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Huang C, Zheng Y, Ji R, Qiao L, Zhang X, Lin H, Liu F, Xu J, Li Y, Zhang Z, Yang X. GPNMB promotes peripheral nerve regeneration by activating the Erk1/2 and Akt pathways via binding Na +/K +-ATPase α1 in Schwann cells. Exp Neurol 2024; 373:114687. [PMID: 38199512 DOI: 10.1016/j.expneurol.2024.114687] [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: 07/28/2023] [Revised: 12/24/2023] [Accepted: 01/06/2024] [Indexed: 01/12/2024]
Abstract
Glycoprotein non-metastatic melanoma protein B (GPNMB) is ubiquitously expressed and has protective effects on the central nervous system. In particular, it is also expressed in the peripheral nervous system (PNS) and upregulated after peripheral nerve injury. However, the role and underlying mechanism of GPNMB in the PNS, especially in peripheral nerve regeneration (PNR), are still unknown and need to be further investigated. In this study, recombinant human GPNMB (rhGPNMB) was injected into a sciatic nerve injury model. It was found that rhGPNMB facilitated the regeneration and functional recovery of the injured sciatic nerve in vivo. Moreover, it was also confirmed that GPNMB activated the Erk1/2 and Akt pathways via binding with Na+/K + -ATPase α1 (NKA α1) and promoted the proliferation and migration of Schwann cells (SCs) and their expression and secretion of neurotrophic factors and neural adhesion molecules in vitro. Our findings demonstrate that GPNMB facilitates PNR through activation of the Erk1/2 and Akt pathways in SCs by binding with NKA α1 and may be a novel strategy for PNR.
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Affiliation(s)
- Chao Huang
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Yani Zheng
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Ruijuan Ji
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Liang Qiao
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Xi Zhang
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Haiyan Lin
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Fang Liu
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Jiajun Xu
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China
| | - Yuquan Li
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China.
| | - Zhiying Zhang
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China.
| | - Xiangqun Yang
- Department of Anatomy, Naval Medical University, #800 Xiangyin Road, Shanghai 200433, China.
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2
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Spiteri AG, Pilkington KR, Wishart CL, Macia L, King NJC. High-Dimensional Methods of Single-Cell Microglial Profiling to Enhance Understanding of Neuropathological Disease. Curr Protoc 2024; 4:e985. [PMID: 38439574 DOI: 10.1002/cpz1.985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Microglia are the innate myeloid cells of the central nervous system (CNS) parenchyma, functionally implicated in almost every defined neuroinflammatory and neurodegenerative disorder. Current understanding of disease pathogenesis for many neuropathologies is limited and/or lacks reliable diagnostic markers, vaccines, and treatments. With the increasing aging of society and rise in neurogenerative diseases, improving our understanding of their pathogenesis is essential. Analysis of microglia from murine disease models provides an investigative tool to unravel disease processes. In many neuropathologies, bone-marrow-derived monocytes are recruited to the CNS, adopting a phenotype similar to that of microglia. This significantly confounds the accurate identification of cell-type-specific functions and downstream therapeutic targeting. The increased capacity to analyze more phenotypic markers using spectral-cytometry-based technologies allows improved separation of microglia from monocyte-derived cells. Full-spectrum profiling enables enhanced marker resolution, time-efficient analysis of >40 fluorescence parameters, and extraction of cellular autofluorescence parameters. Coupling this system with additional cytometric technologies, including cell sorting and high-parameter imaging, can improve the understanding of microglial phenotypes in disease. To this end, we provide detailed, step-by-step protocols for the analysis of murine brain tissue by high-parameter ex vivo cytometric analysis using the Aurora spectral cytometer (Cytek), including best practices for unmixing and autofluorescence extraction, cell sorting for single-cell RNA analysis, and imaging mass cytometry. Together, this provides a toolkit for researchers to comprehensively investigate microglial disease processes at protein, RNA, and spatial levels for the identification of therapeutic targets in neuropathology. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Processing the mouse brain into a single-cell suspension for microglia isolation Basic Protocol 2: Staining single-cell mouse brain suspensions for microglial phenotyping by spectral cytometry Basic Protocol 3: Flow cytometric sorting of mouse microglia for ex vivo analysis Basic Protocol 4: Processing the mouse brain for imaging mass cytometry for spatial microglia analysis.
