Gerald Soslau, PhD, Office of Professional Studies in the Health Sciences, Drexel University College of Medicine, 245 N 15th Street, Philadelphia, PA 19102, USA, Tel.: +1 215 762 7831, Fax: +1 215 762 7434, E-mail:
Thromb Haemost. 2014 Jan;111(1):140-53. doi: 10.1160/TH13-03-0248. Epub 2013 Oct 17.
Matrix metalloproteinase (MMP) activity is generally associated with normal or pathological extracellular processes such as tissue remodelling in growth and development or in tumor metastasis and angiogenesis. Platelets contain at least three MMPs, 1, 2 and 9 that have been reported to stimulate or inhibit agonist-induced platelet aggregation via extracellular signals. The non-selective Zn+2 chelating MMP inhibitor, 1,10-phenanthroline, and the serine protease inhibitor, AEBSF, were found to inhibit all tested agonist-induced platelet aggregation reactions. In vitro analysis demonstrated that 1,10-phenanthroline completely inhibited MMP-1,2,and 9 but had little to no effect on calpain activity while the converse was true with AEBSF. We now demonstrate that MMP-2 functions intracellularly to regulate agonist-induced platelet aggregations via the hydrolytic activation of talin, the presumed final activating factor of glycoprotein (GP)IIb/IIIa integrin (the inside-out signal). Once activated GPIIb/IIIa binds the dimeric fibrinogen molecule required for platelet aggregation. The active intracellular MMP-2 molecule is complexed with JAK 2/STAT 3, as demonstrated by the fact that all three proteins are co-immunoprecipitated with either anti-JAK 2, or anti-STAT 3 antibodies and by immunofluorescence studies. The MMP-2 platelet activation pathway can be synergistically inhibited with the non-selective MMP inhibitor, 1,10-phenanthroline, plus a JAK 2 inhibitor. This activation pathway is distinct from the previously reported calpain-talin activating pathway. The identification of a new central pathway for platelet aggregation presents new potential targets for drug regulation and furthers our understanding of the complexity of platelet activation mechanisms.
基质金属蛋白酶（MMP）活性通常与正常或病理细胞外过程相关，例如生长和发育过程中的组织重塑或肿瘤转移和血管生成。血小板至少含有三种 MMP，1、2 和 9，据报道它们通过细胞外信号刺激或抑制激动剂诱导的血小板聚集。非选择性 Zn+2 螯合 MMP 抑制剂 1,10-菲咯啉和丝氨酸蛋白酶抑制剂 AEBSF 被发现抑制所有测试的激动剂诱导的血小板聚集反应。体外分析表明，1,10-菲咯啉完全抑制 MMP-1、2 和 9，但对钙蛋白酶活性几乎没有影响，而 AEBSF 则相反。我们现在证明 MMP-2 在内质网中通过水解激活血栓调节蛋白（被认为是糖蛋白（GP）IIb/IIIa 整合素（内向外信号）的最终激活因子）来调节激动剂诱导的血小板聚集。一旦被激活，GPIIb/IIIa 就会结合二聚体纤维蛋白原分子，这是血小板聚集所必需的。活性的细胞内 MMP-2 分子与 JAK 2/STAT 3 结合，这一事实通过以下事实证明：三种蛋白质都与抗 JAK 2 或抗 STAT 3 抗体共免疫沉淀，并且通过免疫荧光研究。可以用非选择性 MMP 抑制剂 1,10-菲咯啉加上 JAK 2 抑制剂协同抑制 MMP-2 血小板激活途径。该激活途径与先前报道的钙蛋白酶-血栓调节蛋白激活途径不同。血小板聚集新的中央途径的确定为药物调节提供了新的潜在靶点，并进一步加深了我们对血小板激活机制复杂性的理解。
