DA-Raf1, a competent intrinsic dominant-negative antagonist of the Ras-ERK pathway, is required for myogenic differentiation.
Ras activates Raf, leading to the extracellular-regulated kinase (ERK)-mitogen-activated protein kinase pathway, which is involved in a variety of cellular, physiological, and pathological responses. Thus, regulators of this Ras-Raf interaction play crucial roles in these responses. In this study, we report a novel regulator of the Ras-Raf interaction named DA-Raf1. DA-Raf1 is a splicing isoform of A-Raf with a wider tissue distribution than A-Raf. It contains the Ras-binding domain but lacks the kinase domain, which is responsible for activation of the ERK pathway. As inferred from its structure, DA-Raf1 bound to activated Ras as well as M-Ras and interfered with the ERK pathway. The Ras-ERK pathway is essential for the negative regulation of myogenic differentiation induced by growth factors. DA-Raf1 served as a positive regulator of myogenic differentiation by inducing cell cycle arrest, the expression of myogenin and other muscle-specific proteins, and myotube formation. These results imply that DA-Raf1 is the first identified competent, intrinsic, dominant-negative antagonist of the Ras-ERK pathway.
Yokoyama
Takashi
T
Department of Biology, Graduate School of Science, Chiba University, Chiba 263-8522, Japan.
Takano
Kazunori
K
Yoshida
Akira
A
Katada
Fumiko
F
Sun
Peng
P
Takenawa
Tadaomi
T
Andoh
Toshiwo
T
Endo
Takeshi
T
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D002454:Cell Differentiation; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D024510:Muscle Development / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000201:enzymology*; D018008:Myogenin / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D048491:Proto-Oncogene Proteins A-raf / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D018631:ras Proteins
D018008:Myogenin; D020033:Protein Isoforms; C521643:DA-Raf1 protein, mouse; D048491:Proto-Oncogene Proteins A-raf; D048049:Extracellular Signal-Regulated MAP Kinases; C109418:Mras protein, mouse; D020559:Monomeric GTP-Binding Proteins; D018631:ras Proteins