PLASTICITY OF ALVEOLAR EPITHELIAL PHENOTYPIC EXPRESSION

描述（申请人的摘要）：本发明的长期目标是： 应用是为了阐明控制表型表达的机制 肺泡上皮细胞。肺泡上皮细胞由两个 形态上不同的分化上皮细胞，I型和II型 这两种细胞都被认为对正常的肺功能至关重要。 虽然正常肺泡上皮的建立和维持是 哺乳动物生命所必需的，控制细胞表达的因子， 表型还不清楚。在体内，II型细胞有能力 修复受损的肺泡，获得至少一些I型特征 细胞表型一个“稳定”细胞表型改变的过程 转化为另一种表型的过程被称为“转分化”。“从体外 在II型细胞的研究中，已经提出转分化 从II型到I型细胞表型的转变是可逆的。综合起来看， 体内和体外观察结果产生了以下假设： 1)转分化可以在II型和I型之间双向发生 细胞; 2）存在每种表型的表达的反向共调节。缺乏 合适的细胞培养模型和足够数量的细胞特异性 生物化学和分子标记使得研究 在肺中的表型表达。虽然在这方面取得了进展， 尽管开发了适当的标记物和体外系统， 少量的细胞特异性标志物。另一个重要的问题是， 缺乏分离和培养I型细胞的方法。我们最近 开发了用于分离、培养和分离I型细胞的方法， 允许在体外直接研究这种细胞类型。在当前应用中， 我们提出了比较新鲜分离的（I型和II型）细胞与 在有利于一种或另一种表达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 更详细地描述每种表型的特征; 2）识别额外的 每种表型的特异性标记; 3）确定 转分化发生在体外; 4）并鉴定和测试候选物 调节转分化的基因。这些研究的结果 潜在的临床应用问题。因为从急性 肺损伤依赖于正常肺泡上皮细胞的再生， 更好地理解肺泡上皮细胞表型表达是如何 监管可能会导致新的可检验的假设的发展， 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.