Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore.
Interdisciplinary Graduate School, NTU Institute for Health Technologies, Nanyang Technological University Singapore, Singapore, Singapore.
Front Immunol. 2021 Feb 24;12:593020. doi: 10.3389/fimmu.2021.593020. eCollection 2021.
Cell-free DNA (cfDNA) is the major structural component of neutrophil extracellular traps (NETs), an innate immune response to infection. Antimicrobial proteins and peptides bound to cfDNA play a critical role in the bactericidal property of NETs. Recent studies have shown that NETs have procoagulant activity, wherein cfDNA triggers thrombin generation through activation of the intrinsic pathway of coagulation. We have recently shown that thrombin binds to NETs and consequently can alter the proteome of NETs. However, the effect of NETs on thrombin is still unknown. In this study, we report that DNA binding leads to thrombin autolysis and generation of multiple thrombin-derived C-terminal peptides (TCPs) Employing a 25-residue prototypic TCP, GKY25 (GKYGFYTHVFRLKKWIQKVIDQFGE), we show that TCPs bind NETs, thus conferring mutual protection against nuclease and protease degradation. Together, our results demonstrate the complex interplay between coagulation, NET formation, and thrombin cleavage and identify a previously undisclosed mechanism for formation of TCPs.
无细胞 DNA（cfDNA）是中性粒细胞胞外诱捕网（NETs）的主要结构成分，是一种针对感染的先天免疫反应。与 cfDNA 结合的抗菌蛋白和肽在 NETs 的杀菌特性中起关键作用。最近的研究表明，NETs 具有促凝活性，其中 cfDNA 通过激活凝血的内在途径触发凝血酶生成。我们最近表明，凝血酶与 NETs 结合，从而可以改变 NETs 的蛋白质组。然而，NETs 对凝血酶的影响尚不清楚。在这项研究中，我们报告说 DNA 结合导致凝血酶自溶，并产生多种凝血酶衍生的 C 末端肽（TCP）。我们使用 25 个残基的原型 TCP GKY25（GKYGFYTHVFRLKKWIQKVIDQFGE）表明，TCP 结合 NETs，从而赋予它们免受核酸酶和蛋白酶降解的相互保护。总之，我们的结果表明了凝血、NET 形成和凝血酶裂解之间的复杂相互作用，并确定了 TCP 形成的先前未披露的机制。
