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Induction of heat shock proteins and their possible roles in macrophages during activation by macrophage
S Teshima1, K Rokutan, M Takahashi
1Department of Nutrition, School of Medicine, University of Tokushima, Japan.
Abstract:
(1) Treatment of resident peritoneal macrophages for 8 h with macrophage colony-stimulating factor (M-CSF) increased release of superoxide anion (O2-) stimulated by phorbol 12-myristate 13-acetate. Gel electrophoresis of pulse-labelled proteins with L-[35S]methionine showed that a number of proteins were induced during activation by M-CSF. Immunoblot analysis with antibody against heat shock protein (HSP) 90, HSP70, or HSP60 demonstrated that M-CSF induced these stress-inducible HSPs; the timing of induction and level of each HSP correlated with the increase in O2- production. The activated macrophages acquired resistance to H2O2-induced damage. M-CSF also stimulated the synthesis of a heat shock cognate protein (HSC70); however, the induction occurred at 1 h, when O2- production was not yet augmented, but at which time L-[35S]methionine incorporation into cell proteins was already enhanced. (2) Gel mobility shift assay with oligonucleotide coding for the heat shock element showed that M-CSF activated the heat shock factor within 15 min, and the activation continued for at least 8 h. Northern-blot analysis with a cDNA probe for human HSP70 or HSC70 showed that accumulations of HSP70 and HSC70 mRNAs coincided with the inductions of the respective proteins. (3) These results suggest that M-CSF may induce the transcriptional activation of heat shock genes, and that the stress-inducible HSPs as well as HSC70 may play an important role in the activation of macrophages by functioning as molecular chaperones and by protecting the macrophage against the auto-oxidative damage associated with the respiratory burst.
Insights
Macrophage colony-stimulating factor (M-CSF) activates macrophages, increasing superoxide production and heat shock protein (HSP) synthesis. These HSPs protect macrophages from oxidative damage, suggesting a key role in macrophage activation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Resident peritoneal macrophages are crucial immune cells.
- Macrophage activation involves complex molecular signaling pathways.
- Heat shock proteins (HSPs) are involved in cellular stress responses.
Purpose of the Study:
- To investigate the role of macrophage colony-stimulating factor (M-CSF) in macrophage activation.
- To determine the involvement of heat shock proteins (HSPs) in M-CSF-induced macrophage activation.
- To elucidate the protective mechanisms of HSPs in activated macrophages.
Main Methods:
- Treatment of macrophages with M-CSF.
- Measurement of superoxide anion (O2-) release.
- Analysis of protein synthesis using gel electrophoresis and immunoblotting.
- Assessment of heat shock factor activation using gel mobility shift assay.
- mRNA analysis using Northern-blotting.
Main Results:
- M-CSF treatment increased O2- production and induced synthesis of HSP90, HSP70, and HSP60.
- Activated macrophages showed increased resistance to H2O2-induced damage.
- M-CSF stimulated heat shock factor activation within 15 minutes.
- Accumulation of HSP70 and HSC70 mRNAs correlated with protein induction.
- M-CSF also stimulated the synthesis of heat shock cognate protein (HSC70).
Conclusions:
- M-CSF induces transcriptional activation of heat shock genes in macrophages.
- Stress-inducible HSPs and HSC70 play a significant role in macrophage activation.
- HSPs function as molecular chaperones and protect macrophages from oxidative damage during respiratory burst.