Transactivation of gene expression by Myc is inhibited by mutation at the phosphorylation sites Thr-58 and Ser-62.
The product of the human c-myc protooncogene (Myc) is a sequence-specific DNA binding protein. Here, we demonstrate that the placement of the specific Myc DNA binding site CACGTG upstream of a luciferase reporter gene conferred Myc-stimulated expression that was inhibited by the overexpression of the basic-helix-loop-helix/leucine zipper protein Max. It was observed that Myc was phosphorylated in vivo within the NH2-terminal domain at Thr-58 and Ser-62. Replacement of these phosphorylation sites with Ala residues caused a marked decrease in Myc-stimulated reporter gene expression. In contrast, the replacement of Thr-58 or Ser-62 with an acidic residue (Glu) caused only a small inhibition of transactivation. Together, these data demonstrate that the NH2-terminal phosphorylation sites Thr-58 and Ser-62 are required for high levels of transactivation of gene expression by Myc.
Gupta
S
S
Program in Molecular Medicine, University of Massachusetts Medical School, Worcester 01605.
Seth
A
A
Davis
R J
RJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D002522:Chlorocebus aethiops; D003062:Codon; D004247:DNA / Q000235:genetics; D015870:Gene Expression; D016259:Genes, myc; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D010766:Phosphorylation; D010957:Plasmids; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D011494:Protein Kinases / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D012694:Serine; D013379:Substrate Specificity; D013912:Threonine; D015533:Transcriptional Activation
D003062:Codon; D009838:Oligodeoxyribonucleotides; D016271:Proto-Oncogene Proteins c-myc; D013912:Threonine; D012694:Serine; D004247:DNA; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases