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Kan YY, Chang YS, Liao WC, Chao TN, Hsieh YL. Roles of Neuronal Protein Kinase Cε on Endoplasmic Reticulum Stress and Autophagic Formation in Diabetic Neuropathy. Mol Neurobiol 2024; 61:2481-2495. [PMID: 37906389 PMCID: PMC11043183 DOI: 10.1007/s12035-023-03716-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 10/14/2023] [Indexed: 11/02/2023]
Abstract
In chronic diabetic neuropathy (DN), the cellular mechanisms of neuropathic pain remain unclear. Protein kinase C epsilon (PKCε) is an intracellular signaling molecule that mediates chronic pain. This paper addresses the long-term upregulated PKCε in DN associated with endoplasmic reticulum (ER) stress and autophagic formation and correlates to chronic neuropathic pain. We found that thermal hyperalgesia and mechanical allodynia course development were associated with PKCε upregulation after DN but not skin denervation. Pathologically, PKCε upregulation was associated with the expression of inositol-requiring enzyme 1α (IRE1α; ER stress-related molecule) and ubiquitin D (UBD), which are involved in the ubiquitin-proteasome system (UPS)-mediated degradation of misfolded proteins under ER stress. Manders coefficient analyses revealed an approximately 50% colocalized ratio for IRE1α(+):PKCε(+) neurons (0.34-0.48 for M1 and 0.40-0.58 for M2 Manders coefficients). The colocalized coefficients of UBD/PKCε increased (M1: 0.33 ± 0.03 vs. 0.77 ± 0.04, p < 0.001; M2: 0.29 ± 0.05 vs. 0.78 ± 0.04; p < 0.001) in the acute DN stage. In addition, the regulatory subunit p85 of phosphoinositide 3-kinase, which is involved in regulating insulin signaling, exhibited similar expression patterns to those of IRE1α and UBD; for example, it had highly colocalized ratios to PKCε. The ultrastructural examination further confirmed that autophagic formation was associated with PKCε upregulation. Furthermore, PKCεv1-2, a PKCε specific inhibitor, reverses neuropathic pain, ER stress, and autophagic formation in DN. This finding suggests PKCε plays an upstream molecule in DN-associated neuropathic pain and neuropathology and could provide a potential therapeutic target.
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Affiliation(s)
- Yu-Yu Kan
- School of Medicine, College of Medicine, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Ying-Shuang Chang
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
| | - Wen-Chieh Liao
- Doctoral Program in Tissue Engineering and Regenerative Medicine, College of Medicine, National Chung Hsing University, Taichung, 40227, Taiwan
- Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Tzu-Ning Chao
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
| | - Yu-Lin Hsieh
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
- School of Post-Baccalaureate Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, 80708, Taiwan.
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Zhao Y, Chang YH, Ren HR, Lou M, Jiang FW, Wang JX, Chen MS, Liu S, Shi YS, Zhu HM, Li JL. Phthalates Induce Neurotoxicity by Disrupting the Mfn2-PERK Axis-Mediated Endoplasmic Reticulum-Mitochondria Interaction. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:7411-7422. [PMID: 38390847 DOI: 10.1021/acs.jafc.3c07752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Di-(2-ethylhexyl) phthalate (DEHP), as the most common phthalate, has been extensively used as a plasticizer to improve the plasticity of agricultural products, which pose severe harm to human health. Mitochondrial dynamics and endoplasmic reticulum (ER) homeostasis are indispensable for maintaining mitochondria-associated ER membrane (MAM) integrity. In this study, we aimed to explore the effect of DEHP on the nervous system and its association with the ER-mitochondria interaction. Here, we showed that DEHP caused morphological changes, motor deficits, cognitive impairments, and blood-brain barrier disruption in the brain. DEHP triggered ER stress, which is mainly mediated by protein kinase R-like endoplasmic reticulum kinase (PERK) signaling. Moreover, DEHP-induced mitofusin-2 (Mfn2) downregulation results in imbalance of the mitochondrial dynamics. Interestingly, DEHP exposure impaired MAMs by inhibiting the Mfn2-PERK interaction. Above all, this study elucidates the disruption of the Mfn2-PERK axis-mediated ER-mitochondria interaction as a phthalate-induced neurotoxicity that could be potentially developed as a novel therapy for neurological diseases.
