Further characterization of the synergistic activation mechanism of cationic channels by M2 and M3 muscarinic receptors in mouse intestinal smooth muscle cells.
Further characterization of the synergistic activation mechanism of cationic channels by M2 and M3 muscarinic receptors in mouse intestinal smooth muscle cells.
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进一步表征小鼠肠平滑肌细胞中 M2 和 M3 毒蕈碱受体对阳离子通道的协同激活机制。
DOI：
10.1152/ajpcell.00277.2019
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
T.
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作者：
Tanahashi;Y.;Katsurada;T.;Inasaki;M.;Uchiyama;M.;Sakamoto;S.;Yamamoto;M.;Matsuyama;T.;Komori;S.;Unno;T.
在小鼠回肠肌细胞中，毒蕈碱受体介导的阳离子电流（mIcat）主要通过M2和M3亚型的协同作用产生，涉及Gi/o型GTP结合蛋白和磷脂酶C（PLC）。我们进一步研究了M2/M3协同途径。Gq/11蛋白抑制剂YM-254890可显著抑制卡巴胆碱诱导的mIcat。然而，Icat不受肝素、calphostin C或白屈菜红碱的影响，这表明Icat激活不涉及磷脂酰肌醇4，5-二磷酸（PIP 2）分解下游的信号分子。M2基因敲除（KO）小鼠由于缺乏M2-Gi/o信号传导而表现出降低的mIcat（约为野生型mIcat的10%）。受损的mIcat对具有刺激Gi/o活性的神经肽Y不敏感。由于缺乏M3-Gq/11信号传导，M3-KO小鼠也显示出降低的mIcat（约为野生型mIcat的6%），并且Icat对具有Gq/11刺激活性的前列腺素F2α不敏感。这些结果表明，Gq/11/PLC水解的PIP 2分解本身在MI活化中的重要性，并且还支持这样的想法，即M2/M3协同途径代表由M2-Gi/o和M3-Gq/11-PLC系统组成的信号复合物，其中两种G蛋白对于该途径是特异的，但在受体偶联中不是普遍的。
In mouse ileal myocytes, muscarinic receptor-mediated cationic current (mIcat) occurs mainly through synergism of M2and M3subtypes involving Gi/o-type GTP-binding proteins and phospholipase C (PLC). We have further studied the M2/M3synergistic pathway. Carbachol-inducedmIcatwas markedly depressed by YM-254890, a Gq/11protein inhibitor. However, themIcatwas unaffected by heparin, calphostin C, or chelerythrine, suggesting thatmIcatactivation does not involve signaling molecules downstream of phosphatidylinositol 4,5-bisphosphate (PIP2) breakdown. M2-knockout (KO) mice displayed a reducedmIcat(~10% of wild-typemIcat) because of the lack of M2-Gi/osignaling. The impairedmIcatwas insensitive to neuropeptide Y possessing a Gi/o-stimulating activity. M3-KO mice also displayed a reducedmIcat(~6% of wild-typemIcat) because of the lack of M3-Gq/11signaling, and themIcatwas insensitive to prostaglandin F2αpossessing a Gq/11-stimulating activity. These results suggest the importance of Gq/11/PLC-hydrolyzed PIP2breakdown itself inmIcatactivation and also support the idea that the M2/M3synergistic pathway represents a signaling complex consisting of M2-Gi/oand M3-Gq/11-PLC systems in which both G proteins are special for this pathway but not general in receptor coupling.