PHOSPHOLIPID-TRANSFER PROTEINS AND THEIR MESSENGER-RNAS IN DEVELOPINGRAT LUNG AND IN ALVEOLAR TYPE-II CELLS

Gene expression of non-specific lipid-transfer protein (nsL-TP; identi cal with sterol carrier protein 2) and phosphatidylinositol-transfer p rotein (PI-TP) was investigated in developing rat lung. During the lat e prenatal period (between days 17 and 22) there is a 7-fold increase in the level of nsL-TP and a 2-fold rise in that of PI-TP. The prenata l increases in the levels of nsL-TP and PI-TP are accompanied by paral lel increases in the levels of their mRNAs, indicating pretranslationa l regulation. Compared with whole lung, isolated alveolar type-II cell s are enriched in nsL-TP and its mRNA, but not in PI-TP and its mRNA. The observation that the levels of nsL-TP and its mRNA in rat lung sho w a pronounced increase in the period of accelerated surfactant format ion, together with the observation that the surfactant-producing type- II cells are enriched in nsL-TP and its mRNA, suggest that nsL-TP play s a role in the metabolism of pulmonary surfactant.