title: The molecular chaperone Hsp70 promotes the proteolytic removal of oxidatively damaged proteins by the proteasome.
abstract: One hallmark of aging is the accumulation of protein aggregates, promoted by the unfolding of oxidized proteins. Unraveling the mechanism by which oxidized proteins are degraded may provide a basis to delay the early onset of features, such as protein aggregate formation, that contribute to the aging phenotype. In order to prevent aggregation of oxidized proteins, cells recur to the 20S proteasome, an efficient turnover proteolysis complex. It has previously been shown that upon oxidative stress the 26S proteasome, another form, dissociates into the 20S form. A critical player implicated in its dissociation is the Heat Shock Protein 70 (Hsp70), which promotes an increase in free 20S proteasome and, therefore, an increased capability to degrade oxidized proteins. The aim of this study was to test whether or not Hsp70 is involved in cooperating with the 20S proteasome for a selective degradation of oxidatively damaged proteins. Our results demonstrate that Hsp70 expression is induced in HT22 cells as a result of mild oxidative stress conditions. Furthermore, Hsp70 prevents the accumulation of oxidized proteins and directly promotes their degradation by the 20S proteasome. In contrast the expression of the Heat shock cognate protein 70 (Hsc70) was not changed in recovery after oxidative stress and Hsc70 has no influence on the removal of oxidatively damaged proteins. We were able to demonstrate in HT22 cells, in brain homogenates from 129/SV mice and in vitro, that there is an increased interaction of Hsp70 with oxidized proteins, but also with the 20S proteasome, indicating a role of Hsp70 in mediating the interaction of oxidized proteins with the 20S proteasome. Thus, our data clearly implicate an involvement of Hsp70 oxidatively damaged protein degradation by the 20S proteasome.
authors: German Institute of Human Nutrition Potsdam Rehbruecke (DIfE), Department of Molecular Toxicology, 14588 Nuthetal, Germany.
authors: Sandra
authors: S
authors: Reeg
authors: German Institute of Human Nutrition Potsdam Rehbruecke (DIfE), Department of Molecular Toxicology, 14588 Nuthetal, Germany; German Center for Diabetes Research (DZD), Germany.
authors: Tobias
authors: T
authors: Jung
authors: German Institute of Human Nutrition Potsdam Rehbruecke (DIfE), Department of Molecular Toxicology, 14588 Nuthetal, Germany; German Center for Diabetes Research (DZD), Germany.
authors: José P
authors: JP
authors: Castro
authors: University of Southern California, Leonard Davis School of Gerontology, and Division of Molecular & Computational Biology, Dornsife College of Letters, Arts, and Sciences, Los Angeles, CA 90089-0191, USA.
authors: Kelvin J A
authors: KJA
authors: Davies
authors: University Potsdam, Institute of Nutritional Science, Department of Physiology and Pathophysiology, 14588 Nuthetal, Germany.
authors: Andrea
authors: A
authors: Henze
authors: German Institute of Human Nutrition Potsdam Rehbruecke (DIfE), Department of Molecular Toxicology, 14588 Nuthetal, Germany; German Center for Diabetes Research (DZD), Germany. Electronic address: Scientific.director@dife.de.
authors: Tilman
authors: T
authors: Grune
mesh_terms: D000818:Animals; D002460:Cell Line; D002470:Cell Survival; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008297:Male; D051379:Mice; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D066329:Protein Aggregates; D059748:Proteolysis
chemical_list: D018840:HSP70 Heat-Shock Proteins; D009419:Nerve Tissue Proteins; D066329:Protein Aggregates; D049452:Green Fluorescent Proteins; D006861:Hydrogen Peroxide; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
keywords: Chaperone; HSP70; Proteasome; Protein oxidation