Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells
<p>Abstract</p> <p>Background</p> <p>Transforming growth factor β1 (TGF-β1)-mediated epithelial mesenchymal transition (EMT) of alveolar epithelial cells (AEC) may contribute to lung fibrosis. Since PPARγ ligands have been shown to inhibit fibroblast activation by TGF-β...
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doaj-2332e6373516468580beebe18a0f33592020-11-25T01:37:21ZengBMCRespiratory Research1465-99212010-02-011112110.1186/1465-9921-11-21Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cellsDagher HayatTan XiahuiHutton Craig ABourke Jane E<p>Abstract</p> <p>Background</p> <p>Transforming growth factor β1 (TGF-β1)-mediated epithelial mesenchymal transition (EMT) of alveolar epithelial cells (AEC) may contribute to lung fibrosis. Since PPARγ ligands have been shown to inhibit fibroblast activation by TGF-β1, we assessed the ability of the thiazolidinediones rosiglitazone (RGZ) and ciglitazone (CGZ) to regulate TGF-β1-mediated EMT of A549 cells, assessing changes in cell morphology, and expression of cell adhesion molecules E-cadherin (epithelial cell marker) and N-cadherin (mesenchymal cell marker), and collagen 1α1 (COL1A1), CTGF and MMP-2 mRNA.</p> <p>Methods</p> <p>Serum-deprived A549 cells (human AEC cell line) were pre-incubated with RGZ and CGZ (1 - 30 μM) in the absence or presence of the PPARγ antagonist GW9662 (10 μM) before TGFβ-1 (0.075-7.5 ng/ml) treatment for up to 72 hrs. Changes in E-cadherin, N-cadherin and phosphorylated Smad2 and Smad3 levels were analysed by Western blot, and changes in mRNA levels including COL1A1 assessed by RT-PCR.</p> <p>Results</p> <p>TGFβ-1 (2.5 ng/ml)-induced reductions in E-cadherin expression were associated with a loss of epithelial morphology and cell-cell contact. Concomitant increases in N-cadherin, MMP-2, CTGF and COL1A1 were evident in predominantly elongated fibroblast-like cells. Neither RGZ nor CGZ prevented TGFβ1-induced changes in cell morphology, and PPARγ-dependent inhibitory effects of both ligands on changes in E-cadherin were only evident at submaximal TGF-β1 (0.25 ng/ml). However, both RGZ and CGZ inhibited the marked elevation of N-cadherin and COL1A1 induced by TGF-β1 (2.5 ng/ml), with effects on COL1A1 prevented by GW9662. Phosphorylation of Smad2 and Smad3 by TGF-β1 was not inhibited by RGZ or CGZ.</p> <p>Conclusions</p> <p>RGZ and CGZ inhibited profibrotic changes in TGF-β1-stimulated A549 cells independently of inhibition of Smad phosphorylation. Their inhibitory effects on changes in collagen I and E-cadherin, but not N-cadherin or CTGF, appeared to be PPARγ-dependent. Further studies are required to unravel additional mechanisms of inhibition of TGF-β1 signalling by thiazolidinediones and their implications for the contribution of EMT to lung fibrosis.</p> http://respiratory-research.com/content/11/1/21 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Dagher Hayat Tan Xiahui Hutton Craig A Bourke Jane E |
spellingShingle |
Dagher Hayat Tan Xiahui Hutton Craig A Bourke Jane E Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells Respiratory Research |
author_facet |
Dagher Hayat Tan Xiahui Hutton Craig A Bourke Jane E |
author_sort |
Dagher Hayat |
title |
Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells |
title_short |
Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells |
title_full |
Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells |
title_fullStr |
Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells |
title_full_unstemmed |
Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells |
title_sort |
effects of pparγ ligands on tgf-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells |
publisher |
BMC |
series |
Respiratory Research |
issn |
1465-9921 |
publishDate |
2010-02-01 |
description |
<p>Abstract</p> <p>Background</p> <p>Transforming growth factor β1 (TGF-β1)-mediated epithelial mesenchymal transition (EMT) of alveolar epithelial cells (AEC) may contribute to lung fibrosis. Since PPARγ ligands have been shown to inhibit fibroblast activation by TGF-β1, we assessed the ability of the thiazolidinediones rosiglitazone (RGZ) and ciglitazone (CGZ) to regulate TGF-β1-mediated EMT of A549 cells, assessing changes in cell morphology, and expression of cell adhesion molecules E-cadherin (epithelial cell marker) and N-cadherin (mesenchymal cell marker), and collagen 1α1 (COL1A1), CTGF and MMP-2 mRNA.</p> <p>Methods</p> <p>Serum-deprived A549 cells (human AEC cell line) were pre-incubated with RGZ and CGZ (1 - 30 μM) in the absence or presence of the PPARγ antagonist GW9662 (10 μM) before TGFβ-1 (0.075-7.5 ng/ml) treatment for up to 72 hrs. Changes in E-cadherin, N-cadherin and phosphorylated Smad2 and Smad3 levels were analysed by Western blot, and changes in mRNA levels including COL1A1 assessed by RT-PCR.</p> <p>Results</p> <p>TGFβ-1 (2.5 ng/ml)-induced reductions in E-cadherin expression were associated with a loss of epithelial morphology and cell-cell contact. Concomitant increases in N-cadherin, MMP-2, CTGF and COL1A1 were evident in predominantly elongated fibroblast-like cells. Neither RGZ nor CGZ prevented TGFβ1-induced changes in cell morphology, and PPARγ-dependent inhibitory effects of both ligands on changes in E-cadherin were only evident at submaximal TGF-β1 (0.25 ng/ml). However, both RGZ and CGZ inhibited the marked elevation of N-cadherin and COL1A1 induced by TGF-β1 (2.5 ng/ml), with effects on COL1A1 prevented by GW9662. Phosphorylation of Smad2 and Smad3 by TGF-β1 was not inhibited by RGZ or CGZ.</p> <p>Conclusions</p> <p>RGZ and CGZ inhibited profibrotic changes in TGF-β1-stimulated A549 cells independently of inhibition of Smad phosphorylation. Their inhibitory effects on changes in collagen I and E-cadherin, but not N-cadherin or CTGF, appeared to be PPARγ-dependent. Further studies are required to unravel additional mechanisms of inhibition of TGF-β1 signalling by thiazolidinediones and their implications for the contribution of EMT to lung fibrosis.</p> |
url |
http://respiratory-research.com/content/11/1/21 |
work_keys_str_mv |
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