NADPH oxidase signal transduces angiotensin II in hepatic stellate cells and is critical in hepatic fibrosis.
Angiotensin II (Ang II) is a pro-oxidant and fibrogenic cytokine. We investigated the role of NADPH oxidase in Ang II-induced effects in hepatic stellate cells (HSCs), a fibrogenic cell type. Human HSCs express mRNAs of key components of nonphagocytic NADPH oxidase. Ang II phosphorylated p47phox, a regulatory subunit of NADPH oxidase, and induced reactive oxygen species formation via NADPH oxidase activity. Ang II phosphorylated AKT and MAPKs and increased AP-1 DNA binding in a redox-sensitive manner. Ang II stimulated DNA synthesis, cell migration, procollagen alpha1(I) mRNA expression, and secretion of TGF-beta1 and inflammatory cytokines. These effects were attenuated by N-acetylcysteine and diphenylene iodonium, an NADPH oxidase inhibitor. Moreover, Ang II induced upregulation of genes potentially involved in hepatic wound-healing response in a redox-sensitive manner, as assessed by microarray analysis. HSCs isolated from p47phox-/- mice displayed a blunted response to Ang II compared with WT cells. We also assessed the role of NADPH oxidase in experimental liver fibrosis. After bile duct ligation, p47phox-/- mice showed attenuated liver injury and fibrosis compared with WT counterparts. Moreover, expression of smooth muscle alpha-actin and expression of TGF-beta1 were reduced in p47phox-/- mice. Thus, NADPH oxidase mediates the actions of Ang II on HSCs and plays a critical role in liver fibrogenesis.
Department of Medicine, Columbia University College of Physicians and Surgeons, 622 West 168th Street, New York, New York 10032, USA. dab2106@columbia.edu
Ramon
R
Bataller
Robert F
RF
Schwabe
Youkyung H
YH
Choi
Liu
L
Yang
Yong Han
YH
Paik
Jeffrey
J
Lindquist
Ting
T
Qian
Robert
R
Schoonhoven
Curt H
CH
Hagedorn
John J
JJ
Lemasters
David A
DA
Brenner
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008106:Liver Cirrhosis, Experimental / Q000209:etiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D019255:NADPH Oxidases / Q000502:physiology*; D010750:Phosphoproteins / Q000502:physiology; D017382:Reactive Oxygen Species; D015398:Signal Transduction / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000378:metabolism
D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D000804:Angiotensin II; D004247:DNA; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D020928:Mitogen-Activated Protein Kinases