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Affiliation(s)
- Yi Zhao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, P. R. China
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Yuan-Hang Chang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Hao-Ran Ren
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Ming Lou
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Fu-Wei Jiang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Jia-Xin Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Ming-Shan Chen
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Shuo Liu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Yu-Sheng Shi
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Hong-Mei Zhu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
| | - Jin-Long Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin 150030, P. R. China
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Northeast Agricultural University, Harbin 150030, P. R. China
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Touvier T, Veneri FA, Claessens A, Ferri C, Mastrangelo R, Sorgiati N, Bianchi F, Valenzano S, Del Carro U, Rivellini C, Duong P, Shy ME, Kelly JW, Svaren J, Wiseman RL, D'Antonio M. Activation of XBP1s attenuates disease severity in models of proteotoxic Charcot-Marie-Tooth type 1B. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.31.577760. [PMID: 38352425 PMCID: PMC10862880 DOI: 10.1101/2024.01.31.577760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Mutations in myelin protein zero (MPZ) are generally associated with Charcot-Marie-Tooth type 1B (CMT1B) disease, one of the most common forms of demyelinating neuropathy. Pathogenesis of some MPZ mutants, such as S63del and R98C, involves the misfolding and retention of MPZ in the endoplasmic reticulum (ER) of myelinating Schwann cells. To cope with proteotoxic ER-stress, Schwann cells mount an unfolded protein response (UPR) characterized by activation of the PERK, ATF6 and IRE1α/XBP1 pathways. Previous results showed that targeting the PERK UPR pathway mitigates neuropathy in mouse models of CMT1B; however, the contributions of other UPR pathways in disease pathogenesis remains poorly understood. Here, we probe the importance of the IRE1α/XBP1 signalling during normal myelination and in CMT1B. In response to ER stress, IRE1α is activated to stimulate the non-canonical splicing of Xbp1 mRNA to generate spliced Xbp1 (Xbp1s). This results in the increased expression of the adaptive transcription factor XBP1s, which regulates the expression of genes involved in diverse pathways including ER proteostasis. We generated mouse models where Xbp1 is deleted specifically in Schwann cells, preventing XBP1s activation in these cells. We observed that Xbp1 is dispensable for normal developmental myelination, myelin maintenance and remyelination after injury. However, Xbp1 deletion dramatically worsens the hypomyelination and the electrophysiological and locomotor parameters observed in young and adult CMT1B neuropathic animals. RNAseq analysis suggested that XBP1s exerts its adaptive function in CMT1B mouse models in large part via the induction of ER proteostasis genes. Accordingly, the exacerbation of the neuropathy in Xbp1 deficient mice was accompanied by upregulation of ER-stress pathways and of IRE1-mediated RIDD signaling in Schwann cells, suggesting that the activation of XBP1s via IRE1 plays a critical role in limiting mutant protein toxicity and that this toxicity cannot be compensated by other stress responses. Schwann cell specific overexpression of XBP1s partially re-established Schwann cell proteostasis and attenuated CMT1B severity in both the S63del and R98C mouse models. In addition, the selective, pharmacologic activation of IRE1α/XBP1 signaling ameliorated myelination in S63del dorsal root ganglia explants. Collectively, these data show that XBP1 has an essential adaptive role in different models of proteotoxic CMT1B neuropathy and suggest that activation of the IRE1α/XBP1 pathway may represent a therapeutic avenue in CMT1B and possibly for other neuropathies characterized by UPR activation.
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Affiliation(s)
- Thierry Touvier
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Francesca A Veneri
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Anke Claessens
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Cinzia Ferri
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Rosa Mastrangelo
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Noémie Sorgiati
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Francesca Bianchi
- Institute of Experimental Neurology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Serena Valenzano
- Institute of Experimental Neurology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, 20157 Milan, Italy
- University of Camerino, Center for Neuroscience, 62032 Camerino, Italy
| | - Ubaldo Del Carro
- Institute of Experimental Neurology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Cristina Rivellini
- Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Phu Duong
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242 USA
| | - Jeffery W Kelly
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - John Svaren
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - R Luke Wiseman
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Maurizio D'Antonio
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
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VerPlank JJS, Gawron J, Silvestri NJ, Feltri ML, Wrabetz L, Goldberg AL. Raising cGMP restores proteasome function and myelination in mice with a proteotoxic neuropathy. Brain 2022; 145:168-178. [PMID: 34382059 PMCID: PMC9126006 DOI: 10.1093/brain/awab249] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/12/2021] [Accepted: 06/16/2021] [Indexed: 11/14/2022] Open
Abstract
Agents that raise cyclic guanosine monophosphate (cGMP) by activating protein kinase G increase 26S proteasome activities, protein ubiquitination and degradation of misfolded proteins. Therefore, they may be useful in treating neurodegenerative and other diseases caused by an accumulation of misfolded proteins. Mutations in myelin protein zero (MPZ) cause the peripheral neuropathy Charcot-Marie-Tooth type 1B (CMT1B). In peripheral nerves of a mouse model of CMT1B, where the mutant MPZS63del is expressed, proteasome activities are reduced, mutant MPZS63del and polyubiquitinated proteins accumulate and the unfolded protein response (p-eif2α) is induced. In HEK293 cells, raising cGMP stimulated ubiquitination and degradation of MPZS63del, but not of wild-type MPZ. Treating S63del mice with the phosphodiesterase 5 inhibitor, sildenafil-to raise cGMP-increased proteasome activity in sciatic nerves and reduced the levels of polyubiquitinated proteins, the proteasome reporter ubG76V-GFP and p-elF2α. Furthermore, sildenafil treatment reduced the number of amyelinated axons, and increased myelin thickness and nerve conduction velocity in sciatic nerves. Thus, agents that raise cGMP, including those widely used in medicine, may be useful therapies for CMT1B and other proteotoxic diseases.
