Post-Transcriptional Regulation of Lung Fibrosis.

项目总结/摘要 特发性肺纤维化（IPF）是一种致死性进行性纤维化疾病，其特征在于过度沉积的 细胞外基质（ECM）蛋白。持续的肌成纤维细胞活化被认为是驱动力之一 导致IPF中ECM蛋白过度产生和纤维化。使人类得以延续的分子机制 IPF中持续的肌成纤维细胞活化和促纤维化反应尚未完全了解。KH型 剪接调节蛋白（KSRP）是一种mRNA去稳定蛋白，参与转录后调控， 基因表达。初步数据表明，KSRP表达在IPF肺中显著降低， 与正常人肺成纤维细胞和组织相比，然而，作用 KSRP在肺纤维化中的作用，以及在促纤维化中病理性KSRP下调的功能后果。 IPF的缓解情况完全未知。该建议旨在揭示KSRP在以下方面的新限制作用： 肺纤维化及其分子机制。初步数据表明，KSRP缺陷小鼠 与野生型小鼠相比，对博莱霉素的反应增加了肺纤维化， KSRP缺乏促进肌成纤维细胞分化和ECM蛋白产生，而KSRP获得抑制肌成纤维细胞分化和ECM蛋白产生。 这些数据表明，KSRP作为纤维化反应的限制因素发挥作用， 促进纤维化反应和肺纤维化。此外，KSRP负调节Migfilin mRNA的稳定性 表达和KSRP缺陷导致Migfilin表达增加。我们的初步数据显示 Migfilin作为“促纤维化开关”发挥作用，促进促纤维化反应。以下情况需要Migfilin 肌成纤维细胞分化和存活。根据初步数据，我们假设KSRP的功能是 肺纤维化的限制性调节因子，并且受损的KSRP功能促进了“促纤维化生态位”， 持续的肌成纤维细胞分化和促纤维化反应介导的Migfilin和Migfilin介导的 发信号。为了检验这一假设，提出了三个具体的目标。特定的AIM 1将决定 KSRP调节肌成纤维细胞分化和存活的机制。特定的AIM 2将决定 KSRP在控制ECM表达和基质组装中的限制性作用。具体目标3将检查 KSRP在纤维发生和功能后果中体内细胞特异性作用。这些发现将有助于 了解IPF中持续存在肌成纤维细胞活化和促纤维化反应的机制 并服务于我的长期目标，即开发有效的IPF治疗方法。

PROJECT SUMMARY/ABSTRACT Idiopathic pulmonary fibrosis (IPF) is a fatal progressive fibrotic disease characterized with excessively deposited extracellular matrix (ECM) proteins. Persistent myofibroblast activation is considered as one of driving forces that lead to excessive ECM protein production and fibrosis in IPF. The molecular mechanisms that perpetuate persistent myofibroblast activation and pro-fibrotic responses in IPF have not been fully understood. KH-Type Splicing Regulatory Protein (KSRP) is a mRNA destabilizing protein involved in post-transcriptional regulation of gene expression. Preliminary data demonstrate that KSRP expression is significantly decreased in IPF lung fibroblasts and tissues when compared to that in normal human lung fibroblasts and tissues. However, the role of KSRP in lung fibrosis, and the functional consequences of pathologic KSRP downregulation in pro-fibrotic responses in IPF, are completely unknown. This proposal aims to reveal the novel restrictive role of KSRP in lung fibrosis and the molecular mechanisms involved. Preliminary data demonstrate that KSRP deficient mice have increased lung fibrosis when compared to wild-type mice in response to Bleomycin, and that KSRP deficiency promotes, while gain of KSRP inhibits, myofibroblast differentiation and ECM protein production. These data indicate that KSRP functions as a restricting factor of fibrotic reactions, and impaired KSRP function promotes fibrotic reactions and lung fibrosis. Furthermore, KSRP negatively regulates Migfilin mRNA stability and expression and KSRP deficiency results in increased Migfilin expression. Our preliminary data demonstrate that Migfilin functions as a “pro-fibrotic switch”, promoting pro-fibrotic reactions. Migfilin is required for myofibroblast differentiation and survival. Based on preliminary data, we hypothesize that KSRP functions as a restrictive regulator of lung fibrosis, and that impaired KSRP function fosters a “pro-fibrotic niche” fueling persistent myofibroblast differentiation and pro-fibrotic responses mediated by Migfilin and Migfilin mediated signaling. To test the hypothesis, three specific AIMs are proposed. Specific AIM 1 will determine the mechanisms by which KSRP regulates myofibroblast differentiation and survival. Specific AIM 2 will determine the restrictive role of KSRP in controlling ECM expression and matrix assembly. Specific AIM 3 will examine the in vivo cell-specific role of KSRP in fibrogenesis and functional consequences. The findings will help to understand the mechanisms that perpetuate persistent myofibroblast activation and pro-fibrotic responses in IPF and serve my long-term goal to develop effective therapy for IPF.