Activation of heat shock factor 1 plays a role in pyrrolidine dithiocarbamate-mediated expression of the co-chaperone BAG3.

Abstract

Adaptive responses to physical and inflammatory stressors are mediated by transcription factors and molecular chaperones. The transcription factor heat shock factor 1 (HSF1) has been implicated in extending lifespan in part by increasing expression of heat shock response genes. Pyrrolidine dithiocarbamate (PDTC) is a small thiol compound that exerts in vivo and in vitro anti-inflammatory properties through mechanisms that remain unclear. Here we report that PDTC induced the release of monomeric HSF1 from the molecular chaperone heat shock protein 90 (Hsp90), with concomitant increase in HSF1 trimer formation, translocation to the nucleus, and binding to promoter of target genes in human HepG2 cells. siRNA-mediated silencing of HSF1 blocked BAG3 gene expression by PDTC. The protein levels of the co-chaperone BAG3 and its interaction partner Hsp72 were stimulated by PDTC in a dose-dependent fashion, peaking at 6h. Inhibition of Hsp90 function by geldanamycin derivatives and novobiocin elicited a pattern of HSF1 activation and BAG3 expression that was similar to PDTC. Chromatin immunoprecipitation studies showed that PDTC and the inhibitor 17-dimethylaminoethylamino-17-demethoxygeldanamycin enhanced the binding of HSF1 to the promoter of several target genes, including BAG3, HSPA1A, HSPA1B, FKBP4, STIP1 and UBB. Cell treatment with PDTC increased significantly the level of Hsp90α thiol oxidation, a posttranslational modification known to inhibit its chaperone function. These results unravel a previously unrecognized mechanism by which PDTC and related compounds could confer cellular protection against inflammation through HSF1-induced expression of heat shock response genes.

• Authors: Shaoming Song, Sutapa Kole, Patricia Precht, Michael J Pazin, Michel Bernier
• Journal: The international journal of biochemistry & cell biology (Int J Biochem Cell Biol) Vol. 42 Issue 11 Pg. 1856-63 (Nov 2010) ISSN: 1878-5875 [Electronic] Netherlands
• PMID: 20692357 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)
• Copyright: Published by Elsevier Ltd.

Chemical References

• Adaptor Proteins, Signal Transducing
• Apoptosis Regulatory Proteins
• BAG3 protein, human
• Benzoquinones
• DNA-Binding Proteins
• HSF1 protein, human
• HSP72 Heat-Shock Proteins
• HSP90 Heat-Shock Proteins
• Heat Shock Transcription Factors
• Lactams, Macrocyclic
• Pyrrolidines
• Thiocarbamates
• Transcription Factors
• Novobiocin
• pyrrolidine dithiocarbamic acid
• geldanamycin

Topics

• Adaptor Proteins, Signal Transducing (genetics, metabolism)
• Apoptosis Regulatory Proteins
• Benzoquinones (pharmacology)
• Blotting, Western
• Chromatin Immunoprecipitation
• DNA-Binding Proteins (genetics, metabolism)
• HSP72 Heat-Shock Proteins
• HSP90 Heat-Shock Proteins (metabolism)
• Heat Shock Transcription Factors
• Hep G2 Cells
• Humans
• Lactams, Macrocyclic (pharmacology)
• Novobiocin (pharmacology)
• Polymerase Chain Reaction
• Protein Binding (drug effects)
• Pyrrolidines (pharmacology)
• RNA Interference
• Thiocarbamates (pharmacology)
• Transcription Factors (genetics, metabolism)
• Tumor Cells, Cultured