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Affiliation(s)
- Jordan J S VerPlank
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
- Department of Biochemistry, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Department of Neurology, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Joseph Gawron
- Department of Biochemistry, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Department of Neurology, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Nicholas J Silvestri
- Department of Biochemistry, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Department of Neurology, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - M Laura Feltri
- Department of Biochemistry, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Department of Neurology, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Lawrence Wrabetz
- Department of Biochemistry, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Department of Neurology, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Alfred L Goldberg
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
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Abstract
Demyelinating forms of Charcot-Marie-Tooth disease (CMT) are genetically and phenotypically heterogeneous and result from highly diverse biological mechanisms including gain of function (including dominant negative effects) and loss of function. While no definitive treatment is currently available, rapid advances in defining the pathomechanisms of demyelinating CMT have led to promising pre-clinical studies, as well as emerging clinical trials. Especially promising are the recently completed pre-clinical genetic therapy studies in PMP-22, GJB1, and SH3TC2-associated neuropathies, particularly given the success of similar approaches in humans with spinal muscular atrophy and transthyretin familial polyneuropathy. This article focuses on neuropathies related to mutations in PMP-22, MPZ, and GJB1, which together comprise the most common forms of demyelinating CMT, as well as on select rarer forms for which promising treatment targets have been identified. Clinical characteristics and pathomechanisms are reviewed in detail, with emphasis on therapeutically targetable biological pathways. Also discussed are the challenges facing the CMT research community in its efforts to advance the rapidly evolving biological insights to effective clinical trials. These considerations include the limitations of currently available animal models, the need for personalized medicine approaches/allele-specific interventions for select forms of demyelinating CMT, and the increasing demand for optimal clinical outcome assessments and objective biomarkers.
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Affiliation(s)
- Vera Fridman
- Department of Neurology, University of Colorado Anschutz Medical Campus, 12631 E 17th Avenue, Mailstop B185, Room 5113C, Aurora, CO, 80045, USA.
| | - Mario A Saporta
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
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Wrestling and Wrapping: A Perspective on SUMO Proteins in Schwann Cells. Biomolecules 2021; 11:biom11071055. [PMID: 34356679 PMCID: PMC8301837 DOI: 10.3390/biom11071055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 11/20/2022] Open
Abstract
Schwann cell development and peripheral nerve myelination are finely orchestrated multistep processes; some of the underlying mechanisms are well described and others remain unknown. Many posttranslational modifications (PTMs) like phosphorylation and ubiquitination have been reported to play a role during the normal development of the peripheral nervous system (PNS) and in demyelinating neuropathies. However, a relatively novel PTM, SUMOylation, has not been studied in these contexts. SUMOylation involves the covalent attachment of one or more small ubiquitin-like modifier (SUMO) proteins to a substrate, which affects the function, cellular localization, and further PTMs of the conjugated protein. SUMOylation also regulates other proteins indirectly by facilitating non-covalent protein–protein interaction via SUMO interaction motifs (SIM). This pathway has important consequences on diverse cellular processes, and dysregulation of this pathway has been reported in several diseases including neurological and degenerative conditions. In this article, we revise the scarce literature on SUMOylation in Schwann cells and the PNS, we propose putative substrate proteins, and we speculate on potential mechanisms underlying the possible involvement of this PTM in peripheral myelination and neuropathies.
