p38MAPK 信号通路在高糖诱导的人肾小管上皮细胞上皮-间质转化中的作用。
The role of the p38 MAPK signaling pathway in high glucose-induced epithelial-mesenchymal transition of cultured human renal tubular epithelial cells.
机构信息
Department of Nephrology, Provincial Hospital Affliated to Shandong University, JiNan, China.
出版信息
PLoS One. 2011;6(7):e22806. doi: 10.1371/journal.pone.0022806. Epub 2011 Jul 29.
BACKGROUND
Epithelial-mesenchymal transition of tubular epithelial cells, which is characterized by a loss of epithelial cell characteristics and a gain of ECM-producing myofibroblast characteristics, is an essential mechanism that is involved in tubulointerstitial fibrosis, an important component of the renal injury that is associated with diabetic nephropathy. Under diabetic conditions, p38 MAPK activation has been reported in glomeruli and mesangial cells; however, studies on p38 MAPK in TECs are lacking. In this study, the role of p38 MAPK in AP-1 activation and in the EMT in the human proximal tubular epithelial cell line (HK-2) under high glucose concentration conditions is investigated.
METHODOLOGY/PRINCIPAL FINDINGS: A vector for small interfering RNA that targets p38 MAPK was constructed; the cells were then either transfected with p38 siRNA or pretreated with a chemical inhibitor of AP-1 and incubated with low glucose plus TGF-β1 or high glucose for 48 h. Cells that were not transfected or pretreated and were exposed to low glucose with or without TGF-β1 or high glucose for 48 h were considered to be the controls. We found that high glucose induced an increase in TGF-β1. And high glucose-induced p38 MAPK activation was inhibited by p38 siRNA (P<0.05). A significant decline in E-cadherin and CK expression and a notable increase in vimentin and α-SMA were detected when exposed to low glucose with TGF-β1 or high glucose, and a significant raise of secreted fibronectin were detected when exposed to high glucose; whereas these changes were reversed when the cells were treated with p38 siRNA or AP-1 inhibitor (P<0.05). AP-1 activity levels and Snail expression were up-regulated under high glucose conditions but were markedly down-regulated through knockdown of p38 MAPK with p38 siRNA or pretreatment with AP-1 inhibitor (P<0.05).
CONCLUSION
This study suggests that p38 MAPK may play an important role in the high glucose-induced EMT by activating AP-1 in tubular epithelial cells.
背景
管状上皮细胞的上皮-间充质转化（EMT），其特征是丧失上皮细胞特征和获得 ECM 产生的肌成纤维细胞特征，是肾小管间质纤维化的重要机制，是与糖尿病肾病相关的肾损伤的重要组成部分。在糖尿病条件下，已报道肾小球和系膜细胞中 p38 MAPK 的激活；然而，关于高糖浓度条件下 TEC 中 p38 MAPK 的研究尚缺乏。在这项研究中，研究了 p38 MAPK 在高糖浓度条件下人近端肾小管上皮细胞系（HK-2）中 AP-1 激活和 EMT 中的作用。
方法/主要发现：构建了靶向 p38 MAPK 的小干扰 RNA 载体；然后将细胞转染 p38 siRNA 或用 AP-1 的化学抑制剂预处理，并在低糖加 TGF-β1 或高糖下孵育 48 小时。未转染或预处理并在低糖加或不加 TGF-β1 或高糖下孵育 48 小时的细胞被认为是对照。我们发现高糖诱导 TGF-β1 增加。p38 siRNA 抑制高糖诱导的 p38 MAPK 激活（P<0.05）。在低糖加 TGF-β1 或高糖下，E-钙粘蛋白和 CK 表达显著下降，波形蛋白和 α-SMA 明显增加，高糖下分泌型纤连蛋白显著增加；而用 p38 siRNA 或 AP-1 抑制剂处理时，这些变化得到逆转（P<0.05）。AP-1 活性水平和 Snail 表达在高糖条件下上调，但通过 p38 MAPK 的 p38 siRNA 敲低或 AP-1 抑制剂预处理明显下调（P<0.05）。
结论
本研究表明，p38 MAPK 通过激活管状上皮细胞中的 AP-1，在高糖诱导的 EMT 中可能发挥重要作用。
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