1
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VerPlank JJ, Gawron JM, Silvestri NJ, Wrabetz L, Feltri ML. Knockout of PA200 improves proteasomal degradation and myelination in a proteotoxic neuropathy. Life Sci Alliance 2024; 7:e202302349. [PMID: 38320810 PMCID: PMC10847332 DOI: 10.26508/lsa.202302349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/12/2024] Open
Abstract
The cellular response to a decrease in protein degradation by 26S proteasomes in chronic diseases is poorly understood. Pharmacological inhibition of proteasomes increases the expression of proteasome subunits and Proteasome Activator 200 (PA200), an alternative proteasome activator. In the S63del mouse model of the peripheral neuropathy Charcot Marie Tooth 1B (CMT1B), proteasomal protein degradation is decreased and proteasome gene expression is increased. Here, we show an increase in PA200 and PA200-bound proteasomes in the peripheral nerves of S63del mice. To test genetically whether the upregulation of PA200 was compensatory, we generated S63del//PA200-/- mice. Unexpectedly, in the sciatic nerves of these mice, there was greater proteasomal protein degradation than in S63del, less polyubiquitinated proteins and markers of the unfolded protein response, and a greater amount of assembled, active 26S proteasomes. These changes were not seen in PA200-/- controls and were therefore specific to the neuropathy. Furthermore, in S63del//PA200-/- mice, myelin thickness and nerve conduction were restored to WT levels. Thus, the upregulation of PA200 is maladaptive in S63del mice and its genetic ablation prevented neuropathy.
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Affiliation(s)
- Jordan Js VerPlank
- https://ror.org/01y64my43 Department of Biochemistry, Institute for Myelin and Glia Exploration, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Joseph M Gawron
- https://ror.org/01y64my43 Department of Biochemistry, Institute for Myelin and Glia Exploration, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Nicholas J Silvestri
- Department of Neurology, Institute for Myelin and Glia Exploration, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Lawrence Wrabetz
- https://ror.org/01y64my43 Department of Biochemistry, Institute for Myelin and Glia Exploration, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
- Department of Neurology, Institute for Myelin and Glia Exploration, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Maria Laura Feltri
- https://ror.org/01y64my43 Department of Biochemistry, Institute for Myelin and Glia Exploration, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
- Department of Neurology, Institute for Myelin and Glia Exploration, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
- IRCCS Neurological Institute "Carlo Besta," Milano, Italy
- Department of Medical Biotechnology and Translational Medicine, Universita' degli Studi di Milano, Milano, Italy
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2
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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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3
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Na Y, Hall A, Yu Y, Hu L, Choi K, Burgard JA, Szabo S, Huang G, Ratner N, Wu J. Runx1/3-driven adaptive endoplasmic reticulum stress pathways contribute to neurofibromagenesis. Oncogene 2023; 42:1038-1047. [PMID: 36759572 PMCID: PMC10194627 DOI: 10.1038/s41388-023-02620-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 01/28/2023] [Accepted: 01/31/2023] [Indexed: 02/11/2023]
Abstract
Neurofibromatosis type 1 (NF1) patients are predisposed to develop plexiform neurofibromas (PNFs). Three endoplasmic reticulum (ER) stress response pathways restore cellular homeostasis. The unfolded protein response (UPR) sensors contribute to tumor initiation in many cancers. We found that all three UPR pathways were activated in mouse and human PNFs, with protein kinase RNA [PKR]-like ER kinase (PERK) the most highly expressed. We tested if neurofibroma cells adapt to ER stress, leading to their growth. Pharmacological or genetic inhibition of PERK reduced mouse neurofibroma-sphere number, and genetic inhibition in PERK in Schwann cell precursors (SCPs) decreased tumor-like lesion numbers in a cell transplantation model. Further, in a PNF mouse model, deletion of PERK in Schwann cells (SCs) and SCPs reduced tumor size, number, and increased survival. Mechanistically, loss of Nf1 activated PERK-eIF2α-ATF4 signaling and increased ATF4 downstream target gene p21 translocation from nucleus to cytoplasm. This nucleus-cytoplasm translocation was mediated by exportin-1. Runx transcriptionally activated ribosome gene expression and increased protein synthesis to allow SCs to adapt to ER stress and tumor formation. We propose that targeting proteostasis might provide cytotoxic and/or potentially durable novel therapy for PNFs.
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Affiliation(s)
- Youjin Na
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
| | - Ashley Hall
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
| | - Yanan Yu
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
- College of Life Science, Xuzhou Medical University, 221004, Jiangsu, P. R. China
| | - Liang Hu
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
| | - Kwangmin Choi
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
| | - Jake A Burgard
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
| | - Sara Szabo
- Department of Pediatrics and Department of Pediatric Pathology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Gang Huang
- Department of Cell Systems & Anatomy and Department of Pathology & Laboratory Medicine, UT Health San Antonio, Joe R. and Teresa Lozano Long School of Medicine, Mays Cancer Center at UT Health San Antonio, San Antonio, TX, USA
- Department of Pathology & Laboratory Medicine, UT Health San Antonio, Joe R. and Teresa Lozano Long School of Medicine, Mays Cancer Center at UT Health San Antonio, San Antonio, TX, 78229, USA
| | - Nancy Ratner
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA
| | - Jianqiang Wu
- Division of Experimental Hematology and Cancer Biology, Cancer & Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA.
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA.
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4
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Kaur S, Zhang X, Patel S, Rodriguez YA, Luther KJ, Alghafli G, Lang RM, Abrams CK, Dobrowsky RT. Pharmacologic Targeting of the C-Terminus of Heat Shock Protein 90 Improves Neuromuscular Function in Animal Models of Charcot Marie Tooth X1 Disease. ACS Pharmacol Transl Sci 2023; 6:306-319. [PMID: 36798471 PMCID: PMC9926526 DOI: 10.1021/acsptsci.2c00223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Indexed: 01/22/2023]
Abstract
Charcot-Marie-Tooth X1 (CMTX1) disease is an inherited peripheral neuropathy that arises from loss-of-function mutations in the protein connexin 32 (Cx32). CMTX1 currently lacks a pharmacologic approach toward disease management, and we have previously shown that modulating the expression of molecular chaperones using novologue therapy may provide a viable disease-modifying approach to treat metabolic and demyelinating neuropathies. Cemdomespib is an orally bioavailable novologue that manifests neuroprotective activity by modulating the expression of heat shock protein 70 (Hsp70). We examined if 1 to 5 months of daily cemdomespib therapy may improve neuropathic symptoms in three mouse models of CMTX1 (Cx32 deficient (Cx32def), T55I-Cx32def, and R75W-Cx32 mice). Daily drug therapy significantly improved motor nerve conduction velocity (MNCV) and grip strength in all three models, but the compound muscle action potential was only improved in Cx32def mice. Drug efficacy required Hsp70 as improvements in MNCV, and the grip strength was abrogated in Cx32def × Hsp70 knockout mice. Five months of novologue therapy was associated with improved neuromuscular junction morphology, femoral motor nerve myelination, reduction in foamy macrophages, and a decrease in Schwann cell c-jun levels. To determine if c-jun may be downstream of Hsp70 and necessary for drug efficacy, c-jun expression was specifically deleted in Schwann cells of Cx32def mice. While the deletion of c-jun worsened the neuropathy, cemdomespib therapy remained effective in improving MNCV and grip strength. Our data show that cemdomespib therapy improves CMTX1-linked neuropathy in an Hsp70-dependent but a c-jun-independent manner and without regard to the nature of the underlying Cx32 mutation.
