Synapse Remodeling and Neuronal MHC Class I

描述(申请人提供)：这项研究的长期目标是了解大脑发育过程中的经验如何通过神经回路的活动驱动功能转化为突触连接的持久结构变化。这项研究计划的具体目标是检验这一假说，即发育过程中的活性依赖性突触重构和成人突触可塑性涉及一个在免疫系统中具有众所周知功能的大基因家族：MHC I类基因(人类的HLA基因)。神经元MHC I类mRNA的表达在基于无偏向PCR的差异筛选中被意外发现，以寻找受神经活动调控的基因；缺乏MHC I功能的小鼠的初步遗传学研究随后揭示了视觉系统发育和海马区可塑性对I类MHC的需求(Huh等人，2000)。这里提出的研究目标是更多地了解I类MHC如何在正常、未受损伤的中枢神经系统中发挥作用。提出了三个具体目标。1)通过免疫组织化学、特定脑区RT-PCR和原位杂交检测中枢神经系统的表达，确定神经元中MHC-I类蛋白是否位于突触，以及MHCI家族成员的表达模式是否存在分子逻辑。2)通过标准微电极记录和对野生型、功能缺失(B2M/TAP1)和功能获得(NSE-DB)突变小鼠的海马片谷氨酸受体转运的生化评估，确定MHC I类在海马区双向突触可塑性中的作用。3)通过对体外培养的野生型和突变型海马神经元的突触结构和生理学的研究，确定I类MHC是否是将神经活动转化为突触持久的解剖学变化所必需的。这些实验的结果应该会扩大我们对依赖使用的变化的理解，无论是在发育中还是在成人中，神经回路的结构都是如何编码的。突触和回路的变化发生在童年学习的关键时期，以及一生中记忆的形成。了解相关的分子和机制对于解决并最终治愈学习和记忆障碍也是至关重要的，从阅读障碍、自闭症和其他学习障碍，到阿尔茨海默氏症和其他老化大脑的记忆障碍。

DESCRIPTION (provided by applicant): The long term goal of this research is to learn how experience during brain development, mediated by the activity-driven functioning of neural circuits, is translated into lasting structural change in synaptic connectivity. The specific goal of this research proposal is to examine the hypothesis that activity-dependent synaptic remodeling in development, and adult synaptic plasticity, involve a large gene family with well-known function in the immune system: MHC Class I genes (HLA genes in humans). Neuronal MHC Class I mRNA expression was discovered unexpectedly in an unbiased PCR-based differential screen for genes regulated by neural activity; initial genetic studies in mice lacking MHC I function then revealed a requirement for Class I MHC in visual system development and hippocampal plasticity (Huh et al, 2000). The goal of research proposed here is to learn more about how Class I MHC functions in the normal, uninjured CNS. Three specific aims are proposed. 1) Determine whether MHC Class I protein in neurons is located at synapses and whether there is a molecular logic to expression patterns of MHCI family members by means of immunohistochemistry, RT-PCR of specific brain regions, and in situ hybridization to examine CNS expression. 2) Determine how MHC Class I functions in bidirectional synaptic plasticity in the hippocampus by standard microelectrode recordings and biochemical assessment of glutamate receptor trafficking in hippocampal slices from wildtype, loss (B2m/TAP1) and gain of function (NSE-Db) mutant mice. 3) Determine if Class I MHC is necessary for the translation of neural activity into lasting anatomical change at synapses by examining structure and physiology of synapses in wild type and mutant hippocampal neurons in vitro following pharmacological manipulations that alter neural activity. The results of these experiments should broaden our understanding of how use-dependent changes, both in development and in adult, are encoded in the structure of neural circuits. Changes in synapses and circuits occur during critical periods of learning in childhood, as well as in memory formation throughout life. Understanding the molecules and mechanisms involved is also crucial for addressing and ultimately curing disorders of learning and memory, from Dyslexia, Autism and other learning disorders, to Alzheimer's and other memory disorders of the aging brain.