CYCLIC-AMP INDUCES ACTIVITY INCREASE OF KINASE FA (A TRANSMEMBRANE SIGNAL OF INSULIN) DURING NG108-15 HYBRID CELL-DIFFERENTIATION

The ATP.Mg-dependent protein phosphatase activating factor (protein kinase Fa) has been identified to exist in neuroblastoma × glioma hybrid 108-15 cells (NG108-15 cells). More importantly, when NG cells were induced to differentiate with N6, O2′-dibutyryl adenosine 3′, 5′-cyclic monophosphate (dibutyryl cAMP), the cellular activity of kinase Fa was found to increase dramatically. Time course study further revealed that induction of differentiation in NG cells by dibutyryl cAMP treatment increased the Fa activity to over 3 times the levels found in undifferentiated cells and in a linear day-dependent manner, indicating that the Fa activity level is correlated with the state of differentiation of NG108-15 cells. This is the first report providing initial evidence that protein kinase Fa (a transmembrane signal of insulin) is involved in the induction of neuronal cell differentiation. © 1990.