title: Serum-stimulated cyclic-AMP production in S49 lymphoma cells grown in serum-free medium.
abstract: Growth of S49 lymphoma cells with horse serum leads to an increase in cellular cAMP phosphodiesterase activity and a resultant loss of hormone- and cholera-toxin-stimulated cAMP accumulation. We now show that the serum requires protein synthesis to produce these effects. Further, we show that acute addition of serum to wild-type S49 cells, grown in serum-free medium, rapidly (under 2 min) and transiently (under 30 min) stimulates cellular cAMP, 10-fold over basal levels. This 'acute' effect of serum was not observed in UNC S49 cells, suggesting that a functional Ns, the guanine nucleotide regulatory component that mediates stimulation of adenylate cyclase, is required for the serum-mediated stimulation of cellular cAMP. Serum added acutely to wild-type S49 cells also augmented cAMP accumulation in response to isoproterenol and forskolin. The half-maximally effective concentrations of horse serum that acutely stimulated or more slowly decreased the cAMP accumulation were approx. 0.2% and 2.0%, respectively. Preliminary attempts to characterize further the serum factor indicate that it has a high (250 000-300 000) molecular weight and is insensitive to boiling; chromatography on Sepharose CL-6B yields a 100-fold purification. Thus, the serum contains one or more components that activate adenylate cyclase, increase cellular cAMP levels and ultimately induce cAMP phosphodiesterase in S49 lymphoma cells.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001769:Blood; D002460:Cell Line; D005576:Colforsin; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism*; D004224:Diterpenes / Q000494:pharmacology; D006736:Horses; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008223:Lymphoma / Q000378:metabolism*; D051379:Mice
chemical_list: D000959:Antihypertensive Agents; D003470:Culture Media; D004224:Diterpenes; D005576:Colforsin; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D007545:Isoproterenol