REGULATED PROTEOLYSIS AND LONG-TERM MEMORY

调控蛋白水解和长期记忆

• 批准号: 6204734
• 负责人: ASHOK N HEGDE
• 金额: $ 8.97万
• 依托单位: NEW YORK STATE PSYCHIATRIC INSTITUTE DBA RESEARCH FOUNDATION FOR MENTAL HYGIENE, INC
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2001-01-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6204734
• 关键词: biological signal transduction; cAMP response element binding protein; electrophysiology; immunocytochemistry; laboratory rabbit; long term memory; neural facilitation; neural plasticity; proteasome; proteolysis; ubiquitin

Study of synaptic plasticity is not only important for understanding normal brain function such as learning and memory but also is necessary for identifying the underlying causes of many neurological and mental diseases. A tractable model system for investigating synaptic plasticity is long-term presynaptic facilitation of sensory-to-motor neuron synapses in Aplysia, an elementary form of learning and memory. Long-term facilitation requires signal transduction from the neurotransmitter 5-HT to the nucleus for activation of gene transcription by the cAMP- responsive element binding protein (CREB). All along the signaling pathway inhibitors operate to prevent memory formation in the absence of adequate stimuli. These inhibitors are degraded by the ubiquitin-proteasome pathway. Our overall goal is to determine how the ubiquitin-proteasome pathway functions to remove proteins that inhibit long-term facilitation and to understand the important regulatory checkpoints in this pathway. An earlier discovery showed that the regulatory subunit of the cAMP-dependent protein kinase is degraded by the ubiquitin pathway to make the kinase persistently active. Our hypothesis is that modulation of the regulatory complexes attached to the enzymatic core of the proteasome contributes to the increased degradation of R subunits and other substrates. Our recent preliminary data indicate that two subunits of the regulatory part of the proteasome play a critical role in the formation of long-term facilitation. We also have direct evidence for removal of CREB 1b, a CREB repressor, by the ubiquitin-proteasome pathway. The proteolysis of CREB 1b occurs during a time window preceding CREB activation. Our results indicate that the activity of the enzyme that targets CREB lb for proteolytic removal is regulated by phosphorylation. Our first aim is to show that the up-regulation of two proteasome regulatory subunits plays an important role in induction of long-term facilitation. Our second aim is to isolate and study the enzyme that targets CREB 1b for degradation and to demonstrate that it plays a critical role in inducing long-term facilitation. The concept that the ubiquitin-proteasome pathway operates to determine the threshold for gene induction by CREB and consequently threshold for formation of long-term memory could be widely applicable to understanding other forms of neuronal plasticity. Our approach that uses a combination of molecular, cellular and electrophysiological techniques would enable us to gain novel insights into the mechanisms underlying synaptic plasticity. Since alterations in CREB activation as well as the ubiquitin- proteasome pathway are seen in several abnormalities of the brain, these insights would be useful for identifying the causes of neuronal dysfunction as well as designing therapeutic interventions.

突触可塑性的研究不仅对于理解学习和记忆等正常大脑功能很重要，而且对于确定许多神经和精神疾病的根本原因也是必要的。 用于研究突触可塑性的易于处理的模型系统是海兔（学习和记忆的基本形式）中感觉运动神经元突触的长期突触前促进。 长期促进需要从神经递质 5-HT 到细胞核的信号转导，以通过 cAMP 反应元件结合蛋白 (CREB) 激活基因转录。 在缺乏足够刺激的情况下，信号通路抑制剂一直在阻止记忆形成。 这些抑制剂通过泛素-蛋白酶体途径降解。 我们的总体目标是确定泛素-蛋白酶体途径如何发挥作用以去除抑制长期促进的蛋白质，并了解该途径中的重要监管检查点。较早的发现表明，cAMP依赖性蛋白激酶的调节亚基被泛素途径降解，使激酶持续活跃。 我们的假设是，调节连接到蛋白酶体酶核心的调节复合物有助于增加 R 亚基和其他底物的降解。 我们最近的初步数据表明，蛋白酶体调节部分的两个亚基在长期促进的形成中发挥着关键作用。 我们还有直接证据表明 CREB ​​1b（一种 CREB ​​阻遏蛋白）通过泛素-蛋白酶体途径被去除。 CREB ​​1b 的蛋白水解发生在 CREB ​​激活之前的时间窗口内。 我们的结果表明，靶向CREB ​​1b进行蛋白水解去除的酶的活性受到磷酸化的调节。 我们的第一个目标是证明两个蛋白酶体调节亚基的上调在诱导长期促进中发挥重要作用。我们的第二个目标是分离和研究以 CREB ​​1b 为目标进行降解的酶，并证明它在诱导长期促进作用中发挥着关键作用。 泛素-蛋白酶体通路的作用是确定 CREB ​​基因诱导的阈值，从而确定长期记忆形成的阈值，这一概念可广泛应用于理解其他形式的神经元可塑性。 我们的方法结合了分子、细胞和电生理学技术，将使我们能够对突触可塑性的机制获得新的见解。由于 CREB ​​激活以及泛素-蛋白酶体通路的改变在大脑的几种异常中可见，因此这些见解将有助于确定神经元功能障碍的原因以及设计治疗干预措施。