Regulation of Neural Function of Atypical PKC

非典型PKC的神经功能调节

• 批准号: 7150665
• 负责人: TODD C SACKTOR
• 金额: $ 32.73万
• 依托单位: SUNY DOWNSTATE MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-04-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7150665
• 关键词: AMPA receptors; behavior test; enzyme activity; enzyme induction /repression; enzyme inhibitors; gene expression; genetically modified animals; glutamate receptor; hippocampus; isozymes; laboratory mouse; laboratory rat; long term memory; long term potentiation; neural inhibition; neural plasticity; neural transmission; protein kinase C; protein localization; protein structure function; protein transport; pyramidal cells; stimulus /response; synapses; tissue /cell preparation

DESCRIPTION (provided by applicant): Long-term changes of synaptic strength are thought to contribute to the underlying physiological substrate of memory. The molecular mechanisms mediating this plasticity can be divided into 2 phases: induction, triggering the change, and maintenance, sustaining it over time. One model to study these mechanisms is a long-term increase in synaptic strength induced by afferent tetanic stimulation, called long-term potentiation (LTP). Whereas the signaling pathways of LTP induction are exceedingly complex, much less is known about LTP maintenance. These maintenance mechanisms, however, may underlie memory storage. Our laboratory has focused on protein kinase C (PKC) in LTP maintenance. By examining the complete PKC isoform family, we identified a new PKC isoform, called PKMzeta, which persistently increases in LTP maintenance. Most PKCs consist of an N-terminal autoinhibitory regulatory domain and a C-terminal catalytic domain; second messengers activate PKC by releasing this intramolecular autoinhibition. PKMzeta, in contrast, is the independent catalytic domain of the atypical PKCzeta isoform, and, lacking a regulatory domain, is constitutively active. In Work Accomplished, we found whole-cell perfusion of PKMzeta into CA1 pyramidal cells potentiates AMPA receptor-mediated synaptic transmission. Furthermore, PKMzeta inhibitors reverse established LTP. Thus our overall goal now is to elucidate the mechanisms of PKMzeta function. Our 1st Aim is to determine the receptors mediating PKMzeta enhancement of excitatory synaptic transmission. AMPARs are composed of subunits, GluR1-4; we will use knock-out mice for each subunit to determine the subunit targets of AMPAR potentiation by PKMzeta. Our 2nd aim is to examine the molecular mechanisms of PKMzeta-mediated synaptic enhancement. Preliminary data indicate that PKMzeta increases the number of postsynaptic AMPARs through interaction between the GluR2 subunit and a critical AMPAR- trafficking protein called NSF (N-ethylmaleimide sensitive fusion protein). Our 3rd aim is to define the phase of LTP maintained by synaptically activated PKMzeta and to begin to determine the kinase's role in hippocampus-dependent spatial memory. These 3 aims will elucidate the function of PKMzeta and might provide core molecular mechanisms for maintaining long-term synaptic plasticity. These mechanisms may be important for both normal memory storage and memory dysfunction in amnestic disorders.

描述（由申请人提供）：突触强度的长期变化被认为有助于记忆的潜在生理基础。介导这种可塑性的分子机制可以分为两个阶段：诱导，触发变化，以及维持，随着时间的推移维持变化。研究这些机制的一种模型是由传入强直刺激引起的突触强度的长期增加，称为长时程增强（LTP）。尽管 LTP 诱导的信号通路极其复杂，但人们对 LTP 维持的了解却少之又少。然而，这些维护机制可能是内存存储的基础。我们的实验室专注于 LTP 维持中的蛋白激酶 C (PKC)。通过检查完整的 PKC 同工型家族，我们发现了一种新的 PKC 同工型，称为 PKMzeta，它的 LTP 维持持续增加。大多数 PKC 由 N 端自抑制调节结构域和 C 端催化结构域组成；第二信使通过释放这种分子内自动抑制来激活 PKC。相比之下，PKMzeta 是非典型 PKCzeta 亚型的独立催化结构域，并且缺乏调节结构域，具有组成型活性。在 Work Accomplished 中，我们发现将 PKMzeta 全细胞灌注到 CA1 锥体细胞中可增强 AMPA 受体介导的突触传递。此外，PKMzeta 抑制剂可逆转已建立的 LTP。因此，我们现在的总体目标是阐明 PKMzeta 功能的机制。我们的第一个目标是确定介导 PKMzeta 增强兴奋性突触传递的受体。 AMPAR 由亚基 GluR1-4 组成；我们将使用每个亚基的敲除小鼠来确定 PKMzeta 增强 AMPAR 的亚基目标。我们的第二个目标是研究 PKMzeta 介导的突触增强的分子机制。初步数据表明，PKMzeta 通过 GluR2 亚基和称为 NSF（N-乙基马来酰亚胺敏感融合蛋白）的关键 AMPAR 运输蛋白之间的相互作用增加突触后 AMPAR 的数量。我们的第三个目标是定义由突触激活的 PKMzeta 维持的 LTP 阶段，并开始确定该激酶在海马依赖性空间记忆中的作用。这三个目标将阐明 PKMzeta 的功能，并可能提供维持长期突触可塑性的核心分子机制。这些机制对于正常的记忆存储和遗忘症的记忆功能障碍可能都很重要。