1432

MAPK14

Idiopathic pulmonary fibrosis is characterized by myofibroblast accumulation, extracellular matrix (ECM) remodeling, and excessive collagen deposition. ECM-producing myofibroblasts may originate from epithelial cells through epithelial to mesenchymal transition (EMT). TGF-beta1 is an inducer of EMT in pulmonary epithelial cells in vitro and in vivo, though the mechanisms are unclear. We hypothesized that TGF-beta1 induced EMT through Smad-dependent and -independent processes. To test this hypothesis, we studied the roles and mechanisms of TGF-beta1-induced Smad and p38 mitogen-activated protein kinase (MAPK) signaling in EMT-related changes in pulmonary epithelial cells. Exposure of pulmonary epithelial 1HAEo(-) cells to TGF-beta1 resulted in morphological and molecular changes of EMT over a 96-h period; loss of cell-cell contact, cell elongation, down-regulation of E-cadherin, up-regulation of fibronectin, and up-regulation of collagen I. Both Smad2/3 and p38 MAPK signaling pathways were activated by TGF-beta1. However, neither Smad2/3 nor p38 MAPK were required for the down-regulation of E-cadherin, yet p38 MAPK was associated with fibronectin up-regulation. Both Smad2/3 and p38 MAPK had a role in regulation of TGF-beta1-induced collagen expression. Furthermore, these data demonstrate that Smads and p38 MAPK differentially regulate EMT-related changes in pulmonary epithelial cells.CI - Copyright (c) 2010 Wiley-Liss, Inc.

epithelial-to-mesenchymal transition (EMT) of peritoneal mesothelial cells is a pathological process that occurs during peritoneal dialysis. EMT leads to peritoneal fibrosis, ultrafiltration failure and eventually to the discontinuation of therapy. Signaling pathways involved in mesothelial EMT are thus of great interest, but are mostly unknown. We used primary mesothelial cells from human omentum to analyze the role of the p38 MAPK signaling pathway in the induction of EMT. The use of specific inhibitors, a dominant-negative p38 mutant and lentiviral silencing of p38alpha demonstrated that p38 promotes E-cadherin expression both in untreated cells and in cells co-stimulated with the EMT-inducing stimuli transforming growth factor (TGF)-beta1 and interleukin (IL)-1beta. p38 inhibition also led to disorganization and downregulation of cytokeratin filaments and zonula occludens (ZO)-1, whereas expression of vimentin was increased. Analysis of transcription factors that repress E-cadherin expression showed that p38 blockade inhibited expression of Snail1 while increasing expression of Twist. Nuclear translocation and transcriptional activity of p65 NF-kappaB, an important inducer of EMT, was increased by p38 inhibition. Moreover, p38 inhibition increased the phosphorylation of TGF-beta-activated kinase 1 (TAK1), NF-kappaB and IkappaBalpha. The effect of p38 inhibition on E-cadherin expression was rescued by modulating the TAK1-NF-kappaB pathway. Our results demonstrate that p38 maintains E-cadherin expression by suppressing TAK1-NF-kappaB signaling, thus impeding the induction of EMT in human primary mesothelial cells. This represents a novel role of p38 as a brake or 'gatekeeper' of EMT induction by maintaining E-cadherin levels.

Transforming growth factor-beta1 (TGF-beta1), a potent inducer of epithelial-to-mesenchymal transition (EMT), upregulates the cold-inducible RNA-binding protein (CIRP). The link between CIRP and EMT, however, remains unknown. To determine the role of CIRP in EMT, we performed CIRP knockdown and overexpression experiments in in vitro TGF-beta1-induced EMT models. We found that CIRP overexpression promoted the downregulation of epithelial markers and the upregulation of mesenchymal markers after TGF-beta1 treatment for EMT induction. It also promoted cell migration and invasion, key features of EMT. In contrast, CIRP knockdown inhibited the downregulation of epithelial markers and the upregulation of mesenchymal markers after TGF-beta1 treatment for EMT induction. In addition, it also inhibited cell migration and invasion. Furthermore, we demonstrated that the RNA-recognition motif in CIRP is essential for the role of CIRP in EMT. At the downstream level, CIRP knockdown downregulated Snail, key transcriptional regulator of EMT, while CIRP overexpression upregulated it. We found out that the link between CIRP and Snail is mediated by ERK and p38 pathways. EMT is a critical component of carcinoma metastasis and invasion. As demonstrated in this study, the biological role of CIRP in EMT may explain why CIRP overexpression has been associated with a bad prognosis in cancer patients.CI - Copyright (c) 2016 Elsevier Inc. All rights reserved.

Idiopathic pulmonary fibrosis (IPF) is characterized by myofibroblast foci in lung parenchyma. Myofibroblasts are thought to originate from epithelial-to-mesenchymal transition (EMT). Wnt1 and lithium chloride (LiCl) induce EMT in alveolar epithelial cells (AECs), but the mechanisms are unclear. AECs were treated with Wnt1 and LiCl, respectively; morphological change and molecular changes of EMT, including E-cadherin, fibronectin, and vimentin, were observed. SB203580 was administrated to test the role of p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic signaling in EMT. Then AECs were treated with siRNAs targeting p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic to further test the effects of p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic, and the role was further confirmed by re-expression of p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic. At last P-catenin siRNA was used to test the role of beta-catenin in the EMT process and relationship of beta-catenin and p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic was concluded. Exposure of AECs to Wnt1 and LiCl resulted in upregulation of vimentin and fibronectin with subsequent downregulation of E-cadherin. Wnt1 and LiCl stimulated the p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic signaling pathways. Perturbing the p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic pathway either by SB203580 or through p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic siRNA blocked EMT and inhibited fibronetin synthesis, which were reversed by transfection of p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic expression plasmid. beta-catenin siRNA attenuated the EMT process and decreased p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic phosphorylation, indicating that beta-catenin is involved in the EMTrelated changes through regulation of p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic phosphorylation. These findings suggest that p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic participates in the pathogenesis of EMT through Wnt pathway and that p38 capital EM, Cyrilliccapital A, Cyrilliccapital ER, Cyrilliccapital KA, Cyrillic may be a novel target for IPF therapy.