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Affiliation(s)
- Alanna G Spiteri
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
| | | | - Claire L Wishart
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
| | - Laurence Macia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, Australia
| | - Nicholas J C King
- Viral Immunopathology Laboratory, Infection, Immunity and Inflammation Research Theme, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, Australia
- Sydney Cytometry, The University of Sydney and Centenary Institute, Sydney, Australia
- The University of Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, Australia
- The University of Sydney Nano Institute, The University of Sydney, Sydney, Australia
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3
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Yuan R, Wu C. YTHDF1-mediated sphingosine kinase 2 upregulation alleviates bupivacaine-induced neurotoxicity via the PI3K/AKT axis. Hum Exp Toxicol 2024; 43:9603271231218707. [PMID: 38487884 DOI: 10.1177/09603271231218707] [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] [Indexed: 03/19/2024]
Abstract
BACKGROUND Bupivacaine (BUP), a long-acting local anesthetic, has been widely used in analgesia and anesthesia. However, evidence strongly suggests that excessive application of BUP may lead to neurotoxicity in neurons. Sphingosine kinase 2 (SPHK2) has been reported to exert neuroprotective effects. In this study, we intended to investigate the potential role and mechanism of SPHK2 in BUP-induced neurotoxicity in dorsal root ganglion (DRG) neurons. METHODS DRG neurons were cultured with BUP to simulate BUP-induced neurotoxicity in vitro. CCK-8, LDH, and flow cytometry assays were performed to detect the viability, LDH activity, and apoptosis of DRG neurons. RT-qPCR and western blotting was applied to measure gene and protein expression. Levels. MeRIP-qPCR was applied for quantification of m6A modification. RIP-qPCR was used to analyze the interaction between SPHK2 and YTHDF1. RESULTS SPHK2 expression significantly declined in DRG neurons upon exposure to BUP. BUP challenge substantially reduced the cell viability and increased the apoptosis rate in DRG neurons, which was partly abolished by SPHK2 upregulation. YTHDF1, an N6-methyladenosine (m6A) reader, promoted SPHK2 expression in BUP-treated DRG neurons in an m6A-dependent manner. YTHDF1 knockdown partly eliminated the increase in SPHK2 protein level and the protection against BUP-triggered neurotoxicity in DRG neurons mediated by SPHK2 overexpression. Moreover, SPHK2 activated the PI3K/AKT signaling to protect against BUP-induced cytotoxic effects on DRG neurons. CONCLUSIONS In sum, YTHDF1-mediated SPHK2 upregulation ameliorated BUP-induced neurotoxicity in DRG neurons via promoting activation of the PI3K/AKT signaling pathway.
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Affiliation(s)
- Ru Yuan
- Department of Anesthesiology, Wujin Hospital Affiliated with Jiangsu University, Changzhou, China
- The Wujin Clinical College of Xuzhou Medical University, Changzhou, China
| | - Chunxia Wu
- Department of Anesthesiology, Wujin Hospital Affiliated with Jiangsu University, Changzhou, China
- The Wujin Clinical College of Xuzhou Medical University, Changzhou, China
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4
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Moreno-Rodriguez M, Perez SE, Martinez-Gardeazabal J, Manuel I, Malek-Ahmadi M, Rodriguez-Puertas R, Mufson EJ. Frontal Cortex Lipid Alterations During the Onset of Alzheimer's Disease. J Alzheimers Dis 2024; 98:1515-1532. [PMID: 38578893 DOI: 10.3233/jad-231485] [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] [Indexed: 04/07/2024]
Abstract
Background Although sporadic Alzheimer's disease (AD) is a neurodegenerative disorder of unknown etiology, familial AD is associated with specific gene mutations. A commonality between these forms of AD is that both display multiple pathogenic events including cholinergic and lipid dysregulation. Objective We aimed to identify the relevant lipids and the activity of their related receptors in the frontal cortex and correlating them with cognition during the progression of AD. Methods MALDI-mass spectrometry imaging (MSI) and functional autoradiography was used to evaluate the distribution of phospholipids/sphingolipids and the activity of cannabinoid 1 (CB1), sphingosine 1-phosphate 1 (S1P1), and muscarinic M2/M4 receptors in the frontal cortex (FC) of people that come to autopsy with premortem clinical diagnosis of AD, mild cognitive impairment (MCI), and no cognitive impairment (NCI). Results MALDI-MSI revealed an increase in myelin-related lipids, such as diacylglycerol (DG) 36:1, DG 38:5, and phosphatidic acid (PA) 40:6 in the white matter (WM) in MCI compared to NCI, and a downregulation of WM phosphatidylinositol (PI) 38:4 and PI 38:5 levels in AD compared to NCI. Elevated levels of phosphatidylcholine (PC) 32:1, PC 34:0, and sphingomyelin 38:1 were observed in discrete lipid accumulations in the FC supragranular layers during disease progression. Muscarinic M2/M4 receptor activation in layers V-VI decreased in AD compared to MCI. CB1 receptor activity was upregulated in layers V-VI, while S1P1 was downregulated within WM in AD relative to NCI. Conclusions FC WM lipidomic alterations are associated with myelin dyshomeostasis in prodromal AD, suggesting WM lipid maintenance as a potential therapeutic target for dementia.
