Background. Although the deposition of extracellular matrix (ECM) is critical leading to tubular damage in diabetic kidney disease (DKD), the mechanism still remains unclear. The purpose of this study was to demonstrate a role for protein kinase R-like endoplasmic reticulum kinase (PERK) (a protein located in the endoplasmic reticulum membrane) in this pathologic process. Methods. NRK-52E cells were grown in the media containing different concentrations of glucose or thapsigargin for different durations. Cells were subsequently incubated with or without AG490, a selective inhibitor of Janus kinase 2 (JAK2) or GSK2606414 (a selective PERK inhibitor). We evaluated the production of TGF-β1, fibronectin, and collagen I proteins by ELISA. The levels of 78 kD-glucose-regulated protein (GRP78) and PERK, as well as the phosphorylation statues of PERK and JAK2/signal transducer and activator of transcription (STAT3), were determined by western blotting analysis. Results. We showed that the increased phosphorylation of JAK2 and STAT3 was accompanied by overexpression of TGF-β1 and ECM deposition in high glucose medium. Disruption of the JAK2/STAT3 pathway with AG490 significantly prevents the high glucose-induced increase in TGF-β1, fibronectin, and collagen I. High glucose induced the overproduction of GRP78 and phosphorylation of PERK, which indicated that endoplasmic reticulum stress (ERS) was triggered in NRK-52E cells cultured under high glucose condition. Inhibition of PERK phosphorylation with GSK2606414, however, blocked the effect of JAK2/STAT3 on the production of TGF-β1 and ECM components in NRK-52E cells. Conclusion. Our data indicated that the ECM accumulation induced by high glucose arouse via the PERK-dependent JAK2/STAT3-signaling pathway in renal tubular epithelial cells.

中文翻译：

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JAK2/STAT3 通路的 PERK 依赖性激活有助于肾小管上皮细胞中高葡萄糖诱导的细胞外基质沉积

背景。尽管细胞外基质 (ECM) 的沉积是导致糖尿病肾病 (DKD) 肾小管损伤的关键，但其机制仍不清楚。本研究的目的是证明蛋白激酶 R 样内质网激酶 (PERK)（一种位于内质网膜中的蛋白质）在这一病理过程中的作用。方法。NRK-52E 细胞在含有不同浓度葡萄糖或毒胡萝卜素的培养基中生长不同持续时间。随后将细胞与或不与 AG490、Janus 激酶 2 (JAK2) 的选择性抑制剂或 GSK2606414（选择性 PERK 抑制剂）一起孵育。我们评估了 TGF- β的产生1、纤连蛋白和I型胶原蛋白通过ELISA检测。通过蛋白质印迹分析确定 78 kD-葡萄糖调节蛋白 (GRP78) 和 PERK 的水平，以及 PERK 和 JAK2/信号转导和转录激活因子 (STAT3) 的磷酸化状态。结果。我们发现 JAK2 和 STAT3 的磷酸化增加伴随着 TGF- β1的过表达和 ECM 在高葡萄糖培养基中的沉积。用 AG490 破坏 JAK2/STAT3 通路可显着防止高糖诱导的 TGF- β增加1、纤连蛋白和I型胶原蛋白。高糖诱导了GRP78的过度产生和PERK的磷酸化，这表明在高糖条件下培养的NRK-52E细胞中触发了内质网应激(ERS)。然而，用 GSK2606414 抑制 PERK 磷酸化阻断了 JAK2/STAT3 对NRK-52E 细胞中 TGF- β1和 ECM 成分产生的影响。结论。我们的数据表明，高糖诱导的 ECM 积累通过肾小管上皮细胞中的 PERK 依赖性 JAK2/STAT3 信号通路引起。