Dexamethasone affects phosphatidylinositol synthesis and degradation in cultured human embryonic cells

Dexamethasone (DEX), a glucocorticoid which induces cleft palate, causes marked alterations in the synthesis and degradation of phosphatidylinositol (PI) but not phosphatidylcholine in an established fibroblastic cell line derived from a human embryonic palate. Incorporation of radiolabeled inositol into phosphatidylinositol as well as degradation of prelabeled phosphatidylinositol is stimulated by DEX. The dose-response curves for the DEX-induced effect on PI synthesis and DEX-induced inhibition of cell proliferation are nearly identical, with the maximal responses occurring at 10(-8)M DEX. Our results suggest that DEX-induced inhibition of human embryonic palatal mesenchyme cell proliferation and alterations in synthesis and degradation of phosphatidylinositol are related.