Phosphorylation of Ets1 regulates the complementation of a CSF-1 receptor impaired in mitogenesis.
Ets1, the founder member of the Ets transcription factor family, is involved in a variety of developmental and cellular processes. Previous studies have shown that serine phosphorylation of Ets1 inhibits its DNA binding activity, suggesting that phosphorylation is important in the regulation of Ets1 function. To further examine Ets1 phosphorylation, we ectopically expressed Ets1 in fibroblasts and stimulated these cells with serum. Using two-dimensional tryptic phosphopeptide analysis and site-directed mutagenesis, we found that Ets1 was phosphorylated on threonine 38, a residue conserved in several Ets proteins. Substitution of this residue with alanine enhanced CSF-1-dependent colony formation in semi-solid medium of NIH3T3 cells expressing a mitogenically defective CSF-1 receptor [Y809F]. Threonine 38 is part of a consensus amino-acid sequence frequently recognized and targeted by members of the MAP kinase family. Moreover, this residue is phosphorylated in vitro by recombinant ERK2, which suggests that the kinase which phosphorylates threonine 38 in vivo is a member of the MAP kinase family. In addition, phosphorylation on threonine 38 seems to negatively regulate Ets1 activity in response to growth-factor stimulation.
Rabault
B
B
Laboratoire d'Oncologie Virale et Cellulaire, CNRS UMR 146, Institut Curie, Centre Universitaire, Orsay, France.
Roussel
M F
MF
Quang
C T
CT
Ghysdael
J
J
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D005816:Genetic Complementation Test; D051379:Mice; D008938:Mitosis / Q000235:genetics*; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010766:Phosphorylation; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics* / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; C494042:Ets1 protein, mouse; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D014157:Transcription Factors; D016186:Receptor, Macrophage Colony-Stimulating Factor