COAT-Platelets

COAT-血小板

• 批准号: 6717679
• 负责人: GEORGE LESLIE DALE
• 金额: $ 21.98万
• 依托单位: UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6717679
• 关键词: acid base balance; adduct; antifibrinolytic agents; binding sites; biological signal transduction; calcium; coagulation factor V; coagulation factor X; collagen; erythropoietin; fibrinogen; fibronectins; flow cytometry; hemostasis; human tissue; intracellular; laboratory mouse; phosphatidylserines; platelet activation; platelets; serotonin; surface coating; synthetic peptide; synthetic protein; thrombin; thrombospondins; von Willebrand factor

Platelets co-stimulated with collagen and thrombin display a number of unusual features. As initially described, these dual activated platelets, referred to a COAT-platelets (collagen and thrombin stimulated-platelets), express high levels of surface-bound factor V. This sub-population of platelets represents approximately 30 percent of the total and is most prominent among young platelets. COAT-platelets are also observed upon activation with thrombin plus convulxin, an agonist for glycoprotein VI; however, no single agonist examined was able to produce COAT-platelets. The functional significance of FV on COAT-platelets was shown by demonstrating high factor V activity, preferential binding of factor Xa and significant prothrombinase activity. In addition, COAT-platelets were found to have several other alpha-granule proteins including von Willebrand factor, fibrinogen, fibronectin, thrombospondin and alpha2-antiplasmin, bound at high levels. Unexpectedly, COAT-platelet formation is prevented by transglutaminase inhibitors including dansyl cadaverine, putrescine, and acetyl-casein, and a synthetic peptide substrate for transglutaminases is incorporated in COAT- platelets. The platelet component serving as the acyl acceptor for the transglutaminase reaction was found to be serotonin, and multi-valent serotonin-adducts of albumin were effective inhibitors of COAT-platelet formation. Fibrinogen isolated from COAT-platelets was also found to have conjugated serotonin. This proposal will further characterize COAT-platelets by identifying serotonin-adducts of other alpha-granule proteins found on COAT- platelets, by characterizing the serotonin binding sites present on COAT-platelets, and by evaluating the physiological manipulation of COAT-platelets in experimental animals.

与胶原蛋白和凝血酶共同刺激的血小板显示出许多不寻常的特征。 正如最初所描述的，这些双重激活的血小板，称为 COAT 血小板（胶原和凝血酶刺激的血小板），表达高水平的表面结合因子 V。这一血小板亚群约占总数的 30%，在年轻血小板中最为突出。 用凝血酶加惊旋蛋白（一种糖蛋白 VI 的激动剂）激活后也可观察到 COAT 血小板；然而，所检测的单一激动剂均无法产生 COAT 血小板。 FV 在 COAT 血小板上的功能意义通过证明高因子 V 活性、因子 Xa 的优先结合和显着的凝血酶原酶活性来显示。 此外，还发现 COAT 血小板具有高水平结合的其他几种 α 颗粒蛋白，包括血管性血友病因子、纤维蛋白原、纤连蛋白、血小板反应蛋白和 α2-抗纤溶酶。 出乎意料的是，转谷氨酰胺酶抑制剂（包括丹酰尸胺、腐胺和乙酰酪蛋白）阻止了COAT-血小板的形成，并且转谷氨酰胺酶的合成肽底物掺入COAT-血小板中。 发现作为转谷氨酰胺酶反应酰基受体的血小板成分是血清素，白蛋白的多价血清素加合物是COAT-血小板形成的有效抑制剂。 从 COAT 血小板中分离出的纤维蛋白原也被发现具有结合的血清素。 该提案将通过鉴定 COAT 血小板上发现的其他 α 颗粒蛋白的血清素加合物、通过表征 COAT 血小板上存在的血清素结合位点以及评估实验动物中 COAT 血小板的生理操作来进一步表征 COAT 血小板。