Regulating Serotonin Transporter Conducting States

描述（由申请人提供）：血清素（5HT）在攻击性、认知、饮食、情绪、运动活动、疼痛和睡眠中起着至关重要的作用。5HT转运蛋白（SERTs）是神经元膜蛋白，通过摄取调节细胞外5HT浓度。sert之所以引起人们的兴趣，还因为它们是治疗药物（如抗抑郁药）和滥用药物（如可卡因、安非他明）的靶点。有趣的是，sert具有多种导电状态，有时作为离子通道，而其他时候更多地作为5HT的传统转运体。然而，决定SERT占据哪个状态的调节因子，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。

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.