血管紧张素IV刺激近端肾小管上皮细胞中纤溶酶原激活物抑制剂-1的表达。

Angiotensin IV stimulates plasminogen activator inhibitor-1 expression in proximal tubular epithelial cells.

作者信息

Gesualdo L, Ranieri E, Monno R, Rossiello M R, Colucci M, Semeraro N, Grandaliano G, Schena F P, Ursi M, Cerullo G

机构信息

Dipartimento dell'Emergenza e dei Trapianti di Organi, Sezione di Nefrologia, Policlinico, Bari, Italy.

出版信息

Kidney Int. 1999 Aug;56(2):461-70. doi: 10.1046/j.1523-1755.1999.00578.x.

DOI:10.1046/j.1523-1755.1999.00578.x

PMID:10432384

Abstract

BACKGROUND

Angiotensin II (Ang II) has been shown to be implicated in the development of renal fibrosis in several forms of chronic glomerulonephritides, but the precise mechanisms of its effects remain unclear. It has recently been reported that Ang II stimulates the expression of plasminogen activator inhibitor-1 (PAI-1) in several cell lines. PAI-1 is a major physiological inhibitor of the plasminogen activator/plasmin system, a key regulator of fibrinolysis and extracellular matrix (ECM) turnover. PAI-1 induction by Ang II in endothelial cells seems to be mediated by Ang IV via a receptor that is different from Ang II type 1 and 2 receptors (AT1 and AT2).

METHODS

In this study, we sought to evaluate the effects of Ang IV on PAI-1 gene and protein expression in a well-characterized and immortalized human proximal tubular cell line (HK2) by Northern blot and enzyme-linked immunosorbent assay.

RESULTS

Ang IV stimulated PAI-1 mRNA expression, whereas it did not induce a significant increase in tritiated thymidine uptake after 24 hours of incubation. This effect was dose and time dependent. Ang IV (10 nM) induced a 7.8 +/- 3.3-fold increase in PAI-1 mRNA expression. The PAI-1 antigen level was significantly higher in conditioned media and the ECM of cells treated with Ang II and Ang IV than in control cells (both P < 0.02). Although Ang II induced a 4.2 +/- 2. 1-fold increase in PAI-1 mRNA expression, its effect underwent a dose-dependent reduction when amastatin, a potent inhibitor of the endopeptidases that catalyzes the conversion of Ang II to Ang IV, was added. In contrast, amastatin was not able to prevent the expression of PAI-1 mRNA induced by Ang IV. Finally, pretreatment of HK2 cells with losartan and N-Nicotinoyl-Tyr-N3-(Nalpha-CBZ-Arg)-Lys-His-Pro-Ile, the specific antagonists of AT1 and AT2 receptors, failed to modify PAI-1 mRNA expression as induced by Ang II.

CONCLUSIONS

Our results demonstrate that Ang II stimulates PAI-1 mRNA expression and the production of its protein in human proximal tubular cells. This is mainly-if not exclusively-due to Ang IV, which acts on a receptor that is different than AT1 or AT2. Therefore, it can be hypothesized that the induction of PAI-1 by Ang IV may be implicated in the pathogenesis of renal interstitial fibrosis in several forms of chronic glomerulonephritides.

摘要

背景

血管紧张素II（Ang II）已被证明在多种形式的慢性肾小球肾炎的肾纤维化发展中起作用，但其作用的确切机制仍不清楚。最近有报道称，Ang II可刺激几种细胞系中纤溶酶原激活物抑制剂-1（PAI-1）的表达。PAI-1是纤溶酶原激活物/纤溶酶系统的主要生理抑制剂，是纤维蛋白溶解和细胞外基质（ECM）周转的关键调节因子。Ang II在内皮细胞中诱导PAI-1似乎是由Ang IV通过一种不同于Ang II 1型和2型受体（AT1和AT2）的受体介导的。

方法

在本研究中，我们试图通过Northern印迹和酶联免疫吸附测定法评估Ang IV对一种特征明确的永生化人近端肾小管细胞系（HK2）中PAI-1基因和蛋白表达的影响。

结果

Ang IV刺激PAI-1 mRNA表达，而在孵育24小时后，它并未诱导氚标记胸腺嘧啶摄取的显著增加。这种作用是剂量和时间依赖性的。Ang IV（10 nM）诱导PAI-1 mRNA表达增加7.8±3.3倍。用Ang II和Ang IV处理的细胞的条件培养基和ECM中的PAI-1抗原水平明显高于对照细胞（均P<0.02）。虽然Ang II诱导PAI-1 mRNA表达增加4.2±2.1倍，但当加入氨肽酶抑制剂氨肽素（一种催化Ang II转化为Ang IV的内肽酶的有效抑制剂）时，其作用呈剂量依赖性降低。相反，氨肽素不能阻止Ang IV诱导的PAI-1 mRNA表达。最后，用氯沙坦和N-烟酰基-Tyr-N3-（Nα-CBZ-精氨酸）-赖氨酸-组氨酸-脯氨酸-异亮氨酸（AT1和AT2受体的特异性拮抗剂）预处理HK2细胞，未能改变Ang II诱导的PAI-1 mRNA表达。