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Glia. 2016 Aug;64(8):1314-30. doi: 10.1002/glia.23004. Epub 2016 May 9.

Polysialylation and lipopolysaccharide-induced shedding of E-selectin ligand-1 and neuropilin-2 by microglia and THP-1 macrophages.

Author information

1
Institute for Cellular Chemistry, Hannover Medical School, Carl-Neuberg-Straße 1, 30625, Hannover, Germany.
2
Center for Systems Neuroscience (ZSN), Hannover, Bünteweg 2, 30559, Hannover, Germany.
3
Institute of Reconstructive Neurobiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany.

Abstract

Microglia are tissue macrophages and mediators of innate immune responses in the brain. The protein-modifying glycan polysialic acid (polySia) is implicated in modulating microglia activity. Cultured murine microglia maintain a pool of Golgi-confined polySia, which is depleted in response to lipopolysaccharide (LPS)-induced activation. Polysialylated neuropilin-2 (polySia-NRP2) contributes to this pool but further polySia protein carriers have remained elusive. Here, we use organotypic brain slice cultures to demonstrate that injury-induced activation of microglia initiates Golgi-confined polySia expression in situ. An unbiased glycoproteomic approach with stem cell-derived microglia identifies E-selectin ligand-1 (ESL-1) as a novel polySia acceptor. Together with polySia-NRP2, polySia-ESL-1 is also detected in primary cultured microglia, in brain slice cultures and in phorbol ester-induced THP-1 macrophages. Induction of stem cell-derived microglia, activated microglia in brain slice cultures and THP-1 macrophages by LPS, but not interleukin-4, causes polySia depletion and, as shown for stem cell-derived microglia, a metalloproteinase-dependent release of polySia-ESL-1 and polySia-NRP2. Moreover, soluble polySia attenuates LPS-induced production of nitric oxide and proinflammatory cytokines. Thus, shedding of polySia-ESL-1 and polySia-NRP2 after LPS-induced activation of microglia and THP-1 macrophages may constitute a mechanism for negative feedback regulation. GLIA 2016 GLIA 2016;64:1314-1330.

KEYWORDS:

GLG1; PSA-NCAM; immunomodulation; microglia activation; protein glycosylation

PMID:
27159043
DOI:
10.1002/glia.23004
[Indexed for MEDLINE]

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