5595

MAPK3

Metastasis of tumor cells is associated with epithelial-to-mesenchymal transition (EMT), which is a process whereby epithelial cells lose their polarity and acquire new features of mesenchyme. EMT has been reported to be induced by transforming growth factor-beta1 (TGF-beta1), but its mechanism remains elusive. In this study, we performed a study to investigate whether PI3K/Akt and MAPK/Erk1/2 signaling pathways involved in EMT in the human lung cancer A549 cells. The results showed that after treated with TGF-beta1 for 48 h, A549 cells displayed more fibroblast-like shape, lost epithelial marker E-cadherin and increased mesenchymal markers Vimentin and Fibronectin. Moreover, TGF-beta1-induced EMT after 48 h was accompanied by increased of cell migration and change of Akt and Erk1/2 phosphorylation. In addition, EMT was reversed by PI3K inhibitor LY294002 and MEK1/2 inhibitor U0126, which suggested that A549 cells under stimulation of TGF-beta1 undergo a switch into mesenchymal cells and PI3K/Akt and MAPK/Erk1/2 signaling pathways serve to regulate TGF-beta1-induced EMT of A549 cells.

epithelial-mesenchymal transition (EMT) of retinal pigment epithelium (RPE) cells is a major pathologic change in the development of proliferative vitreoretinopathy (PVR), which leads to severe visual impairment. ERK1/2 pathway has been reported to play a key role in the carcinogenesis, cancer metastasis, and multiple fibrotic diseases. We hypothesized that ERK1/2 signaling could cross-interact with transforming growth factor beta2 (TGFbeta2)/Smad and Notch signaling pathways in the regulation of EMT in RPE cells. Here, we demonstrated that ERK1/2 signaling was activated in TGFbeta2-induced EMT in human RPE cells, while blockade of the canonical TGFbeta2/Smad2/3 signaling with SB431542 could not inhibit TGFbeta2-induced the activation of ERK1/2. Meanwhile, blockade of ERK1/2 signaling with a specific MEK/ERK1/2 inhibitor U0126 strongly prevented TGFbeta2-induced the downregulation of P-cadherin, and the upregulation of alpha-SMA, collagen type IV, N-cadherin and fibronectin in RPE cells. In addition, we also identified that blockade of ERK1/2 signaling could inhibit not only the canonical TGFbeta/Smad signaling, but also the Jagged/Notch pathway. Finally, we found that blockade of Notch pathway with a specific inhibitor DAPT could inhibit TGFbeta2-induced the activation of ERK1/2 pathway conversely. Therefore, our study provides evidence that ERK1/2 signaling can cross-interact with the canonical TGFbeta/Smad and the Jagged/Notch signaling pathways in RPE cells EMT. ERK1/2 inhibitor may have therapeutic value in the prevention and treatment of PVR and other fibrotic diseases.

MicroRNA-21 (miR-21) has emerged as a critical regulatory molecule and an important serum marker in hepatic fibrogenesis. The aim of the present study was to investigate the role of inhibiting miR-21 on hepatic fibrosis treatment. Serum miR-21 levels in 60 healthy individuals and 180 patients with different stages of liver cirrhosis were examined, miR-21 levels in normal or cirrhotic human liver tissues (n=10 each) were also detected. An adenoviral vector (Ad-TuD-21) carrying the sponging ToughDecoy (TuD)-RNA sequence against miR-21 was constructed to reduce miR-21 expression efficiently in vitro and in vivo Histological and immunohistological examinations were performed to evaluate the inhibitory effects and mechanism of Ad-TuD-21 delivery into carbon tetrachloride (CCl4) induced hepatic fibrosis rats by targeting extracellular signal-regulated kinase 1 (ERK1) signalling in hepatic stellate cells (HSC) and hepatocyte epithelial-mesenchymal transition (EMT). Our results revealed that enhanced miR-21 levels in cirrhotic patients were related to the severity and activity of liver cirrhosis. Ad-TuD-21 administered to liver fibrosis rats could remarkably suppress profibrotic gene expression, cause histological improvements in liver and attenuate hepatic fibrosis significantly. More importantly, after Ad-TuD-21 treatment, inhibition of both the ERK1 signalling pathway in HSC and hepatocyte EMT was confirmed, which paralleled the enhancement of miR-21 target genes-sprouty2 (SPRY2) and hepatocyte nuclear factor 4alpha (HNF4alpha)-expression in vivo These data demonstrated that miR-21 is a key regulator to promote hepatic fibrogenesis, and sponging miR-21 expression may present a novel potentially therapeutic option for hepatic fibrosis.CI - (c) 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

