Molecular mechanisms of TGF-(beta) antagonism by interferon (gamma) and cyclosporine A in lung fibroblasts.
Lung fibrosis is a fatal condition of excess extracellular matrix (ECM) deposition associated with increased transforming growth factor beta (TGF-beta) activity. Although much is known about its pathological features, our understanding of the signal transduction pathways resulting in increased ECM and collagen deposition in response to TGF-beta is still incompletely defined. We have previously reported that a JunD homodimer of the transcription factor AP-1 is specifically activated by TGF-beta in lung fibroblasts. Here we demonstrate that JunD is also specifically required for TGF-beta-induced effects. Antisense against JunD, but not c-fos or c-jun, significantly inhibited collagen deposition in response to TGF-beta in primary human lung fibroblasts. We then investigated the ability of pharmacological agents to inhibit TGF-beta-induced signaling and collagen deposition. Cs-A and IFN-gamma, but not glucocorticoids, cyclophosphamide, or azathioprine, inhibited TGF-beta-induced signaling, as assessed by luciferase reporter gene assays, and collagen deposition. TGF-beta antagonism by Cs-A was associated with direct inhibition of JunD activation, as demonstrated by electrophoretic mobility shift analyses. In contrast, the effects of IFN-gamma required signal transducer and activator of transcription (STAT)-1. We thus identify the JunD isoform of AP-1 as an essential mediator of TGF-beta-induced effects in lung fibroblasts. TGF-beta-induced signaling and collagen deposition are efficiently antagonized by Cs-A and IFN-gamma treatment, both of which exhibit distinct molecular mechanisms of action. These observations therefore offer novel targets for future therapy of fibrotic lung disease.
Eickelberg
O
O
Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520-8023, USA. oliver.eickelberg@yale.edu
Pansky
A
A
Koehler
E
E
Bihl
M
M
Tamm
M
M
Hildebrand
P
P
Perruchoud
A P
AP
Kashgarian
M
M
Roth
M
M
D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005109:Extracellular Matrix / Q000502:physiology; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D008168:Lung / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008954:Models, Biological; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics* / Q000378:metabolism; D011658:Pulmonary Fibrosis / Q000378:metabolism* / Q000473:pathology; D050794:STAT1 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism
D004268:DNA-Binding Proteins; D016376:Oligonucleotides, Antisense; D016755:Proto-Oncogene Proteins c-jun; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D007371:Interferon-gamma; D016572:Cyclosporine; D003094:Collagen