Stimulation of Ribonucleic Acid Synthesis in Horse Lymphocytes by Exogenous Cyclic Adenosine 3′,5′-Monophosphate

• Published in: The Journal of biological chemistry 1972-01, Vol.247 (2), p.413-417
• Main Authors: Averner, Melvin J., Brock, M. Louise, Jost, Jean-Pierre
• Format: Article
• Language: English
• Subjects: animal science; livestock; zoology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)45719-0

At concentrations of 10-4 to 10-5m, cyclic adenosine 3′,5′-monophosphate (cyclic AMP) stimulated the incorporation of radioactive uridine into RNA in horse lymphocytes but did not stimulate the incorporation of radioactive thymidine into DNA. In either the absence or in the presence of a saturating concentration of phytohemagglutinin, cyclic 3′,5′-AMP increased the rate of RNA synthesis by 40 to 50%. In contrast, N6, O2′-dibutyryl 3′,5′-cyclic AMP inhibited RNA synthesis whereas N6-monobutyryl cyclic 3′,5′-AMP had a slight stimulatory effect. At 10-4m, cyclic 3′,5′-AMP does not affect the rate of uridine uptake in to the trichloroacetic acid-soluble pool, the synthesis of uridine triphosphate, or the rate of RNA degradation. It is concluded that cyclic 3′,5′-AMP exerts a direct effect upon transcription and that phytohemagglutinin does not induce lymphocyte transformation by a simple effect upon the endogenous level of cyclic 3′,5′-AMP.