title: N4-monobutyryl-cCMP activates PKA RIα and PKA RIIα more potently and with higher efficacy than PKG Iα in vitro but not in vivo.
abstract: There is increasing evidence for a role of cytidine 3',5'-cyclic monophosphate (cCMP) as second messenger. In a recent study, we showed that cCMP activates both purified guanosine 3',5'-cyclic monophosphate (cGMP)-dependent protein kinase Iα (PKG Iα) and adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) isoenzymes with the regulatory subunits RIα and RIIα. Moreover, the membrane-permeant cCMP analog dibutyryl (DB)-cCMP induces effective vasodilation and inhibition of platelet aggregation via PKG Iα, but not via PKA. These data prompted us to conduct a systematic analysis of the effects of cyclic nucleotide (cNMP) analogs on purified PKG Iα and PKA RIα and RIIα We also studied the effect of DB-cCMP on PKA-dependent phosphorylation of the transcription factor cAMP response-binding protein (CREB) in S49 wild-type lymphoma cells and S49 kin(-) cells, devoid of the catalytic subunit of PKA. The major cellular metabolite of the prodrug DB-cCMP, N(4)-monobutyryl (4-MB)-cCMP, was a partial and low-potency activator of purified PKG Iα and a full and moderate-potency activator of PKA RIα and RIIα. Sp-cCMPS and Sp-cAMPS activated PKA RIα and RIIα with much higher potency and efficacy than PKG Iα. Molecular modeling suggested that the cytidine ring interacts with PKG Iα mainly via hydrophobic interactions, while the butyryl group projects away from the kinase. In contrast to DB-cAMP, DB-cCMP did not induce PKA-dependent phosphorylation in intact cells. Taken together, our data show that N(4)-monobutyryl-cCMP (4-MB-cCMP) activates PKA RIα and PKA RIIα more potently and with higher efficacy than PKG Iα in vitro but not in vivo. cNMP phosphorothioates constitute a starting point for the development of PKA activators with high selectivity relative to PKG.
authors.affiliation: Institute of Pharmacology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625, Hannover, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Wolter
authors.forename: Stefan
authors.initials: S
authors.lastname: Dove
authors.forename: Marina
authors.initials: M
authors.lastname: Golombek
authors.forename: Frank
authors.initials: F
authors.lastname: Schwede
authors.forename: Roland
authors.initials: R
authors.lastname: Seifert
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit / Q000378:metabolism*; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003563:Cyclic CMP / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008223:Lymphoma / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D010766:Phosphorylation / Q000187:drug effects
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; C000599451:N4-monobutyrylcytidine 3',5'-cyclic monophosphate; D003563:Cyclic CMP; C053441:dibutyryl cyclic-3',5'-cytidine monophosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D062965:Cyclic GMP-Dependent Protein Kinase Type I