SIGNALING PATHWAYS REGULATING ORNITHINE DECARBOXYLASE ACTIVITY IN THEEMBRYONIC CHICKEN

The pathways regulating ornithine decarboxylase (ODC) activity in the chick embryo were studied to determine which kinase-signaling pathways regulate ODC activity levels during development. Insulin-dependent ty rosine kinase, protein kinase C and cAMP-dependent protein kinase were activated by the addition of insulin, tetradecanoylphorbol-12,13-acet ate, and forskolin, respectively. All three drugs increased ODC activi ty and forskolin combined with insulin increased ODC activity above th e increase caused by either drug alone. These results suggest that all three signaling pathways regulate ODC activity during development and that common intermediates exist among the pathways downstream of the kinases.