Nox4 NADPH oxidase mediates peroxynitrite-dependent uncoupling of endothelial nitric-oxide synthase and fibronectin expression in response to angiotensin II: role of mitochondrial reactive oxygen species.
Activation of glomerular mesangial cells (MCs) by angiotensin II (Ang II) leads to extracellular matrix accumulation. Here, we demonstrate that, in MCs, Ang II induces endothelial nitric-oxide synthase (eNOS) uncoupling with enhanced generation of reactive oxygen species (ROS) and decreased production of NO. Ang II promotes a rapid increase in 3-nitrotyrosine formation, and uric acid attenuates Ang II-induced decrease in NO bioavailability, demonstrating that peroxynitrite mediates the effects of Ang II on eNOS dysfunction. Ang II rapidly up-regulates Nox4 protein. Inhibition of Nox4 abolishes the increase in ROS and peroxynitrite generation as well as eNOS uncoupling triggered by Ang II, indicating that Nox4 is upstream of eNOS. This pathway contributes to Ang II-mediated fibronectin accumulation in MCs. Ang II also elicits an increase in mitochondrial abundance of Nox4 protein, and the oxidase contributes to ROS production in mitochondria. Overexpression of mitochondrial manganese superoxide dismutase prevents the stimulatory effects of Ang II on mitochondrial ROS production, loss of NO availability, and MC fibronectin accumulation, whereas manganese superoxide dismutase depletion increases mitochondrial ROS, NO deficiency, and fibronectin synthesis basally and in cells exposed to Ang II. This work provides the first evidence that uncoupled eNOS is responsible for Ang II-induced MC fibronectin accumulation and identifies Nox4 and mitochondrial ROS as mediators of eNOS dysfunction. These data shed light on molecular processes underlying the oxidative signaling cascade engaged by Ang II and identify potential targets for intervention to prevent renal fibrosis.
From the Departments of Medicine and.
Doug-Yoon
DY
Lee
Fabien
F
Wauquier
Assaad A
AA
Eid
Linda J
LJ
Roman
Goutam
G
Ghosh-Choudhury
Khaled
K
Khazim
Karen
K
Block
Yves
Y
Gorin
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001682:Biological Availability; D005353:Fibronectins / Q000378:metabolism*; D005355:Fibrosis; D020868:Gene Silencing / Q000187:drug effects; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D050527:Mesangial Cells / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008954:Models, Biological; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D005353:Fibronectins; D017382:Reactive Oxygen Species; D013481:Superoxides; D000804:Angiotensin II; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498911:Nox4 protein, rat
Angiotensin II; Extracellular Matrix Proteins; Kidney; Nitric-oxide Synthase; Nox; Oxidative Stress