Effects of Raf dimerization and its inhibition on normal and disease-associated Raf signaling.
Raf kinases are essential for normal Ras-Raf-MEK-ERK pathway signaling, and activating mutations in components of this pathway are associated with a variety of human cancers, as well as the related developmental disorders Noonan, LEOPARD, and cardiofaciocutaneous syndromes. Although the Raf kinases are known to dimerize during normal and disease-associated Raf signaling, the functional significance of Raf dimerization has not been fully elucidated. Here, using mutational analysis and a peptide inhibitor, we show that dimerization is required for normal Ras-dependent Raf activation and for the biological function of disease-associated Raf mutants with moderate, low, or impaired kinase activity. However, dimerization is not needed for the function of B-Raf mutants with high catalytic activity, such as V600E-B-Raf. Importantly, we find that a dimer interface peptide can effectively block Raf dimerization and inhibit Raf signaling when dimerization is required for Raf function, thus identifying the Raf dimer interface as a therapeutic target.
Laboratory of Cell and Developmental Signaling, National Cancer Institute at Frederick, Frederick, MD 21702, USA.
Alyson K
AK
Freeman
Daniel A
DA
Ritt
Deborah K
DK
Morrison
D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System; D051379:Mice; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D009369:Neoplasms / Q000201:enzymology; D010446:Peptide Fragments / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000502:physiology; D054730:Protein Interaction Domains and Motifs; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D055503:Protein Multimerization; D048490:raf Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
D010446:Peptide Fragments; D010982:Platelet-Derived Growth Factor; D047428:Protein Kinase Inhibitors; D004815:Epidermal Growth Factor; D048490:raf Kinases; D018631:ras Proteins