Department of Medicine, University of California, San Diego, La Jolla, CA 92161, USA
Blood. 2011 Jun 30;117(26):7155-63. doi: 10.1182/blood-2010-05-287672. Epub 2011 May 19.
Recent studies suggest a crucial role for plasminogen activator inhibitor-1 (PAI-1) in mediating stress-induced hypercoagulability and thrombosis. However, the mechanisms by which PAI-1 is released by stress are not well-delineated. Here, we examined catecholaminergic neurosecretory cells for expression, trafficking, and release of PAI-1. PAI-1 was prominently expressed in PC12 pheochromocytoma cells and bovine adrenomedullary chromaffin cells as detected by Northern blotting, Western blotting, and specific PAI-1 ELISA. Sucrose gradient fractionation studies and immunoelectron microscopy demonstrated localization of PAI-1 to catecholamine storage vesicles. Secretogogue stimulation resulted in corelease of PAI-1 with catecholamines. Parallel increases in plasma PAI-1 and catecholamines were observed in response to acute sympathoadrenal activation by restraint stress in mice in vivo. Reverse fibrin zymography demonstrated free PAI-1 in cellular releasates. Detection of high molecular weight complexes by Western blotting, consistent with PAI-1 complexed with t-PA, as well as bands consistent with cleaved PAI-1, suggested that active PAI-1 was present. Modulation of PAI-1 levels by incubating PC12 cells with anti-PAI-1 IgG caused a marked decrease in nicotine-mediated catecholamine release. In summary, PAI-1 is expressed in chromaffin cells, sorted into the regulated pathway of secretion (into catecholamine storage vesicles), and coreleased, by exocytosis, with catecholamines in response to secretogogues.
最近的研究表明，纤溶酶原激活物抑制剂-1（PAI-1）在介导应激诱导的高凝状态和血栓形成中起着关键作用。然而，应激导致 PAI-1 释放的机制还没有很好地阐明。在这里，我们研究了儿茶酚胺能神经分泌细胞中 PAI-1 的表达、运输和释放。通过 Northern blot、Western blot 和特异性 PAI-1 ELISA 检测，PAI-1 在 PC12 嗜铬细胞瘤细胞和牛肾上腺髓质嗜铬细胞中表达明显。蔗糖梯度分级分离研究和免疫电镜显示 PAI-1 定位于儿茶酚胺储存小泡。刺激分泌剂可导致 PAI-1 与儿茶酚胺共同释放。在体内，用束缚应激急性刺激交感肾上腺，观察到血浆 PAI-1 和儿茶酚胺同时增加。反向纤维蛋白溶酶原活性测定显示细胞释放物中有游离的 PAI-1。Western blot 检测到高分子量复合物，与 PAI-1 与 t-PA 结合一致，以及与裂解的 PAI-1 一致的条带，提示存在有活性的 PAI-1。用抗 PAI-1 IgG 孵育 PC12 细胞来调节 PAI-1 水平，可显著减少烟碱介导的儿茶酚胺释放。总之，PAI-1 在嗜铬细胞中表达，被分拣到分泌的调节途径（进入儿茶酚胺储存小泡），并通过胞吐作用与儿茶酚胺共同释放，作为对分泌剂的反应。
