A voltage-driven switch for ion-independent signaling by ether-a-go-go K+ channels
A voltage-driven switch for ion-independent signaling by ether-a-go-go K+ channels
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DOI：
10.1073/pnas.0505909103
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发表时间：
2006-02-21
影响因子：
11.1
通讯作者：
Wilson, GF
中科院分区：
文献类型：
--
作者：
Hegle, AP;Marble, DD;Wilson, GF
电压门控通道通过调节离子流维持细胞静息电位并产生神经元动作电位。在这里，我们表明，Ether-a-go-go（EAG）K+通道也调节细胞内信号转导途径的机制，是独立的离子通量，并取决于电压传感器的位置。细胞内信号的调节最初是从增殖的变化推断的。具体而言，用野生型或非传导性（F456 A）eag转染NIH 3 T3成纤维细胞或C2 C12成肌细胞导致细胞密度和BrdUrd掺入显著增加，超过载体和Shaker转染的对照。EAG的作用不依赖于血清，不受细胞外钙变化的影响。p38丝裂原活化蛋白（MAP）激酶的抑制剂，而不是p44/42 MAP激酶（细胞外信号调节激酶），阻断了无血清培养基中的非传导性EAG诱导的增殖，EAG增加了p38 MAP激酶的活性。重要的是，增加开放状态下通道比例的突变抑制了EAG诱导的增殖，这种效应不能用EAG表面表达的变化来解释。这些结果表明，通道构象是一个开关的信号转导活性的EAG，并建议一种替代机制，连接通道活性的细胞内信使的活性，以前一直只归因于调节钙离子内流的通道的作用。
Voltage-gated channels maintain cellular resting potentials and generate neuronal action potentials by regulating ion flux. Here, we show that Ether-a-go-go (EAG) K+ channels also regulate intracellular signaling pathways by a mechanism that is independent of ion flux and depends on the position of the voltage sensor. Regulation of intracellular signaling was initially inferred from changes in proliferation. Specifically, transfection of NIH 3T3 fibroblasts or C2C12 myoblasts with either wild-type or nonconducting (F456A) eag resulted in dramatic increases in cell density and BrdUrd incorporation over vector- and Shaker-transfected controls. The effect of EAG was independent of serum and unaffected by changes in extracellular calcium. Inhibitors of p38 mitogen-activated protein (MAP) kinases, but not p44/42 MAP kinases (extracellular signal-regulated kinases), blocked the proliferation induced by nonconducting EAG in serum-free media, and EAG increased p38 MAP kinase activity. Importantly, mutations that increased the proportion of channels in the open state inhibited EAG-induced proliferation, and this effect could not be explained by changes in the surface expression of EAG. These results indicate that channel conformation is a switch for the signaling activity of EAG and suggest an alternative mechanism for linking channel activity to the activity of intracellular messengers, a role that previously has been ascribed only to channels that regulate calcium influx.