Trumel C, Si-Tahar M, Balloy V, Chignard M, Chap H, Payrastre B, Plantavid M, Pidard D
Institut Fédératif de Recherche en Immunologie Cellulaire et Moléculaire, INSERM Unité, Hôpital Purpan, Toulouse, France.
FEBS Lett. 2000 Nov 10;484(3):184-8. doi: 10.1016/s0014-5793(00)02152-9.
Neutrophil elastase (NE) upregulates the fibrinogen binding activity of the platelet integrin alpha(IIb)beta(3) through proteolysis of the alpha(IIb) subunit. This cleavage allows a strong potentiation of platelet aggregation induced by low concentrations of cathepsin G (CG), another neutrophil serine proteinase. During this activation process, we observed a strong fibrinogen binding and aggregation-dependent phosphatidylinositol 3,4-bis-phosphate (PtdIns(3,4)P(2)) accumulation. PtdIns(3,4)P(2) has been suggested to play a role in the stabilization of platelet aggregation, possibly through the control of a maintained alpha(IIb)beta(3) integrin activation. Here we show that inhibition of phosphoinositide 3-kinase (PI 3-K) by very low concentrations of wortmannin or LY294002 transformed the irreversible platelet aggregation induced by a combination of NE and low concentrations of CG into a reversible aggregation. However, although inhibition of PI 3-K was very efficient in inducing platelet disaggregation, it did not modify the level of alpha(IIb)beta(3) activation as assessed by binding of an activation-dependent antibody. These results indicate that PI 3-K activity can control the irreversibility of platelet aggregation even under conditions where alpha(IIb)beta(3) integrin remains activated.
中性粒细胞弹性蛋白酶（NE）通过对α（IIb）亚基进行蛋白水解，上调血小板整合素α（IIb）β（3）的纤维蛋白原结合活性。这种切割使得低浓度组织蛋白酶G（CG，另一种中性粒细胞丝氨酸蛋白酶）诱导的血小板聚集得到显著增强。在这个激活过程中，我们观察到强烈的纤维蛋白原结合以及聚集依赖性磷脂酰肌醇3,4 - 二磷酸（PtdIns(3,4)P(2)）积累。有人提出PtdIns(3,4)P(2)可能通过控制α（IIb）β（3）整合素的持续激活，在血小板聚集的稳定中发挥作用。在此我们表明，极低浓度的渥曼青霉素或LY294002对磷酸肌醇3 - 激酶（PI 3 - K）的抑制作用，将由NE和低浓度CG联合诱导的不可逆血小板聚集转变为可逆聚集。然而，尽管抑制PI 3 - K在诱导血小板解聚方面非常有效，但通过激活依赖性抗体结合评估，它并未改变α（IIb）β（3）的激活水平。这些结果表明，即使在α（IIb）β（3）整合素仍保持激活的情况下，PI 3 - K活性也能控制血小板聚集的不可逆性。
