Fluid shear stress attenuates hydrogen peroxide-induced c-Jun NH2-terminal kinase activation via a glutathione reductase-mediated mechanism.
ABSTRACT c-Jun NH2-terminal kinase (JNK) is activated by a number of cellular stimuli including reactive oxygen species (ROS). Previous studies have demonstrated that fluid shear stress (flow) inhibits cytokine-induced JNK activation in endothelial cells (ECs). In the present study, we show JNK activation by ROS in ECs and hypothesized that flow inhibits ROS-induced JNK activation in ECs via modulation of cellular protection systems against ROS. JNK was activated by 300 micro mol/L hydrogen peroxide (H2O2) in bovine lung microvascular ECs (BLMVECs) with a peak at 60 minutes after stimulation (6.3+/-1.2-fold increase). Preexposure of BLMVECs to physiological steady laminar flow (shear stress=12 dyne/cm2) for 10 minutes significantly decreased H2O2-induced JNK activation. Thioredoxin and glutathione are cellular antioxidants that protect cells against ROS. Flow induced a significant increase in the ratio of reduced glutathione to oxidized glutathione consistent with a 1.6-fold increase in glutathione reductase (GR) activity. Preincubation of BLMVECs with the GR inhibitor, 1,3 bis-(2 chloroethyl)-1-nitrosourea, abolished the inhibitory effect of flow. In contrast, preincubation of BLMVECs with azelaic acid, a specific inhibitor for thioredoxin reductase, did not alter the effect of flow on H2O2-induced JNK activation. Overexpression of GR mimicked the effect of flow to inhibit JNK activation. These results suggest that flow activates GR, an important regulator of the intracellular redox state of glutathione, and exerts a protective mechanism against oxidative stress in endothelial cells.
- SourceAvailable from: Predrag Vlahovic
Chapter: Endothelial Cells and VasculitisAdvances in the Etiology, Pathogenesis and Pathology of Vasculitis, 10/2011; , ISBN: 978-953-307-651-5
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ABSTRACT: During the past decade nutrigenomic studies in humans, animal models and cultured cells have provided important and novel insights into the mechanisms by which dietary isoflavones afford protection against vascular dysfunction through the amelioration of oxidative modifications and upregulation of endogenous antioxidant signaling pathways. In this review, we highlight that increased generation of nitric oxide (NO) and reactive oxygen species (ROS) in the vessel wall in response to dietary isoflavones enhance the activity of antioxidant defense enzymes in endothelial and smooth muscle cells. The estrogenic properties of isoflavones are likely to contribute to the molecular mechanisms by which these compounds activate signal transduction pathways involved in sustaining endothelial function and transcriptional activation of antioxidant defense genes in vascular cells. We evaluate the recent literature that estrogenic and hormetic properties of phytoestrogens are of benefit for the maintenance of vascular function, and conclude that dietary isoflavones can protect against cardiovascular diseases by virtue of their ability to activate signaling pathways leading to increased NO bioavailability and regulation of phase II and antioxidant enzyme expression via the redox sensitive transcription factor Nrf2. In context of epigenetics and the developmental origins of adult disease, it is noteworthy that exposure to dietary soy during fetal development reduces the susceptibility to CVD and obesity in adulthood. Thus, the Nrf2/Keap1 defense pathway provides a key mechanism by which isoflavones can act as hormetic agents to modulate intracellular redox signaling in the vasculature to prolong healthspan and reduce the incidence of age-related cardiovascular diseases.Molecular Aspects of Medicine 12/2010; 31(6):468-77. DOI:10.1016/j.mam.2010.09.003 · 10.30 Impact Factor
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ABSTRACT: Atherosclerosis is a chronic disease that involves inflammation, in which cytokines, including interferon-gamma (IFNgamma), participate. Endothelial cells (ECs) exposed to IFNgamma increase the expression of CXC chemokines. ECs subjected to laminar flow (LF) are atheroprotective, despite an unclear mechanism. This study was conducted to analyze whether ECs under LF were protected from IFNgamma-induced responses. IFNgamma-treated human umbilical cord ECs were subjected to LF in a well-defined flow chamber system. IFNgamma-induced STAT1 activation and downstream target genes were examined. ECs exposed to IFNgamma triggered STAT1 activation via the phosphorylation of Tyr701 and Ser727 in STAT1. ECs exposed to LF alone did not activate STAT1. LF exposure of IFNgamma-treated ECs significantly attenuated IFNgamma-induced Tyr701 phosphorylation in a shear-force- and time-dependent manner, whereas Ser727 phosphorylation was unaffected. Consistently, LF inhibited IFNgamma-induced STAT1 binding to DNA. ECs treated with IFNgamma induced the expression of three T-cell-specific CXC chemokines (CXCL9, CXCL10 and CXCL11) as well as CIITA, a transcriptional regulator of major histocompatibility complex class II (MHCII). Consistently, LF exposure of IFNgamma-treated ECs reduced the expression of CXC chemokines and CIITA. LF attenuates IFNgamma-induced responses via the suppression of STAT1 activation. Inhibition by LF of the interferon-induced ECs' response may explain some aspects of LF's atheroprotective effects on the endothelium.Cardiovascular Research 07/2007; 74(3):497-505. DOI:10.1016/j.cardiores.2007.02.030 · 5.81 Impact Factor