TGF-{beta}-induced MiR-491-5p expression promotes Par-3 degradation in rat proximal tubular epithelial cells

Par-3 is a component of Par complex, which is critical for the integrity of tight junction. We previously reported that TGF-β down-regulated Par-3 expression in rat proximal tubular epithelial cells, but the underlying mechanism remains unknown. In the present study, we demonstrated by a luciferase reporter assay that miR-491-5p down-regulated the luciferase activity through a binding site in the 3' UTR of Par-3. Overexpression of miR-491-5p dramatically decreased the expression of endogenous Par-3, disrupted tight junction, and resulted in decreased transepithelial resistance. Moreover, miR-491-5p expression was induced by TGF-β1 through the MEK/p38 MAPK pathway. Importantly, miR-491-5p levels were increased significantly in a rat model of obstructive nephropathy, in parallel with decreased Par-3 levels. Taken together, we conclude that up-regulation of miR-491-5p contributes to TGF-β-regulated Par-3 expression. Our study uncovered a novel mechanism by which TGF-β disrupts cell junction.     

TGF-β1-induced epithelial–mesenchymal transition in lung cancer cells involves upregulation of miR-9 and downregulation of its target,E-cadherin

Background

TGF-β1 plays an important role in the epithelial–mesenchymal transition (EMT) of epithelial cancers, including non-small cell lung cancer (NSCLC). While the full underlying mechanism remains unclear, miR-9 is known to play a critical role in the regulation of NSCLC cell invasion. We tested whether miR-9 targets E-cadherin and thus affects TGF-β1-induced EMT in NSCLC cells by assessing the expression levels of miR-9 and E-cadherin for NSCLC patients and then verifying the targeting of E-cadherin by miR-9 using the dual luciferase reporter system.

Results

MiR-9 was significantly upregulated in NSCLC tissues compared with its level in adjacent normal tissues. The expression of E-cadherin in NSCLC tissues was significantly decreased. In addition, we found that TGF-β1 significantly upregulated the expression of miR-9 and downregulated the expression of E-cadherin. E-cadherin was confirmed as a direct target gene of miR-9. Using an miR-9 inhibitor reversed the TGF-β1-mediated inhibition of E-cadherin expression and upregulation of the mesenchymal marker α-SMA. TGF-β1 significantly induced cell invasion, and this effect was significantly inhibited by miR-9 inhibitors.

Conclusions

TGF-β1 induced EMT in NSCLC cells by upregulating miR-9 and downregulating miR-9’s target, E-cadherin.

     

LncRNA lnc-ISG20 promotes renal fibrosis in diabetic nephropathy by inducing AKT phosphorylation through miR-486-5p/NFAT5

Long non-coding RNA (lncRNA) lnc-ISG20 has been found aberrantly up-regulated in the glomerular in the patients with diabetic nephropathy (DN). We aimed to elucidate the function and regulatory mechanism of lncRNA lnc-ISG20 on DN-induced renal fibrosis. Expression patterns of lnc-ISG20 in kidney tissues of DN patients were determined by RT-qPCR. Mouse models of DN were constructed, while MCs were cultured under normal glucose (NG)/high glucose (HG) conditions. The expression patterns of fibrosis marker proteins collagen IV, fibronectin and TGF-β1 were measured with Western blot assay. In addition, the relationship among lnc-ISG20, miR-486-5p, NFAT5 and AKT were analysed using dual-luciferase reporter assay and RNA immunoprecipitation. The effect of lnc-ISG20 and miR-486/NFAT5/p-AKT axis on DN-associated renal fibrosis was also verified by means of rescue experiments. The expression levels of lnc-ISG20 were increased in DN patients, DN mouse kidney tissues and HG-treated MCs. Lnc-ISG20 silencing alleviated HG-induced fibrosis in MCs and delayed renal fibrosis in DN mice. Mechanistically, miR-486-5p was found to be a downstream miRNA of lnc-ISG20, while miR-486-5p inhibited the expression of NFAT5 by binding to its 3'UTR. NFAT5 overexpression aggravated HG-induced fibrosis by stimulating AKT phosphorylation. However, NFAT5 silencing reversed the promotion of in vitro and in vivo fibrosis caused by lnc-ISG20 overexpression. Our collective findings indicate that lnc-ISG20 promotes the renal fibrosis process in DN by activating AKT through the miR-486-5p/NFAT5 axis. High-expression levels of lnc-ISG20 may be a useful indicator for DN.     

