Stress-induced inhibition of the NF-kappaB signaling pathway results from the insolubilization of the IkappaB kinase complex following its dissociation from heat shock protein 90.
Activation of the stress response attenuates proinflammatory responses by suppressing cytokine-stimulated activation of the NF-kappaB signaling pathway. In this study, we show that the activation of the cellular stress response, either by heat shock treatment or after exposure to sodium arsenite, leads to a transient inhibition of IkappaBalpha phosphorylation. Inhibition of IkappaBalpha phosphorylation after stress was associated with the detergent insolubilization of the upstream kinases, IkappaB kinase alpha (IKKalpha) and IkappaB kinase beta, components involved in IkappaBalpha phosphorylation. Pretreatment of cells with glycerol, a chemical chaperone that reduces the extent of stress-induced protein denaturation, reduced the stress-dependent detergent insolubility of the IKK complex and restored the cytokine-stimulated phosphorylation of IkappaB. The stress-dependent insolubility of the IKK complex appeared reversible; as the cells recovered from the heat shock treatment, the IKK complex reappeared within the soluble fraction of cells and was again capable of mediating the phosphorylation of IkappaBalpha in response to added cytokines. Treatment of cells with geldanamycin, an inhibitor of heat shock protein 90 (Hsp90) function, also resulted in IKK detergent insolubility and proteasome-mediated degradation of the IKK complex. Furthermore, while IKKalpha coprecipitated with Hsp90 in control cells, coprecipitation of the two proteins was greatly reduced in those cells early after stress or following exposure to geldanamycin. Stress-induced transient insolubilization of the IkappaB kinase complex following its dissociation from Hsp90 represents a novel mechanism by which the activation of the stress response inhibits the NF-kappaB signaling pathway in response to proinflammatory stimuli.
Pittet
Jean-Francois
JF
Laboratory of Surgical Research, Department of Anesthesia, University of California-San Francisco, 1001 Potrero Avenue, San Francisco, CA 94110, USA. pittetj@anesthesia.ucsf.edu
Lee
Hyon
H
Pespeni
Melissa
M
O'Mahony
Allison
A
Roux
Jeremie
J
Welch
William J
WJ
D000818:Animals; D018053:Arsenites / Q000494:pharmacology; D016227:Benzoquinones; D015153:Blotting, Western; D002460:Cell Line; D003451:Cryoprotective Agents / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D005990:Glycerol / Q000494:pharmacology; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D051550:I-kappa B Kinase; D047468:Immunoprecipitation; D047029:Lactams, Macrocyclic; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D051381:Rats; D017670:Sodium Compounds / Q000494:pharmacology; D012995:Solubility; D013312:Stress, Physiological / Q000503:physiopathology*
D018053:Arsenites; D016227:Benzoquinones; D003451:Cryoprotective Agents; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D016328:NF-kappa B; D011809:Quinones; D017670:Sodium Compounds; C017947:sodium arsenite; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D005990:Glycerol; C001277:geldanamycin