C-terminal SH3 domain of CrkII regulates the assembly and function of the DOCK180/ELMO Rac-GEF.

Akakura, Shin; Kar, Bishnupriya; Singh, Sukhwinder; Cho, Leong; Tibrewal, Nitu; Sanokawa-Akakura, Reiko; Reichman, Charles; Ravichandran, Kodimangalam S; Birge, Raymond B

Akakura, Shin; Kar, Bishnupriya; Singh, Sukhwinder; Cho, Leong; Tibrewal, Nitu; Sanokawa-Akakura, Reiko; Reichman, Charles; Ravichandran, Kodimangalam S; Birge, Raymond B.

Afiliación

Akakura S; Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School, Newark, New Jersey, USA.

J Cell Physiol ; 204(1): 344-51, 2005 Jul.

Article en En | MEDLINE | ID: mdl-15700267

RESUMEN

Genetic studies in Caenorhabditis elegans identified an evolutionarily conserved CED-2 (CrkII), CED-5 (DOCK180), CED-12 (ELMO), CED-10 (Rac1) module important for cell migration and phagocytosis of apoptotic cells. Previous studies have shown that DOCK180 and ELMO comprise an unconventional bipartite Dbl homology domain-independent Rac guanine nucleotide exchange factor (Rac-GEF); but it is still unclear how CrkII functions in Rac-GEF activity. In this study, we have characterized a unique function of CrkII in phagocytosis and Rac activation mediated by the C-terminal SH3 domain, a region of CrkII that has no clear cellular or biochemical function. We found that mutations that disrupt the C-terminal SH3 domain of CrkII (CrkII-SH3-C) abrogate engulfment of apoptotic cells and impair cell spreading on extracellular matrix. Surprisingly, despite the effects on engulfment, W276K CrkII strongly potentiated Rac-GTP loading when ectopically expressed in HEK 293T cells. Contrary to the effects of the true dominant negative SH2 domain mutants (R38K CrkII) and SH3-N domain mutants (W170K CrkII) that prevent macromolecular assembly of signaling proteins, W276K CrkII increases association between DOCK180 and CrkII as well as constitutive tethering of the Crk/DOCK180/ELMO protein complex that interacted with RhoG. Our results indicate that while N-terminal SH3 of CrkII promotes assembly between CrkII and DOCK180, the C-terminal SH3 of CrkII regulates the stability and turnover of the DOCK180/ELMO complex. Studies with W276K CrkII may offer a unique opportunity to study the structure and function of the DOCK180/ELMO Rac-GEF.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/metabolismo; Proteínas Proto-Oncogénicas/genética; Proteínas Proto-Oncogénicas/metabolismo; Proteínas de Unión al GTP rac/metabolismo; Dominios Homologos src/fisiología; Animales; Células COS; Chlorocebus aethiops; Proteínas de Unión al ADN; Humanos; Riñón/citología; Ratones; Mutagénesis; Células 3T3 NIH; Estructura Terciaria de Proteína; Proteínas Proto-Oncogénicas/química; Proteínas Proto-Oncogénicas c-crk; Relación Estructura-Actividad; Factores de Transcripción/metabolismo; Proteína de Unión al GTP rac1/metabolismo; Dominios Homologos src/genética

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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Proteínas Proto-Oncogénicas / Dominios Homologos src / Proteínas de Unión al GTP rac / Proteínas Adaptadoras Transductoras de Señales Tipo de estudio: Prognostic_studies Límite: Animals / Humans Idioma: En Revista: J Cell Physiol Año: 2005 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Estados Unidos

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