Smad3 deficiency attenuates bleomycin-induced  pulmonary fibrosis in mice

Zhao, Jingsong; Shi, Wei; Wang, Yanling; Chen, Hui; Bringas, Pablo; Datto, Michael B.; Frederick, Joshua P.; Wang, Xiaofan; Warburton, David

doi:10.1152/ajplung.00151.2001

Cited by 367 publications

(314 citation statements)

References 40 publications

Supporting

Mentioning

287

Contrasting

Unclassified

Order By: Relevance

“…p800CTGF-SEAP alone; P Ͻ 0.02), but without any effect on the levels in saline-treated cells ( Figure 3D). This indicates a strong contribution from this pathway to the expression of CTGF in this model of lung fibrosis, which is consistent with previously published observations in vivo (22,23). Our results suggest that the elevated level of CTGF present in fibroblasts cultured from fibrotic lungs contributes directly to the overproduction of type I collagen at the transcriptional level, and appears to mediate a significant part of bleomycininduced fibrotic processes.…”

Section: Contribution Of Ctgf To Col1a2 Promoter Activity Independentsupporting

confidence: 92%

“…Since TGF␤-induced collagen expression has been shown to involve Smad signaling in this model in vivo (22,23), we tested whether the CTGF effect was dependent on this pathway in vitro. Indeed, transfection of a Col1a2 promoter/reporter construct bearing a mutated SBE into bleomycin-derived fibroblasts confirmed that Smad signaling was involved in bleomycin-induced procollagen transcription in our system.…”

Section: Contribution Of Ctgf To Col1a2 Promoter Activity Independentmentioning

confidence: 99%

“…Binding of TGF␤ to the TGF␤ receptor complex induces phosphorylation of Smad3, which complexes with Smad4, translocates to the nucleus, and induces transcriptional responses by binding to Smad binding elements (SBEs) in target promoters (20). The fibroblasts present in bleomycin-induced fibrotic lesions show activated Smad3 (21), and bleomycin-induced lung fibrosis is reversed by application of an adenovirus encoding Smad7 (22) and is known to be less severe in Smad3-deficient mice (23). Increased CTGF expression has been observed in this mouse model (4,6).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Pivotal role of connective tissue growth factor in lung fibrosis: MAPK‐dependent transcriptional activation of type I collagen

Ponticos

Holmes

et al. 2009

Arthritis & Rheumatism

213

151

View full text Add to dashboard Cite

Objective. Connective tissue growth factor (CTGF; CCN2) is overexpressed in systemic sclerosis (SSc) and has been hypothesized to be a key mediator of the pulmonary fibrosis frequently observed in this disease. CTGF is induced by transforming growth factor ␤ (TGF␤) and is a mediator of some profibrotic effects of TGF␤ in vitro. This study was undertaken to investigate the role of CTGF in enhanced expression of type I collagen in bleomycin-induced lung fibrosis, and to delineate the mechanisms of action underlying the effects of CTGF on Col1a2 (collagen gene type I ␣2) in this mouse model and in human pulmonary fibroblasts.Methods. Transgenic mice that were carrying luciferase and ␤-galactosidase reporter genes driven by the Col1a2 enhancer/promoter and the CTGF promoter, respectively, were injected with bleomycin to induce lung fibrosis (or saline as control), and the extracted pulmonary fibroblasts were incubated with CTGF blocking agents. In vitro, transient transfection, promoter/ reporter constructs, and electrophoretic mobility shift assays were used to determine the mechanisms of action of CTGF in pulmonary fibroblasts.Results. In the mouse lung tissue, CTGF expression and promoter activity peaked 1 week after bleomycin challenge, whereas type I collagen expression and Col1a2 promoter activity peaked 2 weeks postchallenge. Fibroblasts isolated from the mouse lungs 14 days after bleomycin treatment retained a profibrotic expression pattern, characterized by greatly elevated levels of type I collagen and CTGF protein and increased promoter activity. In vitro, inhibition of CTGF by specific small interfering RNA and neutralizing antibodies reduced the collagen protein expression and Col1a2 promoter activity. Moreover, in vivo, anti-CTGF antibodies applied after bleomycin challenge significantly reduced the Col1a2 promoter activity by ϳ25%. The enhanced Col1a2 promoter activity in fibroblasts from bleomycintreated lungs was partly dependent on Smad signaling, whereas CTGF acted on the Col1a2 promoter by a mechanism that was independent of the Smad binding site, but was, instead, dependent on the ERK-1/2 and JNK MAPK pathways. The CTGF effect was mapped to the proximal promoter region surrounding the inverted CCAAT box, possibly involving CREB and c-Jun. In human lung fibroblasts, the human COL1A2 promoter responded in a similar manner, and the mechanisms of action also involved ERK-1/2 and JNK signaling.Conclusion. Our results clearly define a direct profibrotic effect of CTGF and demonstrate its contribution to lung fibrosis through transcriptional activation

show abstract

Section: Contribution Of Ctgf To Col1a2 Promoter Activity Independentsupporting

confidence: 92%

Section: Contribution Of Ctgf To Col1a2 Promoter Activity Independentmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Pivotal role of connective tissue growth factor in lung fibrosis: MAPK‐dependent transcriptional activation of type I collagen

Ponticos

Holmes

et al. 2009

Arthritis & Rheumatism

213

151

View full text Add to dashboard Cite

show abstract

“…For instance, it has helped to determine transforming growth factor (TGF) β as one of the key factors in the development of pulmonary fibrosis (J. Zhao et al, 2002). A number of novel (e.g.…”

Section: Bleomycinmentioning

confidence: 99%

The bleomycin animal model: A useful tool to investigate treatment options for idiopathic pulmonary fibrosis?

