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：
10030563
负责人：
JEFFERY L TWISS
金额：
$ 57.54万
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/10030563
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 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 regenerative 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，但轴突生长速度极其缓慢，因此人类的轴突再生很少实现目标的完全功能性再神经支配。中枢神经系统更糟，例如患有脊髓损伤（SCI）的人几乎总是在病变水平以下永久丧失感觉和运动功能。迫切需要加速周围神经系统的轴突再生增加中枢神经系统的轴突再生。轴突内合成的蛋白质支持轴突生长的内在机制。我们已经证明 PNS 神经元保留了合成蛋白质的能力。它们的轴突和这些蛋白质支持培养的神经元轴突的生长。数以千计的 mRNA——以及多条证据表明中枢神经系统中存在复杂的 mRNA 群体当鼓励时，体内轴突和脊髓轴突含有 mRNA 和翻译机制尽管有允许的基质再生。自 2000 年代初期以来，决定何时何地的分子机制取得了显着进展轴突中翻译的特定 mRNA 在很大程度上仍不清楚。对于调节轴突生长能力至关重要我们已经证明 mRNA 储存在 PNS 轴突中。含有应激颗粒蛋白 G3BP1 的 RNA 蛋白聚集体可以驱动 G3BP1 蛋白。与应激颗粒聚集不同，G3BP1 磷酸化会阻止应激颗粒组装。经典定义的应激颗粒，轴突 G3PB1 蛋白显示未受伤/功能状态下的聚集这些轴突 G3BP1 聚集体在轴突切除后迅速增加，但减少到以下。此后不久，G3BP1 的磷酸化水平相应增加。我们发现了外源性因子和作用。触发轴突 G3BP1 聚集体分解的内源信号。在体外和体内特异性地增加轴突蛋白质合成并加速轴突生长速率这些观察结果引导我们与压力的生理聚集作斗争。轴突中的颗粒蛋白通过阻断翻译来减弱受伤的三七和中枢神经系统的轴突生长我们将通过以下具体目标来检验这一假设：目标 1 – 通过抑制 G3BP1 功能促进轴突生长。目标 2 – 轴突 G3BP1 聚集体分解的内源机制。目标 3 – 轴突 G3BP1 聚集体分解后驱动轴突生长的机制。轴突翻译的功能作用现已揭示，我们有可靠的体内证据该机制可以有针对性地加速急性周围神经损伤后的轴突生长。完成拟议的研究将为时间调节机制带来新的见解轴突损伤和再生中轴突 mRNA 翻译的研究，并揭示新的治疗策略神经修复。