Muratspahić Edin, Tomašević Nataša, Nasrollahi-Shirazi Shahrooz, Gattringer Jasmin, Emser Fabiola Susanna, Freissmuth Michael, Gruber Christian W
Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria.
Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria.
J Nat Prod. 2021 Aug 27;84(8):2238-2248. doi: 10.1021/acs.jnatprod.1c00301. Epub 2021 Jul 26.
Cyclotides are plant-derived disulfide-rich peptides comprising a cyclic cystine knot, which confers remarkable stability against thermal, proteolytic, and chemical degradation. They represent an emerging class of G protein-coupled receptor (GPCR) ligands. In this study, utilizing a screening approach of plant extracts and pharmacological analysis we identified cyclotides from to be ligands of the κ-opioid receptor (KOR), an attractive target for developing analgesics with reduced side effects and therapeutics for multiple sclerosis (MS). This prompted us to verify whether [T20K]kalata B1, a cyclotide in clinical development for the treatment of MS, is able to modulate KOR signaling. T20K bound to and fully activated KOR in the low μM range. We then explored the ability of T20K to allosterically modulate KOR. Co-incubation of T20K with KOR ligands resulted in positive allosteric modulation in functional cAMP assays by altering either the efficacy of dynorphin A or the potency and efficacy of U50,488 (a selective KOR agonist), respectively. In addition, T20K increased the basal response upon cotreatment with U50,488. In the bioluminescence resonance energy transfer assay T20K negatively modulated the efficacy of U50,488. This study identifies cyclotides capable of modulating KOR and highlights the potential of plant-derived peptides as an opportunity to develop cyclotide-based KOR modulators.
环肽是一类源自植物的富含二硫键的肽，其包含一个环状胱氨酸结，赋予其对热、蛋白水解和化学降解的显著稳定性。它们是一类新兴的G蛋白偶联受体（GPCR）配体。在本研究中，我们利用植物提取物的筛选方法和药理学分析，从[具体植物名称未给出]中鉴定出环肽是κ-阿片受体（KOR）的配体，KOR是开发副作用较小的镇痛药和治疗多发性硬化症（MS）药物的一个有吸引力的靶点。这促使我们验证正在进行MS治疗临床开发的环肽[T20K]kalata B1是否能够调节KOR信号传导。T20K在低 microM 范围内与KOR结合并完全激活KOR。然后我们探究了T20K变构调节KOR的能力。T20K与KOR配体共同孵育，通过分别改变强啡肽A的效力或U50,488（一种选择性KOR激动剂）的效力和效能，在功能性cAMP测定中导致正变构调节。此外，T20K与U50,488共同处理时增加了基础反应。在生物发光共振能量转移测定中，T20K负向调节U50,488的效力。本研究鉴定出能够调节KOR的环肽，并强调了植物源肽作为开发基于环肽的KOR调节剂的机会的潜力。
