REGULATION OF ALVEOLAR EPITHELIAL PHENOTYPIC EXPRESSION

肺泡上皮由两种形态不同的分化上皮细胞组成，I型和II型细胞，这两种细胞都被认为是正常肺功能的关键。虽然正常肺泡上皮的建立和维持对哺乳动物的生命是必不可少的，但控制细胞表型表达的因素还不是很清楚。一般说来，表型表达的调节涉及基因转录的激活和表达。由于缺乏合适的细胞培养模型或独特的细胞特异性生化标记物，使得研究肺组织表型表达的调控变得困难。近年来，在合适的标记和体外系统的开发方面取得了相当大的进展。本项目中的实验涉及肺泡上皮表型表达的调节，重点是I型和II型细胞表型特异性标记物的表达，包括体外和体内。在以前的出版物和项目3和4的进展报告中记录的最新观察表明，机械因素在调节肺泡上皮表型表达方面发挥着重要作用。这项提案的广泛目标有两个：1)定义决定RTI40器官和细胞特异性的调控元件，RTI40在肺内是I型细胞的特异性标记；2)定义机械因素在体外调节细胞表型表达的机制。具体目的1.确定指导组织和细胞特异性表达的RT140基因区域。2.确定调节RTI40表达的顺式作用元件和反式作用因子。3.阐明SP-C和RT140转录的机械敏感调控元件。4.确定在I型和II型细胞中最有可能参与事件机械转导的一些信号通路。

The alveolar epithelium is comprised of 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 a normal alveolar epithelium is essential for mammalian life, factors controlling the expression of cellular phenotype are not well understood. In general, the regulation of phenotypic expression involves both activation and expression of gene transcription. Lack of suitable cell culture models or unique cell-specific biochemical markers has made it difficult to study regulation of phenotypic expression in the lung. In recent years, considerable progress has been made in the development of appropriate markers and in vitro systems. The experiments describes in this project concern the regulation of phenotypic expression of the alveolar epithelium, focusing on the expression of type I and type II cell phenotype- specific markers, both in vitro and in vivo. Recent observations, documented in previous publications and in the Progress Reports to Projects 3 and 4, suggest that mechanical factors play an important role in regulating alveolar epithelial phenotypic expression. The broad objectives of this proposal are two-fold: 1) to define the regulatory elements that dictate organ and cell- specificity for RTI40, which, within the lung, is a specific marker for type I cells; and 2) to define the mechanisms by which mechanical factors modulate cell phenotypic expression in vitro. SPECIFIC AIMS 1. To determine the regions of the RT140 gene that direct tissue and cell- specific expression. 2. To determine the cis-acting elements and trans-acting factors responsible for regulating expression of RTI40. 3. To elucidate the elements responsible for mechanosensitive regulation of transcription of SP-C and RT140. 4. To identify some of the signaling pathways most likely to be involved in mechanical transduction of events in type I and type II cells.