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Sidoli M, Reed CB, Scapin C, Paez P, Cavener DR, Kaufman RJ, D'Antonio M, Feltri ML, Wrabetz L. Calcineurin Activity Is Increased in Charcot-Marie-Tooth 1B Demyelinating Neuropathy. J Neurosci 2021; 41:4536-4548. [PMID: 33879538 PMCID: PMC8152608 DOI: 10.1523/jneurosci.2384-20.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 03/08/2021] [Accepted: 03/17/2021] [Indexed: 11/21/2022] Open
Abstract
Schwann cells produce a considerable amount of lipids and proteins to form myelin in the PNS. For this reason, the quality control of myelin proteins is crucial to ensure proper myelin synthesis. Deletion of serine 63 from P0 (P0S63del) protein in myelin forming Schwann cells causes Charcot-Marie-Tooth type 1B neuropathy in humans and mice. Misfolded P0S63del accumulates in the ER of Schwann cells where it elicits the unfolded protein response (UPR). PERK is the UPR transducer that attenuates global translation and reduces ER stress by phosphorylating the translation initiation factor eIF2alpha. Paradoxically, Perk ablation in P0S63del Schwann cells (S63del/PerkSCKO ) reduced the level of P-eIF2alpha, leaving UPR markers upregulated, yet unexpectedly improved S63del myelin defects in vivo We therefore investigated the hypothesis that PERK may interfere with signals outside of the UPR and specifically with calcineurin/NFATc4 pro-myelinating pathway. Using mouse genetics including females and males in our experimental setting, we show that PERK and calcineurin interact in P0S63del nerves and that calcineurin activity and NFATc4 nuclear localization are increased in S63del Schwann cells, without altering EGR2/KROX20 expression. Moreover, genetic manipulation of the calcineurin subunits appears to be either protective or toxic in S63del in a context-dependent manner, suggesting that Schwann cells are highly sensitive to alterations of calcineurin activity.SIGNIFICANCE STATEMENT Our work shows a novel activity and function for calcineurin in Schwann cells in the context of ER stress. Schwann cells expressing the S63del mutation in P0 protein induce the unfolded protein response and upregulate calcineurin activity. Calcineurin interacts with the ER stress transducer PERK, but the relationship between the UPR and calcineurin in Schwann cells is unclear. Here we propose a protective role for calcineurin in S63del neuropathy, although Schwann cells appear to be very sensitive to its regulation. The paper uncovers a new important role for calcineurin in a demyelinating diseases.
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Affiliation(s)
- Mariapaola Sidoli
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Developmental Biology, School of Medicine, Stanford University, Stanford, California 94305
| | - Chelsey B Reed
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
| | - Cristina Scapin
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT, Milan 20132, Italy
| | - Pablo Paez
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
| | - Douglas R Cavener
- Department of Biology, Center for Cellular Dynamics, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037
| | - Maurizio D'Antonio
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT, Milan 20132, Italy
| | - M Laura Feltri
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
| | - Lawrence Wrabetz
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
- Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
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Scapin C, Ferri C, Pettinato E, Bianchi F, Del Carro U, Feltri ML, Kaufman RJ, Wrabetz L, D'Antonio M. Phosphorylation of eIF2α Promotes Schwann Cell Differentiation and Myelination in CMT1B Mice with Activated UPR. J Neurosci 2020; 40:8174-8187. [PMID: 32973043 PMCID: PMC7574653 DOI: 10.1523/jneurosci.0957-20.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/09/2020] [Accepted: 07/27/2020] [Indexed: 01/01/2023] Open
Abstract
Myelin Protein Zero (MPZ/P0) is the most abundant glycoprotein of peripheral nerve myelin. P0 is synthesized by myelinating Schwann cells, processed in the endoplasmic reticulum (ER) and delivered to myelin via the secretory pathway. The mutant P0S63del (deletion of serine 63 in the extracellular domain of P0), that causes Charcot-Marie-Tooth type 1B (CMT1B) neuropathy in humans and a similar demyelinating neuropathy in transgenic mice, is instead retained the ER where it activates an unfolded protein response. Under ER-stress conditions, protein kinase R-like endoplasmic reticulum kinase (PERK) phosphorylates eukaryotic initiation factor 2α (eIF2α) to attenuate global translation, thus reducing the misfolded protein overload in the ER. Genetic and pharmacological inactivation of Gadd34 (damage-inducible protein 34), a subunit of the PP1 phosphatase complex that promotes the dephosphorylation of eIF2α, prolonged eIF2α phosphorylation and improved motor, neurophysiological, and morphologic deficits in S63del mice. However, PERK ablation in S63del Schwann cells ameliorated, rather than worsened, S63del neuropathy despite reduced levels of phosphorylated eIF2α. These contradictory findings prompted us to genetically explore the role of eIF2α phosphorylation in P0S63del-CMT1B neuropathy through the generation of mice in which eIF2α cannot be phosphorylated specifically in Schwann cells. Morphologic and electrophysiological analysis of male and female S63del mice showed a worsening of the neuropathy in the absence of eIF2α phosphorylation. However, we did not detect significant changes in ER stress levels, but rather a dramatic increase of the MEK/ERK/c-Jun pathway accompanied by a reduction in expression of myelin genes and a delay in Schwann cell differentiation. Our results support the hypothesis that eIF2α phosphorylation is protective in CMT1B and unveil a possible cross talk between eIF2α and the MEK/ERK pathway in neuropathic nerves.SIGNIFICANCE STATEMENT In the P0S63del (deletion of serine 63 in the extracellular domain of P0) mouse model of Charcot-Marie-Tooth type 1B (CMT1B), the genetic and pharmacological inhibition of Gadd34 (damage-inducible protein 34) prolonged eukaryotic initiation factor 2α (eIF2α) phosphorylation, leading to a proteostatic rebalance that significantly ameliorated the neuropathy. Yet, ablation of protein kinase R-like endoplasmic reticulum kinase (PERK) also ameliorated the S63del neuropathy, despite reduced levels of eIF2α phosphorylation (P-eIF2α). In this study, we provide genetic evidence that eIF2α phosphorylation has a protective role in CMT1B Schwann cells by limiting ERK/c-Jun hyperactivation. Our data support the targeting of the P-eIF2α/Gadd34 complex as a therapeutic avenue in CMT1B and also suggest that PERK may hamper myelination via mechanisms outside its role in the unfolded protein response.
