title: Geldanamycin restores a defective heat shock response in vivo.
abstract: Induced expression of heat shock proteins (Hsps) plays a central role in promoting cellular survival after environmental and physiological stress. We have previously shown that scrapie-infected mouse neuroblastoma (ScN2a) cells fail to induce the expression of Hsp72 and Hsp28 after various stress conditions. Here we present evidence that this impaired stress response is due to an altered regulation of HSF1 activity. Upon stress in ScN2a cells, HSF1 was converted into hyperphosphorylated trimers but failed to acquire transactivation competence. A kinetic analysis of HSF1 activation revealed that in ScN2a cells trimer formation after stress was efficient, but disassembly of trimers proceeded much faster than in the uninfected cell line. Geldanamycin, a Hsp90-binding drug, significantly delayed disassembly of HSF1 trimers after a heat shock and restored stress-induced expression of Hsp72 in ScN2a cells. Heat-induced Hsp72 expression required geldanamycin to be present; following removal of the drug ScN2a cells again lost their ability to mount a stress response. Thus, our studies show that a defective stress response can be pharmacologically restored and suggest that the HSF1 deactivation pathway may play an important role in the regulation of Hsp expression.
authors.affiliation: Department of Cellular Biochemistry, Max-Planck-Institut für Biochemie and the Max-Planck-Institut für Neurobiologie, D-82152 Martinsried, Germany.
authors.forename: K F
authors.initials: KF
authors.lastname: Winklhofer
authors.forename: A
authors.initials: A
authors.lastname: Reintjes
authors.forename: M C
authors.initials: MC
authors.lastname: Hoener
authors.forename: R
authors.initials: R
authors.lastname: Voellmy
authors.forename: J
authors.initials: J
authors.lastname: Tatzelt
mesh_terms: D000818:Animals; D016227:Benzoquinones; D015153:Blotting, Western; D002455:Cell Division / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D003902:Detergents / Q000494:pharmacology; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation; D050884:HSP72 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D006358:Hot Temperature; D007700:Kinetics; D047029:Lactams, Macrocyclic; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011809:Quinones / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism; D012608:Scrapie / Q000378:metabolism; D013312:Stress, Physiological; D013696:Temperature; D013997:Time Factors; D014157:Transcription Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D016227:Benzoquinones; D004268:DNA-Binding Proteins; D003902:Detergents; D004791:Enzyme Inhibitors; D050884:HSP72 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D011809:Quinones; D011994:Recombinant Proteins; D014157:Transcription Factors; D008156:Luciferases; D001616:beta-Galactosidase; C001277:geldanamycin