血管紧张素II诱导的足细胞凋亡是由内质网应激/PKC-δ/p38丝裂原活化蛋白激酶途径激活介导的，并通过增加钠/氢交换体1的活性来实现。

Angiotensin II-induced podocyte apoptosis is mediated by endoplasmic reticulum stress/PKC-δ/p38 MAPK pathway activation and trough increased Na/H exchanger isoform 1 activity.

作者信息

Cardoso Vanessa Gerolde, Gonçalves Guilherme Lopes, Costa-Pessoa Juliana Martins, Thieme Karina, Lins Bruna Bezerra, Casare Fernando Augusto Malavazzi, de Ponte Mariana Charleaux, Camara Niels Olsen Saraiva, Oliveira-Souza Maria

机构信息

Laboratory of Renal Physiology, Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, 05508-900, Brazil.

Laboratory of Carbohydrates and Radioimmunoassays (LIM-18), Medical School, University of Sao Paulo, Sao Paulo, Brazil.

出版信息

BMC Nephrol. 2018 Jul 13;19(1):179. doi: 10.1186/s12882-018-0968-4.

BACKGROUND

Angiotensin II (Ang II) contributes to the progression of renal diseases associated with proteinuria and glomerulosclerosis mainly by inducing podocyte apoptosis. In the present study, we investigated whether the chronic effects of Ang II via AT1 receptor (AT1R) would result in endoplasmic reticulum (ER) stress/PKC-delta/p38 MAPK stimulation, and consequently podocyte apoptosis.

METHODS

Wistar rats were treated with Ang II (200 ng·kg·min, 42 days) and or losartan (10 mg·kg·day, 14 days). Immortalized mouse podocyte were treated with 1 μM Ang II and/or losartan (1 μM) or SB203580 (0.1 μM) (AT1 receptor antagonist and p38 MAPK inhibitor) for 24 h. Kidney sections and cultured podocytes were used to evaluate protein expression by immunofluorescence and immunoblotting. Apoptosis was evaluated by flow cytometry and intracellular pH (pHi) was analyzed using microscopy combined with the fluorescent probe BCECF/AM.

RESULTS

Compared with controls, Ang II via AT1R increased chaperone GRP 78/Bip protein expression in rat glomeruli (p < 0.001) as well as in podocyte culture (p < 0.01); increased phosphorylated eIf2-α (p < 0.05), PKC-delta (p < 0.01) and p38 MAPK (p < 0.001) protein expression. Furthermore, Ang II induced p38 MAPK-mediated late apoptosis and increased the Bax/Bcl-2 ratio (p < 0.001). Simultaneously, Ang II via AT1R induced p38 MAPK-NHE1-mediated increase of pHi recovery rate after acid loading.

CONCLUSION

Together, our results indicate that Ang II-induced podocyte apoptosis is associated with AT1R/ER stress/PKC-delta/p38 MAPK axis and enhanced NHE1-mediated pHi recovery rate.

背景

血管紧张素II（Ang II）主要通过诱导足细胞凋亡，促进与蛋白尿和肾小球硬化相关的肾脏疾病进展。在本研究中，我们调查了Ang II通过1型血管紧张素受体（AT1R）产生的慢性影响是否会导致内质网（ER）应激/蛋白激酶C-δ（PKC-δ）/p38丝裂原活化蛋白激酶（MAPK）激活，进而导致足细胞凋亡。

方法

用Ang II（200 ng·kg·min，42天）和/或氯沙坦（10 mg·kg·天，14天）处理Wistar大鼠。用1 μM Ang II和/或氯沙坦（1 μM）或SB203580（0.1 μM）（AT1受体拮抗剂和p38 MAPK抑制剂）处理永生化小鼠足细胞24小时。用肾脏切片和培养的足细胞通过免疫荧光和免疫印迹评估蛋白表达。通过流式细胞术评估细胞凋亡，并使用显微镜结合荧光探针2',7'-双（羧乙基）-5（6）-羧基荧光素乙酰甲酯（BCECF/AM）分析细胞内pH值（pHi）。

结果

与对照组相比，通过AT1R的Ang II增加了大鼠肾小球（p < 0.001）以及足细胞培养物（p < 0.01）中伴侣蛋白葡萄糖调节蛋白78（GRP 78）/免疫球蛋白重链结合蛋白（Bip）的蛋白表达；增加了磷酸化真核细胞起始因子2α（eIf2-α）（p < 0.05）、PKC-δ（p < 0.01）和p38 MAPK（p < 0.001）的蛋白表达。此外，Ang II诱导p38 MAPK介导的晚期凋亡并增加了Bax与Bcl-2的比率（p < 0.001）。同时，通过AT1R的Ang II诱导p38 MAPK-钠氢交换体1（NHE1）介导的酸负荷后pHi恢复率增加。