Proteins are major targets of oxidative modification by many environmental toxicants. They lose function &structure, and must be proteolyticaly degraded or they will aggregate and form cross- linked cellular inclusion bodies. We have shown a major role for the Proteasome in detoxifying oxidized proteins. Now we find proteasome is under dynamic control, exchanging regulators and catalytic subunits, and exhibiting de novo synthesis in adaptation to mild, acute stress. Our Long-term Goals are to understand the mechanisms by which Proteasome contributes to basal and inducible oxidative stress resistance, the contributions of this detoxification system to human health, and how aging can compromise such resistance.
Our Specific Aims are to test the following hypotheses: 1) Exposure of human HBE1 cells or primary human NHBE cells to hydrogen peroxide (H2O2), causes transient and reversible disassembly of 26S Proteasomes catalyzed by Ecm29, with stabilization of 19S regulators by HSP70. Dissociation of 26S Proteasomes prevents Nrf2 degradation, leading to Nrf2 accumulation, phosphorylation, and nuclear translocation;2) Exposure of HBE1 human cells or primary human NHBE cells to a mild adaptive dose of H2O2, causes Nrf2 to bind to ARE (or EpRE) sequences of 20S Proteasome subunit genes and Pa28??? genes, and up-regulate their expression within 5-10 hours after H2O2 exposure. The Irf-1 and/or NF?B transcription factors simultaneously bind to upstream regions of the three Immunoproteasome genes, and up-regulate Immunoproteasome and Pa28?? expression;3) Adaptation of C. elegans and D. melanogaster to H2O2 requires 20S Proteasome and Pa28? expression, via the skn-1 and cnc-C homologs of Nrf2;4)The capacity to adapt to oxidative stress declines in senescent HBE1 and primary NHBE cells, in our model of hyperoxia-accelerated aging of non-dividing HBE1 and NHBE cells, and in NHBE cells from older human donors, partly due to diminished Nrf2 and Irf-1/NF?B signaling of Proteasome, Pa2???, and Immunoproteasome synthesis. H2O2-induced expression of Pa28? and Proteasome, through Nrf2 homologs skn-1 and cnc-C, also decays during aging of C. elegans and D. melanogaster, contributing to age-related decline in overall stress resistance and adaptability.
Oxidative damage to proteins is a well-characterized outcome of exposure to a wide variety of environmental toxicants. So serious is the problem of environmental oxidants that the NIEHS made discovering the mechanisms of oxidative stress a major focus in its 2006-2011 Strategic Plan, entitled New Frontiers in Environmental Sciences and Human Health. We seek to identify the mechanisms by which the proteasome enzyme protects against environmental oxidative stress, and allows us to adapt to increased stress levels.
|Forman, Henry J; Davies, Kelvin J A; Ursini, Fulvio (2014) How do nutritional antioxidants really work: nucleophilic tone and para-hormesis versus free radical scavenging in vivo. Free Radic Biol Med 66:24-35|
|Pickering, Andrew M; Vojtovich, Lesya; Tower, John et al. (2013) Oxidative stress adaptation with acute, chronic, and repeated stress. Free Radic Biol Med 55:109-18|
|Pickering, Andrew M; Staab, Trisha A; Tower, John et al. (2013) A conserved role for the 20S proteasome and Nrf2 transcription factor in oxidative stress adaptation in mammals, Caenorhabditis elegans and Drosophila melanogaster. J Exp Biol 216:543-53|
|Ngo, Jenny K; Pomatto, Laura C D; Davies, Kelvin J A (2013) Upregulation of the mitochondrial Lon Protease allows adaptation to acute oxidative stress but dysregulation is associated with chronic stress, disease, and aging. Redox Biol 1:258-64|
|Ermak, Gennady; Sojitra, Sonal; Yin, Fei et al. (2012) Chronic expression of RCAN1-1L protein induces mitochondrial autophagy and metabolic shift from oxidative phosphorylation to glycolysis in neuronal cells. J Biol Chem 287:14088-98|
|Pickering, Andrew M; Linder, Robert A; Zhang, Hongqiao et al. (2012) Nrf2-dependent induction of proteasome and Pa28?? regulator are required for adaptation to oxidative stress. J Biol Chem 287:10021-31|
|Pickering, Andrew M; Davies, Kelvin J A (2012) A simple fluorescence labeling method for studies of protein oxidation, protein modification, and proteolysis. Free Radic Biol Med 52:239-46|
|Ngo, Jenny K; Pomatto, Laura C D; Bota, Daniela A et al. (2011) Impairment of lon-induced protection against the accumulation of oxidized proteins in senescent wi-38 fibroblasts. J Gerontol A Biol Sci Med Sci 66:1178-85|
|Lloret, Ana; Badia, Mari-Carmen; Giraldo, Esther et al. (2011) Amyloid-? toxicity and tau hyperphosphorylation are linked via RCAN1 in Alzheimer's disease. J Alzheimers Dis 27:701-9|
|Grune, Tilman; Catalgol, Betul; Licht, Anke et al. (2011) HSP70 mediates dissociation and reassociation of the 26S proteasome during adaptation to oxidative stress. Free Radic Biol Med 51:1355-64|
Showing the most recent 10 out of 11 publications