Role of Stress Granule Protein Aggregation in Axon Regeneration

应激颗粒蛋白聚集在轴突再生中的作用

基本信息

批准号：
10265401
负责人：
JEFFERY L TWISS
金额：
$ 53.42万
依托单位：
UNIVERSITY OF SOUTH CAROLINA AT COLUMBIA
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2025-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10265401
关键词：
Acute Address Adult Affect Attenuated Automobile Driving Axon Axotomy Binding Biological Cells Chronic Clinical Communities Complex Cytoplasmic Granules Data FRAP1 gene G3BP1 gene Genetic Translation Growth Growth Associated Protein 43 Hour Human Importins In Vitro Individual Injury Knowledge Lesion Literature Messenger RNA Molecular Motor Natural regeneration Nerve Nerve Regeneration Neuraxis Neurons Neurosciences Pathway interactions Peptides Peripheral Peripheral Nerves Peripheral Nervous System Peripheral nerve injury Permeability Phosphorylation Phosphotransferases Physiological Population Protein Biosynthesis Proteins Publishing RNA RNA, Messenger, Stored Regenerative capacity Regulation Reporting Research Role Sensory Signal Transduction Solid Specificity Spinal Cord Spinal cord injury Tertiary Protein Structure Testing Therapeutic Time Tissues Translating Translational Activation Translations Viral Work axon growth axon injury axon regeneration calreticulin casein kinase clinically relevant cohort in vivo injured injury and repair insight knock-down nerve injury neuromechanism novel therapeutic intervention overexpression programs protein aggregation recruit reinnervation relating to nervous system repaired response to injury stress granule tool

项目摘要

Peripheral nerves spontaneously regenerate but the axon growth rate is abysmally slow, such that complete functional reinnervation of targets is rarely achieved in humans. Axon regeneration in the central nervous system is even worse, such that individuals with spinal cord injury (SCI) almost invariably have permanent lose of sensory and motor functions below the level of the lesion. There is a pressing need to accelerate axon regeneration in the peripheral nervous system and increase axon regeneration in the central nervous system. Our research program focuses on axon intrinsic mechanisms of regeneration. Intra-axonally synthesized proteins support axon growth in developing neurons. We have shown that PNS neurons retain the capacity to synthesize proteins in their axons and these proteins support growth of injured axons. Axons of cultured neurons contain thousands of mRNAs – and several lines of evidence point to complex populations of mRNAs in CNS axons in vivo and spinal cord axons contain mRNAs and translational machinery when encouraged to regenerate with permissive substrates. Despite remarkable advances since the early 2000’s, the molecular mechanisms that determine when and where a specific mRNA is translated in axons remain largely unknown. This level of regulation is critical for regulating axon growth capacity. We have shown that mRNAs are stored in PNS axons in RNA-protein aggregates that contain the stress granule protein G3BP1. G3BP1 protein can drive stress granule aggregation, and G3BP1 phosphorylation blocks stress granule assembly. Unlike the classically defined stress granule, axonal G3PB1 protein shows aggregation in uninjured/functioning PNS axons. These axonal G3BP1 aggregates rapidly increase after axotomy, but decrease to below basal levels shortly thereafter with a corresponding increase in phosphorylated G3BP1. G3BP1 binds to mRNAs in axons and attenuates their translation. We have discovered exogenous agents and endogenous signals that trigger disassembly of axonal G3BP1 aggregates. The exogenous agents specifically increase axonal protein synthesis and accelerate axon growth rates in vitro and in vivo. These observations have led us to hypothesize that physiological aggregation of stress granule proteins in axons attenuates axon growth in the injured PNS and CNS by blocking translation of an axonal mRNA cohort. We will test this hypothesis with the following specific aims: Aim 1 – Promotion of axon growth by inhibition of G3BP1 function. Aim 2 – Endogenous mechanisms for axonal G3BP1 aggregate disassembly. Aim 3 – Mechanisms driving axon growth upon disassembly of axonal G3BP1 aggregates. Functional roles for axonal translation have now come to light and we have solid in vivo evidence that this mechanism can be targeted to accelerate axon growth after acute peripheral nerve injury. Completion of the proposed research will bring new insight into mechanisms for temporal regulation of axonal mRNA translation in axon injury & regeneration and uncover new therapeutic strategies for neural repair.

周围神经自发再生，但轴突生长速率速度较慢，以至于在人类中，很少实现目标的完全功能性接触。轴突再生中枢神经系统甚至更糟，因此脊髓损伤的人（SCI）几乎总是在病变水平以下的感觉和运动功能的永久丧失。在周围神经系统中加速轴突再生的迫切需要增加中枢神经系统中的轴突再生。我们的研究计划着重于轴突再生的内在机制。轴内合成的蛋白支持轴突在发展神经元。我们已经表明，PNS神经元保留合成蛋白质的能力它们的轴突和这些蛋白支持受伤的轴突的生长。培养神经元的轴突包含成千上万的mRNA - 有几条证据表明CNS中mRNA的复杂种群鼓励体内轴突和脊髓轴突包含mRNA和翻译机械。用允许的底物再生。尽管自2000年代初以来的显着进步，确定何时何地的分子机制特定的mRNA被翻译成轴突，但基本上未知。这种法规是对调节轴突增长能力至关重要。我们已经证明mRNA存储在PNS轴突中含有应力颗粒蛋白G3BP1的RNA蛋白聚集体。 G3BP1蛋白可以驱动应力颗粒聚集，G3BP1磷酸化阻断应力颗粒组件。不像经典定义的应力颗粒，轴突G3PB1蛋白在未受伤/功能中显示聚集 PNS轴突。这些轴突G3BP1在轴切开术后迅速增加，但降低到低于此后不久，基本水平随磷酸化的G3BP1的相应增加。 G3BP1结合向轴突中的mRNA降低了它们的翻译。我们发现了外源性剂和触发轴突G3BP1聚集体拆卸的内源信号。外源剂明确增加了轴突蛋白合成和体外和IN加速轴突生长速率体内。这些观察结果使我们假设压力的身体聚集轴突中的颗粒蛋白通过阻塞翻译来减弱受伤的PN和CNS的轴突生长轴突mRNA队列。我们将以以下特定目的检验这一假设： AIM 1 - 通过抑制G3BP1功能促进轴突生长。 AIM 2 - 轴突G3BP1聚集拆卸的内源机制。 AIM 3 - 在轴突G3BP1聚集体拆卸后推动轴突生长的机制。轴突翻译的功能作用现已亮起，我们有固体体内证据急性周围神经损伤后，该机制可以靶向加速轴突生长。拟议研究的完成将为临时调节的机制带来新的见解轴突损伤和再生和发现新的治疗策略中的轴突mRNA翻译神经修复。