Tissue factor activation: is disulfide bond switching a regulatory mechanism?
Tissue factor activation: is disulfide bond switching a regulatory mechanism?
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DOI：
10.1182/blood-2007-07-101469
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发表时间：
2007-12-01
期刊：
影响因子：
20.3
通讯作者：
Rao, L. Vijaya Mohan
中科院分区：
文献类型：
--
作者：
Pendurthi, Usha R.;Ghosh, Samit;Rao, L. Vijaya Mohan
细胞表面的大部分组织因子（TF）以隐蔽形式存在（即凝血功能失活），但保留其在细胞信号传导中的功能。最近的研究表明，隐藏的TF含有未配对的半胱氨酸巯基，激活涉及二硫键Cys 186-Cys 209的形成，蛋白质二硫键异构酶（PDI）通过靶向该二硫键调节TF凝血和信号传导活性。本研究旨在探讨这一新概念的有效性。虽然治疗MDA 231肿瘤细胞，成纤维细胞，和刺激的内皮细胞与氧化剂氯化汞显着增加细胞表面TF凝血活性，增加与增加阴离子磷脂在细胞表面。结合阴离子磷脂的膜联蛋白V减弱了TF凝血活性的增加。值得注意的是，用还原剂处理细胞也增加了细胞表面TF活性。没有证据表明在细胞表面可检测到PDI的表达或TF与PDI的相关性。此外，基因沉默降低PDI对TF凝血剂或细胞信号传导功能没有影响。总体而言，目前的数据破坏了最近提出的假设，即PDI介导的二硫键交换在调节TF促凝血和细胞信号传导功能中起作用。
A majority of tissue factor (TF) on cell surfaces exists in a cryptic form (ie, coagulation function inactive) but retains its functionality in cell signaling. Recent studies have suggested that cryptic TF contains unpaired cysteine thiols and that activation involves the formation of the disulfide bond Cys186-Cys 209 and that protein disulfide isomerase (PDI) regulates TF coagulant and signaling activities by targeting this disulfide bond. This study was carried out to investigate the validity of this novel concept. Although treatment of MDA 231 tumor cells, fibroblasts, and stimulated endothelial cells with the oxidizing agent HgCl2 markedly increased the cell-surface TF coagulant activity, the increase is associated with increased anionic phospholipids at the cell surface. Annexin V, which binds to anionic phospholipids, attenuated the increased TF coagulant activity. It is noteworthy that treatment of cells with reducing agents also increased the cell surface TF activity. No evidence was found for either detectable expression of PDI at the cell surface or association of TF with PDI. Furthermore, reduction of PDI with the gene silencing had no effect on either TF coagulant or cell signaling functions. Overall, the present data undermine the recently proposed hypothesis that PDI-mediated disulfide exchange plays a role in regulating TF procoagulant and cell signaling functions.