WAVE3-mediated Cell Migration and Lamellipodia Formation Are Regulated Downstream of Phosphatidylinositol 3-Kinase

Abstract

WAVE3 is a member of the WASP/WAVE family of protein effectors of actin reorganization and cell movement. The precise role of WAVE3 in cell migration and its regulation, however, have not been elucidated. Here we show that endogenous WAVE3 was found to be concentrated in the lamellipodia at the leading edge of migrating MDA-MB-231 cells. Platelet-derived growth factor (PDGF) treatment induced lamellipodia formation as well as two-dimensional migration of cells in the wound-closure assay and chemotactic migration toward PDGF in three-dimensional migration chambers. Knockdown of WAVE3 expression by RNA interference prevented the PDGF-induced lamellipodia formation and cell migration. Treatment of cells with LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K), also abrogated the PDGF-induced lamellipodia formation and cell migration, suggesting that PI3K may be required for WAVE3 activity. WAVE3 and the PI3K regulatory subunit, p85, were found to interact in a yeast two-hybrid screen, which was confirmed through co-immunoprecipitation. The WAVE3-p85 interaction was mediated by the N-terminal region of WAVE3 and the C-terminal SH2 domain of p85. These results imply that the WAVE3-mediated migration in MDA-MB-231 cells via lamellipodia formation is activated downstream of PI3K and induced by PDGF. The findings of the WAVE3-p85 partnership also suggest a potential regulatory role for p85 in WAVE3-dependent actin-cytoskeleton reorganization and cell migration. WAVE3 is a member of the WASP/WAVE family of protein effectors of actin reorganization and cell movement. The precise role of WAVE3 in cell migration and its regulation, however, have not been elucidated. Here we show that endogenous WAVE3 was found to be concentrated in the lamellipodia at the leading edge of migrating MDA-MB-231 cells. Platelet-derived growth factor (PDGF) treatment induced lamellipodia formation as well as two-dimensional migration of cells in the wound-closure assay and chemotactic migration toward PDGF in three-dimensional migration chambers. Knockdown of WAVE3 expression by RNA interference prevented the PDGF-induced lamellipodia formation and cell migration. Treatment of cells with LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K), also abrogated the PDGF-induced lamellipodia formation and cell migration, suggesting that PI3K may be required for WAVE3 activity. WAVE3 and the PI3K regulatory subunit, p85, were found to interact in a yeast two-hybrid screen, which was confirmed through co-immunoprecipitation. The WAVE3-p85 interaction was mediated by the N-terminal region of WAVE3 and the C-terminal SH2 domain of p85. These results imply that the WAVE3-mediated migration in MDA-MB-231 cells via lamellipodia formation is activated downstream of PI3K and induced by PDGF. The findings of the WAVE3-p85 partnership also suggest a potential regulatory role for p85 in WAVE3-dependent actin-cytoskeleton reorganization and cell migration. Remodeling of the actin cytoskeleton plays a critical role in altering both cellular morphology and motility (1Mitchison T.J. Cramer L.P. Cell. 1996; 84: 371-379Abstract Full Text Full Text PDF PubMed Scopus (1310) Google Scholar) by controlling a range of cellular events, including immune defense, embryonic development, and neuronal outgrowth (2Millard T.H. Sharp S.J. Machesky L.M. Biochem. J. 2004; 380: 1-17Crossref PubMed Scopus (212) Google Scholar, 3Suetsugu S. Takenawa T. Int. Rev. Cytol. 2003; 229: 245-286Crossref PubMed Scopus (57) Google Scholar). In response to extracellular signals such as growth factors, the WASP family of proteins, which contains WASP and N-WASP (4Derry J.M. Ochs H.D. Francke U. Cell. 1994; 79: 635-644Abstract Full Text PDF Scopus (839) Google Scholar), and the WAVE family of proteins, which contains WAVE1, -2, and -3 (5Miki H. Miura K. Matuoka K. Nakata T. Hirokawa N. Orita S. Kaibuchi K. Takai Y. Takenawa T. J. Biol. Chem. 1994; 269: 5489-5492Abstract Full Text PDF PubMed Google Scholar, 6Sossey-Alaoui K. Head K. Nowak N. Cowell J.K. Mamm. Genome. 