Nrf2调控FoxO1信号通路改善术后骨骼肌功能的机制研究

For patients undergoing major surgery, the process of postoperative recovery is slow due to the high frequency of morbidity and mortality, which brings heavy burden on patients and the society. In our previous studies, we found that surgery-induced acute muscle wasting was the main cause of low muscle function, which significantly delayed postoperative rehabilitation. Our further experiments demonstrated that the up-regulate of the activity of Nrf2 could reduce nuclear transcriptional activity and expression of FoxO1, reduce postoperative skeletal muscle protein degradation, and enhance the recovery of skeletal muscle function, but the exact mechanism remains unknown. Current studies have proven that FoxO1 is the main pathway causing the degradation of skeletal muscle protein. Therefore, we hypothesis that Nrf2 could inhibit postoperative skeletal muscle protein degradation, improve postoperative skeletal muscle function by regulation of FoxO1 signaling pathway. The present project aims to explore the association between Nrf2 and postoperative skeletal muscle function from the molecular, cellular, organ, and animal levels. Gene transfection and gene knockout technologies, chromatin immunoprecipitation assays, immunofluorescence and skeletal muscle function assessment were used. This project also aims to illustrate the exact regulatory mechanism of Nrf2 on the FoxO1 signaling pathway. Our project is expected to provide experimental evidence for improving postoperative skeletal muscle function and provide new ideas for accelerating postoperative recovery.

经历大手术的患者，术后并发症和死亡率高，术后康复缓慢，给患者和社会带来了沉重负担。我们前期研究发现，术后骨骼肌功能下降会显著延缓术后康复，而手术创伤应激导致的骨骼肌蛋白降解是术后骨骼肌功能下降的主要原因。我们进一步的实验发现，激活Nrf2能减少FoxO1的核转录活性，降低FoxO1的蛋白表达，减少术后骨骼肌蛋白降解，促进骨骼肌功能的恢复，但具体调控机制尚不清楚。有研究证实，FoxO1通路是导致骨骼肌蛋白降解的主要通路。我们推测Nrf2能通过调控FoxO1通路，抑制术后骨骼肌蛋白降解，改善术后骨骼肌功能。本项目拟利用基因转染和基因敲除等技术，采用染色质免疫共沉淀、免疫荧光等实验，通过骨骼肌功能评估，从分子、细胞、器官和动物整体水平探讨Nrf2在改善术后骨骼肌功能中的关键作用，并探究Nrf2对FoxO1通路的具体调控机制。本项目有望为改善术后骨骼肌功能提供实验依据，为加快术后康复提供新的思路。

术后骨骼肌功能下降与不良临床结局密切相关，而手术创伤应激导致的骨骼肌蛋白降解是术后骨骼肌功能下降的主要原因。然而，术后骨骼肌功能下降的确切机制尚不清楚。深入研究术后骨骼肌功能下降的发生机制，寻找有效的防治手段，对于减少术后并发症、加快术后康复、减轻国家医疗负担等具有重要意义。本项目系统地探究了围手术期骨骼肌功能失调的发病机制，为改善骨骼肌功能提供了理论依据。首先，我们通过建立大鼠手术模型，发现术后老年大鼠的骨骼肌细胞存在明显氧化应激损伤，FoxO1和NF-κB表达量显著升高，并从细胞浆内转位至细胞核内，进一步增强了MuRF-l和Atrogin-1基因表达；而激活Nrf2能减少FoxO1的核转录活性，降低FoxO1的蛋白表达，改善骨骼肌纤维萎缩，减轻线粒体损伤。其次，通过建立Nrf2敲除小鼠模型，我们发现，Nrf2基因敲除小鼠较对照组肌纤维横截面积显著降低，骨骼肌线粒体功能出现显著减退且伴有线粒体形态异常。此外，Nrf2基因敲除还进一步加剧增龄导致的线粒体动力学相关蛋白Opa1表达下降。后续研究发现，人参皂苷Rb1可以通过激活Nrf2/ARE信号通路显著抑制术后炎症反应和氧化应激损伤，减轻术后骨骼肌蛋白的降解，并增强其术后活动能力。本研究初步揭示了术后骨骼肌功能失调的分子机制，并发现人参皂苷Rb1能够显著改善骨骼肌功能，为加快术后康复提供了理论基础。