NGF在坐骨神经再生过程中的动态变化及其调控研究

Peripheral nerve injury is commonly encountered in clinical practice, and peripheral nerve regeneration attracts much research interest. Now, nerve growth factor (NGF) has been widely studied and used in the clinic owing to its important role in nerve regeneration. Since NGF can not easily pass through the blood-nerve barrier, has a short half-life, and may induce undesired side effects when used in a high dosage, it is necessary to apply exogenous NGF at a proper time and in an appropriate dosage based on the dynamic change of endogenous NGF or to develop specific molecules used as therapeutic targets due to their regulatory functions on NGF and their ability to pass easily pass through the blood-nerve barrier. In order to better solve these two issues, therefore, this project is designed to investigate the dynamic change of NGF at the mRNA and protein level during sciatic nerve regeneration, identify miRNAs and transcription factors that regulate NGF at the post-transcriptional and transcriptional level, respectively, search for the upstream regulatory factors of miRNAs and transcription factors, and finally determine the time specificity of NGF-based therapy and the in vivo efficacy of let-7 miRNA according to the expression change of endogenous NGF. This project will be able to add our understanding of the dynamic change and regulation of endogenous NGF during nerve regeneration, provide a theoretical basis for NGF application in peripheral nerve regeneration, and contribute to the development of new therapeutic targets for nerve repair. In addition, our results may probably elucidate the possible pathways through which inflammation enhances nerve regeneration.

周围神经损伤是临床常见病例，神经生长因子（NGF）在神经再生中扮演重要作用，得到了广泛的治疗研究甚至临床应用。但NGF不易通过血神经屏障，半衰期短，而大量用药会引起毒副作用，因此有必要顺应内源NGF的表达变化适时适量地使用外源NGF，或开发易通过血神经屏障的调控NGF的分子作为治疗靶点，而这些方面尚未被深入研究。本项目拟首先确定坐骨神经再生过程中NGF mRNA和蛋白的动态变化；然后寻找对NGF进行转录后调控的miRNA以及转录调控的转录因子，并探讨它们的上游调控因子；最后根据内源NGF的表达变化，对NGF的治疗是否具有时间特异性，靶向调节NGF的let-7 miRNA在体内的应用效果展开研究。本项目旨在揭示内源NGF的变化规律及其调控途径，为更有效地开展NGF的应用研究及优化治疗方案提供理论依据，有助于推动新的治疗靶点的寻找和开发，同时也解读了炎症促神经再生的可能通路。

神经再生微环境中的神经生长因子（NGF）主要被雪旺细胞分泌，外源加入或肌肉注射NGF治疗周围神经损伤得到了广泛的研究甚至临床应用，但NGF不易通过血神经屏障，生物活性半衰期较短，而长期大量用药会引起毒副作用，因此有必要顺应内源NGF的表达变化适时适量的使用外源NGF，或开发易通过血神经屏障的调控NGF的分子作为治疗靶点。本项目首次详细确定内源NGF在坐骨神经损伤与再生过程中的动态变化；也验证了AP-1在施万细胞调控NGF的转录；首次报道和确定let-7 miRNA在转录后水平直接靶向调控神经生长因子NGF，并通过NGF调控施万细胞的增殖、迁移、凋亡和NGF分泌，从而进一步调控轴突生长。因此let-7可以作为调控NGF的分子作为治疗靶点，我们已经在后续研究中开发基于let7的分子组织工程神经。