Journal of Alzheimer's Disease
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Home > Astrocytes release HspB1 in response to amyloid-β exposure in vitro.

TitleAstrocytes release HspB1 in response to amyloid-β exposure in vitro.
Publication TypeJournal Article
Year of Publication2016
AuthorsNafar, F, J Williams, B, Mearow, KM
JournalJ Alzheimers Dis
Volume49
Issue1
Pagination251-63
Date Published2016
ISSN1875-8908
KeywordsAmyloid beta-Peptides, Animals, Astrocytes, Cells, Cultured, HSP27 Heat-Shock Proteins, Protein Transport, Rats
Abstract

Although heat shock proteins are thought to function primarily as intracellular chaperones, the release and potential extracellular functions of heat shock proteins have been the focus of an increasing number of studies. Our particular interest is HspB1 (Hsp25/27) and as astrocytes are an in vivo source of HspB1 it is a reasonable possibility they could release HspB1 in response to local stresses. Using primary cultures of rat cortical astrocytes, we investigated the extracellular release of HspB1 with exposure to amyloid-β (Aβ). In order to assess potential mechanisms of release, we cotreated the cells with compounds that can modulate protein secretion including Brefeldin A, Methyl β-cyclodextrin, and MAP kinase inhibitors. Exposure to Aβ (0.1, 1.0, 2.0 μM) for 24-48 h resulted in a selective release of HspB1 that was insensitive to BFA treatment; none of the other inhibitors had any detectable influence. Protease protection assays indicated that some of the released HspB1 was associated with a membrane bound fraction, and analysis of exosomal preparations indicated the presence of HspB1 in exosomes. Finally, immunoprecipitation experiments demonstrated that the extracellular HspB1 was able to interact with extracellular Aβ. In summary, Aβ can stimulate release of HspB1 from astrocytes, this release is insensitive to Golgi or lipid raft disruption, and HspB1 can be found either free in the medium or associated with exosomes. This release suggests that there is a potential for extracellular HspB1 to be able to bind and sequester extracellular Aβ.

DOI10.3233/JAD-150317
Alternate JournalJ. Alzheimers Dis.
PubMed ID26444769
Grant List / / Canadian Institutes of Health Research / Canada
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Source URL: https://www.j-alz.com/content/astrocytes-release-hspb1-response-amyloid-%CE%B2-exposure-vitro