miR-31 as a Negafive Regulator of Pulmonary Fibrosis

项目总结(见说明)： 特发性肺纤维化(IPF)是最有害的肺纤维化类型之一，目前尚无明显有效的治疗方法。虽然IPF的病因仍是个谜，但有大量证据表明，IPF肺成纤维细胞的纤维生成、分化、收缩和迁移功能失调。然而，miRNAs在IPF成纤维细胞(IPF-FBS)中调节这种异常活性的作用尚不清楚。在我们的初步研究中，我们发现在博莱霉素诱导的肺纤维化小鼠的肺组织中miR-31的表达下调。靶点预测表明miR-31调节整合素α和RhoA的表达。这些蛋白是肺成纤维细胞纤维化形成、分化、收缩和迁移的关键调节因子。这一信息与我们的初步数据一起表明，miR-31可能在IPF的发生和发展中发挥重要作用。因此，miR-31似乎是开发治疗IPF的新疗法的潜在靶点。我们的初步数据显示，miR-31模拟物的引入可以减轻博莱霉素诱导的肺纤维化的严重程度，这有力地支持了这一假说。在本建议中，我们的目标是：确定miR-31在IPF-FBS中下调的转录和表观遗传学机制；确定miR-31是否针对RhoA和整合素α，从而调节IPF-FBS的收缩、迁移和纤维化活性；确定通过气管内或胸膜内给药重建肺组织miR-31是否在治疗小鼠肺纤维化模型中显示出治疗潜力；确定miR-31是否能抑制PMC-肌成纤维细胞的分化/激活；miR-31的表达是否受到Src激酶信号通路的调节；以及miR-31的抗纤维化活性是否由IPF-FBS中的N0X4介导。

PROJECT SUMMARY (See instructions): Idiopathic pulmonary fibrosis (IPF) is one ofthe most pernicious forms of lung fibrogenesis and currently has no clearly effective treatments. Whereas the etiology of IPF remains enigmatic, there is a plenty of evidence showing dysregulated fibrogenesis, differentiation, contractility and migration of pulmonary fibroblasts from IPF lungs. However, the role of miRNAs in regulation of such aberrant activities in IPF fibroblasts (IPF-Fbs)is unknown. In our preliminary studies, we found that the expression of miR-31 is downregulated in the lungs of mice with bleomycin induced lung fibrosis. Target predictions demonstrate that miR-31 regulates the expression of integrin alphas and RhoA. These proteins are critical regulators of fibrogenesis, differentiation, contractility and migration of pulmonary myofibroblasts. This information, together with our preliminary data, suggests that miR-31 may play an important role in initiation and progression of IPF. Therefore, miR-31 appears to be a potential target for developing novel therapeutics to treat IPF. Our preliminary data showing that introduction of miR-31 mimics diminishes the severity of bleomycin induced lung fibrosis lend a strong support to this hypothesis. In this proposal, we aim to; determine the transcriptional and epigenetic mechanisms by which miR-31 is downregulated in IPF-Fbs; determine if miR-31 targets RhoA and integrin alphas, and thereby regulating the contractile, migratory, and fibrogenic activities of IPF-Fbs; determine if reconstitution of pulmonary miR-31 through intra-tracheal or intra-pleural delivery demonstrates therapeutic potentials in treating lung fibrosis in mouse models; determine if miR-31 inhibits PMC-myofibroblast differentiation/activation, if miR-31 expression is regulated by Src kinase signaling pathways, and if the antifibrogenic activity of miR-31 is mediated by N0X4 in IPF-Fbs.