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Affiliation(s)
- Marta Moreno-Rodriguez
- Department of Translational Neuroscience, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Sylvia E Perez
- Department of Translational Neuroscience, Barrow Neurological Institute, Phoenix, AZ, USA
| | | | - Ivan Manuel
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country, Leioa, Spain
- Neurodegenerative Diseases, BioBizkaia Health Research Institute, Barakaldo, Spain
| | | | - Rafael Rodriguez-Puertas
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country, Leioa, Spain
- Neurodegenerative Diseases, BioBizkaia Health Research Institute, Barakaldo, Spain
| | - Elliott J Mufson
- Department of Translational Neuroscience, Barrow Neurological Institute, Phoenix, AZ, USA
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Gudi V, Grieb P, Linker RA, Skripuletz T. CDP-choline to promote remyelination in multiple sclerosis: the need for a clinical trial. Neural Regen Res 2023; 18:2599-2605. [PMID: 37449595 DOI: 10.4103/1673-5374.373671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Abstract
Multiple sclerosis is a multifactorial chronic inflammatory disease of the central nervous system that leads to demyelination and neuronal cell death, resulting in functional disability. Remyelination is the natural repair process of demyelination, but it is often incomplete or fails in multiple sclerosis. Available therapies reduce the inflammatory state and prevent clinical relapses. However, therapeutic approaches to increase myelin repair in humans are not yet available. The substance cytidine-5'-diphosphocholine, CDP-choline, is ubiquitously present in eukaryotic cells and plays a crucial role in the synthesis of cellular phospholipids. Regenerative properties have been shown in various animal models of diseases of the central nervous system. We have already shown that the compound CDP-choline improves myelin regeneration in two animal models of multiple sclerosis. However, the results from the animal models have not yet been studied in patients with multiple sclerosis. In this review, we summarise the beneficial effects of CDP-choline on biolipid metabolism and turnover with regard to inflammatory and regenerative processes. We also explain changes in phospholipid and sphingolipid homeostasis in multiple sclerosis and suggest a possible therapeutic link to CDP-choline.
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Affiliation(s)
- Viktoria Gudi
- Department of Neurology, Hannover Medical School, Hannover, Germany
| | - Paweł Grieb
- Department of Experimental Pharmacology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
| | - Ralf A Linker
- Department of Neurology, University Hospital Regensburg, Regensburg, Germany
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6
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Xiao J. Sphingosine 1-Phosphate Lyase in the Developing and Injured Nervous System: a Dichotomy? Mol Neurobiol 2023; 60:6869-6882. [PMID: 37507574 PMCID: PMC10657793 DOI: 10.1007/s12035-023-03524-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023]
Abstract
Sphingosine 1-phosphate lyase (SPL) is the terminal enzyme that controls the degradation of the bioactive lipid sphingosine 1-phosphate (S1P) within an interconnected sphingolipid metabolic network. The unique metabolic position of SPL in maintaining S1P levels implies SPL could be an emerging new therapeutic target. Over the past decade, an evolving effort has been made to unravel the role of SPL in the nervous system; however, to what extent SPL influences the developing and mature nervous system through altering S1P biosynthesis remains opaque. While congenital SPL deletion is associated with deficits in the developing nervous system, the loss of SPL activity in adults appears to be neuroprotective in acquired neurological disorders. The controversial findings concerning SPL's role in the nervous system are further constrained by the current genetic and pharmacological tools. This review attempts to focus on the multi-faceted nature of SPL function in the mammalian nervous systems, implying its dichotomy in the developing and adult central nervous system (CNS). This article also highlights SPL is emerging as a therapeutic molecule that can be selectively targeted to modulate S1P for the treatment of acquired neurodegenerative diseases, raising new questions for future investigation. The development of cell-specific inducible conditional SPL mutants and selective pharmacological tools will allow the precise understanding of SPL's function in the adult CNS, which will aid the development of a new strategy focusing on S1P-based therapies for neuroprotection.
