Identification of beta-catenin as a target of the intracellular tyrosine kinase PTK6.
J Cell Sci
; 123(Pt 2): 236-45, 2010 Jan 15.
Article
em En
| MEDLINE
| ID: mdl-20026641
ABSTRACT
Disruption of the gene encoding protein tyrosine kinase 6 (PTK6) leads to increased growth, impaired enterocyte differentiation and higher levels of nuclear beta-catenin in the mouse small intestine. Here, we demonstrate that PTK6 associates with nuclear and cytoplasmic beta-catenin and inhibits beta-catenin- and T-cell factor (TCF)-mediated transcription. PTK6 directly phosphorylates beta-catenin on Tyr64, Tyr142, Tyr331 and/or Tyr333, with the predominant site being Tyr64. However, mutation of these sites does not abrogate the ability of PTK6 to inhibit beta-catenin transcriptional activity. Outcomes of PTK6-mediated regulation appear to be dependent on its intracellular localization. In the SW620 colorectal adenocarcinoma cell line, nuclear-targeted PTK6 negatively regulates endogenous beta-catenin/TCF transcriptional activity, whereas membrane-targeted PTK6 enhances beta-catenin/TCF regulated transcription. Levels of TCF4 and the transcriptional co-repressor TLE/Groucho increase in SW620 cells expressing nuclear-targeted PTK6. Knockdown of PTK6 in SW620 cells leads to increased beta-catenin/TCF transcriptional activity and increased expression of beta-catenin/TCF target genes Myc and Survivin. Ptk6-null BAT-GAL mice, containing a beta-catenin-activated LacZ reporter transgene, have increased levels of beta-galactosidase expression in the gastrointestinal tract. The ability of PTK6 to negatively regulate beta-catenin/TCF transcription by modulating levels of TCF4 and TLE/Groucho could contribute to its growth-inhibitory activities in vivo.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Tirosina Quinases
/
Quinases da Família src
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Espaço Intracelular
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Beta Catenina
/
Proteínas de Neoplasias
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Cell Sci
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Estados Unidos