Role of c-Src tyrosine kinase in G protein-coupled receptor- and Gbetagamma subunit-mediated activation of mitogen-activated protein kinases.
J Biol Chem
; 271(32): 19443-50, 1996 Aug 09.
Article
em En
| MEDLINE
| ID: mdl-8702633
ABSTRACT
Several G protein-coupled receptors that interact with pertussis toxin-sensitive heterotrimeric G proteins mediate Ras-dependent activation of mitogen-activated protein (MAP) kinases. The mechanism involves Gbetagamma subunit-mediated increases in tyrosine phosphorylation of the Shc adapter protein, Shc*Grb2 complex formation, and recruitment of Ras guanine nucleotide exchange factor activity. We have investigated the role of the ubiquitous nonreceptor tyrosine kinase c-Src in activation of the MAP kinase pathway via endogenous G protein-coupled lysophosphatidic acid (LPA) receptors or by transient expression of Gbetagamma subunits in COS-7 cells. In vitro kinase assays of Shc immunoprecipitates following LPA stimulation demonstrated rapid, transient recruitment of tyrosine kinase activity into Shc immune complexes. Recruitment of tyrosine kinase activity was pertussis toxin-sensitive and mimicked by cellular expression of Gbetagamma subunits. Immunoblots for coprecipitated proteins in Shc immunoprecipitates revealed a transient association of Shc and c-Src following LPA stimulation, which coincided with increases in Shc-associated tyrosine kinase activity and Shc tyrosine phosphorylation. LPA stimulation or expression of Gbetagamma subunits resulted in c-Src activation, as assessed by increased c-Src autophosphorylation. Overexpression of wild-type or constitutively active mutant c-Src, but not kinase inactive mutant c-Src, lead to increased tyrosine kinase activity in Shc immunoprecipitates, increased Shc tyrosine phosphorylation, and Shc.Grb2 complex formation. MAP kinase activation resulting from LPA receptor stimulation, expression of Gbetagamma subunits, or expression of c-Src was sensitive to dominant negatives of mSos, Ras, and Raf. Coexpression of Csk, which inactivates Src family kinases by phosphorylating the regulatory C-terminal tyrosine residue, inhibited LPA stimulation of Shc tyrosine phosphorylation, Shc.Grb2 complex formation, and MAP kinase activation. These data suggest that Gbetagamma subunit-mediated formation of Shc.c-Src complexes and c-Src kinase activation are early events in Ras-dependent activation of MAP kinase via pertussis toxin-sensitive G protein-coupled receptors.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Quinases
/
Proteínas Tirosina Quinases
/
Receptores de Superfície Celular
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Proteínas de Ligação ao GTP
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Receptores Acoplados a Proteínas G
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Proteínas Adaptadoras de Transdução de Sinal
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
EEUU
/
ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
/
EUA
/
UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA