Protein Trafficking Regulating the Formation of GABAergic Synapses

项目摘要 -氨基丁酸(GABA)的神经抑制对正常的大脑功能至关重要，这从以下几个方面可见一斑 与多种破坏性神经和精神疾病相关的GABA能传递缺陷 精神障碍包括癫痫、焦虑、情绪障碍、精神发育迟滞和许多其他疾病。中国的赤字 GABA能传递通常与表达、细胞分布或功能缺陷有关 GABA-A受体的特性。在这里，我们将重点放在棕榈酰化这一极其重要的机制上 控制GABA-A受体和突触细胞黏附分子神经连接素的运输，这两种受体都是 对GABA能抑制性突触传递至关重要。我们的初步实验表明， 在体外，GABA-A受体的Gamma2亚单位和神经连接素2(NL2)被选择性地棕榈酰化 结构上相关的棕榈酰基转移酶，GoDZ和SERZ-β(也称为zDHHC3和7)。棕榈酰化 通过突触后神经元中的这些酶有助于GABA-A受体的正常运输 GABA能神经支配与GABA能突触的正常功能此外，NL2的积累在 突触需要包含GABA-A受体的突触后Gamma2亚单位。加在一起，这些 初步发现导致我们提出了中心假设，即GodZ/SERZ-？介导 NL2和GABA-A受体之间的棕榈酰化和功能协同作用在 GABA能抑制性突触的形成和突触后分化。为了进一步测试这一点 假设我们将I)测试GOD/SERZ-1在棕榈酰化和GABA-A转运中的作用 受体，II)检测GOD/SERZ-1在棕榈酰化和NL2转运中的功能，III)分析 β2亚基GABA-A受体与NL2在GABA能神经元形成中的协同作用 突触。这些实验将一起提供对一种机制的透彻理解， 通过GABA能终末对GABA受体的忠实定位，从而有助于 GABA能抑制性突触的组装和分化。

Project Summary Neural inhibition by ?-aminobutyric acid (GABA) is vitally important for normal brain function as is evident from deficits in GABAergic transmission associated with a wide range of devastating neurological and psychiatric disorders including epilepsy, anxiety, mood disorders, mental retardation, and many others. Deficits in GABAergic transmission are commonly associated with deficits in expression, cellular distribution, or functional properties of GABA-A receptors. Here we focus on palmitoylation as a critically important mechanism that controls the trafficking of GABA-A receptors and the synaptic cell adhesion molecule neuroligin, which both are critically important for GABAergic inhibitory synaptic transmission. Our preliminary experiments show that the gamma2 subunit of GABA-A receptors and neuroligin 2 (NL2) are in vitro palmitoylated selectively by the same struturally related palmitoyltransferases, GODZ and SERZ-beta (also known as zDHHC3 and 7). Palmitoylation by these enzymes in postsynaptic neurons contributes to normal trafficking of GABA-A receptors, normal GABAergic innervation and normal function of GABAergic synapses. Moreover, accumulation of NL2 at synapses requires postsynaptic gamma2 subunit containing GABA-A receptors. Together, these preliminary findings lead us to propose the central hypothesis that GODZ/SERZ-¿-mediated palmitoylation and functional cooperativity between NL2 and GABA-A receptors play important roles in formation and postsynaptic differentiation of GABAergic inhibitory synapses. To further test this hypothesis we will i) test the function of GODD/SERZ-¿ in palmitoylation and trafficking of GABA-A receptors, ii) test the function of GODD/SERZ-¿ in palmitoylation and trafficking of NL2, and iii) analyze cooperativity between ?2 subunit-containing GABA-A receptors and NL2 in the formation of GABAergic synapses. Together these experiments will provide a thorough understanding of a mechanism that contributes to faithful apposition of GABAA receptors across form GABAergic terminals and thereby contributes to assembly and differentiation of GABAergic inhibitory synapses.