Laminar Shear Stress Up-regulates Peroxiredoxins (PRX) in Endothelial Cells

Abstract

Shear stress plays a significant role in endothelial cell biology and atherosclerosis development. Previous work by our group has shown that fluid flow stimulates important functional changes in cells through protein expression regulation. Peroxiredoxins (PRX) are a family of antioxidant enzymes but have yet to be investigated in response to shear stress. Studies have shown that oscillatory shear stress (OS) increases reactive oxygen species (ROS) levels in endothelial cells, whereas laminar shear stress (LS) blocks this response. We hypothesized that PRX are responsible for the anti-oxidative effect of LS. To test this hypothesis, bovine aortic endothelial cells (BAEC) were subjected to LS (15 dyn/cm 2 ), OS (؎5 dyn/cm 2 , 1 Hz), or static conditions for 24 h. Using Western blot and immunofluorescence staining, all six isoforms of PRX were identified in BAEC. When compared with OS and static, exposure to chronic LS up-regulated PRX 1 levels intracellularly. LS also increased expression of PRX 5 relative to static controls, but not OS. PRX exhibited broad subcellular localization, with distribution in the cytoplasm, Golgi, mitochondria, and intermediate filaments. In addition, PRX 1 knock down, using specific small interference RNA, attenuated LS-dependent reactive oxygen species reduction in BAEC. However, PRX 5 depletion did not. Together, these results suggest that PRX 1 is a novel mechanosensitive antioxidant, playing an important role in shear-dependent regulation of endothelial biology and atherosclerosis.Shear stress acting on the blood vessel wall plays an important role in the development of atherosclerosis. Straight regions of the arterial tree are considered "protected" from atherogenesis by high levels of unidirectional laminar shear stress (LS) 3 (1, 2). In contrast, plaque-prone areas in curves and bifurcations of the vasculature correspond to locales exposed to low or unstable shear stress, including oscillatory shear stress (OS) (2-4). These local mechanical forces have been correlated to the behavior of the exposed endothelium.Endothelial cells exposed to disturbed flow experience oxidative stress, inflammatory molecule expression, and monocyte recruitment as early signatures of atherosclerosis (5-9). In vitro studies have established that OS is a potent stimulator of reactive oxygen species (ROS) production in endothelial cells, and quantitative measurements by our group showed a significant increase in both OS-dependent superoxide (O 2 . ) and hydrogen peroxide (H 2 O 2 ) production (9 -12). We found that OS-stimulated ROS occurs in an NADPH oxidase-dependent manner and leads to inflammatory responses (ICAM-1) (intercellular adhesion molecule 1) expression and monocyte adhesion (10, 11). Conversely, LS acts to reduce ROS production and subsequent inflammatory response (10). Nevertheless, the mechanism by which LS restricts oxidative stress remains unclear. Antioxidant defense systems are critical to the protection of cellular macromolecules. They work to maintain a reductive cytosolic enviro...

Laminar shear stress inhibits lipid peroxidation induced by high glucose plus arachidonic acid in endothelial cells

“…This may be due to incomplete depletion of intracellular GSH or the presence of other defense mechanisms such as superoxide dismutase and peroxiredoxins (16,25). Although our data indicated that GSH plays a critical role in antioxidant defense by LSS, association of other antioxidants such as L-ascorbic acid and ␣-tocopherol cannot be excluded.…”

“…The regions of arteries experiencing laminar shear stress (LSS) due to orderly blood flow are usually protected from atherosclerotic lesion formation, and thus LSS of relatively high level has been proposed to play anti-atherogenic roles. Differently from oscillatory shear stress, LSS usually does not stimulate inflammatory reactions but suppresses them probably by increasing nitric oxide (NO) production rather than reactive oxygen species (ROS) (8) or by induction of enzymes associated with antioxidant defense (25).…”

The role of peroxidases in the pathogenesis of atherosclerosis

“…These isoforms regulate intracellular levels of H2O2 (91). Prdx1 is induced in macrophages by oxLDL exposure (92) and in endothelial cells by laminar shear stress (93). Prdx1 deficiency results in the excessive release of P-selectin and von Willebrand factor, proinflammatory components of Weibel-Palade bodies (94).…”

Vascular Mechanobiology Endothelial Cell Responses to Fluid Shear Stress

“…A recent study showed that laminar shear stress, but not oscillatory shear stress, increased expression of antioxidant enzyme peroxiredoxins by ECs. 50 …”