白蛋白诱导的肾小管细胞凋亡与丝裂素激活蛋白激酶信号通路

目的 探讨白蛋白诱导肾小管上皮细胞凋亡以及诱导凋亡的信号传导机制｡ 方法 将培养的大鼠肾小管细胞NRK-52E分别与不同浓度(10､ 20､ 30 mg/ml)的去脂无内毒素牛血清白蛋白(BSA)共同孵育6､ 12､ 18和24 h｡透射电镜､共聚焦激光显微镜和流式细胞仪检测细胞凋亡｡BSA 20 mg/ml刺激NRK-52E细胞15､ 30､ 60和120 min后, Westen印迹测定p38､氨基末端激酶(JNK)和细胞外信号调节激酶(ERK)活性｡将SB202190(20 μmol/L, p38抑制剂)､SP600125(10 μmol/L, JNK抑制剂)和PD98059(20 μmol/L, ERK抑制剂)分别与白蛋白和NRK-52E细胞共同孵育24 h后检测细胞凋亡｡结果 白蛋白以时间和剂量依赖方式诱导肾小管细胞凋亡｡白蛋白与NRK-52E细胞共孵育后,p38和JNK活性明显升高,ERK活性显著降低｡SB202190和SP600125可分别抑制白蛋白诱导NRK-52E细胞凋亡,而PD98059促进白蛋白诱导的NRK-52E细胞凋亡｡结论 白蛋白以时间和剂量依赖方式诱导肾小管细胞凋亡,而p38和JNK激活与ERK抑制介导了白蛋白诱导的肾小管细胞凋亡｡

Albumin-induced rat tubular cell apoptosis and MAPKs signal transduction

Objective To evaluate the role of albumin and the involvement of mitogen-activated protein kinases(MAPKs) in rat tubular cells apoptosis. Methods Rat tubular cells (NRK-52E) were incubated with various concentrations (10, 20, 30 mg/ml) of delipidated, endotoxin-free bovine serum albumin(BSA) for 6, 12, 18 and 24 h, respectively. The process of apoptosis was evaluated by fluorescence microscope, transmission electron microscope, scanning electron microscope, confocal laser scanning microscope (CLSM) and flow cytometry. To assess the roles of p38, and the activities of JNK and ERK in albumin-induced apoptosis, SB202190 (20 μmol/L, p38 inhibitor), SP600125 (10 μmol/L, JNK inhibitor) or PD98059 (20 μmol/L, ERK inhibitor) were added to the NRK-52E cells separately in the presence of albumin for 24 hours. Activities of p38, JNK and ERK were assessed by Western blot analyses. Results The albumin induced tubular cell apoptosis in a dose- and time-dependent manner. Albumin stimulated the expression of p38 and JNK, whereas it inhibited the expression of ERK. SB202190 and SP600125 ameliorated tubular cells apoptosis but PD98059 treatment enhanced their apoptosis. Conclusions Albumin induces tabular cell apoptosis in a time- and dose-dependent manner in vitro, transducted through activation of p38 and JNK, and inhibition of ERK.