Phosphorylation of tyrosine 291 enhances the ability of WASp to stimulate actin polymerization and filopodium formation. Wiskott-Aldrich Syndrome protein.
Wiskott-Aldrich Syndrome protein (WASp) is a key regulator of the Arp2/3 complex and the actin cytoskeleton in hematopoietic cells. WASp is capable of forming an auto-inhibited conformation, which can be disrupted by binding of Cdc42 and phosphatidylinositol 4,5-bisphosphate, leading to its activation. Stimulation of the collagen receptor on platelets and crosslinking the B-cell receptor induce tyrosine phosphorylation of WASp. Here we show that the Src family kinase Hck induces phosphorylation of WASp-Tyr(291) independently of Cdc42 and that this causes a shift in the mobility of WASp upon SDS-PAGE. A phospho-mimicking mutant, WASp-Y291E, exhibited an enhanced ability to stimulate actin polymerization in a cell-free system and when microinjected into primary macrophages induced extensive filopodium formation with greater efficiency than wild-type WASp or a Y291F mutant. We propose that phosphorylation of Tyr(291) directly regulates WASp function.
Cory
Giles O C
GO
Ludwig Institute for Cancer Research, Royal Free and University College Medical School Branch, Courtauld Building, 91 Riding House Street, London W1W 7BS, United Kingdom.
Garg
Ritu
R
Cramer
Rainer
R
Ridley
Anne J
AJ
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D048429:Cell Size; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008845:Microinjections; D009154:Mutation; D010766:Phosphorylation; D011108:Polymers / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051572:Proto-Oncogene Proteins c-hck; D011554:Pseudopodia / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*; D051316:Wiskott-Aldrich Syndrome Protein; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
D000199:Actins; D011108:Polymers; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; C495767:WAS protein, human; C495768:Was protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C496631:HCK protein, human; C496632:Hck protein, mouse; D051572:Proto-Oncogene Proteins c-hck; D020764:cdc42 GTP-Binding Protein