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Michailidou I, Vreijling J, Rumpf M, Loos M, Koopmans B, Vlek N, Straat N, Agaser C, Kuipers TB, Mei H, Baas F, Fluiter K. The systemic inhibition of the terminal complement system reduces neuroinflammation but does not improve motor function in mouse models of CMT1A with overexpressed PMP22. CURRENT RESEARCH IN NEUROBIOLOGY 2023; 4:100077. [PMID: 36926597 PMCID: PMC10011818 DOI: 10.1016/j.crneur.2023.100077] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 12/13/2022] [Accepted: 01/27/2023] [Indexed: 02/07/2023] Open
Abstract
Charcot-Marie-Tooth disease type 1A (CMT1A) is the most prevalent hereditary demyelinating neuropathy. This autosomal, dominantly inherited disease is caused by a duplication on chromosome 17p which includes the peripheral myelin protein 22 (PMP22) gene. There is clinical evidence that the disability in CMT1A is to a large extend due to axonal damage rather than demyelination. Over-expression of PMP22 is recently thought to impede cholesterol trafficking causing a total shutdown of local cholesterol and lipid synthesis in the Schwann cells, thus disturbing their ability to remyelinate. But there is a large variety in disease burden between CMT1A patients with the same genetic defect, indicating the presence of modifying factors that affect disease severity. One of these potential factors is the immune system. Several reports have described patients with co-occurrence of CMT1A with chronic inflammatory demyelinating disease or Guillain-Barré syndrome. We have previously shown in multiple animal models that the innate immune system and specifically the terminal complement system is a driver of inflammatory demyelination. To test the contribution of the terminal complement system to neuroinflammation and disease progression in CMT1A, we inhibited systemic complement C6 in two transgenic mouse models for CMT1A, the C3-PMP22 and C3-PMP22 c-JunP0Cre models. Both models over-express human PMP22, and one (C3-PMP22 c-JunP0Cre) also has a Schwann cell-specific knockout of c-Jun, a crucial regulator of myelination controlling autophagy. We found that systemic inhibition of C6 using antisense oligonucleotides affects the neuroinflammation, Rho GTPase and ERK/MAPK signalling pathways in the CMT1A mouse models. The cholesterol synthesis pathway remained unaffected. Analysis of motor function during treatment with C6 antisense oligonucleotides did not reveal any significant improvement in the CMT1A mouse models. This study shows that the contribution of the terminal complement system to progressive loss of motor function in the CMT1A mouse models tested is limited.
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Affiliation(s)
- Iliana Michailidou
- Dept of Clinical Genetics, LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Jeroen Vreijling
- Dept of Clinical Genetics, LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Matthijs Rumpf
- Dept of Clinical Genetics, LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Maarten Loos
- Sylics (Synaptologics B.V.), Bilthoven, the Netherlands
| | | | - Nina Vlek
- Sylics (Synaptologics B.V.), Bilthoven, the Netherlands
| | - Nina Straat
- Sylics (Synaptologics B.V.), Bilthoven, the Netherlands
| | - Cedrick Agaser
- Sequencing Analysis Support Core, Department of Biomedical Data Sciences LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Thomas B Kuipers
- Sequencing Analysis Support Core, Department of Biomedical Data Sciences LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Hailiang Mei
- Sequencing Analysis Support Core, Department of Biomedical Data Sciences LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Frank Baas
- Dept of Clinical Genetics, LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Kees Fluiter
- Dept of Clinical Genetics, LUMC, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
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Lin WC, Gowdy KM, Madenspacher JH, Zemans RL, Yamamoto K, Lyons-Cohen M, Nakano H, Janardhan K, Williams CJ, Cook DN, Mizgerd JP, Fessler MB. Epithelial membrane protein 2 governs transepithelial migration of neutrophils into the airspace. J Clin Invest 2020; 130:157-170. [PMID: 31550239 DOI: 10.1172/jci127144] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 09/18/2019] [Indexed: 02/06/2023] Open
Abstract
Whether respiratory epithelial cells regulate the final transit of extravasated neutrophils into the inflamed airspace or are a passive barrier is poorly understood. Alveolar epithelial type 1 (AT1) cells, best known for solute transport and gas exchange, have few established immune roles. Epithelial membrane protein 2 (EMP2), a tetraspan protein that promotes recruitment of integrins to lipid rafts, is highly expressed in AT1 cells but has no known function in lung biology. Here, we show that Emp2-/- mice exhibit reduced neutrophil influx into the airspace after a wide range of inhaled exposures. During bacterial pneumonia, Emp2-/- mice had attenuated neutrophilic lung injury and improved survival. Bone marrow chimeras, intravital neutrophil labeling, and in vitro assays suggested that defective transepithelial migration of neutrophils into the alveolar lumen occurs in Emp2-/- lungs. Emp2-/- AT1 cells had dysregulated surface display of multiple adhesion molecules, associated with reduced raft abundance. Epithelial raft abundance was dependent upon putative cholesterol-binding motifs in EMP2, whereas EMP2 supported adhesion molecule display and neutrophil transmigration through suppression of caveolins. Taken together, we propose that EMP2-dependent membrane organization ensures proper display on AT1 cells of a suite of proteins required to instruct paracellular neutrophil traffic into the alveolus.