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Affiliation(s)
- Junhua Xiao
- Department of Health Sciences and Biostatistics, School of Health Sciences, Swinburne University of Technology, John Street, Hawthorn, VIC, 3022, Australia.
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7
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Sindi M, Hecker C, Issberner A, Ruck T, Meuth SG, Albrecht P, Dietrich M. S1PR-1/5 modulator RP-101074 shows beneficial effects in a model of central nervous system degeneration. Front Immunol 2023; 14:1234984. [PMID: 37638037 PMCID: PMC10450045 DOI: 10.3389/fimmu.2023.1234984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/18/2023] [Indexed: 08/29/2023] Open
Abstract
Introduction In multiple sclerosis (MS), chronic disability primarily stems from axonal and neuronal degeneration, a condition resistant to conventional immunosuppressive or immunomodulatory treatments. Recent research has indicated that selective sphingosine-1-phosphate receptor S1PR-1 and -5 modulators yield positive effects in progressive MS and mechanistic models of inflammation-driven neurodegeneration and demyelination. Methods In this study, the S1PR-1/-5 modulator RP-101074 was evaluated as a surrogate for ozanimod in the non-inflammatory, primary degenerative animal model of light-induced photoreceptor loss (LI-PRL) in CX3CR1-GFP mice to assess potential neuroprotective effects, independent of its immunomodulatory mechanism of action. Results Prophylactic administration of RP-101074 demonstrated protective effects in the preclinical, non-inflammatory LI-PRL animal model, following a bell-shaped dose-response curve. RP-101074 treatment also revealed activity-modulating effects on myeloid cells, specifically, CX3CR1+ cells, significantly reducing the marked infiltration occurring one week post-irradiation. Treatment with RP-101074 produced beneficial outcomes on both retinal layer thickness and visual function as evidenced by optical coherence tomography (OCT) and optomotor response (OMR) measurements, respectively. Additionally, the myelination status and the quantity of neural stem cells in the optic nerve suggest that RP-101074 may play a role in the activation and/or recruitment of neural stem cells and oligodendrocyte progenitor cells, respectively. Conclusion/Discussion The data from our study suggest that RP-101074 may have a broader role in MS treatment beyond immunomodulation, potentially offering a novel approach to mitigate neurodegeneration, a core contributor to chronic disability in MS.
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Affiliation(s)
- Mustafa Sindi
- Department of Neurology, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Christina Hecker
- Department of Neurology, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Andrea Issberner
- Department of Neurology, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Tobias Ruck
- Department of Neurology, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Sven G. Meuth
- Department of Neurology, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - Philipp Albrecht
- Department of Neurology, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
- Department of Neurology, Maria Hilf Clinics, Mönchengladbach, Germany
| | - Michael Dietrich
- Department of Neurology, Medical Faculty of the Heinrich-Heine University, Düsseldorf, Germany
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8
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Huang S, Ren C, Luo Y, Ding Y, Ji X, Li S. New insights into the roles of oligodendrocytes regulation in ischemic stroke recovery. Neurobiol Dis 2023:106200. [PMID: 37321419 DOI: 10.1016/j.nbd.2023.106200] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/20/2023] [Accepted: 06/12/2023] [Indexed: 06/17/2023] Open
Abstract
Oligodendrocytes (OLs), the myelin-forming cells of the central nervous system, are integral to axonal integrity and function. Hypoxia-ischemia episodes can cause severe damage to these vulnerable cells through excitotoxicity, oxidative stress, inflammation, and mitochondrial dysfunction, leading to axonal dystrophy, neuronal dysfunction, and neurological impairments. OLs damage can result in demyelination and myelination disorders, severely impacting axonal function, structure, metabolism, and survival. Adult-onset stroke, periventricular leukomalacia, and post-stroke cognitive impairment primarily target OLs, making them a critical therapeutic target. Therapeutic strategies targeting OLs, myelin, and their receptors should be given more emphasis to attenuate ischemia injury and establish functional recovery after stroke. This review summarizes recent advances on the function of OLs in ischemic injury, as well as the present and emerging principles that serve as the foundation for protective strategies against OL deaths.
