Enserink, J.M. et al. A novel Epac-specific cAMP analogue demonstrates independent regulation of Rap1 and ERK. Nat. Cell Biol. 4, 901-906

University of Bergen, Bergen, Hordaland, Norway
Nature Cell Biology (Impact Factor: 19.68). 12/2002; 4(11):901-6. DOI: 10.1038/ncb874
Source: PubMed


cAMP is involved in a wide variety of cellular processes that were thought to be mediated by protein kinase A (PKA). However, cAMP also directly regulates Epac1 and Epac2, guanine nucleotide-exchange factors (GEFs) for the small GTPases Rap1 and Rap2 (refs 2,3). Unfortunately, there is an absence of tools to discriminate between PKA- and Epac-mediated effects. Therefore, through rational drug design we have developed a novel cAMP analogue, 8-(4-chloro-phenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (8CPT-2Me-cAMP), which activates Epac, but not PKA, both in vitro and in vivo. Using this analogue, we tested the widespread model that Rap1 mediates cAMP-induced regulation of the extracellular signal-regulated kinase (ERK). However, both in cell lines in which cAMP inhibits growth-factor-induced ERK activation and in which cAMP activates ERK, 8CPT-2Me-cAMP did not affect ERK activity. Moreover, in cell lines in which cAMP activates ERK, inhibition of PKA and Ras, but not Rap1, abolished cAMP-mediated ERK activation. We conclude that cAMP-induced regulation of ERK and activation of Rap1 are independent processes.

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    • "To investigate the role of cAMP-dependent protein kinases in the Iso mediated reduction in HDMEC motility, an inhibitor of PKA (rp cAMP (rp)) and an EPAC activator (8-CPT-2 0 -O- Me-cAMP (8-pCPT)) were used. 8-pCPT is a selective agonist for EPAC1 (Enserink et al., 2002) that activates EPAC1 with a higher affinity (EC 50 2.2 mM) than cAMP (EC 50 30 mM) but has no effect on PKA (Enserink et al., 2002). "
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    • "Rats received a bilateral infusion (0.25 µl/min, for 2 min) into the BLA [20] and the injectors remained in place for 2 min following the infusion to allow for diffusion of the solution. In experiments 1, 2, 3, and 5, the experimental groups received infusions of the Epac-specific agonist [28] (8-(4-chlorophenylthio)-2′-O-methyladenosine-3′, 5′-cyclic monophosphate (8-CPT, 7.5 or 10 nmol per side, Sigma-Aldrich). In experiment 4a, the experimental group received infusions of a mixture of 8-CPT (10 nmol per side) and the PKA-specific activator 6-Bnz-cAMP (10 nmol per side) [29]. "
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