ERK phosphorylation potentiates Elk-1-mediated ternary complex formation and transactivation.
Induction of the human c-fos proto-oncogene by mitogens depends on the formation of a ternary complex by p62TCF with the serum response factor (SRF) and the serum response element (SRE). We demonstrate that Elk-1, a protein closely related to p62TCF in function, is a nuclear target of two members of the MAP kinase family, ERK1 and ERK2. Phosphorylation of Elk-1 increases the yield of ternary complex in vitro. At least five residues in the C-terminal domain of Elk-1 are phosphorylated upon growth factor stimulation of NIH3T3 cells. These residues are also phosphorylated by purified ERK1 in vitro, as determined by a combination of phosphopeptide sequencing and 2-D peptide mapping. Conversion of two of these phospho-acceptor sites to alanine impairs the formation of ternary complexes by the resulting Elk-1 proteins. Removal of these serine residues also drastically diminishes activation of the c-fos promoter in epidermal growth factor-treated cells. Analogous mutations at other sites impair activation to a lesser extent without affecting ternary complex formation in vitro. Our results indicate that phosphorylation regulates ternary complex formation by Elk-1, which is a prerequisite for the manifestation of its transactivation potential at the c-fos SRE.
Gille
H
H
Max-Planck-Institut für Immunbiologie, Spemann Laboratories, Freiburg, Germany.
Kortenjann
M
M
Thomae
O
O
Moomaw
C
C
Slaughter
C
C
Cobb
M H
MH
Shaw
P E
PE
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D016762:Genes, fos / Q000235:genetics; D006801:Humans; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D016716:PC12 Cells; D010449:Peptide Mapping; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017421:Sequence Analysis; D014157:Transcription Factors; D015533:Transcriptional Activation / Q000502:physiology*; D050807:ets-Domain Protein Elk-1
D004268:DNA-Binding Proteins; C494112:ELK1 protein, human; C494113:Elk1 protein, mouse; C494114:Elk1 protein, rat; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D004247:DNA; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases