黄芩素下调miR-21表达抑制肺成纤维细胞转化的分子机制研究

Lung fibroblasts play a very important role in the development of pulmonary fibrosis. Our previous studies have showed that baicalein inhibits abnormal transition of lung fibroblasts and significantly reduces the level of miR-21 in cell and animal model of pulmonary fibrosis. Based on the literature and our previous findings, we reasoned that miR-21 might be an important regulatory factor in the effect of baicalein-suppressed abnormal transition of lung fibroblasts. To test this hypothesis, on the basis of previous work, transforming growth factor beta 1-induced abnormal human lung fibroblast transition cell model is used to study the following three aspects, (1) to investigate the role of miR-21 in the inhibitory effect of baicalein on abnormal transition of lung fibroblasts; (2) to determine the effect of baicalein on the upstream regulation factors of miR-21; (3) to identify the miR-21 downstream proteins associated with abnormal transition of lung fibroblasts and to elucidate the roles of those miR-21 downstream proteins in the effect of the inhibitory effect of baicalein on abnormal transition of lung fibroblasts. The completion of this project will deepen the understanding of the mechanism of baicalein, and provide a novel perspective for research and applications of baicalein and other anti-fibrotic drugs. Moreover, it will enrich the contents about the relationship between miR-21 signaling pathway and lung fibroblast transition.

肺成纤维细胞在肺纤维化疾病发展过程中扮演着非常重要的角色。申请人前期在肺纤维化疾病细胞模型和动物模型上发现，黄芩素可抑制肺成纤维细胞转化，并可显著下调miR-21表达。结合文献，申请人推测miR-21是黄芩素发挥抑制肺成纤维细胞转化作用的一个重要调控因子。为证实这一假说，本项目将在前期工作的基础上，拟采用转化生长因子β1诱导人肺成纤维细胞转化模型开展以下三方面的研究：①探讨黄芩素抑制肺成纤维细胞转化作用与miR-21表达变化的关系；②探讨黄芩素通过调控miR-21上游转录因子来下调miR-21表达的分子机制；③鉴定参与肺成纤维细胞转化过程的miR-21下游靶蛋白，并探讨这些靶蛋白在黄芩素抑制肺成纤维细胞转化过程中的作用。本项目的完成将加深对黄芩素抗肺纤维化作用机制的认识，为黄芩素和其它抗肺纤维化药物的研究和应用提供新视角，同时也将丰富miR-21信号通路与肺成纤维细胞转化关系的内涵。

靶向肺成纤维细胞转化是目前肺纤维化疾病治疗的重要靶点。我们采用转化生长因子β1诱导人肺成纤维细胞转化模型开展了以下四方面的研究：①发现了黄芩素能够明显抑制肺成纤维细胞转化，且该作用与黄芩素下调miR-21表达水平有关；②发现了黄芩素可抑制miR-21上游转录因子STAT3的活化，但不影响miR-21另一重要上游转录因子AP1的激活；③发现了参与肺成纤维细胞转化过程的miR-21下游靶蛋白Spry1、Smuf2两个新分子，并证实Spry1参与了黄芩素抑制肺成纤维细胞转化的作用，而Smuf2未参与该作用；④发现了黄芩素可显著抑制细胞外基质I型胶原蛋白产生，该作用与黄芩素抑制CTGF通路有关。上述研究结果既为黄芩素治疗肺纤维化疾病提供了理论依据，又丰富了miR-21信号通路与肺成纤维细胞转化关系的内涵，更为从黄芩素保护肺泡上皮细胞损伤的新角度深入探讨黄芩素减轻肺纤维化的作用及其分子机制提供了可靠保证。