KChIP-Like Auxiliary Subunits of Kv4 Channels Regulate Excitability of Muscle Cells and Control Male Turning Behavior during Mating in Caenorhabditis elegans
KChIP-Like Auxiliary Subunits of Kv4 Channels Regulate Excitability of Muscle Cells and Control Male Turning Behavior during Mating in Caenorhabditis elegans
复制标题
Kv4 通道的 KChIP 样辅助亚基调节肌肉细胞的兴奋性，并控制秀丽隐杆线虫交配过程中雄性的转向行为。
DOI：
10.1523/jneurosci.3429-14.2015
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发表时间：
2015-02-04
影响因子：
5.3
通讯作者：
Cai, Shi-Qing
中科院分区：
文献类型：
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作者：
Chen, Xin;Ruan, Mei-Yu;Cai, Shi-Qing
电压门控Kv4通道通过传导快速激活-失活电流来控制神经元和心肌细胞的兴奋性。Kv4通道的功能受K+通道相互作用蛋白(KChIP)可溶性辅助亚基的深刻调控。然而，这种调节的体内机制还不完全清楚。在这里，我们鉴定了三个线虫KChIP样蛋白(CeKChIP)，NCS-4，NCS-5和NCS-7。这三种ceKChIP都通过减缓失活动力学和将激活的电压依赖性转移到更超极化的电位来改变线虫Kv4通道直系同源物SHL-1的电特性。在3种ceKChIP基因全部缺失的三条KO虫的培养心肌细胞中，天然SHL-1电流被完全消除。NCS-4的重新表达部分恢复了SHL-1功能通道的表达，而钙结合能力受损的NCS-4突变体NCS-4(EFM)仅增强了SHL-1蛋白的表达，但不能将其从高尔基体转运到细胞膜。此外，翻译记者发现，NCS-4与SHL-1 K+通道在男性斜角肌中组装。NCS-4或shl-1的缺失显著损害了雄性转向，这是一种在交配过程中由斜肌控制的行为。NCS-4缺失突变体的表型可以通过NCS-4的重新表达而得到挽救，但NCS-4(EFM)的重新表达不能挽救NCS-4(EFM)的表型，进一步强调了钙离子与ceKChIPs结合在调节天然SHL-1通道功能中的重要性。综上所述，这些数据揭示了KChIP调节Kv4通道的进化保守机制，并揭示了ceKChIP在调节线虫肌肉细胞兴奋性和动物行为方面的关键作用。
Voltage-gated Kv4 channels control the excitability of neurons and cardiac myocytes by conducting rapidly activating-inactivating currents. The function of Kv4 channels is profoundly modulated by K+ channel interacting protein (KChIP) soluble auxiliary subunits. However, the in vivo mechanism of the modulation is not fully understood. Here, we identified three C. elegans KChIP-like (ceKChIP) proteins, NCS-4, NCS-5, and NCS-7. All three ceKChIPs alter electrical characteristics of SHL-1, a C. elegans Kv4 channel ortholog, currents by slowing down inactivation kinetics and shifting voltage dependence of activation to more hyperpolarizing potentials. Native SHL-1 current is completely abolished in cultured myocytes of Triple KO worms in which all three ceKChIP genes are deleted. Reexpression of NCS-4 partially restored expression of functional SHL-1 channels, whereas NCS-4(efm), a NCS-4 mutant with impaired Ca2+-binding ability, only enhanced expression of SHL-1 proteins, but failed to transport them from the Golgi apparatus to the cell membrane in body wall muscles of Triple KO worms. Moreover, translational reporter revealed that NCS-4 assembles with SHL-1 K+ channels in male diagonal muscles. Deletion of either ncs-4 or shl-1 significantly impairs male turning, a behavior controlled by diagonal muscles during mating. The phenotype of the ncs-4 null mutant could be rescued by reexpression of NCS-4, but not NCS-4(efm), further emphasizing the importance of Ca2+ binding to ceKChIPs in regulating native SHL-1 channel function. Together, these data reveal an evolutionarily conserved mechanism underlying the regulation of Kv4 channels by KChIPs and unravel critical roles of ceKChIPs in regulating muscle cell excitability and animal behavior in C. elegans.