The (R)-enantiomer of CE3F4 is a preferential inhibitor of human exchange protein directly activated by cyclic AMP isoform 1 (Epac1)

Delphine Courilleau (1) , Pascal Bouyssou (2) , Rodolphe Fischmeister (3, 4) , Frank Lezoualc’h (5) , Jean-Paul Blondeau (1)

1 IFRH / RFRH - Institut fédératif de recherche sur le handicap / Réseau fédératif de recherche sur le handicap
2 ICOA - Institut de Chimie Organique et Analytique
3 Signalisation et physiopathologie cardiaque
4 LabEx LERMIT - Laboratoire d'Excellence en Recherche sur le Médicament et l'Innovation Thérapeutique [Châtenay-Malabry]
5 I2MC - Institut des Maladies Métaboliques et Cardiovasculaires

Isoform 1 and isoform 2 of exchange protein directly activated by cAMP (Epac1 and Epac2) contribute to cAMP signaling in numerous cellular processes. Their guanine-nucleotide exchange factor (GEF) activity toward the small GTP-binding protein Rap1 is stimulated by the agonist cAMP. CE3F4, a tetrahydroquinoline analog, prevents Epac1 activation in vitro and in living cultured cells by inhibiting the GEF activity of Epac1. However, the activity of the (R)-and (S)-enantiomers of CE3F4, as well as the ability of CE3F4 and its analogs to inhibit Epac2 GEF activity, have not yet been investigated. In this study, we report that (R)-CE3F4 is a more potent cAMP antagonist than racemic CE3F4 and (S)-CE3F4, inhibiting the GEF activity of Epac1 with 10-times more efficiency than (S)-CE3F4. Epac2, in contrast to Epac1, is activated more efficiently by cAMP than by 8-(4-chlorophenylthio)-2'-Omethyladenosine-3',5'-cyclic monophosphate (007), an Epac-selective cAMP analog. (R)-CE3F4 displays Epac isoform preference, with 10-fold selectivity for Epac1 over Epac2. Deletion of the N-terminal cyclic nucleotide-binding domain of Epac2 does not affect the characteristics of activation of Epac2 by cAMP and by 007, nor its inhibition by CE3F4. Finally, the evaluation of a series of CE3F4 structural analogs as GEF inhibitors allowed identifying structural features that are important for high Epac1 inhibitory activity of CE3F4. We conclude that the (R)-enantiomer of CE3F4 is a preferential inhibitor of Epac1 with high potency in the low micromolar range, and we suggest that this compound may be a useful pharmacological tool for investigating the functional role of Epac1 in cAMP signaling.

Mots clés: cAMP signaling; Epac inhibitor; Rap1 GEF; tetrahydroquinoline analogs; drug enantiomers.; cAMP signaling

Domaines: Biochimie, Biologie Moléculaire

Delphine Courilleau, Pascal Bouyssou, Rodolphe Fischmeister, Frank Lezoualc’h, Jean-Paul Blondeau. The (R)-enantiomer of CE3F4 is a preferential inhibitor of human exchange protein directly activated by cyclic AMP isoform 1 (Epac1). Biochemical and Biophysical Research Communications, 2013, 440 (3), pp.443-448. ⟨10.1016/j.bbrc.2013.09.107⟩. ⟨hal-03620245⟩