Petersen Jacob E, Pavlovskyi Artem, Madsen Jesper J, Schwartz Thue W, Frimurer Thomas M, Olsen Ole H
Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen N, Denmark.
Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA; Center for Global Health and Infectious Diseases Research, Global and Planetary Health, College of Public Health, University of South Florida, Tampa, Florida, USA.
J Biol Chem. 2025 Jun;301(6):108522. doi: 10.1016/j.jbc.2025.108522. Epub 2025 Apr 19.
The tachykinin receptors neurokinin 1 (NK1R) and neurokinin 2 (NK2R) are G protein-coupled receptors that bind preferentially to the natural peptide ligands substance P (SP) and neurokinin A (NKA), respectively. The peptide ligands share a common C-terminal sequence, Phe-X-Gly-Leu-Met-NH, which contributes to their partial cross-reactivity with each other's nonnative receptors. This study examines the impact of truncated tachykinin SP and NKA analogs on signaling activity. SP and NKA were progressively truncated, yielding the shortest versions SP(6-11) and NKA(5-10) with free and acetylated N terminal. A total of 12 SP and 10 NKA analogs were evaluated for activity in bioluminescence resonance energy transfer-based cAMP and IP accumulation assays targeting both NK1R and NK2R, corresponding to G protein and G protein activation, respectively. As previously demonstrated, the first three amino acids are dispensable. When activated by SP analogs, NK1R favors activation of G over G, though this difference diminishes with shorter analogs. In contrast, when NK1R is activated by NKA analogs, the G potency exceeds G potency by nearly an order of magnitude. For NK2R activation by NKA analogs, there are only minor differences between G and G potencies, with a slight preference for higher G potency. The N-terminal charge status plays a key role, leading to significant differences in analog potency. These findings provide valuable insight into how specific receptor-ligand interactions influence downstream G-protein signaling in G protein-coupled receptors, which are highly relevant for therapeutic applications. Finally, the proposed "message-address" model of neuropeptide signaling is assessed for NK1R and NK2R using truncated SP and NKA analogs.
速激肽受体神经激肽1（NK1R）和神经激肽2（NK2R）是G蛋白偶联受体，分别优先结合天然肽配体P物质（SP）和神经激肽A（NKA）。这些肽配体具有共同的C末端序列Phe-X-Gly-Leu-Met-NH，这导致它们与彼此的非天然受体存在部分交叉反应性。本研究考察了截短的速激肽SP和NKA类似物对信号活性的影响。对SP和NKA进行逐步截短，得到了具有游离和乙酰化N末端的最短版本SP(6 - 11)和NKA(5 - 10)。总共评估了12种SP类似物和10种NKA类似物在基于生物发光共振能量转移的cAMP和IP积累测定中的活性，这些测定分别针对NK1R和NK2R，对应于G蛋白和G蛋白的激活。如先前所示，前三个氨基酸是可有可无的。当被SP类似物激活时，NK1R对G的激活偏好超过G，但随着类似物变短，这种差异会减小。相反，当NK1R被NKA类似物激活时，G的效力比G的效力高出近一个数量级。对于NKA类似物激活NK2R，G和G的效力之间只有微小差异，略微偏好更高的G效力。N末端电荷状态起着关键作用，导致类似物效力存在显著差异。这些发现为特定受体 - 配体相互作用如何影响G蛋白偶联受体中的下游G蛋白信号传导提供了有价值的见解，这与治疗应用高度相关。最后，使用截短的SP和NKA类似物对NK1R和NK2R评估了所提出的神经肽信号传导“信息 - 地址”模型。
