Sodium Leak Channels and Regulation by Neurotransmitters

描述（由申请人提供）：该提案重点关注钠泄漏通道（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（钠、钙和钾可渗透），并且通道的激活与电压无关。在通道基因缺陷的突变小鼠中，呼吸节律存在缺陷，并且突变动物无法存活超过出生24小时。因此，NALCN是动物生存不可缺少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，并且神经元的膜电位对细胞外钠浓度的变化不敏感。使用 Northern 印迹和原位杂交，目标 1 将定位动物中的基因表达。目标 2 将确定 NALCN 独特离子选择性的分子机制。目标 3 将使用膜片钳比较野生型和突变型神经元的兴奋性，并确定 NALCN 通道对神经元兴奋性的贡献。目标 4 将检查 NALCN 通道如何受神经递质调节。这些研究的结果将揭示这一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（如瘫痪、癫痫发作和癫痫）中的神经元兴奋性。

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.