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The glycosyltransferase EXTL2 promotes proteoglycan deposition and injurious neuroinflammation following demyelination.

Accepted version
Peer-reviewed

Type

Article

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Authors

Pu, Annie 
Mishra, Manoj K 
Dong, Yifei 
Ghorbanigazar, Samira 
Stephenson, Erin L 

Abstract

BACKGROUND: Chondroitin sulfate proteoglycans (CSPGs) are potent inhibitors of axonal regrowth and remyelination. More recently, they have also been highlighted as a modulator of macrophage infiltration into the central nervous system in experimental autoimmune encephalomyelitis, an inflammatory model of multiple sclerosis. METHODS: We interrogated results from single nucleotide polymorphisms (SNPs) lying in or close to genes regulating CSPG metabolism in the summary results from two publicly available systematic studies of multiple sclerosis (MS) genetics. A demyelinating injury model in the spinal cord of exostosin-like 2 deficient  (EXTL2-/-) mice was used to investigate the effects of dysregulation of EXTL2 on remyelination. Cell cultures of bone marrow-derived macrophages and primary oligodendrocyte precursor cells and neurons were supplemented with purified CSPGs or conditioned media to assess potential mechanisms of action. RESULTS: The strongest evidence for genetic association was seen for SNPs mapping to the region containing the glycosyltransferase exostosin-like 2 (EXTL2), an enzyme that normally suppresses CSPG biosynthesis. Six of these SNPs showed genome-wide significant evidence for association in one of the studies with concordant and nominally significant effects in the second study. We then went on to show that a demyelinating injury to the spinal cord of EXTL2-/- mice resulted in excessive deposition of CSPGs in the lesion area. EXTL2-/- mice had exacerbated axonal damage and myelin disruption relative to wild-type mice, and increased representation of microglia/macrophages within lesions. In tissue culture, activated bone marrow-derived macrophages from EXTL2-/- mice overproduce tumor necrosis factor α (TNFα) and matrix metalloproteinases (MMPs). CONCLUSIONS: These results emphasize CSPGs as a prominent modulator of neuroinflammation and they highlight CSPGs accumulating in lesions in promoting axonal injury.

Description

Keywords

CSPG, Demyelination, EXTL2, Inflammation, Multiple sclerosis, Oligodendrocyte, Animals, Chondroitin Sulfate Proteoglycans, Demyelinating Diseases, Female, Humans, Inflammation, Macrophages, Male, Membrane Proteins, Mice, Mice, Inbred C57BL, Mice, Knockout, Multiple Sclerosis, N-Acetylglucosaminyltransferases, Polymorphism, Single Nucleotide

Journal Title

J Neuroinflammation

Conference Name

Journal ISSN

1742-2094
1742-2094

Volume Title

17

Publisher

Springer Science and Business Media LLC

Rights

All rights reserved
Sponsorship
Canadian Institutes of Health Sciences Alberta/Novartis Translational Research Fund Multiple Sclerosis Society of Canada