Let-7d miRNA prevents TGF-β1-induced EMT and renal fibrogenesis through regulation of HMGA2 expression.

TGF-β1-induced epithelial to mesenchymal transition (EMT) process of tubular epithelial cells plays a leading role in the occurrence and progression of renal fibrosis as seen in diabetic nephropathy (DN). High mobility group AT-hook 2 (HMGA2) is considered to be involved in TGF-β1-mediated EMT via multifactorial mechanisms. Specific microRNAs (miRNAs) are closely associated with EMT, and here we focused on let-7d miRNA as a regulator of HMGA2. This study aims to investigate the effects of HMGA2 on EMT process induced by TGF-β1 using small interfering RNA (siRNA) technique in vitro, and further explore the potential role of let-7d miRNA during renal fibrosis in DN. We demonstrated that siRNA targeting HMGA2 was sufficient to inhibit TGF-β1-induced EMT and fibrogenesis in rat kidney tubular epithelial cells (NRK52E). Furthermore, let-7d expression was significantly reduced by TGF-β1 stimulation, we focused on let-7d and found that overexpression of let-7d down-regulated the expression of HMGA2 and in turn suppressed TGF-β1-induced EMT and renal fibrogenesis. Inhibition of let-7d increased HMGA2 expression and enhanced the profibrogenic effects of TGF-β1 on NRK-52E cells. Consistent with the above observations in vitro, let-7d expression was also decreased in the kidneys of unilateral ureter obstruction model, accompanied by the correspondingly increased expression of HMGA2 and fibrotic genes in this model. Collectively, HMGA2 and let-7d miRNA significantly impact on the progression of TGF-β1-induced EMT and fibrogenesis both in vitro and in vivo, and they may represent novel targets for the prevention strategies of renal fibrosis in the context of DN.

Wang Y ，Le Y ，Xue JY ，Zheng ZJ ，Xue YM ... -  《-》

Up-regulation of microRNA-93 inhibits TGF-β1-induced EMT and renal fibrogenesis by down-regulation of Orai1.

TGF-β1-induced excessive deposition of ECM and EMT process of tubular epithelial cells play critical roles in the development and progression of fibrosis in diabetic nephropathy (DN). Orai1 has been demonstrated to be involved in TGF-β1-induced EMT via TGF-β/Smad3 pathway. We are aimed to explore the effects of miR-93 on TGF-β1-induced EMT process in HK2 cells. In this study, our data showed that miR-93 was dramatically decreased in renal tissues of patients with DN and TGF-β1-stimulated HK2 cells. Moreover, the decreased level of miR-93 was closely associated with the increased expression of Orai1. Overexpression of miR-93 decreased Orai1 expression, and then suppressed TGF-β1-mediated EMT and fibrogenesis. Next, we predicted that the Orai1 was a potential target gene of miR-93, and demonstrated that miR-93 could directly target Orai1. SiRNA targeting Orai1 was sufficient to suppress TGF-β1-induced EMT and fibrogenesis in HK2 cells. Furthermore, Overexpression of Orai1 partially reversed the protective effect of miR-93 overexpression on TGF-β1-mediated EMT and fibrogenesis in HK2 cells. Taken together, Orai1 and miR-93 significantly impact on the progression of TGF-β1-mediated EMT and fibrogenesis in HK2 cells, and they may represent novel targets for the prevention strategies of fibrosis in the context of DN.

Ma J ，Zhang L ，Hao J ，Li N ，Tang J ，Hao L ... -  《-》

Effects and mechanism of miR-23b on glucose-mediated epithelial-to-mesenchymal transition in diabetic nephropathy.

MicroRNAs (miRNAs) play important roles in epithelial-to-mesenchymal transition (EMT). Moreover, hyperglycaemia induces damage to renal tubular epithelial cells, which may lead to EMT in diabetic nephropathy. However, the effects of miRNAs on EMT in diabetic nephropathy are poorly understood. In the present study, we found that the level of microRNA-23b (miR-23b) was significantly decreased in high glucose (HG)-induced human kidney proximal tubular epithelial cells (HK2) and in kidney tissues of db/db mice. Overexpression of miR-23b attenuated HG-induced EMT, whereas knockdown of miR-23b induced normal glucose (NG)-mediated EMT in HK2 cells. Mechanistically, miR-23b suppressed EMT in diabetic nephropathy by targeting high mobility group A2 (HMGA2), thereby repressing PI3K-AKT signalling pathway activation. Additionally, HMGA2 knockdown or inhibition of the PI3K-AKT signalling pathway with LY294002 mimicked the effects of miR-23b overexpression on HG-mediated EMT, whereas HMGA2 overexpression or activation of the PI3K-AKT signalling pathway with BpV prevented the effects of miR-23b on HG-mediated EMT. We also confirmed that overexpression of miR-23b alleviated EMT, decreased the expression levels of EMT-related genes, ameliorated renal morphology, glycogen accumulation, fibrotic responses and improved renal functions in db/db mice. Taken together, we showed for the first time that miR-23b acts as a suppressor of EMT in diabetic nephropathy through repressing PI3K-AKT signalling pathway activation by targeting HMGA2, which maybe a potential therapeutic target for diabetes-induced renal dysfunction.

Liu H ，Wang X ，Liu S ，Li H ，Yuan X ，Feng B ，Bai H ，Zhao B ，Chu Y ，Li H ... -  《-》

Down-regulation of miR-23a inhibits high glucose-induced EMT and renal fibrogenesis by up-regulation of SnoN.

Xu H ，Sun F ，Li X ，Sun L ... -  《Human Cell》

miR-21 overexpression enhances TGF-β1-induced epithelial-to-mesenchymal transition by target smad7 and aggravates renal damage in diabetic nephropathy.

Epithelial-to-mesenchymal transition (EMT) plays an important role in renal interstitial fibrosis (RIF) with diabetic nephropathy (DN). Smad7 (a inhibitory smad), a downstream signaling molecules of TGF-β1, represses the EMT. The physiological function of miR-21 is closely linked to EMT and RIF. However, it remained unclear whether miR-21 over-expression affected TGF-β1-induced EMT by regulating smad7 in DN. In this study, real-time RT-PCR, cell transfection, luciferase reporter gene assays, western blot and confocal microscope were used, respectively. Here, we found that miR-21 expression was upregulated by TGF-β1 in time- and concentration -dependent manner. Moreover, miR-21 over-expression enhanced TGF-β1-induced EMT(upregulation of a-SMA and downregulation of E-cadherin) by directly down-regulating smad7/p-smad7 and indirectly up-regulating smad3/p-smad3, accompanied by the decrease of Ccr and the increase of col-IV, FN, the content of collagen fibers, RTBM, RTIAW and ACR. Meantime, the siRNA experiment showed that smad7 can directly regulate a-SMA and E-cadherin expression. More importantly, miR-21 inhibitor can not only inhibit EMT and fibrosis but also ameliorate renal structure and function. In conclusion, our results demonstrated that miR-21 overexpression can contribute to TGF-β1-induced EMT by inhibiting target smad7, and that targeting miR-21 may be a better alternative to directly suppress TGF-β1-mediated fibrosis in DN.

Wang JY ，Gao YB ，Zhang N ，Zou DW ，Wang P ，Zhu ZY ，Li JY ，Zhou SN ，Wang SC ，Wang YY ，Yang JK ... -  《-》