The epithelial-to-mesenchymal transition (EMT)-based tubulointerstitial fibrosis is the major pathological feature of diabetic kidney disease (DKD). While several studies have linked cell cycle dysregulation to various kidney injuries in recent years, its involvement in fibrosis of DKD is far from being clarified. ING2 (inhibitor of growth 2) is the second member of the inhibitor of growth family and participates in the regulation of many cellular processes. So far the role of ING2 in DKD remains largely unknown. In the present study, ING2 expression was detected by western blotting and immunofluorescent staining both in vitro high glucose-stimulated human proximal tubular epithelial cells (HK-2) and in vivo streptozotocin-induced diabetic mice. Cell proliferation was analyzed by CCK-8 and EdU assay, and cell cycle arrest was measured by flow cytometry. Quantitative polymerase chain reaction (qPCR) and western blotting were used to detect the EMT markers, and the p53 signaling activation was evaluated by chromatin immunoprecipitation (ChIP), qPCR, and western blotting. We found that the proliferation of the cells was reduced upon high glucose stimulation, which was accompanied by cell cycle arrest. The expression of ING2 was increased in hyperglycemia conditions both in vivo and in vitro. ING2 suppression ameliorated the reduced proliferation and cell cycle arrest induced by high glucose in HK-2 cells. Moreover, ING2 knockdown suppressed p21 expression by reducing p53 acetylation and finally alleviated the EMT progress in the high glucose-stimulated HK-2 cells. Our study demonstrated that cell cycle regulation is bound up with the kidney fibrosis in DKD, suggesting a novel function of ING2 as a potential therapeutic strategy targeting cell cycle arrest for DKD.

中文翻译：

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生长抑制剂2调节肾近端肾小管细胞中高葡萄糖诱导的细胞周期停滞和上皮向间充质转化。

基于上皮-间质转化（EMT）的肾小管间质纤维化是糖尿病肾病（DKD）的主要病理特征。尽管近年来有几项研究将细胞周期失调与各种肾脏损伤相关联，但其与DKD纤维化的关系尚不清楚。ING2（生长抑制剂2）是生长抑制剂家族的第二个成员，参与许多细胞过程的调节。迄今为止，ING2在DKD中的作用仍然未知。在本研究中，通过Western印迹和免疫荧光染色在体外高葡萄糖刺激的人近端肾小管上皮细胞（HK-2）和体内链脲佐菌素诱导的糖尿病小鼠中检测到ING2表达。通过CCK-8和EdU测定法分析细胞增殖，流式细胞仪检测细胞周期阻滞。使用定量聚合酶链反应（qPCR）和Western blotting检测EMT标记，并通过染色质免疫沉淀（ChIP），qPCR和Western blotting评估p53信号激活。我们发现，在高葡萄糖刺激下，细胞的增殖减少，并伴有细胞周期停滞。在体内和体外高血糖条件下，ING2的表达均增加。ING2抑制可改善HK-2细胞中高葡萄糖诱导的增殖减少和细胞周期停滞。此外，ING2敲低通过减少p53乙酰化抑制p21表达，并最终减轻了高葡萄糖刺激的HK-2细胞的EMT进展。