Département Médicaments et Technologies pour la Santé (DMTS), Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
Int J Mol Sci. 2023 Jan 24;24(3):2330. doi: 10.3390/ijms24032330.
The renin-angiotensin system (RAS) is one of the main regulatory systems of cardiovascular homeostasis. It is mainly composed of angiotensin-converting enzyme (ACE) and angiotensin II receptors AT1 and AT2. ACE and AT1 are targets of choice for the treatment of hypertension, whereas the AT2 receptor is still not exploited due to the lack of knowledge of its physiological properties. Peptide toxins from venoms display multiple biological functions associated with varied chemical and structural properties. If Brazilian viper toxins have been described to inhibit ACE, no animal toxin is known to act on AT1/AT2 receptors. We screened a library of toxins on angiotensin II receptors with a radioligand competition binding assay. Functional characterization of the selected toxin was conducted by measuring second messenger production, G-protein activation and β-arrestin 2 recruitment using bioluminescence resonance energy transfer (BRET) based biosensors. We identified one original toxin, A-CTX-cMila, which is a 7-residues cyclic peptide from with no homology sequence with known angiotensin peptides nor identified toxins, displaying a 100-fold selectivity for AT1 over AT2. This toxin shows a competitive antagonism mode of action on AT1, blocking Gαq, Gαi3, GαoA, β-arrestin 2 pathways and ERK activation. These results describe the first animal toxin active on angiotensin II receptors.
肾素-血管紧张素系统（RAS）是心血管稳态的主要调节系统之一。它主要由血管紧张素转换酶（ACE）和血管紧张素 II 受体 AT1 和 AT2 组成。ACE 和 AT1 是治疗高血压的首选靶点，而 AT2 受体由于对其生理特性缺乏了解而尚未得到利用。毒液中的肽毒素具有多种与不同化学和结构特性相关的生物学功能。虽然巴西毒蛇毒素已被描述为抑制 ACE，但目前还没有已知的动物毒素作用于 AT1/AT2 受体。我们使用放射性配体竞争结合测定法在血管紧张素 II 受体上筛选了毒素文库。通过使用基于生物发光共振能量转移（BRET）的生物传感器测量第二信使产生、G 蛋白激活和β-arrestin 2 募集，对选定的毒素进行功能表征。我们鉴定了一种原始毒素 A-CTX-cMila，它是一种来自 的 7 残基环状肽，与已知的血管紧张素肽或已识别的毒素没有同源序列，对 AT1 的选择性是 AT2 的 100 倍。这种毒素对 AT1 表现出竞争性拮抗作用模式，阻断 Gαq、Gαi3、GαoA、β-arrestin 2 途径和 ERK 激活。这些结果描述了第一种作用于血管紧张素 II 受体的动物毒素。