Endometriosis, characterized by extrauterine development of endometrial glands and stroma, is associated with increased risk of ovarian cancer development. In the present study, we investigated the role of matrix metalloproteinase-7 (MMP-7) on epithelial-mesenchymal transition (EMT) during ovarian endometriosis ( N = 40) progression. We found that the expressions of EMT markers such as vimentin, slug, and N-cadherin were significantly elevated in late stages of ovarian endometriosis compared with those found in early stages. In addition, the activity and expression of ectopic MMP-7 were significantly higher in the late stages of endometriosis. In vitro studies revealed that increased expression of MMP-7 as well as epidermal growth factor (EGF), which was significantly elevated in severe stages of ovarian endometriosis, induced EMT in endocervical epithelial cells (End1/E6E7). Silencing the MMP-7 transcripts using small interfering RNA attenuated EMT responses, whereas treatment with recombinant active MMP-7 promoted EMT by cleaving E-cadherin. In addition, EGF receptor (EGFR) inhibitor treatments regressed endometriotic lesions and decreased MMP-7 activities in a mouse model of endometriosis. Chromatin immunoprecipitation assay identified EGFR-mediated ERK1 and activator protein 1 signaling for the transcriptional activation of MMP-7 in End1/E6E7 epithelial cells.-Chatterjee, K., Jana, S., DasMahapatra, P., Swarnakar, S. EGFR-mediated matrix metalloproteinase-7 up-regulation promotes epithelial-mesenchymal transition via ERK1-AP1 axis during ovarian endometriosis progression.

epithelial-mesenchymal transition (EMT) is an important process that contributes to renal fibrogenesis. TGF-beta1 and EGF stimulate EMT. Recent studies suggested that parathyroid hormone-related protein (PTHrP) promotes fibrogenesis in the damaged kidney, apparently dependent on its interaction with vascular endothelial growth factor (VEGF), but whether it also interacts with TGF-beta and EGF to modulate EMT is unknown. Here, PTHrP(1-36) increased TGF-beta1 in cultured tubuloepithelial cells and TGF-beta blockade inhibited PTHrP-induced EMT-related changes, including upregulation of alpha-smooth muscle actin and integrin-linked kinase, nuclear translocation of Snail, and downregulation of E-cadherin and zonula occludens-1. PTHrP(1-36) also induced EGF receptor (EGFR) activation; inhibition of protein kinase C and metalloproteases abrogated this activation. Inhibition of EGFR activation abolished these EMT-related changes, the activation of ERK1/2, and upregulation of TGF-beta1 and VEGF by PTHrP(1-36). Moreover, inhibition of ERK1/2 blocked EMT induced by either PTHrP(1-36), TGF-beta1, EGF, or VEGF. In vivo, obstruction of mouse kidneys led to changes consistent with EMT and upregulation of TGF-beta1 mRNA, p-EGFR protein, and PTHrP. Taken together, these data suggest that PTHrP, TGF-beta, EGF, and VEGF might cooperate through activation of ERK1/2 to induce EMT in renal tubuloepithelial cells.

In the developing heart, the epicardium is a major source of progenitor cells that contribute to the formation of the coronary vessel system. These epicardial progenitors give rise to the different cellular components of the coronary vasculature by undergoing a number of morphological and physiological changes collectively known as epithelial to mesenchymal transformation (EMT). However, the specific signaling mechanisms that regulate epicardial EMT are yet to be delineated. In this study we investigated the role of TGFbeta2 and hyaluronan (HA) during epicardial EMT and how signals from these two molecules are integrated during this important process. Here we show that TGFbeta2 induces MEKK3 activation, which in turn promotes ERK1/2 and ERK5 phosphorylation. TGFbeta2 also increases Has2 expression and subsequent HA production. Nevertheless, inhibition of MEKK3 kinase activity, silencing of ERK5 or pharmacological disruption of ERK1/2 activation significantly abrogates this response. Thus, TGFbeta2 promotes Has2 expression and HA production through a MEKK3/ERK1/2/5-dependent cascade. Furthermore, TGFbeta2 is able to induce epicardial cell invasion and differentiation but not proliferation. However, inhibition of MEKK3-dependent pathways, degradation of HA by hyaluronidases or blockade of CD44, significantly impairs the biological response to TGFbeta2. Taken together, these findings demonstrate that TGFbeta2 activation of MEKK3/ERK1/2/5 signaling modulates Has2 expression and HA production leading to the induction of EMT events. This is an important and novel mechanism showing how TGFbeta2 and HA signals are integrated to regulate changes in epicardial cell behavior.CI - Published by Elsevier Inc.

