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) 是导致美国 35 万人和英国 6 万人永久性严重残疾的原因。虽然神经康复方法取得了重要进展，但尚无治疗方法可以显着改善感觉、运动、心血管、泌尿和性功能障碍等许多神经损伤。 SCI 后，由于中枢神经系统 (CNS) 轴突无法再生和重建丢失的回路，功能恢复失败。相反，周围神经系统（PNS）轴突能够部分再生并重新支配其目标，例如在坐骨神经受压后。直接比较支撑这种相反能力的机制可以确定 SCI 后再生的新目标。我实验室最近的研究比较了这种相反的再生能力，发现了一种称为戊糖磷酸途径 (PPP) 的代谢途径，它可以促进 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核苷生物合成所需的 5-磷酸核糖 (R5P) 非常重要。该途径不使用 ATP 形式的能量来生成其产物，因此非常适合损伤后状态，在这种状态下，受损神经元极其需要低能量需求的新代谢物。然而，对于 PPP 在损伤后轴突再生和可塑性中的作用尚不清楚。我实验室的初步实验表明，虽然 PPP 产生的 NADPH 不会影响再生生长，但 DRG 神经突的生长需要依赖于 PPP 的 R5P 和下游核糖核苷的产生。重要的是，我的实验室发现过度表达 PPP 转酮醇酶会强烈增加培养的 DRG 神经元中的神经突生长，并促进体内脊髓损伤后的轴突再生。总而言之，这使我们假设增强 PPP 可以通过增加转录再生反应所需元件的核苷酸的可用性来促进 SCI 后的轴突再生和修复。该提案旨在为 SCI 后 PPP 的再生潜力提供证据，并揭示支撑这种能力的分子机制。最后，它将利用 PPP 依赖性再生反应提出 SCI 后的治疗方案，以临床上合适的具有转化潜力的核苷递送方式促进运动和感觉恢复。具体目标将研究：（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激活与再生基因表达转录联系起来的分子机制； (3) 体内核糖核苷递送作为一种治疗方法，以增加脊髓损伤小鼠模型的可塑性、再生和恢复。该研究项目将通过研究 PPP 依赖性修复机制，提供轴突再生能力代谢控制的另一种观点，从而为损伤的再生反应提供全新的视角，这也将提供新的转化机会。