Coordination between membrane trafficking and actin polymerization is fundamental in cell migration, but a dynamic view of the underlying molecular mechanisms is still missing. The Rac1 GTPase controls actin polymerization at protrusions by interacting with its effector, the Wave regulatory complex (WRC). The exocyst complex, which functions in polarized exocytosis, has been involved in the regulation of cell motility. Here, we show a physical and functional connection between exocyst and WRC. Purified components of exocyst and WRC directly associate in vitro, and interactions interfaces are identified. The exocyst–WRC interaction is confirmed in cells by co-immunoprecipitation and is shown to occur independently of the Arp2/3 complex. Disruption of the exocyst–WRC interaction leads to impaired migration. By using time-lapse microscopy coupled to image correlation analysis, we visualized the trafficking of the WRC towards the front of the cell in nascent protrusions. The exocyst is necessary for WRC recruitment at the leading edge and for resulting cell edge movements. This direct link between the exocyst and WRC provides a new mechanistic insight into the spatio-temporal regulation of cell migration.
The authors declare no competing or financial interests.
M.B., A.S.-D., G.Z., M.A., M.C.P. performed the biological experiments. P.P.-G., F.W., M.C.P. developed image analysis codes and analyzed the data. E.F. coordinated 2-hybrid screens. M.H., A.G. generated cell lines. J.Y., R.G. performed structural modeling. M.C.P., G.S., J.C., A.G. designed and supervised the experiments. M.C.P. wrote the manuscript. A.S.-D., P.P.-G. and G.Z. made equal contributions to this work, as did G.S., J.C. and M.C.P.
This work was supported by Association pour la Recherche sur le Cancer [grant numbers SFI20121205710 to M.C.P. and SFI20111203931 to J.C.]; Ligue Contre le Cancer [grant number RS14/75-54 to M.C.P.]; Association Christelle Bouillot (to J.C.); GenHomme Network [grant number 02490-6088, to Hybrigenics and Institut Curie); Associazione Italiana per la Ricerca sul Cancro [grant number IG 14104 to G.S.); the European Research Council [grant number 268836 to G.S.]; the Association for International Cancer Research [grant number 14-0335 to G.S.]; and the Fondazione Cariplo (to G.S.). M.B. and A.S.-D. were recipients of fellowships from Association pour la Recherche sur le Cancer, Ligue Contre le Cancer, European Molecular Biology Organization and Vinci program of the Université Franco-Italienne.
Supplementary information available online at http://jcs.biologists.org/lookup/doi/10.1242/jcs.187336.supplemental
- Received February 15, 2016.
- Accepted August 16, 2016.
- © 2016. Published by The Company of Biologists Ltd