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Affiliation(s)
- Wan-Chi Lin
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Kymberly M Gowdy
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Jennifer H Madenspacher
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Rachel L Zemans
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Kazuko Yamamoto
- Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA.,Second Department of Internal Medicine, Nagasaki University Hospital, Nagasaki, Japan.,Department of Clinical Research Center, National Hospital Organization Nagasaki Medical Center, Omura, Japan
| | - Miranda Lyons-Cohen
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Hideki Nakano
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Kyathanahalli Janardhan
- Cellular & Molecular Pathology Branch, National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.,Integrated Laboratory Systems Inc., Research Triangle Park, North Carolina, USA
| | - Carmen J Williams
- Reproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Donald N Cook
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Joseph P Mizgerd
- Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Michael B Fessler
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
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Zhou Y, Borchelt D, Bauson JC, Fazio S, Miles JR, Tavori H, Notterpek L. Subcellular diversion of cholesterol by gain- and loss-of-function mutations in PMP22. Glia 2020; 68:2300-2315. [PMID: 32511821 DOI: 10.1002/glia.23840] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 03/22/2020] [Accepted: 04/24/2020] [Indexed: 12/13/2022]
Abstract
Abnormalities of the peripheral myelin protein 22 (PMP22) gene, including duplication, deletion and point mutations are a major culprit in Type 1 Charcot-Marie-Tooth (CMT) diseases. The complete absence of PMP22 alters cholesterol metabolism in Schwann cells, which likely contributes to myelination deficits. Here, we examined the subcellular trafficking of cholesterol in distinct models of PMP22-linked neuropathies. In Schwann cells from homozygous Trembler J (TrJ) mice carrying a Leu16Pro mutation, cholesterol was retained with TrJ-PMP22 in the Golgi, alongside a corresponding reduction in its plasma membrane level. PMP22 overexpression, which models CMT1A caused by gene duplication, triggered cholesterol sequestration to lysosomes, and reduced ATP-binding cassette transporter-dependent cholesterol efflux. Conversely, lysosomal targeting of cholesterol by U18666A treatment increased wild type (WT)-PMP22 levels in lysosomes. Mutagenesis of a cholesterol recognition motif, or CRAC domain, in human PMP22 lead to increased levels of PMP22 in the ER and Golgi compartments, along with higher cytosolic, and lower membrane-associated cholesterol. Importantly, cholesterol trafficking defects observed in PMP22-deficient Schwann cells were rescued by WT but not CRAC-mutant-PMP22. We also observed that myelination deficits in dorsal root ganglia explants from heterozygous PMP22-deficient mice were improved by cholesterol supplementation. Collectively, these findings indicate that PMP22 is critical in cholesterol metabolism, and this mechanism is likely a contributing factor in PMP22-linked hereditary neuropathies. Our results provide a basis for understanding how altered expression of PMP22 impacts cholesterol metabolism.
