title: Cyclic AMP induces integrin-mediated cell adhesion through Epac and Rap1 upon stimulation of the beta 2-adrenergic receptor.
abstract: cAMP controls many cellular processes mainly through the activation of protein kinase A (PKA). However, more recently PKA-independent pathways have been established through the exchange protein directly activated by cAMP (Epac), a guanine nucleotide exchange factor for the small GTPases Rap1 and Rap2. In this report, we show that cAMP can induce integrin-mediated cell adhesion through Epac and Rap1. Indeed, when Ovcar3 cells were treated with cAMP, cells adhered more rapidly to fibronectin. This cAMP effect was insensitive to the PKA inhibitor H-89. A similar increase was observed when the cells were transfected with Epac. Both the cAMP effect and the Epac effect on cell adhesion were abolished by the expression of Rap1-GTPase-activating protein, indicating the involvement of Rap1 in the signaling pathway. Importantly, a recently characterized cAMP analogue, 8-(4-chloro-phenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate, which specifically activates Epac but not PKA, induced Rap-dependent cell adhesion. Finally, we demonstrate that external stimuli of cAMP signaling, i.e., isoproterenol, which activates the G alpha s-coupled beta 2-adrenergic receptor can induce integrin-mediated cell adhesion through the Epac-Rap1 pathway. From these results we conclude that cAMP mediates receptor-induced integrin-mediated cell adhesion to fibronectin through the Epac-Rap1 signaling pathway.
authors.affiliation: Department of Physiological Chemistry and Centre for Biomedical Genetics, University Medical Center Utrecht, Netherlands.
authors.forename: Savithri
authors.initials: S
authors.lastname: Rangarajan
authors.forename: Jorrit M
authors.initials: JM
authors.lastname: Enserink
authors.forename: H Bea
authors.initials: HB
authors.lastname: Kuiperij
authors.forename: Johan
authors.initials: J
authors.lastname: de Rooij
authors.forename: Leo S
authors.initials: LS
authors.lastname: Price
authors.forename: Frank
authors.initials: F
authors.lastname: Schwede
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Bos
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000378:metabolism; D002277:Carcinoma; D002448:Cell Adhesion / Q000502:physiology*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D007545:Isoproterenol / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010051:Ovarian Neoplasms; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D014407:Tumor Cells, Cultured; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000318:Adrenergic beta-Agonists; D017362:Cyclic AMP Response Element-Binding Protein; D005353:Fibronectins; D020662:Guanine Nucleotide Exchange Factors; D016023:Integrins; C116122:RAPGEF3 protein, human; D018343:Receptors, Adrenergic, beta-2; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020827:rap1 GTP-Binding Proteins; D007545:Isoproterenol