Dataset Information

Analysis of the TGF?-induced program in primary airway epithelial cells shows essential role of NF-?B/RelA signaling network in type II epithelial mesenchymal transition.

ABSTRACT: The airway epithelial cell plays a central role in coordinating the pulmonary response to injury and inflammation. Here, transforming growth factor-? (TGF?) activates gene expression programs to induce stem cell-like properties, inhibit expression of differentiated epithelial adhesion proteins and express mesenchymal contractile proteins. This process is known as epithelial mesenchymal transition (EMT); although much is known about the role of EMT in cellular metastasis in an oncogene-transformed cell, less is known about Type II EMT, that occurring in normal epithelial cells. In this study, we applied next generation sequencing (RNA-Seq) in primary human airway epithelial cells to understand the gene program controlling Type II EMT and how cytokine-induced inflammation modifies it.Generalized linear modeling was performed on a two-factor RNA-Seq experiment of 6 treatments of telomerase immortalized human small airway epithelial cells (3 replicates). Using a stringent cut-off, we identified 3,478 differentially expressed genes (DEGs) in response to EMT. Unbiased transcription factor enrichment analysis identified three clusters of EMT regulators, one including SMADs/TP63 and another NF-?B/RelA. Surprisingly, we also observed 527 of the EMT DEGs were also regulated by the TNF-NF-?B/RelA pathway. This Type II EMT program was compared to Type III EMT in TGF? stimulated A549 alveolar lung cancer cells, revealing significant functional differences. Moreover, we observe that Type II EMT modifies the outcome of the TNF program, reducing IFN signaling and enhancing integrin signaling. We confirmed experimentally that TGF?-induced the NF-?B/RelA pathway by observing a 2-fold change in NF-?B/RelA nuclear translocation. A small molecule IKK inhibitor blocked TGF?-induced core transcription factor (SNAIL1, ZEB1 and Twist1) and mesenchymal gene (FN1 and VIM) expression.These data indicate that NF-?B/RelA controls a SMAD-independent gene network whose regulation is required for initiation of Type II EMT. Type II EMT dramatically affects the induction and kinetics of TNF-dependent gene networks.

SUBMITTER: Tian B

PROVIDER: S-EPMC4506436 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Analysis of the TGFβ-induced program in primary airway epithelial cells shows essential role of NF-κB/RelA signaling network in type II epithelial mesenchymal transition.

Tian Bing B Li Xueling X Kalita Mridul M Widen Steven G SG Yang Jun J Bhavnani Suresh K SK Dang Bryant B Kudlicki Andrzej A Sinha Mala M Kong Fanping F Wood Thomas G TG Luxon Bruce A BA Brasier Allan R AR

BMC genomics 20150718

<h4>Background</h4>The airway epithelial cell plays a central role in coordinating the pulmonary response to injury and inflammation. Here, transforming growth factor-β (TGFβ) activates gene expression programs to induce stem cell-like properties, inhibit expression of differentiated epithelial adhesion proteins and express mesenchymal contractile proteins. This process is known as epithelial mesenchymal transition (EMT); although much is known about the role of EMT in cellular metastasis in an ...[more]

PMID: 26187636

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Project description:The airway epithelial cell plays a central role in coordinating pulmonary response to injury and inflammation. Here, transforming growth factor-b (TGFb) activates gene expression programs to induce stem cell-like properties, inhibit expression of differentiated epithelial adhesion proteins and express mesenchymal contractile proteins. This process is known as epithelial mesenchymal transition (EMT); although much is known about the role of EMT in cellular metastasis in an oncogene-transformed cell, less is known about Type II EMT, that occurring in normal epithelial cells. In this study, we applied next generation sequencing (RNA-seq) in primary human airway epithelial cells to understand the gene program controlling Type II EMT and how cytokine-induced inflammation modifies it. Generalized linear modeling was performed on a two-factor RNA-seq experiment of 6 treatments of telomerase immortalized human small airway epithelial cells (3 replicates). Using a stringent cut-off, we identified 3,478 differentially expressed genes (DEGs) in response to EMT. Unbiased transcription factor enrichment analysis identified three clusters of EMT regulators, one including SMADs/TP63 and another NF-kB/RelA. Surprisingly, we also observed 527 of the EMT DEGs were also regulated by the TNF-NF-kB/RelA pathway. This Type II EMT program was compared to Type III EMT in TGFb stimulated A549 alveolar lung cancer cells, revealing significant functional differences. Moreover, we observe that Type II EMT modifies the outcome of the TNF program, reducing IFN signaling and enhancing integrin signaling. We confirmed experimentally that TGFb-induced the NF-kB/RelA pathway by observing a 2-fold change in NF-kB/RelA nuclear translocation. A small molecule IKK inhibitor blocked TGFb-induced core transcription factor (SNAIL1, ZEB1 and Twist1) and mesenchymal gene (FN1 and VIM) expression. These data indicate that NF-kB/RelA controls a SMAD-independent gene network whose regulation is required for initiation of Type II EMT. Type II EMT dramatically affects the induction and kinetics of TNF-dependent gene networks.

