Regulation of Axonal Retrograde Signaling by Palmitoylation

 描述(申请人提供)：该项目的长期目标是确定长距离信号在轴突中传递的分子机制。从远端轴突到神经元核团的逆行信号是激活转录程序的关键 在神经发育期间和神经损伤后。这些逆行信号涉及物理蛋白质运输，但几种逆行信号蛋白被预测为可溶和可扩散的，目前尚不清楚它们如何传递长距离定向信号。这个项目试图验证这个新的假说，即蛋白质-脂质修饰棕榈酸化允许原本可溶的信号蛋白搭乘运输小泡的‘便车’，从而传递逆行信号。我们的初步研究支持这一假说，并表明直接棕榈酰化对于双重亮氨酸拉链激酶(DLK)在损伤反应中的逆行信号转导至关重要。这项建议的目标1将定义这一发现的细胞和分子基础，特别是通过检验棕榈酰化是调节DLK定位和激酶活性的独特的“双重控制”机制这一新假设。然后，我们将确定棕榈酰化对于DLK在损伤后轴突再生中的“下游”功能作用的重要性。目的2研究棕榈酰化如何通过涉及Janus Kinase(JAK)和JAK底物信号转导和转录激活因子-3(STAT3)的第二条途径来调节信号传导。重要的是，JAK-STAT3信号需要这些蛋白在细胞外刺激下从其稳定位置动态重新定位。因此，这一目标将决定棕榈酰化是否广泛地需要用于逆行信号传递，并将确定依赖于刺激的棕榈酰化对于动态逆行贩运的重要性。目的鉴定控制逆行信号蛋白棕榈酰化的棕榈酰酰基转移酶(PATS)，重点研究轴向富集型PATS DHHC5和DHHC8是否是JAK/STAT3‘上游’S‘受体gp130的关键调节因子。这项提议的总体影响将是定义一种新的分子机制，该机制对于传递轴突逆行信号至关重要。这项工作的重点是轴突损伤的反应，这可能会导致新的治疗方法来改善再生生长，同时所做的发现也应该加强我们对轴突发育和与轴突运输受损相关的神经病理状况的更广泛的理解。

 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.