Investigating coupling of metabolism with gene transcription to support the axonal regeneration programme for repair

研究代谢与基因转录的耦合以支持轴突再生程序的修复

• 批准号: MR/X003663/1
• 负责人: Simone Di Giovanni
• 金额: $ 104.36万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FX003663%2F1
• 关键词: Investigating; coupling; metabolism; gene; transcription

Spinal cord injury (SCI) is a cause of permanent severe disability in 350,000 people in the US and 60,000 in the UK alone. While neurorehabilitation approaches have made important advances, no treatment is available to significantly improve the many neurological impairments spanning from sensory, motor, cardiovascular, urinary and sexual dysfunction. Following SCI, functional recovery fails due to the inability of central nervous system (CNS) axons to regenerate and re-establish lost circuits. Conversely, peripheral nervous system (PNS) axons are able to partially regenerate and reinnervate their targets such as after a compression of the sciatic nerve for example. A direct comparison of the mechanisms underpinning this opposite ability can lead to identify new targets for regeneration after SCI. Recent studies in my laboratory comparing this opposite regenerative ability led to the discovery of a metabolic pathway called Pentose Phosphate Pathway (PPP) that promotes regeneration and repair after SCI. The PPP uses sugar (glucose) to produce NADPH that is important to reduce free radicals and ribose-5-phosphate (R5P), needed for nucleoside biosynthesis. This pathway does not use energy in the form of ATP to generate its products and it is therefore ideally suited in a post-injury state where damaged neurons have an extreme need for new metabolites with a low energy demand. However, nothing is known about the role of the PPP in axonal regeneration and plasticity after injury. Initial experiments in my lab showed that while PPP production of NADPH does not affect regenerative growth, PPP-dependent R5P and downstream ribonucleoside production are needed for DRG neurite outgrowth. Importantly, my lab found that overexpressing the PPP enzyme transketolase strongly increases neurite outgrowth in cultured DRG neurons and it promotes axonal regeneration after a spinal cord injury in vivo. Altogether, this led us to hypothesise that boosting the PPP could promote axonal regeneration and repair after SCI by increasing the availability of nucleotides that are the elements needed for a transcriptional regenerative response. This proposal aims to provide evidence for the regenerative potential of the PPP after SCI and to unravel the molecular mechanisms underpinning this ability. Lastly, it will leverage upon the PPP-dependent regenerative response to propose treatment after SCI in order to promote locomotor and sensory recovery in a clinically suitable delivery modality of nucleosides with translational potential. The specific aims will investigate: (1) the ability of transketolase overexpression to promote regeneration and synaptic plasticity after SCI; (2) the molecular mechanisms linking PPP activation with transcription for regenerative gene expression; (3) in vivo ribonucleosides delivery as a treatment to increase plasticity, regeneration and recovery post-SCI in mouse models of spinal cord injuries. This research project will shed a completely new light on the regenerative response to injury by providing an alternative view of the metabolic control of the axonal regenerative ability by investigating PPP-dependent repair mechanisms that will also offer novel translational opportunities.

脊髓损伤（SCI）是美国350,000人永久性严重残疾的原因，仅英国就有60,000人。尽管神经康复方法已取得了重要进展，但没有治疗可显着改善从感觉，运动，心血管，尿液和性功能障碍的许多神经系统障碍。在SCI之后，由于中枢神经系统（CNS）轴突无法再生和重新建造损耗的电路，功能恢复失败。相反，外周神经系统（PNS）轴突能够部分再生并重新弥补其靶标，例如在压缩坐骨神经之后。对这种相反能力的机制的直接比较可以导致识别SCI后再生目标的新目标。在我的实验室中，比较了相反的再生能力的最新研究导致发现了一种称为五肽磷酸五磷酸戊糖途径（PPP）的代谢途径，该途径促进了SCI后的再生和修复。 PPP使用糖（葡萄糖）产生NADPH，这对于减少自由基和5-磷酸核糖（R5P）很重要，这是核苷生物合成所需的。该途径不以ATP的形式使用能量来生成其产品，因此，它非常适合在伤害后状态下，在伤害后的神经元中，受损的神经元非常需要低能量需求的新代谢产物。然而，对PPP在受伤后的轴突再生和可塑性中的作用一无所知。我实验室中的初始实验表明，虽然NADPH的PPP产生不影响再生生长，但依赖PPP的R5P和下游核糖核苷的产生需要DRG神经突生长。重要的是，我的实验室发现，过表达PPP酶的转酮酶强烈增加了培养的DRG神经元中的神经突生长，并且在体内脊髓损伤后促进轴突再生。总之，这使我们假设通过增加核苷酸的可用性，这是转录再生反应所需的元素，可以提高PPP的促进SCI后轴突再生和修复。该提案旨在为SCI后PPP的再生潜力提供证据，并揭示该能力支撑的分子机制。最后，它将利用对SCI后提出的PPP依赖性再生反应，以促进具有转化潜力的核苷的临床适当递送方式中的运动和感觉恢复。具体目的将研究：（1）转酮醇酶过表达促进SCI后再生和突触可塑性的能力； （2）将PPP激活与转录的分子机制与再生基因表达相关； （3）在脊髓损伤的小鼠模型中，体内核糖核苷作为一种治疗方法，以增加可塑性，再生和恢复后。该研究项目将通过研究依赖PPP依赖性修复机制的轴突再生能力的代谢控制的替代观点，从而为对伤害的再生反应提供全新的启示，这些观点也将提供新的翻译机会。