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Dustin E, McQuiston AR, Honke K, Palavicini JP, Han X, Dupree JL. Adult-onset depletion of sulfatide leads to axonal degeneration with relative myelin sparing. Glia 2023; 71:2285-2303. [PMID: 37283058 PMCID: PMC11007682 DOI: 10.1002/glia.24423] [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: 12/16/2022] [Revised: 05/10/2023] [Accepted: 05/12/2023] [Indexed: 06/08/2023]
Abstract
3-O-sulfogalactosylceramide (sulfatide) constitutes a class of sphingolipids that comprise about 4% of myelin lipids in the central nervous system. Previously, our group characterized a mouse with sulfatide's synthesizing enzyme, cerebroside sulfotransferase (CST), constitutively disrupted. Using these mice, we demonstrated that sulfatide is required for establishment and maintenance of myelin, axoglial junctions, and axonal domains and that sulfatide depletion results in structural pathologies commonly observed in Multiple Sclerosis (MS). Interestingly, sulfatide is reduced in regions of normal appearing white matter (NAWM) of MS patients. Sulfatide reduction in NAWM suggests depletion occurs early in disease development and consistent with functioning as a driving force of disease progression. To closely model MS, an adult-onset disease, our lab generated a "floxed" CST mouse and mated it against the PLP-creERT mouse, resulting in a double transgenic mouse that provides temporal and cell-type specific ablation of the Cst gene (Gal3st1). Using this mouse, we demonstrate adult-onset sulfatide depletion has limited effects on myelin structure but results in the loss of axonal integrity including deterioration of domain organization accompanied by axonal degeneration. Moreover, structurally preserved myelinated axons progressively lose the ability to function as myelinated axons, indicated by the loss of the N1 peak. Together, our findings indicate that sulfatide depletion, which occurs in the early stages of MS progression, is sufficient to drive the loss of axonal function independent of demyelination and that axonal pathology, which is responsible for the irreversible loss of neuronal function that is prevalent in MS, may occur earlier than previously recognized.
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Affiliation(s)
- E Dustin
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
- Research Service, Central Virginia Veterans Affairs Health Care Systems, Richmond, Virginia, USA
| | - A R McQuiston
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - K Honke
- Department of Biochemistry, Kochi University Medical School, Kochi, Japan
| | - J P Palavicini
- Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - X Han
- Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - J L Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
- Research Service, Central Virginia Veterans Affairs Health Care Systems, Richmond, Virginia, USA
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Spencer SA, Suárez-Pozos E, Verdugo JS, Wang H, Afshari FS, Li G, Manam S, Yasuda D, Ortega A, Lister JA, Ishii S, Zhang Y, Fuss B. Lysophosphatidic acid signaling via LPA 6 : A negative modulator of developmental oligodendrocyte maturation. J Neurochem 2022; 163:478-499. [PMID: 36153691 PMCID: PMC9772207 DOI: 10.1111/jnc.15696] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 01/14/2023]
Abstract
The developmental process of central nervous system (CNS) myelin sheath formation is characterized by well-coordinated cellular activities ultimately ensuring rapid and synchronized neural communication. During this process, myelinating CNS cells, namely oligodendrocytes (OLGs), undergo distinct steps of differentiation, whereby the progression of earlier maturation stages of OLGs represents a critical step toward the timely establishment of myelinated axonal circuits. Given the complexity of functional integration, it is not surprising that OLG maturation is controlled by a yet fully to be defined set of both negative and positive modulators. In this context, we provide here first evidence for a role of lysophosphatidic acid (LPA) signaling via the G protein-coupled receptor LPA6 as a negative modulatory regulator of myelination-associated gene expression in OLGs. More specifically, the cell surface accessibility of LPA6 was found to be restricted to the earlier maturation stages of differentiating OLGs, and OLG maturation was found to occur precociously in Lpar6 knockout mice. To further substantiate these findings, a novel small molecule ligand with selectivity for preferentially LPA6 and LPA6 agonist characteristics was functionally characterized in vitro in primary cultures of rat OLGs and in vivo in the developing zebrafish. Utilizing this approach, a negative modulatory role of LPA6 signaling in OLG maturation could be corroborated. During development, such a functional role of LPA6 signaling likely serves to ensure timely coordination of circuit formation and myelination. Under pathological conditions as seen in the major human demyelinating disease multiple sclerosis (MS), however, persistent LPA6 expression and signaling in OLGs can be seen as an inhibitor of myelin repair. Thus, it is of interest that LPA6 protein levels appear elevated in MS brain samples, thereby suggesting that LPA6 signaling may represent a potential new druggable pathway suitable to promote myelin repair in MS.
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Affiliation(s)
- Samantha A Spencer
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Edna Suárez-Pozos
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Jazmín Soto Verdugo
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Huiqun Wang
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia, USA
| | - Fatemah S Afshari
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Guo Li
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia, USA
| | - Susmita Manam
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Daisuke Yasuda
- Department of Immunology, Akita University Graduate School of Medicine, Akita, Japan
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - James A Lister
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Satoshi Ishii
- Department of Immunology, Akita University Graduate School of Medicine, Akita, Japan
| | - Yan Zhang
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia, USA
| | - Babette Fuss
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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