title: HSP70 mediates dissociation and reassociation of the 26S proteasome during adaptation to oxidative stress.
abstract: We report an entirely new role for the HSP70 chaperone in dissociating 26S proteasome complexes (into free 20S proteasomes and bound 19S regulators), preserving 19S regulators, and reconstituting 26S proteasomes in the first 1-3h after mild oxidative stress. These responses, coupled with direct 20S proteasome activation by poly(ADP ribose) polymerase in the nucleus and by PA28αβ in the cytoplasm, instantly provide cells with increased capacity to degrade oxidatively damaged proteins and to survive the initial effects of stress exposure. Subsequent adaptive (hormetic) processes (3-24h after stress exposure), mediated by several signal transduction pathways and involving increased transcription/translation of 20S proteasomes, immunoproteasomes, and PA28αβ, abrogate the need for 26S proteasome dissociation. During this adaptive period, HSP70 releases its bound 19S regulators, 26S proteasomes are reconstituted, and ATP-stimulated proteolysis is restored. The 26S proteasome-dependent, and ATP-stimulated, turnover of ubiquitinylated proteins is essential for normal cell metabolism, and its restoration is required for successful stress adaptation.
authors.affiliation: Institute of Nutrition, Department of Nutritional Toxicology, Friedrich Schiller University, Jena, Germany. tilman.grune@uni-jena.de
authors.forename: Tilman
authors.initials: T
authors.lastname: Grune
authors.forename: Betül
authors.initials: B
authors.lastname: Catalgol
authors.forename: Anke
authors.initials: A
authors.lastname: Licht
authors.forename: Gennady
authors.initials: G
authors.lastname: Ermak
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Pickering
authors.forename: Jenny K
authors.initials: JK
authors.lastname: Ngo
authors.forename: Kelvin J A
authors.initials: KJ
authors.lastname: Davies
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D020014:K562 Cells; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics*; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000502:physiology; D059748:Proteolysis; D015398:Signal Transduction; D014158:Transcription, Genetic; D054875:Ubiquitination
chemical_list: D018840:HSP70 Heat-Shock Proteins; D009124:Muscle Proteins; C085047:PSME1 protein, human; D011065:Poly(ADP-ribose) Polymerases; C486207:PSME2 protein, human; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; C119011:26S proteasome non-ATPase regulatory subunit 13