Disulfide isomerization switches tissue factor from coagulation to cell signaling
Disulfide isomerization switches tissue factor from coagulation to cell signaling
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DOI：
10.1073/pnas.0606411103
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发表时间：
2006-09-19
影响因子：
11.1
通讯作者：
Ruf, Wolfram
中科院分区：
文献类型：
--
作者：
Ahamed, Jasimuddin;Versteeg, Henri H.;Ruf, Wolfram
细胞表面组织因子（TF）结合丝氨酸蛋白酶因子VIIa以激活凝血，或者通过与炎症和血管生成相关的G蛋白偶联的蛋白酶激活受体2（PAR 2）触发信号传导。这里我们证明了TF（.）VIIa介导的凝血和细胞信号传导涉及不同的TF细胞库。TF的表面可接近的细胞外Cys（186）-Cys（209）二硫键对于凝血是关键的，并且蛋白质二硫键异构酶（PDI）通过靶向该二硫键而使凝血失效。具有未配对Cys（186）的TF突变体（TF C209 A）保留TF-VIIa信号传导活性，并且其对VIIa的亲和力降低，这是在具有组成型TF表达的细胞上传递TF信号的特征。我们进一步表明，PDI抑制TF凝血活性的一氧化氮依赖性途径，连接调节TF血栓形成的氧化应激血管。此外，一种独特的单克隆抗体只识别TF的非凝血性、隐蔽性构象。该抗体抑制TF（.）PAR 2复合物和TF-VIIa信号转导，但它不阻止凝血激活。这些实验描绘了控制TF功能的上游调节机制，并且它们提供了TF-VIIa信号传导可以被特异性抑制而对凝血影响最小的初步证据。
Cell-surface tissue factor (TF) binds the serine protease factor VIIa to activate coagulation or, alternatively, to trigger signaling through the G protein-coupled, protease-activated receptor 2 (PAR2) relevant to inflammation and angiogenesis. Here we demonstrate that TF(.)VIIa-mediated coagulation and cell signaling involve distinct cellular pools of TF. The surf ace-accessible, extracellular Cys(186)-Cys(209) disulfide bond of TF is critical for coagulation, and protein disulfide isomerase (PDI) disables coagulation by targeting this disulfide. A TF mutant (TF C209A) with an unpaired Cys(186) retains TF-VIIa signaling activity, and it has reduced affinity for VIIa, a characteristic of signaling TF on cells with constitutive TF expression. We further show that PDI suppresses TF coagulant activity in a nitric oxide-dependent pathway, linking the regulation of TF thrombogenicity to oxidative stress in the vasculature. Furthermore, a unique monoclonal antibody recognizes only the noncoagulant, cryptic conformation of TF. This antibody inhibits formation of the TF(.)PAR2 complex and TF-VIIa signaling, but it does not prevent coagulation activation. These experiments delineate an upstream regulatory mechanism that controls TF function, and they provide initial evidence that TF-VIIa signaling can be specifically inhibited with minimal effects on coagulation.