Tibbles H E, Vassilev A, Wendorf H, Schonhoff D, Zhu D, Lorenz D, Waurzyniak B, Liu X P, Uckun F M
Parker Hughes Cancer Center, Departments of Hematology, Parker Hughes Institute, St. Paul, Minnesota, 55113, USA.
J Biol Chem. 2001 May 25;276(21):17815-22. doi: 10.1074/jbc.M011405200. Epub 2001 Feb 22.
Here we provide experimental evidence that identifies JAK3 as one of the regulators of platelet function. Treatment of platelets with thrombin induced tyrosine phosphorylation of the JAK3 target substrates STAT1 and STAT3. Platelets from JAK3-deficient mice displayed a decrease in tyrosine phosphorylation of STAT1 and STAT3. In accordance with these data, pretreatment of human platelets with the JAK3 inhibitor WHI-P131 markedly decreased the base-line enzymatic activity of constitutively active JAK3 and abolished the thrombin-induced tyrosine phosphorylation of STAT1 and STAT3. Following thrombin stimulation, WHI-P131-treated platelets did not undergo shape changes indicative of activation such as pseudopod formation. WHI-P131 inhibited thrombin-induced degranulation/serotonin release as well as platelet aggregation. Highly effective platelet inhibitory plasma concentrations of WHI-P131 were achieved in mice without toxicity. WHI-P131 prolonged the bleeding time of mice in a dose-dependent manner and improved event-free survival in a mouse model of thromboplastin-induced generalized and invariably fatal thromboembolism. To our knowledge, WHI-P131 is the first anti-thrombotic agent that prevents platelet aggregation by inhibiting JAK3.
在此，我们提供实验证据，确定JAK3为血小板功能的调节因子之一。用凝血酶处理血小板可诱导JAK3靶底物STAT1和STAT3的酪氨酸磷酸化。来自JAK3缺陷小鼠的血小板显示STAT1和STAT3的酪氨酸磷酸化减少。与这些数据一致，用JAK3抑制剂WHI-P131预处理人血小板可显著降低组成型活性JAK3的基线酶活性，并消除凝血酶诱导的STAT1和STAT3的酪氨酸磷酸化。在凝血酶刺激后，经WHI-P131处理的血小板未发生指示激活的形状变化，如伪足形成。WHI-P131抑制凝血酶诱导的脱颗粒/5-羟色胺释放以及血小板聚集。在小鼠中可达到高效的血小板抑制血浆浓度的WHI-P131且无毒性。WHI-P131以剂量依赖方式延长小鼠的出血时间，并改善在凝血活酶诱导的全身性且必然致命的血栓栓塞小鼠模型中的无事件生存期。据我们所知，WHI-P131是首个通过抑制JAK3来预防血小板聚集的抗血栓形成药物。
