Regulation of Axonal Signaling by Palmitoylation

项目摘要 该项目的长期目标是确定控制长距离转移的分子机制。 轴突中的蛋白质信号。逆行（轴突到索马）信号对激活转录调控至关重要。 在神经发育期间和神经损伤后都进行编程，而连续顺行（体细胞到神经） 轴突）供应“轴突存活因子”对于维持远端轴突完整性是必不可少的。我们和其他人发现 传递这些逆行和顺行信号的关键蛋白质被脂质棕榈酸酯修饰， 这有助于它们在轴突囊泡上的运输。特别是，第一个供资周期的试验 揭示了双亮氨酸拉链激酶（DLK，一种上游激活剂（“MAP 3 K”））的逆行信号传导， 促分裂原活化蛋白激酶（MAPK）途径）关键地需要棕榈酰化。我们现在假设 棕榈酰化更广泛地控制轴突信号的几个不同方面。第一个目标将侧重于 JNK家族MAPK的棕榈酰化，其是DLK和其它MAP 3 K下游的关键“效应”激酶。 我们将确定神经特异性JNK 3的棕榈酰化是否是沃勒变性所必需的。 远端轴突，以及JNK 3是否磷酸化棕榈酰化轴突存活因子，触发它们的 通过一种新的磷酸依赖性机制降解。Aim 2将重点关注Rap 2，一种新的棕榈酰化的 调节子，位于DLK的上游，并将决定Rap 2及其棕榈酰化是否广泛存在。 这是DLK依赖性逆行信号传导所必需的。目标3将评估， 与其他蛋白质-脂质修饰相比，棕榈酰化用于促进“寿司带运输” 其中关键的轴突存活因子NMNAT 2经历棕榈酰化依赖的顺行运输， 囊泡，然后局部脱棕榈酰化，以增加其酶和轴突保护活性。拟议 研究将确定棕榈酰化在轴突蛋白运输中的新的细胞和分子作用， 信号，并将提供关键的见解如何响应轴突损伤的协调和控制。 我们的研究结果也可能揭示轴突蛋白质转运和信号传导的更广泛原则， 增加了我们对一系列神经退行性疾病的理解，其中这些过程是 受损

Project Summary The long-term goal of this project is to define molecular mechanisms that govern the long distance transfer of protein-based signals in axons. Retrograde (axon-to-soma) signals are critical to activate transcriptional programs both during neurodevelopment and following nerve injury, while continuous anterograde (soma-to- axon) supply of `axon survival factors' is essential to maintain distal axon integrity. We and others have found that key proteins that convey these retrograde and anterograde signals are modified with the lipid palmitate, which facilitates their trafficking on axonal vesicles. In particular, experiments in the first cycle of funding revealed that retrograde signaling by Dual Leucine-zipper Kinase (DLK, an upstream activator (a `MAP3K') of Mitogen-activated Protein Kinase (MAPK) pathways) critically requires palmitoylation. We now hypothesize that palmitoylation more broadly controls several distinct aspects of axonal signaling. The first Aim will focus on palmitoylation of JNK family MAPKs, which are key `effector' kinases downstream of DLK and other MAP3Ks. We will determine whether palmitoylation of the neural-specific JNK3 is required for Wallerian degeneration of distal axons, and whether JNK3 phosphorylates palmitoylated axon survival factors, triggering their degradation via a novel phospho-dependent mechanism. Aim 2 will focus on Rap2, a novel palmitoylated regulator that lies upstream of DLK, and will determine whether Rap2 and its palmitoylation are broadly required for DLK-dependent retrograde signaling. Aim 3 will assess whether the unique reversibility of palmitoylation, compared with other protein-lipid modifications, is used to facilitate `sushi belt transport' whereby the key axon survival factor NMNAT2 undergoes palmitoylation-dependent anterograde trafficking on vesicles and is then locally depalmitoylated to increase its enzymatic and axo-protective activity. The proposed research will define new cellular and molecular roles for palmitoylation in axonal protein trafficking and signaling and will provide key insights into how responses to axonal damage are coordinated and controlled. Results of our study may also reveal broader principles of axonal protein transport and signaling, in turn increasing our understanding of a range of neurodegenerative disorders in which these processes are impaired.