Jackson C W, Hutson N K, Steward S A, Saito N, Cramer E M
Department of Hematology/Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101.
J Clin Invest. 1991 Jun;87(6):1985-91. doi: 10.1172/JCI115226.
Rats of the Wistar Furth (WF) strain have hereditary macrothrombocytopenia (large mean platelet volume [MPV] with increased platelet size heterogeneity and reduced platelet count). Ultrastructural studies suggest that this anomaly results from erratic subdivision of megakaryocyte cytoplasm into platelets. In this study, we have examined protein profiles of platelets of WF rats for biochemical abnormalities associated with this anomaly. Marked decreases in protein bands with an Mr of 185, 57, 53, 16, 13, and 8 kd were observed in one-dimensional reduced SDS-PAGE gels in WF platelets compared with platelets of Wistar, Long Evans, and Sprague-Dawley rats. These proteins were released into the supernatant when washed platelets were treated with thrombin suggesting that they were alpha-granule proteins. These abnormalities were not present in offspring of crosses between Wistar Furth and Wistar rats; however, they were present in platelets of offspring with large MPV derived from backcrosses of (WF X Wistar) F1 males to WF females, but not in backcross offspring with normal platelet size. Immunoblotting confirmed decreased levels of thrombospondin, fibrinogen, and platelet factor 4 in WF platelets. Electron microscopic examination revealed that platelet alpha granules were usually smaller in Wistar Furth than in Wistar rats. In addition, immunogold electron microscopy demonstrated that the surface connected canalicular system of the large Wistar Furth platelets, contained dense material composed of alpha-granule proteins, not present in Wistar platelets. From these results, we conclude that the Wistar Furth rat platelet phenotype of large mean platelet volume and decreased levels of alpha-granule proteins represents an animal model resembling gray platelet syndrome. The autosomal recessive pattern of inheritance of the large MPV phenotype and platelet alpha-granule protein deficiencies suggests that a component common to both formation of platelet alpha granules, and subdivision of megakaryocyte cytoplasm into platelets, is quantitatively or qualitatively abnormal in Wistar Furth rat megakaryocytes and platelets.
Wistar Furth（WF）品系大鼠患有遗传性大血小板减少症（平均血小板体积大[MPV]，血小板大小异质性增加且血小板计数减少）。超微结构研究表明，这种异常是由于巨核细胞胞质不规则地细分为血小板所致。在本研究中，我们检查了WF大鼠血小板的蛋白质谱，以寻找与这种异常相关的生化异常。与Wistar、Long Evans和Sprague-Dawley大鼠的血小板相比，在WF血小板的一维还原SDS-PAGE凝胶中观察到Mr为185、57、53、16、13和8 kd的蛋白条带明显减少。当洗涤后的血小板用凝血酶处理时，这些蛋白质释放到上清液中，表明它们是α-颗粒蛋白。Wistar Furth与Wistar大鼠杂交后代中不存在这些异常；然而，在（WF×Wistar）F1雄性与WF雌性回交产生的MPV大的后代血小板中存在这些异常，但在血小板大小正常的回交后代中不存在。免疫印迹证实WF血小板中血小板反应蛋白、纤维蛋白原和血小板因子4的水平降低。电子显微镜检查显示，Wistar Furth大鼠的血小板α-颗粒通常比Wistar大鼠的小。此外，免疫金电子显微镜显示，大的Wistar Furth血小板的表面连接小管系统含有由α-颗粒蛋白组成的致密物质，而Wistar血小板中不存在。根据这些结果，我们得出结论，Wistar Furth大鼠血小板平均体积大且α-颗粒蛋白水平降低的表型代表一种类似于灰色血小板综合征的动物模型。大MPV表型和血小板α-颗粒蛋白缺乏的常染色体隐性遗传模式表明，在Wistar Furth大鼠的巨核细胞和血小板中，血小板α-颗粒形成和巨核细胞胞质细分为血小板过程中共同的一个成分在数量或质量上是异常的。
