PLASTICITY OF ALVEOLAR EPITHELIAL PHENOTYPIC EXPRESSION

描述(申请人摘要)：该项目的长期目标 应用是为了阐明控制表型表达的机制 肺泡上皮细胞。肺泡上皮由两个部分组成 形态不同的分化上皮细胞，I型和II型 细胞，这两种细胞被认为对正常的肺功能至关重要。 尽管正常肺泡上皮的建立和维持 哺乳动物生命所必需的，控制细胞表达的因素 表型还不是很清楚。在体内，II型细胞有能力 修复受损的肺泡，至少获得I型的一些特征 细胞表型。一种“稳定的”细胞表型改变的过程 转化为另一种表型被称为“转分化”。来自体外 对II型细胞的研究，已经提出了转分化 从II型到I型的细胞表型是可逆的。加在一起， 体内和体外的观察产生了以下假设： 1)转分化可以在II型和I型之间双向发生 2)各表型的表达存在反向共调控。缺欠 合适的细胞培养模式和足够数量的细胞特异性 生物化学和分子标记使研究其调控变得困难。 在肺中的表型表达。尽管在这方面已经取得了进展 开发合适的标记和体外系统，仍然只有一种 少量的细胞特异性标志物。另一个重大问题是 缺乏分离和培养I型细胞的方法学。我们最近做了 开发了分离、培养和转染I型细胞的方法， 允许在体外对这种细胞类型进行直接研究。在本申请中， 我们建议研究比较新分离的(I型和II型)细胞和 在有利于表达某一种基因的条件下培养的细胞 表型以实现四个目标：1)定义功能和分子 更详细的每种表型的特征；2)识别其他 每种表型的特定标记；3)确定 在体外发生转分化；4)鉴定和测试候选 调节转分化的基因。这类研究的结果是 对临床问题的潜在应用。因为急性发作后的恢复 肺损伤依赖于正常肺泡上皮的再生。 对肺泡上皮细胞表型表达的更多了解 监管可能导致新的可检验假设的发展 急性肺损伤的治疗。

DESCRIPTION (Applicant's Abstract): The long-term objectives of this application are to elucidate the mechanisms that control phenotypic expression of the alveolar epithelium. The alveolar epithelium comprises two morphologically distinct differentiated epithelial cells, type I and type II cells, both of which are thought to be critical for normal lung function. Although the establishment and maintenance of normal alveolar epithelium is essential for mammalian life, factors controlling the expression of cellular phenotype are not well understood. In vivo, type II cells have the capacity to repair injured alveoli, acquiring at least some characteristics of the type I cell phenotype. The process by which one "stable" cellular phenotype changes into another phenotype has been termed "transdifferentiation." From in vitro studies with type II cells, it has been proposed that the transdifferentiation from the type II to the type I cell phenotype is reversible. Taken together, the observations in vivo and vitro have generated the following hypotheses: 1)transdifferentiation can occur bi-directionally between type II and type I cells; 2)there is inverse co-regulation of expression of each phenotype. Lack of suitable cell-culture models and sufficient numbers of cell-specific biochemical and molecular markers has made it difficult to study regulation of phenotypic expression in the lung. Although progress has been made in the development of appropriate markers and in vitro systems, there are still only a small number of cell-specific markers. Another significant problem has been the lack of methodology for isolating and culturing type I cells. We have recently developed methods for isolating, culturing, and transfecting type I cells, permitting direct study of this cell type in vitro. In the current application, we propose studies comparing freshly isolated (type I and type II) cells to cells cultured under conditions that favor expression of one or the other phenotype to achieve four goals: 1) to define functional and molecular characteristics of each phenotype in greater detail; 2) to identify additional specific markers for each phenotype; 3) to determine the extent to which transdifferentiation occurs in vitro; 4) and to identify and test candidate genes for regulating transdifferentiation. The results of such studies have potential applications to clinical problems. Because the recovery from acute lung injury is dependent on the regeneration of a normal alveolar epithelium, a greater understanding of how alveolar epithelial phenotypic expression is regulated may lead to the development of new testable hypotheses regarding treatments for acute lung injury.