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© The Rockefeller University Press,
0021-9525/2001//181 $5.00
The Journal of Cell Biology, Volume 152, Number 1,
, 2001 181-196
Original Article |
Cbl Associates with Pyk2 and Src to Regulate Src Kinase Activity, 
vβ3 Integrin-Mediated Signaling, Cell Adhesion, and Osteoclast Motility
roland.baron{at}yale.edu
The signaling events downstream of integrins that regulate cell attachment and motility are only partially understood. Using osteoclasts and transfected 293 cells, we find that a molecular complex comprising Src, Pyk2, and Cbl functions to regulate cell adhesion and motility. The activation of integrin
vβ3 induces the [Ca2+]i-dependent phosphorylation of Pyk2 Y402, its association with Src SH2, Src activation, and the Src SH3-dependent recruitment and phosphorylation of c-Cbl. Furthermore, the PTB domain of Cbl is shown to bind to phosphorylated Tyr-416 in the activation loop of Src, the autophosphorylation site of Src, inhibiting Src kinase activity and integrin-mediated adhesion. Finally, we show that deletion of c Src or c-Cbl leads to a decrease in osteoclast migration. Thus, binding of vβ3 integrin induces the formation of a Pyk2/Src/Cbl complex in which Cbl is a key regulator of Src kinase activity and of cell adhesion and migration. These findings may explain the osteopetrotic phenotype in the Src–/– mice.
Key Words: Cbl • Src • Pyk2 • osteoclast • vitronectin receptor (vβ3)
© 2001 The Rockefeller University Press
Drs. Sanjay and Houghton contributed equally to this work and should be considered co-first authors.Abbreviations used in this paper: ECM, extracellular matrix; IP, immunoprecipitate; mRIPA, modified radioimmune precipitation assay; OCL, osteoclast-like cell; VnR, vitronectin receptor.
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