The Role of KCNMB1 and the Large Conductance Potassium (BK) Channel in Myofibroblast Differentiation and Pulmonary Fibrosis

项目摘要 尽管对肺纤维化发病机制的理解取得了重大进展，但许多治疗方法仍然存在局限性。 靶向研究最充分的基因和途径的药物在逆转或 甚至阻止疾病的发展这沿着特发性骨髓瘤患者的临床异质性， 肺纤维化（IPF），表明在疾病发病机制模型中考虑其他基因可能是 有用的.与正常人相比，IPF患者的成纤维细胞在许多基因表达方面存在差异 成纤维细胞，这个实验室长期以来一直有兴趣确定表观遗传变化， 对于这些差异。KCNMB 1编码大电导的β亚基（BK，Maxi-K，KCa1.1） 钾通道，并在我们以前的微阵列研究中被确定为最高的差异甲基化基因 在IPF成纤维细胞中。BK通道调节钾电流，并且众所周知在血管内皮细胞中是重要的。 张力和平滑肌生物学，但其在纤维化中的重要性从未被研究过。我们最近展示了 在一篇出版物中，1）KCNMB 1在IPF患者成纤维细胞中表达增加，2）KCNMB 1 有助于增加BK通道活性，和3）BK通道功能的增加促进肌成纤维细胞 分化，IPF的标志。如何做到这一点，以及这是否足以促进或恶化肺 体内纤维化是未知的。这项资助的目的是确定BK通道如何 有助于肌成纤维细胞的分化，并建立BK通道的动物模型的重要性， 肺纤维化我们的中心假设是，KCNMB 1的表观遗传上调和BK的增加， IPF成纤维细胞中的通道活性通过促进成纤维细胞中的钙信号传导而促成肺纤维化， 导致肌成纤维细胞分化。第一个目标是建立BK渠道的重要性 在体内肺纤维化的发展，并定位其致病作用的肺成纤维细胞。第二 目的是描述BK通道促进肌成纤维细胞分化的机制， 假设BK通道促进细胞内钙信号传导，这是分化为 肌成纤维细胞第三个目的是确定KCNMB 1在肺成纤维细胞中的表达是如何调节的， 促纤维化刺激如何调节BK通道的开放和关闭。这一建议意义重大，因为它 建立BK通道作为一种新的，但在肺纤维化的发病机制的重要驱动程序。 实现这些目标还将确定BK通道在分化中的机制和作用。 肌成纤维细胞，以前从未描述过。最终，这些研究将有助于确定新的 未来IPF治疗的目标。

PROJECT SUMMARY Despite major advances in the understanding of the pathogenesis of pulmonary fibrosis, many of the therapies that target the most well-studied genes and pathways have not achieved universal success in reversing or even halting disease progression. This, along with the clinical heterogeneity of patients with idiopathic pulmonary fibrosis (IPF), suggest that consideration of other genes in models of disease pathogenesis may be useful. Fibroblasts from patients with IPF differ in the expression of many genes compared to normal fibroblasts, and this laboratory has had a longstanding interest in identifying epigenetic changes that account for these differences. KCNMB1 codes for the beta subunit of the large conductance (BK, Maxi-K, KCa1.1) potassium channel and was identified in our previous microarray study as the top differentially methylated gene in IPF fibroblasts. BK channels modulate potassium current and are well known to be important in vascular tone and smooth muscle biology, but its importance in fibrosis has never been examined. We recently showed in a publication that 1) KCNMB1 expression is increased in fibroblasts from IPF patients, 2) KCNMB1 contributes to increased BK channel activity, and 3) increased function of BK channels promote myofibroblast differentiation, a hallmark of IPF. How it does so and whether this is sufficient to promote or worsen pulmonary fibrosis in vivo is unknown. The objectives of this grant are to determine the mechanism of how BK channels contribute to myofibroblast differentiation and establish the importance of BK channels to animal models of pulmonary fibrosis. Our central hypothesis is that the epigenetic upregulation of KCNMB1 and increased BK channel activity in IPF fibroblasts contribute to pulmonary fibrosis by promoting calcium signaling in fibroblasts, which lead to myofibroblast differentiation. The First Aim is to establish the importance of BK channels to the development of pulmonary fibrosis in vivo, and localize its pathogenic actions to lung fibroblasts. The Second Aim is to delineate the mechanism by which BK channels contribute to myofibroblast differentiation, with the hypothesis that BK channels promote intracellular calcium signaling, which is necessary for differentiation into myofibroblasts. The Third Aim is to determine how expression of KCNMB1 is regulated in lung fibroblasts and how profibrotic stimuli modulates opening and closing of BK channels. This proposal is significant because it establishes BK channels as a novel, but important driver in the pathogenesis of pulmonary fibrosis. Accomplishing these aims will also identify a mechanism and role for BK channels in the differentiation of myofibroblasts that has never been previously described. Ultimately, these studies will serve to identify new targets for future IPF therapeutics.