Department of Pharmacology of Chinese Materia Medica, Institution of Chinese Integrative Medicine, Hebei Medical University, Research Unit of Digestive Tract Microecosystem Pharmacology and Toxicology, Chinese Academy of Medical Sciences, Shijiazhuang, Hebei, 050017, China.
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Biochem Biophys Res Commun. 2024 Dec 20;739:150914. doi: 10.1016/j.bbrc.2024.150914. Epub 2024 Oct 29.
N-methyl-d-aspartate receptors (NMDARs), the ligand ion glutamate receptor channels, mediate major excitatory neurotransmission in central nervous system (CNS). They highly express in CNS and involve in multiple physiological processes. Many studies implicated that NMDAR plays a crucial role in number of neurological disorders, including ischemia, dementia, and pain, indicating its potential as a therapeutic target for treatments. Chelerythrine (CHE) is a benzo-phenanthridine alkaloid extracted from Chelidonium majus with many biological activities including anti-inflammatory, anticancer effect, and antidiabetic effect. But the mechanism of CHE is not well understood. The aim of this study was to investigate the effect of CHE on the NMDAR. The results demonstrated that CHE effectively suppressed NMDA-induced currents in primary cultured cortical neurons. To elucidate the underlying mechanism, we expressed NMDARs in HEK293T cells and found that CHE and some of its structural analogues inhibited NMDAR currents and facilitated the desensitization of GluN2B NMDARs. Notably, these effects were independent of protein kinase C activity, suggesting that the effect of CHE on GluN2B-containing NMDAR may occur through a mechanism of directly interaction with NMDAR. Moreover, the inhibitory effect of CHE on GluN2B NMDARs is pH-dependent. Molecular docking prediction in conjunction with mutagenesis analysis revealed that the M3 α-helical segment of the NMDAR in close proximity to the GluN2B Thr647 amino acid plays an important role in CHE inhibition of GluN2B. This study revealed a novel function of CHE and its structural analogues in inhibiting the NMDARs and promoting GluN2B-mediated desensitization by obstructing the receptor at the channel pore region.
N-甲基-D-天冬氨酸受体（NMDARs）是配体离子谷氨酸受体通道，介导中枢神经系统（CNS）中的主要兴奋性神经递质传递。它们在中枢神经系统中高度表达，参与多种生理过程。许多研究表明，NMDAR 在多种神经疾病中发挥着关键作用，包括缺血、痴呆和疼痛，这表明它有可能成为治疗的靶点。白屈菜红碱（CHE）是一种从白屈菜中提取的苯并菲啶生物碱，具有多种生物活性，包括抗炎、抗癌和抗糖尿病作用。但是 CHE 的作用机制尚不清楚。本研究旨在探讨 CHE 对 NMDAR 的影响。结果表明，CHE 能有效抑制原代培养皮质神经元中 NMDA 诱导的电流。为了阐明其潜在机制，我们在 HEK293T 细胞中表达了 NMDAR，发现 CHE 和一些结构类似物抑制了 NMDAR 电流，并促进了 GluN2B NMDAR 的脱敏。值得注意的是，这些作用不依赖于蛋白激酶 C 活性，表明 CHE 对含 GluN2B 的 NMDAR 的作用可能通过与 NMDAR 直接相互作用的机制发生。此外，CHE 对 GluN2B NMDAR 的抑制作用具有 pH 依赖性。分子对接预测结合突变分析表明，NMDAR 的 M3 α-螺旋片段与 GluN2B Thr647 氨基酸密切相关，在 CHE 抑制 GluN2B 中发挥重要作用。本研究揭示了 CHE 及其结构类似物通过阻塞通道孔区域的受体来抑制 NMDAR 并促进 GluN2B 介导的脱敏的新功能。
