Activation of a local tissue angiotensin system in podocytes by mechanical strain
Activation of a local tissue angiotensin system in podocytes by mechanical strain
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DOI：
10.1111/j.1523-1755.2004.00362.x
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发表时间：
2004-01-01
影响因子：
19.6
通讯作者：
Shankland, SJ
中科院分区：
文献类型：
--
作者：
Durvasula, RV;Petermann, AT;Shankland, SJ
背景肾小球毛细血管高血压是各种形式的进行性肾小球疾病的共同特征，导致毛细血管丛的机械扩张，以及随后的上覆足细胞层的损伤。肾小球内压升高转化为足细胞适应不良反应的机制仍知之甚少。血管紧张素II在慢性肾损伤的发病机制中起核心作用，主要是通过其对亚型1受体的作用。因此，我们已经测试了这样的假设，即机械应变上调局部血管紧张素II在足细胞，从而导致足细胞数量的进行性减少。对条件永生化小鼠足细胞进行10%幅度的周期性拉伸。未拉伸足细胞作为对照。通过竞争性酶联免疫吸附试验（ELISA）测定全细胞裂解物中的血管紧张素II水平。采用定量聚合酶链反应（PCR）和Western blot分析检测血管紧张素II受体（AT（1）R，AT（2）R）的表达。Hoechst染色检测细胞凋亡。在5/6残肾病大鼠（肾小球高血压模型）的组织切片中进行AT（1）R的免疫染色。在24、48和72小时，机械牵拉增加足细胞中血管紧张素II的产生（P < 0.05，与未牵拉的对照相比）。与对照组相比，伸展足细胞24小时AT（1）R mRNA表达增加5倍，蛋白水平增加2倍（P < 0.05），转化生长因子β（TGF-β）mRNA表达也增加。AT（1）R染色在5/6残肾的足细胞分布中增加，与我们的体外发现一致。机械应变导致细胞凋亡增加2.5倍（P
Background. Glomerular capillary hypertension, a common denominator in various forms of progressive glomerular disease, results in mechanical distention of the capillary tuft, and subsequent injury of the overlying podocyte layer. The mechanisms by which elevated intraglomerular pressure is translated into a maladaptive podocyte response remain poorly understood. Angiotensin II plays a central role in the pathogenesis of chronic renal injury, largely through its actions on the subtype 1 receptor. Accordingly, we have tested the hypothesis that mechanical strain up-regulates local angiotensin II in podocytes, thereby resulting in a progressive reduction in podocyte number.Methods. Conditionally immortalized mouse podocytes were subjected to cyclical stretch of 10% amplitude. Nonstretched podocytes served as controls. Angiotensin II levels were measured in whole cell lysate by competitive enzyme-linked immunosorbent assay (ELISA). Expression of angiotensin II receptors (AT(1)R, AT(2)R) was measured by quantitative polymerase chain reaction (PCR) and Western blot analysis. Apoptosis was measured by Hoechst staining. Immunostaining for AT(1)R was performed in tissue sections from rats with 5/6 remnant kidney disease, a model of glomerular hypertension.Results. Mechanical strain increased angiotensin II production in podocytes at 24, 48, and 72 hours (P < 0.05 vs. nonstretched controls). Stretching podocytes resulted in a fivefold increase in AT(1)R mRNA expression at 24 hours and a twofold increase in protein levels vs. controls (P < 0.05), and also an increase in transforming growth hormone-beta (TGF-beta) mRNA expression. AT(1)R staining was increased in a podocyte distribution in the 5/6 remnant kidney, consistent with our in vitro findings. Mechanical strain resulted in a 2.5-fold increase in apoptosis (P