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The Production of ExtraCellular Vesicles Is Increased after Heat Shock
Author(s) -
De Maio Antonio,
Hawisher Dennis,
Lara Bernardo,
Cauvi David M.
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.810.2
Subject(s) - microbiology and biotechnology , heat shock protein , extracellular , hsp70 , cytosol , homeostasis , heat shock , microvesicles , intracellular , biology , chemistry , vesicle , biochemistry , microrna , enzyme , membrane , gene
When organisms are exposed to extreme conditions or stresses homeostasis is compromised. The natural cellular response to changes in homeostasis is mediated by the expression of a family of proteins coined heat shock proteins (hsp). These proteins are involved in the stabilization of basic cellular processes to preserve cell viability and to guaranty the return to homeostasis. In addition, they protect cells from subsequent insults in a time‐dependent fashion. The bulk of hsp function occurred within the cytosol and subcellular compartments. However, hsp have also been found outside cells acting as signaling molecules directed at activating a systemic response to stress. Extracellular hsp are released after cell death by necrosis in a soluble form. Hsp are also exported by an active mechanism independent of cell death, in which hsp are associated with extracellular vesicles (ECV). Indeed, hsp have been detected in numerous preparations of ECV from different sources. We investigated the release of ECV after heat shock (HS) in human hepatoblastoma cells (HepG2). We observed a rapid production of ECV within a few hours after the insult. There were no differences in the size of vesicles derived from HS and control cells. However, HS cells produced between 2–3 folds more ECV than non‐stressed cells. Analysis of the biochemical composition of ECV after HS revealed the presence of Hsp70, the major inducible form of hsp. Stress ECV were highly enriched in other cellular components, including tubulin and actin, in comparison with vesicles derived from stressed cells. These observations suggest that the mechanism of ECV release is different between stress and normal conditions. Finally, we propose that stress ECV induce a systemic response directed at avoiding the propagation of the insult, which has been named the “stress observation system” (SOS).