Sodium Leak Channels and Regulation by Neurotransmitters

描述（由申请人提供）：该提案侧重于钠泄漏通道（NALCN）及其通过神经系统中的神经递质进行的调节。NALCN离子通道属于还包括十个电压门控钙通道和十个钠通道的家族。然而，NALCN通道是非选择性的（可渗透钠、钙和钾），并且通道的激活是电压非依赖性的。在通道基因缺陷的突变小鼠中，呼吸节律存在缺陷，并且突变动物不能存活超过出生后24小时。因此，NALCN是动物生存所必需的少数离子通道之一。突变的海马神经元缺乏铯和TTX不敏感的钠漏电流，神经元的膜电位对细胞外钠浓度的变化不敏感。利用北方印迹和原位杂交，aim 1将在动物中定位基因表达。目的2将确定NALCN独特的离子选择性的分子机制。目的3采用膜片钳技术比较野生型和突变型神经元的兴奋性，并探讨NALCN通道对神经元兴奋性的贡献。目的4将研究NALCN通道如何受神经递质调节。这些研究的结果将揭示这个重要基因的生理作用。它们还可能揭示蛋白质的功能如何影响生理和病理生理条件下的神经元兴奋性，如瘫痪，癫痫发作和癫痫。

DESCRIPTION (provided by applicant): This proposal focuses on a sodium leak channel (NALCN) and its regulation by neurotransmitters in the nervous systems. NALCN ion channel belongs to the family that also includes the ten voltage-gated calcium channels and ten sodium channels. However, the NALCN channel is non-selective (permeable to sodium, calcium and potassium), and the channel's activation is voltage-independent. In the mutant mice deficient in the channel gene, there is defect in breathing rhythm and the mutant animals do not survive beyond 24 hours of birth. Thus, NALCN is one of the few ion channels indispensable for animal's survival. The mutant hippocampal neurons lack the cesium and TTX-insensitive sodium leak current and the neurons' membrane potential is little sensitive to changes in extracellular sodium concentrations. Using Northern blot and in situ hybridization, aim 1 will localize the gene expression in the animal. Aim 2 will determine the molecular mechanisms underlying NALCN's unique ion selectivity. Aim 3 will use patch clamp to compare the excitabilities of the wild-type and the mutant neurons and determine the contribution of NALCN channel to neuronal excitability. Aim 4 will examine how the NALCN channel is regulated by neurotransmitters. Results from these studies will reveal the physiological roles of this vital gene. They may also reveal how the function of the protein can influence neuronal excitabilities in physiological and pathophysiological conditions such as paralysis, seizure and epilepsy.