Metformin inhibits extracellular matrix accumulation, inflammation and proliferation of mesangial cells in diabetic nephropathy by regulating H19/miR-143-3p/TGF-β1 axis.

Metformin (MET) has protective effect on diabetic nephropathy (DN). This study aims to demystify the mechanism of MET function in DN. Mouse glomerular membrane epithelial cell line SV40-MES-13 was treated with normal or high glucose combined with or without MET. The relationships among H19, miR-143-3p and TGF-β1 were evaluated by luciferase reporter assay. MTT assay was performed to detect cell proliferation. The levels of inflammatory factors were investigated by enzyme-linked immunosorbent assay. Quantitative real-time PCR and western blot were performed to examine gene and protein expression. H19 was up-regulated in the SV40-MES-13 cells after treated with high glucose, which was effectively repressed by MET treatment. MET promoted extracellular matrix accumulation, inflammation and proliferation in the SV40-MES-13 cells after treated with high glucose. These influences conferred by MET were abolished by H19 overexpression. H19 regulated TGF-β1 expression by sponging miR-143-3p. Furthermore, MET inhibited extracellular matrix accumulation, inflammation and proliferation by regulating H19/miR-143-3p/TGF-β1 axis. Our studies demonstrated that the protective effect of MET on DN was attributed to the inhibition of proliferation, inflammation and ECM accumulation in mesangial cells via H19/miR-143-3p/TGF-β1 axis, which suggested that the H19/miR-143-3p/TGF-β1 axis could be a valuable target for DN therapies.

Xu J ，Xiang P ，Liu L ，Sun J ，Ye S ... -  《-》

Circular RNA circRNA_15698 aggravates the extracellular matrix of diabetic nephropathy mesangial cells via miR-185/TGF-β1.

Circular RNAs (circRNAs) are a novel type of noncoding RNAs that modulate the pathogenesis of multiple diseases. Nevertheless, the role of circRNAs in diabetic nephropathy (DN) pathogenesis is still ambiguous. In the current study, our team aims to investigate the expression profiles of circRNAs in DN and identify the function of circRNA on mesangial cells. CircRNAs microarray analysis revealed dysregulated circRNA in db/db DN mice, and circRNA_15698 was validated to be upregulated in both db/db mice and mouse mesangial cells (SV40-MES13) that were exposed to high glucose (25 mM) using real-time polymerase chain reaction. Loss-of-functional experiments showed that circRNA_15698 knockdown significantly inhibited the expression levels of collagen type I (Col. I), collagen type IV (Col. IV), and fibronectin. Moreover, the cellular localization of circRNA_15698 was mainly in the cytoplasm. Bioinformatics tools and luciferase reporter assay confirmed that circRNA_15698 acted as a 'sponge' of miR-185, and then positively regulated the transforming growth factor-β1 (TGF-β1) protein expression, suggesting a circRNA_15698/miR-185/TGF-β1 pathway. Further validation experiments validated that circRNA_15698/miR-185/TGF-β1 promoted extracellular matrix (ECM)-related protein synthesis. In summary, our study preliminarily investigates the role of circRNAs in mesangial cells and ECM accumulation, providing a novel insight for DN pathogenesis.

Hu W ，Han Q ，Zhao L ，Wang L ... -  《-》

Circ-AKT3 inhibits the accumulation of extracellular matrix of mesangial cells in diabetic nephropathy via modulating miR-296-3p/E-cadherin signals.

