Regulated degradation of EF2K: linking neuronal protein synthesis and turnover

描述（由申请人提供）：适当的神经元功能需要精确的蛋白质水平时空调节，这主要是通过控制mrna转化为新蛋白质和泛素-蛋白酶体系统（UPS）对现有蛋白质的降解来实现的。使用蛋白质合成药物抑制剂和UPS的研究表明，这些过程对长期突触可塑性和记忆巩固至关重要，这些过程的调节可能涉及介导成瘾发展的大脑奖励系统的可塑性。新出现的证据表明，长期可塑性的稳定需要基因特异性的，而不是全局的，蛋白质合成和降解过程的翻译控制和协调或平衡。这种情况发生的机制，导致的蛋白质表达的特定变化，以及这些过程对药物介导行为的后果是关键问题，本提案试图通过研究真核延伸因子-2激酶（Ca2????）的作用和调节来阐明依赖蛋白激酶，通过磷酸化真核延伸因子-2 （eEF-2）并在延伸阶段抑制翻译来发挥翻译控制作用。先前的研究和初步数据表明，EF2K是基因特异性翻译和蛋白质合成和降解协调的中心介质，尽管这些功能的机制和后果仍有待阐明。为此，本研究将描述EF2K在刺激下以ups介导的降解为目标的机制，EF2K对蛋白质表达模式的具体调控，以及EF2K在可卡因运动致敏中的作用。这些研究将促进对蛋白质合成和降解的基因特异性翻译和协调模式的作用的理解，以及药物滥用介导的可塑性机制，有可能促进新疗法的发展。

DESCRIPTION (provided by applicant): Proper neuronal function requires precise temporal and spatial regulation of protein levels, and this is largely occurs via control over the translation of mRNAs into new proteins and the degradation of existing proteins by the ubiquitin-proteasome system (UPS). Studies using pharmacological inhibitors of protein synthesis and the UPS have indicated that these processes are critical for long-term synaptic plasticity and memory consolidation, and regulation of these processes is likely involved in the plasticity of brain reward systems that mediates the development of addiction. Emerging evidence suggests that stabilization of long-term plasticity requires gene-specific, rather than global, translational control and coordination or balance of protein synthesis and degradation processes. The mechanisms by which this occurs, the specific changes in protein expression that result, and the consequences of these processes for drug-mediated behavior are critical issues that this proposal seeks to elucidate by investigating the role and regulation of eukaryotic elongation factor-2 kinase, a Ca2????dependent protein kinase that exerts translational control by phosphorylating eukaryotic elongation factor-2 (eEF-2) and inhibiting translation at the elongation step. Previous studies and preliminary data suggest that EF2K is a central mediator both of gene-specific translation and the coordination of protein synthesis and degradation, although the mechanisms and consequences of these functions remain to be elucidated. To this end, the proposed research will characterize the mechanisms by which EF2K is targeted for UPS-mediated degradation in response to stimulation, the specific regulation that EF2K exerts on patterns of protein expression, and the role of EF2K in locomotor sensitization to cocaine. These studies will advance understanding of the role of gene-specific modes of translation and coordination of protein synthesis and degradation, as well as the mechanisms of plasticity mediated by drugs of abuse, potentially enabling the development of novel therapeutics. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to characterize the function of gene-specific translational control and coordination of protein synthesis and degradation in cocaine-mediated behavior, the mechanisms by which these processes occur, and their specific consequences for patterns of protein expression. The long-term changes in neural reward circuitry that underlie addiction are thought to engage these molecular processes, and by characterizing them in detail, novel approaches to the treatment of addiction may be developed.