title: Transforming growth factor-beta1 induces Nox4 NAD(P)H oxidase and reactive oxygen species-dependent proliferation in human pulmonary artery smooth muscle cells.
abstract: Transforming growth factor-beta1 (TGF-beta1) is abundantly expressed in pulmonary hypertension, but its effect on the pulmonary circulation remains unsettled. We studied the consequences of TGF-beta1 stimulation on freshly isolated human pulmonary artery smooth muscle cells (HPASMC). TGF-beta1 initially promoted differentiation, with upregulated expression of smooth muscle contractile proteins. TGF-beta1 also induced expression of Nox4, the only NAD(P)H oxidase membrane homolog found in HPASMC, through a signaling pathway involving Smad 2/3 but not mitogen-activated protein (MAP) kinases. TGF-beta1 likewise increased production of reactive oxygen species (ROS), an effect significantly reduced by the NAD(P)H oxidase flavoprotein inhibitor diphenylene iodonium (DPI) and by Nox4 siRNAs. In the absence of TGF-beta1, Nox4 was present in freshly cultured cells but progressively lost with each passage in culture, paralleling a decrease in ROS production by HPASMC over time. At a later time point (72 h), TGF-beta1 promoted HPASMC proliferation in a manner partially inhibited by Nox4 small interfering RNA and dominant negative Smad 2/3, indicating that TGF-beta1 stimulates HPASMC growth in part by a redox-dependent mechanism mediated through induction of Nox4. HPASMC activation of the MAP kinases ERK1/2 was reduced by the NAD(P)H oxidase inhibitors DPI and 4-(2-aminoethyl)benzenesulfonyl fluoride, suggesting that TGF-beta1 may facilitate proliferation by upregulating Nox4 and ROS production, with transient oxidative inactivation of phosphatases and augmentation of growth signaling cascades. These findings suggest that Nox4 is the relevant Nox homolog in HPASMC. This is the first observation that TGF-beta1 regulates Nox4, with important implications for mechanisms of pulmonary vascular remodeling.
authors.affiliation: Div. of Respiratory, Critical Care and Occupational Pulmonary Medicine, Wintrobe 701, Univ. of Utah Medical Center, Salt Lake City, UT 84132, USA.
authors.forename: Anne
authors.initials: A
authors.lastname: Sturrock
authors.forename: Barbara
authors.initials: B
authors.lastname: Cahill
authors.forename: Kimberly
authors.initials: K
authors.lastname: Norman
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Huecksteadt
authors.forename: Kenneth
authors.initials: K
authors.lastname: Hill
authors.forename: Karl
authors.initials: K
authors.lastname: Sanders
authors.forename: S V
authors.initials: SV
authors.lastname: Karwande
authors.forename: James C
authors.initials: JC
authors.lastname: Stringham
authors.forename: David A
authors.initials: DA
authors.lastname: Bull
authors.forename: Martin
authors.initials: M
authors.lastname: Gleich
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Kennedy
authors.forename: John R
authors.initials: JR
authors.lastname: Hoidal
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000378:metabolism; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D051785:Smad Proteins / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
chemical_list: D003285:Contractile Proteins; D017382:Reactive Oxygen Species; D051785:Smad Proteins; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; D020928:Mitogen-Activated Protein Kinases