Decreased turnover of phosphatidylinositol accompanies in vitro differentiation of embryonic chicken lens epithelial cells into lens fibers.
The in vivo differentiation of embryonic chicken lens epithelial cells into lens fibers is accompanied by a marked decrease in the rate of degradation of phosphatidylinositol. The present experiments were undertaken to determine whether a similar change in phosphatidylinositol metabolism occurs during in vitro lens fiber formation in cultured explants of embryonic chicken lens epithelia. Lens epithelial cells in the explants differentiate into lens fibers following the addition of fetal calf serum, insulin or chicken vitreous humor to the culture medium. The results show that phosphatidylinositol is degraded with a half-life of 3-6 h in cultured lens epithelia that are not stimulated to differentiate. In contrast, no degradation occurs for at least 6 h in lens epithelia stimulated to form lens fibers. The stabilization of phosphatidylinositol is apparent within 4 h after the onset of fiber cell formation, and thus represents an early event in differentiation. The rapid degradation of phosphatidylinositol in lens epithelia is accompanied by comparably rapid synthesis. During this metabolic turnover only the phosphorylinositol portion of the molecule is renewed, as expected if hydrolysis occurs by the action of a phospholipase C, such as phosphatidylinositol phosphodiesterase. Thus, these data suggest that agents which produce in vitro differentiation of embryonic chicken lens epithelial cells into lens fibers lead to a reduction in either the amount or the activity of phospholipase C.
D000818:Animals; D002454:Cell Differentiation; D002642:Chick Embryo; D004247:DNA / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D005990:Glycerol / Q000378:metabolism; D001556:Hexachlorocyclohexane / Q000494:pharmacology; D007294:Inositol / Q000378:metabolism; D007908:Lens, Crystalline / Q000187:drug effects / Q000196:embryology*; D009924:Organ Culture Techniques; D010712:Phosphatidic Acids / Q000096:biosynthesis; D010716:Phosphatidylinositols / Q000378:metabolism*; D014316:Tritium
D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D014316:Tritium; D007294:Inositol; D001556:Hexachlorocyclohexane; D004247:DNA; D005990:Glycerol