Activation of galanin receptor 2 stimulates large conductance Ca2+-dependent K+ (BK) channels through the IP3 pathway in human embryonic kidney (HEK293) cells
Activation of galanin receptor 2 stimulates large conductance Ca2+-dependent K+ (BK) channels through the IP3 pathway in human embryonic kidney (HEK293) cells
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甘丙肽受体 2 的激活通过人胚肾 (HEK293) 细胞中的 IP3 途径刺激大电导 Ca2 依赖性 K (BK) 通道
DOI：
10.1016/j.bbrc.2014.02.110
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发表时间：
2014-03-28
影响因子：
3.1
通讯作者：
Xu, Zhi-Qing David
中科院分区：
文献类型：
--
作者：
Pan, Na Clara;Bai, Yun-Fei;Xu, Zhi-Qing David
大电导钙激活钾(BK)通道广泛分布于脑内，在神经元中起细胞内钙感受器的作用。它们在控制钙离子流量和钙依赖过程中起着重要的反馈作用，包括神经递质的释放和细胞的兴奋性。本研究通过测定共表达GalR2和BKα亚基的人胚胎肾(HEK293)细胞的全细胞电流和单通道活动，研究神经肽甘丙肽对BK通道的影响。甘丙肽以浓度依赖和PTX非依赖性的方式增强BK通道电流，其ED50值为71.8+/-16.9 nM。这种激活是由GalR2介导的，因为它的激动剂AR-M1896模仿Galanin的作用，并且Galanin不促进共表达BK和GalR1或GalR3的细胞中的BK电流。甘丙素诱导的BK电流在无钙溶液替代后持续存在，提示细胞外钙离子不是必需的。用慢钙缓冲液EGTA或快钙缓冲液BAPTA螯合细胞内钙离子，均可阻断甘丙素介导的BK通道激活，提示细胞内钙离子的重要作用。肌浆网/内质网(SR/ER)钙外流的作用被thapsigargin所证实，thapsigargin是一种不可逆转的耗竭肌浆网/内质网(SR/ER)钙离子的抑制剂。此外，肌醇-1，4，5-三磷酸受体(IP3R)被认为是导致细胞内钙激活BK通道增加的中介。综上所述，GalR2的激活导致细胞内钙的升高是由于内质网钙离子通过IP3R外流，进而开放BK通道。(C)2014 Elsevier Inc.保留所有权利。
The large conductance Ca2+-activated K+ (BK) channels are widely distributed in the brain, and act as intracellular calcium sensors in neurons. They play an important feedback role in controlling Ca2+ flux and Ca2+-dependent processes, including neurotransmitter release and cellular excitability. In this study, the effects of the neuropeptide galanin on BK channels were examined by determining the whole-cell currents and single-channel activities in human embryonic kidney (HEK293) cells co-expressing GalR2 and the BK alpha subunit. Galanin enhanced the currents of BK channels, in a concentration-dependent and PTX-independent manner, with an ED50 value of 71.8 +/- 16.9 nM. This activation was mediated by GalR2, since its agonist AR-M1896 mimicked the effect of galanin, and since galanin did not facilitate BK currents in cells co-expressing cDNAs of BK and GalR1 or GalR3. The galanin-induced BK current persisted after replacement with Ca2+-free solution, suggesting that extracellular Ca2+ is not essential. Chelating intracellular Ca2+ by either the slow Ca2+ buffer EGTA or the fast Ca2+ buffer BAPTA abolished galanin-mediated activation of BK channels, indicating the important role of intracellular Ca2+. The role of Ca2+ efflux from the sarcoplasmic reticulum/endoplasmic reticulum (SR/ER) was confirmed by application of thapsigargin, an irreversible inhibitor that depletes Ca2+ from SR/ER. Moreover, the inositol-1,4,5-triphosphate receptor (IP3R) was identified as the mediator responsible for increased intracellular Ca2+ activating BK channels. Taken together, activation of GalR2 leads to elevation of intracellular Ca2+ is due to Ca2+ efflux from ER through IP3R sequentially opening BK channels. (c) 2014 Elsevier Inc. All rights reserved.