Abstract
EGF is believed to enhance fetal lung maturation. We have examined the interactions between EGF and corticosteroids in ex-plants of fetal rat lung in a serum free organ culture system. EGF stimulated the incorporation of choline into phosphatidylcholine (PC) and disaturated PC (DSPC) in a dose dependent fashion with half the maximal effect occurring at 1.03 nM (6.31 ng/ml). There was also a 6 fold increase in acetate incorporation into phosphatidylglycerol. T3 and EGF together had an additive effect on choline incorporation into DSPC, whereas exposure to saturating doses of EGF plus dexamethasone (dex) had no greater effect than did dex alone, suggesting that the 2 agents act at similar metabolic sites.
We further explored the interaction between EGF and dex. Dex increased the activity of cholinephosphate cytidylyltransferase, the rate limiting enzyme of PC synthesis, but EGF had no effect on this enzyme. We also examined the influence of dex on EGF binding and separately that of EGF on glucocorticoid binding. EGF had no effect on specific cytoplasmic or nuclear glucocorticoid binding, but exposure to dex resulted in a 2 fold increase in specific EGF binding capacity.
One of the ways in which corticosteroids stimulate lung maturation may be by increasing EGF binding capacity with subsequent amplification of EGF action.
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Gross, I., Dynia, D., Rooney, S. et al. 270 IS EGF A MEDIATOR OF GLUCOCORTICOID ACTION ON DEVELOPING FETAL LUNG?. Pediatr Res 19, 155 (1985). https://doi.org/10.1203/00006450-198504000-00300
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DOI: https://doi.org/10.1203/00006450-198504000-00300