miR-142-3p靶向调控FoxM1/Nurr1通路在肠缺血再灌注损伤后再生中的作用及机制研究

Damage and repair are two coexistence processes in intestinal ischemia reperfusion (II/R). Deficiency of intestinal mucosal repair mechanism may induce serious complications of II/R. So it has important significance to study the mechanism of intestinal repair and regeneration after II/R injury. In our previous study, we found that Nurr1 promoted the regeneration of intestinal mucosa after II/R injury. Studies have found that FoxM1 promotes the proliferation of stem cells by regulating the expression of Nurr1. We detected the expression of FoxM1 is consistent with Nurr1 in mice model of II/R injury. At the same time, we found that miR-142-3p (miR-142) targeted and negatively correlated with FoxM1. MiR-142 may be involved in regeneration of intestinal mucosa after II/R through regulation of FoxM1/Nurr1 pathway. Therefore, in II/R model of FoxM1-knockout mice and hypoxia/reoxygenation injury model of intestinal epithelial cells, we explore the role of FoxM1/Nurr1 pathway in the repair and regeneration after II/R injury, and the effects of miR-142 targeting FoxM1/Nurr1 signaling pathway in the intestinal regeneration after II/R injury by chromatin immunoprecipitation, luciferase reporter gene and other biological methods.

在肠缺血再灌注(II/R)中损伤和修复是两个并存的过程，肠黏膜损伤后修复机制不足会导致II/R发生严重并发症，研究II/R损伤后肠黏膜修复再生机制具有重要意义。我们之前发现Nurr1促进II/R损伤后肠黏膜的再生，有研究报道FoxM1调控Nurr1促进干细胞增殖。我们在小鼠II/R模型中检测到FoxM1的表达与Nurr1相一致；同时，靶向FoxM1的miR-142-3p (miR-142)与其表达呈负相关，miR-142可能通过靶向调控FoxM1/Nurr1通路参与II/R损伤后肠黏膜的再生。据此，本研究利用FoxM1基因敲除小鼠II/R和肠上皮细胞缺氧复氧模型，采用染色质免疫共沉淀和荧光素酶报告基因等多种分子生物学方法，探讨FoxM1/Nurr1通路在II/R损伤后再生中的作用，研究miR-142靶向FoxM1/Nurr1通路在II/R损伤后再生中的作用及调控机制，并为其治疗提供靶点。

本研究利用大鼠肠缺血再灌注(intestinal ischemia/reperfusion, II/R)模型和IEC-6细胞缺氧复氧(hypoxia/reoxygenation, H/R)模型，采用分子生物学、免疫荧光染色、染色质免疫共沉淀和荧光素酶报告基因等多种分子生物学方法，首次发现：（1）FoxM1的表达与II/R损伤后肠黏膜上皮细胞的增殖明显正相关，FoxM1参与了II/R损伤后肠黏膜上皮细胞的增殖，FoxM1在II/R损伤后修复再生中起促进作用；（2）FoxM1直接结合Nurr1启动子特异性位点促进II/R损伤后修复再生；（3）miR-142-3p (miR-142)在 II/R 损伤后修复再生中起抑制作用；（4）miR-142靶向FoxM1/Nurr1信号通路抑制II/R 损伤后肠黏膜的再生。上述结果证实了我们提出的“miR-142通过靶向调控FoxM1/Nurr1通路参与II/R损伤后肠黏膜的再生”的假说，为II/R损伤的防治提供新的靶点。