REGULATION OF AXON GUIDANCE MOLECULE GENES: RELEVANCE TO BRAIN ADAPTATION

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。轴突导向分子（Axon guidance molecules，AGM）包括脑信号蛋白、肝配蛋白、netrins及其受体，是神经系统发育和神经适应的重要因素。我们先前证明了成年灵长类动物大脑中存在AGM。目前的研究调查的假设，cAMP的变化可能会促进AGM的基因表达的变化，从而连接药物诱导的神经适应与受体介导的事件。结果如下：采用真实的时间PCR，我们检测了内源性表达的几个AGM和D1多巴胺受体，可卡因的间接目标，在SK-N-MC人神经上皮瘤细胞系。用10 μ M毛喉素（N=5）处理SK-N-MC细胞以增加细胞内cAMP导致测试的14个基因中的EphA 5、EphB 2和神经纤毛蛋白1的表达增加。这3个基因的调节幅度和方向与Bahi和Dreyer（2005）在可卡因后大鼠海马中的发现一致。相反，SK-N-MC细胞暴露于多巴胺受体激动剂dihydrexidine（10 μ M; N=5）导致EphrinA 1的上调和EphrinA 5、EphB 1、DCC和Sema 3C的下调。讨论内容：可以想象，可卡因通过阻断单胺转运蛋白改变AGM表达，从而间接激活单胺受体并改变cAMP产生。AGM基因的表达可能受到cAMP和其他信号转导途径的调节，可能将受体活化与AGM转录调节联系起来。这些初步数据提供了一种新的机制，通过这种机制，药物可以改变AGM的表达，以促进成人大脑中药物诱导的神经适应，这可能与成瘾和药物开发有关。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Axon guidance molecules (AGMs) including semaphorins, ephrins, netrins and their receptors are important contributors to nervous system development and neuroadaptation. We previously demonstrated the presence of AGMs in adult primate brain. The current study investigated the hypothesis that changes in cAMP may promote changes in gene expression of AGMs, thereby linking drug-induced neuroadaptation with receptor-mediated events. Results: Using real time PCR, we detected endogenous expression of several AGMs and the D1 dopamine receptor, an indirect target of cocaine, in the SK-N-MC human neuroepithelioma cell line. Treatment of SK-N-MC cells with 10uM forskolin (N=5) to increase intracellular cAMP resulted in increased expression of EphA5, EphB2 and Neuropilin1, of 14 genes tested. The magnitude and direction of regulation for these 3 genes paralleled the findings of Bahi and Dreyer (2005) in the rat hippocampus after cocaine. In contrast, exposure of SK-N-MC cells to the dopamine receptor agonist dihydrexidine (10uM; N=5) resulted in up-regulation of EphrinA1 and down-regulation of EphrinA5, EphB1, DCC and Sema3C. Discussion: Conceivably, cocaine modifies AGM expression by blocking monoamine transporters, thereby indirectly activating monoamine receptors and altering cAMP production. AGM gene expression may be regulated, in part, by changes in cAMP and other signal transduction pathways, potentially linking receptor activation to AGM transcriptional regulation. These preliminary data offer a novel mechanism by which drugs may modify AGM expression to promote drug-induced neuroadaptation in adult brain which may be of potential relevance to addiction and the development of medications.