Erk/Src phosphorylation of cortactin acts as a switch on-switch off mechanism that controls its ability to activate N-WASP.
The Arp2/3 complex can be independently activated to initiate actin polymerization by the VCA domain of WASP family members and by the acidic N-terminal and F-actin-binding repeat region of cortactin, which possesses a C-terminal SH3 domain. Cortactin is a target for phosphorylation by Src tyrosine kinases and by serine/threonine kinases that include Erk. Here we demonstrate that cortactin binds N-WASP and WASP via its SH3 domain, induces in vitro N-WASP-mediated actin polymerization, and colocalizes with N-WASP and WASP at sites of active actin polymerization. Erk phosphorylation and a mimicking S405,418D double mutation enhanced cortactin binding and activation of N-WASP. In contrast, Src phosphorylation inhibited the ability of cortactin previously phosphorylated by Erk, and that of S405,418D double mutant cortactin, to bind and activate N-WASP. Furthermore, Y-->D mutation of three tyrosine residues targeted by Src (Y421, Y466, and Y482) inhibited the ability of S405,418D cortactin to activate N-WASP. We propose that Erk phosphorylation liberates the SH3 domain of cortactin from intramolecular interactions with proline-rich regions, causing it to synergize with WASP and N-WASP in activating the Arp2/3 complex, and that Src phosphorylation terminates cortactin activation of N-WASP and WASP.
Martinez-Quiles
Narcisa
N
Division of Immunology, Children's Hospital, Boston, MA 02115, USA.
Ho
Hsin-Yi Henry
HY
Kirschner
Marc W
MW
Ramesh
Narayanaswamy
N
Geha
Raif S
RS
D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D051356:Cortactin; D003598:Cytoskeletal Proteins / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D041701:Swiss 3T3 Cells; D051316:Wiskott-Aldrich Syndrome Protein; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D018909:src Homology Domains; D019061:src-Family Kinases / Q000378:metabolism*
C495926:ACTR2 protein, human; C495928:ACTR3 protein, human; D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins; C495927:Actr2 protein, mouse; C495929:Actr3 protein, mouse; C495868:CTTN protein, human; D051356:Cortactin; C495869:Cttn protein, mouse; D003598:Cytoskeletal Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; C495767:WAS protein, human; C495771:WASL protein, human; C495768:Was protein, mouse; C495772:Wasl protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases