Identification of a novel Krüppel-associated box domain protein, Krim-1, that interacts with c-Myc and inhibits its oncogenic activity.
We have used the Ras recruitment system to screen for proteins that interact with the N-terminally located transactivation domain of c-Myc. The Ras recruitment system is based on the activation of the mitogenic RAS signaling pathway in yeast by the mammalian GTPase Ha-Ras. This screen led to the identification of two novel nuclear proteins termed Krim-1A and Krim-1B that both contain an N-terminal KRAB box domain and 12 or 9 Krüppel C2H2 type zinc fingers at the C terminus, respectively. We found that sequences covering the Myc box II homology region are essential for the interaction with the Krim-1 proteins and that the second N-terminal zinc finger of Krim-1 is essential for Myc binding. Both Krim-1A and -B genes appear to be expressed ubiquitously with highest levels in spleen and lymph nodes. In particular, Krim-1B and, to a lesser extent, Krim-1A are able to decrease E-box-dependent transcriptional transactivation by c-Myc-Max complexes and also the ability of Myc to malignantly transform primary rat embryo fibroblasts, which is consistent with the functional repressive properties of their KRAB domains. The transcriptional corepressor Tif-1beta is a binding partner for Krim-1 and stabilizes the protein. Our findings suggest that Myc-mediated functions can be negatively regulated by Krim-1, potentially in a complex with Tif-1beta.
Hennemann
Hanjo
H
Institut für Zellbiologie (Tumorforschung), Universitätsklinikum Essen, Virchowstrasse 173, D-45122 Essen, Germany.
Vassen
Lothar
L
Geisen
Christoph
C
Eilers
Martin
M
Möröy
Tarik
T
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002467:Cell Nucleus / Q000737:chemistry; D002471:Cell Transformation, Neoplastic; D003593:Cytoplasm / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D017353:Gene Deletion; D015870:Gene Expression / Q000187:drug effects; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D008198:Lymph Nodes / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D016133:Polymerase Chain Reaction; D016271:Proto-Oncogene Proteins c-myc / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013154:Spleen / Q000737:chemistry; D013329:Structure-Activity Relationship; D014157:Transcription Factors; D014162:Transfection; D000076183:Tripartite Motif-Containing Protein 28; D016335:Zinc Fingers
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; C486785:ZNF472 protein, human; C477007:Zfp472 protein, rat; D049452:Green Fluorescent Proteins; C101116:TRIM28 protein, human; C103190:Trim28 protein, mouse; C486304:Trim28 protein, rat; D000076183:Tripartite Motif-Containing Protein 28; C486788:Zfp472 protein, mouse