title: Optogenetically controlled RAF to characterize BRAF and CRAF protein kinase inhibitors.
abstract: Here, we applied optoRAF, an optogenetic tool for light-controlled clustering and activation of RAF proteins that mimics the natural occurring RAS-mediated dimerization. This versatile tool allows studying the effect on BRAF and CRAF homodimer- as well as heterodimer-induced RAF signaling. Vemurafenib and dabrafenib are two clinically approved inhibitors for BRAF that efficiently suppress the kinase activity of oncogenic BRAF (V600E). However in wild-type BRAF expressing cells, BRAF inhibitors can exert paradoxical activation of wild-type CRAF. Using optoRAF, vemurafenib was identified as paradoxical activator of BRAF and CRAF homo- and heterodimers. Dabrafenib enhanced activity of light-stimulated CRAF at low dose and inhibited CRAF signaling at high dose. Moreover, dabrafenib increased the protein level of CRAF proteins but not of BRAF proteins. Increased CRAF levels correlate with elevated RAF signaling in a dabrafenib-dependent manner, independent of light activation.
authors.affiliation: BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany.|Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
authors.forename: Claire V
authors.initials: CV
authors.lastname: Chatelle
authors.affiliation: BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany.|Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
authors.forename: Désirée
authors.initials: D
authors.lastname: Hövermann
authors.affiliation: Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Müller
authors.affiliation: BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany.|SGBM - Spemann Graduate School of Biology and Medicine, University of Freiburg, Albertstr. 19A, 79104 Freiburg, Germany.|Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
authors.forename: Hanna J
authors.initials: HJ
authors.lastname: Wagner
authors.affiliation: BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany.|SGBM - Spemann Graduate School of Biology and Medicine, University of Freiburg, Albertstr. 19A, 79104 Freiburg, Germany.|Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
authors.forename: Wilfried
authors.initials: W
authors.lastname: Weber
authors.affiliation: BIOSS - Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany.|Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Radziwill
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D004790:Enzyme Induction / Q000528:radiation effects; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D062308:Optogenetics; D010091:Oximes / Q000494:pharmacology; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D000077484:Vemurafenib
chemical_list: D000970:Antineoplastic Agents; D007093:Imidazoles; D007211:Indoles; D010091:Oximes; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D000077484:Vemurafenib; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf; C561627:dabrafenib