DESCRIPTION (Applicant's Abstract): Over 20 organisms, including plants, bacteria, and fruit flies have had their entire chromosome contents decoded. By 2003, the entire dog, mouse and human genomes will be known. Biologists of the 21St century are now faced with the challenge of interpreting this genetic information and analyzing how specific gene products - the individual proteins- modulate tissue- and organ-specific functions. We propose to train student investigators to characterize the expression and potential interactions of a novel mouse gene product, recently named plunc. Plunc messenger RNA is expressed at unusually high levels in restricted areas of the mouse nasal, tracheal and bronchial epithelium. Plunc itself appears to be a secreted protein of unknown function with the potential for dimerization or protein-protein interactions. Because the respiratory epithelium of the upper airway is the first organ encountered by inhaled air, the restricted expression of a novel protein in this region raises the question of how the protein might contribute to differentiating, maintaining, or possibly protecting the airway. More recently, partial human, rat and bovine sequences have been cloned, indicating that the plunc protein may be conserved in the tracheal epithelium of air-breathing organisms. although this conservation of genetic structure and tissue-specific expression implies conservation of protein function, little is known about the developmental or physiological role of plunc in any living animal. To investigate the function of this protein in the mammalian respiratory system we will analyze where and when this protein is expressed by lung epithelial cells both in vivo and in vitro. Three specific aims are proposed: 1) to observe the in situ expression pattern of plunc in developing mouse lungs and its correlation with epithelial cell differentiation, 2) to tag and track the secretion of plunc protein in cultured lung cell lines, and 3) to investigate the potential interactions of plunc protein by a) performing protein precipitations to see if plunc interacts with other endogenous proteins in the lung environment, and b) to see if the level of plunc mRNA is temporally regulated when epithelial cells are exposed to exogenous stressors, including toxins and inflammatory agents. Taken together, these studies will provide a wealth of basic science information on this novel lung protein. They will also serve as a comprehensive training program for students seeking experience in molecular biology, developmental biology and protein biochemistry.