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Affiliation(s)
- Cristina Scapin
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Cinzia Ferri
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Emanuela Pettinato
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Francesca Bianchi
- Institute of Experimental Neurology, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Ubaldo Del Carro
- Institute of Experimental Neurology, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - M Laura Feltri
- Hunter James Kelly Research Institute, State University of New York at Buffalo, Buffalo, New York 14203
- Department of Neurology, State University of New York at Buffalo, Buffalo, New York 14203
- Department of Biochemistry, Jacob School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14203
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, California 92130
| | - Lawrence Wrabetz
- Hunter James Kelly Research Institute, State University of New York at Buffalo, Buffalo, New York 14203
- Department of Neurology, State University of New York at Buffalo, Buffalo, New York 14203
- Department of Biochemistry, Jacob School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14203
| | - Maurizio D'Antonio
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milan, Italy
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Wu S, Stone S, Yue Y, Lin W. Endoplasmic reticulum associated degradation is required for maintaining endoplasmic reticulum homeostasis and viability of mature Schwann cells in adults. Glia 2020; 69:489-506. [PMID: 32935902 DOI: 10.1002/glia.23910] [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: 05/05/2020] [Revised: 08/26/2020] [Accepted: 08/30/2020] [Indexed: 01/11/2023]
Abstract
The integrated unfolded protein response (UPR) and endoplasmic reticulum associated degradation (ERAD) is the principle mechanisms that maintain endoplasmic reticulum (ER) homeostasis. Schwann cells (SCs) must produce an enormous amount of myelin proteins via the ER to assemble and maintain myelin structure; however, it is unclear how SCs maintain ER homeostasis. It is known that Suppressor/Enhancer of Lin-12-like (Sel1L) is necessary for the ERAD activity of the Sel1L- hydroxymethylglutaryl reductase degradation protein 1(Hrd1) complex. Herein, we showed that Sel1L deficiency in SCs impaired the ERAD activity of the Sel1L-Hrd1 complex and led to ER stress and activation of the UPR. Interestingly, Sel1L deficiency had no effect on actively myelinating SCs during development, but led to later-onset mature SC apoptosis and demyelination in the adult PNS. Moreover, inactivation of the pancreatic ER kinase (PERK) branch of the UPR did not influence the viability and function of actively myelinating SCs, but resulted in exacerbation of ER stress and apoptosis of mature SCs in SC-specific Sel1L deficient mice. These findings suggest that the integrated UPR and ERAD is dispensable to actively myelinating SCs during development, but is necessary for maintaining ER homeostasis and the viability and function of mature SCs in adults.
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Affiliation(s)
- Shuangchan Wu
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA.,Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sarrabeth Stone
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA.,Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yuan Yue
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA.,Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Wensheng Lin
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA.,Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
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10
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Costa-Mattioli M, Walter P. The integrated stress response: From mechanism to disease. Science 2020; 368:368/6489/eaat5314. [PMID: 32327570 DOI: 10.1126/science.aat5314] [Citation(s) in RCA: 668] [Impact Index Per Article: 167.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Protein quality control is essential for the proper function of cells and the organisms that they make up. The resulting loss of proteostasis, the processes by which the health of the cell's proteins is monitored and maintained at homeostasis, is associated with a wide range of age-related human diseases. Here, we highlight how the integrated stress response (ISR), a central signaling network that responds to proteostasis defects by tuning protein synthesis rates, impedes the formation of long-term memory. In addition, we address how dysregulated ISR signaling contributes to the pathogenesis of complex diseases, including cognitive disorders, neurodegeneration, cancer, diabetes, and metabolic disorders. The development of tools through which the ISR can be modulated promises to uncover new avenues to diminish pathologies resulting from it for clinical benefit.
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Affiliation(s)
- Mauro Costa-Mattioli
- Department of Neuroscience, Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA.
| | - Peter Walter
- Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, CA, USA.
