Sicard Antoine, Tian Meilin, Mostefai Zakaria, Shi Sophie, Cardoso Cécile, Zamith Joseph, McCort-Tranchepain Isabelle, Charrier Cécile, Paoletti Pierre, Mony Laetitia
Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, 46 rue d'Ulm, 75005, Paris, France.
Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China.
EMBO J. 2025 Jul 8. doi: 10.1038/s44318-025-00498-x.
Neurotransmitter receptors are critical for neuronal communication. They often form large multimeric complexes that differ in their subunit composition, distribution, and signaling properties. N-methyl-D-aspartate receptors (NMDARs), a class of glutamate-gated ion channels with essential roles in brain development and plasticity, co-exist as multiple subtypes, with GluN2A diheteromers, GluN2B diheteromers, and GluN2A/GluN2B triheteromers prevailing in the adult forebrain. Studying individual subtypes in native tissues with subunit stoichiometry resolution remains challenging, and the relative abundance and subcellular distribution of these subtypes remain controversial. Here we develop and use the photochemical tool Opto2B for specific and reversible modulation of GluN2B diheteromers, while leaving other receptor subtypes (in particular GluN2A/GluN2B triheteromers) unaffected. Using Opto2B, we characterize the differential contribution of GluN2B diheteromers to synaptic and extrasynaptic NMDAR pools during mouse development. Our results suggest that GluN2A receptors predominate in both pools in adult hippocampal CA1 pyramidal cells, with no preferential contribution of GluN2B diheteromers to extrasynaptic currents, challenging the common view that GluN2A and GluN2B NMDARs segregate in synaptic and extrasynaptic compartments, respectively. Our study addresses long-standing questions on extrasynaptic NMDARs and paves the way for interrogating NMDAR signaling diversity with unprecedented molecular and spatio-temporal resolution.
神经递质受体对于神经元通讯至关重要。它们常常形成大型多聚体复合物，这些复合物在亚基组成、分布和信号特性方面存在差异。N - 甲基 - D - 天冬氨酸受体（NMDARs）是一类谷氨酸门控离子通道，在大脑发育和可塑性中发挥着重要作用，以多种亚型共存，其中GluN2A二聚体、GluN2B二聚体以及GluN2A/GluN2B三聚体在成年前脑占主导地位。在天然组织中以亚基化学计量分辨率研究单个亚型仍然具有挑战性，并且这些亚型的相对丰度和亚细胞分布仍存在争议。在此，我们开发并使用光化学工具Opto2B对GluN2B二聚体进行特异性和可逆性调节，同时不影响其他受体亚型（特别是GluN2A/GluN2B三聚体）。利用Opto2B，我们表征了GluN2B二聚体在小鼠发育过程中对突触和突触外NMDAR库的不同贡献。我们的结果表明，在成年海马CA1锥体细胞的两个库中，GluN2A受体均占主导地位，GluN2B二聚体对突触外电流没有优先贡献，这对普遍认为GluN2A和GluN2B NMDARs分别在突触和突触外区室中分离的观点提出了挑战。我们的研究解决了关于突触外NMDARs的长期问题，并为以前所未有的分子和时空分辨率探究NMDAR信号多样性铺平了道路。
