Functional tissue factor is entirely cell surface expressed on lipopolysaccharide-stimulated human blood monocytes and a constitutively tissue factor-producing neoplastic cell line.
Functional tissue factor is entirely cell surface expressed on lipopolysaccharide-stimulated human blood monocytes and a constitutively tissue factor-producing neoplastic cell line.
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DOI：
10.1083/jcb.109.1.389
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发表时间：
1989-07
期刊：
影响因子：
--
通讯作者：
Edgington TS
中科院分区：
文献类型：
--
作者：
Drake TA;Ruf W;Morrissey JH;Edgington TS
组织因子(Tf)是一种完整的膜糖蛋白，作为凝血因子VII和VIIa(分别为FVII和FVIIa)的受体和基本辅因子，是凝血酶级联的主要细胞激活剂。以往关于多种细胞类型(溶解或完整状态)的促凝血活性的研究都被不同地解释为TF要么储存在细胞内，要么以隐蔽的形式存在于细胞膜上。利用mAbTf，我们直接研究了Tf在脂多糖刺激的单核细胞和J82膀胱癌细胞中的亚细胞定位和功能活性。用抑制性抗Tf单抗阻断活细胞表面Tf，可使完整细胞和裂解细胞的Tf活性降低90%以上。此外，对FVII和抗Tf单抗与J82细胞结合的定量分析表明，所有表面表达的Tf分子都能够结合配体Fvii。免疫电子显微镜下，Tf仅存在于单核细胞和J82细胞的表膜上，而J82细胞在多泡小体中也含有明显失活的Tf抗原。在完整的细胞表面上，研究了Tf-FVIIa复合物的催化活性，发现相对于细胞裂解产物，Tf-FVIIa的催化活性明显降低。影响转铁蛋白辅因子活性的膜改变可能是在各种细胞环境中调节凝血酶级联启动程度的一种手段。
Tissue factor (TF) is an integral membrane glycoprotein which, as the receptor and essential cofactor for coagulation factors VII and VIIa (FVII and FVIIa, respectively), is the primary cellular activator of the coagulation protease cascade. Previous studies on the procoagulant activity of a variety of cell types (either lysed or in the intact state) have variously been interpreted as showing that TF is either stored intracellularly or is present in a cryptic form in the surface membrane. Using mAbs to TF, we have directly investigated the subcellular localization and functional activity of TF in lipopolysaccharide-stimulated blood monocytes and J82 bladder carcinoma cells. Blocking of surface TF of viable cells with inhibitory anti-TF mAbs abolished greater than 90% of TF activity of the intact cells as well as of lysed cells. Furthermore, quantitative analysis of the binding of FVII and anti-TF mAb to J82 cells demonstrated that all surface-expressed TF molecules were capable of binding the ligand, FVII. By immunoelectron microscopy, TF was present only in the surface membrane of monocytes and J82 cells, although the latter also contained apparently inactive TF antigen in multivesicular bodies. On the intact cell surface the catalytic activity of the TF-FVIIa complex was investigated and found to be markedly less relative to cell lysates. Membrane alterations that affect the cofactor activity of TF may be a means of regulating the extent of initiation of the coagulation protease cascade in various cellular settings.