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Identifying genes regulated in a Myc-dependent manner
John D Watson1, Sara K Oster, Mary Shago
1Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
Abstract:
The c-myc proto-oncogene can direct a diverse array of biological activities, including cell cycle progression, apoptosis, and differentiation. It is believed that Myc can affect this wide variety of activities by functioning as a regulator of gene transcription, although few targets have been identified to date. To delineate the molecular program regulated downstream of Myc, we used a cDNA microarray approach and identified 52 putative targets out of >6000 cDNAs analyzed. To further distinguish the subset of genes whose regulation was dependent upon Myc per se from those regulated in response to activation of general mitogenic or apoptotic programs, the putative cDNA targets were then screened by a series of assays. By this approach 37 putative targets were ruled out and 15 Myc target genes were uncovered. Interestingly, comparing our results with other high throughput screens reveals that certain putative Myc targets previously reported are shown not to be regulated downstream of Myc (e.g. ribosomal proteins, HSP90beta), whereas others are further supported by our analyses (e.g. pdgfbetar, nucleolin). The identity of genes specifically regulated downstream of Myc provides the critical tools required to understand the role Myc holds in the transformation process and to delineate how Myc functions as a regulator of gene transcription.
Insights
Researchers identified 15 Myc target genes using cDNA microarrays to understand how the c-myc proto-oncogene regulates gene transcription, cell cycle, and apoptosis.
Area of Science:
- Molecular Biology
- Oncology
- Gene Regulation
Background:
- The c-myc proto-oncogene regulates critical cellular processes like cell cycle progression, apoptosis, and differentiation.
- Myc's role as a gene transcription regulator is established, but specific downstream targets remain largely unidentified.
Purpose of the Study:
- To identify and validate genes directly regulated by Myc.
- To delineate the molecular mechanisms underlying Myc's diverse biological functions.
Main Methods:
- Utilized a cDNA microarray approach to screen over 6000 cDNAs for potential Myc targets.
- Employed a series of assays to validate putative targets and distinguish Myc-dependent regulation from general cellular responses.
Main Results:
- Identified 52 putative Myc target genes from the initial microarray screen.
- Validated and uncovered 15 specific Myc target genes after rigorous screening.
- Contradicted previous findings, showing certain reported targets (e.g., ribosomal proteins) are not Myc-regulated, while supporting others (e.g., pdgfbetar).
Conclusions:
- Established a validated set of 15 Myc target genes crucial for understanding Myc's role in cellular processes.
- Provided essential tools for further research into Myc's function in transformation and gene transcription regulation.
- Highlighted the importance of rigorous validation in high-throughput screening studies for identifying direct gene targets.