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Chambel SS, Cruz CD. Axonal growth inhibitors and their receptors in spinal cord injury: from biology to clinical translation. Neural Regen Res 2023; 18:2573-2581. [PMID: 37449592 DOI: 10.4103/1673-5374.373674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Abstract
Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelin-associated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19 (that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the RhoA/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.
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Affiliation(s)
- Sílvia Sousa Chambel
- Experimental Biology Unit, Department of Biomedicine, Faculty of Medicine of Porto; Translational NeuroUrology, Instituto de Investigação e Inovação em Saúde-i3S and IBMC, Universidade do Porto, Porto, Portugal
| | - Célia Duarte Cruz
- Experimental Biology Unit, Department of Biomedicine, Faculty of Medicine of Porto; Translational NeuroUrology, Instituto de Investigação e Inovação em Saúde-i3S and IBMC, Universidade do Porto, Porto, Portugal
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2
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Shimizu M, Shiraishi N, Tada S, Sasaki T, Beck G, Nagano S, Kinoshita M, Sumi H, Sugimoto T, Ishida Y, Koda T, Ishikura T, Sugiyama Y, Kihara K, Kanakura M, Nakajima T, Takeda S, Takahashi MP, Yamashita T, Okuno T, Mochizuki H. RGMa collapses the neuronal actin barrier against disease-implicated protein and exacerbates ALS. SCIENCE ADVANCES 2023; 9:eadg3193. [PMID: 37992159 PMCID: PMC10665002 DOI: 10.1126/sciadv.adg3193] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 10/23/2023] [Indexed: 11/24/2023]
Abstract
Repulsive guidance molecule A (RGMa) was originally identified as a neuronal growth cone-collapsing factor. Previous reports have demonstrated the multifunctional roles of RGMa mediated by neogenin1. However, the pathogenic involvement of RGMa in amyotrophic lateral sclerosis (ALS) remains unclear. Here, we demonstrated that RGMa concentration was elevated in the cerebrospinal fluid of both patients with ALS and transgenic mice overexpressing the mutant human superoxide dismutase1 (mSOD1 mice). Treatment with humanized anti-RGMa monoclonal antibody ameliorated the clinical symptoms in mSOD1 mice. Histochemical analysis revealed that the anti-RGMa antibody significantly decreased mutant SOD1 protein accumulation in the motor neurons of mSOD1 mice via inhibition of actin depolymerization. In vitro analysis revealed that the anti-RGMa antibody inhibited the cellular uptake of the mutant SOD1 protein, presumably by reinforcing the neuronal actin barrier. Collectively, these data suggest that RGMa leads to the collapse of the neuronal actin barrier and promotes aberrant protein deposition, resulting in exacerbation of the ALS pathology.
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Affiliation(s)
- Mikito Shimizu
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Naoyuki Shiraishi
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Satoru Tada
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Clinical Research, National Hospital Organization Osaka-Minami Medical Center, Kawachinagano, Osaka, Japan
| | - Tsutomu Sasaki
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Goichi Beck
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Seiichi Nagano
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Neurotherapeutics, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Makoto Kinoshita
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Hisae Sumi
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Neurology, Higashiosaka City Medical Center, Higashiosaka, Osaka, Japan
| | - Tomoyuki Sugimoto
- Graduate School of Data Science, Shiga University, Hikone, Shiga, Japan
| | - Yoko Ishida
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Toru Koda
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Teruyuki Ishikura
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Neurology, Higashiosaka City Medical Center, Higashiosaka, Osaka, Japan
| | - Yasuko Sugiyama
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Keigo Kihara
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Minami Kanakura
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Health Sciences, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Tsuneo Nakajima
- Department of Geriatric and General Medicine, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Shuko Takeda
- Department of Clinical Gene Therapy, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Osaka Psychiatric Research Center, Osaka Psychiatric Medical Center, Hirakata, Osaka, Japan
| | - Masanori P. Takahashi
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Health Sciences, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Tatsusada Okuno
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Hideki Mochizuki
- Department of Neurology, Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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3
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Rapti G. Regulation of axon pathfinding by astroglia across genetic model organisms. Front Cell Neurosci 2023; 17:1241957. [PMID: 37941606 PMCID: PMC10628440 DOI: 10.3389/fncel.2023.1241957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 09/07/2023] [Indexed: 11/10/2023] Open
Abstract
Glia and neurons are intimately associated throughout bilaterian nervous systems, and were early proposed to interact for patterning circuit assembly. The investigations of circuit formation progressed from early hypotheses of intermediate guideposts and a "glia blueprint", to recent genetic and cell manipulations, and visualizations in vivo. An array of molecular factors are implicated in axon pathfinding but their number appears small relatively to circuit complexity. Comprehending this circuit complexity requires to identify unknown factors and dissect molecular topographies. Glia contribute to both aspects and certain studies provide molecular and functional insights into these contributions. Here, I survey glial roles in guiding axon navigation in vivo, emphasizing analogies, differences and open questions across major genetic models. I highlight studies pioneering the topic, and dissect recent findings that further advance our current molecular understanding. Circuits of the vertebrate forebrain, visual system and neural tube in zebrafish, mouse and chick, the Drosophila ventral cord and the C. elegans brain-like neuropil emerge as major contexts to study glial cell functions in axon navigation. I present astroglial cell types in these models, and their molecular and cellular interactions that drive axon guidance. I underline shared principles across models, conceptual or technical complications, and open questions that await investigation. Glia of the radial-astrocyte lineage, emerge as regulators of axon pathfinding, often employing common molecular factors across models. Yet this survey also highlights different involvements of glia in embryonic navigation or pioneer axon pathfinding, and unknowns in the molecular underpinnings of glial cell functions. Future cellular and molecular investigations should complete the comprehensive view of glial roles in circuit assembly.
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Affiliation(s)
- Georgia Rapti
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Rome, Italy
- Interdisciplinary Center of Neurosciences, Heidelberg University, Heidelberg, Germany
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4
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Sempert K, Shohayeb B, Lanoue V, O'Brien EA, Flores C, Cooper HM. RGMa and Neogenin control dendritic spine morphogenesis via WAVE Regulatory Complex-mediated actin remodeling. Front Mol Neurosci 2023; 16:1253801. [PMID: 37928069 PMCID: PMC10620725 DOI: 10.3389/fnmol.2023.1253801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/06/2023] [Indexed: 11/07/2023] Open
Abstract
Structural plasticity, the ability of dendritic spines to change their volume in response to synaptic stimulation, is an essential determinant of synaptic strength and long-term potentiation (LTP), the proposed cellular substrate for learning and memory. Branched actin polymerization is a major force driving spine enlargement and sustains structural plasticity. The WAVE Regulatory Complex (WRC), a pivotal branched actin regulator, controls spine morphology and therefore structural plasticity. However, the molecular mechanisms that govern WRC activation during spine enlargement are largely unknown. Here we identify a critical role for Neogenin and its ligand RGMa (Repulsive Guidance Molecule a) in promoting spine enlargement through the activation of WRC-mediated branched actin remodeling. We demonstrate that Neogenin regulates WRC activity by binding to the highly conserved Cyfip/Abi binding pocket within the WRC. We find that after Neogenin or RGMa depletion, the proportions of filopodia and immature thin spines are dramatically increased, and the number of mature mushroom spines concomitantly decreased. Wildtype Neogenin, but not Neogenin bearing mutations in the Cyfip/Abi binding motif, is able to rescue the spine enlargement defect. Furthermore, Neogenin depletion inhibits actin polymerization in the spine head, an effect that is not restored by the mutant. We conclude that RGMa and Neogenin are critical modulators of WRC-mediated branched actin polymerization promoting spine enlargement. This study also provides mechanistic insight into Neogenin's emerging role in LTP induction.
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Affiliation(s)
- Kai Sempert
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Belal Shohayeb
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Vanessa Lanoue
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Elizabeth A O'Brien
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Cecilia Flores
- Department of Psychiatry, McGill University, Montréal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
- Douglas Mental Health University Institute, Montréal, QC, Canada
| | - Helen M Cooper
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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5
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Kalluri HV, Rosebraugh MR, Misko TP, Ziemann A, Liu W, Cree BAC. Phase 1 Evaluation of Elezanumab (Anti-Repulsive Guidance Molecule A Monoclonal Antibody) in Healthy and Multiple Sclerosis Participants. Ann Neurol 2023; 93:285-296. [PMID: 36093738 PMCID: PMC10100020 DOI: 10.1002/ana.26503] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 08/01/2022] [Accepted: 09/06/2022] [Indexed: 01/31/2023]
Abstract
OBJECTIVE This study was undertaken to describe the safety, tolerability, pharmacokinetics, and immunogenicity of elezanumab (ABT-555), a fully human monoclonal antibody (mAb) directed against repulsive guidance molecule A (RGMa), in healthy and multiple sclerosis (MS) study participants. METHODS The single-center, first-in-human, single ascending dose (SAD) study evaluated elezanumab (50-1,600mg intravenous [IV] and 150mg subcutaneous) in 47 healthy men and women. The multicenter multiple ascending dose (MAD; NCT02601885) study evaluated elezanumab (150mg, 600mg, and 1,800mg) in 20 adult men and women with MS, receiving either maintenance or no immunomodulatory treatment. RESULTS No pattern of study drug-related adverse events was identified for either the SAD or MAD elezanumab regimens. Across both studies, the Tmax occurred within 4 hours of elezanumab IV infusion, and the harmonic mean of t1/2 ranged between 18.6 and 67.7 days. Following multiple dosing, elezanumab Cmax , area under the curve, and Ctrough increased dose-proportionally and resulted in dose-dependent increases in elezanumab cerebrospinal fluid (CSF) concentrations. Elezanumab CSF penetration was 0.1% to 0.4% across both studies, with CSF levels of free RGMa decreased by >40%. Changes in CSF interleukin-10 (IL-10) and free RGMa demonstrated dose/exposure-dependence. INTERPRETATION The elezanumab pharmacokinetic profile supports monthly, or bimonthly, administration of up to 1,800mg with the option of a loading dose of 3,600mg. Elezanumab partitioning into CSF is within the range expected for mAbs. Reduced CSF levels of free RGMa demonstrate central nervous system target binding of elezanumab with an apparent maximal effect at 1,800mg IV. Exposure-associated increases in CSF IL-10, an anti-inflammatory cytokine with neuroprotective/neurorestorative properties, support potential pathway modulation in MS participants. ANN NEUROL 2023;93:285-296.
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Affiliation(s)
- Hari V Kalluri
- Clinical Pharmacology and Pharmacometrics, AbbVie, North Chicago, IL
| | | | | | | | - Wei Liu
- Clinical Pharmacology and Pharmacometrics, AbbVie, North Chicago, IL
| | - Bruce A C Cree
- Weill Institute of Neurosciences, Department of Neurology, University of California, San Francisco, San Francisco, CA
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Development of Neurogenic Detrusor Overactivity after Thoracic Spinal Cord Injury Is Accompanied by Time-Dependent Changes in Lumbosacral Expression of Axonal Growth Regulators. Int J Mol Sci 2022; 23:ijms23158667. [PMID: 35955811 PMCID: PMC9368817 DOI: 10.3390/ijms23158667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 12/04/2022] Open
Abstract
Thoracic spinal cord injury (SCI) results in urinary dysfunction, which majorly affects the quality of life of SCI patients. Abnormal sprouting of lumbosacral bladder afferents plays a crucial role in this condition. Underlying mechanisms may include changes in expression of regulators of axonal growth, including chondroitin sulphate proteoglycans (CSPGs), myelin-associated inhibitors (MAIs) and repulsive guidance molecules, known to be upregulated at the injury site post SCI. Here, we confirmed lumbosacral upregulation of the growth-associated protein GAP43 in SCI animals with bladder dysfunction, indicating the occurrence of axonal sprouting. Neurocan and Phosphacan (CSPGs), as well as Nogo-A (MAI), at the same spinal segments were upregulated 7 days post injury (dpi) but returned to baseline values 28 dpi. In turn, qPCR analysis of the mRNA levels for receptors of those repulsive molecules in dorsal root ganglia (DRG) neurons showed a time-dependent decrease in receptor expression. In vitro assays with DRG neurons from SCI rats demonstrated that exposure to high levels of NGF downregulated the expression of some, but not all, receptors for those regulators of axonal growth. The present results, therefore, show significant molecular changes at the lumbosacral cord and DRGs after thoracic lesion, likely critically involved in neuroplastic events leading to urinary impairment.
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7
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Mothe AJ, Jacobson PB, Caprelli M, Ulndreaj A, Rahemipour R, Huang L, Monnier PP, Fehlings MG, Tator CH. Delayed administration of elezanumab, a human anti-RGMa neutralizing monoclonal antibody, promotes recovery following cervical spinal cord injury. Neurobiol Dis 2022; 172:105812. [PMID: 35810963 DOI: 10.1016/j.nbd.2022.105812] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/03/2022] [Accepted: 07/04/2022] [Indexed: 11/19/2022] Open
Abstract
Spinal cord injury (SCI) elicits a cascade of degenerative events including cell death, axonal degeneration, and the upregulation of inhibitory molecules which limit repair. Repulsive guidance molecule A (RGMa) is an axon growth inhibitor which is also involved in neuronal cell death and differentiation. SCI causes upregulation of RGMa in the injured rodent, non-human primate, and human spinal cord. Recently, we showed that delayed administration of elezanumab, a high affinity human RGMa-specific monoclonal antibody, promoted neuroprotective and regenerative effects following thoracic SCI. Since most human traumatic SCI is at the cervical level, and level-dependent anatomical and molecular differences may influence pathophysiological responses to injury and treatment, we examined the efficacy of elezanumab and its therapeutic time window of administration in a clinically relevant rat model of cervical impact-compression SCI. Pharmacokinetic analysis of plasma and spinal cord tissue lysate showed comparable levels of RGMa antibodies with delayed administration following cervical SCI. At 12w after SCI, elezanumab promoted long term benefits including perilesional sparing of motoneurons and increased neuroplasticity of key descending pathways involved in locomotion and fine motor function. Elezanumab also promoted growth of corticospinal axons into spinal cord gray matter and enhanced serotonergic innervation of the ventral horn to form synaptic connections caudal to the cervical lesion. Significant recovery in grip and trunk/core strength, locomotion and gait, and spontaneous voiding ability was found in rats treated with elezanumab either immediately post-injury or at 3 h post-SCI, and improvements in specific gait parameters were found when elezanumab was delayed to 24 h post-injury. We also developed a new locomotor score, the Cervical Locomotor Score, a simple and sensitive measure of trunk/core and limb strength and stability during dynamic locomotion.
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Affiliation(s)
- Andrea J Mothe
- Division of Experimental and Translational Neuroscience, Krembil Brain Institute & University Health Network, Toronto, M5T 0S8, ON, Canada.
| | - Peer B Jacobson
- Department of Translational Sciences, AbbVie Inc., North Chicago, IL 60064, USA
| | - Mitchell Caprelli
- Division of Experimental and Translational Neuroscience, Krembil Brain Institute & University Health Network, Toronto, M5T 0S8, ON, Canada
| | - Antigona Ulndreaj
- Division of Experimental and Translational Neuroscience, Krembil Brain Institute & University Health Network, Toronto, M5T 0S8, ON, Canada
| | - Radmehr Rahemipour
- Division of Experimental and Translational Neuroscience, Krembil Brain Institute & University Health Network, Toronto, M5T 0S8, ON, Canada
| | - Lili Huang
- AbbVie Biologics, AbbVie Bioresearch Center, Worcester, MA 01605, USA
| | - Philippe P Monnier
- Division of Experimental and Translational Neuroscience, Krembil Brain Institute & University Health Network, Toronto, M5T 0S8, ON, Canada; Department of Ophthalmology and Vision Science, University of Toronto, Toronto, M5S 3H6, ON, Canada
| | - Michael G Fehlings
- Division of Experimental and Translational Neuroscience, Krembil Brain Institute & University Health Network, Toronto, M5T 0S8, ON, Canada; Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, M5T 2S8, ON, Canada
| | - Charles H Tator
- Division of Experimental and Translational Neuroscience, Krembil Brain Institute & University Health Network, Toronto, M5T 0S8, ON, Canada; Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, M5T 2S8, ON, Canada.
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8
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Abstract
This article reviews the discovery of PCSK9, its structure-function characteristics, and its presently known and proposed novel biological functions. The major critical function of PCSK9 deduced from human and mouse studies, as well as cellular and structural analyses, is its role in increasing the levels of circulating low-density lipoprotein (LDL)-cholesterol (LDLc), via its ability to enhance the sorting and escort of the cell surface LDL receptor (LDLR) to lysosomes. This implicates the binding of the catalytic domain of PCSK9 to the EGF-A domain of the LDLR. This also requires the presence of the C-terminal Cys/His-rich domain, its binding to the secreted cytosolic cyclase associated protein 1, and possibly another membrane-bound "protein X". Curiously, in PCSK9-deficient mice, an alternative to the downregulation of the surface levels of the LDLR by PCSK9 is taking place in the liver of female mice in a 17β-estradiol-dependent manner by still an unknown mechanism. Recent studies have extended our understanding of the biological functions of PCSK9, namely its implication in septic shock, vascular inflammation, viral infections (Dengue; SARS-CoV-2) or immune checkpoint modulation in cancer via the regulation of the cell surface levels of the T-cell receptor and MHC-I, which govern the antitumoral activity of CD8+ T cells. Because PCSK9 inhibition may be advantageous in these processes, the availability of injectable safe PCSK9 inhibitors that reduces by 50% to 60% LDLc above the effect of statins is highly valuable. Indeed, injectable PCSK9 monoclonal antibody or small interfering RNA could be added to current immunotherapies in cancer/metastasis.
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Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM, affiliated to the University of Montreal), Montreal, QC, Canada
| | - Annik Prat
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM, affiliated to the University of Montreal), Montreal, QC, Canada
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Huang L, Fung E, Bose S, Popp A, Böser P, Memmott J, Kutskova YA, Miller R, Tarcsa E, Klein C, Veldman GM, Mueller BK, Cui YF. Elezanumab, a clinical stage human monoclonal antibody that selectively targets repulsive guidance molecule A to promote neuroregeneration and neuroprotection in neuronal injury and demyelination models. Neurobiol Dis 2021; 159:105492. [PMID: 34478849 DOI: 10.1016/j.nbd.2021.105492] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/23/2021] [Accepted: 08/26/2021] [Indexed: 10/20/2022] Open
Abstract
Repulsive guidance molecule A (RGMa) is a potent inhibitor of axonal growth and a regulator of neuronal cell death. It is up-regulated following neuronal injury and accumulates in chronic neurodegenerative diseases. Neutralizing RGMa has the potential to promote neuroregeneration and neuroprotection. Previously we reported that a rat anti-N terminal RGMa (N-RGMa) antibody r5F9 and its humanized version h5F9 (ABT-207) promote neuroprotection and neuroregeneration in preclinical neurodegenerative disease models. However, due to its cross-reactivity to RGMc/hemojuvelin, ABT-207 causes iron accumulation in vivo, which could present a safety liability. Here we report the generation and characterization of a novel RGMa-selective anti-N-RGMa antibody elezanumab, which is currently under Phase 2 clinical evaluation in multiple disease indications. Elezanumab, a human monoclonal antibody generated by in vitro PROfusion mRNA display technology, competes with ABT-207 in binding to N-RGMa but lacks RGMc cross-reactivity with no impact on iron metabolism. It neutralizes repulsive activity of soluble RGMa in vitro and blocks membrane RGMa mediated BMP signaling. In the optic nerve crush and optic neuritis models, elezanumab promotes axonal regeneration and prevents retinal nerve fiber layer degeneration. In the spinal targeted experimental autoimmune encephalomyelitis (EAE) model, elezanumab promotes axonal regeneration and remyelination, decreases inflammatory lesion area and improves functional recovery. Finally, in the mouse cuprizone model, elezanumab reduces demyelination, which is consistent with its inhibitory effect on BMP signaling. Taken together, these preclinical data demonstrate that elezanumab has neuroregenerative and neuroprotective activities without impact on iron metabolism, thus providing a compelling rationale for its clinical development in neurodegenerative diseases.
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Affiliation(s)
- Lili Huang
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA.
| | - Emma Fung
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA.
| | - Sahana Bose
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA.
| | - Andreas Popp
- AbbVie Deutschland GmbH & Co. KG, Knollstrasse, 67061, Ludwigshafen 67061, Germany.
| | - Preethne Böser
- AbbVie Deutschland GmbH & Co. KG, Knollstrasse, 67061, Ludwigshafen 67061, Germany.
| | - John Memmott
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA.
| | - Yuliya A Kutskova
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA.
| | - Renee Miller
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA.
| | - Edit Tarcsa
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA.
| | - Corinna Klein
- AbbVie Deutschland GmbH & Co. KG, Knollstrasse, 67061, Ludwigshafen 67061, Germany.
| | | | - Bernhard K Mueller
- AbbVie Deutschland GmbH & Co. KG, Knollstrasse, 67061, Ludwigshafen 67061, Germany.
| | - Yi-Fang Cui
- AbbVie Deutschland GmbH & Co. KG, Knollstrasse, 67061, Ludwigshafen 67061, Germany.
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10
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Roy A, Pathak Z, Kumar H. Strategies to neutralize RhoA/ROCK pathway after spinal cord injury. Exp Neurol 2021; 343:113794. [PMID: 34166685 DOI: 10.1016/j.expneurol.2021.113794] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/01/2021] [Accepted: 06/19/2021] [Indexed: 01/22/2023]
Abstract
Regeneration is bungled following CNS injuries, including spinal cord injury (SCI). Inherent decay of permissive conditions restricts the regrowth of the mature CNS after an injury. Hypertrophic scarring, insignificant intrinsic axon-growth activity, and axon-growth inhibitory molecules such as myelin inhibitors and scar inhibitors constitute a significant hindrance to spinal cord repair. Besides these molecules, a combined absence of various mechanisms responsible for axonal regeneration is the main reason behind the dereliction of the adult CNS to regenerate. The neutralization of specific inhibitors/proteins by stymieing antibodies or encouraging enzymatic degradation results in improved axon regeneration. Previous efforts to induce regeneration after SCI have stimulated axonal development in or near lesion sites, but not beyond them. Several pathways are responsible for the axonal growth obstruction after a CNS injury, including SCI. Herein, we summarize the axonal, glial, and intrinsic factor which impedes the regeneration. We have also discussed the methods to stabilize microtubules and through this to maintain the proper cytoskeletal dynamics of growth cone as disorganized microtubules lead to the failure of axonal regeneration. Moreover, we primarily focus on diverse inhibitors of axonal growth and molecular approaches to counteract them and their downstream intracellular signaling through the RhoA/ROCK pathway.
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Affiliation(s)
- Abhishek Roy
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat, India
| | - Zarna Pathak
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat, India
| | - Hemant Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, Gujarat, India.
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Robinson RA, Griffiths SC, van de Haar LL, Malinauskas T, van Battum EY, Zelina P, Schwab RA, Karia D, Malinauskaite L, Brignani S, van den Munkhof MH, Düdükcü Ö, De Ruiter AA, Van den Heuvel DMA, Bishop B, Elegheert J, Aricescu AR, Pasterkamp RJ, Siebold C. Simultaneous binding of Guidance Cues NET1 and RGM blocks extracellular NEO1 signaling. Cell 2021; 184:2103-2120.e31. [PMID: 33740419 PMCID: PMC8063088 DOI: 10.1016/j.cell.2021.02.045] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 01/15/2021] [Accepted: 02/22/2021] [Indexed: 12/13/2022]
Abstract
During cell migration or differentiation, cell surface receptors are simultaneously exposed to different ligands. However, it is often unclear how these extracellular signals are integrated. Neogenin (NEO1) acts as an attractive guidance receptor when the Netrin-1 (NET1) ligand binds, but it mediates repulsion via repulsive guidance molecule (RGM) ligands. Here, we show that signal integration occurs through the formation of a ternary NEO1-NET1-RGM complex, which triggers reciprocal silencing of downstream signaling. Our NEO1-NET1-RGM structures reveal a "trimer-of-trimers" super-assembly, which exists in the cell membrane. Super-assembly formation results in inhibition of RGMA-NEO1-mediated growth cone collapse and RGMA- or NET1-NEO1-mediated neuron migration, by preventing formation of signaling-compatible RGM-NEO1 complexes and NET1-induced NEO1 ectodomain clustering. These results illustrate how simultaneous binding of ligands with opposing functions, to a single receptor, does not lead to competition for binding, but to formation of a super-complex that diminishes their functional outputs.
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Affiliation(s)
- Ross A Robinson
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Samuel C Griffiths
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lieke L van de Haar
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Eljo Y van Battum
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Pavol Zelina
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Rebekka A Schwab
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Dimple Karia
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lina Malinauskaite
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sara Brignani
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Marleen H van den Munkhof
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Özge Düdükcü
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Anna A De Ruiter
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Dianne M A Van den Heuvel
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Benjamin Bishop
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Jonathan Elegheert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - A Radu Aricescu
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK; MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands.
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
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12
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Mothe AJ, Coelho M, Huang L, Monnier PP, Cui YF, Mueller BK, Jacobson PB, Tator CH. Delayed administration of the human anti-RGMa monoclonal antibody elezanumab promotes functional recovery including spontaneous voiding after spinal cord injury in rats. Neurobiol Dis 2020; 143:104995. [PMID: 32590037 DOI: 10.1016/j.nbd.2020.104995] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/20/2020] [Accepted: 06/20/2020] [Indexed: 10/24/2022] Open
Abstract
Spinal cord injury (SCI) often results in permanent functional loss due to a series of degenerative events including cell death, axonal damage, and the upregulation of inhibitory proteins that impede regeneration. Repulsive Guidance Molecule A (RGMa) is a potent inhibitor of axonal growth that is rapidly upregulated following injury in both the rodent and human central nervous system (CNS). Previously, we showed that monoclonal antibodies that specifically block inhibitory RGMa signaling promote neuroprotective and regenerative effects when administered acutely in a clinically relevant rat model of thoracic SCI. However, it is unknown whether systemic administration of RGMa blocking antibodies are effective for SCI after delayed administration. Here, we administered elezanumab, a human monoclonal antibody targeting RGMa, intravenously either acutely or at 3 h or 24 h following thoracic clip impact-compression SCI. Rats treated with elezanumab acutely and at 3 h post-injury showed improvements in overground locomotion and fine motor function and gait. Rats treated 24 h post-SCI trended towards better recovery demonstrating significantly greater stride length and swing speed. Treated rats also showed greater tissue preservation with reduced lesion areas. As seen with acute treatment, delayed administration of elezanumab at 3 h post-SCI also increased perilesional neuronal sparing and serotonergic and corticospinal axonal plasticity. In addition, all elezanumab treated rats showed earlier spontaneous voiding ability and less post-trauma bladder wall hypertrophy. Together, our data demonstrate the therapeutic efficacy of delayed systemic administration of elezanumab in a rat model of SCI, and uncovers a new role for RGMa inhibition in bladder recovery following SCI.
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Affiliation(s)
- Andrea J Mothe
- Krembil Brain Institute, Toronto Western Hospital, University Health Network, Toronto, ON M5T 0S8, Canada.
| | - Marlon Coelho
- Krembil Brain Institute, Toronto Western Hospital, University Health Network, Toronto, ON M5T 0S8, Canada
| | - Lili Huang
- AbbVie Bioresearch Center, Worcester, MA 01605, USA
| | - Philippe P Monnier
- Krembil Brain Institute, Toronto Western Hospital, University Health Network, Toronto, ON M5T 0S8, Canada; Department of Ophthalmology and Vision Science, University of Toronto, Toronto, ON M5S 3H6, Canada
| | - Yi-Fang Cui
- Neuroscience Research, AbbVie Deutschland GmbH & Co. KG, Knollstrasse, Ludwigshafen 67061, Germany
| | - Bernhard K Mueller
- Neuroscience Research, AbbVie Deutschland GmbH & Co. KG, Knollstrasse, Ludwigshafen 67061, Germany
| | - Peer B Jacobson
- Integrated Sciences and Technology, AbbVie, North Chicago, IL 60064-6099, USA
| | - Charles H Tator
- Krembil Brain Institute, Toronto Western Hospital, University Health Network, Toronto, ON M5T 0S8, Canada; Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, ON M5T 2S8, Canada.
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13
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Harada H, Charish J, Monnier PP. Emerging evidence for cell-autonomous axon guidance. Dev Growth Differ 2020; 62:391-397. [PMID: 32279322 DOI: 10.1111/dgd.12666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 03/31/2020] [Accepted: 04/03/2020] [Indexed: 11/28/2022]
Abstract
Current models of axon guidance within the central nervous system (CNS) involve the presentation of environmental cues to navigating growth cones. The surrounding and target tissues present a variety of ligands that either restrict or promote growth, thus providing pathfinding instructions to developing axons. Recent findings show that RGMb, a GPI anchored extracellular protein present on retinal ganglion cells, down-regulates Wnt3a signaling by lowering LRP5 levels at the membrane surface. When RGMb is phosphorylated by the extracellular tyrosine kinase VLK, phosphorylated RGMb (p-RGMb) is internalized and carries LRP5 towards intracellular compartments. In the eye, a dorsal-high ventral-low gradient of VLK generates a dorsal-low ventral-high gradient of LRP5 that modulates Wnt3a signaling. These molecules, which are all expressed by individual RGCs, generate Wnt-signal gradients along the dorso-ventral axis of the retina, resulting in differential axon growth which in turn regulates proper retino-tectal/collicular map formation. This pathway represents a regulatory mechanism whereby extracellular phosphorylation generates what may be the first example of a unique self-guiding mechanism that affects neuronal-target connections independent of paracrine signals from the surrounding target tissue.
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Affiliation(s)
- Hidekiyo Harada
- Vision Division, Krembil Research Institute, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Jason Charish
- Vision Division, Krembil Research Institute, Krembil Discovery Tower, Toronto, Ontario, Canada
| | - Philippe P Monnier
- Vision Division, Krembil Research Institute, Krembil Discovery Tower, Toronto, Ontario, Canada.,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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14
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Isaksen TJ, Fujita Y, Yamashita T. Repulsive Guidance Molecule A Suppresses Adult Neurogenesis. Stem Cell Reports 2020; 14:677-691. [PMID: 32243839 PMCID: PMC7160374 DOI: 10.1016/j.stemcr.2020.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/03/2020] [Accepted: 03/03/2020] [Indexed: 01/17/2023] Open
Abstract
Repulsive guidance molecule A (RGMa) is a glycosylphosphatidylinositol-anchored glycoprotein that exhibits repulsive neurite guidance and regulates neuronal differentiation and survival during brain development. However, the function of RGMa in the adult brain is unknown. Here, we show that RGMa is expressed in the adult hippocampus and provide evidence that RGMa signaling suppresses adult neurogenesis. Knockdown of RGMa in the dentate gyrus increased the number of surviving newborn neurons; however, these cells failed to properly migrate into the granular cell layer. In vitro, RGMa stimulation of adult neural stem cells suppressed neurite outgrowth of newborn neurons, which could be prevented by knockdown of the multifunctional receptor neogenin, as well as pharmacological inhibition of the downstream target Rho-associated protein kinase. These findings present a function for RGMa in the adult brain and add to the intricate molecular network that regulates adult brain plasticity. RGMa suppress survival and growth of newborn neurons in the adult dentate gyrus RGMa signaling depends on neogenin for the regulation of adult neurogenesis RGMa induces RhoA/ROCK activation in adult neuronal stem cells
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Affiliation(s)
- Toke Jost Isaksen
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuki Fujita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Graduate School of Frontier Bioscience, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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15
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Zhang Y, Wang X, Cheng J, Lin Y, Yang L, Cao Z, Yang Y. Changes of fractional anisotropy and RGMa in crossed cerebellar diaschisis induced by middle cerebral artery occlusion. Exp Ther Med 2019; 18:3595-3602. [PMID: 31602236 DOI: 10.3892/etm.2019.7986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Accepted: 07/09/2018] [Indexed: 01/18/2023] Open
Abstract
Crossed cerebellar diaschisis (CCD) is the phenomenon of hypoperfusion and hypometabolism of the contralateral cerebellar hemisphere caused by dysfunction of the associated supratentorial region. The aim of the present study was to analyze the changes in fractional anisotropy (FA) in CCD induced by middle cerebral artery occlusion (MCAO) using magnetic resonance-diffusion tensor imaging (MR-DTI). Furthermore, the role of repulsive guidance molecule a (RGMa) in CCD was assessed by measuring RGMa expression using histochemical analysis. In the present study, the cerebellar hemisphere was serially scanned with T2-weighted, serial diffusion-weighted and diffusion tensor (DT) imaging using a 3.0T GE Signa HDxt Scanner to analyze the changes in FA over 72 h. Subsequently, immunohistochemistry analyses of the corresponding cerebellar hemisphere sections were performed to assess the expression of RGMa. Results indicated that FA of both sides of the cerebellar hemisphere, particularly that of the contralateral cerebellar hemisphere (right side) derived from DTI, was reduced during the 72-h time period following MCAO, and the decrease was maximal and statistically significant at 12 h (P<0.05). Immunohistochemistry analysis revealed a significant increase in the expression of RGMa protein in the affected region of the contralateral cerebellar hemisphere (right side) at 24 h following MCAO injury (P<0.05). Furthermore, the expression of RGMa and FA was negatively correlated in MCAO (P<0.05). The results suggest that MR-DTI is an important assessment to evaluate changes of FA in CCD induced by MCAO. Furthermore, the present results suggest that RGMa, which was negatively correlated with FA in MCAO rats, may serve an important role in CCD.
