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Nevoux J, Alexandru M, Bellocq T, Tanaka L, Hayashi Y, Watabe T, Lahlou H, Tani K, Edge ASB. An antibody to RGMa promotes regeneration of cochlear synapses after noise exposure. Sci Rep 2021; 11:2937. [PMID: 33536466 PMCID: PMC7859405 DOI: 10.1038/s41598-021-81294-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 01/05/2021] [Indexed: 11/09/2022] Open
Abstract
Auditory neuropathy is caused by the loss of afferent input to the brainstem via the components of the neural pathway comprising inner hair cells and the first order neurons of the spiral ganglion. Recent work has identified the synapse between cochlear primary afferent neurons and sensory hair cells as a particularly vulnerable component of this pathway. Loss of these synapses due to noise exposure or aging results in the pathology identified as hidden hearing loss, an initial stage of cochlear dysfunction that goes undetected in standard hearing tests. We show here that repulsive axonal guidance molecule a (RGMa) acts to prevent regrowth and synaptogenesis of peripheral auditory nerve fibers with inner hair cells. Treatment of noise-exposed animals with an anti-RGMa blocking antibody regenerated inner hair cell synapses and resulted in recovery of wave-I amplitude of the auditory brainstem response, indicating effective reversal of synaptopathy.
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Affiliation(s)
- Jerome Nevoux
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Mihaela Alexandru
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Thomas Bellocq
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Lei Tanaka
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Yushi Hayashi
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Takahisa Watabe
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Hanae Lahlou
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Kohsuke Tani
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA
| | - Albert S B Edge
- Department of Otololaryngology, Harvard Medical School, Boston, MA, 02115, USA. .,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114, USA. .,Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA, 02115, USA. .,Harvard Stem Cell Institute, Cambridge, MA, 02138, USA.
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Siebold C, Yamashita T, Monnier PP, Mueller BK, Pasterkamp RJ. RGMs: Structural Insights, Molecular Regulation, and Downstream Signaling. Trends Cell Biol 2017; 27:365-378. [PMID: 28007423 PMCID: PMC5404723 DOI: 10.1016/j.tcb.2016.11.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 11/27/2016] [Accepted: 11/28/2016] [Indexed: 12/20/2022]
Abstract
Although originally discovered as neuronal growth cone-collapsing factors, repulsive guidance molecules (RGMs) are now known as key players in many fundamental processes, such as cell migration, differentiation, iron homeostasis, and apoptosis, during the development and homeostasis of many tissues and organs, including the nervous, skeletal, and immune systems. Furthermore, three RGMs (RGMa, RGMb/DRAGON, and RGMc/hemojuvelin) have been linked to the pathogenesis of various disorders ranging from multiple sclerosis (MS) to cancer and juvenile hemochromatosis (JHH). While the molecular details of these (patho)biological effects and signaling modes have long remained unknown, recent studies unveil several exciting and novel aspects of RGM processing, ligand-receptor interactions, and downstream signaling. In this review, we highlight recent advances in the mechanisms-of-action and function of RGM proteins.
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Affiliation(s)
- Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Philippe P Monnier
- Krembil Research Institute, 60 Leonard Street, M5T 2S8, Toronto, ONT, Canada
| | - Bernhard K Mueller
- Neuroscience Discovery Research, Abbvie, Knollstrasse 50, 67061 Ludwigshafen, Germany
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
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Martins AF, Xavier Neto J, Azambuja A, Sereno ML, Figueira A, Campos-Junior PH, Rosário MF, Toledo CBB, Silva GAB, Kitten GT, Coutinho LL, Dietrich S, Jorge EC. Repulsive Guidance Molecules a, b and c Are Skeletal Muscle Proteins, and Repulsive Guidance Molecule a Promotes Cellular Hypertrophy and Is Necessary for Myotube Fusion. Cells Tissues Organs 2015; 200:326-38. [PMID: 26397945 DOI: 10.1159/000433491] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2015] [Indexed: 11/19/2022] Open
Abstract
Repulsive guidance molecules (RGMs) compose a family of glycosylphosphatidylinositol (GPI)-anchored axon guidance molecules and perform several functions during neural development. New evidence has suggested possible new roles for these axon guidance molecules during skeletal muscle development, which has not been investigated thus far. In the present study, we show that RGMa, RGMb and RGMc are all induced during skeletal muscle differentiation in vitro. Immunolocalization performed on adult skeletal muscle cells revealed that RGMa, RGMb and RGMc are sarcolemmal proteins. Additionally, RGMa was found to be a sarcoplasmic protein with a surprisingly striated pattern. RGMa colocalization with known sarcoplasmic proteins suggested that this axon guidance molecule is a skeletal muscle sarcoplasmic protein. Western blot analysis revealed two RGMa fragments of 60 and 33 kDa, respectively, in adult skeletal muscle samples. RGMa phenotypes in skeletal muscle cells (C2C12 and primary myoblasts) were also investigated. RGMa overexpression produced hypertrophic cells, whereas RGMa knockdown resulted in the opposite phenotype. RGMa knockdown also blocked myotube formation in both skeletal muscle cell types. Our results are the first to show an axon guidance molecule as a skeletal muscle sarcoplasmic protein and to include RGMa in a system that regulates skeletal muscle cell size and differentiation.