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11
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Abstract
Activation of the unfolded protein response in response to endoplasmic reticulum stress preserves cell viability and function under stressful conditions. Nevertheless, persistent, unresolvable activation of the unfolded protein response can trigger apoptosis to eliminate stressed cells. Recent studies show that the unfolded protein response plays an important role in the pathogenesis of various disorders of myelin, including multiples sclerosis, Charcot-Marie-Tooth disease, Pelizaeus-Merzbacher disease, vanishing white matter disease, spinal cord injury, tuberous sclerosis complex, and hypoxia-induced perinatal white matter injury. In this review we summarize the current literature on the unfolded protein response and the evidence for its role in the pathogenesis of myelin disorders.
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Affiliation(s)
- Wensheng Lin
- Department of Neuroscience; Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Sarrabeth Stone
- Department of Neuroscience; Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA
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12
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Volpi VG, Ferri C, Fregno I, Del Carro U, Bianchi F, Scapin C, Pettinato E, Solda T, Feltri ML, Molinari M, Wrabetz L, D’Antonio M. Schwann cells ER-associated degradation contributes to myelin maintenance in adult nerves and limits demyelination in CMT1B mice. PLoS Genet 2019; 15:e1008069. [PMID: 30995221 PMCID: PMC6488099 DOI: 10.1371/journal.pgen.1008069] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 04/29/2019] [Accepted: 03/06/2019] [Indexed: 12/19/2022] Open
Abstract
In the peripheral nervous system (PNS) myelinating Schwann cells synthesize large amounts of myelin protein zero (P0) glycoprotein, an abundant component of peripheral nerve myelin. In humans, mutations in P0 cause the demyelinating Charcot-Marie-Tooth 1B (CMT1B) neuropathy, one of the most diffused genetic disorders of the PNS. We previously showed that several mutations, such as the deletion of serine 63 (P0-S63del), result in misfolding and accumulation of P0 in the endoplasmic reticulum (ER), with activation of the unfolded protein response (UPR). In addition, we observed that S63del mouse nerves display the upregulation of many ER-associated degradation (ERAD) genes, suggesting a possible involvement of this pathway in the clearance of the mutant P0. In ERAD in fact, misfolded proteins are dislocated from the ER and targeted for proteasomal degradation. Taking advantage of inducible cells that express the ER retained P0, here we show that the P0-S63del glycoprotein is degraded via ERAD. Moreover, we provide strong evidence that the Schwann cell-specific ablation of the ERAD factor Derlin-2 in S63del nerves exacerbates both the myelin defects and the UPR in vivo, unveiling a protective role for ERAD in CMT1B neuropathy. We also found that lack of Derlin-2 affects adult myelin maintenance in normal nerves, without compromising their development, pinpointing ERAD as a previously unrecognized player in preserving Schwann cells homeostasis in adulthood. Finally, we provide evidence that treatment of S63del peripheral nerve cultures with N-Acetyl-D-Glucosamine (GlcNAc), known to enhance protein quality control pathways in C.elegans, ameliorates S63del nerve myelination ex vivo. Overall, our study suggests that potentiating adaptive ER quality control pathways might represent an appealing strategy to treat both conformational and age-related PNS disorders. Charcot-Marie-Tooth neuropathies are a large family of peripheral nerve disorders, showing extensive clinical and genetic heterogeneity. Although strong advances have been made in the identification of genes and mutations involved, effective therapies are still lacking. Intracellular retention of abnormal proteins has been recently suggested as one of the pathogenetic events that might underlie several conformational neuropathies. To limit the toxic effects of accumulated mutant proteins, cells have developed efficient protein quality control systems aimed at optimizing both protein folding and degradation. Here we show that ER-associated degradation limits Schwann cells stress and myelin defects caused by the accumulation of a mutant myelin protein into the ER. In addition, we also describe for the first time the importance of Schwann cells ERAD in preserving myelin integrity in adult nerves, showing that genetic ERAD impairment leads to a late onset, motor-predominant, peripheral neuropathy in vivo. Effort in the design of strategies that potentiate ERAD and ER quality controls is therefore highly desirable.
