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Early microglial response, myelin deterioration and lethality in mice deficient for very long chain ceramide synthesis in oligodendrocytes

Citation

Teo, JD and Marian, OC and Spiteri, AG and Nicholson, M and Song, H and Khor, JXY and McEwen, HP and Ge, A and Sen, MK and Piccio, L and Fletcher, JL and King, NJC and Murray, SS and Bruning, JC and Don, AS, Early microglial response, myelin deterioration and lethality in mice deficient for very long chain ceramide synthesis in oligodendrocytes, Glia, 71, (4) pp. 1120-1141. ISSN 0894-1491 (2022) [Refereed Article]


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Copyright Statement

© 2022 The Authors. GLIA published by Wiley Periodicals LLC. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License, https://creativecommons.org/licenses/by-nc-nd/4.0/ which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

DOI: doi:10.1002/glia.24329

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.

Item Details

Item Type:Refereed Article
Keywords:ceramide, CERS2, demyelination, lipid, microglia, myelin, sphingolipid
Research Division:Biomedical and Clinical Sciences
Research Group:Neurosciences
Research Field:Central nervous system
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the biomedical and clinical sciences
UTAS Author:Fletcher, JL (Dr Jessica Fletcher)
ID Code:155418
Year Published:2022
Deposited By:Menzies Institute for Medical Research
Deposited On:2023-02-20
Last Modified:2023-03-21
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