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Affiliation(s)
- Yong Zhang
- Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Xiao Wang
- Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Jingliang Cheng
- Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Yanan Lin
- Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Lu Yang
- Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Zhenghao Cao
- Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Yunjun Yang
- Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
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16
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Rgma-Induced Neo1 Proteolysis Promotes Neural Tube Morphogenesis. J Neurosci 2019; 39:7465-7484. [PMID: 31399534 DOI: 10.1523/jneurosci.3262-18.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 07/01/2019] [Accepted: 07/31/2019] [Indexed: 01/02/2023] Open
Abstract
Neuroepithelial cell (NEC) elongation is one of several key cell behaviors that mediate the tissue-level morphogenetic movements that shape the neural tube (NT), the precursor of the brain and spinal cord. However, the upstream signals that promote NEC elongation have been difficult to tease apart from those regulating apico-basal polarity and hingepoint formation, due to their confounding interdependence. The Repulsive Guidance Molecule a (Rgma)/Neogenin 1 (Neo1) signaling pathway plays a conserved role in NT formation (neurulation) and is reported to regulate both NEC elongation and apico-basal polarity, through signal transduction events that have not been identified. We examine here the role of Rgma/Neo1 signaling in zebrafish (sex unknown), an organism that does not use hingepoints to shape its hindbrain, thereby enabling a direct assessment of the role of this pathway in NEC elongation. We confirm that Rgma/Neo1 signaling is required for microtubule-mediated NEC elongation, and demonstrate via cell transplantation that Neo1 functions cell autonomously to promote elongation. However, in contrast to previous findings, our data do not support a role for this pathway in establishing apical junctional complexes. Last, we provide evidence that Rgma promotes Neo1 glycosylation and intramembrane proteolysis, resulting in the production of a transient, nuclear intracellular fragment (NeoICD). Partial rescue of Neo1a and Rgma knockdown embryos by overexpressing neoICD suggests that this proteolytic cleavage is essential for neurulation. Based on these observations, we propose that RGMA-induced NEO1 proteolysis orchestrates NT morphogenesis by promoting NEC elongation independently of the establishment of apical junctional complexes.SIGNIFICANCE STATEMENT The neural tube, the CNS precursor, is shaped during neurulation. Neural tube defects occur frequently, yet underlying genetic risk factors are poorly understood. Neuroepithelial cell (NEC) elongation is essential for proper completion of neurulation. Thus, connecting NEC elongation with the molecular pathways that control this process is expected to reveal novel neural tube defect risk factors and increase our understanding of NT development. Effectors of cell elongation include microtubules and microtubule-associated proteins; however, upstream regulators remain controversial due to the confounding interdependence of cell elongation and establishment of apico-basal polarity. Here, we reveal that Rgma-Neo1 signaling controls NEC elongation independently of the establishment of apical junctional complexes and identify Rgma-induced Neo1 proteolytic cleavage as a key upstream signaling event.
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17
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Cheng Z, Zhou H, Sherva R, Farrer LA, Kranzler HR, Gelernter J. Genome-wide Association Study Identifies a Regulatory Variant of RGMA Associated With Opioid Dependence in European Americans. Biol Psychiatry 2018; 84:762-770. [PMID: 29478698 PMCID: PMC6041180 DOI: 10.1016/j.biopsych.2017.12.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 12/22/2017] [Accepted: 12/30/2017] [Indexed: 01/07/2023]
Abstract
BACKGROUND Opioid dependence (OD) is at epidemic levels in the United States. Genetic studies can provide insight into its biology. METHODS We completed an OD genome-wide association study in 3058 opioid-exposed European Americans, 1290 of whom met criteria for a DSM-IV diagnosis of OD. Analysis used DSM-IV criterion count. RESULTS By meta-analysis of four cohorts, Yale-Penn 1 (n = 1388), Yale-Penn 2 (n = 996), Yale-Penn 3 (n = 98), and SAGE (Study of Addiction: Genetics and Environment) (n = 576), we identified a variant on chromosome 15, rs12442183, near RGMA, associated with OD (p = 1.3 × 10-8). The association was also genome-wide significant in Yale-Penn 1 taken individually and nominally significant in two of the other three samples. The finding was further supported in a meta-analysis of all available opioid-exposed African Americans (n = 2014 [1106 meeting DSM-IV OD criteria]; p = 3.0 × 10-3) from three cohorts; there was nominal significance in two of these samples. Thus, of seven subsamples examined in two populations, one was genome-wide significant, and four of six were nominally (or nearly) significant. RGMA encodes repulsive guidance molecule A, which is a central nervous system axon guidance protein. Risk allele rs12442183*T was correlated with higher expression of a specific RGMA transcript variant in frontal cortex (p = 2 × 10-3). After chronic morphine injection, the homologous mouse gene (Rgma) was upregulated in C57BL/6J striatum. Coexpression analysis of 1301 brain samples revealed that RGMA messenger RNA expression was associated with that of four genes implicated in other psychiatric disorders, including GRIN1. CONCLUSIONS This is the first study to demonstrate an association of RGMA with OD. It provides a new lead into our understanding of OD pathophysiology.
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Affiliation(s)
- Zhongshan Cheng
- Division of Human Genetics, Department of Psychiatry, Yale University School of Medicine, New Haven, Massachusetts; VA Connecticut Healthcare Center, West Haven, Massachusetts
| | - Hang Zhou
- Division of Human Genetics, Department of Psychiatry, Yale University School of Medicine, New Haven, Massachusetts; VA Connecticut Healthcare Center, West Haven, Massachusetts
| | - Richard Sherva
- Departments of Neurology, Ophthalmology, Genetics & Genomics, Epidemiology, and Biostatistics, Boston University School of Medicine and School Public Health, Boston, Massachusetts
| | - Lindsay A Farrer
- Departments of Neurology, Ophthalmology, Genetics & Genomics, Epidemiology, and Biostatistics, Boston University School of Medicine and School Public Health, Boston, Massachusetts
| | - Henry R Kranzler
- Center for Studies of Addiction, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania; Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, Pennsylvania
| | - Joel Gelernter
- Division of Human Genetics, Department of Psychiatry, Yale University School of Medicine, New Haven, Massachusetts; Departments of Genetics and Neuroscience, Yale University School of Medicine, New Haven, Massachusetts; VA Connecticut Healthcare Center, West Haven, Massachusetts.
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18
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Balashova OA, Visina O, Borodinsky LN. Folate action in nervous system development and disease. Dev Neurobiol 2018; 78:391-402. [PMID: 29380544 DOI: 10.1002/dneu.22579] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 01/24/2018] [Accepted: 01/24/2018] [Indexed: 01/04/2023]
Abstract
The vitamin folic acid has been recognized as a crucial environmental factor for nervous system development. From the early fetal stages of the formation of the presumptive spinal cord and brain to the maturation and maintenance of the nervous system during infancy and childhood, folate levels and its supplementation have been considered influential in the clinical outcome of infants and children affected by neurological diseases. Despite the vast epidemiological information recorded on folate function and neural tube defects, neural development and neurodegenerative diseases, the mechanisms of folate action in the developing neural tissue have remained elusive. Here we compiled studies that argue for a unique role for folate in nervous system development and function and its consequences to neural disease and repair. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 78: 391-402, 2018.
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Affiliation(s)
- Olga A Balashova
- Department of Physiology & Membrane Biology and Institute for Pediatric Regenerative Medicine, Shriners Hospital for Children, University of California Davis School of Medicine, Sacramento, California
| | - Olesya Visina
- Department of Physiology & Membrane Biology and Institute for Pediatric Regenerative Medicine, Shriners Hospital for Children, University of California Davis School of Medicine, Sacramento, California
| | - Laura N Borodinsky
- Department of Physiology & Membrane Biology and Institute for Pediatric Regenerative Medicine, Shriners Hospital for Children, University of California Davis School of Medicine, Sacramento, California
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19
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RGMa mediates reactive astrogliosis and glial scar formation through TGFβ1/Smad2/3 signaling after stroke. Cell Death Differ 2018; 25:1503-1516. [PMID: 29396549 PMCID: PMC6113216 DOI: 10.1038/s41418-018-0058-y] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 12/22/2017] [Accepted: 12/27/2017] [Indexed: 01/11/2023] Open
Abstract
In response to stroke, astrocytes become reactive astrogliosis and are a major component of a glial scar. This results in the formation of both a physical and chemical (production of chondroitin sulfate proteoglycans) barrier, which prevent neurite regeneration that, in turn, interferes with functional recovery. However, the mechanisms of reactive astrogliosis and glial scar formation are poorly understood. In this work, we hypothesized that repulsive guidance molecule a (RGMa) regulate reactive astrogliosis and glial scar formation. We first found that RGMa was strongly expressed by reactive astrocytes in the glial scar in a rat model of middle cerebral artery occlusion/reperfusion. Genetic or pharmacologic inhibition of RGMa in vivo resulted in a strong reduction of reactive astrogliosis and glial scarring as well as in a pronounced improvement in functional recovery. Furthermore, we showed that transforming growth factor β1 (TGFβ1) stimulated RGMa expression through TGFβ1 receptor activin-like kinase 5 (ALK5) in primary cultured astrocytes. Knockdown of RGMa abrogated key steps of reactive astrogliosis and glial scar formation induced by TGFβ1, including cellular hypertrophy, glial fibrillary acidic protein upregulation, cell migration, and CSPGs secretion. Finally, we demonstrated that RGMa co-immunoprecipitated with ALK5 and Smad2/3. TGFβ1-induced ALK5-Smad2/3 interaction and subsequent phosphorylation of Smad2/3 were impaired by RGMa knockdown. Taken together, we identified that after stroke, RGMa promotes reactive astrogliosis and glial scar formation by forming a complex with ALK5 and Smad2/3 to promote ALK5-Smad2/3 interaction to facilitate TGFβ1/Smad2/3 signaling, thereby inhibiting neurological functional recovery. RGMa may be a new therapeutic target for stroke.
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20
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Nickel J, Ten Dijke P, Mueller TD. TGF-β family co-receptor function and signaling. Acta Biochim Biophys Sin (Shanghai) 2018; 50:12-36. [PMID: 29293886 DOI: 10.1093/abbs/gmx126] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 11/08/2017] [Indexed: 01/04/2023] Open
Abstract
Transforming growth factor-β (TGF-β) family members, which include TGF-βs, activins and bone morphogenetic proteins, are pleiotropic cytokines that elicit cell type-specific effects in a highly context-dependent manner in many different tissues. These secreted protein ligands signal via single-transmembrane Type I and Type II serine/threonine kinase receptors and intracellular SMAD transcription factors. Deregulation in signaling has been implicated in a broad array of diseases, and implicate the need for intricate fine tuning in cellular signaling responses. One important emerging mechanism by which TGF-β family receptor signaling intensity, duration, specificity and diversity are regulated and/or mediated is through cell surface co-receptors. Here, we provide an overview of the co-receptors that have been identified for TGF-β family members. While some appear to be specific to TGF-β family members, others are shared with other pathways and provide possible ways for signal integration. This review focuses on novel functions of TGF-β family co-receptors, which continue to be discovered.
