MALAT1 Modulates TGF-β1-Induced Endothelial-to-Mesenchymal Transition through Downregulation of miR-145.

Endothelial-to-mesenchymal transition (EndMT) plays significant roles under various pathological conditions including cardiovascular diseases, fibrosis, and cancer. EndMT of endothelial progenitor cells (EPCs) contributes to neointimal hyperplasia following cell therapy Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA (lncRNA) that promotes metastasis and cancer. MicroRNA-145 (miR-145) is a tumor suppressor that has been reported to inhibit SMAD3-mediated epithelial-to-mesenchymal transition (EMT) of cancer cells. In the present study, we investigated the role of MALAT1 and miR-145 in EndMT of human circulating EPCs induced by transforming growth factor beta1 (TGF-β1). Human circulating EPCs were isolated and characterized by fluorescence-activated cell sorting (FACS). Expression levels of EndMT markers were assessed by qRT-PCR and western blotting. Alpha-smooth muscle actin (α-SMA) expression was measured by cell immunofluorescence staining. The regulatory relationship between MALAT1 and miR-145 and its target genes, TGFBR2 (TGFβ receptortype II) and SMAD3 (mothers against decapentaplegic homolog 3) was analyzed using the luciferase reporter assay. We found that EndMT of EPCs induced by TGF-β1 is accompanied by increased MALAT1 expression and decreased miR-145 expression, and MALAT1 and miR-145 directly bind and reciprocally repress each other in these cells. Dual-Luciferase Reporter assay indicated that miR-145 inhibits TGF-β1-induced EndMT by directly targeting TGFBR2 and SMAD3. MALAT1 modulates TGF-β1-induced EndMT of EPCs through regulation of TGFBR2 and SMAD3 via miR-145. Thus, the MALAT1-miR-145-TGFBR2/SMAD3 signaling pathway plays a key role in TGF-β1-induced EndMT.

Xiang Y ，Zhang Y ，Tang Y ，Li Q ... -  《-》

Epigenetically-Regulated MicroRNA-9-5p Suppresses the Activation of Hepatic Stellate Cells via TGFBR1 and TGFBR2.

Recently, microRNAs (miRNAs) have been demonstrated to act as regulators of activation of hepatic stellate cells (HSCs). It is well known that the main profibrogenic inducer transforming growth factor-β1 (TGF-β1) contributes to HSC activation, which is a key event in liver fibrosis. Increasing studies show that miR-9-5p is down-regulated in liver fibrosis and restoration of miR-9-5p limits HSC activation. However, the role of miR-9-5p in TGF-β1-induced HSC activation is still not clear. miR-9-5p expression was quantified using real-time PCR in chronic hepatitis B (CHB) patients and TGF-β1-treated LX-2 cells. In CHB patients, histological activity index (HAI) and fibrosis stages were assessed using the Ishak scoring system. Effects of miR-9-5p on liver fibrosis in vivo and in vitro were analyzed. Luciferase activity assays were performed to examine the binding of miR-9-5p to the 3'-untranslated region of type I TGF-β receptor (TGFBR1) as well as TGFBR2. Compared with healthy controls, miR-9-5p was reduced in CHB patients. There was a lower miR-9-5p expression in CHB patients with higher fibrosis scores or HAI scores. miR-9-5p was down-regulated by TGF-β1 in a dose-dependent manner. TGF-β1-induced HSC activation including cell proliferation, α-SMA and collagen expression was blocked down by miR-9-5p. Notably, miR-9-5p ameliorates carbon tetrachloride-induced liver fibrosis. As determined by luciferase activity assays, TGFBR1 and TGFBR2 were targets of miR-9-5p. Further studies demonstrated that miR-9-5p inhibited TGF-β1/Smads pathway via TGFBR1 and TGFBR2. Interestingly, promoter methylation was responsible for miR-9-5p down-regulation in liver fibrosis. The relationship between miR-9-5p expression and methylation was confirmed in CHB patients and TGF-β1-treated cells. Our results demonstrate that miR-9-5p could inhibit TGF-β1-induced HSC activation through TGFBR1 and TGFBR2. Loss of miR-9-5p is associated with its methylation status in liver fibrosis.

Yu F ，Chen B ，Fan X ，Li G ，Dong P ，Zheng J ... -  《-》

Activated phosphatidylinositol 3-kinase/Akt inhibits the transition of endothelial progenitor cells to mesenchymal cells by regulating the forkhead box subgroup O-3a signaling.

Endothelial progenitor cells (EPCs) differentiate into mature endothelial cells and may thus be candidates for ischemic disease therapy; however, the transition of EPCs to mesenchymal cells is not fully understood. We explored the role of phosphatidylinositol 3-kinase (PI3K)/Akt signaling in endothelial-to-mesenchymal transition (EndMT) induced by transforming growth factor beta 1 (TGF-β1). Rat bone marrow-derived EPCs were isolated by using Ficoll-Isopaque Plus density-gradient centrifugation. EndMT was induced by TGF-β1 (5 ng/mL). PI3K/Akt signaling was activated by IGF-1 or Lenti-PIK3R2 shRNA. Additionally, FoxO3a expression was suppressed by a lentiviral vector (Lenti-FoxO3a shRNA). Smad3 and FoxO3a co-localization was detected by confocal immunofluorescence microscopy. The expressions of molecules involved in EndMT were exmined by using Western-blot analysis. EndMT of EPCs was fully developed after TGF-β1 treatment (5 ng/mL) for 7 days. PIK3R2 expression in EPCs was driven by TGF-β1. Lenti-PIK3R2 shRNA blocked alpha-smooth muscle actin (α-SMA) expression in EPCs treated with TGF-β1, drove PI3K/Akt activation, and increased expression of phosphorylated FoxO3a instead of phosphorylated Smad3. The effect of Lenti-PIK3R2 shRNA was reduced by LY294002, a specific inhibitor of PI3K. IGF-1 attenuated α-SMA protein expression in EPCs treated with TGF-β1. Similar to Lenti-PIK3R2 shRNA, IGF-1 also inhibited and elevated the phosphorylation of Smad3 and FoxO3a, respectively. IGF-1 disrupted the co-localization of these proteins in EPCs treated with TGF-β1. Lenti-FoxO3a shRNA transfection of EPCs suppressed expression of FoxO3a as well as that of the mesenchymal markers SM22α and α-SMA. Activation of PI3K/Akt signaling by Lenti-PIK3R2 shRNA or by exogenous IGF-1 inhibits EndMT in EPCs via negative regulation of FoxO3a-dependent signaling.

Zhang Z ，Zhang T ，Zhou Y ，Wei X ，Zhu J ，Zhang J ，Wang C ... -  《-》

Linc-ROR Modulates the Endothelial-Mesenchymal Transition of Endothelial Progenitor Cells through the miR-145/Smad3 Signaling Pathway.

Liang J ，Chu H ，Ran Y ，Lin R ，Cai Y ，Guan X ，Cui X ，Zhang X ，Li H ，Cheng M ... -  《-》

Long Non-Coding RNA MALAT1 Mediates Transforming Growth Factor Beta1-Induced Epithelial-Mesenchymal Transition of Retinal Pigment Epithelial Cells.

Yang S ，Yao H ，Li M ，Li H ，Wang F ... -  《PLoS One》