Epithelial sodium channel is regulated by SNAP-23/syntaxin 1A interplay.
Epithelial sodium channel is regulated by SNAP-23/syntaxin 1A interplay.
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上皮钠通道受 SNAP-23/突触蛋白 1A 相互作用的调节。
DOI：
10.1016/j.bbrc.2006.03.093
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
McConnell,Blake
中科院分区：
文献类型：
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作者：
Saxena,SunilK;George,ConstantineM;Pinskiy,Vadim;McConnell,Blake
钠选择性阿米洛利敏感上皮通道（ENaC）位于顶端膜参与钠在紧密上皮细胞的重吸收。可溶性N-乙基马来酰亚胺敏感性附着受体（SNARE）在多种细胞系统中介导囊泡运输。突触融合蛋白（一种t-陷阱）已被证明与包括ENaC在内的许多离子通道相互作用并在功能上调节这些离子通道。在这项研究中，我们研究了SNAP-23，另一个SNARE蛋白，在HT-29结肠上皮细胞系统和非洲爪蟾卵母细胞的ENaC活性的作用。记录阿米洛利敏感的电流在两个系统中表明，SNAP-23调节通道功能，虽然需要更高的浓度来抑制非洲爪蟾卵母细胞中的ENaC。引入肉毒杆菌毒素A（一种切割SNAP-23的神经毒素），而不是肉毒杆菌毒素B或热灭活的肉毒杆菌毒素A，逆转了SNAP-23对阿米洛利敏感电流的抑制作用。然而，syntaxin 1A和SNAP-23结合描绘了一个复杂的场景，表明该通道在四级复合物内相互作用。当与ENaC共表达时，Synaptotagmin表达既不与阿米洛利敏感电流相互作用，也不对阿米洛利敏感电流产生任何影响。下拉分析表明ENaC和SNAP-23之间存在轻微的相互作用，在突触融合蛋白1A的存在下，这种相互作用变得更强。数据进一步表明SNAP-23可能与N-末端αENaC相互作用。这些功能和生物化学方法提供了ENaC和胞吐机制之间复杂关系的证据。我们的数据表明，SNARE蛋白的相互作用定义了钠通道功能的精细调节。
Sodium-selective amiloride-sensitive epithelial channel (ENaC) located in the apical membrane is involved in the reabsorption of sodium in tight epithelia. The soluble N-ethylmaleimide-sensitive attachment receptors (SNAREs) mediate vesicle trafficking in a variety of cell systems. Syntaxin (a t-SNARE) has been shown to interact with and functionally regulate a number of ion channels including ENaC. In this study, we investigated the role of SNAP-23, another SNARE protein, on ENaC activity in the HT-29 colonic epithelial cell system and Xenopus oocytes. Recording of amiloride-sensitive currents in both systems suggest that SNAP-23 modulates channel function, though a much higher concentration is required to inhibit ENaC in Xenopus oocytes. The introduction of Botulinum toxin A (a neurotoxin which cleaves SNAP-23), but not Botulinum toxin B or heat-inactivated Botulinum toxin A, reversed the inhibitory effect of SNAP-23 on amiloride-sensitive currents. However, syntaxin 1A and SNAP-23 combined portray a complex scenario that suggests that this channel interacts within a quaternary complex. Synaptotagmin expression neither interacts with, nor showed any effect on amiloride-sensitive currents when co-expressed with ENaC. Pull down assays suggest mild interaction between ENaC and SNAP-23, which gets stronger in the presence of syntaxin 1A. Data further suggest that SNAP-23 possibly interacts with the N-terminal αENaC. These functional and biochemical approaches provide evidence for a complex relationship between ENaC and the exocytotic machinery. Our data suggest that SNARE protein interplay defines the fine regulation of sodium channel function.