Drug abuse signaling pathways that regulate CREB mRNA translation in dendrites

描述（由申请人提供）：拟议研究的目的是了解滥用药物的突触刺激如何导致细胞核中的转录效应。所有滥用的药物都被证明会刺激基因表达的变化。这些变化被认为是反复暴露于药物后出现的许多长期变化的基础，这些变化是成瘾的特征。然而，目前还不清楚突触上的信号如何影响细胞核中的基因转录，细胞核之间的距离可以达到几百微米。我们最近发现，编码CREB（一种转录因子）的mRNA存在于发育中神经元的轴突和生长锥中，并且该mRNA在暴露于NGF时“局部”翻译，导致CREB在生长锥中积累，然后磷酸化并逆行运输到细胞核。这种轴突来源的CREB与启动子序列结合并刺激神经元存活所必需的基因转录。因此，生长锥至细胞核信号传导需要局部翻译和逆行运输。除了其在神经元存活中的作用之外，CREB在介导与药物滥用相关的长期变化中具有关键作用。我们的初步数据表明，CREB是在树突内翻译。在这个应用程序中，我们提出的实验，以确定药物滥用相关的突触信号通路，调节树突CREB的翻译，磷酸化和核转位。此外，使用神经元选择性缺乏树突状CREB mRNA，我们将确定树突状CREB mRNA在核基因转录中的作用。总之，CEBRA应用中的实验将探索这种意想不到的信号传导模式的作用，这将显著影响我们目前对滥用药物分子机制的思考。

DESCRIPTION (provided by applicant): The objective of the proposed research is to understand how synaptic stimulation by drugs of abuse leads to transcriptional effects in the nucleus. All drugs of abuse have been shown to stimulate changes in gene expression. These changes are thought to underlie many of the long-term changes seen following repeated drug exposure that characterize addiction. However, it is unclear how signaling at a synapse could affect gene transcription in the nucleus, which can be separated by a distance of several hundred micrometers. We have recently discovered that the mRNA encoding CREB, a transcription factor, is present in the axons and growth cones of developing neurons, and this mRNA is translated 'locally' upon exposure to NGF, resulting in the accumulation of CREB in growth cones, which is then phosphorylated and retrogradely trafficked to the nucleus. This axonally-derived CREB binds to promoter sequences and stimulates the gene transcription necessary for neuronal survival. Thus, local translation and retrograde trafficking is required for growth cone- to-nucleus signaling. In addition to its role in neuronal survival, CREB has critical roles in mediating the long- term changes associated with drugs of abuse. Our preliminary data show that CREB is translated within dendrites. In this application, we propose experiments to identify drug abuse-related synaptic signaling pathways that regulate dendritic CREB translation, phosphorylation, and nuclear translocation. Furthermore, using neurons selectively-deficient in dendritic CREB mRNA, we will determine the role of dendritic CREB mRNA in nuclear gene transcription. Together, the experiments in this CEBRA application will explore the role of this unanticipated mode of signaling which would significantly impact our current thinking about the molecular mechanisms employed by drugs of abuse.