MicroRNA-155 targets SMAD2 and modulates the response of macrophages to transforming growth factor-{beta}

Transforming growth factor-beta (TGF-β) is a pleiotropic cytokine with important effects on processes such as fibrosis, angiogenesis, and immunosupression. Using bioinformatics, we identified SMAD2, one of the mediators of TGF-β signaling, as a predicted target for a microRNA, microRNA-155 (miR-155). MicroRNAs are a class of small non-coding RNAs that have emerged as an important class of gene expression regulators. miR-155 has been found to be involved in the regulation of the immune response in myeloid cells. Here, we provide direct evidence of binding of miR-155 to a predicted binding site and the ability of miR-155 to repress SMAD2 protein expression. We employed a lentivirally transduced monocyte cell line (THP1-155) containing an inducible miR-155 transgene to show that endogenous levels of SMAD2 protein were decreased after sustained overexpression of miR-155. This decrease in SMAD2 led to a reduction in both TGF-β-induced SMAD-2 phosphorylation and SMAD-2-dependent activation of the expression of the CAGA(12)LUC reporter plasmid. Overexpression of miR-155 altered the cellular responses to TGF-β by changing the expression of a set of genes that is involved in inflammation, fibrosis, and angiogenesis. Our study provides firm evidence of a role for miR-155 in directly repressing SMAD2 expression, and our results demonstrate the relevance of one of the two predicted target sites in SMAD2 3'-UTR. Altogether, our data uncover an important role for miR-155 in modulating the cellular response to TGF-β with possible implications in several human diseases where homeostasis of TGF-β might be altered.     

Retracted: microRNA-539 functions as a tumor suppressor in papillary thyroid carcinoma via the transforming growth factor β1/Smads signaling pathway by targeting secretory leukocyte protease inhibitor

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy, with growing incidence every year. microRNAs (miRs) are known to regulate the physiological and pathological processes of cancers, such as proliferation, migration, invasion, survival, and epithelial-mesenchymal transition (EMT). Herein, this study aimed to investigate the effect of miR-539 on cell proliferation, apoptosis, and EMT by targeting secretory leukocyte protease inhibitor (SLPI) via the transforming growth factor β1 (TGF-β1)/Smads signaling pathway in PTC. First, PTC-related differentially expressed genes and regulatory miR were screened using bioinformatics analysis, dual luciferase reporter gene assay, and ribonucleoprotein immunoprecipitation, which identified the SLPI gene and the regulatory miR-539 for this study. We identified SLPI as a highly expressed gene in PTC tissues, and SLPI was targeted and negatively regulated by miR-539. Then, we introduced a series of miR-539 mimics, miR-539 inhibitors, and small interfering RNA against SLPI plasmids into CGTHW-3 cells to examine the effects of miR-539 and SLPI on the expression of TGF-β1/Smads signaling pathway-, EMT-, and apoptosis-related factors, as well as cell proliferation, migration, invasion, and apoptosis. The obtained results indicated that CGTHW-3 cells treated with silenced SLPI or overexpressed miR-539 suppressed the cell proliferation, migration, invasion abilities, and resistance to apoptosis of PTC cells, corresponding to increased expression of Bcl-2-associated X protein, TGF-β1, Sekelsky mothers against dpp 4, and epithelial cadherin, and decreased B cell lymphoma 2, Vimentin, and N-cadherin. Altogether, we concluded that overexpressed miR-539 could inhibit the PTC cell proliferation and promote apoptosis and EMT by targeting SPLI via activation of the TGF-β1/Smads signaling pathway.