Suppression of MEK/ERK signalling by Myc: role of Bin-1.
We report for the first time that over-expression of Myc suppresses mitogen-activated ERK kinase (MEK)/extracellular regulated kinase (ERK) signalling in chick embryo fibroblasts (CEF). Myc does not interfere with individual components of the signalling cascade, since efficient signal propagation via MEK and ERK in Myc-infected CEF can be seen. However, using the Myc-binding domain (MBD) of Bin-1, which binds to and negatively regulates the activity of Myc, we selectively suppressed Myc-induced apoptosis, without affecting its transforming properties. This was accompanied by a restoration in MEK/ERK signalling, suggesting a critical role for this pathway in regulating apoptosis in these cells. This was also confirmed using a specific pharmacological inhibitor of MEK. Experiments with conditioned media suggest that over-expression of Myc may inhibit autocrine growth factor production, which can be restored by co-expression of MBD. Although the identity of the growth factor(s) is not known, we propose a feedback mechanism whereby Myc interferes with growth factor signalling.
Telfer
Joan F
JF
Biomedical Research Centre, University of Dundee, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK.
Urquhart
Jennifer
J
Crouch
Dorothy H
DH
D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D019898:Autocrine Communication; D002070:Butadienes / Q000494:pharmacology; D002467:Cell Nucleus / Q000737:chemistry; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002642:Chick Embryo; D015536:Down-Regulation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors*; D006133:Growth Substances / Q000502:physiology; D020935:MAP Kinase Signaling System; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D009570:Nitriles / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; C109221:Bin1 protein, mouse; D002070:Butadienes; D006133:Growth Substances; D009419:Nerve Tissue Proteins; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D025521:Tumor Suppressor Proteins; C113580:U 0126; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases