Abstract 17951: S-glutathionylation of Rac1 is a Novel Mechanism of Vascular Barrier Dysfunction in Diabetes Mellitus
Background: — Protein S-glutathionylation (Pr-SSG) is a prevalent form of oxidative modification of reactive cysteines and serves as an important mode of redox signaling. Vascular redox dysregulation and impaired barrier function have long been recognized as early vascular alterations in diabetes, a major risk factor for atherosclerotic cardiovascular diseases, but the mechanistic link of Pr-SSG to the metabolic stress-induced endothelial cell (EC) hyper-permeability is not established and being investigated in the present study.
Methods and Results: — elevated Pr-SSG was observed in ECs isolated from patients with type-2 diabetes and atherosclerotic lesions of ApoE deficient (ApoE-/-) mice, concurring with a decrease in glutaredoxin-1 (Glrx-1), a specific deglutathionylation enzyme. Exposure of human aortic ECs to diabetic conditions increased the formation of Pr-SSG and permeability that was associated with the disassembly of cell adherens junctions and cortical actin structures, all of which were corrected by up-regulation of Glrx-1. We showed that small Rho GTPase Rac1, a redox sensitive signaling G protein essential for EC monolayer integrity, was glutathionylated and mediated the metabolic stress-induced hyper-permeability. Furthermore, in CRISPR-Cas9-mediated Rac1 knockout Cos-7 cells, site-directed mutagenesis of the cysteine residues and subsequent analysis of Rac1 mutants demonstrated that glutathionylation of Cys81 and Cys157 both contributed to the redox-dependent impairment of Rac1 activity status. Consistently, transgenic overexpression of Glrx-1 in ApoE-/- mice significantly attenuated high fat diet-induced Pr-SSG formation and actin cytoskeletal disorganization in aortic ECs, and subsequent vascular hyper-permeability and atherosclerotic lesion development.
Conclusions: — S-glutathionylation of Rac1 represents a novel redox mechanism of vascular barrier dysfunction associated with metabolic disorders, thus contributing to lipid and cellular infiltration and atherosclerotic progression.
Author Disclosures: R.M. Weisbrod: None. D. Shao: None. K.L. Kot: None. H. Edenbaum: None. R. Matsui: None. M. Bachschmid: None. N.M. Hamburg: None. R.A. Cohen: None. J. Han: None.
- © 2016 by American Heart Association, Inc.