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Affiliation(s)
- Joachim Nickel
- Universitätsklinikum Würzburg, Lehrstuhl für Tissue Engineering und Regenerative Medizin und Fraunhofer Institut für Silicatforschung (ISC), Translationszentrum "Regenerative Therapien", Röntgenring 11, D-97070 Würzburg, Germany
| | - Peter Ten Dijke
- Department of Molecular and Cell Biology and Cancer Genomics Centre Netherlands, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, The Netherlands
| | - Thomas D Mueller
- Lehrstuhl für molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs Institut für Biowissenschaften, Universität Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
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21
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Wang Y, Zhang R, Xing X, Guo J, Xie F, Zhang G, Qin X. Repulsive guidance molecule a suppresses angiogenesis after ischemia/reperfusion injury of middle cerebral artery occlusion in rats. Neurosci Lett 2017; 662:318-323. [PMID: 29061393 DOI: 10.1016/j.neulet.2017.10.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/26/2017] [Accepted: 10/19/2017] [Indexed: 10/18/2022]
Abstract
Repulsive guidance molecule a (RGMa) has now emerged as a molecule with pleiotropic roles, including repulsion, adhesion, migration and differentiation in the nervous system. In this study, adult male Sprague-Dawley (SD) rats received 90-min middle cerebral artery occlusion (MCAO) to observe RGMa/neogenin expression sites after ischemia/reperfusion injury and changes in angiogenesis after treatment with RNA interference using RGMa-specific recombinant adenovirus rAd5-shRNA-RGMa (rAd-shRGMa). To clarify how RGMa mediates angiogenesis, the RGMa function-blocking peptide six fibronectin type III (6FNIII) was also administered, and corresponding changes in vascular endothelial growth factor (VEGF), angiopoietin-2 (Ang2), angiopoietin-1 (Ang1), and brain derived neurotrophic factor (BDNF) were determined by western blotting. Both RGMa and its receptor neogenin were expressed in neurons and vessel endothelial cells after ischemia/reperfusion injury, and angiogenesis, coupled with functional recovery, was enhanced after RNA interference against RGMa compared with the vehicle groups. VEGF, Ang2, Ang1 and BDNF expression levels were significantly increased after intervention with rAd-shRGMa or 6FNIII. Thus, RGMa might suppress angiogenesis via VEGF, Ang2, Ang1 and BDNF after cerebral ischemia/reperfusion injury, which has therapeutic potential by reducing these endogenous detrimental mechanisms.
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Affiliation(s)
- Yu Wang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Rongrong Zhang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Xiangfeng Xing
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Jia Guo
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Fei Xie
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Gang Zhang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Xinyue Qin
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
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Rapti G, Li C, Shan A, Lu Y, Shaham S. Glia initiate brain assembly through noncanonical Chimaerin-Furin axon guidance in C. elegans. Nat Neurosci 2017; 20:1350-1360. [PMID: 28846083 PMCID: PMC5614858 DOI: 10.1038/nn.4630] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/19/2017] [Indexed: 01/08/2023]
Abstract
Brain assembly is hypothesized to begin when pioneer axons extend over non-neuronal cells, forming tracts guiding follower axons. Yet pioneer-neuron identities, their guidance substrates, and their interactions are not well understood. Here, using time-lapse embryonic imaging, genetics, protein-interaction, and functional studies, we uncover the early events of C. elegans brain assembly. We demonstrate that C. elegans glia are key for assembly initiation, guiding pioneer and follower axons using distinct signals. Pioneer sublateral neurons, with unique growth properties, anatomy, and innervation, cooperate with glia to mediate follower-axon guidance. We further identify a Chimaerin (CHIN-1)- Furin (KPC-1) double-mutant that severely disrupts assembly. CHIN-1 and KPC-1 function noncanonically, in glia and pioneer neurons, for guidance-cue trafficking. We exploit this bottleneck to define roles for glial Netrin and Semaphorin in pioneer- and follower-axon guidance, respectively, and for glial and pioneer-neuron Flamingo (CELSR) in follower-axon navigation. Taken together, our studies reveal previously undescribed glial roles in pioneer-axon guidance, suggesting conserved principles of brain assembly.
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Affiliation(s)
- Georgia Rapti
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Chang Li
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
- These authors contributed equally to this work
| | - Alan Shan
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
- These authors contributed equally to this work
| | - Yun Lu
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
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23
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Kam JWK, Dumontier E, Baim C, Brignall AC, Mendes da Silva D, Cowan M, Kennedy TE, Cloutier JF. RGMB and neogenin control cell differentiation in the developing olfactory epithelium. Development 2017; 143:1534-46. [PMID: 27143755 DOI: 10.1242/dev.118638] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 02/29/2016] [Indexed: 12/25/2022]
Abstract
Cellular interactions are key for the differentiation of distinct cell types within developing epithelia, yet the molecular mechanisms engaged in these interactions remain poorly understood. In the developing olfactory epithelium (OE), neural stem/progenitor cells give rise to odorant-detecting olfactory receptor neurons (ORNs) and glial-like sustentacular (SUS) cells. Here, we show in mice that the transmembrane receptor neogenin (NEO1) and its membrane-bound ligand RGMB control the balance of neurons and glial cells produced in the OE. In this layered epithelium, neogenin is expressed in progenitor cells, while RGMB is restricted to adjacent newly born ORNs. Ablation of Rgmb via gene-targeting increases the number of dividing progenitor cells in the OE and leads to supernumerary SUS cells. Neogenin loss-of-function phenocopies these effects observed in Rgmb(-/-) mice, supporting the proposal that RGMB-neogenin signaling regulates progenitor cell numbers and SUS cell production. Interestingly, Neo1(-/-) mice also exhibit increased apoptosis of ORNs, implicating additional ligands in the neogenin-dependent survival of ORNs. Thus, our results indicate that RGMB-neogenin-mediated cell-cell interactions between newly born neurons and progenitor cells control the ratio of glia and neurons produced in the OE.
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Affiliation(s)
- Joseph Wai Keung Kam
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - Emilie Dumontier
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - Christopher Baim
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - Alexandra C Brignall
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4
| | - David Mendes da Silva
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Center for Neuroscience and Cell Biology and Department of Life Sciences, University of Coimbra, Rua Larga, Coimbra 3004-517, Portugal
| | - Mitra Cowan
- Centre de Recherches du Centre Hospitalier de l'Université de Montréal, 900 rue Saint-Denis, Montréal, Canada H2X 0A9
| | - Timothy E Kennedy
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Anatomy and Cell Biology, McGill University, 3640 University, Montréal, Québec, Canada H3A 0C7
| | - Jean-François Cloutier
- Montreal Neurological Institute, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Neurology and Neurosurgery, McGill University, 3801 University, Montréal, Québec, Canada H3A 2B4 Department of Anatomy and Cell Biology, McGill University, 3640 University, Montréal, Québec, Canada H3A 0C7
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24
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Mothe AJ, Tassew NG, Shabanzadeh AP, Penheiro R, Vigouroux RJ, Huang L, Grinnell C, Cui YF, Fung E, Monnier PP, Mueller BK, Tator CH. RGMa inhibition with human monoclonal antibodies promotes regeneration, plasticity and repair, and attenuates neuropathic pain after spinal cord injury. Sci Rep 2017; 7:10529. [PMID: 28874746 PMCID: PMC5585220 DOI: 10.1038/s41598-017-10987-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/17/2017] [Indexed: 01/01/2023] Open
Abstract
Traumatic spinal cord injury (SCI) causes a cascade of degenerative events including cell death, axonal damage, and the upregulation of inhibitory molecules which prevent regeneration and limit recovery. Repulsive guidance molecule A (RGMa) is a potent neurite growth inhibitor in the central nervous system, exerting its repulsive activity by binding the Neogenin receptor. Here, we show for the first time that inhibitory RGMa is markedly upregulated in multiple cell types after clinically relevant impact-compression SCI in rats, and importantly, also in the injured human spinal cord. To neutralize inhibitory RGMa, clinically relevant human monoclonal antibodies were systemically administered after acute SCI, and were detected in serum, cerebrospinal fluid, and in the injured tissue. Rats treated with RGMa blocking antibodies showed significantly improved recovery of motor function and gait. Furthermore, RGMa blocking antibodies promoted neuronal survival, and enhanced the plasticity of descending serotonergic pathways and corticospinal tract axonal regeneration. RGMa antibody also attenuated neuropathic pain responses, which was associated with fewer activated microglia and reduced CGRP expression in the dorsal horn caudal to the lesion. These results show the therapeutic potential of the first human RGMa antibody for SCI and uncovers a new role for the RGMa/Neogenin pathway on neuropathic pain.
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Affiliation(s)
- Andrea J Mothe
- Krembil Research Institute, Division of Genetics and Development, Krembil Discovery Tower, Toronto ON, M5T 2S8, Canada. .,Toronto Western Hospital, University Health Network, Toronto ON, M5T 2S8, Canada.
| | - Nardos G Tassew
- Krembil Research Institute, Division of Genetics and Development, Krembil Discovery Tower, Toronto ON, M5T 2S8, Canada
| | - Alirezha P Shabanzadeh
- Krembil Research Institute, Division of Genetics and Development, Krembil Discovery Tower, Toronto ON, M5T 2S8, Canada
| | - Romeo Penheiro
- Krembil Research Institute, Division of Genetics and Development, Krembil Discovery Tower, Toronto ON, M5T 2S8, Canada.,Toronto Western Hospital, University Health Network, Toronto ON, M5T 2S8, Canada
| | - Robin J Vigouroux
- Krembil Research Institute, Division of Genetics and Development, Krembil Discovery Tower, Toronto ON, M5T 2S8, Canada
| | - Lili Huang
- AbbVie Bioresearch Center, Worcester MA, 01605, USA
| | | | - Yi-Fang Cui
- Neuroscience Research, Research and Development, AbbVie Deutschland GmbH & Co. KG, Knollstrasse, Ludwigshafen, 67061, Germany
| | - Emma Fung
- AbbVie Bioresearch Center, Worcester MA, 01605, USA
| | - Philippe P Monnier
- Krembil Research Institute, Division of Genetics and Development, Krembil Discovery Tower, Toronto ON, M5T 2S8, Canada.,Department of Ophthalmology and Vision Science, University of Toronto, Toronto ON, M5S 3H6, Canada
| | - Bernhard K Mueller
- Neuroscience Research, Research and Development, AbbVie Deutschland GmbH & Co. KG, Knollstrasse, Ludwigshafen, 67061, Germany
| | - Charles H Tator
- Krembil Research Institute, Division of Genetics and Development, Krembil Discovery Tower, Toronto ON, M5T 2S8, Canada. .,Toronto Western Hospital, University Health Network, Toronto ON, M5T 2S8, Canada. .,Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto ON, M5S 3H6, Canada.
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25
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Repulsive Guidance Molecule a (RGMa) Induces Neuropathological and Behavioral Changes That Closely Resemble Parkinson's Disease. J Neurosci 2017; 37:9361-9379. [PMID: 28842419 DOI: 10.1523/jneurosci.0084-17.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 07/12/2017] [Accepted: 08/11/2017] [Indexed: 01/06/2023] Open
Abstract
Repulsive guidance molecule member a (RGMa) is a membrane-associated or released guidance molecule that is involved in axon guidance, cell patterning, and cell survival. In our previous work, we showed that RGMa is significantly upregulated in the substantia nigra of patients with Parkinson's disease. Here we demonstrate the expression of RGMa in midbrain human dopaminergic (DA) neurons. To investigate whether RGMa might model aspects of the neuropathology of Parkinson's disease in mouse, we targeted RGMa to adult midbrain dopaminergic neurons using adeno-associated viral vectors. Overexpression of RGMa resulted in a progressive movement disorder, including motor coordination and imbalance, which is typical for a loss of DA release in the striatum. In line with this, RGMa induced selective degeneration of dopaminergic neurons in the substantia nigra (SN) and affected the integrity of the nigrostriatal system. The degeneration of dopaminergic neurons was accompanied by a strong microglia and astrocyte activation. The behavioral, molecular, and anatomical changes induced by RGMa in mice are remarkably similar to the clinical and neuropathological hallmarks of Parkinson's disease. Our data indicate that dysregulation of RGMa plays an important role in the pathology of Parkinson's disease, and antibody-mediated functional interference with RGMa may be a disease modifying treatment option.SIGNIFICANCE STATEMENT Parkinson's disease (PD) is a neurodegenerative disease characterized by severe motor dysfunction due to progressive degeneration of mesencephalic dopaminergic (DA) neurons in the substantia nigra. To date, there is no regenerative treatment available. We previously showed that repulsive guidance molecule member a (RGMa) is upregulated in the substantia nigra of PD patients. Adeno-associated virus-mediated targeting of RGMa to mouse DA neurons showed that overexpression of this repulsive axon guidance and cell patterning cue models the behavioral and neuropathological characteristics of PD in a remarkable way. These findings have implications for therapy development as interfering with the function of this specific axon guidance cue may be beneficial to the survival of DA neurons.
