The C Terminus of Sprouty Is Important for Modulation of Cellular Migration and Proliferation

Abstract

The Drosophila Sprouty (SPRY) protein has been shown to inhibit the actions of epidermal growth factor and fibroblast growth factor. However, the role of mammalian SPRY proteins has not been clearly elucidated. We postulated that human Sprouty2 (hSPRY2) is an inhibitor of cellular migration and proliferation. Indeed, using stably transfected HeLa cells, which expressed hemagglutinin (HA)-tagged hSPRY2 or hSPRY2 tagged at the C terminus with red fluorescent protein, we demonstrated that hSPRY2 inhibits the migration of cells in response to serum, epidermal growth factor, fibroblast growth factor, and platelet-derived growth factor. Additionally, hSPRY2 also inhibited the growth of HeLa cells in response to serum. Previously, two C-terminal domains on hSPRY2, which are necessary for its colocalization with microtubules (residues 123-177) or translocation to membrane ruffles (residues 178-194), have been identified (Lim, J., Wong, E. S., Ong, S. H., Yusoff, P., Low, B. C., and Guy, G. R. (2000) J. Biol. Chem. 275, 32837-32845). Therefore, using TAT-tagged hSPRY2 and its mutants, we determined the role of these two C-terminal domains in the inhibition of cell migration and proliferation. Our data show that the deletion of either of these two regions in hSPRY2 abrogates its ability to modulate cell migration in response to different growth factors and proliferation in response to serum. Therefore, we conclude that hSPRY2 inhibits the actions of a number of growth factors, and its C terminus, which is homologous among various SPRY isoforms, is important in mediating its biological activity.