Regulating Serotonin Transporter Conducting States

描述(申请人提供)：5-羟色胺(5-羟色胺)在攻击性、认知、饮食、情绪、运动活动、疼痛和睡眠中起着关键作用。5-羟色胺转运体(5-羟色胺转运体)是神经细胞膜蛋白，通过摄取调节细胞外5-羟色胺浓度。SERTS也令人感兴趣，因为它们是治疗药物(例如抗抑郁药)和滥用药物(例如可卡因、安非他明)的目标。有趣的是，SERTS有多种传导状态，有时作为离子通道，有时更像传统的5-羟色胺转运体。然而，决定SERT处于哪种状态的调节因素，以及这些传导状态在内源性表达SERT的神经元中的功能作用尚不清楚。 初步数据表明，SERT所处的传导状态取决于SERT与其他蛋白质的相互作用。目的1验证钙通过影响SERT相互作用使SERT在不同状态间转换的假说，从而为调节SERT功能提供一种生理机制。目的2研究钙离子影响SERT状态的信号转导途径。目的3研究5-羟色胺摄取的状态依赖性差异。目的4验证苯丙胺失调钙介导的SERT电导状态转变的假说，并研究这种作用的机制。目的5通过检测在SERT底物存在下的状态依赖性细胞兴奋性，研究这些状态在内源性表达SERT的丘脑皮质神经元中所起的作用。 这些实验将在细胞表达系统和内源性表达SERT的神经元中使用生化、药理学和电生理学方法进行。这些实验将增加我们对正常SERT功能的理解，以及针对SERT的滥用药物如何调节其影响。了解调节SERT的因素对于设计治疗5-羟色胺转运体介导的疾病的策略也可能很重要。

DESCRIPTION (provided by applicant): Serotonin (5HT) plays a crucial role in aggression, cognition, eating, mood, motor activity, pain, and sleep. 5HT transporters (SERTs) are neuronal membrane proteins that regulate, via uptake, extracellular 5HT concentrations. SERTs are also of interest because they are targets of therapeutics (e.g., antidepressants) and drugs of abuse (e.g., cocaine, amphetamine). Interestingly, SERTs have multiple conducting states, sometimes functioning as ion channels, and other times functioning more as traditional transporters of 5HT. However, the regulatory factors that determine which state SERT occupies, and the functional roles of these conducting states in neurons that endogenously express SERT are unknown. Preliminary data show that the conducting state that SERT occupies depends on SERT's interaction with other proteins. Aim 1 tests the hypothesis that calcium shifts SERT between its states by influencing this interaction, thus providing a physiological mechanism for regulating SERT function. Aim 2 examines the signal transduction pathways by which calcium influences which state SERT occupies. Aim 3 examines state-dependent differences in 5HT uptake. Aim 4 tests the hypothesis that amphetamine dysregulates the calcium-mediated shift in SERT conductance states, and examines the mechanisms underlying this effect. Aim 5 examines the role that these states play in thalamocortical neurons that endogenously express SERT by examining state-dependent cell excitability in the presence of SERT substrates. The experiments will be performed using biochemical, pharmacological, and electrophysiological approaches in cell expression systems and in neurons that endogenously express SERT. These experiments will add to our understanding of normal SERT function and how drugs of abuse that target SERT may mediate their effects. Understanding the factors that regulate SERT may also be important for the design of strategies useful in the treatment of serotonin transporter-mediated disorders.