Sodium Leak Channels and Regulation by Neurotransmitters

描述(由申请人提供)：这项提案集中在钠渗漏通道(NALCN)及其神经系统中神经递质的调节。NALCN离子通道属于这个家族，它还包括十个电压门控钙通道和十个钠通道。然而，NALCN通道是非选择性的(对钠、钙和钾是可渗透的)，并且该通道的激活不依赖于电压。在通道基因缺陷的突变小鼠中，存在呼吸节律缺陷，突变动物无法存活超过出生24小时。因此，NALCN是为数不多的动物生存所必需的离子通道之一。突变的海马神经元缺乏铯和TTX不敏感的钠泄漏电流，并且神经元膜电位对细胞外钠浓度的变化不敏感。通过Northern印迹和原位杂交，Aim 1将定位该基因在动物体内的表达。目标2将确定NALCN独特的离子选择性背后的分子机制。目的利用膜片钳技术比较野生型和突变型神经元的兴奋性，确定NALCN通道对神经元兴奋性的贡献。Aim 4将研究神经递质如何调节NALCN通道。这些研究的结果将揭示这种重要基因的生理作用。它们还可能揭示该蛋白的功能如何在瘫痪、癫痫和癫痫等生理和病理生理条件下影响神经元的兴奋性。

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.