TY  - JOUR
A1  - Eisenhardt, Anja E.
A1  - Sprenger, Adrian
A1  - Röring, Michael
A1  - Herr, Ricarda
A1  - Weinberg, Florian
A1  - Köhler, Martin
A1  - Braun, Sandra
A1  - Orth, Joachim
A1  - Diedrich, Britta
A1  - Lanner, Ulrike
A1  - Tscherwinski, Natalja
A1  - Schuster, Simon
A1  - Dumaz, Nicolas
A1  - Schmidt, Enrico
A1  - Baumeister, Ralf
A1  - Schlosser, Andreas
A1  - Dengjel, Jörn
A1  - Brummer, Tilman
T1  - Phospho-proteomic analyses of B-Raf protein complexes reveal new regulatory principles
JF  - Oncotarget
N2  - B-Raf represents a critical physiological regulator of the Ras/RAF/MEK/ERK-pathway and a pharmacological target of growing clinical relevance, in particular in oncology. To understand how B-Raf itself is regulated, we combined mass spectrometry with genetic approaches to map its interactome in MCF-10A cells as well as in B-Raf deficient murine embryonic fibroblasts (MEFs) and B-Raf/Raf-1 double deficient DT40 lymphoma cells complemented with wildtype or mutant B-Raf expression vectors. Using a multi-protease digestion approach, we identified a novel ubiquitination site and provide a detailed B-Raf phospho-map. Importantly, we identify two evolutionary conserved phosphorylation clusters around T401 and S419 in the B-Raf hinge region. SILAC labelling and genetic/biochemical follow-up revealed that these clusters are phosphorylated in the contexts of oncogenic Ras, sorafenib induced Raf dimerization and in the background of the V600E mutation. We further show that the vemurafenib sensitive phosphorylation of the T401 cluster occurs in trans within a Raf dimer. Substitution of the Ser/Thr-residues of this cluster by alanine residues enhances the transforming potential of B-Raf, indicating that these phosphorylation sites suppress its signaling output. Moreover, several B-Raf phosphorylation sites, including T401 and S419, are somatically mutated in tumors, further illustrating the importance of phosphorylation for the regulation of this kinase.
KW  - BRAF
KW  - proteomics
KW  - phosphorylation
KW  - sorafenib
KW  - protein-protein interaction
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166529
VL  - 7
IS  - 18
ER  -