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Affiliation(s)
- Sukhmanjit Kaur
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
| | - Xinyue Zhang
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
| | - Sugandha Patel
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
| | - Yssa A. Rodriguez
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
| | - Kylie J. Luther
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
| | - Ghufran Alghafli
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan M. Lang
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
| | - Charles K. Abrams
- Department
of Neurology and Rehabilitation and Biomedical Engineering, College
of Medicine, University of Illinois Chicago, Chicago, Illinois 60612, United States
| | - Rick T. Dobrowsky
- Department
of Pharmacology and Toxicology, University
of Kansas, Lawrence, Kansas 66045, United States
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5
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Veneri FA, Prada V, Mastrangelo R, Ferri C, Nobbio L, Passalacqua M, Milanesi M, Bianchi F, Del Carro U, Vallat JM, Duong P, Svaren J, Schenone A, Grandis M, D’Antonio M. A novel mouse model of CMT1B identifies hyperglycosylation as a new pathogenetic mechanism. Hum Mol Genet 2022; 31:4255-4274. [PMID: 35908287 PMCID: PMC9759335 DOI: 10.1093/hmg/ddac170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 01/21/2023] Open
Abstract
Mutations in the Myelin Protein Zero gene (MPZ), encoding P0, the major structural glycoprotein of peripheral nerve myelin, are the cause of Charcot-Marie-Tooth (CMT) type 1B neuropathy, and most P0 mutations appear to act through gain-of-function mechanisms. Here, we investigated how misglycosylation, a pathomechanism encompassing several genetic disorders, may affect P0 function. Using in vitro assays, we showed that gain of glycosylation is more damaging for P0 trafficking and functionality as compared with a loss of glycosylation. Hence, we generated, via CRISPR/Cas9, a mouse model carrying the MPZD61N mutation, predicted to generate a new N-glycosylation site in P0. In humans, MPZD61N causes a severe early-onset form of CMT1B, suggesting that hyperglycosylation may interfere with myelin formation, leading to pathology. We show here that MPZD61N/+ mice develop a tremor as early as P15 which worsens with age and correlates with a significant motor impairment, reduced muscular strength and substantial alterations in neurophysiology. The pathological analysis confirmed a dysmyelinating phenotype characterized by diffuse hypomyelination and focal hypermyelination. We find that the mutant P0D61N does not cause significant endoplasmic reticulum stress, a common pathomechanism in CMT1B, but is properly trafficked to myelin where it causes myelin uncompaction. Finally, we show that myelinating dorsal root ganglia cultures from MPZD61N mice replicate some of the abnormalities seen in vivo, suggesting that they may represent a valuable tool to investigate therapeutic approaches. Collectively, our data indicate that the MPZD61N/+ mouse represents an authentic model of severe CMT1B affirming gain-of-glycosylation in P0 as a novel pathomechanism of disease.
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Affiliation(s)
- Francesca A Veneri
- Biology of Myelin Unit, Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy,Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genova, IRCCS AOU San Martino-IST, 16132 Genova, Italy
| | - Valeria Prada
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genova, IRCCS AOU San Martino-IST, 16132 Genova, Italy
| | - Rosa Mastrangelo
- Biology of Myelin Unit, Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Cinzia Ferri
- Biology of Myelin Unit, Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Lucilla Nobbio
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genova, IRCCS AOU San Martino-IST, 16132 Genova, Italy
| | - Mario Passalacqua
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | - Maria Milanesi
- Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia, 25123 Brescia, Italy
| | - Francesca Bianchi
- Movement Disorders Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Ubaldo Del Carro
- Movement Disorders Unit, Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Jean-Michel Vallat
- Department and Laboratory of Neurology, National Reference Center for ‘Rare Peripheral Neuropathies’, University Hospital of Limoges (CHU Limoges), Dupuytren Hospital, 87000 Limoges, France
| | - Phu Duong
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - John Svaren
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Angelo Schenone
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genova, IRCCS AOU San Martino-IST, 16132 Genova, Italy,Department of Neurology, IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy
| | - Marina Grandis
- To whom correspondence should be addressed at: Department of Neurology, IRCCS Ospedale Policlinico San Martino, Largo Daneo 3, 16132 Genova, Italy. Tel: +39 010 3537562; (M.G.); San Raffaele Scientific Institute, DIBIT, via Olgettina 58, 20132 Milan, Italy. Tel: +39 02 26435307; (M.D.)
