Activation loop phosphorylation regulates B-Raf in vivo and transformation by B-Raf mutants.
EMBO J
; 35(2): 143-61, 2016 Jan 18.
Article
em En
| MEDLINE
| ID: mdl-26657898
ABSTRACT
Despite being mutated in cancer and RASopathies, the role of the activation segment (AS) has not been addressed for B-Raf signaling in vivo. Here, we generated a conditional knock-in mouse allowing the expression of the B-Raf(AVKA) mutant in which the AS phosphoacceptor sites T599 and S602 are replaced by alanine residues. Surprisingly, despite producing a kinase-impaired protein, the Braf(AVKA) allele does not phenocopy the lethality of Braf-knockout or paradoxically acting knock-in alleles. However, Braf(AVKA) mice display abnormalities in the hematopoietic system, a distinct facial morphology, reduced ERK pathway activity in the brain, and an abnormal gait. This phenotype suggests that maximum B-Raf activity is required for the proper development, function, and maintenance of certain cell populations. By establishing conditional murine embryonic fibroblast cultures, we further show that MEK/ERK phosphorylation and the immediate early gene response toward growth factors are impaired in the presence of B-Raf(AVKA). Importantly, alanine substitution of T599/S602 impairs the transformation potential of oncogenic non-V600E B-Raf mutants and a fusion protein, suggesting that blocking their phosphorylation could represent an alternative strategy to ATP-competitive inhibitors.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Proto-Oncogênicas B-raf
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
EMBO J
Ano de publicação:
2016
Tipo de documento:
Article