The role of a novel viral-like signalling pathway in synaptic plasticity and neurological disorders

我们发现了一种新的病毒样信号通路与细胞外囊泡（EV）。我们 发现了果蝇ARC（肌动蛋白调节的细胞凋亡相关蛋白）（darc 1）的同源物， 存在于EV中的mRNA和蛋白质。ARC是神经系统中突触可塑性的主要调节器， 哺乳动物的神经系统，对学习和记忆至关重要。dArc 1具有类似于 逆转录病毒/逆转录转座子GAG样蛋白，其多聚化成包装病毒RNA的衣壳。我们 研究表明，dARC 1形成衣壳，与自己的RNA结合，然后运输darc 1转录本 穿过突触dArc 1的转移是在飞行中依赖于活动的可塑性所必需的 神经肌肉接头（NMJ）。除了dArc 1，还不知道是否有其他基因在这种病毒样 通路我们在目标1中解决了这种不确定性。在这里，我们描述了我们的计划，以确定其他类似加格 我们已经发现了另一种在EV中富集的Gag蛋白，它是由 反转录转座子Copia。我们已经发现Copia在突触终扣上传递。当copia是 在NMJ处被击倒，这显著地导致了可塑性的增加。这与darc 1相反， 我们报告了可塑性的下降。在目标2中，我们关注哪些货物与dArc 1共同转移， 科皮亚我们已经通过免疫共沉淀鉴定了与dArc 1相关的mRNA和蛋白质， 和Copia。至于Arc的转移是如何发生的，我们发现dArc 1 3 '非翻译区（UTR） 是dArc 1跨突触终扣传递的必要和充分条件。我们现在正在测试， dArc 1 3 'UTR指导dArc 1加载到EV中。同时，我们提出实验来了解如何 darc 1和copia介导突触可塑性。我们共免疫沉淀dArc 1和Copia， 潜在的相互作用者，我们将采取候选方法来寻找遗传相互作用者。在初步工作中 我们发现dArc 1是NMJ上适当的WNT通路信号传导所必需的。此外，我们观察到 Copia和dArc 1与一些相同的蛋白质和mRNA结合，这表明它们可能是 相互对立，从而潜在地解释了它们在调节可塑性方面似乎相反的作用。 通过这项资助，我们将扩大我们对EV运输和突触可塑性的理解， 描述了反转录转座子在神经元通讯中的新的生理功能。

We have discovered a novel viral-like signaling pathway associated with extracellular vesicles (EV). We found the Drosophila homolog of ARC (Actin-Regulated Cytoskeleton-associated protein) (darc1), is present in EVs as both an mRNA and protein. ARC is a master regulator of synaptic plasticity in the nervous system of mammals and is crucial for learning and memory. dArc1 bears a domain resembling retroviral/retrotransposon Gag-like proteins that multimerizes into a capsid that packages viral RNA. Our work shows dARC1 forms a capsid, associates with its own RNA, and then transports the darc1 transcript across the synapse. The transfer of dArc1 is needed for activity-dependent plasticity at the fly neuromuscular junction (NMJ). Besides dArc1, it is unknown whether other genes are in this viral-like pathway. We address this uncertainty in Aim 1. Here we describe our plan to identify other Gag-like proteins in EVs, and we have already found another Gag protein enriched in EVs, that is encoded by the retrotransposon Copia. We have found that Copia transfers across the synaptic bouton. When copia is knocked down at the NMJ this strikingly leads to increased plasticity. This is the opposite of darc1, where we reported a decrease in plasticity. In Aim 2 we focus on what cargoes are co-transferring with dArc1 and Copia. We have identified through co-immunoprecipitation, mRNAs and proteins that associate with dArc1 and Copia. As to how the transfer of Arc occurs, we have found that the dArc1 3’untranslated region (UTR) is necessary and sufficient for the transfer of dArc1 across synaptic boutons. We are now testing if the dArc1 3’UTR directs the loading of dArc1 into EVs. As well, we propose experiments to understand how darc1 and copia mediate synaptic plasticity. We have co-immunoprecipitated dArc1 and Copia to identify potential interactors, and we will take a candidate approach to find genetic interactors. In preliminary work we found that dArc1 is needed for proper WNT pathway signaling at the NMJ. Additionally, we observe that Copia and dArc1 bind to some of the same proteins and mRNAs, suggesting that they may be antagonistic to each other, thus potentially explaining their seemingly opposite roles in mediating plasticity. Through this grant we will expand our understanding of EV trafficking and synaptic plasticity, while describing a novel physiological function of a retrotransposon in neuronal communication.