Modulation of Olfactory Bulb Neuron Current Properties

描述(申请人提供)：离子通道是多蛋白支架的组成部分，由分子蛋白质-蛋白质相互作用调节，以控制神经元的电兴奋性，并为下游细胞信号机制提供适当的亚细胞邻接。这项工作将集中在电压门控离子通道(Kv1.3)的非传统作用，主要表达在嗅球的二尖瓣细胞神经元，以了解电压门控活动对嗅觉编码的贡献。最近发现的K通道的多种作用--包括能量稳态、轴突靶向和神经元细胞结构的发展--还知之甚少。利用转基因小鼠模型(气味受体标记小鼠、Kv1.3缺失小鼠、YFP二尖瓣细胞小鼠和MC4R缺失小鼠)研究Kv1.3活性的多学科方法被提出，该方法结合了嗅球电生理学、蛋白质生物化学、鼻内激素/药物输送、嗅觉识别(行为)、系统生理学和嗅路解剖分析的方法，作为确定神经调节嗅球电压门控活动的机制细节和整体生理效应的手段。这一建议的具体目的是基于三个假设：1.与胰岛素受体激酶/磷酸酶级联中的信号蛋白相互作用调节Kv1.3离子通道的活性。2.Kv1.3离子通道的电压门控活动调节嗅球二尖瓣细胞的活动和嗅觉。3.基因靶向的Kv1.3通道蛋白和黑素皮质素4受体的缺失将提供该钾通道如何调节能量稳态的机制细节，该稳态通过葡萄糖利用来调节嗅觉能力。这项研究的长期目标是阐明电压门控离子通道活动的神经调节如何在嗅觉系统中引起不同的功能，如突触效率的长期可塑性变化，与能量代谢的联系，或微调气味受体及其中心靶点的表达。了解离子通道如何由丰富在嗅觉系统中的明确分子调节并参与代谢紊乱(糖尿病)和神经退行性疾病(阿尔茨海默氏症)的一般原理，以及为什么Kv1.3基因靶向缺失增强嗅觉能力并诱导对体重增加的抵抗，作为增加气味辨别或减轻能量平衡失衡(肥胖)的目标具有很大的翻译前景。与公共健康相关：65%的美国人超重；不想要的体重增加会增加心脏和循环的工作量，增加胰岛素抵抗，并诱发II型糖尿病。这项建议旨在阐明嗅球离子通道如何参与体重和能量代谢的基本细胞机制；嗅觉能力和肥胖之间是否存在联系？

Description (provided by applicant): Ion channels are a component of multiprotein scaffolds regulated by molecular protein-protein interactions to control electrical excitability of neurons and provide proper subcellular adjacencies to downstream cell signaling machinery. The work in this proposal will focus upon non-traditional roles of a voltage-gated ion channel (Kv1.3) predominantly expressed in mitral cell neurons of the olfactory bulb to understand the contribution of voltage-gated activity to olfactory coding. The recently uncovered, multifarious role for K channels - including energy homeostasis, axon targeting, and development of neuronal cytoarchitecture - is poorly understood. A multidisciplinary approach using transgenic mouse models (odorant receptor-tagged mice, Kv1.3-null mice, YFP mitral cell mice, and MC4R-null mice) to study Kv1.3 activity is proposed incorporating the METHODS of olfactory bulb electrophysiology, protein biochemistry, intranasal hormone/drug delivery, olfactory discrimination (behavior), systems physiology, and anatomical analysis of olfactory circuitry as a means for determining the mechanistic details and global physiological effects of neuromodulation of voltage-gated activity in the olfactory bulb. The SPECIFIC AIMS of this proposal are based on three HYPOTHESES: 1. Interactions with signaling proteins in the insulin receptor kinase/phosphatase cascade regulate Kv1.3 ion channel activity. 2. Voltage-gated activity from Kv1.3 ion channels modulates olfactory bulb mitral cell activity and olfactory acuity. 3. Gene-targeted deletions of Kv1.3 channel protein and the melanocortin 4 receptor will provide mechanistic details of how this potassium channel regulates energy homeostasis that modulates olfactory sensory ability via glucose utilization. The broad, long-term OBJECTIVE of this research is to elucidate how neuromodulation of voltage-gated ion channel activity can give rise to diverse functions in the olfactory system such as long-term plastic changes in synaptic efficacy, links to energy metabolism, or to fine tune the expression of odorant receptors and their central targets. Understanding the general principles of how ion channels are regulated by well defined molecules enriched in the olfactory system and involved in metabolic disorders (diabetes) and neurodegenerative diseases (Alzheimer's) and why gene-targeted deletion of Kv1.3 increases olfactory ability and induces resistance to weight gain, holds great translational promise as a target for increasing odor discrimination or lessening imbalance in energy homeostasis (obesity). PUBLIC HEALTH RELEVANCE: Sixty-five percent of Americans are overweight; unwanted weight gain induces an increased workload on the heart and circulation, increases insulin resistance, and precipitates type II Diabetes. This proposal is designed to elucidate the basic cellular mechanisms of how ion channels expressed in the olfactory bulb are involved in body weight and energy metabolism; is there a link between olfactory ability and obesity?