2003; 14: 314-322Crossref PubMed Scopus (40) Google Scholar, 7Takenawa T. Miki H. J. Cell Sci. 2001; 114: 1801-1809Crossref PubMed Google Scholar), activate the Arp2/3 complex, leading to the stimulation of actin polymerization and assembly (8Mullins R.D. Heuser J.A. Pollard T.D. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6181-6186Crossref PubMed Scopus (1046) Google Scholar, 9Machesky L.M. Mullins R.D. Higgs H.N. Kaiser D.A. Blanchoin L. May R.C. Hall M.E. Pollard T.D. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 3739-3744Crossref PubMed Scopus (616) Google Scholar). The WASP/WAVE families are protein effectors that act downstream of the Rho GTPases to regulate actin polymerization (7Takenawa T. Miki H. J. Cell Sci. 2001; 114: 1801-1809Crossref PubMed Google Scholar). Interactions between members of the WASP family and Cdc42 or phosphatidylinositol 4,5-biphosphate are required for their activation allowing exposure of the verprolin homology, cofilin homology, and acidic (VCA) 1The abbreviations used are: VCA, verprolin-homology, cofilin-homology, acidic domain; PDGF, platelet-derived growth factor; WAVE3, WASP family verprolin-homologous protein 3; RNAi, RNA interference; WASP, Wiscott-Aldrich syndrome; N-WASP, neural WASP; Arp2/3, actin-related proteins; BD, basic domain; AD, activating domain; co-IP, co-immunoprecipitation; GST, glutathione S-transferase; GFP, green fluorescent protein; EGFP, enhanced GFP; PI3K, phosphatidylinositol 3-kinase; siRNA, small interference RNA; DMEM, Dulbecco's modified Eagle's medium; PBS, phosphate-buffered saline. region, which can then bind to the Arp2/3 complex and initiate actin polymerization (10Higgs H.N. Pollard T.D. J. Cell Biol. 2000; 150: 1311-1320Crossref PubMed Scopus (419) Google Scholar, 11Rohatgi R. Ho H.Y. Kirschner M.W. J. Cell Biol. 2000; 150: 1299-1310Crossref PubMed Scopus (499) Google Scholar). In contrast, members of the WAVE family function downstream of Rac to induce actin polymerization (12Eden S. Rohatgi R. Podtelejnikov A.V. Mann M. Kirschner M.W. Nature. 2002; 418: 790-793Crossref PubMed Scopus (651) Google Scholar, 13Miki H. Yamaguchi H. Suetsugu S. Takenawa T. Nature. 2000; 408: 732-735Crossref PubMed Scopus (460) Google Scholar). The downstream cellular effects of WASPs and WAVEs are thought to lead to the formation of actin-containing structures known as filopodia and lamellipodia, respectively (7Takenawa T. Miki H. J. Cell Sci. 2001; 114: 1801-1809Crossref PubMed Google Scholar). WASP and WAVE proteins differ in both the signaling inputs that they receive, as well as in their mode of regulation. WASP proteins are autoinhibited by intramolecular interactions that mask the VCA domain in the absence of signaling molecules such as Cdc42 and phosphatidylinositol 4,5-biphosphate (14Kim A.S. Kakalis L.T. Abdul-Manan N. Liu G.A. Nature. 2000; PubMed Scopus Google Scholar, M.E. J.A. Cell Biol. 2003; PubMed Scopus Google Scholar). the and proteins are in an through the formation of a complex with proteins, and (12Eden S. Rohatgi R. Podtelejnikov A.V. Mann M. Kirschner M.W. Nature. 2002; 418: 790-793Crossref PubMed Scopus (651) Google Scholar, A. Ho H.Y. J. H. Kirschner M.W. Proc. Natl. Acad. Sci. U. S. A. 2004; PubMed Scopus Google Scholar, M. A. A. A. Cell Biol. 2004; PubMed Scopus Google Scholar). in the of complex, which to actin WAVE3 is in the or is proteins have been to regulate the of the WASP and WAVE proteins (7Takenawa T. Miki H. J. Cell Sci. 2001; 114: 1801-1809Crossref PubMed Google Scholar). which a to a region that is in WASP and WAVE proteins H. Suetsugu S. Takenawa T. J. 1998; PubMed Scopus Google Scholar), was to a critical role in the of of actin polymerization N. S. T. R. Y. R. Kirschner M.W. R. J. 2003; PubMed Scopus Google Scholar). the the an was found to activate N-WASP of Cdc42 or phosphatidylinositol by to the region of N-WASP M. Suetsugu S. Miki H. K. T. Takenawa T. J. Cell Biol. 2001; PubMed Scopus Google Scholar). proteins such as and have been to interact with the WASP protein through to induce actin polymerization N. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, A. Cell. Biol. PubMed Scopus Google Scholar, J. Biol. Cell. 1999; PubMed Scopus Google Scholar). the of WASP proteins is well the of the WAVE proteins, and WAVE3 in not been well elucidated. The WAVE protein is which been to be an between Rac and in the of H. Yamaguchi H. Suetsugu S. Takenawa T. Nature. 