MECHANISMS OF LONG TERM SYNAPTIC PLASTICITY

在分析记忆的细胞基础的一个基本问题是调节细胞机制的差异作用的重要性，在短期和长期记忆之间的过渡。 短期和长期突触可塑性之间的主要区别之一是蛋白质合成的要求。 这项研究的目的是研究与长期突触可塑性相关的细胞变化中涉及的特定蛋白质。 许多蛋白质已被确定，其水平的改变是由于长期敏感的防御性退缩反射的记忆丧失，长期记忆形成的一个良好的研究模型。 这些蛋白质之一最近已被鉴定为阿托洛/骨形态发生蛋白样-1（apTBL-1）。 在其他系统中，apTBL-1的同源物作为TGF β超家族生长因子的激活剂。 先前的研究表明，TGF β的应用诱导孤立神经节中的感觉-运动连接的长期促进。 在特定目标1中，将测试apTBL-1诱导培养的神经元的长期突触易化的能力，其部分介导长期致敏。 此外，将测试针对apTBL-1的特异性抗体阻断5-HT（一种已知的神经调节剂）诱导长期易化的能力。 在具体目标2中，将测试TGF β对培养的感觉-运动连接产生长期促进的能力。 这项研究将定位TGF β的作用，感觉或运动神经元。 还将使用免疫组织化学技术测定TGF β受体的分布。 将进行蛋白质印迹，以确认用于染色的抗体的特异性。 在具体目标3中，将研究将TGF β信号传导至细胞核的信号传导机制。 具体而言，将分析MAPK和SMAD家族转录因子的活性在TGF β信号传导中的作用。 该项目将提供对简单学习形式下的分子机制的见解。

A fundamental issue in the analysis of the cellular basis of memory is the importance of the differential roles of regulatory cellular mechanisms in the transition between short- and long-term memory. One of the main differences between short- and long-term synaptic plasticity is the requirement for protein synthesis. The objective of the proposed research is to investigate the involvement of specific proteins that have been implicated in the cellular changes associated with long-term synaptic plasticity. Many proteins have been identified whose levels are altered as a result of long-term sensitization of defensive withdrawal reflexes of Aplysia, a well-studied model for long-term memory formation. One of these proteins has recently been identified as Aplysia tolloid/bone morphogenetic protein like-1 (apTBL-1). In other systems, homologues of apTBL-1 act as activators of the TGFbeta superfamily of growth factors. A previous study has shown that application of TGFbeta induces long-term facilitation of Aplysia sensory-motor connections in isolated ganglia. In Specific Aim 1, the ability of apTBL-1 to induce long-term synaptic facilitation, which partly mediates long-term sensitization, of cultured neurons will be tested. Further, the ability of a specific antibody against apTBL-1 will be tested for its ability to block the induction of long-term facilitation by 5-HT, a known neuromodulator. In Specific Aim 2, the ability of TGFbeta to produce long-term facilitation of cultured sensory-motor connections will be tested. This study will localize TGFbeta's action to either or both the sensory or motor neuron. The distribution of TGFbeta receptors will also be determined using immunohistochemical techniques. Western blots will be performed to confirm the specificity of the antibodies used for the staining. In Specific Aim 3, the signaling mechanisms which transduce TGFbeta signals to the nucleus will be investigated. Specifically, the activities of MAPK and the SMAD family of transcription factors will be analyzed for their roles in TGFbeta signaling. This project will provide insights into the molecular mechanisms underlying simple forms of learning.