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26
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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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27
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Seidah NG. The PCSK9 revolution and the potential of PCSK9-based therapies to reduce LDL-cholesterol. Glob Cardiol Sci Pract 2017; 2017:e201702. [PMID: 28971102 PMCID: PMC5621713 DOI: 10.21542/gcsp.2017.2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, IRCM; Affiliated to the University of Montreal, 110 Pine Avenue West, Montreal, QC, H2W 1R7Canada
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28
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Abstract
We review the evolution and structure of members of the transforming growth factor β (TGF-β) family, antagonistic or agonistic modulators, and receptors that regulate TGF-β signaling in extracellular environments. The growth factor (GF) domain common to all family members and many of their antagonists evolved from a common cystine knot growth factor (CKGF) domain. The CKGF superfamily comprises six distinct families in primitive metazoans, including the TGF-β and Dan families. Compared with Wnt/Frizzled and Notch/Delta families that also specify body axes, cell fate, tissues, and other families that contain CKGF domains that evolved in parallel, the TGF-β family was the most fruitful in evolution. Complexes between the prodomains and GFs of the TGF-β family suggest a new paradigm for regulating GF release by conversion from closed- to open-arm procomplex conformations. Ternary complexes of the final step in extracellular signaling show how TGF-β GF dimers bind type I and type II receptors on the cell surface, and enable understanding of much of the specificity and promiscuity in extracellular signaling. However, structures suggest that when GFs bind repulsive guidance molecule (RGM) family coreceptors, type I receptors do not bind until reaching an intracellular, membrane-enveloped compartment, blurring the line between extra- and intracellular signaling. Modulator protein structures show how structurally diverse antagonists including follistatins, noggin, and members of the chordin family bind GFs to regulate signaling; complexes with the Dan family remain elusive. Much work is needed to understand how these molecular components assemble to form signaling hubs in extracellular environments in vivo.
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Affiliation(s)
- Andrew P Hinck
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260
| | - Thomas D Mueller
- Department of Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, D-97082 Wuerzburg, Germany
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine and Division of Hematology, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115
- Department of Biological Chemistry and Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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29
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Lee NK, Fok KW, White A, Wilson NH, O'Leary CJ, Cox HL, Michael M, Yap AS, Cooper HM. Neogenin recruitment of the WAVE regulatory complex maintains adherens junction stability and tension. Nat Commun 2016; 7:11082. [PMID: 27029596 PMCID: PMC4821876 DOI: 10.1038/ncomms11082] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 02/19/2016] [Indexed: 02/06/2023] Open
Abstract
To maintain tissue integrity during epithelial morphogenesis, adherens junctions (AJs) must resist the mechanical stresses exerted by dynamic tissue movements. Junctional stability is dependent on actomyosin contractility within the actin ring. Here we describe a novel function for the axon guidance receptor, Neogenin, as a key component of the actin nucleation machinery governing junctional stability. Loss of Neogenin perturbs AJs and attenuates junctional tension. Neogenin promotes actin nucleation at AJs by recruiting the Wave regulatory complex (WRC) and Arp2/3. A direct interaction between the Neogenin WIRS domain and the WRC is crucial for the spatially restricted recruitment of the WRC to the junction. Thus, we provide the first example of a functional WIRS–WRC interaction in epithelia. We further show that Neogenin regulates cadherin recycling at the AJ. In summary, we identify Neogenin as a pivotal component of the AJ, where it influences both cadherin dynamics and junctional tension. The stability of epithelial adherens junctions depends on tension generated by actomyosin contractility. Here Lee et al. describe a novel role for the axon guidance receptor Neogenin in maintaining junctional stability by recruiting actin nucleation machinery to adherens junctions.
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Affiliation(s)
- Natalie K Lee
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ka Wai Fok
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Amanda White
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nicole H Wilson
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Conor J O'Leary
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Hayley L Cox
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Magdalene Michael
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Alpha S Yap
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Helen M Cooper
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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Demicheva E, Cui YF, Bardwell P, Barghorn S, Kron M, Meyer AH, Schmidt M, Gerlach B, Leddy M, Barlow E, O'Connor E, Choi CH, Huang L, Veldman GM, Rus H, Shabanzadeh AP, Tassew NG, Monnier PP, Müller T, Calabresi PA, Schoemaker H, Mueller BK. Targeting repulsive guidance molecule A to promote regeneration and neuroprotection in multiple sclerosis. Cell Rep 2015; 10:1887-98. [PMID: 25801027 DOI: 10.1016/j.celrep.2015.02.048] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 12/01/2014] [Accepted: 02/19/2015] [Indexed: 12/24/2022] Open
Abstract
Repulsive guidance molecule A (RGMa) is a potent inhibitor of neuronal regeneration and a regulator of cell death, and it plays a role in multiple sclerosis (MS). In autopsy material from progressive MS patients, RGMa was found in active and chronic lesions, as well as in normal-appearing gray and white matter, and was expressed by cellular meningeal infiltrates. Levels of soluble RGMa in the cerebrospinal fluid were decreased in progressive MS patients successfully treated with intrathecal corticosteroid triamcinolone acetonide (TCA), showing functional improvements. In vitro, RGMa monoclonal antibodies (mAbs) reversed RGMa-mediated neurite outgrowth inhibition and chemorepulsion. In animal models of CNS damage and MS, RGMa antibody stimulated regeneration and remyelination of damaged nerve fibers, accelerated functional recovery, and protected the retinal nerve fiber layer as measured by clinically relevant optic coherence tomography. These data suggest that targeting RGMa is a promising strategy to improve functional recovery in MS patients.
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31
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Seidah NG. The PCSK9 revolution and the potential of PCSK9-based therapies to reduce LDL-cholesterol. Glob Cardiol Sci Pract 2015. [DOI: 10.5339/gcsp.2015.59] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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32
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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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Shabanzadeh AP, Tassew NG, Szydlowska K, Tymianski M, Banerjee P, Vigouroux RJ, Eubanks JH, Huang L, Geraerts M, Koeberle PD, Mueller BK, Monnier PP. Uncoupling Neogenin association with lipid rafts promotes neuronal survival and functional recovery after stroke. Cell Death Dis 2015; 6:e1744. [PMID: 25950474 PMCID: PMC4669689 DOI: 10.1038/cddis.2015.109] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 02/24/2015] [Accepted: 03/06/2015] [Indexed: 12/31/2022]
Abstract
The dependence receptor Neogenin and its ligand, the repulsive guidance molecule a (RGMa), regulate apoptosis and axonal growth in the developing and the adult central nervous system (CNS). Here, we show that this pathway has also a critical role in neuronal death following stroke, and that providing RGMa to neurons blocks Neogenin-induced death. Interestingly, the Neogenin pro-death function following ischemic insult depends on Neogenin association with lipid rafts. Thus, a peptide that prevents Neogenin association with lipid rafts increased neuronal survival in several in vitro stroke models. In rats, a pro-survival effect was also observed in a model of ocular ischemia, as well as after middle cerebral artery occlusion (MCAO). Treatments that prevented Neogenin association with lipid rafts improved neuronal survival and the complexity of the neuronal network following occlusion of the middle artery. Toward the development of a treatment for stroke, we developed a human anti-RGMa antibody that also prevents Neogenin association with lipid rafts. We show that this antibody also protected CNS tissue from ischemic damage and that its application resulted in a significant functional improvement even when administrated 6 h after artery occlusion. Thus, our results draw attention to the role of Neogenin and lipid rafts as potential targets following stroke.
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Affiliation(s)
- A P Shabanzadeh
- 1] Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada [2] Department of Anatomy, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - N G Tassew
- 1] Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada [2] Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - K Szydlowska
- Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada
| | - M Tymianski
- 1] Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada [2] Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada [3] Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - P Banerjee
- Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada
| | - R J Vigouroux
- 1] Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada [2] Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - J H Eubanks
- 1] Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada [2] Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - L Huang
- AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA
| | - M Geraerts
- Neuroscience Research, Research and Development, AbbVie Deutschland GmbH & CO KG, Knollstrasse, D-67061 Ludwigshafen, Germany
| | - P D Koeberle
- 1] Department of Anatomy, Faculty of Medicine, University of Toronto, Toronto, ON, Canada [2] Department of Ophthalmology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - B K Mueller
- Neuroscience Research, Research and Development, AbbVie Deutschland GmbH & CO KG, Knollstrasse, D-67061 Ludwigshafen, Germany
| | - P P Monnier
- 1] Toronto Western Research Institute, Genetics and Development Division, KDT 8-418, 60 Leonard Street, Toronto, M5T 2S8 ON, Canada [2] Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada [3] Department of Ophthalmology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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Couture F, Kwiatkowska A, Dory YL, Day R. Therapeutic uses of furin and its inhibitors: a patent review. Expert Opin Ther Pat 2015; 25:379-96. [PMID: 25563687 DOI: 10.1517/13543776.2014.1000303] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Since the discovery of furin, numerous reports have studied its role in health and diseases, including cancer, inflammatory and infectious diseases. This interest has led to the development of both large protein- and peptide-based inhibitors aiming to control furin activity to treat these disorders. The most recent advances include the development of potent peptidomimetic furin inhibitors, considerably expanding the field of therapeutic applications. AREA COVERED In this review, the use of furin or its inhibitors for therapeutic conditions is described through the patent literature since 1994. Only compounds with biological efficacy or augmented properties demonstrated within the patent literature or the associated publications concerning their claimed uses are discussed. EXPERT OPINION Considering the diseases that may benefit from furin inhibition, several patents detail the use of the restricted number of furin inhibitors. However, there have been recent reports of new scaffolds, and even the use of furin itself, as a therapeutic agent. Despite considerable evidence of in vivo efficacy, limited confirmation from clinical trials supports or refutes the further use of these compounds in a therapeutic context. The most advanced application is the use of furin knockdown in the generation of an autologous cancer vaccine, which has initiated clinical trials.
