Neurotrophin-dependent regulation of voltage-gated sodium channels

摘要 神经精神障碍被认为是由大脑可塑性的复杂变化引起的。最近的证据 指出离子通道复合物是细胞可塑性的中心，赋予疾病脆弱性或保护作用。 这取决于信道管理状态。在延髓核（NAc）中的中型棘神经元（MSN）中， 作为高度脆弱细胞的一种亚型，内在放电的神经适应性变化由神经营养因子介导 脑源性神经营养因子（BDNF）/原肌球蛋白受体激酶B（Trk B）信号传导。 然而， 这些变化发生的机制仍然知之甚少。 MSN的内在放电依赖于电压门控Na+（Nav）大分子复合物的完整性。 通道Nav1.6及其辅助调节成纤维细胞生长因子14（FGF 14），并受 糖原合成酶激酶3（GSK 3）β，BDNF/TrkB信号传导的下游效应子。在这里，我们提供 Nav1.6、FGF 14和GSK 3 β作为下游大分子信号传导复合物的令人兴奋的新证据 BDNF/TrkB对MSNs神经元可塑性至关重要。使用一系列体外和细胞测定，细胞成像， 和电生理学，我们表明Nav1.6通道的稳定性，磷酸化和功能活性是 与BDNF水平和激酶活性成比例，由此低水平的 BDNF预测恢复力， 高水平介导由神经元放电变化所赋予的易感表型。我们将进行全面的 一系列生物物理学、生物化学和电生理学研究，结合药理学和病毒学 基于载体的体内基因转移方法，以评估BDNF/TrkB信号转导对大分子 在本发明的一个实施方案中，本发明的目的是描述在细胞内Nav1.6通道的组成（Aim 1）、亚细胞靶向（Aim 2）和功能特性（Aim 3）。 MSN的神经适应性可塑性的背景。这些研究的结果可能会导致 通过研究分子通路开发神经精神疾病易感性的生物标志物 在相关的实验模型中，这是生物精神病学非常感兴趣的一个领域。

ABSTRACT Neuropsychiatric disorders are thought to arise from complex changes of brain plasticity. Recent evidence points toward ion channel complexes as cellular hubs of plasticity that confer disease vulnerability or protection depending on the channel regulatory state. In medium spiny neurons (MSNs) in the nucleus accumbens (NAc), a subtype of highly vulnerable cells, neuroadaptive changes in intrinsic firing are mediated by neurotrophin brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) signaling. Yet, the molecular mechanisms by which these changes occur are still poorly understood. Intrinsic firing in MSN relies on the integrity of the macromolecular complex of the voltage-gated Na+ (Nav) channel Nav1.6 and its accessory regulatory fibroblast growth factor 14 (FGF14) and is subject to regulation by glycogen synthase kinase 3 (GSK3) β, a downstream effector of BDNF/TrkB signaling. Here, we provide exciting new evidence for the Nav1.6, FGF14 and GSK3β as a macromolecular signaling complex downstream of BDNF/TrkB critical for MSNs neuronal plasticity. Using an array of in vitro and in cell assays, cell imaging, and electrophysiology, we show that stability, phosphorylation and functional activity of the Nav1.6 channel are proportional to the level of BDNF and the kinase activity, whereby low level of BDNF predicts resilience and high level mediates a susceptible phenotype conferred by changes in neuron firing. We will conduct a full range of biophysical, biochemical and electrophysiological studies combined with pharmacological and viral vector-based in vivo gene transfer methods to evaluate the impact of BDNF/TrkB signaling on macromolecular composition (Aim 1), subcellular targeting (Aim 2) and functional properties (Aim 3) of the Nav1.6 channel in the context of neuroadaptive plasticity of MSNs. Outcomes of these studies could potentially lead to the development of biomarkers of susceptibility to neuropsychiatric disorders by investigating molecular pathways in relevant experimental models, an area of great interest for biological psychiatry.