Nox4 mediates TGF-beta1-induced retinoblastoma protein phosphorylation, proliferation, and hypertrophy in human airway smooth muscle cells

• Published in: American journal of physiology. Lung cellular and molecular physiology Vol. 292; no. 6; pp. L1543 - L1555
• Main Authors: Sturrock, Anne, Huecksteadt, Thomas P, Norman, Kimberly, Sanders, Karl, Murphy, Thomas M, Chitano, Pasquale, Wilson, Kimberly, Hoidal, John R, Kennedy, Thomas P
• Format: Journal Article
• Language: English
• Published: United States 01.06.2007
• Subjects: Activins - metabolism; Activins - pharmacology; Asthma - metabolism; Asthma - pathology; Bronchi - cytology; CDC2 Protein Kinase - metabolism; Cell Division - drug effects; Cell Division - physiology; Cell Nucleus - enzymology; Cells, Cultured; Eukaryotic Initiation Factor-4E - metabolism; Humans; Hypertrophy; Myocytes, Smooth Muscle - cytology; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - enzymology; NADPH Oxidase 4; NADPH Oxidases - genetics; NADPH Oxidases - metabolism; Oxidation-Reduction; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation; Protein Biosynthesis - physiology; Proto-Oncogene Proteins c-myc - metabolism; Reactive Oxygen Species - metabolism; Retinoblastoma Protein - metabolism; Signal Transduction - drug effects; Signal Transduction - physiology; Smad3 Protein - metabolism; Transfection; Transforming Growth Factor beta1 - metabolism; Transforming Growth Factor beta1 - pharmacology
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00430.2006

1 Division of Respiratory, Critical Care and Occupational Pulmonary Medicine, University of Utah Health Sciences Center and Veterans Administration Medical Center, Salt Lake City, Utah; 2 Division of Pediatric Pulmonary Diseases, Duke University Medical Center, Durham, North Carolina; and 3 Department of Biology, Winthrop University, Rock Hill, South Carolina Submitted 31 October 2006 ; accepted in final form 27 February 2007 Transforming growth factor- 1 (TGF- 1) plays a pivotal role in increasing airway smooth muscle mass in severe asthma by inducing proliferation and hypertrophy of human airway smooth muscle. The mechanism(s) for these effects of TGF- 1 have not been fully elucidated. In this study, we demonstrate that TGF- 1 is a potent inducer of expression of the nonphagocyte NAD(P)H oxidase catalytic homolog Nox4, diphenylene iodonium-inhibitable reactive oxygen species production, proliferation, and hypertrophy in cultured human airway smooth muscle cells. By confocal microscopy, TGF- 1-induced Nox4 was localized with the endoplasmic reticulum and the nucleus, implying a role for Nox4 in regulation of both the cell cycle and protein synthesis. Consistent with this hypothesis, TGF- 1 increased retinoblastoma protein phosphorylation at both Ser807/811 and Ser780. Silencing Nox4 prevented TGF- 1-mediated retinoblastoma protein phosphorylation, proliferation, and cell hypertrophy. TGF- 1 also increased phosphorylation of eukaryotic translation initiation factor 4E binding protein-1 at Thr37/46, and this was likewise blocked by silencing Nox4. This is the first report to suggest a functional role for Nox4 in cell cycle transition and to demonstrate that Nox4 influences the pathobiochemistry of asthma by generating reactive oxygen species that promote TGF- 1-induced proliferation and hypertrophy of human airway smooth muscle. Myc; cdc2; eukaryotic translation initiation factor 4E binding protein-1; nicotinamide adenine dinucleotide phosphate oxidase; reactive oxygen species; translation Address for reprint requests and other correspondence: T. P. Kennedy, Division of Respiratory, Critical Care, and Occupational Pulmonary Medicine, Wintrobe 701, Univ. of Utah Medical Center, 26 North 1900 East, Salt Lake City, UT 84132 (e-mail: Thomas.Kennedy{at}hsc.utah.edu )