LUNG ALVEOLAR TYPE 1 CELL MORPHOGENESIS

肺泡 1 型细胞形态发生

• 批准号: 7145832
• 负责人: Maria Isabel Ramirez
• 金额: $ 40.63万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7145832
• 关键词: Caenorhabditis elegans; Drosophilidae; cell differentiation; cell morphology; developmental genetics; flow cytometry; gene expression profiling; green fluorescent proteins; laboratory mouse; lung development; respiratory epithelium; small interfering RNA; tissue /cell culture; transcription factor; transfection

DESCRIPTION (provided by applicant): The objective of this proposal is to define the molecular mechanisms of lung alveolar type I cell development, focusing on one of the principal features of type I cells, their extensive, thin, flat shape. In late gestation, precursor distal lung epithelial cells change their shape from cuboidal to flat, acquiring the structural and molecular features of differentiated type I cells to form the thin alveolar gas exchange surface. We hypothesize that genes that regulate plasma membrane growth and polarization, and cytoskeletal organization play a critical inductive and/or permissive role in the process of late fetal type I cell development. We will analyze three important features of alveolar type I cells: shape, type I specific gene expression, and flattening-related gene expression. We will selectively modify each of these features and study alterations in the other two. This approach will provide important information about the molecular mechanisms that initiate and/or sustain type I cell morphogenesis. We will study in the developing lung the roles of genes associated with epithelial cell expansion and flattening identified in Drosophila and C. elegans, and of genes associated with altered cell shape in T1a null mutant mouse, where type I cell formation is impaired. We will determine when and where these genes are expressed in normal lung. We will evaluate their role in cell flattening and spreading using type l-precursor cells isolated at different developmental stages from fetal lungs expressing GFP driven by the promoter of the type I cell gene T1a. We will increase or reduce expression of selected genes in vitro to determine effects on epithelial cell flattening and spreading and on type I specific gene expression. We will modulate the shape of epithelial cells in vitro using culture conditions that restrict spreading and evaluate type I specific and cell-flattening-related gene expression. Finally, we will evaluate the role of these genes in vivo using developing lungs with impaired type I cell differentiation. Analysis of type I cells by these approaches will provide new insights into the regulation of type I cell formation in the fetal lung. This regulation is likely important for type I cell morphogenesis in postnatal lung growth and in lung repair after injury in the adult lung. Relevance to Public Health: When lung development is delayed or babies are delivered prematurely the cells that line the lung alveoli are immature and cannot efficiently perform the normal process of gas exchange. Identifying the key genes that control alveolar cell formation is important to allow the design of new treatments to stimulate newborn lung maturation. Similar mechanisms could apply to the process of alveolar cell healing after injuries caused by infections or environmental factors. Therefore these studies will provide new understanding of the regulation of type I formation that likely will improve treatment of acute and chronic lung diseases in the adult.

描述（由申请人提供）：本提案的目的是定义肺泡 I 型细胞发育的分子机制，重点关注 I 型细胞的主要特征之一，即其广泛、薄而扁平的形状。在妊娠晚期，前体远端肺上皮细胞的形状从立方体变为扁平体，获得分化的 I 型细胞的结构和分子特征，形成薄的肺泡气体交换表面。我们假设调节质膜生长和极化以及细胞骨架组织的基因在晚期胎儿 I 型细胞发育过程中发挥关键的诱导和/或许可作用。我们将分析肺泡 I 型细胞的三个重要特征：形状、I 型特异性基因表达和扁平化相关基因表达。我们将有选择地修改其中的每一个功能，并研究其他两个功能的更改。这种方法将提供有关启动和/或维持 I 型细胞形态发生的分子机制的重要信息。我们将研究在发育中的肺中与果蝇和线虫中发现的上皮细胞扩张和扁平相关的基因的作用，以及与 T1a 无效突变小鼠中细胞形状改变相关的基因的作用，其中 I 型细胞形成受损。我们将确定这些基因在正常肺部表达的时间和地点。我们将使用从表达由 I 型细胞基因 T1a 启动子驱动的 GFP 的胎肺中分离出的不同发育阶段的 I 型前体细胞来评估它们在细胞扁平化和扩散中的作用。我们将在体外增加或减少选定基因的表达，以确定对上皮细胞扁平化和扩散以及对 I 型特异性基因表达的影响。我们将使用限制扩散的培养条件在体外调节上皮细胞的形状，并评估 I 型特异性和细胞扁平化相关的基因表达。最后，我们将利用 I 型细胞分化受损的发育中肺来评估这些基因在体内的作用。通过这些方法对 I 型细胞的分析将为胎儿肺中 I 型细胞形成的调节提供新的见解。这种调节可能对于出生后肺生长和成人肺损伤后的肺修复中的 I 型细胞形态发生很重要。与公共健康的相关性：当肺部发育延迟或婴儿过早分娩时，肺泡内的细胞不成熟，无法有效地执行正常的气体交换过程。识别控制肺泡细胞形成的关键基因对于设计刺激新生儿肺成熟的新疗法非常重要。类似的机制可能适用于感染或环境因素造成的损伤后肺泡细胞的愈合过程。因此，这些研究将为 I 型形成的调节提供新的认识，这可能会改善成人急性和慢性肺部疾病的治疗。