NAD(P)H oxidase plays a crucial role in PDGF-induced proliferation of hepatic stellate cells.
The proliferation of hepatic stellate cells (HSCs) is a critical step in hepatic fibrogenesis. Platelet-derived growth factor (PDGF) is the most potent mitogen for HSCs. We investigated the role of nonphagocytic NAD(P)H oxidase-derived reactive oxygen species (ROS) in PDGF-induced HSC proliferation. The human HSC line, LI-90 cells, murine primary-cultured HSCs, and PDGF-BB were used in this study. We examined the mechanism of PDGF-BB-induced HSC proliferation in relation to the role of a ROS scavenger and diphenylene iodonium, an inhibitor of NAD(P)H oxidase. We also measured ROS production with the aid of chemiluminescence. We showed that PDGF-BB induced proliferation of HSCs through the intracellular production of ROS. We also demonstrated that HSCs expressed key components of nonphagocytic NAD(P)H oxidase (p22phox, gp91phox, p47phox, and p67phox) at both the messenger RNA and protein levels. Diphenylene iodonium suppressed PDGF-BB-induced ROS production and HSC proliferation. Coincubation of H2O2 and PDGF-BB restored the proliferation of HSCs that was inhibited by diphenylene iodonium pretreatment. Phosphorylation of the mitogen-activated protein kinase (MAPK) family constitutes a signal transduction pathway of cell proliferation. Our data demonstrate that NAD(P)H oxidase-derived ROS induce HSC proliferation mainly through the phosphorylation of p38 MAPK. Moreover, an in vivo hepatic fibrosis model also supported the critical role of NAD(P)H oxidase in the activation and proliferation of HSCs. In conclusion, NAD(P)H oxidase is expressed in HSCs and produces ROS via activation of NAD(P)H oxidase in response to PDGF-BB. ROS further induce HSC proliferation through the phosphorylation of p38 MAPK.
Adachi
Tohru
T
Department of Gastroenterology, Course of Internal Medicine and Therapeutics, Yamagata University School of Medicine, Yamagata, Japan.
Togashi
Hitoshi
H
Suzuki
Akihiko
A
Kasai
Shigenobu
S
Ito
Junitsu
J
Sugahara
Kazuhiko
K
Kawata
Sumio
S
D000818:Animals; D000077214:Becaplermin; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008099:Liver / Q000166:cytology*; D008103:Liver Cirrhosis / Q000473:pathology; D051379:Mice; D019255:NADPH Oxidases / Q000378:metabolism / Q000502:physiology*; D009861:Onium Compounds / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011166:Porphyrins / Q000494:pharmacology; D020574:Proto-Oncogene Proteins c-sis; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D016166:Free Radical Scavengers; D007527:Isoenzymes; D009861:Onium Compounds; D010982:Platelet-Derived Growth Factor; D011166:Porphyrins; D020574:Proto-Oncogene Proteins c-sis; D017382:Reactive Oxygen Species; C480958:tetrakis(4-benzoic acid)porphyrin; D000077214:Becaplermin; C007517:diphenyleneiodonium; D019255:NADPH Oxidases; D048051:p38 Mitogen-Activated Protein Kinases