Alternative splicing modulates inactivation of type 1 voltage-gated sodium channels by toggling an amino acid in the first S3-S4 linker.
Alternative splicing modulates inactivation of type 1 voltage-gated sodium channels by toggling an amino acid in the first S3-S4 linker.
复制标题
替代剪接调节1型电压门控钠通道的失活，通过在第一个S3-S4接头中切换氨基酸。
DOI：
10.1074/jbc.m111.250225
复制
发表时间：
2011-10-21
期刊：
影响因子：
--
通讯作者：
Schorge S
中科院分区：
文献类型：
--
作者：
Fletcher EV;Kullmann DM;Schorge S
背景：电压门控钠通道行为的微小变化可破坏神经元活动并引起严重的神经系统疾病。结果：通过改变单个氨基酸，一个保守的选择性剪接事件改变了通道失活的稳定性。结论：剪接可调节钠离子通道失活。意义：许多常用药物以钠通道失活为靶点；因此，剪接可以影响几种神经系统疾病的治疗。电压门控钠通道是动作电位上升的基础，是神经元兴奋性的基础。这些通道行为的微小变化足以改变神经元放电并引发癫痫发作。这些通道受到高度保守的选择性剪接的影响，影响了第三跨膜段（S3）和第一域电压传感器（S4）之间的短连接。这种选择性剪接的生物物理后果尚不完全清楚。在这里，我们关注与人类癫痫有关的1型钠通道（Nav1.1）。我们表明，选择性剪接的功能后果对记录条件高度敏感，包括主要细胞内阴离子的身份和记录温度。特别是，含有交替外显子5N的通道的失活动力学比含有外显子5A的通道对细胞内氟离子和温度变化更敏感。此外，含有5N外显子的Nav1.1通道在生理温度下从失活中恢复得更快。外显子5A和5N之间有三个氨基酸不同。然而，失活的敏感性和稳定性的变化是由含有外显子5A的通道中从天冬氨酸到天冬酰胺的单一保守变化再现的，这足以使它们的行为与含有完整外显子5N序列的通道相似。这些数据表明，该位点的剪接可以改变钠通道的失活，并揭示了剪接与稳定钠通道失活的抗癫痫药物之间可能存在相互作用。
Background: Small changes in voltage-gated sodium channel behavior can disrupt neuronal activity and cause severe neurological disorders. Results: By changing a single amino acid, a conserved alternative splicing event modifies the stability of channel inactivation. Conclusion: Splicing can regulate inactivation of sodium channels. Significance: Many commonly used drugs target sodium channel inactivation; consequently, splicing could affect treatment of several neurological disorders. Voltage-gated sodium channels underlie the upstroke of action potentials and are fundamental to neuronal excitability. Small changes in the behavior of these channels are sufficient to change neuronal firing and trigger seizures. These channels are subject to highly conserved alternative splicing, affecting the short linker between the third transmembrane segment (S3) and the voltage sensor (S4) in their first domain. The biophysical consequences of this alternative splicing are incompletely understood. Here we focus on type 1 sodium channels (Nav1.1) that are implicated in human epilepsy. We show that the functional consequences of alternative splicing are highly sensitive to recording conditions, including the identity of the major intracellular anion and the recording temperature. In particular, the inactivation kinetics of channels containing the alternate exon 5N are more sensitive to intracellular fluoride ions and to changing temperature than channels containing exon 5A. Moreover, Nav1.1 channels containing exon 5N recover from inactivation more rapidly at physiological temperatures. Three amino acids differ between exons 5A and 5N. However, the changes in sensitivity and stability of inactivation were reproduced by a single conserved change from aspartate to asparagine in channels containing exon 5A, which was sufficient to make them behave like channels containing the complete exon 5N sequence. These data suggest that splicing at this site can modify the inactivation of sodium channels and reveal a possible interaction between splicing and anti-epileptic drugs that stabilize sodium channel inactivation.