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Molecular and Cellular Biology, May 2009, p. 2521-2531, Vol. 29, No. 10
0270-7306/09/$08.00+0 doi:10.1128/MCB.01630-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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Martijn Gloerich,3,
Laila Ritsma,1,3
Holger Rehmann,3
Johannes L. Bos,3* and
Kees Jalink1*
Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands,1 Division of Cellular Biochemistry and Centre of Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands,2 Department of Physiological Chemistry, Centre of Biomedical Genetics and Cancer Genomics Centre, University Medical Center Utrecht, Utrecht, The Netherlands3
Received 20 October 2008/ Returned for modification 1 December 2008/ Accepted 27 February 2009
Epac1 is a guanine nucleotide exchange factor (GEF) for the small G protein Rap and is directly activated by cyclic AMP (cAMP). Upon cAMP binding, Epac1 undergoes a conformational change that allows the interaction of its GEF domain with Rap, resulting in Rap activation and subsequent downstream effects, including integrin-mediated cell adhesion and cell-cell junction formation. Here, we report that cAMP also induces the translocation of Epac1 toward the plasma membrane. Combining high-resolution confocal fluorescence microscopy with total internal reflection fluorescence and fluorescent resonance energy transfer assays, we observed that Epac1 translocation is a rapid and reversible process. This dynamic redistribution of Epac1 requires both the cAMP-induced conformational change as well as the DEP domain. In line with its translocation, Epac1 activation induces Rap activation predominantly at the plasma membrane. We further show that the translocation of Epac1 enhances its ability to induce Rap-mediated cell adhesion. Thus, the regulation of Epac1-Rap signaling by cAMP includes both the release of Epac1 from autoinhibition and its recruitment to the plasma membrane.
Published ahead of print on 9 March 2009.
Supplemental material for this article may be found at http://mcb.asm.org/.
These authors contributed equally.
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