Regulation of Axonal Retrograde Signaling by Palmitoylation

 描述（由申请人提供）：本项目的长期目标是确定轴突中长距离信号传递的分子机制。从远端轴突到神经元核的逆行信号对激活转录程序至关重要， 在神经发育和神经损伤之后。这些逆行信号涉及物理蛋白质转运，但预测几种逆行信号蛋白是可溶性和可扩散的，并且尚不清楚它们如何传递长距离定向信号。该项目旨在测试新的假设，即蛋白质-脂质修饰棕榈酰化允许可溶性信号蛋白在运输囊泡上“搭便车”，从而传递逆行信号。我们的初步研究支持这一假设，并表明，直接棕榈酰化是必不可少的双亮氨酸拉链激酶（DLK）在响应损伤的逆行信号。本提案的目的1将定义这一发现的细胞和分子基础，特别是通过测试棕榈酰化是一种独特的“双重控制”机制，调节DLK定位和激酶活性的新假设。然后，我们将确定棕榈酰化的重要性DLK的“下游”功能的轴突再生损伤后的作用。目的2阐述棕榈酰化如何通过涉及Janus激酶（JAK）和JAK的底物信号转导和转录激活因子3（STAT 3）的第二途径调节信号传导。重要的是，JAK-STAT 3信号传导需要这些蛋白质响应于细胞外刺激而从其稳态位置动态重新定位。因此，这一目标将确定棕榈酰化是否广泛需要逆行信号，也将定义的重要性，刺激依赖性棕榈酰化的动态逆行贩运。目的3旨在鉴定控制逆行信号蛋白棕榈酰化的棕榈酰酰基转移酶（PAT），重点是轴突富集的PAT DHHC 5和DHHC 8是否是JAK/STAT 3的“上游”受体gp 130的关键调节剂。这项提议的总体影响将是定义一种新的分子机制，这对传递轴突逆行信号至关重要。这项工作的重点是对轴突损伤的反应，可能会导致新的疗法，以改善再生生长，而所取得的发现也应该加强我们更广泛的理解轴突发育和神经病理条件与受损轴突贩运。

 DESCRIPTION (provided by applicant): The long-term goal of this project is to define molecular mechanisms by which long-distance signals are conveyed in axons. Retrograde signals from distal axons to neuronal nuclei are critical to activate transcriptional programs both during neurodevelopment and following nerve injury. These retrograde signals involve physical protein transport, but several retrograde signaling proteins are predicted to be soluble and diffusible and it is unclear how they convey long distance directional signals. This project seeks to test the novel hypothesis that the protein-lipid modification palmitoylation allows otherwise soluble signaling proteins to 'hitchhike' on trafficking vesicles and thus convey retrograde signals. Our preliminary studies support this hypothesis and suggest that direct palmitoylation is essential for retrograde signaling by Dual Leucine-zipper Kinase (DLK) in response to injury. Aim 1 of this proposal will define the cellular and molecular basis for this finding, in particularby testing the novel hypothesis that palmitoylation is a unique 'dual control' mechanism that regulates both DLK localization and kinase activity. We will then define the importance of palmitoylation for DLK's 'downstream' functional roles in axonal regeneration post-injury. Aim 2 addresses how palmitoylation regulates signaling by a second pathway involving Janus Kinase (JAK) and JAK's substrate Signal Transducer and Activator of Transcription-3 (STAT3). Importantly, JAK-STAT3 signaling requires dynamic relocalization of these proteins from their steady-state locations in response to extracellular stimuli. This Aim will thus determine whether palmitoylation is broadly required for retrograde signaling and will also define the importance of stimulus-dependent palmitoylation for dynamic retrograde trafficking. Aim 3 seeks to identify the palmitoyl acyltransferases (PATs) that control palmitoylation of retrograde signaling proteins, focusing on whether the axonally-enriched PATs DHHC5 and DHHC8 are key regulators of JAK/STAT3's 'upstream' receptor gp130. The overall impact of this proposal will be to define a novel molecular mechanism that is critical to convey axonal retrograde signals. The focus of this work on responses to axonal injury could lead to new therapies to improve regenerative growth, while the discoveries made should also enhance our broader understanding of axon development and of neuropathological conditions linked to impaired axonal trafficking.