Dataset Information

BRD4 mediates NF-?B-dependent epithelial-mesenchymal transition and pulmonary fibrosis via transcriptional elongation.

ABSTRACT: Chronic epithelial injury triggers a TGF-?-mediated cellular transition from normal epithelium into a mesenchymal-like state that produces subepithelial fibrosis and airway remodeling. Here we examined how TGF-? induces the mesenchymal cell state and determined its mechanism. We observed that TGF-? stimulation activates an inflammatory gene program controlled by the NF-?B/RelA signaling pathway. In the mesenchymal state, NF-?B-dependent immediate-early genes accumulate euchromatin marks and processive RNA polymerase. This program of immediate-early genes is activated by enhanced expression, nuclear translocation, and activating phosphorylation of the NF-?B/RelA transcription factor on Ser276, mediated by a paracrine signal. Phospho-Ser276 RelA binds to the BRD4/CDK9 transcriptional elongation complex, activating the paused RNA Pol II by phosphorylation on Ser2 in its carboxy-terminal domain. RelA-initiated transcriptional elongation is required for expression of the core epithelial-mesenchymal transition transcriptional regulators SNAI1, TWIST1, and ZEB1 and mesenchymal genes. Finally, we observed that pharmacological inhibition of BRD4 can attenuate experimental lung fibrosis induced by repetitive TGF-? challenge in a mouse model. These data provide a detailed mechanism for how activated NF-?B and BRD4 control epithelial-mesenchymal transition initiation and transcriptional elongation in model airway epithelial cells in vitro and in a murine pulmonary fibrosis model in vivo. Our data validate BRD4 as an in vivo target for the treatment of pulmonary fibrosis associated with inflammation-coupled remodeling in chronic lung diseases.

SUBMITTER: Tian B

PROVIDER: S-EPMC5206405 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

BRD4 mediates NF-κB-dependent epithelial-mesenchymal transition and pulmonary fibrosis via transcriptional elongation.

Tian Bing B Zhao Yingxin Y Sun Hong H Zhang Yueqing Y Yang Jun J Brasier Allan R AR

American journal of physiology. Lung cellular and molecular physiology 20161028 6

Chronic epithelial injury triggers a TGF-β-mediated cellular transition from normal epithelium into a mesenchymal-like state that produces subepithelial fibrosis and airway remodeling. Here we examined how TGF-β induces the mesenchymal cell state and determined its mechanism. We observed that TGF-β stimulation activates an inflammatory gene program controlled by the NF-κB/RelA signaling pathway. In the mesenchymal state, NF-κB-dependent immediate-early genes accumulate euchromatin marks and proc ...[more]

PMID: 27793799

Similar Datasets

Project description:Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease with no effective treatment. The epithelial-mesenchymal transition (EMT) is a critical stage during the development of fibrosis. To assess the effect of sulforaphane (SFN) on the EMT and fibrosis using an in vitro transforming growth factor (TGF)-?1-induced model and an in vivo bleomycin (BLM)-induced model.In vitro studies, cell viability, and cytotoxicity were measured using a Cell Counting Kit-8. The functional TGF-?1-induced EMT and fibrosis were assessed using western blotting and a quantitative real-time polymerase chain reaction. The lungs were analyzed histopathologically in vivo using hematoxylin and eosin and Masson's trichrome staining. The BLM-induced fibrosis was characterized by western blotting and immunohistochemical analyses for fibronectin, TGF-?1, E-cadherin (E-cad), and ?-smooth muscle actin (SMA) in lung tissues.SFN reversed mesenchymal-like changes induced by TGF-?1 and restored cells to their epithelial-like morphology. The results confirmed that the expression of the epithelial marker, E-cadherin, increased after SFN treatment, while expression of the mesenchymal markers, N-cadherin, vimentin, and ?-SMA decreased in A549 cells after SFN treatment. In addition, SFN inhibited TGF-?1-induced mRNA expression of the EMT-related transcription factors, Slug, Snail, and Twist. The SFN treatment attenuated TGF-?1-induced expression of fibrosis-related proteins, such as fibronection, collagen I, collagen IV, and ?-SMA in MRC-5 cells. Furthermore, SFN reduced the TGF-?1-induced phosphorylation of SMAD2/3 protein in A549 cells and MRC-5 cells. BLM induced fibrosis in mouse lungs that was also attenuated by SFN treatment, and SFN treatment decreased BLM-induced fibronectin expression, TGF-?1 expression, and the levels of collagen I in the lungs of mice.SFN showed a significant anti-fibrotic effect in TGF-?-treated cell lines and BLM-induced fibrosis in mice. These findings showed that SFN has anti-fibrotic activity that may be considered in the treatment of IPF.

Dataset Information

BRD4 mediates NF-?B-dependent epithelial-mesenchymal transition and pulmonary fibrosis via transcriptional elongation.

Publications

BRD4 mediates NF-κB-dependent epithelial-mesenchymal transition and pulmonary fibrosis via transcriptional elongation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets