Epithelial-to-mesenchymal transition (EMT) and injury of tubular cells play critical roles in the pathogenesis of diabetic nephropathy (DN). lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been shown to be involved in DN progression. However, whether MALAT1 induces EMT and injury in tubular cells is unclear. Here, we investigated the effects of MALAT1 on human proximal tubular cells (HK-2 cells) and the underlying mechanism. We performed qPCR to detect MALAT1, E-cadherin, α-smooth muscle actin (α-SMA), kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). Additionally, we conducted Western blot analyses to measure E-cadherin, α-SMA, cyclin D1, c-Myc, and β-catenin in HK-2 cells cultured with normal glucose and high glucose (HG) and in transfected cells or cells treated with LiCl and DKK-1. The β-catenin localization was observed using immunofluorescence, and the protein levels of NGAL and KIM-1 were evaluated by ELISA. We found that HG-upregulated MALAT1 decreased E-cadherin and increased α-SMA, KIM-1, NGAL, cyclin D1, c-Myc, and β-catenin in HK-2 cells. LiCl exposure increased the expression of α-SMA but decreased that of E-cadherin on the base of knocking down MALAT1, and decreased NGAL and KIM-1 expression. DKK-1 showed the opposite effects. Our results suggested that upregulated MALAT1 induced EMT in HG-treated HK-2 cells through activating the Wnt/β-catenin pathway. However, MALAT1-mediated injury in HK-2 cells was not mediated by activation of the Wnt/β-catenin pathway. Our results indicate that MALAT1 might serve as a novel therapeutic target for suppressing the progression of DN.

中文翻译：

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lncRNA MALAT1介导高糖诱导的HK-2细胞上皮向间充质转化和损伤。

上皮-间质转化（EMT）和肾小管细胞损伤在糖尿病性肾病（DN）的发病机理中起着关键作用。lncRNA转移相关的肺腺癌转录本1（MALAT1）已被证明与DN进程有关。但是，尚不清楚MALAT1是否诱导EMT和肾小管细胞的损伤。在这里，我们调查了MALAT1对人类近端肾小管细胞（HK-2细胞）的影响及其潜在机制。我们进行了qPCR，以检测MALAT1，E-钙粘着蛋白，α平滑肌肌动蛋白（α-SMA），肾损伤分子1（KIM-1）和中性粒细胞明胶酶相关的脂蛋白（NGAL）。此外，我们进行了蛋白质印迹分析以测量E-钙黏着蛋白，α-SMA，细胞周期蛋白D1，c-Myc，正常葡萄糖和高葡萄糖（HG）培养的HK-2细胞以及转染的细胞或用LiCl和DKK-1处理的细胞中的β-catenin和β-catenin。使用免疫荧光观察β-连环蛋白的定位，并通过ELISA评估NGAL和KIM-1的蛋白水平。我们发现HG上调的MALAT1降低了HK-2细胞中的E-钙黏着蛋白并增加了α-SMA，KIM-1，NGAL，cyclin D1，c-Myc和β-catenin。LiCl暴露在敲低MALAT1的基础上增加了α-SMA的表达，但降低了E-cadherin的表达，并降低了NGAL和KIM-1的表达。DKK-1显示相反的效果。我们的结果表明，通过激活Wnt /β-catenin途径，上调MALAT1诱导HG处理的HK-2细胞中的EMT。然而，HK-2细胞中MALAT1介导的损伤不是由Wnt /β-catenin途径的激活介导的。