title: The modulation of transcobalamin II (TC-II) production by cyclic adenosine 3',5'-monophosphate in the murine macrophage cell line J774: relationship to growth behavior.
abstract: We undertook a study to define the role of cyclic AMP [cAMP] in modulating the secretion of transcobalamin II (TC-II) in the mouse macrophage like cell line J774. J774 was observed to secrete large amounts of TC-II, particularly in the presence of 8-bromo cAMP or cholera toxin or when grown in medium supplemented with low concentrations of horse serum (1% or 5%) or in serum-free medium. Variant cell lines derived from J774 and deficient either in adenylate cyclase (ac -) or cAMP-dependent protein kinase (pk -) activity showed very low and intermediate levels of basal secretory activity of TC-II, respectively, compared to J774. Maximum secretory activity of TC-II was observed in J774 under conditions in which growth was poorest (in the presence of 8-bromo-cAMP or 1% or 5% horse serum-supplemented medium or in serum-free medium). Cells grown in serum-free medium were found to have elevated basal adenylate cyclase activity and cAMP levels compared to those grown in medium supplemented with 20% horse serum. The data from this study demonstrate a negative correlation between growth activity and TC-II secretion in the J774 cell line. The stimulatory effect of exogenous cAMP on TC-II secretion by J774, the reduced secretory activity of the variant lines ac- and pk- and the observed increase in cell cAMP levels under conditions of serum starvation in which TC-II secretion is considerably enhanced, suggest that cell cAMP is an important modulator of TC-II secretion and growth behavior in the J774 cell line.
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001769:Blood; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D006736:Horses; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects; D051379:Mice; D011494:Protein Kinases / Q000378:metabolism; D014155:Transcobalamins / Q000096:biosynthesis*
chemical_list: D014155:Transcobalamins; D015124:8-Bromo Cyclic Adenosine Monophosphate; D002772:Cholera Toxin; D000242:Cyclic AMP; D011494:Protein Kinases; D000262:Adenylyl Cyclases