epithelial-to-mesenchymal transition (EMT) plays a crucial role in the progression of renal interstitial fibrosis, which finally leads to renal failure. Erbin, a member of LAP family, is recently reported to inhibit Smads and ERK pathway which are two important types of intracellular signaling involved in TGF-beta1-induced EMT. However, the role of Erbin in the regulation of EMT and the underlying mechanisms remain to be fully understood. To that end, we aimed to evaluate the expression of Erbin in renal interstitial fibrosis and the potential role of Erbin in tubular EMT stimulated by TGF-beta1. In this study we demonstrated that the expression of Erbin was upregulated in the tubular epithelia of 5/6-nephrectomized rats. We also showed here that TGF-beta1 upregulated Erbin expression in NRK52E cells during their EMT phenotype acquisition. Importantly, elevated expression of Erbin inhibited ERK signaling and partial reversed EMT stimulated by TGF-beta1. In the mean time, reducing Erbin expression enhanced ERK phosphorylation, promoted the E-cadherin suppression, and induced alpha-SMA expression and fibronection secretion in response to TGF-beta1, which could be rescued if cells were treated with the inhibitor of MEK1/2 U0126. However, in the absence of TGF-beta1, Erbin failed to affect ERK activation and EMT process. These results suggest that Erbin is a negative feedback molecule induced by TGF-beta1 and inhibits TGF-beta1-induced EMT via ERK signaling pathway.

BACKGROUND & AIMS: epithelial-mesenchymal transition (EMT) process and extracellular signal-regulated kinase 1 (ERK1) signalling pathway play pivotal roles in hepatic stellate cell (HSC) activation, which is associated with the altered expression patterns of microRNAs (miRNAs). miR-155 is considered a typical multifunctional miRNA to regulate many biological processes. However, little attention has been given to the contributions of miR-155 to simultaneous regulation of EMT process and ERK1 pathway during HSC activation. METHODS: Differential expression of miR-155 was assessed in activated HSC, sera and liver tissues from cirrhotic patients. Whether miR-155 could directly interact with 3'-untranslated region (3'-UTR) of T cell factor 4 (TCF4) and angiotensin II receptor type 1 (AGTR1) respectively was detected by luciferase reporter assay. The effects of enhanced miR-155 on EMT process and ERK1 pathway, cell apoptosis in HSC activation were also evaluated. RESULTS: A significant decrease in miR-155 expression was observed in activated HSC, sera or liver tissues of cirrhotic patients. MiR-155 was found to simultaneously interact with 3'-UTR of TCF4 and AGTR1 mRNAs, which are known as important regulators associated with EMT and ERK1 pathway repectively. Inhibiting miR-155 expression could stimulate the EMT state and ERK1 pathway activity, thus contributing to HSC activation. Forced miR-155 expression markedly decreased the mesenchymal markers and phosphorylated ERK1 level, and enhanced E-cadherin expression, leading to the synchronous inhibitory effect on EMT and ERK1 pathway and inducing HSC apoptosis. CONCLUSIONS: Our results implicate that miR-155 plays an important role in regulating the pathological network involving EMT process and ERK1 pathway during HSC activation.CI - (c) 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Cyclin-dependent kinase 5 (CDK5) has been documented in podocyte injuries in diabetic nephropathy (DN), however its role in renal tubular epithelial cells has not been elucidated. We report here that CDK5 is detrimental and promotes tubulointerstitial fibrosis (TIF) via the extracellular signal-regulated kinase 1/2 (ERK1/2)/peroxisome proliferator-activated receptor gamma (PPRAgamma) pathway in DN. In high glucose cultured NRK52E cells, blocking CDK5 activity inhibited epithelial-to-mesenchymal transition (EMT) and fibrosis via ERK1/2/PPARgamma pathway. In diabetic rats, CDK5 inhibitor roscovitine decreased renal fibrosis and improved renal function as demonstrated by a decrease in levels of blood urine nitrogen (BUN), serum creatinine and beta2-microglobulin. Further studies revealed that improved renal fibrosis and function in diabetic rats were associated with inactivation of ERK1/2 and PPARgamma signaling pathways. In late staged DN patients, the upregulation of CDK5 and p35 activated phosphorylated ERK1/2 and PPARgamma, leading to decreased levels of E-cadherin but increased Vimentin and Collagen IV. Accordingly, renal fibrosis and function were worsened as revealed by decreased estimated glomerular filtration rate (eGFR) and increased serum BUN, creatinine, beta2-microglobulin, 24-hour proteinuria and urine albumin to creatinine ratio (UACR). These findings demonstrate a novel mechanism that CDK5 increases tubulointerstitial fibrosis by activating the ERK1/2/PPARgamma pathway and EMT in DN. CDK5 might have therapeutic potential in diabetic nephropathy.