| | - Maurizio D’Antonio
- To whom correspondence should be addressed at: Department of Neurology, IRCCS Ospedale Policlinico San Martino, Largo Daneo 3, 16132 Genova, Italy. Tel: +39 010 3537562; (M.G.); San Raffaele Scientific Institute, DIBIT, via Olgettina 58, 20132 Milan, Italy. Tel: +39 02 26435307; (M.D.)
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6
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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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7
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Hines TJ, Lutz C, Murray SA, Burgess RW. An Integrated Approach to Studying Rare Neuromuscular Diseases Using Animal and Human Cell-Based Models. Front Cell Dev Biol 2022; 9:801819. [PMID: 35047510 PMCID: PMC8762301 DOI: 10.3389/fcell.2021.801819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
As sequencing technology improves, the identification of new disease-associated genes and new alleles of known genes is rapidly increasing our understanding of the genetic underpinnings of rare diseases, including neuromuscular diseases. However, precisely because these disorders are rare and often heterogeneous, they are difficult to study in patient populations. In parallel, our ability to engineer the genomes of model organisms, such as mice or rats, has gotten increasingly efficient through techniques such as CRISPR/Cas9 genome editing, allowing the creation of precision human disease models. Such in vivo model systems provide an efficient means for exploring disease mechanisms and identifying therapeutic strategies. Furthermore, animal models provide a platform for preclinical studies to test the efficacy of those strategies. Determining whether the same mechanisms are involved in the human disease and confirming relevant parameters for treatment ideally involves a human experimental system. One system currently being used is induced pluripotent stem cells (iPSCs), which can then be differentiated into the relevant cell type(s) for in vitro confirmation of disease mechanisms and variables such as target engagement. Here we provide a demonstration of these approaches using the example of tRNA-synthetase-associated inherited peripheral neuropathies, rare forms of Charcot-Marie-Tooth disease (CMT). Mouse models have led to a better understanding of both the genetic and cellular mechanisms underlying the disease. To determine if the mechanisms are similar in human cells, we will use genetically engineered iPSC-based models. This will allow comparisons of different CMT-associated GARS alleles in the same genetic background, reducing the variability found between patient samples and simplifying the availability of cell-based models for a rare disease. The necessity of integrating mouse and human models, strategies for accomplishing this integration, and the challenges of doing it at scale are discussed using recently published work detailing the cellular mechanisms underlying GARS-associated CMT as a framework.
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8
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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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9
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Animal Models as a Tool to Design Therapeutical Strategies for CMT-like Hereditary Neuropathies. Brain Sci 2021; 11:brainsci11091237. [PMID: 34573256 PMCID: PMC8465478 DOI: 10.3390/brainsci11091237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 09/05/2021] [Accepted: 09/07/2021] [Indexed: 02/07/2023] Open
Abstract
Since ancient times, animal models have provided fundamental information in medical knowledge. This also applies for discoveries in the field of inherited peripheral neuropathies (IPNs), where they have been instrumental for our understanding of nerve development, pathogenesis of neuropathy, molecules and pathways involved and to design potential therapies. In this review, we briefly describe how animal models have been used in ancient medicine until the use of rodents as the prevalent model in present times. We then travel along different examples of how rodents have been used to improve our understanding of IPNs. We do not intend to describe all discoveries and animal models developed for IPNs, but just to touch on a few arbitrary and paradigmatic examples, taken from our direct experience or from literature. The idea is to show how strategies have been developed to finally arrive to possible treatments for IPNs.
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10
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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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11
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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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12
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Shacham T, Patel C, Lederkremer GZ. PERK Pathway and Neurodegenerative Disease: To Inhibit or to Activate? Biomolecules 2021; 11:biom11030354. [PMID: 33652720 PMCID: PMC7996871 DOI: 10.3390/biom11030354] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/18/2021] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
With the extension of life span in recent decades, there is an increasing burden of late-onset neurodegenerative diseases, for which effective treatments are lacking. Neurodegenerative diseases include the widespread Alzheimer’s disease (AD) and Parkinson’s disease (PD), the less frequent Huntington’s disease (HD) and Amyotrophic Lateral Sclerosis (ALS) and also rare early-onset diseases linked to mutations that cause protein aggregation or loss of function in genes that maintain protein homeostasis. The difficulties in applying gene therapy approaches to tackle these diseases is drawing increasing attention to strategies that aim to inhibit cellular toxicity and restore homeostasis by intervening in cellular pathways. These include the unfolded protein response (UPR), activated in response to endoplasmic reticulum (ER) stress, a cellular affliction that is shared by these diseases. Special focus is turned to the PKR-like ER kinase (PERK) pathway of the UPR as a target for intervention. However, the complexity of the pathway and its ability to promote cell survival or death, depending on ER stress resolution, has led to some confusion in conflicting studies. Both inhibition and activation of the PERK pathway have been reported to be beneficial in disease models, although there are also some reports where they are counterproductive. Although with the current knowledge a definitive answer cannot be given on whether it is better to activate or to inhibit the pathway, the most encouraging strategies appear to rely on boosting some steps without compromising downstream recovery.
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Affiliation(s)
- Talya Shacham
- Cell Biology Division, George Wise Faculty of Life Sciences, The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv 69978, Israel; (T.S.); (C.P.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Chaitanya Patel
- Cell Biology Division, George Wise Faculty of Life Sciences, The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv 69978, Israel; (T.S.); (C.P.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gerardo Z. Lederkremer
- Cell Biology Division, George Wise Faculty of Life Sciences, The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv 69978, Israel; (T.S.); (C.P.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
- Correspondence: ; Tel.: +972-3-640-9239
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13
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Phosphorylation of eIF2α Promotes Schwann Cell Differentiation and Myelination in CMT1B Mice with Activated UPR. J Neurosci 2020; 40:8174-8187. [PMID: 32973043 DOI: 10.1523/jneurosci.0957-20.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [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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14
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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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15
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Deletion of Calcineurin in Schwann Cells Does Not Affect Developmental Myelination, But Reduces Autophagy and Delays Myelin Clearance after Peripheral Nerve Injury. J Neurosci 2020; 40:6165-6176. [PMID: 32641402 DOI: 10.1523/jneurosci.0951-20.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/09/2020] [Accepted: 06/20/2020] [Indexed: 11/21/2022] Open
Abstract
In the PNS, myelination occurs postnatally when Schwann cells (SCs) contact axons. Axonal factors, such as Neuregulin-1 Type III, trigger promyelinating signals that upregulate myelin genes. Neuregulin-1 Type III has been proposed to activate calcineurin signaling in immature SCs to initiate differentiation and myelination. However, little is known about the role of calcineurin in promyelinating SCs after birth. By creating a SC conditional KO of calcineurin B (CnBscko), we assessed the effects of CnB ablation on peripheral myelination after birth in both male and female mice. Surprisingly, CnBscko mice have minimal myelination defects, no alteration of myelin thickness, and normal KROX20 expression. In contrast, we did find a unique role for calcineurin in SCs after nerve injury. Following nerve crush, CnBscko mice have slower degeneration of myelin compared with WT mice. Furthermore, absence of CnB in primary SCs delays clearance of myelin debris. SCs clear myelin via autophagy and recent literature has demonstrated that calcineurin can regulate autophagy via dephosphorylation of transcription factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy. We demonstrate that loss of CnB reduces autophagic flux in primary SCs, indicating a possible mechanism for impaired myelin clearance. In addition, ablation of CnB impairs TFEB translocation to the nucleus 3 d after crush, suggesting that calcineurin may regulate autophagy in SCs via TFEB activation. Together, our data indicate that calcineurin is not essential for myelination but has a novel role in myelin clearance after injury.SIGNIFICANCE STATEMENT Our data offer a novel mechanism for activation of autophagy after peripheral nerve injury. Efficient clearance of myelin after injury by Schwann cells is important for axonal regrowth and remyelination, which is one reason why the PNS is significantly better at recovery compared with the CNS. Improved understanding of myelin clearance allows for the identification of pathways that are potentially accessible to increase myelin clearance and improve remyelination and recovery. Finally, this paper clarifies the role of calcineurin in Schwann cells and myelination.