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Affiliation(s)
- Vera G. Volpi
- Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Cinzia Ferri
- Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Ilaria Fregno
- Instuitute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
- Department of Biology, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Ubaldo Del Carro
- Institute of Experimental Neurology (INSPE), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Francesca Bianchi
- Institute of Experimental Neurology (INSPE), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Cristina Scapin
- Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Emanuela Pettinato
- Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Tatiana Solda
- Instuitute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
| | - M. Laura Feltri
- Hunter James Kelly Research Institute, University at Buffalo, Buffalo, New York, United States of America
- Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, United States of America
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Maurizio Molinari
- Instuitute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona, Switzerland
- School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Lawrence Wrabetz
- Hunter James Kelly Research Institute, University at Buffalo, Buffalo, New York, United States of America
- Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, United States of America
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Maurizio D’Antonio
- Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- * E-mail:
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13
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Elitt MS, Shick HE, Madhavan M, Allan KC, Clayton BLL, Weng C, Miller TE, Factor DC, Barbar L, Nawash BS, Nevin ZS, Lager AM, Li Y, Jin F, Adams DJ, Tesar PJ. Chemical Screening Identifies Enhancers of Mutant Oligodendrocyte Survival and Unmasks a Distinct Pathological Phase in Pelizaeus-Merzbacher Disease. Stem Cell Reports 2018; 11:711-726. [PMID: 30146490 PMCID: PMC6135742 DOI: 10.1016/j.stemcr.2018.07.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 07/30/2018] [Accepted: 07/30/2018] [Indexed: 01/15/2023] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a fatal X-linked disorder caused by loss of myelinating oligodendrocytes and consequent hypomyelination. The underlying cellular and molecular dysfunctions are not fully defined, but therapeutic enhancement of oligodendrocyte survival could restore functional myelination in patients. Here we generated pure, scalable quantities of induced pluripotent stem cell-derived oligodendrocyte progenitor cells (OPCs) from a severe mouse model of PMD, Plp1jimpy. Temporal phenotypic and transcriptomic studies defined an early pathological window characterized by endoplasmic reticulum (ER) stress and cell death as OPCs exit their progenitor state. High-throughput phenotypic screening identified a compound, Ro 25-6981, which modulates the ER stress response and rescues mutant oligodendrocyte survival in jimpy, in vitro and in vivo, and in human PMD oligocortical spheroids. Surprisingly, increasing oligodendrocyte survival did not restore subsequent myelination, revealing a second pathological phase. Collectively, our work shows that PMD oligodendrocyte loss can be rescued pharmacologically and defines a need for multifactorial intervention to restore myelination.
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Affiliation(s)
- Matthew S Elitt
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - H Elizabeth Shick
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Mayur Madhavan
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Kevin C Allan
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Benjamin L L Clayton
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Chen Weng
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Tyler E Miller
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Daniel C Factor
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Lilianne Barbar
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Baraa S Nawash
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Zachary S Nevin
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Angela M Lager
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Yan Li
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Fulai Jin
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Engineering and Computer Science, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Drew J Adams
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Paul J Tesar
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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14
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Phan V, Schmidt J, Matyash V, Malchow S, Thanisch M, Lorenz C, Diepolder I, Schulz JB, Stenzel W, Roos A, Gess B. Characterization of Naïve and Vitamin C-Treated Mouse Schwann Cell Line MSC80: Induction of the Antioxidative Thioredoxin Related Transmembrane Protein 1. J Proteome Res 2018; 17:2925-2936. [PMID: 30044099 DOI: 10.1021/acs.jproteome.8b00022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Schwann cells (SCs) are essential in the production of the axon-wrapping myelin sheath and provide trophic function and repair mechanisms in the peripheral nerves. Consequently, well-characterized SC in vitro models are needed to perform preclinical studies including the investigation of the complex biochemical adaptations occurring in the peripheral nervous system (PNS) under different (patho)physiological conditions. MSC80 cells represent a murine SC line used as an in vitro system for neuropathological studies. Here, we introduce the most abundant 9532 proteins identified via mass spectrometry-based protein analytics, and thus provide the most comprehensive SC protein catalogue published thus far. We cover proteins causative for inherited neuropathies and demonstrate that in addition to cytoplasmic, nuclear and mitochondrial proteins and others belonging to the protein processing machinery are very well covered. Moreover, we address the suitability of MSC80 to examine the molecular effect of a drug-treatment by analyzing the proteomic signature of Vitamin C-treated cells. Proteomic findings, immunocytochemistry, immunoblotting and functional experiments support the concept of a beneficial role of Vitamin C on oxidative stress and identified TMX1 as an oxidative stress protective factor, which might represent a promising avenue for therapeutic intervention of PNS-disorders with oxidative stress burden such as diabetic neuropathy.
