Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon 21999, Republic of Korea.
College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon 21936, Republic of Korea.
Int J Mol Sci. 2023 Jun 9;24(12):9968. doi: 10.3390/ijms24129968.
Podocyte damage and renal inflammation are the main features and pathogenesis of diabetic nephropathy (DN). Inhibition of lysophosphatidic acid (LPA) receptor 1 (LPAR1) suppresses glomerular inflammation and improves DN. Herein, we investigated LPA-induced podocyte damage and its underlying mechanisms in DN. We investigated the effects of AM095, a specific LPAR1 inhibitor, on podocytes from streptozotocin (STZ)-induced diabetic mice. E11 cells were treated with LPA in the presence or absence of AM095, and the expression of NLRP3 inflammasome factors and pyroptosis were measured. A chromatin immunoprecipitation assay and Western blotting were performed to elucidate underlying molecular mechanisms. Gene knockdown by transfecting small interfering RNA was used to determine the role of the transcription factor Egr1 (early growth response protein 1) and histone methyltransferase EzH2 (Enhancer of Zeste Homolog 2) in LPA-induced podocyte injury. AM095 administration inhibited podocyte loss, NLRP3 inflammasome factor expression, and cell death in STZ-induced diabetic mice. In E11 cells, LPA increased NLRP3 inflammasome activation and pyroptosis via LPAR1. Egr1 mediated NLRP3 inflammasome activation and pyroptosis in LPA-treated E11 cells. LPA decreased H3K27me3 enrichment at the Egr1 promoter in E11 cells by downregulating EzH2 expression. EzH2 knockdown further increased LPA-induced Egr1 expression. In podocytes from STZ-induced diabetic mice, AM095 suppressed Egr1 expression increase and EzH2/H3K27me3 expression reduction. Collectively, these results demonstrate that LPA induces NLRP3 inflammasome activation by downregulating EzH2/H3K27me3 and upregulating Egr1 expression, resulting in podocyte damage and pyroptosis, which may be a potential mechanism of DN progression.
足细胞损伤和肾脏炎症是糖尿病肾病(DN)的主要特征和发病机制。抑制溶血磷脂酸(LPA)受体 1(LPAR1)可抑制肾小球炎症并改善 DN。在此,我们研究了 LPA 在 DN 中诱导的足细胞损伤及其潜在机制。我们研究了特异性 LPAR1 抑制剂 AM095 对链脲佐菌素(STZ)诱导的糖尿病小鼠足细胞的影响。在存在或不存在 AM095 的情况下,用 LPA 处理 E11 细胞,并测量 NLRP3 炎性体因子和细胞焦亡的表达。进行染色质免疫沉淀测定和 Western blot 以阐明潜在的分子机制。通过转染小干扰 RNA 进行基因敲低,以确定转录因子 Egr1(早期生长反应蛋白 1)和组蛋白甲基转移酶 EzH2(增强子结合锌指蛋白 2)在 LPA 诱导的足细胞损伤中的作用。AM095 给药抑制了 STZ 诱导的糖尿病小鼠中足细胞丢失、NLRP3 炎性体因子表达和细胞死亡。在 E11 细胞中,LPA 通过 LPAR1 增加 NLRP3 炎性体激活和细胞焦亡。Egr1 介导 LPA 处理的 E11 细胞中 NLRP3 炎性体激活和细胞焦亡。LPA 通过下调 EzH2 表达降低 E11 细胞中 Egr1 启动子处 H3K27me3 的富集。EzH2 敲低进一步增加了 LPA 诱导的 Egr1 表达。在 STZ 诱导的糖尿病小鼠的足细胞中,AM095 抑制了 Egr1 表达增加和 EzH2/H3K27me3 表达减少。总之,这些结果表明,LPA 通过下调 EzH2/H3K27me3 和上调 Egr1 表达诱导 NLRP3 炎性体激活,导致足细胞损伤和细胞焦亡,这可能是 DN 进展的潜在机制。