Activated protein C (APC) is a serine protease with anticoagulant and cytoprotective activities. Nonanticoagulant APC mutants show beneficial effects as cytoprotective agents. To study, if such biased APC signaling can be achieved by APC-binding ligands, the aptamer technology has been used. A G-quadruplex-containing aptamer, G-NB3, has been selected that binds to the basic exosite of APC with a K_D of 0.2 nM and shows no binding to APC-related serine proteases or the zymogen protein C. G-NB3 inhibits the inactivation of activated cofactors V and VIII with IC₅₀ values of 11.6 and 13.1 nM, respectively, without inhibiting the cytoprotective and anti-inflammatory functions of APC as tested using a staurosporine-induced apoptosis assay and a vascular barrier protection assay. In addition, G-NB3 prolongs the plasma half-life of APC through inhibition of APC-serine protease inhibitor complex formation. These physicochemical and functional characteristics qualify G-NB3 as a promising therapeutic agent usable to enhance the cytoprotective functions of APC without increasing the risk of APC-related hemorrhage.

中文翻译：

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使用外源抑制适体选择性调节蛋白酶活化蛋白 C。

活化蛋白 C (APC) 是一种丝氨酸蛋白酶，具有抗凝和细胞保护活性。非抗凝 APC 突变体显示出作为细胞保护剂的有益效果。为了研究这种偏向的 APC 信号是否可以通过 APC 结合配体实现，我们使用了适配子技术。已选择包含 G-四链体的适体 G-NB3，它以0.2 nM的 K _D与APC 的碱性外切位点结合，并且不显示与 APC 相关的丝氨酸蛋白酶或酶原蛋白 C 的结合。G-NB3 抑制用 IC ₅₀灭活激活的辅因子 V 和 VIII值分别为 11.6 和 13.1 nM，不抑制 APC 的细胞保护和抗炎功能，如使用星形孢菌素诱导的细胞凋亡测定和血管屏障保护测定所测试。此外，G-NB3 通过抑制 APC-丝氨酸蛋白酶抑制剂复合物的形成，延长了 APC 的血浆半衰期。这些物理化学和功能特性使 G-NB3 成为一种有前途的治疗剂，可用于增强 APC 的细胞保护功能，而不会增加 APC 相关出血的风险。