LSD1在急性肾损伤后肾小管上皮细胞再生修复中的作用和机制

Lysine specific demethylase 1 (LSD1), a histone demethylase critically involved in regulating the activation and repression of gene transcription, is closely associated with cell proliferation. The proliferation of residual renal epithelial cells is the major process of renal repair after acute kidney injury (AKI). Our preliminary studies have demonstrated that administration of LSD1 inhibitor significantly improved renal function and tubular injury after ischemia-reperfusion (IR)-induced AKI. Inhibition of LSD1 activity also enhanced the activation and expression of epidermal growth factor receptor (EGFR). These data suggest that LSD1 plays an important role in the regulation of renal repair and renal regeneration after AKI and in mediating EGFR activation. However, the underlying mechanism is still unclear. In this study, by using proteomics, gene silencing and immunofluorescence techniques, we will first confirm the activation and expression of LSD1 and histone methylation in RPTC after oxidative injury. Second, we will explore the molecular mechanisms of LSD1 in cell regeneration in RPTC after oxidative injury. Third, we will further assess the role of LSD1 in renal regeneration after IR-induced AKI using LSD1 siRNA. Successful completion of these studies will provide a theoretical basis for the role of LSD1 in renal repair and regeneration after AKI and will lay the foundation for promotion of targeted therapy in kidney regeneration after AKI.

LSD1是一种组蛋白去甲基化酶，调控基因转录的激活和抑制，与细胞增殖调控密切相关。残存肾小管上皮细胞的增殖是急性肾损伤（AKI）后肾脏再生修复的主要环节。前期研究发现：应用赖氨酸特异性去甲基化酶1（LSD1）抑制剂可明显改善缺血再灌注(IR)诱导AKI后的肾功能恢复，减轻肾小管损伤，并增加表皮生长因子受体（EGFR）的磷酸化水平，提示LSD1在AKI后肾脏再生修复和EGFR活化过程中起重要调节作用，但目前机制不明。本研究将应用蛋白组学、基因沉默，免疫荧光等技术，（1）明确肾小管上皮细胞氧化损伤后LSD1在细胞再生中的作用；（2）探讨LSD1介导肾小管上皮细胞氧化损伤后细胞再生的分子机制；(3)利用LSD1小分子干扰RNA，进一步评估LSD1在小鼠AKI后肾脏再生修复中的作用。为LSD1在AKI后肾脏再生修复中的作用提供理论依据，为促进肾脏再生的靶向治疗奠定基础。

JMJD3是一种组蛋白去甲基化酶，可特征性地降低H3K27二甲基化和三甲基化水平，调控基因转录的激活和抑制，与细胞增殖调控密切相关。残存肾小管上皮细胞的增殖是急性肾损伤（AKI）后肾脏再生修复的主要环节。初步研究发现应用JMJD3抑制剂进一步加重GL-诱导AKI小鼠的肾功能水平，加重肾小管间质损伤，但具体机制不明。本研究应用蛋白组学、免疫印记、免疫荧光等技术，通过建立甘油（GL）横纹肌溶解诱导急性肾损伤（AKI）小鼠模型，应用去甲基化酶JMJD3抑制剂GSK J4，阐明JMJD3在小鼠急性肾损伤后肾脏再生修复中的作用；及探讨JMJD3介导肾脏再生修复的作用机制。我们研究表明，去甲基化酶JMJD3抑制剂GSK J4通过增加组蛋白H3赖氨酸第27位点二甲基化和三甲基化水平在急性肾损伤后肾脏再生修复过程中起着重要作用，应用GSK J4抑制JMJD3活性加重GL-诱导急性肾损伤小鼠的肾脏损伤，表现为加重肾功能恶化，血肌酐水平较急性肾损伤模型组进一步升高，肾脏病理表现为显著肾小管肿胀、扩张、溶解、肾小管管型形成。应用GSK J4抑制JMJD3活性在GL-诱导AKI小鼠促进肾小管上皮细胞凋亡、抑制肾小管上皮细胞再生修复的去分化及增殖过程。机制研究表明，应用GSK J4抑制JMJD3活性明显增加p-NF-κB表达，同时促进其下游的促炎因子TNF-α及IL-6释放；另一方面应用GSK J4抑制JMJD3活性显著抑制EGFR的活化及表达，同时明显下调其下游STAT3及AKT的活化。这些结果表明，抑制JMJD3活性加重GL-诱导急性肾损伤小鼠肾脏损伤，其机制可能通过活化NF-κB信号途径并诱导下游促炎因子释放，以及抑制EGFR/STAT3及EGFR/AKT信号途径的活化。这些结果为JMJD3在急性肾损伤后肾脏再生修复中应用提供重要的理论依据，为研发急性肾损伤治疗靶向药物奠定重要的理论基础。