Extracellular signal-regulated kinase binds to TFII-I and regulates its activation of the c-fos promoter.
We have previously shown that TFII-I enhances transcriptional activation of the c-fos promoter through interactions with upstream elements in a signal-dependent manner. Here we demonstrate that activated Ras and RhoA synergize with TFII-I for c-fos promoter activation, whereas dominant-negative Ras and RhoA inhibit these effects of TFII-I. The Mek1 inhibitor, PD98059 abrogates the enhancement of the c-fos promoter by TFII-I, indicating that TFII-I function is dependent on an active mitogen-activated protein (MAP) kinase pathway. Analysis of the TFII-I protein sequence revealed that TFII-I contains a consensus MAP kinase interaction domain (D box). Consistent with this, we have found that TFII-I forms an in vivo complex with extracellular signal-related kinase (ERK). Point mutations within the consensus MAP kinase binding motif of TFII-I inhibit its ability to bind ERK and its ability to enhance the c-fos promoter. Therefore, the D box of TFII-I is required for its activity on the c-fos promoter. Moreover, the interaction between TFII-I and ERK can be regulated. Serum stimulation enhances complex formation between TFII-I and ERK, and dominant-negative Ras abrogates this interaction. In addition, TFII-I can be phosphorylated in vitro by ERK and mutation of consensus MAP kinase substrate sites at serines 627 and 633 impairs the phosphorylation of TFII-I by ERK and its activity on the c-fos promoter. These results suggest that ERK regulates the activity of TFII-I by direct phosphorylation.
Kim
D W
DW
Department of Cellular and Molecular Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Cochran
B H
BH
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D016762:Genes, fos; D006801:Humans; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D017931:DNA Primers; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins; D020741:rho GTP-Binding Proteins