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Affiliation(s)
- Aline Fagundes Martins
- Departamento de Morfologia, Instituto de Cix00EA;ncias Biolx00F3;gicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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ϒ-secretase and LARG mediate distinct RGMa activities to control appropriate layer targeting within the optic tectum. Cell Death Differ 2015; 23:442-53. [PMID: 26292756 PMCID: PMC5072438 DOI: 10.1038/cdd.2015.111] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 07/11/2015] [Accepted: 07/02/2015] [Indexed: 11/15/2022] Open
Abstract
While a great deal of progress has been made in understanding the molecular mechanisms that regulate retino-tectal mapping, the determinants that target retinal projections to specific layers of the optic tectum remain elusive. Here we show that two independent RGMa-peptides, C- and N-RGMa, activate two distinct intracellular pathways to regulate axonal growth. C-RGMa utilizes a Leukemia-associated RhoGEF (LARG)/Rho/Rock pathway to inhibit axonal growth. N-RGMa on the other hand relies on ϒ-secretase cleavage of the intracellular portion of Neogenin to generate an intracellular domain (NeICD) that uses LIM-only protein 4 (LMO4) to block growth. In the developing tectum (E18), overexpression of C-RGMa and dominant-negative LARG (LARG-PDZ) induced overshoots in the superficial tectal layer but not in deeper tectal layers. In younger embryos (E12), C-RGMa and LARG-PDZ prevented ectopic projections toward deeper tectal layers, indicating that C-RGMa may act as a barrier to descending axons. In contrast both N-RGMa and NeICD overexpression resulted in aberrant axonal-paths, all of which suggests that it is a repulsive guidance molecule. Thus, two RGMa fragments activate distinct pathways resulting in different axonal responses. These data reveal how retinal projections are targeted to the appropriate layer in their target tissue.
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Hosseini M, Haji-Fatahaliha M, Jadidi-Niaragh F, Majidi J, Yousefi M. The use of nanoparticles as a promising therapeutic approach in cancer immunotherapy. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2015; 44:1051-61. [DOI: 10.3109/21691401.2014.998830] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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CRMP-2 is involved in axon growth inhibition induced by RGMa in vitro and in vivo. Mol Neurobiol 2012; 47:903-13. [PMID: 23275173 DOI: 10.1007/s12035-012-8385-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 12/04/2012] [Indexed: 10/27/2022]
Abstract
Repulsive guidance molecule-a (RGMa) is associated with axon growth inhibition in different central nervous system (CNS) injuries, but its signaling pathways remain unclear. We examined the involvement of collapsin response mediator protein-2 (CRMP-2), a common downstream target of Rho-kinase and GSK-3β, in vitro by culturing neonatal rat primary cortical neurons with RGMa protein, Rho-kinase inhibitor (Y-27632), and GSK-3β inhibitor. We examined CRMP-2 in vivo by suppressing RGMa expression using recombinant adenovirus (rAd-shRGMa) in a rat MCAO/reperfusion model. RGMa induced neurite retraction and CRMP-2 phosphorylation in vitro, which were reversed by either Rho-kinase or GSK-3β inhibitors. After MCAO/reperfusion in rats, pCRMP-2 protein was greatly increased in the ischemic cortex, axons were damaged severely, Neurofilament-200 (NF-200) expression was significantly decreased, and neurological deficits were significant, which were all improved by down-regulating RGMa. We concluded RGMa inhibits axon growth by phosphorylating CRMP-2 via both Rho-kinase and GSK-3β signaling pathways.
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Cockburn DM, Charish J, Tassew NG, Eubanks J, Bremner R, Macchi P, Monnier PP. The double-stranded RNA-binding protein Staufen 2 regulates eye size. Mol Cell Neurosci 2012; 51:101-11. [PMID: 22940085 DOI: 10.1016/j.mcn.2012.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 08/13/2012] [Accepted: 08/16/2012] [Indexed: 12/25/2022] Open
Abstract
Regulation of tissue size is a poorly understood process. Mammalian Staufen 2 (Stau2) is a double-stranded mRNA binding protein known to regulate dendrite formation in vitro as well as cell survival and migration in vivo. Three Stau2 isoforms have been identified in the brain of mammals. Here we show that all these Stau2 isoforms are also expressed in the developing eye of chicken embryos. Strikingly, ectopic expression of Stau2 was sufficient to increase eye size, suggesting a novel biological role of Stau2 in eye morphogenesis. Moreover, down regulation of Stau2 in vivo resulted in a small eye. Microphthalmia was not associated with either increased cell death or differentiation but with reduced cell proliferation. Rescue experiments showed that all three Stau2 isoforms present in the developing eye could prevent microphthalmia. Finally, we showed that Stau2 silencing decreased HES-1 and Sox-2 in the developing eye. These data highlight a new biological function for Stau2 and suggest that translation control of specific Stau2-associated transcripts may be a key regulator of tissue size.
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Affiliation(s)
- Diane M Cockburn
- Toronto Western Research Institute, Genetics and Development Division, MCL-6-415, Toronto M5T 2S8, Ontario, Canada
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Lah GJ, Key B. Dual roles of the chemorepellent axon guidance molecule RGMa in establishing pioneering axon tracts and neural fate decisions in embryonic vertebrate forebrain. Dev Neurobiol 2012; 72:1458-70. [DOI: 10.1002/dneu.22010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 12/01/2011] [Accepted: 01/19/2012] [Indexed: 11/11/2022]
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Tassew N, Charish J, Seidah N, Monnier P. SKI-1 and Furin Generate Multiple RGMa Fragments that Regulate Axonal Growth. Dev Cell 2012; 22:391-402. [DOI: 10.1016/j.devcel.2011.11.022] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 09/19/2011] [Accepted: 11/21/2011] [Indexed: 11/26/2022]
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Novel roles of the chemorepellent axon guidance molecule RGMa in cell migration and adhesion. Mol Cell Biol 2012; 32:968-80. [PMID: 22215618 DOI: 10.1128/mcb.06128-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The repulsive guidance molecule A (RGMa) is a contact-mediated axon guidance molecule that has significant roles in central nervous system (CNS) development. Here we have examined whether RGMa has novel roles in cell migration and cell adhesion outside the nervous system. RGMa was found to stimulate cell migration from Xenopus animal cap explants in a neogenin-dependent and BMP-independent manner. RGMa also stimulated the adhesion of Xenopus animal cap cells, and this adhesion was dependent on neogenin and independent of calcium. To begin to functionally characterize the role of specific domains in RGMa, we assessed the migratory and adhesive activities of deletion mutants. RGMa lacking the partial von Willebrand factor type D (vWF) domain preferentially perturbed cell adhesion, while mutants lacking the RGD motif affected cell migration. We also revealed that manipulating the levels of RGMa in vivo caused major migration defects during Xenopus gastrulation. We have revealed here novel roles of RGMa in cell migration and adhesion and demonstrated that perturbations to the homeostasis of RGMa expression can severely disrupt major morphogenetic events. These results have implications for understanding the role of RGMa in both health and disease.
