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Expression of the avian gag-myc oncogene in Saccharomyces cerevisiae
P Durrens1, A Fournier, L Desfarges
1Laboratoire de Génétique, Unité Associée du Centre National de la Recherche Scientifique URA, Talence, France.
Abstract:
The gag-myc oncogenic sequence of the avian retrovirus MC29 was first inserted in a multicopy expression vector allowing its expression in Saccharomyces cerevisiae. The oncogene transcripts were detected in yeast by Northern blot hybridization and gag-myc proteins were revealed by immunoprecipitation. On solid medium, the average size of gag-myc transformant colonies was smaller than control. In liquid cultures, the gag-myc strains had a doubling time of 4.7 h compared with 3.1 h in the controls. In one of the recipient strains, and after an initial transient period of 5 days, the gag-myc transformants became physiologically indistinguishable from control. In another recipient strain, the slow-growth phenotype is permanent. Plasmid instability is increased in gag-myc transformants. When a single copy of the gag-myc gene was inserted in a yeast chromosome, no phenotype was observed, showing that slow growth is the consequence of plasmid loss.
Insights
The avian retrovirus MC29 gag-myc oncogene expression in yeast (Saccharomyces cerevisiae) caused slow growth, linked to plasmid instability. This phenotype was absent when the gene was integrated into the yeast chromosome.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Oncogene Research
Background:
- The gag-myc oncogene from avian retrovirus MC29 is a potent oncogene.
- Understanding oncogene expression and its effects in model organisms like yeast is crucial for cancer research.
Purpose of the Study:
- To investigate the expression and phenotypic consequences of the gag-myc oncogene in Saccharomyces cerevisiae.
- To determine if gag-myc expression impacts yeast growth and physiology.
Main Methods:
- Insertion of the gag-myc oncogene into a multicopy expression vector for yeast.
- Detection of gag-myc transcripts via Northern blot hybridization.
- Detection of gag-myc proteins using immunoprecipitation.
- Growth rate analysis on solid and liquid media.
- Assessment of plasmid stability and chromosomal integration.
Main Results:
- gag-myc expression was confirmed in yeast.
- gag-myc transformants exhibited smaller colony sizes and longer doubling times (4.7 h vs. 3.1 h).
- The slow-growth phenotype was associated with increased plasmid instability and was absent upon chromosomal integration.
- Phenotype reversibility was observed in one yeast strain.
Conclusions:
- The slow-growth phenotype in yeast expressing the gag-myc oncogene is primarily a consequence of plasmid instability, not direct cellular transformation.
- Saccharomyces cerevisiae serves as a valuable model for studying the impact of oncogene expression and plasmid dynamics.