Identification of a Novel, Small Molecule Partial Agonist for the Cyclic AMP Sensor, EPAC1.
Screening of a carefully selected library of 5,195 small molecules identified 34 hit compounds that interact with the regulatory cyclic nucleotide-binding domain (CNB) of the cAMP sensor, EPAC1. Two of these hits (I942 and I178) were selected for their robust and reproducible inhibitory effects within the primary screening assay. Follow-up characterisation by ligand observed nuclear magnetic resonance (NMR) revealed direct interaction of I942 and I178 with EPAC1 and EPAC2-CNBs in vitro. Moreover, in vitro guanine nucleotide exchange factor (GEF) assays revealed that I942 and, to a lesser extent, I178 had partial agonist properties towards EPAC1, leading to activation of EPAC1, in the absence of cAMP, and inhibition of GEF activity in the presence of cAMP. In contrast, there was very little agonist action of I942 towards EPAC2 or protein kinase A (PKA). To our knowledge, this is the first observation of non-cyclic-nucleotide small molecules with agonist properties towards EPAC1. Furthermore, the isoform selective agonist nature of these compounds highlights the potential for the development of small molecule tools that selectively up-regulate EPAC1 activity.
Institute of Molecular, Cellular and Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
Euan
E
Parnell
European Screening Centre, University of Dundee, Biocity Scotland, Newhouse, ML1 5UH, UK.
Stuart P
SP
McElroy
Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh Campus, Edinburgh, EH14 4AS, UK.
Jolanta
J
Wiejak
European Screening Centre, University of Dundee, Biocity Scotland, Newhouse, ML1 5UH, UK.
Gemma L
GL
Baillie
European Screening Centre, University of Dundee, Biocity Scotland, Newhouse, ML1 5UH, UK.
Alison
A
Porter
Institute of Chemical Sciences, Heriot-Watt University, Edinburgh Campus, Edinburgh, EH14 4AS, UK.
David R
DR
Adams
Department of Molecular Cancer Research, Centre of Biomedical Genetics and Cancer Genomics Centre, University Medical Centre Utrecht, Utrecht, The Netherlands.
Holger
H
Rehmann
Institute of Molecular, Cellular and Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
Brian O
BO
Smith
Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh Campus, Edinburgh, EH14 4AS, UK. S.Yarwood@hw.ac.uk.
Stephen J
SJ
Yarwood
D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D020662:Guanine Nucleotide Exchange Factors / Q000819:agonists*; D009682:Magnetic Resonance Spectroscopy; D009711:Nucleotides / Q000302:isolation & purification* / Q000378:metabolism*; D011485:Protein Binding
D020662:Guanine Nucleotide Exchange Factors; D009711:Nucleotides; C116122:RAPGEF3 protein, human; C442864:RAPGEF4 protein, human; D017868:Cyclic AMP-Dependent Protein Kinases