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16
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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: 643] [Impact Index Per Article: 160.8] [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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17
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Gorbatyuk MS, Starr CR, Gorbatyuk OS. Endoplasmic reticulum stress: New insights into the pathogenesis and treatment of retinal degenerative diseases. Prog Retin Eye Res 2020; 79:100860. [PMID: 32272207 DOI: 10.1016/j.preteyeres.2020.100860] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 03/08/2020] [Accepted: 03/17/2020] [Indexed: 12/13/2022]
Abstract
Physiological equilibrium in the retina depends on coordinated work between rod and cone photoreceptors and can be compromised by the expression of mutant proteins leading to inherited retinal degeneration (IRD). IRD is a diverse group of retinal dystrophies with multifaceted molecular mechanisms that are not fully understood. In this review, we focus on the contribution of chronically activated unfolded protein response (UPR) to inherited retinal pathogenesis, placing special emphasis on studies employing genetically modified animal models. As constitutively active UPR in degenerating retinas may activate pro-apoptotic programs associated with oxidative stress, pro-inflammatory signaling, dysfunctional autophagy, free cytosolic Ca2+ overload, and altered protein synthesis rate in the retina, we focus on the regulatory mechanisms of translational attenuation and approaches to overcoming translational attenuation in degenerating retinas. We also discuss current research on the role of the UPR mediator PERK and its downstream targets in degenerating retinas and highlight the therapeutic benefits of reprogramming PERK signaling in preclinical animal models of IRD. Finally, we describe pharmacological approaches targeting UPR in ocular diseases and consider their potential applications to IRD.
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Affiliation(s)
- Marina S Gorbatyuk
- The University of Alabama at Birmingham, Department of Optometry and Vision Science, School of Optometry, USA.
| | - Christopher R Starr
- The University of Alabama at Birmingham, Department of Optometry and Vision Science, School of Optometry, USA
| | - Oleg S Gorbatyuk
- The University of Alabama at Birmingham, Department of Optometry and Vision Science, School of Optometry, USA
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18
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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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19
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Mercado G, Castillo V, Soto P, López N, Axten JM, Sardi SP, Hoozemans JJ, Hetz C. Targeting PERK signaling with the small molecule GSK2606414 prevents neurodegeneration in a model of Parkinson's disease. Neurobiol Dis 2018; 112:136-148. [DOI: 10.1016/j.nbd.2018.01.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/21/2017] [Accepted: 01/08/2018] [Indexed: 12/14/2022] Open
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20
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Axonal Activation of the Unfolded Protein Response Promotes Axonal Regeneration Following Peripheral Nerve Injury. Neuroscience 2018; 375:34-48. [PMID: 29438804 DOI: 10.1016/j.neuroscience.2018.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 02/01/2018] [Accepted: 02/02/2018] [Indexed: 01/04/2023]
Abstract
Adult mammalian peripheral neurons have an intrinsic regrowth capacity in response to axonal injury. The induction of calcium ion (Ca2+) oscillations at an injured site is critical for the regulation of regenerative responses. In polarized neurons, distal axonal segments contain a well-developed endoplasmic reticulum (ER) network that is responsible for Ca2+ homeostasis. Although these characteristics implicate the relevance among injury-induced Ca2+ dynamics, axonal ER-derived signaling, and regenerative responses propagated along the axons, the details are not fully understood. In the present study, we found that Ca2+ release from the axonal ER was accelerated in response to injury. Additionally, axonal injury-dependent Ca2+ release from the ER activated unfolded protein response (UPR) signaling at injured sites. Inhibition of axonal UPR signaling led to fragmentation of the axonal ER and disrupted growth cone formation, suggesting that activation of axonal UPR branches following axonal injury promotes regeneration via regulation of ER reconstruction and formation of growth cones. Our studies revealed that local activation of axonal UPR signaling by injury-induced Ca2+ release from the ER is critical for regeneration. These findings provide a new concept for the link between injury-induced signaling at a distant location and regulation of organelle and cytoskeletal formation in the orchestration of axonal regeneration.
