Regulation of distal lung epithelial regeneration by microRNA-Hippo pathway

 描述（由申请人提供）：气道上皮细胞对损伤的再生能力对于肺从环境损伤中恢复和预防呼吸系统疾病的进展至关重要。因此，重要的是要了解上皮再生是如何调节的，以潜在地促进恢复和减少肺损伤。MicroRNA和Hippo通路已经成为器官发育和成体组织修复和再生的关键调节剂。我们最近证明了microRNA簇miR 302 -367促进了高水平的细胞增殖，但在发育中的肺和心脏中分化程度较低。miR 302 -367在成年心脏中的过表达促进心肌细胞增殖和心脏再生。MiR 302 -367部分通过靶向Hippo信号通路的几个组分发挥作用，Hippo信号通路负调节雅普和Taz的活性。雅普和Taz是关键的转录共激活因子，其驱动其下游靶标的表达以促进细胞增殖并抑制细胞死亡。我们已经探索了细菌性肺炎诱导的成人肺损伤后调节肺泡上皮修复和再生的机制。细菌性肺炎仍然是儿童和老年人死亡的主要原因。虽然广泛的研究集中在细菌毒力和宿主免疫反应，但对细菌性肺炎引起的肺损伤类型及其随后的再生和修复知之甚少。我们发现肺炎链球菌（Sp）感染小鼠肺实质有明显的损伤，随后可见修复和再生。为了响应SP诱导的损伤，肺泡中预先存在的SPC表达上皮II型细胞作为上皮祖细胞发挥功能。它们在受影响的肺泡区域的部位增殖和分化为I型细胞。值得注意的是，miR 302 -367和雅普/Taz靶标、富含半胱氨酸的蛋白61的表达在远端肺上皮中增加。SPC表达细胞中miRNA 302 -367的过表达增强了肺泡上皮的修复和再生。在患有细菌性肺炎的小鼠中施用小分子miR 302模拟物促进远端气道上皮再生，增强小鼠恢复和存活。基于这些初步研究，我们假设miR 302 -367和Hippo通路调节肺上皮基因转录，以促进上皮修复和再生。靶向microRNA-Hippo通路可能代表一种新的治疗方法，以促进细菌性肺炎诱导的损伤的恢复。本项目旨在通过（1）调节小鼠模型系统中肺泡上皮祖细胞中的miR 302 - 367和雅普/Taz表达，以及（2）通过确定miR 302 - 367和Hippo信号传导在控制肺泡上皮修复和再生的调控基因网络中的相互作用，来确定miR 302 -367和Hippo信号传导在远端气道上皮修复和再生中的机制作用，和（3）通过检查miR-模拟物和抑制Hippo通路在从细菌诱导的损伤恢复中的治疗潜力。

 DESCRIPTION (provided by applicant): The regenerative capacity of airway epithelium in response to injury is critical for lung recovery from environmental insults and preventing the progression of respiratory diseases. So it is important to understand how epithelial regeneration is regulated to potentially enhance recovery and reduce lung injury. MicroRNAs and Hippo pathway have emerged as key modulators of both organ development and adult tissue repair and regeneration. We recently demonstrated that the microRNA cluster, miR302-367, promotes a high level of cell proliferation but less differentiated phenotype in the developing lung and heart. Overexpression of miR302-367 in adult heart promotes cardiomyocyte proliferation and cardiac regeneration. MiR302-367 functions, in part, by targeting several components of the Hippo signaling pathway, which negatively regulates the activity of Yap and Taz. Yap and Taz are key transcriptional co-activators that drive the expression of their downstream targets to promote cell proliferation and inhibit cell death. We have explored the mechanisms that regulate alveolar epithelial repair and regeneration in adult lung following injury induced by bacterial pneumonia. Bacterial pneumonia remains a leading cause of mortality in children and the elderly. While extensive studies have focused on bacterial virulence and host immune responses, little is known about the type lung injury induced by bacterial pneumonia and their subsequent regeneration and repair. We show that mice with infection of Streptococcus pneumoniae (Sp) have markedly injuries in the lung parenchyma followed by visible repair and regeneration. In response to Sp-induced injury, pre-existing SPC-expressing epithelial type II cells in the alveolus function as epithelial progenitor cells. They proliferate and differentiate ito type I cell at the sites of affected alveolar region. Notably, the expression of miR302-367 and Yap/Taz target, Cysteine rich protein 61, is increased in distal lung epithelium. Overexpression of miRNA302-367 in SPC- expressing cells enhanced alveolar epithelial repair and regeneration. Administration of small molecule miR302-mimics in mice with bacterial pneumonia promoted distal airway epithelial regeneration, enhanced mouse recovery and survival. Based on these preliminary studies, we hypothesize that miR302-367 and Hippo pathway regulate lung epithelial gene transcription to promote epithelial repair and regeneration. Targeting microRNA-Hippo pathway may represent a novel therapeutic approach to promote recovery from injury induced by bacterial pneumonia. This project aims to define the mechanistic role of miR302-367 and Hippo signaling in distal airway epithelial repair and regeneration by (1) modulating miR302-367 and Yap/Taz expression in alveolar epithelial progenitor cells in murine model system, and (2) by defining the interactions of miR302-367 and Hippo signaling in governing gene network that control alveolar epithelial repair and regeneration, and (3) by examining the therapeutic potentials of miR-mimics and inhibiting Hippo pathway in recovery from bacteria-induced injury.