Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru, Karnataka, India.
Vijayashree Diagnostics, Specialized Coagulation Lab, Bengaluru, India.
Biochim Biophys Acta Mol Cell Res. 2021 Mar;1868(3):118925. doi: 10.1016/j.bbamcr.2020.118925. Epub 2020 Dec 14.
Plant latex proteases (PLPs) are pharmacologically essential and are integral components of traditional medicine in the management of bleeding wounds. PLPs are known to promote blood coagulation and stop bleeding by interfering at various stages of hemostasis. There are a handful of scientific reports on thrombin-like enzymes characterized from plant latices. However, the role of plant latex thrombin-like enzymes in platelet aggregation is not well known. In the present study, we attempted to purify and characterize thrombin-like protease responsible for platelet aggregation. Among tested plant latices, Euphorbia genus latex protease fractions (LPFs) induced platelet aggregation. In Euphorbia genus, E. antiquorum LPF (EaLPF) strongly induced platelet aggregation and attenuated bleeding in mice. The purified thrombin-like serine protease, antiquorin (Aqn) is a glycoprotein with platelet aggregating activities that interfere in intrinsic and common pathways of blood coagulation cascade and alleviates bleeding and enhanced excision wound healing in mice. In continuation, the pharmacological inhibitor of PAR1 inhibited Aqn-induced phosphorylation of cPLA, Akt, and P38 in human platelets. Moreover, Aqn-induced platelet aggregation was inhibited by pharmacological inhibitors of PAR1, PI3K, and P38. These data indicate that PAR1-Akt/P38 signaling pathways are involved in Aqn-induced platelet aggregation. The findings of the present study may open up a new avenue for exploiting Aqn in the treatment of bleeding wounds.
植物乳胶蛋白酶（PLPs）在药理学上是必不可少的，是传统医学中处理出血伤口的重要组成部分。PLPs 已知通过干扰止血的各个阶段来促进血液凝固和止血。有一些关于从植物乳胶中提取的类凝血酶酶的科学报道。然而，植物乳胶类凝血酶酶在血小板聚集中的作用尚不清楚。在本研究中，我们试图纯化和表征负责血小板聚集的类凝血酶蛋白酶。在测试的植物乳胶中，大戟属乳胶蛋白酶（LPF）诱导血小板聚集。在大戟属植物中，E. antiquorum LPF（EaLPF）强烈诱导血小板聚集，并减轻小鼠出血。纯化的类凝血酶丝氨酸蛋白酶 antiquorin（Aqn）是一种具有血小板聚集活性的糖蛋白，可干扰血液凝固级联的内在和共同途径，并减轻出血和增强小鼠的切除伤口愈合。此外，PAR1 的药理学抑制剂抑制了 Aqn 诱导的人血小板中 cPLA、Akt 和 P38 的磷酸化。此外，PAR1、PI3K 和 P38 的药理学抑制剂抑制了 Aqn 诱导的血小板聚集。这些数据表明，PAR1-Akt/P38 信号通路参与了 Aqn 诱导的血小板聚集。本研究的结果可能为利用 Aqn 治疗出血伤口开辟新途径。
