Phosphorylation of WASp is a key regulator of activity and stability in vivo.
The Wiskott-Aldrich syndrome protein (WASp) is a key cytoskeletal regulator in hematopoietic cells. Covalent modification of a conserved tyrosine by phosphorylation has emerged as an important potential determinant of activity, although the physiological significance remains uncertain. In a murine knockin model, mutation resulting in inability to phosphorylate Y293 (Y293F) mimicked many features of complete WASp-deficiency. Although a phosphomimicking mutant Y293E conferred enhanced actin-polymerization, the cellular phenotype was similar due to functional dysregulation. Furthermore, steady-state levels of Y293E-WASp were markedly reduced compared to wild-type WASp and Y293F-WASp, although partially recoverable by treatment of cells with proteasome inhibitors. Consequently, tyrosine phosphorylation plays a critical role in normal activation of WASp in vivo, and is indispensible for multiple tasks including proliferation, phagocytosis, chemotaxis, and assembly of adhesion structures. Furthermore, it may target WASp for proteasome-mediated degradation, thereby providing a default mechanism for self-limiting stimulation of the Arp2/3 complex.
Blundell
Michael P
MP
Molecular Immunology Unit, Wolfson Centre for Gene Therapy of Childhood Disease and Centre for Immunodeficiency, UCL Institute of Child Health, London, WC1N 1EH, United Kingdom.
Bouma
Gerben
G
Metelo
Joao
J
Worth
Austen
A
Calle
Yolanda
Y
Cowell
Lucy A
LA
Westerberg
Lisa S
LS
Moulding
Dale A
DA
Mirando
Samuel
S
Kinnon
Christine
C
Cory
Giles O
GO
Jones
Gareth E
GE
Snapper
Scott B
SB
Burns
Siobhan O
SO
Thrasher
Adrian J
AJ
D000199:Actins / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D002460:Cell Line; D002465:Cell Movement; D002522:Chlorocebus aethiops; D006410:Hematopoiesis; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016297:Mutagenesis, Site-Directed; D010587:Phagocytosis; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry; D014923:Wiskott-Aldrich Syndrome / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051316:Wiskott-Aldrich Syndrome Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D011994:Recombinant Proteins; C495768:Was protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein; D014443:Tyrosine