MECHANISMS OF LONG TERM SYNAPTIC PLASTICITY

在分析记忆的细胞基础的一个基本问题是在短期和长期记忆之间的过渡中，调节细胞机制的不同作用的重要性。短期和长期突触可塑性之间的主要区别之一是对蛋白质合成的需求。本研究的目的是研究与长期突触可塑性相关的细胞变化有关的特定蛋白质的参与。许多蛋白质已经被确定，其水平被改变作为长期敏感的防御退缩反射的结果，这是一个长期记忆形成的充分研究模型。其中一种蛋白最近被鉴定为apTBL-1 （apTBL-1）。在其他系统中，apTBL-1的同源物作为生长因子TGFbeta超家族的激活剂。先前的一项研究表明，TGFbeta的应用诱导了孤立神经节中apusisia感觉-运动连接的长期促进。在Specific Aim 1中，我们将测试apTBL-1诱导培养神经元的长期突触促进（部分介导长期致敏）的能力。此外，针对apTBL-1的特异性抗体的能力将被测试其阻断5-HT（一种已知的神经调节剂）诱导的长期促进的能力。在Specific Aim 2中，TGFbeta对培养的感觉-运动连接产生长期促进的能力将被测试。这项研究将tgfβ的作用定位于感觉或运动神经元。tgf受体的分布也将使用免疫组织化学技术来确定。将进行Western blots以确认用于染色的抗体的特异性。在Specific Aim 3中，将研究将tgf - β信号转导到细胞核的信号机制。具体来说，我们将分析MAPK和SMAD家族转录因子在tgf - β信号传导中的作用。这个项目将提供对简单学习形式的分子机制的见解。

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.