on April 12, 2007
Published online before print April 12, 2007, doi: 10.1161/ATVBAHA.107.144659
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Submitted on January 31, 2006
Accepted on March 28, 2007
Glutaredoxin Mediates Akt and eNOS Activation by Flow in a Glutathione Reductase-Dependent Manner
Jing Wang ;
From the Cardiovascular Research Institute and Department of Medicine, University of Rochester, NY.
* To whom correspondence should be addressed. E-mail: Shi_Pan{at}urmc.rochester.edu.
Objective--The glutathione (GSH)/glutaredoxin (Grx) system regulates activities of many redox sensitive enzymes. This system has been shown to protect cells from hydrogen peroxide-induced apoptosis by regulating the redox state of Akt. Grx can be regulated by redox state; the oxidized Grx is selectively recycled to the reduced form by GSH. Flow can maintain endothelial cells in a reduced state by activating glutathione reductase (GR) and increasing the GSH/GSSG ratio. Because steady laminar flow exerts an antioxidant effect, we hypothesized that Grx mediates flow induced Akt and eNOS phosphorylation in a GR dependent manner.
Methods and Results--Exposure of endothelial cells (ECs) to physiological steady laminar flow (shear stress=12 dyn/cm2) for 5 minutes significantly increased Grx activity (1.9±0.2-fold), and also increased Akt and eNOS phosphorylation. Overexpression of GFP-GR in ECs significantly increased Grx activity by 1.6±0.1-fold. Pretreatment with the GR inhibitor 1,3-bis[2-chloroethyl]-1-nitrosourea (BCNU) for 30 minutes dramatically reduced Grx activity and inhibited the increase in Akt and eNOS phosphorylation induced by flow. Overexpression of wild-type Grx in ECs increased both Akt and eNOS phosphorylation. In contrast, a mutated Grx (C22S/C25S), which lacks thioltransferase activity, had no effect. Therefore, flow-induced Akt and eNOS phosphorylation depend on Grx thioltransferase activity. Downregulation of Grx by small interfering RNA decreased flow induced Akt and eNOS phosphorylation.
Conclusions--These data suggest that Grx is an important mediator for flow-induced Akt and eNOS activation, and Grx activity depends on GR-mediated changes in EC redox state.
Key words: Grx • Akt • eNOS • GR • endothelial cells
This article has been cited by other articles:
 |
|
 |
|
  E. H. Heiss, D. Schachner, E. R. Werner, and V. M. Dirsch Active NF-E2-related Factor (Nrf2) Contributes to Keep Endothelial NO Synthase (eNOS) in the Coupled State: ROLE OF REACTIVE OXYGEN SPECIES (ROS), eNOS, AND HEME OXYGENASE (HO-1) LEVELS J. Biol. Chem., November 13, 2009; 284(46): 31579 - 31586. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.-L. Balligand, O. Feron, and C. Dessy eNOS Activation by Physical Forces: From Short-Term Regulation of Contraction to Chronic Remodeling of Cardiovascular Tissues Physiol Rev, April 1, 2009; 89(2): 481 - 534. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Seefeldt, Y. Zhao, W. Chen, A. S. Raza, L. Carlson, J. Herman, A. Stoebner, S. Hanson, R. Foll, and X. Guan Characterization of a Novel Dithiocarbamate Glutathione Reductase Inhibitor and Its Use as a Tool to Modulate Intracellular Glutathione J. Biol. Chem., January 30, 2009; 284(5): 2729 - 2737. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. C. Berk Atheroprotective Signaling Mechanisms Activated by Steady Laminar Flow in Endothelial Cells Circulation, February 26, 2008; 117(8): 1082 - 1089. [Full Text] [PDF]
|
|