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Salvianolic acid B prevents epithelial-to-mesenchymal transition through the TGF-beta1 signal transduction pathway in vivo and in vitro.

ABSTRACT: Salvianolic Acid B (Sal B) is a water-soluble component from Danshen (a traditional Chinese herb widely used for chronic renal diseases) with anti-oxidative and cell protective properties. Sal B also has potential protective effects on renal diseases. Tubular epithelial cells can undergo epithelial-to-mesenchymal transition (EMT), which plays an important role in the pathogenesis of renal interstitial fibrosis (RIF) and is mainly regulated by TGF-beta1/Smads pathway. The aims of the study are to investigate the effect of Sal B on tubular EMT in vivo and in vitro, and to elucidate its underlying mechanism against EMT related to TGF-beta1/Smads pathway.For in vivo experiments, RIF was induced in rats by oral administration of HgCl2 and prophylaxised with Sal B and vitamin E. The protein expression of E-cadherin was down-regulated, while the expression of alpha-SMA, TGF-beta1, TbetaR-I, p-Smad2/3 and the activity of matrix metalloproteinase-2 (MMP-2) were up-regulated in kidneys of model rats when compared with those of normal rats. In contrast, Sal B and vitamin E significantly attenuated the expression of alpha-SMA, TGF-beta1, TbetaR-I, p-Smad2/3, and MMP-2 activity, but increased E-cadherin expression. For in vitro experiments, HK-2 cells were incubated with TGF-beta1 to induce EMT, and the cells were co-cultured with 1 and 10 microM Sal B or SB-431542 (a specific inhibitor of TbetaR-I kinase). TGF-beta1 induced a typical EMT in HK-2 cells, while it was blocked by Sal B and SB-431542, as evidenced by blocking morphologic transformation, restoring E-cadherin and CK-18 expression, inhibiting alpha-SMA expression and F-actin reorganization, and down-regulating MMP-2/9 activities in TGF-beta1 mediated HK-2 cells. Furthermore, Sal B and SB-431542 profoundly down-regulated the expressions of TbetaR-I and p-Smad2/3 but prevented the decreased expression of Smad7 in TGF-beta1 stimulated HK-2 cells.Sal B can prevent tubular EMT in the fibrotic kidney induced by HgCl2 as well as HK-2 cells triggered by TGF-beta1, the mechanism of Sal B is closely related to the regulation of TGF-beta1/Smads pathway, manifested as the inhibition of TGF-beta1 expression, suppression of TbetaR-I expression and function, down-regulation of Smad2/3 phosphorylation, and restoration of the down-regulation of Smad7, as well as inhibition of MMP-2 activity.

SUBMITTER: Wang QL

PROVIDER: S-EPMC2874764 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Salvianolic acid B prevents epithelial-to-mesenchymal transition through the TGF-beta1 signal transduction pathway in vivo and in vitro.

Wang Qing-Lan QL Tao Yan-Yan YY Yuan Ji-Li JL Shen Li L Liu Cheng-Hai CH

BMC cell biology 20100505

<h4>Background</h4>Salvianolic Acid B (Sal B) is a water-soluble component from Danshen (a traditional Chinese herb widely used for chronic renal diseases) with anti-oxidative and cell protective properties. Sal B also has potential protective effects on renal diseases. Tubular epithelial cells can undergo epithelial-to-mesenchymal transition (EMT), which plays an important role in the pathogenesis of renal interstitial fibrosis (RIF) and is mainly regulated by TGF-beta1/Smads pathway. The aims ...[more]

