Molecular Properties of Synapses in the Visual Cortex

描述(申请人提供)：我的实验室的一个长期目标是了解大脑中潜在的信号传递的分子机制，特别是当它与更高的大脑功能和疾病状态有关时。在脊椎动物中，视觉信息的处理--细节如何被提取和重组以形成我们的感知--关键取决于视觉皮质第2/3层的局部回路。虽然需要许多细节来定义这一电路，但我们的工作集中在调节兴奋性(谷氨酸能)锥体输入到抑制性中间神经元的动态因素上，主要集中在突触后机制上。特别是，我们感兴趣的是蛋白质之间的相互作用如何影响谷氨酸受体的门控特性。为此，我们将利用异源表达系统来研究谷氨酸受体和细胞内蛋白之间的相互作用机制，以及这些相互作用如何影响通道功能，并使用第2/3层突触连接(锥体到中间神经元)细胞的配对记录来研究这些蛋白质-蛋白质相互作用如何直接影响突触幅度及其频率依赖性。具体地说，我们将研究(1)突触相关蛋白97(SAP97)与AMPAR Glur-A通道相互作用的机制，特别是当它与改变它们的生物物理性质有关时。初步数据表明，SAP97改变了GluR-A AMPAR的门控属性，这里提出的实验将定义这些新作用的分子基础，提供对蛋白质-蛋白质相互作用的基本见解，以及这些相互作用如何影响关键配体门控离子通道的动态功能。(2)SAP97与GluR-A在第2/3层相互作用的功能意义。SAP97在多极中间神经元中表达，我们的实验将专门探讨Glur-A/SAP97相互作用对突触功能动力学的功能意义。这项工作是对大脑中信号分子基础的基础研究。定义信号传递的基本原则为理解疾病状态下可能发生的干扰奠定了基础。

DESCRIPTION (provided by applicant): A long-term objective of my laboratory is to understand the molecular mechanisms underlying signaling in the brain, especially as it relates to higher brain functions and disease states. In vertebrates, processing of visual information-how details are extracted and recombined to form our perceptions-depends critically on the local circuitry in layers 2/3 of the visual cortex. Although a variety of details are required to define this circuitry, our work focuses on the dynamic factors regulating the excitatory (glutamatergic) pyramidal inputs to inhibitory interneurons, focusing primarily on postsynaptic mechanisms. In particular, we are interested in how protein-protein interactions can affect the gating properties of glutamate receptors. To do so, we will take advantage of heterologous expression systems to study mechanisms of interaction between glutamate receptors and intracellular proteins and how these interactions affect channel function and use paired recordings from synaptically connected (pyramidal-to-interneuron) cells in layers 2/3 to study how these protein-protein interactions directly affect synaptic amplitudes and their frequency dependence. Specifically, we will address (1) The mechanism of synapse-associated protein 97 (SAP97) interaction with AMPAR GluR-A channels, specifically as it relates to changing their biophysical properties. Preliminary data indicate that SAP97 alters the gating properties of GluR-A AMPARs, and experiments proposed here will define the molecular basis for these novel actions providing fundamental insights into protein-protein interactions and how these interactions affect the dynamic function of a key ligand-gated ion channel. (2) The functional significance of SAP97 interaction with GluR-A in layers 2/3. SAP97 is expressed in multipolar interneurons and our proposed experiments will specifically address the functional significance of GluR-A/SAP97 interaction to the dynamics of synaptic function. This work is basic research in the molecular basis of signaling in the brain. Defining basic principles of signaling provides a foundation for understanding the disruptions that can occur in disease states.