Distinct roles of NR2A and NR2B cytoplasmic tails in long-term potentiation.
Distinct roles of NR2A and NR2B cytoplasmic tails in long-term potentiation.
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DOI：
10.1523/jneurosci.4022-09.2010
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发表时间：
2010-02-17
期刊：
影响因子：
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通讯作者：
Sheng M
中科院分区：
文献类型：
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作者：
Foster KA;McLaughlin N;Edbauer D;Phillips M;Bolton A;Constantine-Paton M;Sheng M
NMDA受体（NMDARs）是活动依赖性突触可塑性的关键介质，但含有NR 2A和NR 2B的NMDARs的不同作用一直存在争议。在这里，我们研究NR 2A和NR 2B在LTP中的作用，在器官型海马切片培养使用RNAi和过表达，以补充药理学方法。在年轻的切片中，当NR 2B是表达的主要亚基时，LTP被NR 2B选择性拮抗剂Ro 25 -6981阻断。随着脑片成熟，NR 2A表达增加，NR 2B受体的激活不再是LTP诱导所必需的。然而，通过RNAi敲低NR 2B，LTP被阻断，并且通过共表达RNAi抗性NR 2B（NR 2B *）cDNA来拯救。有趣的是，其中C-末端胞质尾被NR 2A的C-末端胞质尾替换的嵌合NR 2B亚基未能拯救LTP，而反向嵌合体，NR 2A通道与NR 2B尾，能够恢复LTP。因此，在NR 2B-NMDAR的通道活性对于LTP不需要的年龄，具有完整胞质尾区的NR 2B的表达对于LTP诱导是需要的。野生型NR 2A的过表达未能挽救用NR 2B-RNAi构建体转染的神经元中的LTP，尽管恢复NMDA-EPSC振幅至与NR 2B * 相似的水平。令人惊讶的是，缺乏其整个C-末端胞质尾的NR 2A构建体恢复了其恢复LTP的能力。总之，这些数据表明，NR 2B亚基起着关键作用的LTP，大概是通过招募相关分子的LTP通过其胞质尾。相比之下，NR 2A不是LTP所必需的，其胞质尾似乎携带LTP的抑制因子。
NMDA receptors (NMDARs) are critical mediators of activity-dependent synaptic plasticity, but the differential roles of NR2A- versus NR2B-containing NMDARs have been controversial. Here, we investigate the roles of NR2A and NR2B in LTP in organotypic hippocampal slice cultures using RNAi and overexpression, to complement pharmacological approaches. In young slices, when NR2B is the predominant subunit expressed, LTP is blocked by the NR2B-selective antagonist Ro25-6981. As slices mature, and NR2A expression rises, activation of NR2B receptors became no longer necessary for LTP induction. LTP was blocked, however, by RNAi knockdown of NR2B, and this was rescued by coexpression of an RNAi-resistant NR2B (NR2B*) cDNA. Interestingly, a chimeric NR2B subunit in which the C-terminal cytoplasmic tail was replaced by that of NR2A failed to rescue LTP while the reverse chimera, NR2A channel with NR2B tail, was able to restore LTP. Thus expression of NR2B with its intact cytoplasmic tail is required for LTP induction, at an age when channel activity of NR2B-NMDARs is not required for LTP. Overexpression of wildtype NR2A failed to rescue LTP in neurons transfected with NR2B-RNAi construct, despite restoring NMDA-EPSC amplitude to a similar level as NR2B*. Surprisingly, an NR2A construct lacking its entire C-terminal cytoplasmic tail regained its ability to restore LTP. Together these data suggest that the NR2B subunit plays a critical role for LTP, presumably by recruiting relevant molecules important for LTP via its cytoplasmic tail. By contrast, NR2A is not essential for LTP and its cytoplasmic tail seems to carry inhibitory factors for LTP.