Diabetic nephropathy is a leading cause of end-stage renal disease globally. The vital role of circular RNAs (circRNAs) has been reported in diabetic nephropathy progression, but the molecular mechanism linking diabetic nephropathy to circRNAs remains elusive. In this study, we investigated the significant function of circ-AKT3/miR-296-3p/E-cadherin regulatory network on the extracellular matrix accumulation in mesangial cells in diabetic nephropathy. The expression of circ-AKT3 and fibrosis-associated proteins, including fibronectin, collagen type I and collagen type IV, was assessed via RT-PCR and Western blot analysis in diabetic nephropathy animal model and mouse mesangial SV40-MES13 cells. Luciferase reporter assays were used to investigate interactions among E-cadherin, circ-AKT3 and miR-296-3p in mouse mesangial SV40-MES13 cells. Cell apoptosis was evaluated via flow cytometry. The level of circ-AKT3 was significantly lower in diabetic nephropathy mice model group and mouse mesangial SV40-MES13 cells treated with high-concentration (25 mmol/L) glucose. In addition, circ-AKT3 overexpression inhibited the level of fibrosis-associated protein, such as fibronectin, collagen type I and collagen type IV. Circ-AKT3 overexpression also inhibited the apoptosis of mouse mesangial SV40-MES13 cells treated with high glucose. Luciferase reporter assay and bioinformatics tools identified that circ-AKT3 could act as a sponge of miR-296-3p and E-cadherin was the miR-296-3p direct target. Moreover, circ-AKT3/miR-296-3p/E-cadherin modulated the extracellular matrix of mouse mesangial cells in high-concentration (25 mmol/L) glucose, inhibiting the synthesis of related extracellular matrix protein. In conclusion, circ-AKT3 inhibited the extracellular matrix accumulation in diabetic nephropathy mesangial cells through modulating miR-296-3p/E-cadherin signals, which might offer novel potential opportunities for clinical diagnosis targets and therapeutic biomarkers for diabetic nephropathy.

Tang B ，Li W ，Ji TT ，Li XY ，Qu X ，Feng L ，Bai S ... -  《-》

Knockdown of plasmacytoma variant translocation 1 (PVT1) inhibits high glucose-induced proliferation and renal fibrosis in HRMCs by regulating miR-23b-3p/early growth response factor 1 (EGR1).

Yu D ，Yang X ，Zhu Y ，Xu F ，Zhang H ，Qiu Z ... -  《-》

Long noncoding RNA TUG1 alleviates extracellular matrix accumulation via mediating microRNA-377 targeting of PPARγ in diabetic nephropathy.

Long noncoding RNA taurine-upregulated gene 1 (lncRNA TUG1) has been reported to play a key role in the progression of diabetic nephropathy (DN). However, the role of lncRNA TUG1 in the regulation of diabetic nephropathy remains largely unknown. The aim of the present study is to identify the regulation of lncRNA TUG1 on extracellular matrix accumulation via mediating microRNA-377 targeting of PPARγ, and investigate the underlying mechanisms in progression of DN. Microarray was performed to screen differentially expressed miRNAs in db/db DN mice. Afterwards, computational prediction programs (TargetScan, miRanda, PicTar and miRGen) was applied to predict the target gene of miRNAs. The complementary binding of miRNA and lncRNA was assessed by luciferase assays. Protein and mRNA expression were detected by western blot and real time quantitate PCR. MiRNA-377 was screened by miRNA microarray and differentially up-regulated in db/db DN mice. PPARγ was predicted to be the target of miR-377 and the prediction was verified by luciferase assays. Expression of miR-377 was up-regulated in mesangial cell treated with high glucose (25 mM), and overexpression of miR-377 inhibited PPARγ expression and promoted PAI-1 and TGF-β1 expression. The expression of TUG1 antagonized the effect of miR-377 on the downregulation of its target PPARγ and inhibited extracellular matrix accumulation, including PAI-1, TGF-β1, fibronectin (FN) and collagen IV (Col IV), induced by high glucose. LncRNA TUG1 acts as an endogenous sponge of miR-377 and downregulates miR-377 expression levels, and thereby relieving the inhibition of its target gene PPARγ and alleviates extracellular matrix accumulation of mesangial cells, which provides a novel insight of diabetic nephropathy pathogenesis.

Duan LJ ，Ding M ，Hou LJ ，Cui YT ，Li CJ ，Yu DM ... -  《-》