2000; 408: 732-735Crossref PubMed Scopus (460) Google Scholar). In to the of WAVE3 in actin polymerization and cytoskeleton L.M. Mullins R.D. Higgs H.N. Kaiser D.A. Blanchoin L. May R.C. Hall M.E. Pollard T.D. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 3739-3744Crossref PubMed Scopus (616) Google Scholar, A. Miki H. Yamaguchi H. Suetsugu S. M. A. K. H. K. Ochs H.D. Machesky L.M. H. Takenawa T. 2004; PubMed Scopus Google Scholar), we have that WAVE3 may also be with the of Cowell J.K. Full Text PDF PubMed Scopus Google Scholar, K. Cowell J.K. 2002; PubMed Scopus Google Scholar). Platelet-derived growth factor (PDGF) a of cellular including migration, and cell in cell via its 2003; PubMed Scopus Google Scholar, K. H. 2003; PubMed Scopus Google Scholar). PDGF been to and cell motility through activation of PI3K and the of phosphatidylinositol which in the formation of lamellipodia N. S. T. R. Y. R. Kirschner M.W. R. J. 2003; PubMed Scopus Google Scholar, S. S. Takenawa T. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, T. Yamaguchi H. T. M. T. Suetsugu S. Takenawa T. Cell Biol. 2004; PubMed Scopus Google Scholar, K. K. Suetsugu S. S. Miki H. Takenawa T. T. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar), the role of PDGF in WAVE3-mediated actin reorganization and cell motility not been used the MDA-MB-231 cells to PDGF is in WAVE3-mediated actin reorganization and cell Here we show that PDGF treatment of MDA-MB-231 cells induced the formation of lamellipodia at the of migrating and the of WAVE3 in WAVE3 also been to act downstream of PI3K and is in cell migration and the formation of lamellipodia induced by PDGF. also show that WAVE3 be through interaction with p85, the regulatory of The WAVE3 and the siRNA, with of were and to the The was to the to the expression of in the cell we and were were by The used for were for the and for the for p85, for the and for the for WAVE1, and WAVE3 were as K. Head K. Nowak N. Cowell J.K. Mamm. Genome. 2003; 14: 314-322Crossref PubMed Scopus (40) Google Scholar). The used in were as and and PI3K p85 The used were and Platelet-derived growth factor (PDGF) was and the PI3K LY294002, was were Cell MDA-MB-231 cells were in Dulbecco's modified Eagle's with stimulation with PDGF, the cells were to for in and then with PDGF. The inhibitor was to the at a of with PDGF. were in and RNA was to the RNA was a and of RNA was used to with the was to the and the was used as a for for of expression a migration was in were for and of cells was to the The of PDGF was to the The were at the cells the of the were with a The cells that were to through the the of the were and with and an with a and assay was used to the of cells to a that is in cells. MDA-MB-231 in were they were by a the cell The of the were and the was by the of the were and in for in phosphate-buffered at and with The cells were then in in for with PBS, and in the in for at as well as were at the in in were with the for with PBS, and then with the for were with in The were were a the WAVE3 at the was were in with and cells were in in to were with of in as by the was with and cells were at for an and endogenous cells were in and with and a of was The cells were the and the were to and at for at were with or for by with protein for at a were then with were by and by proteins the cell were with of GST, or proteins and the were a at The the protein were with the by with protein as were then with were by and by cellular of protein were with and a by to or and were in for at with PBS, by with the at were then and in the at for and the signals were a and were the the WAVE3 and used in the an In the for the WAVE3 and the WAVE3 the VCA domain the for the was by a were the the The were or with the of or the domain were a The were used for or The and were by L. The WASP and WAVE proteins have been to in the of actin reorganization and in the formation of filopodia and lamellipodia, leading to cell migration in cell (7Takenawa T. Miki H. J. Cell Sci. 2001; 114: 1801-1809Crossref PubMed Google Scholar, S. S. Takenawa T. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, K. K. Suetsugu S. S. Miki H. Takenawa T. T. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar, H. Miki H. Takenawa T. 2002; Google Scholar, Suetsugu S. Miki H. Y. S. T. N. Takenawa T. Nature. 2003; PubMed Scopus Google Scholar). and are required for PDGF-induced lamellipodia formation and cell migration N. S. T. R. Y. R. Kirschner M.W. R. J. 2003; PubMed Scopus Google Scholar, S. S. Takenawa T. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, T. Yamaguchi H. T. M. T. Suetsugu S. Takenawa T. Cell Biol. 2004; PubMed Scopus Google Scholar). The of WAVE3 in the PDGF-induced cell migration however, not been WAVE3 is also in PDGF-induced lamellipodia formation and cell migration in MDA-MB-231 cells. WAVE3 for Cell WAVE3 plays a role in cell migration, we the WAVE3 in MDA-MB-231 cells cells show endogenous of WAVE3, and treatment in of the The expression of the and were not by the family of the we used is for Treatment with WAVE3 in a in proteins WAVE3 is to be in actin we in WAVE3 protein the formation of lamellipodia, which are for cell and migration. of cells with or with the lamellipodia induced with PDGF and The of cells with PDGF-induced lamellipodia however, to with WAVE3 and actin polymerization also been to be in cell migration, we the migration of MDA-MB-231 cells toward PDGF, treatment with the three-dimensional migration in both cells and the cells with the are toward PDGF and through the cells show a in their to toward PDGF and also the of WAVE3 cell the a the MDA-MB-231 cells can the in the cells with not a role of WAVE in cell movement. the WAVE is required for cell and PDGF and of MDA-MB-231 role of PDGF in cell migration been in cell S. Takenawa T. Int. Rev. Cytol. 2003; 229: 245-286Crossref PubMed Scopus (57) Google Scholar, K. K. Suetsugu S. S. Miki H. Takenawa T. T. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar, K. Cell PubMed Scopus Google Scholar). a between PDGF and cell migration in we the of PDGF treatment the of MDA-MB-231 cells to lamellipodia and toward PDGF. MDA-MB-231 cells were for the of cells and and of cells lamellipodia and Treatment of cells with PDGF for induced lamellipodia formation and a in of cells and the of PDGF treatment cell motility the wound-closure cells the and were to the in the the an of cell we also the of PDGF the of cells to in a three-dimensional migration an of in the of cells that were to toward PDGF, with the cells not with PDGF and PDGF is also of the migration of MDA-MB-231 in both and migration by lamellipodia formation at the leading WAVE3 with the in the with a WAVE3 that WAVE3 protein is in both the and PDGF-induced cells WAVE3 is in K. Head K. Nowak N. Cowell J.K. Mamm. Genome. 2003; 14: 314-322Crossref PubMed Scopus (40) Google Scholar, K. Cowell J.K. 2002; PubMed Scopus Google Scholar, S. Miki H. Takenawa T. Biochem. 1999; PubMed Scopus Google Scholar). we have that WAVE3 is also in and cell as well as in cell including MDA-MB-231 cells K. Cowell J.K. 2002; PubMed Scopus Google Scholar), which may for the between of WAVE3 and the treatment of MDA-MB-231 cells with PDGF the of the WAVE3 that WAVE3 was concentrated in the and the of the cells the cells and and actin the cells induced with PDGF were to lamellipodia at the leading of migrating cells in to the of WAVE3 in the and the WAVE3 was also concentrated in the lamellipodia and with the actin structures in the lamellipodia between WAVE3 and p85 May for WAVE3-mediated and Cell of the and proteins that their function is mediated through interactions (12Eden S. Rohatgi R. Podtelejnikov A.V. Mann M. Kirschner M.W. Nature. 2002; 418: 790-793Crossref PubMed Scopus (651) Google Scholar, 13Miki H. Yamaguchi H. Suetsugu S. Takenawa T. Nature. 