Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
Pharmacol Res Perspect. 2024 Dec;12(6):e70038. doi: 10.1002/prp2.70038.
Transient receptor potential melastatin-4 (TRPM4) forms a complex with N-methyl-D-aspartate receptors (NMDARs) that facilitates NMDAR-mediated neurotoxicity. Here we used pharmacological tools to determine how TRPM4 regulates NMDAR signaling. Brophenexin, a compound that binds to TRPM4 at the NMDAR binding interface, protected hippocampal neurons in culture from NMDA-induced death, consistent with published work. Brophenexin (10 μM) reduced NMDA-evoked whole-cell currents recorded at 22°C by 87% ± 14% with intracellular Ca chelated to prevent TRPM4 activation. Brophenexin inhibited NMDA-evoked currents recorded in Na-free solution by 87% ± 13%, suggesting that brophenexin and TRPM4 modulate NMDAR function. Incubating cultures in Mg-free buffer containing tetrodotoxin, 6-cyano-7-nitroquinoxaline-2,3-dione, and bicuculline for 30 min inhibited NMDA-evoked increases in intracellular Ca concentration ([Ca]) recorded at 22°C by 50% ± 18% and prevented inhibition by brophenexin. In the absence of these inhibitors, brophenexin inhibited the NMDA-evoked response by 51% ± 16%. Treatment with the TRPM4 inhibitor 4-chloro-2-(1-naphthyloxyacetamido)benzoic acid (NBA; 10 μM) increased NMDA-evoked Ca influx by 90% ± 15%. Increasing extracellular NaCl to 237 mM, a treatment that activates TRPM4, inhibited the NMDA-evoked increase in [Ca] by a process that occluded the inhibition produced by brophenexin and was prevented by NBA. In recordings performed at 32°C-34°C, brophenexin inhibited the NMDA-evoked [Ca] response by 42% ± 10% but NBA was without effect. These results are consistent with a model in which TRPM4 interacts with NMDARs to potentiate Ca flux through the NMDAR ion channel and thus provides a potential mechanism for the neuroprotection afforded by NMDAR/TRPM4 interface inhibitors such as brophenexin.
瞬时受体电位 melastatin-4 (TRPM4) 与 N-甲基-D-天冬氨酸受体 (NMDAR) 形成复合物，促进 NMDAR 介导的神经毒性。在这里，我们使用药理学工具来确定 TRPM4 如何调节 NMDAR 信号。Brophenexin 是一种与 NMDAR 结合界面的 TRPM4 结合的化合物，可保护培养的海马神经元免受 NMDA 诱导的死亡，这与已发表的工作一致。Brophenexin（10 μM）在 22°C 时将 NMDA 诱导的全细胞电流降低了 87%±14%，其中细胞内 Ca 螯合以防止 TRPM4 激活。Brophenexin 在无 Na 溶液中抑制 NMDA 诱导的电流 87%±13%，表明 brophenexin 和 TRPM4 调节 NMDAR 功能。在含有河豚毒素、6-氰基-7-硝基喹喔啉-2,3-二酮和 BIC 的无镁缓冲液中孵育培养物 30 分钟，可将 22°C 时 NMDA 诱导的细胞内 Ca 浓度 ([Ca]) 增加抑制 50%±18%，并防止 brophenexin 的抑制作用。在没有这些抑制剂的情况下，brophenexin 抑制 NMDA 诱导的反应 51%±16%。用 TRPM4 抑制剂 4-氯-2-(1-萘氧基乙酰胺基)苯甲酸 (NBA；10 μM) 处理可使 NMDA 诱导的 Ca 内流增加 90%±15%。将细胞外 NaCl 增加到 237 mM，这是一种激活 TRPM4 的治疗方法，可通过阻止 brophenexin 产生的抑制作用来抑制 NMDA 诱导的 [Ca]增加，而 NBA 则可预防这种抑制作用。在 32°C-34°C 进行的记录中，brophenexin 抑制 NMDA 诱导的 [Ca]反应 42%±10%，但 NBA 没有作用。这些结果与以下模型一致，即 TRPM4 与 NMDAR 相互作用以增强 NMDAR 离子通道的 Ca 通量，从而为 NMDAR/TRPM4 界面抑制剂（如 brophenexin）提供的神经保护提供了潜在机制。
