title: cAMP-induced Epac-Rap activation inhibits epithelial cell migration by modulating focal adhesion and leading edge dynamics.
abstract: Epithelial cell migration is a complex process crucial for embryonic development, wound healing and tumor metastasis. It depends on alterations in cell-cell adhesion and integrin-extracellular matrix interactions and on actomyosin-driven, polarized leading edge protrusion. The small GTPase Rap is a known regulator of integrins and cadherins that has also been implicated in the regulation of actin and myosin, but a direct role in cell migration has not been investigated. Here, we report that activation of endogenous Rap by cAMP results in an inhibition of HGF- and TGFbeta-induced epithelial cell migration in several model systems, irrespective of the presence of E-cadherin adhesion. We show that Rap activation slows the dynamics of focal adhesions and inhibits polarized membrane protrusion. Importantly, forced integrin activation by antibodies does not mimic these effects of Rap on cell motility, even though it does mimic Rap effects in short-term cell adhesion assays. From these results, we conclude that Rap inhibits epithelial cell migration, by modulating focal adhesion dynamics and leading edge activity. This extends beyond the effect of integrin affinity modulation and argues for an additional function of Rap in controlling the migration machinery of epithelial cells.
authors.affiliation: Department of Physiological Chemistry, Centre for Biomedical Genetics and Cancer Genomics Centre, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands.
authors.forename: Karen S
authors.initials: KS
authors.lastname: Lyle
authors.forename: Judith H
authors.initials: JH
authors.lastname: Raaijmakers
authors.forename: Wytse
authors.initials: W
authors.lastname: Bruinsma
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Bos
authors.forename: Johan
authors.initials: J
authors.lastname: de Rooij
mesh_terms: D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D022001:Focal Adhesions / Q000201:enzymology* / Q000648:ultrastructure; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D017228:Hepatocyte Growth Factor / Q000037:antagonists & inhibitors; D006801:Humans; D016023:Integrins / Q000378:metabolism; D007365:Intercellular Junctions / Q000502:physiology; D011554:Pseudopodia / Q000648:ultrastructure; D015398:Signal Transduction; D020668:rap GTP-Binding Proteins / Q000378:metabolism*
chemical_list: C473217:8-(4-chloro-phenylthio)-2'-O-methyladenosine-3'-5'-cyclic monophosphate; D020662:Guanine Nucleotide Exchange Factors; D016023:Integrins; C116122:RAPGEF3 protein, human; D017228:Hepatocyte Growth Factor; D000242:Cyclic AMP; D020668:rap GTP-Binding Proteins