Moeller

Ask

Warburton

et al. 2008

The International Journal of Biochemistry & Cell Biology

Self Cite

822

724

View full text Add to dashboard Cite

Different animal models of pulmonary fibrosis have been developed to investigate potential therapies for idiopathic pulmonary fibrosis (IPF). The most common is the bleomycin model in rodents (mouse, rat and hamster). Over the years, numerous agents have been shown to inhibit fibrosis in this model. However, to date none of these compounds are used in the clinical management of IPF and none has shown a comparable antifibrotic effect in humans. We performed a systematic review of publications on drug efficacy studies in the bleomycin model to evaluate the value of this model regarding transferability to clinical use. Between 1980 and 2006 we identified 246 experimental studies describing beneficial antifibrotic compounds in the bleomycin model. In 221 of the studies we found enough details about the timing of drug application to allow inter-study comparison. 211 of those used a preventive regimen (drug given ≤ day 7 after last bleomycin application), only 10 were therapeutic trials (> 7 days after last bleomycin application). It is critical to distinguish between drugs interfering with the inflammatory and early fibrogenic response from those preventing progression of fibrosis, the latter likely much more meaningful for clinical application. All potential antifibrotic compounds should be evaluated in the phase of established fibrosis rather than in the early period of bleomycin-induced inflammation for assessment of its antifibrotic properties. Further care should be taken in extrapolation of drugs successfully tested in the bleomycin model due to partial reversibility of bleomycin induced fibrosis over time. The use of alternative and more robust animal models, which better reflect human IPF, is warranted.

show abstract

“…Smad3 appears to be a crucial element in the signal transduction pathways involved in wound healing and fibrosis (15)(16)(17). Smad3 null mice are protected against radiation-induced fibrosis of the skin (18), and a second Smad3 null line demonstrates attenuated lung fibrosis induced by bleomycin (19). Overexpression of Smad7, an inhibitor of the Smad pathway that prevents the phosphorylation and activation of Smad2 and Smad3, has also been shown to protect against fibrosis in a bleomycin model (20).…”

mentioning

confidence: 99%

Smad3 Null Mice Develop Airspace Enlargement and Are Resistant to TGF-β-Mediated Pulmonary Fibrosis

Bonniaud

Kolb

Galt

et al. 2004

The Journal of Immunology

350

258

View full text Add to dashboard Cite

Transforming growth factor-β1 plays a key role in the pathogenesis of pulmonary fibrosis, mediating extracellular matrix (ECM) gene expression through a series of intracellular signaling molecules, including Smad2 and Smad3. We show that Smad3 null mice (knockout (KO)) develop progressive age-related increases in the size of alveolar spaces, associated with high spontaneous presence of matrix metalloproteinases (MMP-9 and MMP-12) in the lung. Moreover, transient overexpression of active TGF-β1 in lungs, using adenoviral vector-mediated gene transfer, resulted in progressive pulmonary fibrosis in wild-type mice, whereas no fibrosis was seen in the lungs of Smad3 KO mice up to 28 days. Significantly higher levels of matrix components (procollagen 3A1, connective tissue growth factor) and antiproteinases (plasminogen activator inhibitor-1, tissue inhibitor of metalloproteinase-1) were detected in wild-type lungs 4 days after TGF-β1 administration, while no such changes were seen in KO lungs. These data suggest a pivotal role of the Smad3 pathway in ECM metabolism. Basal activity of the pathway is required to maintain alveolar integrity and ECM homeostasis, but excessive signaling through the pathway results in fibrosis characterized by inhibited degradation and enhanced ECM deposition. The Smad3 pathway is involved in pathogenic mechanisms mediating tissue destruction (lack of repair) and fibrogenesis (excessive repair).

show abstract

Smad3 deficiency attenuates bleomycin-induced pulmonary fibrosis in mice

Abstract: . Smad3 deficiency attenuates bleomycin-induced pulmonary fibrosis in mice.

Cited by 367 publications

References 40 publications

Pivotal role of connective tissue growth factor in lung fibrosis: MAPK‐dependent transcriptional activation of type I collagen

Pivotal role of connective tissue growth factor in lung fibrosis: MAPK‐dependent transcriptional activation of type I collagen

The bleomycin animal model: A useful tool to investigate treatment options for idiopathic pulmonary fibrosis?

Smad3 Null Mice Develop Airspace Enlargement and Are Resistant to TGF-β-Mediated Pulmonary Fibrosis

Contact Info

Product

Resources

About