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Affiliation(s)
- Ye Zhou
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - David Borchelt
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Jodi C Bauson
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
| | - Sergio Fazio
- Department of Medicine, Knight Cardiovascular Institute, Center for Preventive Cardiology, Oregon Health and Science University, Oregon, Portland, USA
| | - Joshua R Miles
- Department of Medicine, Knight Cardiovascular Institute, Center for Preventive Cardiology, Oregon Health and Science University, Oregon, Portland, USA
| | - Hagai Tavori
- Department of Medicine, Knight Cardiovascular Institute, Center for Preventive Cardiology, Oregon Health and Science University, Oregon, Portland, USA
| | - Lucia Notterpek
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA.,Department of Neurology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA
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Zhou Y, Bazick H, Miles JR, Fethiere AI, Salihi MOA, Fazio S, Tavori H, Notterpek L. A neutral lipid-enriched diet improves myelination and alleviates peripheral nerve pathology in neuropathic mice. Exp Neurol 2019; 321:113031. [DOI: 10.1016/j.expneurol.2019.113031] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 07/27/2019] [Accepted: 08/02/2019] [Indexed: 12/13/2022]
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Zhou Y, Miles JR, Tavori H, Lin M, Khoshbouei H, Borchelt DR, Bazick H, Landreth GE, Lee S, Fazio S, Notterpek L. PMP22 Regulates Cholesterol Trafficking and ABCA1-Mediated Cholesterol Efflux. J Neurosci 2019; 39:5404-5418. [PMID: 31061090 PMCID: PMC6607759 DOI: 10.1523/jneurosci.2942-18.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 04/22/2019] [Accepted: 04/26/2019] [Indexed: 12/21/2022] Open
Abstract
The absence of functional peripheral myelin protein 22 (PMP22) is associated with shortened lifespan in rodents and severe peripheral nerve myelin abnormalities in several species including humans. Schwann cells and nerves from PMP22 knock-out (KO) mice show deranged cholesterol distribution and aberrant lipid raft morphology, supporting an unrecognized role for PMP22 in cellular lipid metabolism. To examine the mechanisms underlying these abnormalities, we studied Schwann cells and nerves from male and female PMP22 KO mice. Whole-cell current-clamp recordings in cultured Schwann cells revealed increased membrane capacitance and decreased membrane resistance in the absence of PMP22, which was consistent with a reduction in membrane cholesterol. Nerves from PMP22-deficient mice contained abnormal lipid droplets, with both mRNA and protein levels of apolipoprotein E (apoE) and ATP-binding cassette transporter A1 (ABCA1) being highly upregulated. Despite the upregulation of ABCA1 and apoE, the absence of PMP22 resulted in reduced localization of the transporter to the cell membrane and diminished secretion of apoE. The absence of PMP22 also impaired ABCA1-mediated cholesterol efflux capacity. In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant. In wild-type samples, double immunolabeling identified overlapping distribution of PMP22 and ABCA1 at the Schwann cell plasma membrane and the two proteins were coimmunoprecipitated from Schwann cell and nerve lysates. Together, these results reveal a novel role for PMP22 in regulating lipid metabolism and cholesterol trafficking through functional interaction with the cholesterol efflux regulatory protein ABCA1.SIGNIFICANCE STATEMENT Understanding the subcellular events that underlie abnormal myelin formation in hereditary neuropathies is critical for advancing therapy development. Peripheral myelin protein 22 (PMP22) is an essential peripheral myelin protein because its genetic abnormalities account for ∼80% of hereditary neuropathies. Here, we demonstrate that in the absence of PMP22, the cellular and electrophysiological properties of the Schwann cells' plasma membrane are altered and cholesterol trafficking and lipid homeostasis are perturbed. The molecular mechanisms for these abnormalities involve a functional interplay among PMP22, cholesterol, apolipoprotein E, and the major cholesterol-efflux transporter protein ATP-binding cassette transporter A1 (ABCA1). These findings establish a critical role for PMP22 in the maintenance of cholesterol homeostasis in Schwann cells.
