CLONING OF GUINEA-PIG SURFACTANT PROTEIN-A DEFINES A DISTINCT CELLULAR-DISTRIBUTION PATTERN WITHIN THE LUNG

A full-length cDNA to guinea pig pulmonary surfactant protein (SP) A w as cloned by screening a newborn guinea pig lung cDNA library with a h uman SP-A cDNA probe. The full-length guinea pig SP-A cDNA consists of 1,839 bp and is highly conserved at both nucleotide and amino acid se quence levels with those from other species. As expected, guinea pig S P-A mRNA is abundantly expressed in adolescent lung tissue and is unde tectable in nonpulmonary tissues. In situ hybridization studies clearl y show a unique cellular distribution pattern of SP-A mRNA within the guinea pig lung. SP-A mRNA expression is confined to cells of the alve olar epithelium with no expression in the bronchiolar epithelial cells , whereas SP-B mRNA is expressed in both alveolar and bronchiolar epit helial cell populations. This distinct expression pattern suggests tha t the guinea pig lung will be a useful model in which to study express ion of transcription factors implicated in the regulation of SP genes.