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Affiliation(s)
- Shuangfeng Huang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China; Department of Emergency, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Changhong Ren
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yumin Luo
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China; Institute of Cerebrovascular Diseases Research and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yuchuan Ding
- Department of Neurosurgery, Wayne State University, Detroit, MI, USA
| | - Xunming Ji
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China; Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China.
| | - Sijie Li
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China; Department of Emergency, Xuanwu Hospital, Capital Medical University, Beijing, China; Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.
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9
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Teo JD, Marian OC, Spiteri AG, Nicholson M, Song H, Khor JXY, McEwen HP, Ge A, Sen MK, Piccio L, Fletcher JL, King NJC, Murray SS, Brüning JC, Don AS. Early microglial response, myelin deterioration and lethality in mice deficient for very long chain ceramide synthesis in oligodendrocytes. Glia 2023; 71:1120-1141. [PMID: 36583573 PMCID: PMC10952316 DOI: 10.1002/glia.24329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 11/05/2022] [Accepted: 12/15/2022] [Indexed: 12/31/2022]
Abstract
The sphingolipids galactosylceramide (GalCer), sulfatide (ST) and sphingomyelin (SM) are essential for myelin stability and function. GalCer and ST are synthesized mostly from C22-C24 ceramides, generated by Ceramide Synthase 2 (CerS2). To clarify the requirement for C22-C24 sphingolipid synthesis in myelin biosynthesis and stability, we generated mice lacking CerS2 specifically in myelinating cells (CerS2ΔO/ΔO ). At 6 weeks of age, normal-appearing myelin had formed in CerS2ΔO/ΔO mice, however there was a reduction in myelin thickness and the percentage of myelinated axons. Pronounced loss of C22-C24 sphingolipids in myelin of CerS2ΔO/ΔO mice was compensated by greatly increased levels of C18 sphingolipids. A distinct microglial population expressing high levels of activation and phagocytic markers such as CD64, CD11c, MHC class II, and CD68 was apparent at 6 weeks of age in CerS2ΔO/ΔO mice, and had increased by 10 weeks. Increased staining for denatured myelin basic protein was also apparent in 6-week-old CerS2ΔO/ΔO mice. By 16 weeks, CerS2ΔO/ΔO mice showed pronounced myelin atrophy, motor deficits, and axon beading, a hallmark of axon stress. 90% of CerS2ΔO/ΔO mice died between 16 and 26 weeks of age. This study highlights the importance of sphingolipid acyl chain length for the structural integrity of myelin, demonstrating how a modest reduction in lipid chain length causes exposure of a denatured myelin protein epitope and expansion of phagocytic microglia, followed by axon pathology, myelin degeneration, and motor deficits. Understanding the molecular trigger for microglial activation should aid the development of therapeutics for demyelinating and neurodegenerative diseases.
