Circadian modulation of proteasome activity and accumulation of oxidized protein in human embryonic kidney HEK 293 cells and primary dermal fibroblasts.

The circadian system orchestrates the timing of physiological processes of an organism living in daily environmental changes. Disruption of circadian rhythmicity has been shown to result in increased oxidative stress and accelerated aging. The circadian regulation of antioxidant defenses suggests that other redox homeostasis elements such as oxidized protein degradation by the proteasome, could also be modulated by the circadian clock.

Skin protection against dicarbonyl stress by the glyoxalase system.

Skin ageing is the result of intrinsic and photo-ageing, due to UV exposure, that both share important molecular features including alterations of proteins. Indeed, proteins can be modified by many molecular processes such as glycation. Glycation occurs when glucose or its derivates the dicarbonyl compounds glyoxal (GO) and methylglyoxal (MG) react with amines of proteins leading to the formation of advanced glycation endproducts (AGE).

Prevention of dicarbonyl-mediated advanced glycation by glyoxalases: implication in skin aging.

Skin aging is the result of intrinsic chronological aging and photoaging, due to UV exposure, that both share important histological modifications and molecular features, including alterations of proteins. One of the main damage is glycation that occurs when reducing sugars react non-enzymatically with proteins. This reaction also happens when the dicarbonyl compounds GO (glyoxal) and MG (methylglyoxal), which are glucose derivatives, react with proteins.

Proteome alteration in oxidative stress-sensitive methionine sulfoxide reductase-silenced HEK293 cells.

Methionine sulfoxide reductases (Msr's) are key enzymes proficient in catalyzing the reduction of oxidized methionines. This reductive trait is essential to maintaining cellular redox homeostasis from bacteria to mammals and is also regarded as a potential mechanism to regulate protein activities and signaling pathways, considering the inactivating effects that can be induced by methionine oxidation. In this study, we have generated stable human embryonic kidney HEK293 clones with an altered Msr system by silencing the expression of the main Msr elements-MsrA, MsrB1, or MsrB2.