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Affiliation(s)
- Frédéric Couture
- Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, Faculté de Médecine et des Sciences de la Santé , 3001 12e Ave. Nord, Sherbrooke, Québec, J1H 5N4 , Canada +1 819 564 5428 ; +1 819 564 5400 ;
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Salzberg Y, Ramirez-Suarez NJ, Bülow HE. The proprotein convertase KPC-1/furin controls branching and self-avoidance of sensory dendrites in Caenorhabditis elegans. PLoS Genet 2014; 10:e1004657. [PMID: 25232734 PMCID: PMC4169376 DOI: 10.1371/journal.pgen.1004657] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/09/2014] [Indexed: 11/18/2022] Open
Abstract
Animals sample their environment through sensory neurons with often elaborately branched endings named dendritic arbors. In a genetic screen for genes involved in the development of the highly arborized somatosensory PVD neuron in C. elegans, we have identified mutations in kpc-1, which encodes the homolog of the proprotein convertase furin. We show that kpc-1/furin is necessary to promote the formation of higher order dendritic branches in PVD and to ensure self-avoidance of sister branches, but is likely not required during maintenance of dendritic arbors. A reporter for kpc-1/furin is expressed in neurons (including PVD) and kpc-1/furin can function cell-autonomously in PVD neurons to control patterning of dendritic arbors. Moreover, we show that kpc-1/furin also regulates the development of other neurons in all major neuronal classes in C. elegans, including aspects of branching and extension of neurites as well as cell positioning. Our data suggest that these developmental functions require proteolytic activity of KPC-1/furin. Recently, the skin-derived MNR-1/menorin and the neural cell adhesion molecule SAX-7/L1CAM have been shown to act as a tripartite complex with the leucine rich transmembrane receptor DMA-1 on PVD mechanosensory to orchestrate the patterning of dendritic branches. Genetic analyses show that kpc-1/furin functions in a pathway with MNR-1/menorin, SAX-7/L1CAM and DMA-1 to control dendritic branch formation and extension of PVD neurons. We propose that KPC-1/furin acts in concert with the ‘menorin’ pathway to control branching and growth of somatosensory dendrites in PVD. Sensory neurons receive input from other neurons or sample their environment through elaborate structures termed dendritic trees. The correct patterning of dendritic trees is crucial for the proper function of the nervous system, and ample evidence points to the involvement of dendritic defects in a wide range of neuropsychiatric diseases. However, we still do not understand fully how this process is regulated at the molecular level. We discovered an important role for the protein-processing enzyme KPC-1/furin in the development of touch-sensitive dendritic trees in the roundworm C. elegans. Animals lacking this enzyme show multiple defects in the size, shape and number of these dendritic branches as well as other neurons. We further show that the gene encoding KPC-1 is expressed widely in the nervous system and that it is required within the branching neuron to exert its function on dendritic growth. Finally, we reveal a genetic connection between KPC-1 function and genes of the menorin pathway, which was recently discovered to also play an essential role in dendrite development. Thus, our findings add new insight into the molecular understanding of dendrite formation.
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Affiliation(s)
- Yehuda Salzberg
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
| | - Nelson J. Ramirez-Suarez
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
| | - Hannes E. Bülow
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
- * E-mail:
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Craig SEL, Brady-Kalnay SM. Regulation of development and cancer by the R2B subfamily of RPTPs and the implications of proteolysis. Semin Cell Dev Biol 2014; 37:108-18. [PMID: 25223585 DOI: 10.1016/j.semcdb.2014.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/04/2014] [Accepted: 09/05/2014] [Indexed: 01/04/2023]
Abstract
The initial cloning of receptor protein tyrosine phosphatases (RPTPs) was met with excitement because of their hypothesized function in counterbalancing receptor tyrosine kinase signaling. In recent years, members of a subfamily of RPTPs with homophilic cell-cell adhesion capabilities, known as the R2B subfamily, have been shown to have functions beyond that of counteracting tyrosine kinase activity, by independently influencing cell signaling in their own right and by regulating cell adhesion. The R2B subfamily is composed of four members: PTPmu (PTPRM), PTPrho (PTPRT), PTPkappa (PTPRK), and PCP-2 (PTPRU). The effects of this small subfamily of RPTPs is far reaching, influencing several developmental processes and cancer. In fact, R2B RPTPs are predicted to be tumor suppressors and are among the most frequently mutated protein tyrosine phosphatases (PTPs) in cancer. Confounding these conclusions are more recent studies suggesting that proteolysis of the full-length R2B RPTPs result in oncogenic extracellular and intracellular protein fragments. This review discusses the current knowledge of the role of R2B RPTPs in development and cancer, with special detail given to the mechanisms and implications that proteolysis has on R2B RPTP function. We also touch upon the concept of exploiting R2B proteolysis to develop cancer imaging tools, and consider the effects of R2B proteolysis on axon guidance, perineural invasion and collective cell migration.
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Affiliation(s)
- Sonya E L Craig
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4960, USA
| | - Susann M Brady-Kalnay
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4960, USA; Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
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Decreased levels of repulsive guidance molecule A in association with beneficial effects of repeated intrathecal triamcinolone acetonide application in progressive multiple sclerosis patients. J Neural Transm (Vienna) 2014; 122:841-8. [PMID: 25209051 DOI: 10.1007/s00702-014-1308-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 09/02/2014] [Indexed: 12/23/2022]
Abstract
Repeated intrathecal application of the sustained release steroid triamcinolone acetonide is beneficial in progressive multiple sclerosis patients. Its putative regenerative effect may involve regulation of the repulsive guidance molecule A synthesis. This protein inhibits axonal regeneration and functional recovery. Objectives were to demonstrate the efficacy of four triamcinolone applications every other day in association with repulsive guidance molecule A levels in cerebrospinal fluid. Clinical evaluation was performed at baseline and on each day after a triamcinolone administration in 25 progressive multiple sclerosis patients. Repulsive guidance molecule A concentrations were determined before each triamcinolone application by western blot analysis with quantification. Clinical scores for multiple sclerosis improved, and the maximum walking distance and speed ameliorated in 17 patients. Repulsive guidance molecule A levels declined in these responders. The remaining patients showed no prompt clinical benefit and no decrease of repulsive guidance molecule A concentrations. Decline of repulsive guidance molecule A may reflect regeneration and functional recovery by triamcinolone in progressive multiple sclerosis patients.
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Tassew NG, Mothe AJ, Shabanzadeh AP, Banerjee P, Koeberle PD, Bremner R, Tator CH, Monnier PP. Modifying lipid rafts promotes regeneration and functional recovery. Cell Rep 2014; 8:1146-59. [PMID: 25127134 DOI: 10.1016/j.celrep.2014.06.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 04/17/2014] [Accepted: 06/10/2014] [Indexed: 10/24/2022] Open
Abstract
Ideal strategies to ameliorate CNS damage should promote both neuronal survival and axon regeneration. The receptor Neogenin promotes neuronal apoptosis. Its ligand prevents death, but the resulting repulsive guidance molecule a (RGMa)-Neogenin interaction also inhibits axonal growth, countering any prosurvival benefits. Here, we explore strategies to inhibit Neogenin, thus simultaneously enhancing survival and regeneration. We show that bone morphogenetic protein (BMP) and RGMa-dependent recruitment of Neogenin into lipid rafts requires an interaction between RGMa and Neogenin subdomains. RGMa or Neogenin peptides that prevent this interaction, BMP inhibition by Noggin, or reduction of membrane cholesterol all block Neogenin raft localization, promote axon outgrowth, and prevent neuronal apoptosis. Blocking Neogenin raft association influences axonal pathfinding, enhances survival in the developing CNS, and promotes survival and regeneration in the injured adult optic nerve and spinal cord. Moreover, lowering cholesterol disrupts rafts and restores locomotor function after spinal cord injury. These data reveal a unified strategy to promote both survival and regeneration in the CNS.
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Affiliation(s)
- Nardos G Tassew
- Toronto Western Research Institute, Genetics and Development Division, Krembil Discovery Tower, KDT-8-418, 60 Leonard Street, Toronto, ON M5T 2S8, Canada; Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Andrea J Mothe
- Toronto Western Research Institute, Genetics and Development Division, Krembil Discovery Tower, KDT-8-418, 60 Leonard Street, Toronto, ON M5T 2S8, Canada
| | - Alireza P Shabanzadeh
- Toronto Western Research Institute, Genetics and Development Division, Krembil Discovery Tower, KDT-8-418, 60 Leonard Street, Toronto, ON M5T 2S8, Canada; Department of Anatomy, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Paromita Banerjee
- Toronto Western Research Institute, Genetics and Development Division, Krembil Discovery Tower, KDT-8-418, 60 Leonard Street, Toronto, ON M5T 2S8, Canada
| | - Paulo D Koeberle
- Department of Anatomy, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Department of Ophthalmology, Faculty of Medicine, 340 College Street, University of Toronto, Toronto, ON M5T 3A9, Canada
| | - Rod Bremner
- Toronto Western Research Institute, Genetics and Development Division, Krembil Discovery Tower, KDT-8-418, 60 Leonard Street, Toronto, ON M5T 2S8, Canada; Department of Ophthalmology, Faculty of Medicine, 340 College Street, University of Toronto, Toronto, ON M5T 3A9, Canada; Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 982 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Charles H Tator
- Toronto Western Research Institute, Genetics and Development Division, Krembil Discovery Tower, KDT-8-418, 60 Leonard Street, Toronto, ON M5T 2S8, Canada
| | - Philippe P Monnier
- Toronto Western Research Institute, Genetics and Development Division, Krembil Discovery Tower, KDT-8-418, 60 Leonard Street, Toronto, ON M5T 2S8, Canada; Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Department of Ophthalmology, Faculty of Medicine, 340 College Street, University of Toronto, Toronto, ON M5T 3A9, Canada.
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O'Leary C, Cole SJ, Langford M, Hewage J, White A, Cooper HM. RGMa regulates cortical interneuron migration and differentiation. PLoS One 2013; 8:e81711. [PMID: 24312340 PMCID: PMC3842424 DOI: 10.1371/journal.pone.0081711] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 10/23/2013] [Indexed: 11/24/2022] Open
Abstract
The etiology of neuropsychiatric disorders, including schizophrenia and autism, has been linked to a failure to establish the intricate neural network comprising excitatory pyramidal and inhibitory interneurons during neocortex development. A large proportion of cortical inhibitory interneurons originate in the medial ganglionic eminence (MGE) of the ventral telencephalon and then migrate through the ventral subventricular zone, across the corticostriatal junction, into the embryonic cortex. Successful navigation of newborn interneurons through the complex environment of the ventral telencephalon is governed by spatiotemporally restricted deployment of both chemorepulsive and chemoattractive guidance cues which work in concert to create a migratory corridor. Despite the expanding list of interneuron guidance cues, cues responsible for preventing interneurons from re-entering the ventricular zone of the ganglionic eminences have not been well characterized. Here we provide evidence that the chemorepulsive axon guidance cue, RGMa (Repulsive Guidance Molecule a), may fulfill this function. The ventricular zone restricted expression of RGMa in the ganglionic eminences and the presence of its receptor, Neogenin, in the ventricular zone and on newborn and maturing MGE-derived interneurons implicates RGMa-Neogenin interactions in interneuron differentiation and migration. Using an in vitro approach, we show that RGMa promotes interneuron differentiation by potentiating neurite outgrowth. In addition, using in vitro explant and migration assays, we provide evidence that RGMa is a repulsive guidance cue for newborn interneurons migrating out of the ganglionic eminence ventricular zone. Intriguingly, the alternative Neogenin ligand, Netrin-1, had no effect on migration. However, we observed complete abrogation of RGMa-induced chemorepulsion when newborn interneurons were simultaneously exposed to RGMa and Netrin-1 gradients, suggesting a novel mechanism for the tight regulation of RGMa-guided interneuron migration. We propose that during peak neurogenesis, repulsive RGMa-Neogenin interactions drive interneurons into the migratory corridor and prevent re-entry into the ventricular zone of the ganglionic eminences.
