Oxidative Stress Promotes Peroxiredoxin Hyperoxidation and Attenuates Pro-survival Signaling in Aging Chondrocytes

Abstract

Oxidative stress-mediated post-translational modifications of redox-sensitive proteins are postulated as a key mechanism underlying age-related cellular dysfunction and disease progression. Peroxiredoxins (PRX) are critical intracellular antioxidants that also regulate redox signaling events. Age-related osteoarthritis is a common form of arthritis that has been associated with mitochondrial dysfunction and oxidative stress. The objective of this study was to determine the effect of aging and oxidative stress on chondrocyte intracellular signaling, with a specific focus on oxidation of cytosolic PRX2 and mitochondrial PRX3. Menadione was used as a model to induce cellular oxidative stress. Compared with chondrocytes isolated from young adult humans, chondrocytes from older adults exhibited higher levels of PRX1-3 hyperoxidation basally and under conditions of oxidative stress. Peroxiredoxin hyperoxidation was associated with inhibition of pro-survival Akt signaling and stimulation of pro-death p38 signaling. These changes were prevented in cultured human chondrocytes by adenoviral expression of catalase targeted to the mitochondria (MCAT) and in cartilage explants from MCAT transgenic mice. Peroxiredoxin hyperoxidation was observed in situ in human cartilage sections from older adults and in osteoarthritic cartilage. MCAT transgenic mice exhibited less age-related osteoarthritis. These findings demonstrate that age-related oxidative stress can disrupt normal physiological signaling and contribute to osteoarthritis and suggest peroxiredoxin hyperoxidation as a potential mechanism.Aging is characterized by an inability to maintain homeostasis resulting in a progressive loss of function and is associated with many chronic conditions including cancer, type II diabetes, neurodegenerative disease, cardiovascular disease, and osteoarthritis (1, 2). Although several theories aimed at explaining the aging phenotype have been suggested, an age-related imbalance between the production of reactive oxygen species (ROS) 2 and the antioxidant capacity of the cell has been identified as a contributing factor (3-5). Although the original free radical theory of aging focused on accumulation of cellular damage from excessive ROS as a cause for aging and age-related conditions, more recent studies suggest that disturbances in redox signaling that result from age-related oxidative stress are likely to play a key role (5-7). Increased levels of ROS caused by mitochondrial dysfunction, one of the hallmarks of aging, have been proposed to contribute to age-related oxidative stress, but the underlying mechanisms for how this increase causes a disruption in cell signaling leading to cell and tissue dysfunction is poorly understood (1, 4, 8).Recent advances in redox signaling recognize that reversible post-translational oxidative modifications of reactive protein cysteine thiols mediated by controlled production of H 2 O 2 regulate key signal transduction events (9, 10). The cysteine-dependent peroxiredoxins (PRXs), which display high rea...

Ageing and the pathogenesis of osteoarthritis

“…Hyperoxidation of the peroxiredoxin family of antioxidant enzymes has been demonstrated in cartilage samples from older adult humans and patients with OA 81 . Conditions of oxidative stress (induced in vitro with the ROS generator menadione) led to an age-related increase in peroxiredoxin hyperoxidation, which was associated with both inhibition of pro-survival cell signalling and p38 MAPK-induced chondrocyte cell death 81 .…”

“…Hyperoxidation of the peroxiredoxin family of antioxidant enzymes has been demonstrated in cartilage samples from older adult humans and patients with OA 81 . Conditions of oxidative stress (induced in vitro with the ROS generator menadione) led to an age-related increase in peroxiredoxin hyperoxidation, which was associated with both inhibition of pro-survival cell signalling and p38 MAPK-induced chondrocyte cell death 81 . Importantly, reduction of ROS levels by mitochondrion-specific overexpression of the antioxidant enzyme catalase prevented peroxiredoxin hyperoxidation in vitro , and reduced the severity of age-related OA in mice in vivo 81 .…”

“…Conditions of oxidative stress (induced in vitro with the ROS generator menadione) led to an age-related increase in peroxiredoxin hyperoxidation, which was associated with both inhibition of pro-survival cell signalling and p38 MAPK-induced chondrocyte cell death 81 . Importantly, reduction of ROS levels by mitochondrion-specific overexpression of the antioxidant enzyme catalase prevented peroxiredoxin hyperoxidation in vitro , and reduced the severity of age-related OA in mice in vivo 81 . Collectively, these studies highlight ROS as crucial secondary signalling molecules in chondrocytes that warrant further study in the context of ageing and OA.…”

Effect of biomechanical stress on endogenous antioxidant networks in bovine articular cartilage

“…Furthermore, we did not quantify changes in the rate or source of ROS production under the different loading conditions. This information could help to identify which antioxidants are most proximal to the source of ROS production, such as the antioxidants SOD2 and PRDX3 for mitochondrial ROS . New methods to assess organelle‐specific measures of ROS production and oxidative stress in vivo are becoming more widely available and offer new opportunities for future investigations .…”

“…This information could help to identify which antioxidants are most proximal to the source of ROS production, such as the antioxidants SOD2 and PRDX3 for mitochondrial ROS. 10,38,39 New methods to assess organelle-specific measures of ROS production and oxidative stress in vivo are becoming more widely available and offer new opportunities for future investigations. 40,41 Finally, additional evidence is needed to define the mechanism by which cyclic loading upregulates GSH synthesis in a stress-dependent manner.…”