Modulation of Nav1.7 and Nav1.8 peripheral nerve sodium channels by protein kinase A and protein kinase C
Modulation of Nav1.7 and Nav1.8 peripheral nerve sodium channels by protein kinase A and protein kinase C
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DOI：
10.1152/jn.00676.2003
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发表时间：
2004-04-01
影响因子：
2.5
通讯作者：
Chahine, M
中科院分区：
文献类型：
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作者：
Vijayaragavan, K;Boutjdir, M;Chahine, M
电压门控钠离子通道(VGSC)是一种跨膜蛋白，在神经元兴奋性的动作电位的启动和传播中起着至关重要的作用。由于神经元表达Na+通道亚型和蛋白激酶C(PKC)同工酶的混合物，哪种通道的性质由哪种PKC同工酶调节尚不清楚。我们用双电极电压钳方法证明了在非洲爪哇卵母细胞中表达的DRG VGSC Na-v1.7(TTX敏感)和Na-v1.8(TTX抗性)分别受到蛋白激酶A(PKA)和PKC同工酶的差异调节。激活PKA后，Na-v1.8电流呈剂量依赖性增强，而Na-v1.7电流呈剂量依赖性衰减。PKA引起的峰电流增加(Na-v 1.8)和降低(Na-v 1.7)与电压依赖性激活或失活的变化无关。氯喹可抑制PKA介导的Na-v1.8电流幅度的增加，提示细胞转运可能参与了Na-v1.8电流幅度的变化。PKC激动剂佛波醇12-肉豆蔻酸盐、13-乙酸酯(PMA)和佛波醇12，13-二丁酸酯对Na-v 1.7和Na-v 1.8电流有剂量依赖性的抑制作用。PMA使Na-v 1.7和Na v 1.8通道的稳态激活分别向去极化方向移动6.5 mV和14 mV。使用PKC同工酶特异的多肽激活剂和抑制剂，确定单个PKC同工酶在调节Na-v1.7和Na-v1.8中的作用。PMA引起的Na-v1.8峰电流的降低可被特异性的epsilonPKC同工酶多肽拮抗剂阻断，而PMA对Na v1.7的作用可被epsilonPKC和BetaIIPKC多肽抑制剂所阻断。结果表明，Na-v 1.7和Na v 1.8分别受PKA和PKC的不同调控。这是首次报道了epsilonPKC和BetaIIPKC在Na-v 1.7和Na-v 1.8 Na+通道调节中的作用。鉴定介导Na+通道调节的蛋白激酶C同工酶(S)对于理解正常和病理条件下神经元离子通道调节的分子机制是必不可少的。
Voltage-gated Na+ channels (VGSC) are transmembrane proteins that are essential for the initiation and propagation of action potentials in neuronal excitability. Because neurons express a mixture of Na+ channel isoforms and protein kinase C (PKC) isozymes, the nature of which channel is being regulated by which PKC isozyme is not known. We showed that DRG VGSC Na-v 1.7 (TTX-sensitive) and Na-v 1.8 (TTX-resistant), expressed in Xenopus oocytes were differentially regulated by protein kinase A (PKA) and PKC isozymes using the two-electrode voltage-clamp method. PKA activation resulted in a dose-dependent potentiation of Na-v 1.8 currents and an attenuation of Na-v 1.7 currents. PKA-induced increases ( Na-v 1.8) and decreases (Na-v 1.7) in peak currents were not associated with shifts in voltage-dependent activation or inactivation. The PKA-mediated increase in Na-v 1.8 current amplitude was prevented by chloroquine, suggesting that cell trafficking may contribute to the changes in Na-v 1.8 current amplitudes. A dose-dependent decrease in Na-v 1.7 and Na-v 1.8 currents was observed with the PKC activators phorbol 12-myristate, 13-acetate (PMA) and phorbol 12,13-dibutyrate. PMA induced shifts in the steady-state activation of Na-v 1.7 and Na v 1.8 channels by 6.5 and 14 mV, respectively, in the depolarizing direction. The role of individual PKC isozymes in the regulation of Na-v 1.7 and Na-v 1.8 was determined using PKC-isozyme-specific peptide activators and inhibitors. The decrease in the Na-v 1.8 peak current induced by PMA was prevented by a specific epsilonPKC isozyme peptide antagonist, whereas the PMA effect on Na v 1.7 was prevented by epsilonPKC and betaIIPKC peptide inhibitors. The data showed that Na-v 1.7 and Na v 1.8 were differentially modulated by PKA and PKC. This is the first report demonstrating a functional role for epsilonPKC and betaIIPKC in the regulation of Na-v 1.7 and Na-v 1.8 Na+ channels. Identification of the particular PKC isozymes(s) that mediate the regulation of Na+ channels is essential for understanding the molecular mechanism involved in neuronal ion channel regulation in normal and pathological conditions.