AGRIN GENE EXPRESSION

AGRIN 基因表达

• 批准号: 6045726
• 负责人: MARTIN A SMITH
• 金额: $ 30.53万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-01 至 2003-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6045726
• 关键词: RNA splicing; agrin; developmental neurobiology; electron microscopy; gene expression; gene mutation; glutamate receptor; hippocampus; immunocytochemistry; in situ hybridization; neuromuscular junction; neurotransmitter receptor; polymerase chain reaction; protein binding; protein biosynthesis; protein structure function; protooncogene; receptor expression; synapses; synaptogenesis; tissue /cell culture

DESCRIPTION (Verbatim from Applicant's Abstract): Normal brain function depends on the rapid transfer of information between neurons at highly specialized structures known as synapses. Understanding the mechanisms that direct the formation of synapses during development and their maintenance in the adult are, therefore, fundamental problems in neurobiology. Most of what we know about the development of chemical synapses comes from studies of the neuromuscular junction, where signals exchanged between motor neurons and the skeletal muscle fibers they innervate coordinate differentiation of the motor nerve terminal and postsynaptic apparatus in the muscle fiber. Compelling evidence now exists to show that one such signal is an extracellular matrix molecule called agrin, which plays a key role in the motor neuron induced organization of synaptic components in the muscle fiber. In contrast to the neuromuscular junction, relatively little is known about the mechanisms that direct neuron-neuron synapse formation in the central nervous system. We have shown that agrin is expressed in mammalian brain, consistent with a role for agrin in neuron-neuron synapse formation. Surprisingly, early stages of synaptogenesis between cortical neurons cultured from agrin knock-out mice appear normal, raising the question of what, if any, function agrin serves in brain. We have addressed this issue using expression of the immediate early gene c-fos and neural injury to monitor neuronal activity and show that agrin-deficient cultured cortical neurons exhibit reduced sensitivity to excitatory amino acids. These studies are the first to establish a CNS neuronal phenotype for a mutation in the agrin gene and suggest an important role for agrin in regulating glutamate receptor expression or function. Experiments are proposed that seek to test this hypothesis and identify the cellular defect caused by the mutation. Evidence that agrin is required for normal development of cortical neurons predicts the existence of a neuronal signal transduction pathway for agrin. Preliminary data confirm this hypothesis showing that agrin induces a dose-dependent saturable increase in Fos levels in cultured cortical neurons. Biochemical studies indicate that agrin induction of c-fos is similar to but distinct from signals mediating agrin-induced clustering of acetylcholine receptors in muscle. Additional experiments are proposed to explore these observations in more detail, culminating with cloning the receptor for agrin that regulates the neuronal signal transduction pathway. The results of these studies will contribute to our understanding of neural development and synapse formation in the brain. This knowledge will be directly relevant to the management of brain disorders characterized by cognitive deterioration such as Alzheimer disease, as well as regeneration following traumatic injury.

描述（来自申请人摘要的逐字）：正常的脑功能取决于 高度专业化的神经元之间的信息快速传递 称为突触的结构。了解指导 发育过程中突触的形成及其在成人中的维持 是神经生物学的基本问题我们所知道的大部分 化学突触的发展来自于对 神经肌肉接头，在运动神经元和肌肉接头之间交换信号。 骨骼肌纤维，它们支配运动的协调分化 肌纤维中的神经末梢和突触后器。引人注目 现在有证据表明一种这样的信号是细胞外基质 一种叫做聚集蛋白的分子，在运动神经元诱导的 肌肉纤维中突触成分的组织。相对于 神经肌肉接头，相对较少的是知道的机制， 在中枢神经系统中直接形成神经元-神经元突触。我们有 表明聚集蛋白在哺乳动物脑中表达，与聚集蛋白的作用一致。 聚集蛋白在神经元-神经元突触形成中的作用令人惊讶的是， 聚集蛋白基因敲除小鼠培养的皮质神经元之间的突触发生 似乎正常，提出了什么样的问题，如果有的话，功能agrin服务， 个脑袋 我们已经解决了这个问题，使用表达的立即早期基因c-fos 和神经损伤，以监测神经元活动，并表明缺乏聚集蛋白 培养的皮层神经元对兴奋性氨基酸的敏感性降低 acids.这些研究首次建立了中枢神经系统神经元表型， 在聚集蛋白基因的突变，并提出了聚集蛋白的重要作用， 调节谷氨酸受体表达或功能。实验提出了 试图验证这一假设，并确定细胞缺陷引起的， 突变有证据表明，聚集蛋白是正常发育所必需的， 皮质神经元预测存在神经元信号转导 agrin的途径。初步数据证实了这一假设，表明聚集蛋白 诱导培养的皮质中Fos水平的剂量依赖性饱和增加 神经元生化研究表明，聚集蛋白诱导c-fos是类似的， 但不同于介导聚集蛋白诱导的聚集的信号， 肌肉中的乙酰胆碱受体提出了额外的实验， 更详细地探索这些观察结果，最终克隆了 聚集蛋白的受体，调节神经元信号转导途径。的 这些研究的结果将有助于我们了解神经 发育和突触的形成。这些知识将直接 与以认知功能障碍为特征的脑部疾病的管理相关 退化，如阿尔茨海默病，以及再生后， 外伤