Regulation of Egr-1-dependent gene expression by the C-terminal activation domain.
The present study analyzes the role of the C-terminal activation domain for Egr-1 transcriptional activity using N-terminal deletion mutants. Mutant N372 comprising the entire C-terminal activation domain and partly truncated DNA-binding and nuclear translocation domains functioned as the transdominant repressor of Egr-1-dependent gene transcription. Activity of the SV40 promoter, however, was not affected by the N372 mutant. Analysis of additional Egr-1 mutants revealed that the transdominant negative effect of N372 was dependent on truncation of the zinc finger motifs that mediate DNA binding. Reconstitution of the zinc fingers was sufficient to generate Egr-1 proteins with potent transcriptional activity. The inhibitory mutant N372 is efficiently translocated to the nucleus, but fails to bind DNA and does not displace DNA-bound wildtype Egr-1. These results provide evidence for an Egr-1-specific cofactor that interacts with the C-terminal activation domain and is essential for Egr-1 transcriptional activity.
Institute of Medical Microbiology, Immunology and Hygiene, Technische Universität, Munich, Germany.
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Gosslar
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RM
Schmid
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Holzmann
D016475:3T3 Cells; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D051766:Early Growth Response Protein 1; D005786:Gene Expression Regulation; D005799:Genes, Dominant; D006801:Humans; D017874:Immediate-Early Proteins; D007668:Kidney / Q000166:cytology; D051379:Mice; D016254:Mutagenesis, Insertional; D010446:Peptide Fragments / Q000235:genetics / Q000502:physiology*; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D017874:Immediate-Early Proteins; D010446:Peptide Fragments; D014157:Transcription Factors; D004247:DNA