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An essential domain of the c-myc protein interacts with a nuclear factor that is also required for E1A-mediated
D E Brough1, T J Hofmann, K B Ellwood
1Department of Molecular Biology, Princeton University, New Jersey 08544.
Abstract:
Cell transformation by nuclear oncogenes such as c-myc presumably involves the transcriptional activation of a set of target genes that participate in the control of cell division. The function of a small evolutionarily conserved domain of the c-myc gene encompassing amino acids 129 to 145 was analyzed to explore the relationship between cell transformation and transcriptional activation. Deletion of this domain inactivated the c-myc oncogene for cell transformation while retaining the ability to activate transcription of either myc consensus binding sites or a GAL4-dependent promoter when the c-myc N-terminus was fused to the GAL4 DNA-binding domain. Point mutations that altered a conserved tryptophan (amino acid 136) within this domain had similar effects. Expression of the wt c-Myc N terminus (amino acids 1 to 262) as a GAL4 fusion was a dominant inhibitor of cell transformation by the c-myc oncogene, and this same domain also inhibited transformation by the adenovirus E1A gene. Surprisingly, deletion of amino acids 129 to 145 eliminated the dominant negative activity of GAL4-Myc on both c-myc and E1A transformation. Expression of the GAL4-Myc protein in Cos cells led to the formation of a specific complex between the Myc N terminus and a nuclear factor, and this complex was absent with the dl129-145 mutant. These results suggest that an essential domain of the c-Myc protein interacts with a specific nuclear factor that is also required for E1A transformation.
Insights
A specific domain in the c-Myc protein (amino acids 129-145) is crucial for cell transformation and interacts with a nuclear factor essential for both c-Myc and adenovirus E1A oncogene activity.
Area of Science:
- Molecular Biology
- Oncology
- Virology
Background:
- Nuclear oncogenes like c-Myc drive cell transformation by activating target genes involved in cell division.
- Understanding the precise mechanisms of oncogene function is critical for cancer research.
Purpose of the Study:
- To investigate the role of a conserved domain (amino acids 129-145) within the c-Myc protein in cell transformation and transcriptional activation.
- To explore the relationship between this domain, nuclear factor interaction, and oncogenic activity.
Main Methods:
- Analyzing the effects of deleting or mutating amino acids 129-145 in the c-Myc gene on cell transformation.
- Using GAL4 fusion proteins to assess transcriptional activation and dominant inhibitory effects.
- Investigating protein-protein interactions using complex formation assays in Cos cells.
Main Results:
- Deletion or mutation of the 129-145 domain inactivated c-Myc's transforming ability while retaining transcriptional activation.
- This domain is essential for the dominant negative effects of GAL4-Myc on c-Myc and E1A-mediated transformation.
- The c-Myc N-terminus forms a specific complex with a nuclear factor, which is disrupted by mutations in the 129-145 domain.
Conclusions:
- The c-Myc 129-145 domain is essential for oncogenic transformation and interacts with a nuclear factor.
- This nuclear factor is also required for adenovirus E1A-mediated transformation, suggesting a common pathway.
- Targeting this interaction could offer new therapeutic strategies for cancers driven by c-Myc or related pathways.