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Affiliation(s)
- Jonathan D. Teo
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Oana C. Marian
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Alanna G. Spiteri
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Madeline Nicholson
- Department of Anatomy and PhysiologyThe University of MelbourneParkvilleVictoriaAustralia
| | - Huitong Song
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Jasmine X. Y. Khor
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Holly P. McEwen
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Anjie Ge
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Monokesh K. Sen
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Laura Piccio
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
- Department of NeurologyWashington University School of MedicineSt LouisMissouriUSA
| | - Jessica L. Fletcher
- Menzies Institute for Medical ResearchThe University of TasmaniaHobartTasmaniaAustralia
| | - Nicholas J. C. King
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Simon S. Murray
- Department of Anatomy and PhysiologyThe University of MelbourneParkvilleVictoriaAustralia
| | | | - Anthony S. Don
- Charles Perkins Centre and School of Medical SciencesThe University of SydneyCamperdownNew South WalesAustralia
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10
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Marian OC, Teo JD, Lee JY, Song H, Kwok JB, Landin-Romero R, Halliday G, Don AS. Disrupted myelin lipid metabolism differentiates frontotemporal dementia caused by GRN and C9orf72 gene mutations. Acta Neuropathol Commun 2023; 11:52. [PMID: 36967384 PMCID: PMC10041703 DOI: 10.1186/s40478-023-01544-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 03/12/2023] [Indexed: 03/29/2023] Open
Abstract
Heterozygous mutations in the GRN gene and hexanucleotide repeat expansions in C9orf72 are the two most common genetic causes of Frontotemporal Dementia (FTD) with TDP-43 protein inclusions. The triggers for neurodegeneration in FTD with GRN (FTD-GRN) or C9orf72 (FTD-C9orf72) gene abnormalities are unknown, although evidence from mouse and cell culture models suggests that GRN mutations disrupt lysosomal lipid catabolism. To determine how brain lipid metabolism is affected in familial FTD with TDP-43 inclusions, and how this is related to myelin and lysosomal markers, we undertook comprehensive lipidomic analysis, enzyme activity assays, and western blotting on grey and white matter samples from the heavily-affected frontal lobe and less-affected parietal lobe of FTD-GRN cases, FTD-C9orf72 cases, and age-matched neurologically-normal controls. Substantial loss of myelin-enriched sphingolipids (sulfatide, galactosylceramide, sphingomyelin) and myelin proteins was observed in frontal white matter of FTD-GRN cases. A less-pronounced, yet statistically significant, loss of sphingolipids was also observed in FTD-C9orf72. FTD-GRN was distinguished from FTD-C9orf72 and control cases by increased acylcarnitines in frontal grey matter and marked accumulation of cholesterol esters in both frontal and parietal white matter, indicative of myelin break-down. Both FTD-GRN and FTD-C9orf72 cases showed significantly increased lysosomal and phagocytic protein markers, however galactocerebrosidase activity, required for lysosomal catabolism of galactosylceramide and sulfatide, was selectively increased in FTD-GRN. We conclude that both C9orf72 and GRN mutations are associated with disrupted lysosomal homeostasis and white matter lipid loss, but GRN mutations cause a more pronounced disruption to myelin lipid metabolism. Our findings support the hypothesis that hyperactive myelin lipid catabolism is a driver of gliosis and neurodegeneration in FTD-GRN. Since FTD-GRN is associated with white matter hyperintensities by MRI, our data provides important biochemical evidence supporting the use of MRI measures of white matter integrity in the diagnosis and management of FTD.
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Affiliation(s)
- Oana C Marian
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
- School of Medical Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Jonathan D Teo
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
- School of Medical Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Jun Yup Lee
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
- School of Medical Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Huitong Song
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
- School of Medical Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - John B Kwok
- School of Medical Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia
- Brain and Mind Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Ramon Landin-Romero
- Brain and Mind Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
- School of Health Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Glenda Halliday
- School of Medical Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia
- Brain and Mind Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Anthony S Don
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia.
- School of Medical Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia.
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Leo H, Kipp M. Remyelination in Multiple Sclerosis: Findings in the Cuprizone Model. Int J Mol Sci 2022; 23:ijms232416093. [PMID: 36555733 PMCID: PMC9783537 DOI: 10.3390/ijms232416093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Remyelination therapies, which are currently under development, have a great potential to delay, prevent or even reverse disability in multiple sclerosis patients. Several models are available to study the effectiveness of novel compounds in vivo, among which is the cuprizone model. This model is characterized by toxin-induced demyelination, followed by endogenous remyelination after cessation of the intoxication. Due to its high reproducibility and ease of use, this model enjoys high popularity among various research and industrial groups. In this review article, we will summarize recent findings using this model and discuss the potential of some of the identified compounds to promote remyelination in multiple sclerosis patients.
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Affiliation(s)
| | - Markus Kipp
- Correspondence: ; Tel.: +49-(0)-381-494-8400
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