluorescence, cell surface labelling, biochemical analysis and mass spectrometry-based proteomics studies in a variety of cell types demonstrated a devastating effect of the mutation on post-translational processing, steady state expression and subcellular localization of myelin-associated glycoprotein. In contrast to the wild-type protein, the p.S133R mutant was retained in the endoplasmic reticulum and was subjected to endoplasmic reticulum-associated protein degradation by the proteasome. Our findings identify involvement of myelin-associated glycoprotein in this family with a disorder affecting the central and peripheral nervous system, and suggest that loss of the protein function is responsible for the unique clinical phenotype.
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http://dx.doi.org/10.1093/brain/awv204DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4643626PMC
September 2015

The myelin proteolipid plasmolipin forms oligomers and induces liquid-ordered membranes in the Golgi complex.

J Cell Sci 2015 Jul 22;128(13):2293-302. Epub 2015 May 22.

Department of Pathology, Sackler School of Medicine, Tel-Aviv 69978, Israel

Myelin comprises a compactly stacked massive surface area of protein-poor thick membrane that insulates axons to allow fast signal propagation. Increasing levels of the myelin protein plasmolipin (PLLP) were correlated with post-natal myelination; however, its function is unknown. Here, the intracellular localization and dynamics of PLLP were characterized in primary glial and cultured cells using fluorescently labeled PLLP and antibodies against PLLP. PLLP localized to and recycled between the plasma membrane and the Golgi complex. In the Golgi complex, PLLP forms oligomers based on fluorescence resonance energy transfer (FRET) analyses. PLLP oligomers blocked Golgi to plasma membrane transport of the secretory protein vesicular stomatitis virus G protein (VSVG), but not of a VSVG mutant with an elongated transmembrane domain. Laurdan staining analysis showed that this block is associated with PLLP-induced proliferation of liquid-ordered membranes. These findings show the capacity of PLLP to assemble potential myelin membrane precursor domains at the Golgi complex through its oligomerization and ability to attract liquid-ordered lipids. These data support a model in which PLLP functions in myelin biogenesis through organization of myelin liquid-ordered membranes in the Golgi complex.
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http://dx.doi.org/10.1242/jcs.166249DOI Listing
July 2015

Synaptic abnormalities and cytoplasmic glutamate receptor aggregates in contactin associated protein-like 2/Caspr2 knockout neurons.

Proc Natl Acad Sci U S A 2015 May 27;112(19):6176-81. Epub 2015 Apr 27.

Departments of Physiology and Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL 60611;

Central glutamatergic synapses and the molecular pathways that control them are emerging as common substrates in the pathogenesis of mental disorders. Genetic variation in the contactin associated protein-like 2 (CNTNAP2) gene, including copy number variations, exon deletions, truncations, single nucleotide variants, and polymorphisms have been associated with intellectual disability, epilepsy, schizophrenia, language disorders, and autism. CNTNAP2, encoded by Cntnap2, is required for dendritic spine development and its absence causes disease-related phenotypes in mice. However, the mechanisms whereby CNTNAP2 regulates glutamatergic synapses are not known, and cellular phenotypes have not been investigated in Cntnap2 knockout neurons. Here we show that CNTNAP2 is present in dendritic spines, as well as axons and soma. Structured illumination superresolution microscopy reveals closer proximity to excitatory, rather than inhibitory synaptic markers. CNTNAP2 does not promote the formation of synapses and cultured neurons from Cntnap2 knockout mice do not show early defects in axon and dendrite outgrowth, suggesting that CNTNAP2 is not required at this stage. However, mature neurons from knockout mice show reduced spine density and levels of GluA1 subunits of AMPA receptors in spines. Unexpectedly, knockout neurons show large cytoplasmic aggregates of GluA1. Here we characterize, for the first time to our knowledge, synaptic phenotypes in Cntnap2 knockout neurons and reveal a novel role for CNTNAP2 in GluA1 trafficking. Taken together, our findings provide insight into the biological roles of CNTNAP2 and into the pathogenesis of CNTNAP2-associated neuropsychiatric disorders.
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http://dx.doi.org/10.1073/pnas.1423205112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4434727PMC
May 2015
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