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Schnichels S, Heiduschka P, Julien S. RGMA and neogenin protein expression are influenced by lens injury following optic nerve crush in the rat retina. Graefes Arch Clin Exp Ophthalmol 2011; 250:39-50. [PMID: 21887516 DOI: 10.1007/s00417-011-1791-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 07/14/2011] [Accepted: 07/28/2011] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The death and the failure of neurons to regenerate their axons after lesion of the central nervous system in mammals, as in the case of spinal cord injury and optic nerve trauma, remain a challenge. In this study, we focused on the repulsive guidance molecule A (RGMA) and its receptor neogenin. Since it was reported that RGMA+ cells accumulate in lesioned areas after spinal cord injury, brain trauma, and optic nerve crush, and curiously, anti-apoptotic effects of RGMA were also described, we investigated the role of RGMA and neogenin in the retina after optic nerve crush (ONC). METHODS We evaluated the spatial and temporal protein pattern of RGMA and neogenin in the rat retina without (non-regenerating model) or with (regenerating model) lens injury (LI). We investigated the presence of RGMA, neogenin and other proteins at up to nine time points (6 h-20 days post-surgery) by performing immunohistochemistry and Western blots. RESULTS Independent of the treatment, RGMA protein was present in the nuclear layers (NLs), plexiform layers (PLs), nerve fiber layer (NFL), and in retinal ganglion cells (RGCs) of the rat retina. RGC and nerve fibers were always RGMA+. Further RGMA+ cells in the retina were blood vessel endothelial cells, astrocytes, Müller cells, and some microglial cells. The RGMA pattern for the specific retinal cells resembled those of previously published data. The neogenin pattern was congruent to the RGMA pattern. Western blots of retinal tissue showed further RGMA+ products only in LI animals. Furthermore, a higher amount of RGMA was found in the retinae of ONC + LI rats compared to ONC rats. CONCLUSIONS Although a difference in the localization of RGMA is not obvious, the difference in the amount of RGMA is striking, the higher amount of RGMA in the retinae of ONC + LI rats compared to ONC rats indicates a role for RGMA during degeneration/regeneration processes. Our results are consistent with several reported neuroprotective effects of RGMA. Our new data showing the upregulation of RGMA after ONC in our regenerating model (plus LI) confirm these findings conducted in different settings.
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Affiliation(s)
- Sven Schnichels
- Centre for Ophthalmology, University Eye Hospital, Tübingen, Germany
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Schnichels S, Heiduschka P, Julien S. Different spatial and temporal protein expressions of repulsive guidance molecule a and neogenin in the rat optic nerve after optic nerve crush with and without lens injury. J Neurosci Res 2011; 89:490-505. [DOI: 10.1002/jnr.22584] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 11/10/2010] [Accepted: 11/22/2010] [Indexed: 12/30/2022]
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Koeberle PD, Tura A, Tassew NG, Schlichter LC, Monnier PP. The repulsive guidance molecule, RGMa, promotes retinal ganglion cell survival in vitro and in vivo. Neuroscience 2010; 169:495-504. [PMID: 20457227 DOI: 10.1016/j.neuroscience.2010.04.079] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 04/12/2010] [Accepted: 04/30/2010] [Indexed: 10/19/2022]
Abstract
The repulsive guidance molecule, RGMa, and its receptor Neogenin, regulate neuronal cell death during development, but little is known about their expression and roles in the adult CNS. Here, we show that Neogenin is expressed in the adult rodent retina, particularly on retinal ganglion cells. To determine whether the Neogenin/RGMa pathway is important in the fully developed retina, we examined its contribution to damage-induced neurodegeneration. The effects of RGMa on survival of retinal ganglion cells (RGCs) were examined in vitro and in vivo. Using cultured whole-mount retinal explants, we showed that the addition of RGMa increased RGC survival and that this effect was mediated by the Neogenin receptor. Immunohistochemical analysis indicated that the inhibition of cell death by RGMa resulted from reduced caspase-3 activation. Then, using an in vivo model of RGC apoptosis after optic nerve transection, we demonstrated that intraocular injection of RGMa at 3 and 7 days after axotomy greatly reduced RGC death 14 days postaxotomy. This study provides the first evidence that RGMa is a molecular target for neuroprotection in retinal pathologies, and suggests that targeting "dependence receptors" such as Neogenin has therapeutic potential for the treatment of neuropathologies in the adult CNS.
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Affiliation(s)
- P D Koeberle
- Division of Anatomy, Department of Surgery, University of Toronto, Canada.
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Cyclops. Can J Ophthalmol 2009. [DOI: 10.1016/10.3129/i09-035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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