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Affiliation(s)
| | - Joshua R Miles
- Department of Medicine
- Department of Physiology and Pharmacology, Knight Cardiovascular Institute, Center of Preventive Cardiology, Oregon Health & Science University, Portland, Oregon 27332, and
| | - Hagai Tavori
- Department of Medicine
- Department of Physiology and Pharmacology, Knight Cardiovascular Institute, Center of Preventive Cardiology, Oregon Health & Science University, Portland, Oregon 27332, and
| | | | | | | | | | - Gary E Landreth
- Department of Neurosciences, Indiana University, Indianapolis, Indiana 46202
| | | | - Sergio Fazio
- Department of Medicine
- Department of Physiology and Pharmacology, Knight Cardiovascular Institute, Center of Preventive Cardiology, Oregon Health & Science University, Portland, Oregon 27332, and
| | - Lucia Notterpek
- Department of Neuroscience,
- Department of Neurology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610
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Abstract
Haploinsufficiency of peripheral myelin protein 22 (PMP22) causes hereditary neuropathy with liability to pressure palsies, a peripheral nerve lesion induced by minimal trauma or compression. As PMP22 is localized to cholesterol-enriched membrane domains that are closely linked with the underlying actin network, we asked whether the myelin instability associated with PMP22 deficiency could be mediated by involvement of the protein in actin-dependent cellular functions and/or lipid raft integrity. In peripheral nerves and cells from mice with PMP22 deletion, we assessed the organization of filamentous actin (F-actin), and actin-dependent cellular functions. Using in vitro models, we discovered that, in the absence of PMP22, the migration and adhesion capacity of Schwann cells and fibroblasts are similarly impaired. Furthermore, PMP22-deficient Schwann cells produce shortened myelin internodes, and display compressed axial cell length and collapsed lamellipodia. During early postnatal development, F-actin-enriched Schmidt-Lanterman incisures do not form properly in nerves from PMP22(-/-) mice, and the expression and localization of molecules associated with uncompacted myelin domains and lipid rafts, including flotillin-1, cholesterol, and GM1 ganglioside, are altered. In addition, we identified changes in the levels and distribution of cholesterol and ApoE when PMP22 is absent. Significantly, cholesterol supplementation of the culture medium corrects the elongation and migration deficits of PMP22(-/-) Schwann cells, suggesting that the observed functional impairments are directly linked with cholesterol deficiency of the plasma membrane. Our findings support a novel role for PMP22 in the linkage of the actin cytoskeleton with the plasma membrane, likely through regulating the cholesterol content of lipid rafts.
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Sedzik J, Jastrzebski JP, Grandis M. Glycans of myelin proteins. J Neurosci Res 2014; 93:1-18. [PMID: 25213400 DOI: 10.1002/jnr.23462] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 06/19/2014] [Accepted: 07/07/2014] [Indexed: 01/04/2023]
Abstract
Human P0 is the main myelin glycoprotein of the peripheral nervous system. It can bind six different glycans, all linked to Asn(93) , the unique glycosylation site. Other myelin glycoproteins, also with a single glycosylation site (PMP22 at Asn(36) , MOG at Asn(31) ), bind only one glycan. The MAG has 10 glycosylation sites; the glycoprotein OMgp has 11 glycosylation sites. Aside from P0, no comprehensive data are available on other myelin glycoproteins. Here we review and analyze all published data on the physicochemical structure of the glycans linked to P0, PMP22, MOG, and MAG. Most data concern bovine P0, whose glycan moieties have an MW ranging from 1,294.56 Da (GP3) to 2,279.94 Da (GP5). The pI of glycosylated P0 protein varies from pH 9.32 to 9.46. The most charged glycan is MS2 containing three sulfate groups and one glucuronic acid; whereas the least charged one is the BA2 residue. All glycans contain one fucose and one galactose. The most mannose rich are the glycans MS2 and GP4, each of them has four mannoses; OPPE1 contains five N-acetylglucosamines and one sulfated glucuronic acid; GP4 contains one sialic acid. Furthermore, human P0 variants causing both gain and loss of glycosylation have been described and cause peripheral neuropathies with variable clinical severity. In particular, the substitution T(95) →M is a very common in Europe and is associated with a late-onset axonal neuropathy. Although peripheral myelin is made up largely of glycoproteins, mutations altering glycosylation have been described only in P0. This attractive avenue of research requires further study.
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Affiliation(s)
- Jan Sedzik
- Royal Institute of Technology, Department of Chemical Engineering, Protein Crystallization Facility, Stockholm, Sweden; National Institute of Physiological Sciences, Department of Neuroscience and Bioinformatics, Okazaki, Japan
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