TFPIβ is the GPI-anchored TFPI isoform on human endothelial cells and placental microsomes
TFPIβ is the GPI-anchored TFPI isoform on human endothelial cells and placental microsomes
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DOI：
10.1182/blood-2011-10-388512
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发表时间：
2012-02-02
期刊：
影响因子：
20.3
通讯作者：
Broze, George J., Jr.
中科院分区：
文献类型：
--
作者：
Girard, Thomas J.;Tuley, Elodee;Broze, George J., Jr.
组织因子途径抑制剂（TFPI）产生因子xa依赖的反馈抑制因子VIIa/组织因子诱导凝血。已经确定了TFPI的2个亚型的信息。TFPI α mRNA编码一种具有酸性n端、3个kunitz型蛋白酶抑制剂结构域和一个碱性c端的蛋白，该蛋白已从血浆和培养基中纯化。TFPI β mRNA编码的一种形式是，TFPI α的kuniz -3和c端结构域被另一种天然的c端取代，该c端指导糖基磷脂酰肌醇（GPI）锚点的附着，但TFPI β蛋白是否实际表达尚不清楚。此外，先前的研究表明，磷脂酰肌醇特异性磷脂酶C （PIPLC）处理从细胞中释放的TFPI的主要形式是TFPI α，这意味着它在细胞表面结合到一个单独的gpi锚定的辅助受体上。我们的研究表明，PIPLC处理培养的内皮细胞和胎盘微粒体释放的TFPI形式实际上是TFPI β，基于(1)去糖基化前后在SDS-PAGE上的迁移，(2)缺乏Kunitz-3结构域，(3)它含有GPI锚点。免疫分析表明，虽然内皮细胞分泌TFPI α，但PIPLC处理后从内皮细胞表面和胎盘微粒体释放的TFPI中有95%以上是TFPI β。（血液杂志；2012;119(5):1256-1262）
Tissue factor pathway inhibitor (TFPI) produces factor Xa-dependent feedback inhibition of factor VIIa/tissue factor-induced coagulation. Messages for 2 isoforms of TFPI have been identified. TFPI alpha mRNA encodes a protein with an acidic N-terminus, 3 Kunitz-type protease inhibitor domains and a basic C-terminus that has been purified from plasma and culture media. TFPI beta mRNA encodes a form in which the Kunitz-3 and C-terminal domains of TFPI alpha are replaced with an alter-native C-terminus that directs the attachment of a glycosylphosphatidylinositol (GPI) anchor, but whether TFPI beta protein is actually expressed is not clear. Moreover, previous studies have suggested that the predominant form of TFPI released from cells by phosphatidylinositol-specific phospholipase C (PIPLC) treatment is TFPI alpha, implying it is bound at cell surfaces to a separate GPI-anchored coreceptor. Our studies show that the form of TFPI released by PIPLC treatment of cultured endothelial cells and placental microsomes is actually TFPI beta based on (1) migration on SDS-PAGE before and after deglycosylation, (2) the lack of a Kunitz-3 domain, and (3) it contains a GPI anchor. Immunoassays demonstrate that, although endothelial cells secrete TFPI alpha, greater than 95% of the TFPI released by PIPLC treatment from the surface of endothelial cells and from placental microsomes is TFPI beta. (Blood. 2012;119(5): 1256-1262)