Llinas Del Torrent Claudia, Raïch Iu, Gonzalez Angel, Lillo Jaume, Casajuana-Martin Nil, Franco Rafael, Pardo Leonardo, Navarro Gemma
Laboratory of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain.
Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, Universitat de Barcelona, Barcelona, Spain.
Br J Pharmacol. 2025 Jul;182(14):3371-3384. doi: 10.1111/bph.16502. Epub 2024 Jul 23.
Allosterism is a regulatory mechanism for GPCRs that can be attained by ligand-binding or protein-protein interactions with another GPCR. We have studied the influence of the dimer interface on the allosteric properties of the A receptor and CB receptor heteromer.
We have evaluated cAMP production, phosphorylation of signal-regulated kinases (pERK1/2), label-free dynamic mass redistribution, β-arrestin 2 recruitment and bimolecular fluorescence complementation assays in the absence and presence of synthetic peptides that disrupt the formation of the heteromer. Molecular dynamic simulations provided converging evidence that the heteromeric interface influences the allosteric properties of the AR-CBR heteromer.
Apo AR blocks agonist-induced signalling of CBR. The disruptive peptides, with the amino acid sequence of transmembrane (TM) 6 of AR or CBR, facilitate CBR activation, suggesting that AR allosterically prevents the outward movement of TM 6 of CBR for G protein binding. Significantly, binding of the selective antagonist SCH 58261 to AR also facilitated agonist-induced activation of CBR.
It is proposed that the AR-CBR heteromer contains distinct dimerization interfaces that govern its functional properties. The molecular interface between protomers of the AR-CBR heteromer interconverted from TM 6 for apo or agonist-bound AR, blocking CBR activation, to mainly the TM 1/7 interface for antagonist-bound AR, facilitating the independent opening of intracellular cavities for G protein binding. These novel results shed light on a different type of allosteric mechanism and extend the repertoire of GPCR heteromer signalling.
This article is part of a themed issue Complexity of GPCR Modulation and Signaling (ERNST). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v182.14/issuetoc.
变构是G蛋白偶联受体（GPCRs）的一种调节机制，可通过配体结合或与另一种GPCR的蛋白质-蛋白质相互作用实现。我们研究了二聚体界面对A受体和CB受体异聚体变构特性的影响。
我们评估了在存在和不存在破坏异聚体形成的合成肽的情况下，环磷酸腺苷（cAMP）的产生量、信号调节激酶（pERK1/2）的磷酸化、无标记动态质量再分布、β-抑制蛋白2的募集以及双分子荧光互补分析。分子动力学模拟提供了一致的证据，表明异聚体界面影响AR-CBR异聚体的变构特性。
无配体的AR阻断激动剂诱导的CBR信号传导。具有AR或CBR跨膜（TM）6氨基酸序列扰动肽促进CBR激活，表明AR变构地阻止CBR的TM 6向外移动以进行G蛋白结合。值得注意的是，选择性拮抗剂SCH 58261与AR的结合也促进了激动剂诱导的CBR激活。
提出AR-CBR异聚体包含不同的二聚化界面，这些界面决定其功能特性。AR-CBR异聚体原聚体之间的分子界面从无配体或激动剂结合的AR的TM 6相互转换，阻断CBR激活，转变为拮抗剂结合的AR主要为TM 1/7界面，促进细胞内腔独立开放以进行G蛋白结合。这些新结果揭示了一种不同类型的变构机制，并扩展了GPCR异聚体信号传导的范围。
本文是主题为“GPCR调节与信号传导的复杂性”（ERNST）特刊的一部分。要查看本节中的其他文章，请访问http://onlinelibrary.wiley.com/doi/10.1111/bph.v182.14/issuetoc。
