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 was cloned by screening a newborn guinea pig lung cDNA library with a human 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 sequence levels with those from other species. As expected, guinea pig SP-A mRNA is abundantly expressed in adolescent lung tissue and is undetectable in nonpulmonary tissues. In situ hybridization studies clearly 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 alveolar epithelium with no expression in the bronchiolar epithelial cells, whereas SP-B mRNA is expressed in both alveolar and bronchiolar epithelial cell populations. This distinct expression pattern suggests that the guinea pig lung will be a useful model in which to study expression of transcription factors implicated in the regulation of SP genes.