Goschnick Matt W, Lau Lai-Man, Wee Janet L, Liu Yong S, Hogarth P Mark, Robb Lorraine M, Hickey Michael J, Wright Mark D, Jackson Denise E
Burnet Institute/Austin Research Institute, Studley Road, Heidelberg, Victoria 3084, Australia.
Blood. 2006 Sep 15;108(6):1911-8. doi: 10.1182/blood-2006-02-004267. Epub 2006 May 23.
We investigated the role of the hematopoietic-specific tetraspanin superfamily member, TSSC6, in platelet function using wild-type mice and TSSC6-deficient mice. TSSC6 is expressed on the surface of murine platelets and is up-regulated by thrombin stimulation, indicating an intracellular pool of TSSC6. Immunoprecipitation/Western blot studies reveal a constitutive physical association of TSSC6 with the integrin alpha(IIb)beta(3) complex under strong detergent conditions. In vivo evaluation of hemostasis by tail bleeding revealed increased bleeding time, volume of blood lost, and evidence of tail rebleeds in TSSC6 null mice, indicating unstable hemostasis. Using ex vivo techniques, we showed that TSSC6-deficient platelets exhibited impaired kinetics of clot retraction, platelet aggregation at lower doses of PAR-4, and collagen and platelet spreading on fibrinogen in the presence of normal integrin alpha(IIb)beta(3) expression. TSSC6-deficient platelets showed normal alpha granule secretion, normal "inside-out" integrin alpha(IIb)beta(3) signaling (fluorescein isothiocyanate [FITC]-fibrinogen and JON/A binding), and normal platelet adhesion on fibrinogen. Furthermore, we show that absence of platelet TSSC6 affects the secondary stability of arterial thrombi in vivo upon vascular injury. These data demonstrate that TSSC6 appears to regulate integrin alpha(IIb)beta(3) "outside-in" signaling events in platelets and is necessary for stability of arterial thrombi in vivo.
我们使用野生型小鼠和TSSC6基因敲除小鼠，研究了造血特异性四跨膜蛋白超家族成员TSSC6在血小板功能中的作用。TSSC6在小鼠血小板表面表达，并在凝血酶刺激下上调，提示存在细胞内TSSC6池。免疫沉淀/蛋白质印迹研究显示，在强去污剂条件下，TSSC6与整合素α（IIb）β（3）复合物存在组成性物理关联。通过尾部出血对止血进行的体内评估显示，TSSC6基因敲除小鼠的出血时间延长、失血量增加且有尾部再次出血的迹象，表明止血不稳定。使用体外技术，我们发现TSSC6基因敲除的血小板在正常整合素α（IIb）β（3）表达情况下，表现出凝块回缩动力学受损、低剂量PAR - 4诱导的血小板聚集受损以及在纤维蛋白原上的胶原和血小板铺展受损。TSSC6基因敲除的血小板显示α颗粒分泌正常、“由内向外”整合素α（IIb）β（3）信号正常（异硫氰酸荧光素[FITC] - 纤维蛋白原和JON/A结合）以及在纤维蛋白原上的血小板黏附正常。此外，我们发现血小板TSSC6的缺失会影响体内血管损伤后动脉血栓的二级稳定性。这些数据表明，TSSC6似乎在血小板中调节整合素α（IIb）β（3）的“由外向内”信号事件，并且是体内动脉血栓稳定性所必需的。
