Phosphoinositide Signaling at the Synapse

兴奋性突触处的磷酸肌醇信号传导产生改变突触功能的Ca 2+信号，并传播到细胞核，在那里它们导致转录反应。Snyder/Worley项目将研究突触信号转导的三个关键阶段。第1组代谢型受体（mGluR）刺激磷脂酶C产生IP 3，这引起钙从细胞内池释放。最近的研究表明，mGluR 5对可卡因的行为反应至关重要。Worley实验室研究了mGluRs及其由即刻早期基因Homer进行的功能调节。在正在进行的研究中，他们发现Homer 2基因缺失的小鼠对可卡因的反应增强。这些观察结果集中注意力在药物成瘾模型中调节mGluR功能的荷马的作用。目的1将产生mGluR突变的小鼠遗传模型，破坏与Homer和Shank的特异性相互作用。目的2将研究一种新的mGluR信号/支架蛋白。一个家族的蛋白质，被称为霍皮，被确定的基础上，他们的耦合mGluR与荷马。初步研究表明，霍皮夫妇组1 mGluR激活p21激活激酶（Pak），也许CDK 5。研究将包括条件霍皮基因敲除小鼠的产生和分析，以及信号传导的分子研究。目标3将研究将IP 3受体靶向兴奋性突触的分子机制。Snyder实验室对三磷酸肌醇（IP 3R）的脑受体有着长期的兴趣，并定义了参与其信号转导的重要相互作用。这种方法利用了最近的一项观察，即Shank诱导了包括IP 3R在内的棘的形成。为了确定在棘中积累所必需的IP 3R区域，IP 3R缺失突变体将与Shank在神经元中共表达。将在切片培养中确认关键发现。平行的生物化学研究将确定与IP 3R结构域相互作用的蛋白质，IP 3R结构域在其脊柱定位和功能中至关重要。这些研究将为mGluR 5/IP 3R信号复合物如何在突触处组装以及扰动如何导致精神疾病提供重要的新见解。

Phosphoinositide signaling at the excitatory synapse generates Ca2+ signals that modify the function of the synapse, and propagate to the nucleus where they result in transcriptional responses. The Snyder/Worley project will examine three critical stages in signal transduction at the synapse. Group 1 metabotropic receptors (mGluR) stimulate phospholipase C to generate IP3, which evokes release of calcium from intracellular pools. Recent studies indicate that mGluR5 is essential for behavioral responses to cocaine. The Worley laboratory has studied mGluRs and their functional modulation by the immediate early gene Homer. In ongoing studies, they find that mice with a genetic deletion of Homer 2 exhibit enhanced responses to cocaine . These observations focus attention on the role of Homer in regulating mGluR function in models of drug addiction. Aim 1 will generate mouse genetic models with mutations of mGluR that disrupt specific interactions with Homer and Shank. Aim 2 will examine a novel signaling/scaffold protein for mGluR. A family of proteins, termed Hopi, was identified based on their coupling to mGluR by interacting with Homer. Preliminary studies indicate that Hopi couples group 1 mGluR to activation of p21-activated kinase (Pak) and perhaps CDK5. Studies will include generation and analysis of conditional Hopi knockout mice, and as well as molecular studies of signaling. Aim 3 will examine molecular mechanisms that target IP3 receptors to the excitatory synapse. The Snyder laboratory has a long-standing interest in the brain receptor for inositol trisphosphate (IP3R) and has defined important interactions involved in its signal transduction. The approach exploits a recent observation that Shank induces the formation of spines that include IP3R. In order to define regions of the IP3R that are essential for accumulation in spines, IP3R deletion mutants will be co-expressed with Shank in neurons. Critical finding will be confirmed in slice cultures. Parallel biochemical studies will identify proteins that interact with the domain of the IP3R that is essential in its spine localization and function. These studies will provide important new insights into how the mGluR5/IP3R signaling complex is assembled at the synapse, and how perturbations contribute to mental illness.