2000; 408: 732-735Crossref PubMed Scopus (460) Google Scholar, A. Ho H.Y. J. H. Kirschner M.W. Proc. Natl. Acad. Sci. U. S. A. 2004; PubMed Scopus Google Scholar, M. A. A. A. Cell Biol. 2004; PubMed Scopus Google Scholar). the is for WAVE3 we used the yeast two-hybrid to potential for a p85, the regulatory of the PI3K, was as a potential interaction between WAVE3 and p85 was confirmed by of WAVE3 and p85 of MDA-MB-231 cells. The of both the WAVE3 and p85 proteins in the was confirmed by and the for and the for a with the of the WAVE3 was The was not to the WAVE3-p85 complex, the of the which domain of p85 the WAVE3-p85 a of of p85, to GST, were used in protein of MDA-MB-231 cells. of WAVE3 with the in the of the C-terminal domain of p85 not the or the N-terminal or These results that p85 with WAVE3 through the C-terminal SH2 of to the of or the domain were to which domain of WAVE3 was in the interaction with p85. cells were with the WAVE3 or the and were that expression of the These were used for an which in the of both the WAVE3 protein and the WAVE3 the VCA domain not These results that the VCA domain of WAVE3 is not required for the interaction with p85. The WAVE3 domain that to p85 was the assay with yeast with the and the or an interaction with the in the the yeast the domain or of WAVE3, not that WAVE3 are not for the interaction with p85. PI3K May for the of WAVE3-mediated and Cell interaction between WAVE3 and the regulatory of PI3K the of PI3K in the of WAVE3-mediated cell migration and lamellipodia PI3K is in PDGF-induced lamellipodia formation and cell migration in MDA-MB-231 as been in a of cell (1Mitchison T.J. Cramer L.P. Cell. 1996; 84: 371-379Abstract Full Text Full Text PDF PubMed Scopus (1310) Google Scholar, T. Yamaguchi H. T. M. T. Suetsugu S. Takenawa T. Cell Biol. 2004; PubMed Scopus Google Scholar, L.M. R. N. Y. Acad. Sci. PubMed Scopus Google Scholar, M. H. Miki H. Takenawa T. S. J. Cell Sci. 2003; PubMed Scopus Google Scholar, K. Sci. 2001; Scholar, R. S. S. K. S. T. Y. Cell. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar, Cell Biol. 2002; 14: PubMed Scopus (212) Google Scholar), MDA-MB-231 cells were with the PI3K inhibitor of the cells were to lamellipodia and treatment of the cells with PDGF for in the formation of lamellipodia in of cells and of to cells at the of with PDGF, the formation of lamellipodia in of cells and PDGF treatment is a in the of cells to through the and treatment with cell migration to with the cells These results show that of PI3K with the PDGF-induced lamellipodia formation and cell migration. we have also that WAVE3 is required for lamellipodia formation and cell migration results also an role for PI3K in WAVE3-mediated lamellipodia formation and cell migration by WAVE3 to the of cells. the results that WAVE3 is for PDGF-induced lamellipodia formation and migration of MDA-MB-231 that PI3K is required for WAVE3-mediated and that a interaction between WAVE3 and p85 may be required for WAVE3 activity. The of a cell to is a critical for both cellular as well as for (1Mitchison T.J. Cramer L.P. Cell. 1996; 84: 371-379Abstract Full Text Full Text PDF PubMed Scopus (1310) Google Scholar, D.A. Cell. 1996; 84: Full Text Full Text PDF PubMed Scopus Google Scholar, T. K. Cell Biol. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). WAVE3 is a member of the WASP/WAVE family of proteins, which cellular motility through the Rac and Cdc42 (12Eden S. Rohatgi R. Podtelejnikov A.V. Mann M. Kirschner M.W. Nature. 2002; 418: 790-793Crossref PubMed Scopus (651) Google Scholar, 13Miki H. Yamaguchi H. Suetsugu S. Takenawa T. Nature. 2000; 408: 732-735Crossref PubMed Scopus (460) Google Scholar, M. A. A. A. Cell Biol. 2004; PubMed Scopus Google Scholar, H. T. Takai Y. Takenawa T. Nature. 1998; PubMed Scopus Google Scholar, R. L. Miki H. M. T. Takenawa T. Kirschner M.W. Cell. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). 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J. 2003; PubMed Scopus Google Scholar, S. S. Takenawa T. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, T. Yamaguchi H. T. M. T. Suetsugu S. Takenawa T. Cell Biol. 2004; PubMed Scopus Google Scholar). we WAVE3 a role in the formation of lamellipodia and cell migration in MDA-MB-231 cells in response to PDGF. a toward the of WAVE3 in actin reorganization that to cell we WAVE3 is with actin structures in the leading of migrating MDA-MB-231 cells. WAVE3 protein was in MDA-MB-231 cells of PDGF Treatment of cells with PDGF, however, an in the of cells with lamellipodia at the of migrating which is with the the of both PDGF as well as growth cells S. Takenawa T. Int. Rev. Cytol. 2003; 229: 245-286Crossref PubMed Scopus (57) Google Scholar, K. K. Suetsugu S. S. Miki H. Takenawa T. T. