miR-21通过TGF-β/Activin信号通路调控脊髓损伤后纤维瘢痕形成及轴突再生的机制研究

Enhancing the intrinsic capacity of the axonal regeneration and reducing the formation of fibrotic scar is the key point for the recovery of nerve function after spinal cord injury(SCI). Studies have shown that the TGF-β/Activin pathway is involved in the regulation of fibroblast fibrosis and axonal regeneration. Our preliminary results showed that miR-21 was significantly increased after SCI, additionally, miR-21 effectively drives nerve regeneration. KEGG pathway indicated miR-21 specifically binding to TGF-β/Activin-related proteins, such as Smad7 and ACVR2B. Based on these findings, we hypothesized: miR-21 regulates the formation of fibrotic scar and axonal regeneration after SCI through TGF-β/Activin pathway by targeting Smad7 and ACVR2B. This proposal aims to elucidate the regulation between miR-21 and TGF-β/Activin pathway, as well as the molecular mechanism involved and the downstream molecules. And demonstrate the role of miR-21 in the formation of fibrotic scar and axonal regeneration after SCI by in vivo studies. Furthermore, we aim to determine the best time point for therapeutic intervention, and provide a alternative for the accurate treatment of SCI.

脊髓损伤（SCI）后提高轴突内生力、减少纤维瘢痕形成是神经功能恢复的关键。研究证实TGF-β/Activin通路对成纤维细胞纤维化及轴突再生有调控作用。申请者前期研究发现miR-21在SCI后表达显著提高，干预miR-21影响神经功能恢复，KEGG pathway分析发现miR-21可靶向结合Smad7、ACVR2B等TGF-β/Activin通路相关蛋白。据此提出：miR-21靶向结合Smad7、ACVR2B调控TGF-β/Activin通路影响SCI后纤维瘢痕形成及轴突再生。课题拟通过细胞实验阐明miR-21调控TGF-β/Activin通路，进而相互作用的分子机制，探寻下游功能靶标，结合体内实验明确SCI后miR-21参与调控轴突内生力、纤维瘢痕形成的作用，探究干预治疗的最佳时间窗口，为SCI的精准治疗提供理论依据。

脊髓损伤（SCI）后提高轴突内生力、减少纤维瘢痕形成是神经功能恢复的关键。研究证实TGF-β/Activin通路对成纤维细胞纤维化及轴突再生有调控作用。申请者前期研究发现miR-21在SCI后表达显著提高，干预miR-21影响神经功能恢复，KEGG pathway分析发现miR-21可靶向结合Smad7、ACVR2B等TGF-β/Activin通路相关蛋白。本课题组利用慢病毒等手段分别在成纤维细胞、星形胶质细胞、神经元细胞中调控miR-21的表达水平，分别观察了脊髓损伤后：1、miR-21在纤维瘢痕的形成中的关键作用，miR-21通过调控SMADs信号通路，减少纤维瘢痕的形成。2、miR-21通过调控星形胶质细胞极化，能够达到抑制胶质瘢痕形成的目的。3、miR-21通过Activin通路，能够显著促进神经元的轴突内生力，加快轴突生长速度。同时在动物实验中，我们构建标准的脊髓损伤模型，并通过antago miR-21干预脊髓损伤局部miR-21的表达水平。通过BMS评分观察小鼠脊髓损伤后恢复情况，通过组织学相关染色观察瘢痕形成及轴突生长的情况，我们发现miR-21能够调控脊髓损伤小鼠损伤区域瘢痕的大小，并显著促进神经元的轴突再生。总之，miR-21在小鼠脊髓损伤后的恢复中起到关键作用，这对于开发新的治疗脊髓损伤的药物具有明确的指导意义。