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.
| Zhou, Lulu; Zhang, Hongqiao; Davies, Kelvin J A et al. (2018) Aging-related decline in the induction of Nrf2-regulated antioxidant genes in human bronchial epithelial cells. Redox Biol 14:35-40 |
| Davies, Kelvin J A (2018) Cardiovascular Adaptive Homeostasis in Exercise. Front Physiol 9:369 |
| Pomatto, Laura C D; Sun, Patrick Y; Davies, Kelvin J A (2018) To adapt or not to adapt: Consequences of declining Adaptive Homeostasis and Proteostasis with age. Mech Ageing Dev : |
| Pomatto, Laura C D; Wong, Sarah; Tower, John et al. (2018) Sex-specific adaptive homeostasis in D. melanogaster depends on increased proteolysis by the 20S Proteasome: Data-in-Brief. Data Brief 17:653-661 |
| Fedoce, Alessandra das Graças; Ferreira, Frederico; Bota, Robert G et al. (2018) The role of oxidative stress in anxiety disorder: cause or consequence? Free Radic Res 52:737-750 |
| Pomatto, Laura C D; Davies, Kelvin J A (2018) Adaptive homeostasis and the free radical theory of ageing. Free Radic Biol Med 124:420-430 |
| Pomatto, Laura C D; Cline, Mayme; Woodward, Nicholas et al. (2018) Aging attenuates redox adaptive homeostasis and proteostasis in female mice exposed to traffic-derived nanoparticles ('vehicular smog'). Free Radic Biol Med 121:86-97 |
| Davies, Joanna M S; Cillard, Josiane; Friguet, Bertrand et al. (2017) The Oxygen Paradox, the French Paradox, and age-related diseases. Geroscience 39:499-550 |
| Cadet, Jean; Davies, Kelvin J A (2017) Oxidative DNA damage & repair: An introduction. Free Radic Biol Med 107:2-12 |
| Cadet, Jean; Davies, Kelvin J A (2017) Oxidative DNA damage & repair: An introduction. Free Radic Biol Med 106:100-110 |
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