组蛋白H3K27甲基转移酶EZH2在顺铂致急慢性肾损伤中的作用和机制研究

Cisplantin is an extensively used anti-tumor drug, however, it frequently causes acute and chronic kidney injury. Currently, there is no available approach to prevent and treat cisplantin-related kidney diseases. We have previously found that EZH2, a histone H3K27 methyltransferase, is highly expressed in the kidney after acute kidney injury (AKI)and chronic kidney fibrosis; pharmaceutical inhibition of EZH2 could significantly improve renal dysfunction and attenuate renal tubular injury and fibrosis. This suggests that expression of EZH2 is associated with development and progression of acute and chronic renal injury. By utilizing animal models of acute kidney injury and renal fibrosis, pharmaceutical inhibitors, and conditional knockout mice of EZH2 in proximal renal tubular cells, and a variety of molecular techniques, we will (1) evaluate the effect of EZH2 inhibition on the pathogenesis of AKI and renal dysfunction; (2) explore the mechanism of EZH2-elicited death of renal tubular cells, and (3) elucidate the role and mechanisms of EZH2 in regulating cisplantin-elicited renal fibrosis. Therefore, the successful completion of this project will lay down the ground work for identification of novel targets for treatment of acute and chronic renal injury and development of epigenetic drugs for preventing and treating nephrotoxic diseases.

顺铂是一种广泛应用的抗肿瘤药,但常致急慢性肾损害。目前尚无有效防治措施。我们课题组前期研究发现:组蛋白H3K27甲基化转移酶EZH2在急性肾损伤(AKI)和慢性纤维化的肾脏高表达,药物抑制EZH2明显改善急性缺血/再灌注和顺铂引起的AKI后肾功能障碍,并减轻肾小管损伤和肾脏纤维化。提示EZH2表达与急慢性肾损伤的发生发展密切相关。本研究拟利用顺铂致急性和慢性肾损伤模型，EZH2药物抑制剂及基因敲除小鼠和各种分子生物学手段，首先评估EZH2抑制对顺铂致AKI病理和肾功能障碍的影响;其次探讨EZH2介导肾小管细胞死亡的机制;最后阐明EZH2在顺铂引起的肾脏纤维化中的作用和机制。本研究将为探求治疗急慢性肾损伤的新靶点，研发防治中毒性肾病的表观遗传药物奠定基础。

本课题的研究目的在于明确组蛋白H3K27甲基转移酶EZH2 在顺铂致急慢性肾损伤中的作用和机制。利用顺铂致急性肾损伤（AKI）小鼠的模型，发现药物（3-DZNep）抑制EZH2明显减轻顺铂导致的肾脏病理改变和肾小管上皮细胞的损伤与凋亡，并改善肾功能，保持E-cadherin表达在接近正常水平。同样，在急性肾缺血/再灌注导致的小鼠AKI模型中， 3-DZNep处理也抑制肾组织损伤以及肾小管细胞凋亡，并改善肾功能、抑制E-cadherin的降解。此外，在体外培养的肾小管上皮细胞， 3-DZNep 处理或转染EZH2 siRNA抑制氧化应激引起的细胞凋亡。这些结果提示EZH2介导急性肾小管细胞的损伤。虽然，在我们的实验过程中，低剂量顺铂未能成功的诱导肾脏纤维化，但发现药物阻断EZH2可减轻尿酸导致的慢性肾脏损伤和纤维性反应。此外，利用肾小管和肾间质细胞敲除的小鼠以及降解EZH2的药物，我们也发现减少肾脏EZH2的表达可抑制肾成纤维细胞激活和肾小管上皮细胞的纤维化表型转变，减轻肾脏纤维化；相反，在药物抑制或敲低肾小管和肾间质细胞JMJD3（一种组蛋白H3K27的去甲基化酶）的小鼠，促进这些细胞表型的转变和加重肾脏纤维化。因此，EZH2上调或/和活性增加促进 急慢性肾损伤中的发生与发展。EZH2可能成为治疗急慢性肾损伤的新的潜在靶点