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Affiliation(s)
- Vietxuan Phan
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V. , 44227 Dortmund , Germany
| | - Jens Schmidt
- Department of Neurology , University Hospital RWTH Aachen , Aachen , Germany
| | - Vitali Matyash
- Department of Neuropathology , Charité - Universitätsmedizin , Berlin , Germany
| | - Sebastian Malchow
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V. , 44227 Dortmund , Germany
| | - Michaela Thanisch
- Department of Neurology , University Hospital RWTH Aachen , Aachen , Germany
| | - Christin Lorenz
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V. , 44227 Dortmund , Germany
| | - Irmgard Diepolder
- Department of Neurology , University Hospital RWTH Aachen , Aachen , Germany
| | - Jörg Bernhard Schulz
- Department of Neurology , University Hospital RWTH Aachen , Aachen , Germany.,JARA-BRAIN Institute Molecular Neuroscience and Neuroimaging , Forschungszentrum Jülich GmbH and RWTH Aachen University , Aachen , Germany
| | - Werner Stenzel
- Department of Neuropathology , Charité - Universitätsmedizin , Berlin , Germany
| | - Andreas Roos
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V. , 44227 Dortmund , Germany
| | - Burkhard Gess
- Department of Neurology , University Hospital RWTH Aachen , Aachen , Germany
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15
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Ablation of Perk in Schwann Cells Improves Myelination in the S63del Charcot-Marie-Tooth 1B Mouse. J Neurosci 2017; 36:11350-11361. [PMID: 27807175 DOI: 10.1523/jneurosci.1637-16.2016] [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: 05/21/2016] [Accepted: 08/09/2016] [Indexed: 12/12/2022] Open
Abstract
In factory cells, the accumulation of misfolded protein provokes the unfolded protein response (UPR). For example, deletion of serine 63 (S63del) in myelin protein zero (P0) induces P0 accumulation in the endoplasmic reticulum (ER) of Schwann cells and a persistent UPR associated with Charcot-Marie-Tooth 1B (CMT1B) demyelinating peripheral neuropathy in human and mouse. PERK (protein kinase RNA-like ER kinase) is the ER stress sensor that attenuates global translation by phosphorylating eIF2α. Inhibition of the eIF2α holophosphatase GADD34:PP1, increases the phosphorylation of eIF2α in Schwann cells and largely rescues S63del neuropathy. Nonetheless, reducing phosphorylation of eIF2α, by Perk haploinsufficiency, also ameliorates the myelin defects of S63del nerves. This contradictory finding prompted us to investigate whether the beneficial effect of Perk deficiency on myelination could derive from neurons. To test this hypothesis, we generated and compared Schwann cell- and neuron-specific ablation of Perk in S63del nerves. Our data suggest that the detrimental effect of Perk in CMT1B derives primarily from Schwann cells. Furthermore, we show that Perk loss of function in Schwann cells restores myelination without diminishing accumulation of P0 or markers of ER stress, suggesting that Perk may modulate myelination through a pathway independent of the UPR. SIGNIFICANCE STATEMENT In many endoplasmic reticulum (ER) stress-related disorders, activation of the unfolded protein sensor protein kinase RNA-like ER kinase (PERK) kinase is beneficial. Nonetheless, in Charcot-Marie-Tooth 1B neuropathy mice, we show that activation of PERK in Schwann cells, but not in neurons, is detrimental for myelination. PERK may interfere with myelination, independent of its role in ER stress.
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16
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Volpi VG, Touvier T, D'Antonio M. Endoplasmic Reticulum Protein Quality Control Failure in Myelin Disorders. Front Mol Neurosci 2017; 9:162. [PMID: 28101003 PMCID: PMC5209374 DOI: 10.3389/fnmol.2016.00162] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 12/16/2016] [Indexed: 12/24/2022] Open
Abstract
Reaching the correct three-dimensional structure is crucial for the proper function of a protein. The endoplasmic reticulum (ER) is the organelle where secreted and transmembrane proteins are synthesized and folded. To guarantee high fidelity of protein synthesis and maturation in the ER, cells have evolved ER-protein quality control (ERQC) systems, which assist protein folding and promptly degrade aberrant gene products. Only correctly folded proteins that pass ERQC checkpoints are allowed to exit the ER and reach their final destination. Misfolded glycoproteins are detected and targeted for degradation by the proteasome in a process known as endoplasmic reticulum-associated degradation (ERAD). The excess of unstructured proteins in the ER triggers an adaptive signal transduction pathway, called unfolded protein response (UPR), which in turn potentiates ERQC activities in order to reduce the levels of aberrant molecules. When the situation cannot be restored, the UPR drives cells to apoptosis. Myelin-forming cells of the central and peripheral nervous system (oligodendrocytes and Schwann cells) synthesize a large amount of myelin proteins and lipids and therefore are particularly susceptible to ERQC failure. Indeed, deficits in ERQC and activation of ER stress/UPR have been implicated in several myelin disorders, such as Pelizaeus-Merzbacher and Krabbe leucodystrophies, vanishing white matter disease and Charcot-Marie-Tooth neuropathies. Here we discuss recent evidence underlying the importance of proper ERQC functions in genetic disorders of myelinating glia.
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Affiliation(s)
- Vera G Volpi
- Biology of Myelin Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT Milan, Italy
| | - Thierry Touvier
- Biology of Myelin Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT Milan, Italy
| | - Maurizio D'Antonio
- Biology of Myelin Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, DIBIT Milan, Italy
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