Gajdusek C, Carbon S, Ross R, Nawroth P, Stern D
J Cell Biol. 1986 Aug;103(2):419-28. doi: 10.1083/jcb.103.2.419.
Recent studies have indicated that endothelial cell function includes elaboration of growth factors and regulation of coagulation. In this paper we demonstrate that activated coagulation Factor X (Factor Xa), a product of the coagulation mechanism generated before thrombin, induces enhanced release of endothelial cell mitogens, linking these two functions. Mitogenic activity generated by cultured bovine aortic endothelial cells in response to Factor Xa included platelet-derived growth-factor-like molecules based on a radioreceptor assay. Effective induction of mitogens by Factor Xa required the integrity of the enzyme's active center and the presence of the gamma-carboxyglutamic acid-containing domain of the molecule. Factor Xa-induced release of mitogens from endothelium occurred in serum-free medium and was not altered by hirudin or antibody to Factor V, indicating that it was a direct effect of Factor Xa and was not mediated by thrombin. Elaboration of mitogenic activity required only brief contact between Factor Xa and endothelium, and occurred in a time-dependent manner. Generation of enhanced mitogenic activity in response to Factor Xa was unaffected by the presence of actinomycin D and was not associated with increased hybridization of RNA from treated cells to a v-sis probe. Release of mitogenic activity was dependent on the dose of Factor Xa, being half-maximal at 0.5 nM and reaching a maximum by 5 nM. Radioligand binding studies demonstrated a class of endothelial cell sites half-maximally occupied at a Factor Xa concentration of 0.8 nM. The close correspondence between the parameters of Factor Xa-induced mitogen release and Factor Xa binding suggests these sites may be related. When Factor X was activated on the endothelial cell surface by Factors IXa and VIII, the Factor Xa formed resulted in the induction of enhanced release of mitogenic activity. These data suggest a mechanism by which the coagulation system can locally regulate endothelial cell function and vessel wall biology before thrombin-induced release of growth factors from platelets.
最近的研究表明，内皮细胞功能包括生长因子的分泌和凝血调节。在本文中，我们证明，活化的凝血因子X（因子Xa），一种在凝血酶之前产生的凝血机制产物，可诱导内皮细胞有丝分裂原释放增强，将这两种功能联系起来。基于放射受体分析，培养的牛主动脉内皮细胞对因子Xa产生的有丝分裂活性包括血小板衍生生长因子样分子。因子Xa有效诱导有丝分裂原需要该酶活性中心的完整性以及分子中含γ-羧基谷氨酸结构域的存在。因子Xa诱导内皮细胞释放有丝分裂原发生在无血清培养基中，不受水蛭素或抗因子V抗体的影响，表明这是因子Xa的直接作用，而非由凝血酶介导。有丝分裂活性的分泌仅需要因子Xa与内皮细胞短暂接触，并呈时间依赖性发生。对因子Xa产生的增强有丝分裂活性不受放线菌素D存在的影响，且与处理细胞的RNA与v-sis探针的杂交增加无关。有丝分裂活性的释放取决于因子Xa的剂量，在0.5 nM时达到半数最大效应，在5 nM时达到最大值。放射性配体结合研究表明，一类内皮细胞位点在因子Xa浓度为0.8 nM时被半数占据。因子Xa诱导的有丝分裂原释放参数与因子Xa结合参数之间的密切对应表明这些位点可能相关。当因子X在因子IXa和因子VIII作用下在内皮细胞表面被激活时，形成的因子Xa导致有丝分裂活性释放增强。这些数据提示了一种机制，通过该机制凝血系统可在凝血酶诱导血小板释放生长因子之前局部调节内皮细胞功能和血管壁生物学。