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Affiliation(s)
- Conor O'Leary
- The University of Queensland, Queensland Brain Institute, Brisbane, Queensland, Australia
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Brugeaud A, Tong M, Luo L, Edge ASB. Inhibition of repulsive guidance molecule, RGMa, increases afferent synapse formation with auditory hair cells. Dev Neurobiol 2013; 74:457-66. [PMID: 24123853 DOI: 10.1002/dneu.22136] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/03/2013] [Accepted: 09/23/2013] [Indexed: 11/12/2022]
Abstract
The peripheral fibers that extend from auditory neurons to hair cells are sensitive to damage, and replacement of the fibers and their afferent synapse with hair cells would be of therapeutic interest. Here, we show that RGMa, a repulsive guidance molecule previously shown to play a role in the development of the chick visual system, is expressed in the developing, newborn, and mature mouse inner ear. The effect of RGMa on synaptogenesis between afferent neurons and hair cells, from which afferent connections had been removed, was assessed. Contact of neural processes with hair cells and elaboration of postsynaptic densities at sites of the ribbon synapse were increased by treatment with a blocking antibody to RGMa, and pruning of auditory fibers to achieve the mature branching pattern of afferent neurons was accelerated. Inhibition by RGMa could thus explain why auditory neurons have a low capacity to regenerate peripheral processes: postnatal spiral ganglion neurons retain the capacity to send out processes that respond to signals for synapse formation, but expression of RGMa postnatally appears to be detrimental to regeneration of afferent hair cell innervation and antagonizes synaptogenesis. Increased synaptogenesis after inhibition of RGMa suggests that manipulation of guidance or inhibitory factors may provide a route to increase formation of new synapses at deafferented hair cells.
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Affiliation(s)
- Aurore Brugeaud
- Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, 02115; Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, 02114
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Schroeder NE, Androwski RJ, Rashid A, Lee H, Lee J, Barr MM. Dauer-specific dendrite arborization in C. elegans is regulated by KPC-1/Furin. Curr Biol 2013; 23:1527-35. [PMID: 23932402 PMCID: PMC4671503 DOI: 10.1016/j.cub.2013.06.058] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 06/04/2013] [Accepted: 06/24/2013] [Indexed: 11/17/2022]
Abstract
BACKGROUND Dendrites often display remarkably complex and diverse morphologies that are influenced by developmental and environmental cues. Neuroplasticity in response to adverse environmental conditions entails both hypertrophy and resorption of dendrites. How dendrites rapidly alter morphology in response to unfavorable environmental conditions is unclear. The nematode Caenorhabditis elegans enters into a stress-resistant dauer larval stage in response to an adverse environment. RESULTS Here we show that the IL2 bipolar sensory neurons undergo dendrite arborization and axon remodeling during dauer development. When dauer larvae are returned to favorable environmental conditions, animals resume reproductive development and IL2 dendritic branches retract, leaving behind remnant branches in postdauer L4 and adult animals. The C. elegans furin homolog KPC-1 is required for dauer IL2 dendritic arborization and dauer-specific nictation behavior. KPC-1 is also necessary for dendritic arborization of PVD and FLP sensory neurons. In mammals, furin is essential, ubiquitously expressed, and associated with numerous pathologies, including neurodegenerative diseases. While broadly expressed in C. elegans neurons and epithelia, KPC-1 acts cell autonomously in IL2 neurons to regulate dauer-specific dendritic arborization and nictation. CONCLUSIONS Neuroplasticity of the C. elegans IL2 sensory neurons provides a paradigm to study stress-induced and reversible dendritic branching, and the role of environmental and developmental cues in this process. The newly discovered role of KPC-1 in dendrite morphogenesis provides insight into the function of proprotein convertases in nervous system development.
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Affiliation(s)
- Nathan E Schroeder
- Department of Genetics and The Human Genetics Institute of New Jersey, Rutgers University, 145 Bevier Road, Piscataway, NJ 08854 USA
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Tian C, Liu J. Repulsive guidance molecules (RGMs) and neogenin in bone morphogenetic protein (BMP) signaling. Mol Reprod Dev 2013; 80:700-17. [PMID: 23740870 DOI: 10.1002/mrd.22199] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 05/28/2013] [Indexed: 02/06/2023]
Abstract
Bone morphogenetic proteins (BMPs) belong to the transforming growth factor-beta (TGFβ) superfamily. BMPs mediate a highly conserved signal transduction cascade through the type-I and type-II serine/threonine kinase receptors and intracellular Smad proteins, which regulate multiple developmental and homeostatic processes. Mutations in this pathway can cause various diseases in humans, such as skeletal disorders, cardiovascular diseases, and various cancers. Multiple levels of regulation, including extracellular regulation, help to ensure proper spatiotemporal control of BMP signaling in the right cellular context. The family of repulsive guidance molecules (RGMs) and the type-I transmembrane protein neogenin, a paralog of DCC (Deleted in Colorectal Cancer), have been implicated in modulating the BMP pathway. In this review, we discuss the properties and functions of RGM proteins and neogenin, focusing on their roles in the modulation of BMP signal transduction.
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Affiliation(s)
- Chenxi Tian
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
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Seidah NG, Sadr MS, Chrétien M, Mbikay M. The multifaceted proprotein convertases: their unique, redundant, complementary, and opposite functions. J Biol Chem 2013; 288:21473-81. [PMID: 23775089 DOI: 10.1074/jbc.r113.481549] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The secretory proprotein convertase (PC) family comprises nine members: PC1/3, PC2, furin, PC4, PC5/6, PACE4, PC7, SKI-1/S1P, and PCSK9. The first seven PCs cleave their substrates at single or paired basic residues, and SKI-1/S1P cleaves its substrates at non-basic residues in the Golgi. PCSK9 cleaves itself once, and the secreted inactive protease escorts specific receptors for lysosomal degradation. It regulates the levels of circulating LDL cholesterol and is considered a major therapeutic target in phase III clinical trials. In vivo, PCs exhibit unique and often essential functions during development and/or in adulthood, but certain convertases also exhibit complementary, redundant, or opposite functions.
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Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM, affiliated with the University of Montreal), Montreal, Quebec H2W 1R7, Canada.
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Abstract
Arenaviruses include lethal human pathogens which pose serious public health threats. So far, no FDA approved vaccines are available against arenavirus infections, and therapeutic options are limited, making the identification of novel drug targets for the development of efficacious therapeutics an urgent need. Arenaviruses are comprised of two RNA genome segments and four proteins, the polymerase L, the envelope glycoprotein GP, the matrix protein Z, and the nucleoprotein NP. A crucial step in the arenavirus life-cycle is the biosynthesis and maturation of the GP precursor (GPC) by cellular signal peptidases and the cellular enzyme Subtilisin Kexin Isozyme-1 (SKI-1)/Site-1 Protease (S1P) yielding a tripartite mature GP complex formed by GP1/GP2 and a stable signal peptide (SSP). GPC cleavage by SKI-1/S1P is crucial for fusion competence and incorporation of mature GP into nascent budding virion particles. In a first part of our review, we cover basic aspects and newer developments in the biosynthesis of arenavirus GP and its molecular interaction with SKI-1/S1P. A second part will then highlight the potential of SKI-1/S1P-mediated processing of arenavirus GPC as a novel target for therapeutic intervention to combat human pathogenic arenaviruses.
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Kee N, Wilson N, Key B, Cooper HM. Netrin-1 is required for efficient neural tube closure. Dev Neurobiol 2012; 73:176-87. [PMID: 22888057 DOI: 10.1002/dneu.22051] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 07/02/2012] [Accepted: 08/08/2012] [Indexed: 12/19/2022]
Abstract
During neural tube formation, neural plate cells migrate from the lateral aspects of the dorsal surface towards the midline. Elevation of the lateral regions of the neural plate produces the neural folds which then migrate to the midline where they fuse at their dorsal tips, generating a closed neural tube comprising an apicobasally polarized neuroepithelium. Our previous study identified a novel role for the axon guidance receptor neogenin in Xenopus neural tube formation. We demonstrated that loss of neogenin impeded neural fold apposition and neural tube closure. This study also revealed that neogenin, via its interaction with its ligand, RGMa, promoted cell-cell adhesion between neural plate cells as the neural folds elevated and between neuroepithelial cells within the neural tube. The second neogenin ligand, netrin-1, has been implicated in cell migration and epithelial morphogenesis. Therefore, we hypothesized that netrin-1 may also act as a ligand for neogenin during neurulation. Here we demonstrate that morpholino knockdown of Xenopus netrin-1 results in delayed neural fold apposition and neural tube closure. We further show that netrin-1 functions in the same pathway as neogenin and RGMa during neurulation. However, contrary to the role of neogenin-RGMa interactions, neogenin-netrin-1 interactions are not required for neural fold elevation or adhesion between neuroepithelial cells. Instead, our data suggest that netrin-1 contributes to the migration of the neural folds towards the midline. We conclude that both neogenin ligands work synergistically to ensure neural tube closure.
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Affiliation(s)
- Nigel Kee
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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48
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Repulsive guidance molecule (RGM) family proteins exhibit differential binding kinetics for bone morphogenetic proteins (BMPs). PLoS One 2012; 7:e46307. [PMID: 23029472 PMCID: PMC3459908 DOI: 10.1371/journal.pone.0046307] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/29/2012] [Indexed: 11/30/2022] Open
Abstract
Bone morphogenetic proteins (BMPs) are members of the transforming growth factor beta superfamily that exert their effects via type I and type II serine threonine kinase receptors and the SMAD intracellular signaling pathway to regulate diverse biologic processes. Recently, we discovered that the repulsive guidance molecule (RGM) family, including RGMA, RGMB, and RGMC/hemojuvelin (HJV), function as co-receptors that enhance cellular responses to BMP ligands. Here, we use surface plasmon resonance to quantitate the binding kinetics of RGM proteins for BMP ligands. We show that among the RGMs, HJV exhibits the highest affinity for BMP6, BMP5, and BMP7 with KD 8.1, 17, and 20 nM respectively, versus 28, 33, and 166 nM for RGMB, and 55, 83, and 63 nM for RGMA. Conversely, RGMB exhibits preferential binding to BMP4 and BMP2 with KD 2.6 and 5.5 nM respectively, versus 4.5 and 9.4 nM for HJV, and 14 and 22 nM for RGMA, while RGMA exhibits the lowest binding affinity for most BMPs tested. Among the BMP ligands, RGMs exhibit the highest relative affinity for BMP4 and the lowest relative affinity for BMP7, while none of the RGMs bind to BMP9. Thus, RGMs exhibit preferential binding for distinct subsets of BMP ligands. The preferential binding of HJV for BMP6 is consistent with the functional role of HJV and BMP6 in regulating systemic iron homeostasis. Our data may help explain the mechanism by which BMPs exert cell-context specific effects via a limited number of type I and type II receptors.
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49
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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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50
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Seidah NG, Prat A. The biology and therapeutic targeting of the proprotein convertases. Nat Rev Drug Discov 2012; 11:367-83. [PMID: 22679642 DOI: 10.1038/nrd3699] [Citation(s) in RCA: 588] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The mammalian proprotein convertases constitute a family of nine secretory serine proteases that are related to bacterial subtilisin and yeast kexin. Seven of these (proprotein convertase 1 (PC1), PC2, furin, PC4, PC5, paired basic amino acid cleaving enzyme 4 (PACE4) and PC7) activate cellular and pathogenic precursor proteins by cleavage at single or paired basic residues, whereas subtilisin kexin isozyme 1 (SKI-1) and proprotein convertase subtilisin kexin 9 (PCSK9) regulate cholesterol and/or lipid homeostasis via cleavage at non-basic residues or through induced degradation of receptors. Proprotein convertases are now considered to be attractive targets for the development of powerful novel therapeutics. In this Review, we summarize the physiological functions and pathological implications of the proprotein convertases, and discuss proposed strategies to control some of their activities, including their therapeutic application and validation in selected disease states.
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Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (affiliated to University of Montreal), 110 Pine Ave West, Montreal, Quebec H2W 1R7, Canada.
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