Regulation of parallel recycling pathways at synaptic sites

项目摘要/摘要 肌醇磷脂信号脂是膜内转运的关键调节者，对突触至关重要 功能性和可塑性。值得注意的是，许多突触特有的运输途径与同源基因高度相似 非神经细胞中的通路。突触的专门交易很大程度上是通过适度的 对通用贩运路径的更改。由于突触的高流量需求，非常微小的突变 在这些途径中，特别影响神经系统，并导致广泛的神经系统疾病。 PIKfyve及其调控蛋白Vac14和Fig4控制低丰度的细胞水平 信号脂磷脂酰肌醇(3，5)-双磷酸(PI3，5P2)和磷脂酰肌醇5-磷酸 (PI5P)。我们和其他人的研究表明，这一途径中的微小突变与几个 神经紊乱。对PI(3，5)P2在神经元中的作用的深入了解来自我们对PIKfyve所起作用的发现 在突触功能和可塑性中起重要作用，并部分通过控制AMPA的表面水平起作用。 型谷氨酸受体(AMPAR)。PIKfyve下调调节导致循环和表面水平的提高 虽然其潜在的分子机制(S)尚不清楚。矛盾的是，我们的新研究 非神经细胞，揭示了PIKfyve在SNX17循环途径的控制中具有直接的积极作用。 值得注意的是，SNX17和SNX27通路都来自内小体上的相同微域。这 将PIKfyve放在主动回收依赖SNX17和SNX27的货物的内体上。 重要的是，AMPAR表面水平在一定程度上是通过SNX27依赖的循环来控制的。本提案的目标1 试图确定PIKfyve是否通过对SNX27的负调控来控制AMPAR表面水平- 依赖回收。 重要的是，我们的新研究提出了SNX17在PIKfyve抑制过程中调节失调的可能性， 也可能导致观察到的突触缺陷。SNX17功能蛋白的突变是其基础 一些神经系统疾病，但令人惊讶的是，还没有发表的研究来确定SNX17 再循环对突触功能至关重要。目前的项目将测试PIKfyve不同的假设 调节来自相同内体的不同循环途径。为了解决这一假设，我们 将1)确定PIKfyve调节AMPAR循环的机制；2)确定SNX17- 无论是否类似于非神经细胞，PIKfyve都是这一通路的调节者。

PROJECT SUMMARY/ABSTRACT Phosphoinositide signaling lipids are key regulators of endomembrane trafficking and are critical for synaptic function and plasticity. Notably, many synapse-specific trafficking pathways are highly similar to cognate pathways in non-neuronal cells. The specialized trafficking at synapses is largely achieved via modest alterations to generic trafficking pathways. Due to the high demand of traffic at synapses, very minor mutations in these pathways specifically impact the nervous system and underlie a wide range of neurological disorders. PIKfyve and its regulatory proteins Vac14 and Fig4 control the cellular levels of the low abundance signaling lipids phosphatidylinositol (3,5)-bis phosphate (PI3,5P2) and phosphatidylinositol 5- phosphate (PI5P). Studies from us and others revealed that minor mutations in this pathway are associated with several neurological disorders. Insights into roles of PI(3,5)P2 in neurons came from our discovery that PIKfyve plays essential roles in synaptic function and plasticity, and acts in part via controlling the surface levels of AMPA- type glutamate receptors (AMPARs). PIKfyve downregulation results in enhanced recycling and surface levels of AMPAR, although the underlying molecular mechanism(s) are unknown. Paradoxically, our new studies in non-neuronal cells, reveal that PIKfyve has a direct positive role in the control of the SNX17 recycling pathway. Notably, both the SNX17 and SNX27 pathways emerge from the same microdomains on endosomes. This places PIKfyve on endosomes that actively recycle both SNX17-dependent and SNX27-dependent cargoes. Importantly AMPAR surface levels are controlled in part via SNX27-dependent recycling. Aim 1 of this proposal seeks to determine whether PIKfyve controls AMPAR surface levels via negative regulation of SNX27- dependent recycling. Importantly, our new studies raise the possibility that dysregulation of SNX17 during PIKfyve inhibition, may also contribute to the observed synaptic defects. Mutations in proteins that function with SNX17 underlie some neurological diseases, but surprisingly, there are no published studies to establish whether SNX17 recycling is critical for synaptic function. The current project will test the hypothesis that PIKfyve differentially regulates distinct recycling pathways that emerge from the same endosomes. To address this hypothesis we will 1) Determine mechanisms whereby PIKfyve regulates AMPAR recycling; 2) Determine roles of the SNX17- Retriever pathway in neurons and whether similar to non-neuronal cells, PIKfyve is a regulator of this pathway.