IDENTIFICATION AND CHARACTERIZATION OF MATERIALS SECRETED BY CLARA CELLS

细支气管Clara细胞的功能尚不清楚 尽管通常认为该细胞是分泌性的。 使用 一个模型系统，在这个实验室开发，我们已经确定了一个 低分子量蛋白质（Mr 12，500）为主要蛋白质 由克拉拉细胞分泌 我们还确认了 分泌的一个简单的程序，其分离。 抗血清 针对高度纯化的Clara细胞（纯度 大于90%）已被用于定位Clara细胞分泌 嗜锇细胞质颗粒内的蛋白质 细支气管Clara细胞显示了 颗粒和低分子量蛋白质分泌 可能是通过一个受调控的途径发生的。 我们还分离出了 从兔肺中提取mRNA，并证明了原发性 翻译产物的分子量大约1 kDa 而不是分泌的蛋白质。 另外的肽是 信号肽，如由其在以下情况下从分子中丢失所指示的： 使者的翻译是在 微粒体 这些研究确定了主要的分泌蛋白 Clara细胞的低分子量蛋白质， 储存在细胞质嗜锇颗粒中。 我们有 还研究了Clara细胞的分化潜能， 将纯化的细胞植入大鼠气管， 上皮细胞 然后将这些气管移植到 裸鼠，并定期检查再生的 上皮 我们已经确定克拉拉细胞可以繁殖， 产生由Clara细胞和纤毛组成的上皮 细胞，从而建立了这个细支气管的干细胞性质， cell. 未来的研究将探索克拉拉细胞的能力， 使用气管移植物模型分化成毛细胞， 关注低分子量的细胞外功能 分泌蛋白

The functions of the bronchiolar Clara cell are not known although it is generally believed that the cell is secretory. Using a model system, developed in this laboratory, we have identified a low molecular weight protein (Mr 12,500) as the major protein secreted by Clara cells. We have also identified the major secretory a simple procedure for its isolation. Antiserum developed in goats against highly purified Clara cells (purity greater than 90%) has been used to localize Clara cell secretory proteins within the osmiophilic cytoplasmic granules of bronchiolar Clara cells indicating the storage nature of the granules and that secretion of the low molecular weight protein probably occurs via a regulated pathway. We have also isolated mRNA from rabbit lungs and demonstrated that the primary translation product has a molecular weight about 1 kDa larger than the secreted form of the protein. The additional peptide was a signal peptide as indicated by its loss from the molecule when translation of the messenger was performed in the presence of microsomes. These studies identify the major secretory protein of Clara cells as a low molecular weight protein that appears to be stored within the cytoplasmic osmiophilic granules. We have also investigated the differentiative potential of Clara cells by inoculating purified cells into rat trachea denuded of their own epithelia. These trachea were then grafted onto the backs of nude mice and examined periodically for regeneration of epithelium. We have determined that Clara cells can multiply and generate an epithelium which consists of Clara cells and ciliated cells thus establishing the stem cell nature of this bronchiolar cell. Future studies will explore the ability of Clara cells to differentiate into mocous cells using the tracheal graft model and focus on the extracellular function of the low molecular weight secretory protein.