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Activation of Smad-mediated TGF-? signaling triggers epithelial-mesenchymal transitions in murine cloned corneal progenitor cells.

ABSTRACT: Epithelial-mesenchymal transition (EMT), via activation of Wnt signaling, is prevailing in embryogenesis, but postnatally it only occurs in pathological processes, such as in tissue fibrosis and tumor metastasis. Our prior studies led us to speculate that EMT might be involved in the loss of limbal epithelial stem cells in explant cultures. To examine this hypothesis, we successfully grew murine corneal/limbal epithelial progenitors by prolonging the culture time and by seeding at a low density in a serum-free medium. Single cell-derived clonal growth was accompanied by a gradient of Wnt signaling activity, from the center to the periphery, marked by a centrifugal loss of E-cadherin and ?-catenin from intercellular junctions, coupled with nuclear translocation of ?-catenin and LEF-1. Large-colony-forming efficiency at central location of colony was higher than peripheral location. Importantly, there was also progressive centrifugal differentiation, with positive K14 keratin expression and the loss of p63 and PCNA nuclear staining, and irreversible EMT, evidenced by cytoplasmic expression of ?-SMA and nuclear localization of S100A4; and by nuclear translocation of Smad4. Furthermore, cytoplasmic expression of ?-SMA was promoted by high-density cultures and their conditioned media, which contained cell density-dependent levels of TGF-?1, TGF-?2, GM-CSF, and IL-1?. Exogenous TGF-?1 induced ?-SMA positive cells in a low-density culture, while TGF-?1 neutralizing antibody partially inhibited ?-SMA expression in a high-density culture. Collectively, these results indicate that irreversible EMT emerges in the periphery of clonal expansion where differentiation and senescence of murine corneal/limbal epithelial progenitors occurs as a result of Smad-mediated TGF-?-signaling.

SUBMITTER: Kawakita T

PROVIDER: S-EPMC5775751 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Activation of Smad-mediated TGF-β signaling triggers epithelial-mesenchymal transitions in murine cloned corneal progenitor cells.

Kawakita Tetsuya T Espana Edgar M EM Higa Kazunari K Kato Naoko N Li Wei W Tseng Scheffer C G SC

Journal of cellular physiology 20130101 1

Epithelial-mesenchymal transition (EMT), via activation of Wnt signaling, is prevailing in embryogenesis, but postnatally it only occurs in pathological processes, such as in tissue fibrosis and tumor metastasis. Our prior studies led us to speculate that EMT might be involved in the loss of limbal epithelial stem cells in explant cultures. To examine this hypothesis, we successfully grew murine corneal/limbal epithelial progenitors by prolonging the culture time and by seeding at a low density ...[more]

PMID: 22674610

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Project description:AimPaeoniflorin has shown to attenuate bleomycin-induced pulmonary fibrosis (PF) in mice. Because the epithelial-mesenchymal transition (EMT) in type 2 lung endothelial cells contributes to excessive fibroblasts and myofibroblasts during multiple fibrosis of tissues, we investigated the effects of paeoniflorin on TGF-? mediated pulmonary EMT in bleomycin-induced PF mice.MethodsPF was induced in mice by intratracheal instillation of bleomycin (5 mg/kg). The mice were orally treated with paeoniflorin or prednisone for 21 d. After the mice were sacrificed, lung tissues were collected for analysis. An in vitro EMT model was established in alveolar epithelial cells (A549 cells) incubated with TGF-?1 (2 ng/mL). EMT identification and the expression of related proteins were performed using immunohistochemistry, transwell assay, ELISA, Western blot and RT-qPCR.ResultsIn PF mice, paeoniflorin (50, 100 mg·kg(-1)·d(-1)) or prednisone (6 mg·kg(-1)·d(-1)) significantly decreased the expression of FSP-1 and ?-SMA, and increased the expression of E-cadherin in lung tissues. In A549 cells, TGF-?1 stimulation induced EMT, as shown by the changes in cell morphology, the increased cell migration, and the increased vimentin and ?-SMA expression as well as type I and type III collagen levels, and by the decreased E-cadherin expression. In contrast, effects of paeoniflorin on EMT disappeared when the A549 cells were pretreated with TGF-?1 for 24 h. TGF-?1 stimulation markedly increased the expression of Snail and activated Smad2/3, Akt, ERK, JNK and p38 MAPK in A549 cells. Co-incubation with paeoniflorin (1-30 ?mol/L) dose-dependently attenuated TGF-?1-induced expression of Snail and activation of Smad2/3, but slightly affected TGF-?1-induced activation of Akt, ERK, JNK and p38 MAPK. Moreover, paeoniflorin markedly increased Smad7 level, and decreased ALK5 level in A549 cells.ConclusionPaeoniflorin suppresses the early stages of TGF-? mediated EMT in alveolar epithelial cells, likely by decreasing the expression of the transcription factors Snail via a Smad-dependent pathway involving the up-regulation of Smad7.

Project description:An altered liver microenvironment characterized by a dysregulated extracellular matrix (ECM) supports the development and progression of hepatocellular carcinoma (HCC). The development of experimental platforms able to reproduce these physio-pathological conditions is essential in order to identify and validate new therapeutic targets for HCC. The aim of this work was to validate a new in vitro model based on engineering three-dimensional (3D) healthy and cirrhotic human liver scaffolds with HCC cells recreating the micro-environmental features favoring HCC. Healthy and cirrhotic human livers ECM scaffolds were developed using a high shear stress oscillation-decellularization procedure. The scaffolds bio-physical/bio-chemical properties were analyzed by qualitative and quantitative approaches. Cirrhotic 3D scaffolds were characterized by biomechanical properties and microarchitecture typical of the native cirrhotic tissue. Proteomic analysis was employed on decellularized 3D scaffolds and showed specific enriched proteins in cirrhotic ECM in comparison to healthy ECM proteins. Cell repopulation of cirrhotic scaffolds highlighted a unique up-regulation in genes related to epithelial to mesenchymal transition (EMT) and TGFβ signaling. This was also supported by the presence and release of higher concentration of endogenous TGFβ1 in cirrhotic scaffolds in comparison to healthy scaffolds. Fibronectin secretion was significantly upregulated in cells grown in cirrhotic scaffolds in comparison to cells engrafted in healthy scaffolds. TGFβ1 induced the phosphorylation of canonical proteins Smad2/3, which was ECM scaffold-dependent. Important, TGFβ1-induced phosphorylation of Smad2/3 was significantly reduced and ECM scaffold-independent when pre/simultaneously treated with the TGFβ-R1 kinase inhibitor Galunisertib. In conclusion, the inherent features of cirrhotic human liver ECM micro-environment were dissected and characterized for the first time as key pro-carcinogenic components in HCC development.

Dataset Information

Activation of Smad-mediated TGF-? signaling triggers epithelial-mesenchymal transitions in murine cloned corneal progenitor cells.

Publications

Activation of Smad-mediated TGF-β signaling triggers epithelial-mesenchymal transitions in murine cloned corneal progenitor cells.

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