Effect of retinoic acid treatment of F9 embryonal carcinoma cells on the activity and distribution of cyclic AMP-dependent protein kinase.

Treatment of F9 teratocarcinoma cells with all transretinoic acid previously has been shown to induce differentiation to parietal endoderm and to enhance the responsiveness of these cells to the addition of cyclic AMP. Evidence is presented that retinoic acid treatment of F9 cells causes an increase in both cytosolicand plasma membrane-associated cyclic AMP-dependent protein kinase activities. Retinoic acid elicits a progressive increase in cytosolic kinase activity through 72 h. Cyclic AMP-dependent kinase activity of the plasma membrane fraction is enhanced within 3 h of retinoid treatment of F9 cells and reaches a maximum at 15 h after the addition of retinoic acid. The amount of regulatory subunits of cyclic AMPdependent protein kinases I (RI) and I1 (RE) present in the subcellular fractions was quantitated by photoaffmity labeling with 8-azido-cyclic [3’P]AMP. In the cytosol, the amount of RI and RE both increase with the period of retinoid treatment through 24 h, and remain elevated through 5 days; the ratio of RI/RII (-2.5) found in the cytosol remains constant following retinoic acid treatment. RI is much more prevalent than RE (RI/RE = 7.5) in the plasma membrane prepared from untreated F9 cells. Retinoic acid treatment elicits a preferential increase in the amount of the RII regulatory subunit associated with the membrane fraction. After 15 h of retinoid treatment, a 1.6-fold increase in RI is observed, while membrane-associated RE is increased 4.5-fold. After 24 h of retinoic acid treatment, the level of RI returns toward the level noted with untreated cells, while the amount of Ru remains significantly elevated through 5 days of retinoid treatment. These findings suggest that the increase in cyclic AMP-dependent protein kinase activity and the specific accumulation of RE associated with the plasma membrane fraction may be early events of retinoic acid action to mediate eventual cellular differentiation.