PMID: 20441599

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Project description:Introduction:Krüppel-like factor 4 (KLF4) is considered one of the Yamanaka factors, and recently, we and others have shown that KLF4 is one of the transcription factors essential for reprogramming non-human corneal epithelial cells (HCECs) into HCECs. Since epithelial to mesenchymal transition (EMT) suppression is vital for homeostasis of HCECs via regulation of transcription factors, in this study, we aimed to investigate whether KLF4 prevents EMT in HCECs and to elucidate the underlying mechanism within the canonical TGF-? signalling pathway, which is involved in corneal epithelial wound healing. Methods:HCECs were collected from cadaver donors and cultivated. We generated KLF4-knockdown (KD) HCECs using siRNA transfection and analysed morphology, gene or protein expression, and endogenous TGF-? secretion. KLF4 was overexpressed using lentiviral KLF4 expression vectors and underwent protein expression analyses after TGF-?2 treatment. Results:KLF4-KD HCECs showed a fibroblastic morphology, downregulation of the epithelial markers, keratin 12 and keratin 14, and upregulation of the mesenchymal markers, fibronectin 1, vimentin, N-cadherin, and SLUG. Although E-cadherin expression remained unchanged in KLF4-KD HCECs, immunocytochemical analysis showed that E-cadherin-positive adherens junctions decreased in KLF4-KD HCECs as well as the decreased total protein levels of E-cadherin analysed by immunoblotting. Moreover, within the TGF-? canonical signalling pathway, TGF-?2 secretion by HCECs increased up to 5 folds, and several TGF-?-associated markers (TGFB1, TGFB2, TGFBR1, and TGFBR2) were significantly upregulated up to 6 folds in the KLF4-KD HCECs. SMAD2/3, the main signal transduction molecules of the TGF-? signalling pathway, were found to be localised in the nucleus of KLF4-KD HCECs. When KLF4 was overexpressed, cultivated HCECs showed upregulation of epithelial markers, keratin 14 and E-cadherin, indicating the contributory role of KLF4 in the homeostasis of human corneal epithelium in vivo. In addition, KLF4 overexpression in HCECs resulted in decreased SMAD2 phosphorylation and altered nuclear localisation of SMAD2/3, even after TGF-?2 treatment. Conclusions:These results show that KLF4 prevents EMT in HCECs and suggest a novel role of KLF4 as an endogenous TGF-?2 suppressor in the human corneal epithelium, thus highlighting the potential of KLF4 to prevent EMT and subsequent corneal fibrotic scar formation by attenuating TGF-? signalling.

Project description:BackgroundUnderstanding how mesenchymal cells arise from epithelial cells could have a strong impact in unveiling mechanisms of epithelial cell plasticity underlying kidney regeneration and repair. In primary human tubular epithelial cells (HUTEC) under different TGF beta 1 concentrations we had observed epithelial-to-mesenchymal transition (EMT) but not epithelial-myofibroblast transdifferentiation. We hypothesized that the process triggered by TGFbeta 1 could be a dedifferentiation event. The purpose of this study is to comprehensively delineate genetic programs associated with TGF beta 1-driven EMT in our in vitro model using gene expression profile on large-scale oligonucleotide microarrays.ResultsIn HUTEC under TGF beta 1 stimulus, 977 genes were found differentially expressed. Thirty genes were identified whose expression depended directly on TGF beta 1 concentration. By mapping the differentially expressed genes in the Human Interactome Map using Cytoscape software, we identified a single scale-free network consisting of 2630 interacting proteins and containing 449 differentially expressed proteins. We identified 27 hub proteins in the interactome with more than 29 edges incident on them and encoded by differentially expressed genes. The Gene Ontology analysis showed an excess of up-regulated proteins involved in biological processes, such as "morphogenesis", "cell fate determination" and "regulation of development", and the most up-regulated genes belonged to these categories. In addition, 267 genes were mapped to the KEGG pathways and 14 pathways with more than nine differentially expressed genes were identified. In our model, Smad signaling was not the TGF beta 1 action effector; instead, the engagement of RAS/MAPK signaling pathway seems mainly to regulate genes involved in the cell cycle and proliferation/apoptosis.ConclusionOur present findings support the hypothesis that context-dependent EMT generated in our model by TGF beta 1 might be the outcome of a dedifferentiation. In fact: 1) the principal biological categories involved in the process concern morphogenesis and development; 2) the most up-regulated genes belong to these categories; and, finally, 3) some intracellular pathways are involved, whose engagement during kidney development and nephrogenesis is well known. These long-term effects of TGF beta 1 in HUTEC involve genes that are highly interconnected, thereby generating a scale-free network that we named the "TGF beta 1 interactome", whose hubs represent proteins that may have a crucial role for HUTEC in response to TGF beta 1.

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Salvianolic acid B prevents epithelial-to-mesenchymal transition through the TGF-beta1 signal transduction pathway in vivo and in vitro.

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Salvianolic acid B prevents epithelial-to-mesenchymal transition through the TGF-beta1 signal transduction pathway in vivo and in vitro.

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