Project description:The airway mucosa expresses protective interferon (IFN) and inflammatory cytokines in response to respiratory syncytial virus (RSV) infection. In this study, we examine the role of bromodomain containing 4 (BRD4) in mediating this innate immune response in human small airway epithelial cells. We observe that RSV induces BRD4 to complex with NF-κB/RelA. BRD4 is functionally required for expression of the NF-κB-dependent inflammatory gene regulatory network (GRN), including the IFN response factor 1 (IRF1) and IRF7, which mediate a cross talk pathway for RIG-I upregulation. Mechanistically, BRD4 is required for cyclin-dependent kinase 9 (CDK9) recruitment and phospho-Ser 2 carboxy-terminal domain (CTD) RNA polymerase (Pol) II formation on the promoters of IRF1, IRF7, and RIG-I, producing their enhanced expression by transcriptional elongation. We also find that BRD4 independently regulates CDK9/phospho-Ser 2 CTD RNA Pol II recruitment to the IRF3-dependent IFN-stimulated genes (ISGs). In vivo, poly(I·C)-induced neutrophilia and mucosal chemokine production are blocked by a small-molecule BRD4 bromodomain inhibitor. Similarly, BRD4 inhibition reduces RSV-induced neutrophilia, mucosal CXC chemokine expression, activation of the IRF7-RIG-I autoamplification loop, mucosal IFN expression, and airway obstruction. RSV infection activates BRD4 acetyltransferase activity on histone H3 Lys (K) 122, demonstrating that RSV infection activates BRD4 in vivo These data validate BRD4 as a major effector of RSV-induced inflammation and disease. BRD4 is required for coupling NF-κB to expression of inflammatory genes and the IRF-RIG-I autoamplification pathway and independently facilitates antiviral ISG expression. BRD4 inhibition may be a strategy to reduce exuberant virus-induced mucosal airway inflammation.IMPORTANCE In the United States, 2.1 million children annually require medical attention for RSV infections. A first line of defense is the expression of the innate gene network by infected epithelial cells. Expression of the innate response requires the recruitment of transcriptional elongation factors to rapidly induce innate response genes through an unknown mechanism. We discovered that RSV infection induces a complex of bromodomain containing 4 (BRD4) with NF-κB and cyclin-dependent kinase 9 (CDK9). BRD4 is required for stable CDK9 binding, phospho-Ser 2 RNA Pol II formation, and histone acetyltransferase activity. Inhibition of BRD4 blocks Toll-like receptor 3 (TLR3)-dependent neutrophilia and RSV-induced inflammation, demonstrating its importance in the mucosal innate response in vivo Our study shows that BRD4 plays a central role in inflammation and activation of the IRF7-RIG-I amplification loop vital for mucosal interferon expression. BRD4 inhibition may be a strategy for modulating exuberant mucosal airway inflammation.

Dataset Information

Analysis of the TGF?-induced program in primary airway epithelial cells shows essential role of NF-?B/RelA signaling network in type II epithelial mesenchymal transition.

Publications

Analysis of the TGFβ-induced program in primary airway epithelial cells shows essential role of NF-κB/RelA signaling network in type II epithelial mesenchymal transition.

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