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar, K. Cell PubMed Scopus Google Scholar). PDGF treatment also in the of WAVE3 at cell lamellipodia were suggesting a role of WAVE3 in the formation of Knockdown of WAVE3 expression not abrogated the formation of lamellipodia, also MDA-MB-231 migration, which that WAVE3 expression is for both the formation of lamellipodia as well as cell migration. and are in MDA-MB-231 cells and both and were found to be in cell motility and actin in response to PDGF N. S. T. R. Y. R. Kirschner M.W. R. J. 2003; PubMed Scopus Google Scholar, S. S. Takenawa T. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, T. Yamaguchi H. T. M. T. Suetsugu S. Takenawa T. Cell Biol. 2004; PubMed Scopus Google Scholar, A. 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Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). is also that the of phosphatidylinositol as a of PI3K is for WAVE3-mediated filopodia formation and cell migration, as been for T. Yamaguchi H. T. M. T. Suetsugu S. Takenawa T. Cell Biol. 2004; PubMed Scopus Google Scholar, K. K. Suetsugu S. S. Miki H. Takenawa T. T. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). These results the the of PI3K in the formation of lamellipodia and cell migration in cell in response to growth S. Takenawa T. Int. Rev. Cytol. 2003; 229: 245-286Crossref PubMed Scopus (57) Google Scholar, N. S. T. R. Y. R. Kirschner M.W. R. J. 2003; PubMed Scopus Google Scholar, S. S. Takenawa T. Cell. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, K. K. Suetsugu S. S. Miki H. Takenawa T. T. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). PI3K is a of a and an regulatory PI3K the of phosphatidylinositol a in response to a of growth PI3K is to the cell in the cytoskeleton K. Sci. 2001; Scholar). the downstream of PI3K are not been that the of the PI3K complex to activated platelet-derived growth factor via the p85 SH2 to the of the complex cellular is R. R. L. S. Cell Biol. PubMed Scopus Google Scholar). have a interaction between the N-terminal region of WAVE3 and the C-terminal SH2 domain of p85. SH2 are known to interact with they are WAVE proteins have been to in response to PDGF H. M. Takenawa T. J. Biol. Chem. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). we found that treatment of MDA-MB-231 cells with PDGF in WAVE3 at are in the N-terminal region of WAVE3 that with the of WAVE3 a potential for at is in WAVE proteins, and a in is the to by Y. J. K. S. M. K. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), findings WAVE3 is in the interaction between WAVE3 and p85. suggest of the interaction between p85 and WAVE3 that is the interaction may regulate actin by a between Rac and WAVE3, with the activation of the Arp2/3 complex and the reorganization of the The of PI3K phosphatidylinositol was to be required for the of Rac M. Y. A. A. N. M. Y. S. S. H. Y. R. Nature. 2002; PubMed Scopus Google Scholar). The activation of Rac is also mediated by a interaction A. R. S. L. T. M. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar, H. Y. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). have found that p85 to WAVE3 through the C-terminal SH2 is as by the interaction in the yeast two-hybrid and both in and in as by the WAVE3 and p85 also to of actin polymerization in the cell These results suggest that p85 may be an between Rac and WAVE3 in the of the in the signals Rac to and proteins H. Yamaguchi H. Suetsugu S. Takenawa T. Nature. 2000; 408: 732-735Crossref PubMed Scopus (460) Google Scholar). the interaction between WAVE3 and p85 may a role in the of interaction between p85 and been to be for Rac which to actin reorganization M. J. Cell Biol. 2003; PubMed Scopus Google Scholar). a in a complex, was to regulate and actin polymerization and reorganization (12Eden S. Rohatgi R. Podtelejnikov A.V. Mann M. Kirschner M.W. Nature. 2002; 418: 790-793Crossref PubMed Scopus (651) Google Scholar, A. Ho H.Y. J. H. Kirschner M.W. Proc. Natl. Acad. Sci. U. S. A. 2004; PubMed Scopus Google Scholar, M. A. A. A. Cell Biol. 2004; PubMed Scopus Google Scholar). The that WAVE3 and p85 interact also that p85, in with an complex that may as well as proteins, may regulate the of WAVE3 by in an extracellular are is however, that both of are of the regulatory for the for with the and for