Zhang Aiqing, Wang Bin, Yang Min, Shi Huimin, Gan Weihua
Department of Pediatric Nephrology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, P. R. China.
Division of Nephrology, Huashan Hospital and Institute of Nephrology, Fudan University, Shanghai, 200040, P.R. China.
BMC Nephrol. 2015 Apr 23;16:60. doi: 10.1186/s12882-015-0057-x.
The objective of this study was to investigate the influence of β2-microglobulin (β2-M) on the epithelial-mesenchymal transition (EMT) in renal tubular epithelial cells.
A human kidney proximal tubular cell line (HK-2) was used as the proximal tubular cell model. HK-2 cells were exposed to different concentrations of β2-M (5, 10, 25, and 50 μM) for up to 24, 48 and 72 h. The effects of β2-M on cell morphology were observed by phase contrast microscopy, and the possible associated mechanisms were assessed by immunofluorescence staining, western blot, RNA interference, immunoprecipitation, and induced coupled plasma mass spectroscopy.
β2-M induced marked morphological alterations in the HK-2 cells, accompanied by the increased expression of extracellular matrix components and α-smooth muscle actin (α-SMA), vimentin and fibronectin and the reduced expression of E-cadherin. Our results also revealed that β2-M could induce the EMT in the HK-2 cells without significant affecting cell viability. Excess β2-M in the HK-2 cells led to a decrease in iron and an increase in hypoxia inducible factor-1α (HIF-1α), which induced EMT in the HK-2 cells. Additionally, disrupting the function of the β2-M/hemochromatosis (HFE) complex by HFE knockdown was sufficient to reverse β2-M-mediated EMT in the HK-2 cells.
These findings demonstrate that the activity of β2-M is mediated by the β2-M/HFE complex, which regulates intracellular iron homeostasis and HIF-1α and ultimately induces EMT in HK2 cells.
本研究的目的是探讨β2-微球蛋白（β2-M）对肾小管上皮细胞上皮-间质转化（EMT）的影响。
使用人肾近端小管细胞系（HK-2）作为近端小管细胞模型。将HK-2细胞暴露于不同浓度的β2-M（5、10、25和50μM）中长达24、48和72小时。通过相差显微镜观察β2-M对细胞形态的影响，并通过免疫荧光染色、蛋白质印迹、RNA干扰、免疫沉淀和电感耦合等离子体质谱评估可能的相关机制。
β2-M诱导HK-2细胞出现明显的形态学改变，同时细胞外基质成分、α-平滑肌肌动蛋白（α-SMA）、波形蛋白和纤连蛋白的表达增加，而E-钙黏蛋白的表达降低。我们的结果还表明，β2-M可诱导HK-2细胞发生EMT，而对细胞活力无明显影响。HK-2细胞中过量的β2-M导致铁含量降低，缺氧诱导因子-（HIF-1α）增加，从而诱导HK-2细胞发生EMT。此外，通过敲低HFE破坏β2-M/血色素沉着症（HFE）复合物的功能足以逆转β2-M介导的HK-2细胞EMT。
这些发现表明，β2-M的活性由β2-M/HFE复合物介导，该复合物调节细胞内铁稳态和HIF-1α，最终诱导HK2细胞发生EMT。
