Characterization of platelet aminophospholipid externalization reveals fatty acids as molecular determinants that regulate coagulation
Characterization of platelet aminophospholipid externalization reveals fatty acids as molecular determinants that regulate coagulation
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DOI：
10.1073/pnas.1222419110
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发表时间：
2013-04-09
影响因子：
11.1
通讯作者：
O'Donnell, Valerie B.
中科院分区：
文献类型：
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作者：
Clark, Stephen R.;Thomas, Christopher P.;O'Donnell, Valerie B.
氨基磷脂(APL)跨质膜运输是细胞活化、凋亡和衰老的关键事件，是清除垂死细胞和凝血所必需的。目前，外在的磷脂分子种类尚不清楚。利用脂体学方法，我们发现凝血酶、胶原或离子载体激活的人血小板外化两种磷脂酰丝氨酸(PSS)和五种磷脂酰乙醇胺(PES)。4%的细胞PE/PS池(类似于300 ng/2×10(8)细胞，凝血酶)通过钙动员和蛋白酶激活的受体-1和-4外化，48%包含在微粒中。细胞凋亡和能量耗竭(老化)以钙依赖的方式外化相同的APL，所有刺激都外化氧化的磷脂，称为羟基二十碳四烯酸-PES。Scott综合征中突变的跨膜蛋白-16F(TMEM-16F)在凝血酶激活和能量耗竭时需要PE/PS外化，但不需要细胞凋亡。与脂肪酰链较长或较短的APL相比，血小板特异性APL最能支持人体血浆中的组织因子依赖性凝血。这一发现表明，脂肪酸是调节止血的APL的分子决定因素。因此，表征了外源性APL在血小板激活、凋亡和能量耗竭过程中的分子种类，并揭示了它们支持凝血的能力。这一发现对出血性疾病和输血治疗具有治疗意义。该方法也可应用于APL外化的其他细胞事件，包括细胞分裂和囊泡形成。
Aminophospholipid (APL) trafficking across the plasma membrane is a key event in cell activation, apoptosis, and aging and is required for clearance of dying cells and coagulation. Currently the phospholipid molecular species externalized are unknown. Using a lipidomic method, we show that thrombin, collagen, or ionophore-activated human platelets externalize two phosphatidylserines (PSs) and five phosphatidylethanolamines (PEs). Four percent of the total cellular PE/PS pool (similar to 300 ng/2 x 10(8) cells, thrombin), is externalized via calcium mobilization and protease-activated receptors-1 and -4, and 48% is contained in microparticles. Apoptosis and energy depletion (aging) externalized the same APLs in a calcium-dependent manner, and all stimuli externalized oxidized phospholipids, termed hydroxyeicosatetraenoic acid-PEs. Transmembrane protein-16F (TMEM-16F), the protein mutated in Scott syndrome, was required for PE/PS externalization during thrombin activation and energy depletion, but not apoptosis. Platelet-specific APLs optimally supported tissue factor-dependent coagulation in human plasma, vs. APL with longer or shorter fatty acyl chains. This finding demonstrates fatty acids as molecular determinants of APL that regulate hemostasis. Thus, the molecular species of externalized APL during platelet activation, apoptosis, and energy depletion were characterized, and their ability to support coagulation revealed. The findings have therapeutic implications for bleeding disorders and transfusion therapy. The assay could be applied to other cell events characterized by APL externalization, including cell division and vesiculation.