EGF triggers neuronal differentiation of PC12 cells that overexpress the EGF receptor.
BACKGROUND
Mitogen-activated protein (MAP) kinase is the central component of a signal transduction pathway that is activated by growth factors interacting with receptors that have protein tyrosine kinase activity. The stimulation of PC12 phaeochromocytoma cells with nerve growth factor leads to the sustained activation and nuclear translocation of the p42 and p44 isoforms of MAP kinase and induces the differentiation of these chromaffin cells to a sympathetic-neuron-like phenotype. In contrast, stimulation with epidermal growth factor induces a transient activation of p42 and p44 MAP kinases without pronounced nuclear translocation and does not trigger cell differentiation. We have examined whether the differential activation of MAP kinases forms the basis of the differential response of the cells to the two factors.


RESULTS
By overexpressing either wild-type or mutant receptors for epidermal growth factor in PC12 cells, we found that p42 and p44 MAP kinase activity remains elevated for longer in cells that overexpress receptors than in untransfected cells. Epidermal growth factor promotes both a striking nuclear translocation of p42 MAP kinase and the differentiation of the overexpressing cells.


CONCLUSIONS
Our results strongly suggest that the distinct effects of nerve growth factor and epidermal growth factor on PC12 cell differentiation can be explained by differences in the extent and duration of activation of p42 and p44 MAP kinases in response to the two factors, without invoking a signal transduction pathway specific to nerve growth factor.
Department of Biochemistry, University of Dundee, UK.
S
S
Traverse
K
K
Seedorf
H
H
Paterson
C J
CJ
Marshall
P
P
Cohen
A
A
Ullrich
D000818:Animals; D001692:Biological Transport; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000201:enzymology; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D009414:Nerve Growth Factors / Q000494:pharmacology; D016716:PC12 Cells / Q000187:drug effects*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015398:Signal Transduction; D014162:Transfection
D009414:Nerve Growth Factors; D011993:Recombinant Fusion Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D017871:Calcium-Calmodulin-Dependent Protein Kinases