Oxidative modification of nuclear mitogen-activated protein kinase phosphatase 1 is involved in transforming growth factor beta1-induced expression of plasminogen activator inhibitor 1 in fibroblasts.
Transforming growth factor beta (TGF-beta) stimulates reactive oxygen species (ROS) production in various cell types, which mediates many of the effects of TGF-beta. The molecular mechanisms whereby TGF-beta increases ROS production and ROS modulate the signaling processes of TGF-beta, however, remain poorly defined. In this study, we show that TGF-beta1 stimulates NADPH oxidase 4 (Nox4) expression and ROS generation in the nucleus of murine embryo fibroblasts (NIH3T3 cells). This is associated with an increase in protein thiol modification and inactivation of MAPK phosphatase 1 (MKP-1), a nuclear phosphatase. Furthermore, knockdown of MKP-1 using small interfering RNA enhances TGF-beta1-induced phosphorylation of JNK and p38 as well as the expression of plasminogen activator inhibitor 1 (PAI-1), a TGF-beta-responsive gene involved in the pathogenesis of many diseases. Knockdown of Nox4 with Nox4 small interfering RNA, on the other hand, reduces TGF-beta1-stimulated ROS production, p38 phosphorylation, and PAI-1 expression. TGF-beta also increased the nuclear level of Nox4 protein as well as PAI-1 expression in human lung fibroblasts (CCL-210 cells), suggesting that TGF-beta may induce PAI-1 expression by a similar mechanism in human lung fibroblasts. In summary, in this study we have identified nuclear MAPK phosphatase MKP-1 as a novel molecular target of ROS in TGF-beta signaling pathways. Our data suggest that increased generation of ROS by Nox4 mediates TGF-beta1-induced PAI-1 gene expression at least in part through oxidative modification and inhibition of MKP-1 leading to a sustained activation of JNK and p38 MAPKs.
Department of Environmental Health Sciences, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. rliu@uab.edu
Rui-Ming
RM
Liu
Jinah
J
Choi
Jian-He
JH
Wu
Kimberly A
KA
Gaston Pravia
Karen M
KM
Lewis
Jeffrey D
JD
Brand
N S Reyes
NS
Mochel
David M
DM
Krzywanski
J David
JD
Lambeth
James S
JS
Hagood
Henry Jay
HJ
Forman
Victor J
VJ
Thannickal
Edward M
EM
Postlethwait
D000818:Animals; D054638:Dual Specificity Phosphatase 1 / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis* / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
D009687:Nuclear Proteins; D017395:Plasminogen Activator Inhibitor 1; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C051321:SERPINE1 protein, human; D053773:Transforming Growth Factor beta1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; C422943:Nox4 protein, mouse; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse