SCRENING OF IN NEW-BORN RAT LUNG GENES RESPONDING TO OXYGEN TENSION SHIFT

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At birth, mammals are exposed to oxygen tension shift from low O2 in the uterus (PO2 is 12 Torr) to high O2 in atmospheric environment (PO2 is more than 100 Torr). Especially, the lung epithelium receives drastic increase in oxygen tension at the beginning of respiration. In this study, we screened the genes which respond to oxygen tension shift using the fluorescent differential display method in order to explore the adaptation mechanism of mammals to oxygen tension shift.Fibroblast isolated from fetal rat lung and SV40 immortalized type 2 alveolar epithelial cell were cultured at various oxygen tension. Total RNA was isolated from these cells before and after exposures to hypoxia. After RT-PCR amplification with FITC-labeled anchor primers and arbitrary primers, DNA fragments were separated by 6% PAGE and analyzed by Pharmacia Fragment Manager or autoradiography.Four DNA fragments were differentially expressed by hypoxia and three of them have the sequence identical to 3' end of aldolase a, phosphoglycerate mutase type B subunit and prolyl 4-hydroxylase. The last DNA fragment showed no homology to any genes in data bank.Prolyl 4-hydroxylase was up-regulated by hypoxia and down-regulated by oxygen tension shift from hypoxia to normoxia. Furthermore, the RNA was more abundant in the fetal lung than in the adult lung. These data suggest that collagen metabolism may be regulated by oxygen tension.