Neurotransmitter Transport

描述（由申请人提供）：5-羟色胺转运蛋白（SERT）负责降低释放这种神经递质的突触附近的5-羟色胺（5-HT）水平。在这个过程中，5-HT被转运到释放它的细胞中，在那里它可以重新包装成突触囊泡。抑制SERT的药物增加突触5-HT的水平并延长其作用的持续时间。这些药物包括滥用的物质，如可卡因，和治疗药物，如抗抑郁药。一些药物是SERT的底物，如3，4-亚甲二氧基甲基苯丙胺（a.k.a.“摇头丸”）通过SERT从神经元释放5-HT起作用。从这些药物的深刻行为后果来看，很明显，SERT活性的调节可能是正常大脑生理学中的关键事件。五年前，我们在强迫症患者身上发现了一种变异的转运蛋白。这种突变体显然是激活的组成方式通常涉及环GMP（cGMP）的途径。此后，我们发现该缺陷代表去除SERT分子中276位磷酸基团的能力的缺陷。该位置被cGMP依赖性酶PKG磷酸化。作为了解神经递质转运蛋白的结构和功能的长期目标的一部分，该提案概述了研究磷酸化和去磷酸化SERT的酶与cGMP信号通路的其他组分沿着的关联的计划。SERT构象受磷酸化影响的机制也将被研究。所有这些研究都是为了验证cGMP的产生激活信号通路的假设，该信号通路使SERT磷酸化和去磷酸化，从而增加和减少周转率。我们还将测试预测，构象变化的基础上的影响，5-HT运输SERT与调节蛋白的相互作用。 公共卫生相关性：该提案涉及5-羟色胺转运体的调节机制，5-羟色胺转运体是滥用药物和抗抑郁药的靶点。在与精神疾病相关的这种转运蛋白的突变形式中发现了调节缺陷。我们的目标是了解在分子水平上负责这种调节的结构和机制事件。

DESCRIPTION (provided by applicant): Serotonin transporter (SERT) is responsible for lowering serotonin (5-HT) levels in the vicinity of synapses that release this neurotransmitter. In this process, 5-HT is transported into the cell from which it was released, where it is available for repackaging into synaptic vesicles. Drugs that inhibit SERT increase the level of synaptic 5-HT and lengthen the duration of its action. These drugs include abused substances such as cocaine, and therapeutic drugs such as antidepressants. Some drugs that are substrates for SERT, such as 3,4-methylenedioxymethamphetamine (a.k.a. "ecstasy") act through SERT to release 5-HT from neurons. From the profound behavioral consequences of these drugs, it is clear that regulation of SERT activity is likely to be a key event in normal brain physiology. Five years ago we found a mutant form of the transporter in patients with obsessive compulsive disorder. This mutant is apparently activated in a constitutive fashion by a pathway normally involving cyclic GMP (cGMP). We have since discovered that the defect represents a defect in the ability to remove a phosphate group at position 276 in the SERT molecule. This position is phosphorylated by a cGMP-dependent enzyme, PKG. As part of the long term goal to understand the structure and function of neurotransmitter transporters, this proposal outlines plans to investigate the association of enzymes that phosphorylate and dephosphorylate SERT, along with other components of the cGMP signaling pathway. The mechanism by which SERT conformation is affected by phosphorylation will also be investigated. All of these studies are directed to testing the hypothesis that production of cGMP activates a signaling pathway that phosphorylates and dephosphorylates SERT with the consequent increase and decrease in turnover rate. We will also test the prediction that conformational changes underlie the effects that 5-HT transport has on SERT interaction with regulatory proteins. PUBLIC HEALTH RELEVANCE: This proposal concerns a mechanism for regulation of serotonin transporter, a target for drugs of abuse and antidepressants. Defects in regulation were found in a mutant form of this transporter associated with psychiatric disorders. We aim to understand the structural and mechanistic events that are responsible for this regulation at a molecular level.