Lipid rafts are necessary for tonic inhibition of cellular tissue factor procoagulant activity
Lipid rafts are necessary for tonic inhibition of cellular tissue factor procoagulant activity
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DOI：
10.1182/blood-2003-07-2399
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发表时间：
2004-04-15
期刊：
影响因子：
20.3
通讯作者：
Tetzloff, TA
中科院分区：
文献类型：
--
作者：
Dietzen, DJ;Page, KL;Tetzloff, TA
总细胞组织因子促凝血活性的一部分在完整细胞中保持掩蔽或“加密”。这种活性的解密部分涉及阴离子磷脂如磷脂酰丝氨酸的细胞外暴露。由于组织因子和磷脂扰码酶活性与脂筏的潜在关联，我们探索了脂筏在调节因子VIIa/组织因子活性中的作用。在HEK 293细胞中，组织因子抗原与脂筏不稳定相关，但用甲基-β-环糊精破坏脂筏导致组织因子促凝血活性的3倍刺激。用甲基-β-环糊精处理与细胞毒性无关，并且不会导致额外组织因子抗原的暴露。用甲基-β-环糊精解密的因子VIIa/组织因子活性在数量上类似于通过使用辛基葡糖苷的裂解浓度获得的活性，但对细胞表面组织因子途径抑制剂和磷脂结合蛋白膜联蛋白V的抑制更敏感。在完全破坏脂筏之前，用甲基-β-环糊精实现组织因子的部分解密，提示磷脂酰丝氨酸的跨双层转运中定位于脂筏的酶的作用。我们的结论是，脂筏所需的细胞组织因子在加密状态的维护。(C)2004年，美国血液学会。
A fraction of total cellular tissue factor procoagulant activity remains masked or "encrypted" in intact cells. Decryption of this activity partly involves the extracellular exposure of anionic phospholipids such as phosphatidylserine. Because of the potential association of tissue factor and phospholipid scramblase activity with lipid rafts, we have explored the role of lipid rafts in regulating factor VIIa/tissue factor activity. In HEK293 cells, tissue factor antigen was not stably associated with lipid rafts, yet disruption of rafts with methyl-beta-cyclodextrin resulted in a 3-fold stimulation of tissue factor procoagulant activity. Treatment with methyl-beta-cyclodextrin was not associated with cytotoxicity and did not result in the exposure of additional tissue factor antigen. Factor VIIa/tissue factor activity decrypted with methyl-beta-cyclodextrin was quantitatively similar to that obtained by using lytic concentrations of octyl glucoside but more sensitive to inhibition by cell surface tissue factor pathway inhibitor and the phospholipid binding protein, annexin V. Partial decryption of tissue factor was achieved with methyl-beta-cyclodextrin prior to complete disruption of lipid rafts, suggesting the role of an enzyme localized to lipid rafts in the transbilayer transport of phosphatidylserine. We conclude that lipid rafts are required for the maintenance of cellular tissue factor in an encrypted state. (C) 2004 by The American Society of Hematology.