Multiple regions of ETO cooperate in transcriptional repression.
In acute myeloid leukemias (AMLs) with t(8;21), the transcription factor AML1 is juxtaposed to the zinc finger nuclear protein ETO (Eight-Twenty-One), resulting in transcriptional repression of AML1 target genes. ETO has been shown to interact with corepressors, such as N-CoR and mSin3A to form complexes containing histone deacetylases. To define regions of ETO required for maximal repressor activity, we analyzed amino-terminal deletions in a transcriptional repression assay. We found that ETO mutants lacking the first 236 amino acids were not affected in their repressor activity, whereas a further deletion of 85 amino acids drastically reduced repressor function and high molecular weight complex formation. This latter mutant can still homodimerize and bind to N-CoR but shows only weak binding to mSin3A. Furthermore, we could show that a "core repressor domain" comprising nervy homology region 2 and its amino- and carboxyl-terminal flanking sequences recruits mSin3A and induces transcriptional repression. These results suggest that mSin3A and N-CoR bind to ETO independently and that both binding sites cooperate to maximize ETO-mediated transcriptional repression. Thus, ETO has a modular structure, and the interaction between the individual elements is essential for the formation of a stable repressor complex and efficient transcriptional repression.
Hildebrand
D
D
Georg-Speyer-Haus, Institute for Biomedical Research, Paul-Ehrlich Strasse 42-44, 60596 Frankfurt, Germany.
Tiefenbach
J
J
Heinzel
T
T
Grez
M
M
Maurer
A B
AB
D000596:Amino Acids / Q000737:chemistry; D002460:Cell Line; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000378:metabolism; D056971:Nuclear Receptor Co-Repressor 1; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins; D000075142:RUNX1 Translocation Partner 1 Protein; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection; D016335:Zinc Fingers
D000596:Amino Acids; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; C539127:NCOR1 protein, human; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D011518:Proto-Oncogene Proteins; D000075142:RUNX1 Translocation Partner 1 Protein; C493728:RUNX1 protein, human; C082222:RUNX1T1 protein, human; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C099683:SIN3A transcription factor; D014157:Transcription Factors; D005982:Glutathione Transferase; D056264:Sin3 Histone Deacetylase and Corepressor Complex