Specific receptor binding of renin on human mesangial cells in culture increases plasminogen activator inhibitor-1 antigen
Specific receptor binding of renin on human mesangial cells in culture increases plasminogen activator inhibitor-1 antigen
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DOI：
10.1038/ki.1996.511
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发表时间：
1996-12-01
影响因子：
19.6
通讯作者：
Sraer, JD
中科院分区：
文献类型：
--
作者：
Nguyen, G;Delarue, F;Sraer, JD
一些蛋白酶具有膜受体，其将蛋白水解活性集中在细胞表面上，并且可以介导增殖效应，例如尿激酶对肾小球上皮细胞的作用。由于一些高血压状态与高浓度的肾素和小动脉平滑肌细胞的增殖有关，我们询问了肾素（一种乙酰基蛋白酶）是否会与平滑肌衍生细胞系膜细胞结合，I-125标记重组人肾素（I-125-R）与血管内皮细胞的结合在人原代系膜细胞和转染SV 40-T抗原永生化系膜细胞上进行了研究。在37 ℃时，I-125-R的结合是时间依赖性的，并在两小时后达到平台。发现I-125-R以可饱和和特异性方式结合，对于原代和永生化细胞，Kd分别为0.4 nM和1 nM，结合位点分别为8，000和3，000个/细胞。当在合成的肾素抑制剂RO 42-5892存在下进行结合实验时，RO 43-5892仅在比IC 50上级1，000倍的浓度下才能抑制标记的肾素的特异性结合，表明肾素-系膜受体相互作用不依赖于肾素的活性位点。通过SDS-PAGE和放射自显影法分析与膜制备物结合的I-125-R的交联实验，显示约110至120 kDa的条带，表明肾素受体的Mr为70至80 kDa。用100 nM肾素孵育肾小球系膜细胞24小时，引起H-3胸苷掺入100%增加，即使孵育7天后，也不伴随细胞数量增加。然而，与肾素孵育的系膜细胞24小时诱导的纤溶酶原激活物抑制剂-1（PAI 1）抗原的条件培养基中的显着增加（170%的控制，P = 0.04）。总之，我们已经表明，培养的人肾小球系膜细胞表达一种特异性受体的肾素，和肾素的结合增加H-3胸苷掺入独立的肾素酶活性。细胞增殖的情况下，H-3胸苷掺入的增加和PAI 1抗原的增加表明，结合的肾素可以诱导系膜细胞活化，这是反映在细胞的纤溶能力的变化。该受体在与高血浆/组织肾素浓度、系膜或平滑肌细胞肥大和细胞外基质重塑相关的肾病和高血压状态中的作用仍有待确定。
Some proteases possess a membrane receptor that focalizes their proteolytic activity on the cell surface and may mediate a proliferative effect, such as urokinase on glomerular epithelial cells. Since some hypertensive states are associated with high concentrations of renin and proliferation of arteriolar smooth muscle cells, we asked whether renin, an aspartyl-protease, would bind to mesangial cells that are smooth-muscle derived cells, which would induce their proliferation The binding of I-125 labeled recombinant human renin (I-125-R) was studied on human primary mesangial cells and mesangial cells immortalized by transfection with SV40-T antigen. At 37 degrees C, the binding of I-125-R was time dependent and reached a plateau after two hours. I-125-R was found to bind in a saturable and specific manner with a K-d = 0.4 nM and 1 nM and 8,000 and 3,000 binding sites/cell, for primary and immortalized cells, respectively. When binding experiments were performed in the presence RO 42-5892, a synthetic inhibitor of renin, RO 43-5892 could inhibit the specific binding of labeled renin only at concentrations 1,000 times superior to the IC 50, indicating that the renin-mesangial receptor interaction did not depend on the active site of renin. Analysis by SDS-PAGE and autoradiography of cross-linking experiments of I-125-R bound to a membrane preparation showed a band of approximately 110 to 120 kDa, suggesting a Mr of 70 to 80 kDa for the renin receptor. Incubation of mesangial cells with 100 nM renin for 24 hours provoked a 100% increase of H-3 thymidine incorporation that was not accompanied by an increase of the cell number, even after a seven day period of incubation. However, the incubation of mesangial cells with renin for 24 hours induced a significant increase (170% of control, P = 0.04) of plasminogen activator inhibitor-1 (PAI1) antigen in the conditioned medium. In conclusion, we have shown that human mesangial cells in culture express a specific receptor for renin, and that the binding of renin increases H-3 thymidine incorporation independently of renin enzymatic activity. The absence of cell proliferation, the increase of H-3 thymidine incorporation and the increase of PAI1 antigen suggest that the binding of renin can induce mesangial cell activation, which is reflected by a change in the fibrinolytic capacity of the cells. The role of this receptor remains to be determined in nephropathies and hypertensive states associated with high plasma/tissue renin concentrations, hypertrophy of mesangial or smooth muscle cells and extracellular matrix remodeling.