Protein Kinase C Isozymes in Hippocampal Plasticity

海马可塑性中的蛋白激酶 C 同工酶

• 批准号: 7171515
• 负责人: TODD C SACKTOR
• 金额: $ 32.64万
• 依托单位: SUNY DOWNSTATE MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7171515
• 关键词: 1-Phosphatidylinositol 3-Kinase; 5' Untranslated Regions; Brain; C-terminal; Catalytic Domain; Cell model; Complex; Cyclic AMP-Dependent Protein Kinases; Data; Dendrites; Enzymes; Exons; Felis catus; Figs - dietary; Genes; Genetic Transcription; Glutamates; Goals; Hippocampus (Brain); Immune Sera; Isoenzymes; Left; Long-Term Potentiation; Maintenance; Mediating; Membrane; Memory; Messenger RNA; Mitogen-Activated Protein Kinases; Modeling; Modification; N-terminal; Neurotransmitters; Pathway interactions; Phase; Phosphoinositide-3-Kinase, Catalytic, Gamma Polypeptide; Phosphorylation; Phosphotransferases; Physiological; Principal Investigator; Production; Protein Dephosphorylation; Protein Kinase C; Proteins; Proteolysis; Pyramidal Cells; Regulation; Research Personnel; Role; Second Messenger Systems; Signal Pathway; Sirolimus; Site; Synapses; Synaptic Transmission; Testing; Tetanus; Thinking; Time; Transcription Initiation Site; Transcriptional Regulation; Translational Repression; Translations; Untranslated Regions; Work; base; inhibitor/antagonist; programs; promoter; second messenger

DESCRIPTION (provided by applicant): Long-term changes in synaptic strength are thought to contribute to the cellular basis of memory. These changes can be divided into two phases: a brief induction, triggering the modification, and a persistent maintenance, sustaining it over time. We have found a new form of atypical PKC, called PKMzeta, increases during the maintenance of long-term potentiation (LTP), a widely studied, putative cellular model of memory. PKC is usually held in an inactive state because its regulatory domain inhibits its catalytic domain; second messengers activate the enzyme by transiently releasing this autoinhibition. In contrast, PKMzeta is an independent PKC catalytic domain and, lacking the inhibition from a regulatory domain, is autonomously active. We found that increased function of PKMzeta is sufficient to enhance synaptic transmission when the kinase is introduced into CA1 pyramidal cells. The persistently increased activity of PKMzeta is also necessary for maintenance, because specific inhibitors of PKMzeta reverse established LTP. Our overall goal then is to elucidate the physiological mechanisms that increase PKMzeta function in LTP maintenance. The 1st aim is to examine posttranslational mechanisms for increasing PKMzeta function. Preliminary data suggest that PKMzeta is phosphorylated through the PI3-kinase/PDKl pathway. Using phosphorylation state-specific antisera to PKMzeta, we will test the hypotheses that this modification increases PKMzeta's function in LTP and dephosphorylation of this site decreases its activity in LTD. The 2nd aim is to determine the translational mechanisms for increasing PKMzeta function. PKM, the independent catalytic domain of PKC, is usually thought of as a proteolytic fragment of PKC. Our preliminary data, however, show that brain PKMzeta, is formed physiologically, not by proteolysis, but by translation of a brain-specific PKMzeta mRNA. This PKMzeta, mRNA is targeted to dendrites, and we will examine the regulation of increased local translation by the MAP-kinase and rapamycin-sensitive pathways. The 3rd aim examines the transcriptional mechanisms for increasing PKMzeta function. New data indicate that increased PKMzeta function is critical for late LTP. We find that an internal promoter within the PKCS, gene transcribes the PKMzeta mRNA. A long 5'untranslated region (5'UTR) on some PKMzeta mRNAs inhibits its translation. Regulation of the PKMzeta transcription start site during LTP may produce PKMC, mRNAs with shorter 5'UTRs, thus increasing the message's translational capacity and providing a long-term mechanism for maintaining increased PKMzeta function. These 3 goals aim to understand in mechanistic detail the physiological increase of PKMzeta function in LTP maintenance, which might help provide a unifying framework for the complex signaling pathways of memory.

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细胞基础。这些变化可以分为两个阶段：短暂的归纳，触发修改，以及持久的维护，随着时间的推移维持它。我们发现一种新形式的非典型 PKC，称为 PKMzeta，在长期增强 (LTP) 的维持过程中增加，LTP 是一种广泛研究的假定细胞记忆模型。 PKC 通常处于非活性状态，因为其调节域抑制其催化域；第二信使通过暂时释放这种自抑制来激活酶。相比之下，PKMzeta 是一个独立的 PKC 催化结构域，缺乏调节结构域的抑制，具有自主活性。我们发现，当将激酶引入 CA1 锥体细胞时，PKMzeta 功能的增强足以增强突触传递。 PKMzeta 活性的持续增加对于维持也是必要的，因为 PKMzeta 的特异性抑制剂会逆转已建立的 LTP。 我们的总体目标是阐明在 LTP 维持中增加 PKMzeta 功能的生理机制。第一个目标是检查增强 PKMzeta 功能的翻译后机制。初步数据表明 PKMzeta 通过 PI3 激酶/PDK1 途径被磷酸化。使用针对 PKMzeta 的磷酸化状态特异性抗血清，我们将测试以下假设：这种修饰会增加 PKMzeta 在 LTP 中的功能，而该位点的去磷酸化则会降低其在 LTD 中的活性。第二个目标是确定增加 PKMzeta 功能的翻译机制。 PKM是PKC的独立催化结构域，通常被认为是PKC的蛋白水解片段。然而，我们的初步数据表明，大脑 PKMzeta 是通过生理学形成的，不是通过蛋白水解，而是通过大脑特异性 PKMzeta mRNA 的翻译。该 PKMzeta mRNA 靶向树突，我们将检查 MAP 激酶和雷帕霉素敏感途径对增加的局部翻译的调节。第三个目标是检查增强 PKMzeta 功能的转录机制。新数据表明 PKMzeta 功能的增强对于晚期 LTP 至关重要。我们发现 PKCS 基因内的内部启动子转录 PKMzeta mRNA。一些 PKMzeta mRNA 上的长 5' 非翻译区 (5'UTR) 会抑制其翻译。 LTP 期间 PKMzeta 转录起始位点的调节可能会产生 PKMC，即具有较短 5'UTR 的 mRNA，从而增加信息的翻译能力，并为维持增强的 PKMzeta 功能提供长期机制。这 3 个目标旨在详细了解 PKMzeta 功能在 LTP 维持中的生理增强，这可能有助于为复杂的记忆信号通路提供统一的框架。