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21
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VerPlank JJS, Lokireddy S, Feltri ML, Goldberg AL, Wrabetz L. Impairment of protein degradation and proteasome function in hereditary neuropathies. Glia 2017; 66:379-395. [PMID: 29076578 DOI: 10.1002/glia.23251] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 09/10/2017] [Accepted: 10/09/2017] [Indexed: 01/02/2023]
Abstract
In several neurodegenerative diseases in which misfolded proteins accumulate there is impairment of the ubiquitin proteasome system (UPS). We tested if a similar disruption of proteostasis occurs in hereditary peripheral neuropathies. In sciatic nerves from mouse models of two human neuropathies, Myelin Protein Zero mutation (S63del) and increased copy number (P0 overexpression), polyubiquitinated proteins accumulated, and the overall rates of protein degradation were decreased. 26S proteasomes affinity-purified from sciatic nerves of S63del mice were defective in degradation of peptides and a ubiquitinated protein, unlike proteasomes from P0 overexpression, which appeared normal. Nevertheless, cellular levels of 26S proteasomes were increased in both, through the proteolytic-activation of the transcription factor Nrf1, as occurs in response to proteasome inhibitors. In S63del, increased amounts of the deubiquitinating enzymes USP14, UCH37, and USP5 were associated with proteasomes, the first time this has been reported in a human disease model. Inhibitors of USP14 increased the rate of protein degradation in S63del sciatic nerves and unexpectedly increased the phosphorylation of eIF2α by Perk. Thus, proteasome content, composition and activity are altered in these diseases and USP14 inhibitors have therapeutic potential in S63del neuropathy.
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Affiliation(s)
- Jordan J S VerPlank
- Hunter James Kelly Research Institute and Departments of, Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York.,Harvard Medical School, Boston, Massachusetts
| | | | - M Laura Feltri
- Hunter James Kelly Research Institute and Departments of, Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York
| | | | - Lawrence Wrabetz
- Hunter James Kelly Research Institute and Departments of, Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York
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22
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Abstract
The clinical manifestation of neurodegenerative diseases is initiated by the selective alteration in the functionality of distinct neuronal populations. The pathology of many neurodegenerative diseases includes accumulation of misfolded proteins in the brain. In physiological conditions, the proteostasis network maintains normal protein folding, trafficking and degradation; alterations in this network - particularly disturbances to the function of endoplasmic reticulum (ER) - are thought to contribute to abnormal protein aggregation. ER stress triggers a signalling reaction known as the unfolded protein response (UPR), which induces adaptive programmes that improve protein folding and promote quality control mechanisms and degradative pathways or can activate apoptosis when damage is irreversible. In this Review, we discuss the latest advances in defining the functional contribution of ER stress to brain diseases, including novel evidence that relates the UPR to synaptic function, which has implications for cognition and memory. A complex concept is emerging wherein the consequences of ER stress can differ drastically depending on the disease context and the UPR signalling pathway that is altered. Strategies to target specific components of the UPR using small molecules and gene therapy are in development, and promise interesting avenues for future interventions to delay or stop neurodegeneration.
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23
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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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