Snai1/slug-miR30a反馈环路对肾小管上皮细胞间质转化的调控

Epithelial-mesenchymal transformation (EMT) of tubular epithelial cells (TECs) is a fundamental biological process in renal fibrosis. Our previous studies demonstrated that the down-regulation of miR-30a, the high abundance miRNA in TECs, leads to EMT and its target genes are transcriptional repressor snai1 and slug. However, what is the mechanism of miR-30a down-regulation during EMT? Sequence analysis showed that in the promoter region of miR-30a, there are two conserved E-box elements, which are the binding sites of snai1/slug. Our further data showed that these E-box elements mediate the down-regulation of miR-30a and over-expression of snai1/slug could significantly inhibit the expression of miR-30a. Based on these observations, we propose a new mechanism of miR-30a down-regulation: miR-30a and snai1/slug repress the expression of each other in a reciprocal feedback loop to regulate the EMT of TECs during renal fibrosis. This project plans to confirm the expression of miR-30a was directly regulated by snai1/slug, employing the methods of point mutation, EMSA and ChIP. It will elucidate the mechanism on the transcriptional regulation of miR-30a and provide the foundation on snai1/slug or miR-30a as a new target of renal fibrosis therapy.

肾小管上皮细胞间质转化（EMT）是肾脏纤维化的重要生物学过程。我们已证实，肾小管上皮细胞中高丰度的miR-30a表达下调介导EMT，其靶基因为转录抑制因子snai1/slug。那么，miR-30a下调的机制是什么？序列分析表明：miR-30a启动子上具有保守的E-box，即snai1/slug结合位点。进一步实验显示，E-box介导了EMT时miR-30a的下调，且过表达snai1/slug可抑制miR-30a 。由此，我们提出miR-30a下调新机制： snai1/slug转录抑制miR-30a。miR-30a与snai1/slug构成反馈环路，从而加快肾纤维化中的EMT进程。本项目拟采用点突变、EMSA和ChIP等方法，获得snai1/slug直接调控miR-30a的证据，阐明肾小管上皮细胞EMT的新调控机制，为确立snai1/slug或miR-30a作为肾脏纤维化治疗新靶点提供依据。

肾小管上皮细胞间质转化（EMT）是肾脏纤维化的重要生物学过程。我们已证实，肾小管上皮细胞中高丰度的miR-30a表达下调介导EMT，其靶基因为转录抑制因子snai1/slug。本项目旨在厘清miR-30a在肾小管上皮细胞EMT过程中下调的机制。我们采用序列分析、点突变和ChIP等方法，证实snai1可与miR-30a启动子的E-box结合，介导了miR-30a下调。同时我们还发现snai1与miR-30a的表达水平在UUO动物模型，肾纤维化临床标本中呈明显负相关。这表明miR-30a与snai1构成反馈环路，造成肾小管上皮细胞EMT促进肾纤维化。本项目阐明肾小管上皮细胞EMT的新调控机制，为确立snai1/miR-30a通路作为肾脏纤维化治疗新靶点提供了依据。