Molecular Analysis of Drosophila GABA Transporters

γ-氨基丁酸（GABA）是脊椎动物和无脊椎动物神经系统中的主要抑制性神经递质。GABA转运蛋白主要通过选择性地从突触间隙重摄取GABA来介导GABA刺激的抑制反应的终止。在这种生理背景下，有效的GABA转运机制确保了神经传递的保真度。此外，哺乳动物GABA转运蛋白亚型的多样性被认为调节GABA能神经传递的不同方面;初步工作表明果蝇也是如此。我们从果蝇头部文库中克隆了几个部分GABA转运蛋白同源cDNA，这些cDNA与哺乳动物GABA转运蛋白具有广泛的序列同源性。果蝇中GABA转运蛋白（DGATs）的存在有助于从分子遗传学的角度更好地理解GABA对行为的神经化学作用。我们推测，GABA介导的神经传递通过DGAT功能的扰动的改变将导致异常的行为。我们还假设DGAT家族的不同成员调节GABA介导的行为的不同方面。为了验证这些假设，我们将解决三个具体的目标：1）我们将分析在成年果蝇中，由GABA转运蛋白功能和GABA介导的神经传递的扰动引起的GABA诱导的行为。2)我们将通过在昆虫细胞中表达来鉴定果蝇GABA转运蛋白家族（DGATs）的不同成员，并对这些蛋白进行功能表征。3)我们将分析具有异常GABA转运蛋白表达的果蝇突变株的行为表型。拟议的工作将扩大我们的知识的基本监管机制GABA介导的神经传递。

Gamma-aminobutryic acid (GABA) is the principal inhibitory neurotransmitter in both vertebrate and invertebrate nervous systems. GABA transporters largely mediate termination of GABA-stimulated inhibitory responses by the selective reuptake of GABA from the synaptic cleft. In this physiological context, efficient GABA transport mechanisms ensure the fidelity of neurotransmission. In addition, diversity in the mammalian GABA transporter isoforms is believed to regulate different aspects of GABAergic neurotransmission; preliminary work suggests the same is true for Drosophila. We cloned several partial GABA transporter-homologous cDNAs from a Drosophila head library that displayed extensive sequence homology with mammalian GABA transporters. The existence of experimentally accessible GABA transporters in Drosophila (DGATs) facilitates undertaking a molecular- genetic approach to better understand the neurochemical actions of GABA on behaviors. We hypothesize that alterations in GABA-mediated neurotransmission via perturbations in DGAT function will result in aberrant behaviors. We also hypothesize that different members of the DGAT family regulate different aspects of GABA-mediated behaviors. To verify these hypotheses, we will address three specific aims: 1) We will analyze pharmacologically induced behaviors In the adult fly that result from perturbations in GABA transporter function and GABA- mediated neurotransmission. 2) We will identify distinct members of the Drosophila GABA transporter family (DGATs) and functionally characterize the proteins by expressing them in Insect cells. 3) We will analyze the behavioral phenotypes of mutant strains of flies with abnormal GABA transporter expression. The proposed work will extend our knowledge of basic regulatory mechanisms governing GABA-mediated neurotransmission.