Hedgehog signaling in lung growth and injury

描述（由申请人提供）：在发育过程中，肺间充质产生非上皮结构，而在成熟肺中，间充质对扰动作出反应以维持稳态。间充质细胞的功能或功能障碍（例如，成纤维细胞、肌成纤维细胞和平滑肌细胞）与许多肺部疾病密切相关，包括肺气肿、哮喘、纤维化、肺动脉高压、癌症和支气管肺发育不良。在我们的知识如何居民间充质细胞功能随着时间的推移在肺部有显着的差距。主要的挑战包括需要额外的标记物来描绘功能上不同的间充质细胞亚型，精确鉴定作为常驻祖细胞或干细胞的间充质细胞，以及鉴定可以治疗靶向的间充质细胞中的新信号传导途径或其他分子。我们工作的广泛目标是鉴定成纤维细胞亚群的新标志物，特别是干/祖细胞，其可用于在疾病状态下鉴定和治疗靶向这些细胞。Sonic hedgehog（Shh）是一种参与肺发育过程中间充质增殖和分化的信号分子。在肺中，Shh由上皮细胞产生，并诱导分支形态发生所需的间充质中的关键反应。虽然Shh的产生在出生时基本上停止，但我们发现在成人肺中仍然存在对Shh或类似的Hedgehog（Hh）配体做出反应的间充质细胞群。这些细胞在Gli 1-lacZ报告小鼠中是可识别的（Gli 1基因既是Hh信号传导途径的组分，也是Hh信号传导的转录靶点）。Hh反应细胞在气道和肺血管的外膜以及脏层胸膜中具有独特的位置。通过共定位研究，我们发现细胞主要是col 1 +SMA-成纤维细胞。基于我们的数据和最近的结果间充质干细胞/祖细胞从其他群体，我们假设Gli 1-lacZ+细胞是一个重要的群体间充质细胞与祖细胞/干细胞的能力。为了验证这一假设，我们提出了两个广泛的目标：（1）在各种条件下对Hh反应细胞进行基因命运图谱，以确定它们在肺中扩增和贡献不同细胞谱系的能力，以及（2）开发分离和培养这些细胞的技术，并表征它们的体外行为。该项目将通过仔细分析各种Hh报告小鼠品系和来自这些小鼠的细胞来完成，并且应该对肺生物学和疾病具有广泛的影响。

DESCRIPTION (provided by applicant): During development, the lung mesenchyme gives rise to non-epithelial structures, while in the mature lung the mesenchyme responds to perturbations to maintain homeostasis. The function, or malfunction, of mesenchymal cells (e.g., fibroblasts, myofibroblasts and smooth muscle cells) is intimately involved with numerous lung diseases, including emphysema, asthma, fibrosis, pulmonary hypertension, cancer and bronchopulmonary dysplasia. There are significant gaps in our knowledge of how resident mesenchymal cells function over time in the lung. Major challenges include the need for additional markers that delineate functionally distinct subtypes of mesenchymal cells, the precise identification of mesenchymal cells that function as resident progenitor or stem cells, and the identification of new signaling pathways or other molecules in mesenchymal cells that can be therapeutically targeted. The broad goal of our work is to identify novel markers of fibroblast subsets, in particular stem/progenitor cells that might be used to identify and therapeutically target these cells in disease states. Sonic hedgehog (Shh) is a signaling molecule involved in mesenchyme proliferation and differentiation during lung development. In lung, Shh is produced by epithelium and induces critical responses in mesenchyme required for branching morphogenesis. While Shh production largely ceases by birth, we find there remains a population of mesenchymal cells in adult lung responding to Shh or a similar Hedgehog (Hh) ligand. These cells are identifiable in Gli1-lacZ reporter mice (the Gli1 gene is both a component of the Hh signaling pathway and a transcriptional target of Hh signaling). The Hh-responding cells have a distinctive location in the adventitia of airways and pulmonary vessels, and in the visceral pleura. By colocalization studies we find that the cells are largely col1+SMA- fibroblasts. Based on our data and recent results on mesenchymal stem/progenitor cells from other groups, we hypothesize that the Gli1-lacZ+ cells are an important population of mesenchymal cells with progenitor/stem cell capability. To test this hypothesis we propose two broad aims: (1) to genetically fate-map the Hh-responding cells under various conditions to determine their ability to expand and contribute to different cell lineages in the lung, and (2) to develop techniques to isolate and culture these cells, and characterize their behavior in vitro. The project will be accomplished by careful analysis of various Hh-reporter mouse strains and cells derived from these mice, and should have broad implications for lung biology and disease.