Proto-oncogenes - J. Michael Bishop (UCSF)

TL;DR

Proto-oncogenes were discovered through viral and cellular genetic studies.

Transcript

this story began in 1909 when pton Ral at the Rockefeller Institute discovered a virus that causes sarcomas in chickens Rouse saroma virus it was a complete mystery as to how this uh virus caused cancer until 1970 when Steven Martin at the University of California Berkeley U isolated a mutant of Rouser Kuma virus that demonstrated temperature sensi... Read More

Key Insights

• The discovery of proto-oncogenes began with the identification of Rous sarcoma virus in 1909, which causes cancer in chickens.
• In 1970, Steven Martin discovered a temperature-sensitive mutant of the virus, demonstrating that cancerous transformation could be reversed by temperature changes.
• This discovery indicated the presence of a gene responsible for cancer transformation, later identified as the src gene in Rous sarcoma virus.
• Rous sarcoma virus contains only four genes; three are for viral reproduction, and the fourth, src, is responsible for cancer transformation.
• The src gene was found to be acquired from normal cells, suggesting viruses can incorporate cellular genes into their genomes.
• Proto-oncogenes, cellular genes that can become oncogenes, were identified as common precursors to viral oncogenes.
• The hypothesis emerged that proto-oncogenes could become oncogenes within cells without viral intervention, leading to cancer.
• This discovery has significant implications for understanding cancer development and the genetic basis of oncogenesis.

Questions & Answers

Q: What was the initial discovery that led to the understanding of proto-oncogenes?

The initial discovery was the identification of the Rous sarcoma virus in 1909, which was found to cause cancer in chickens. This virus contained the src gene, which was later identified as a key player in cancer transformation, leading to the understanding of proto-oncogenes.

Q: How did Steven Martin's research contribute to the understanding of cancer transformation?

Steven Martin's research in 1970 involved a temperature-sensitive mutant of the Rous sarcoma virus, demonstrating that cancerous transformation could be reversed by changing the temperature. This indicated the presence of a specific gene responsible for transformation, which was later identified as the src gene.

Q: What is the significance of the src gene in the Rous sarcoma virus?

The src gene in the Rous sarcoma virus is significant because it is responsible for cancer transformation. It was discovered that this gene was acquired from normal cells, suggesting that viruses can incorporate cellular genes into their genomes, leading to the identification of proto-oncogenes.

Q: How many genes does the Rous sarcoma virus contain, and what are their functions?

The Rous sarcoma virus contains four genes. Three of these genes are responsible for viral reproduction, while the fourth gene, src, is responsible for cancer transformation. The src gene is not required for viral replication but plays a crucial role in oncogenesis.

Q: What hypothesis emerged from the discovery of proto-oncogenes?

The discovery of proto-oncogenes led to the hypothesis that these cellular genes could become oncogenes within cells without viral intervention. This means that changes in proto-oncogenes could lead to cancer, providing a new understanding of the genetic basis of oncogenesis.

Q: What are proto-oncogenes, and how do they relate to viral oncogenes?

Proto-oncogenes are normal cellular genes that can become oncogenes, leading to cancer. They were identified as common precursors to viral oncogenes, suggesting that viruses can acquire these cellular genes and incorporate them into their genomes, causing cancer transformation.

Q: How did the discovery of proto-oncogenes impact the understanding of cancer development?

The discovery of proto-oncogenes significantly impacted the understanding of cancer development by highlighting the genetic basis of oncogenesis. It showed that changes in normal cellular genes could lead to cancer, providing insights into how cancer develops and potential targets for treatment.

Q: Why is the src gene considered an accident of nature in the context of Rous sarcoma virus?

The src gene is considered an accident of nature because it was acquired by the Rous sarcoma virus from normal cellular genes during replication. This accidental incorporation into the viral genome led to the virus's ability to cause cancer, highlighting the role of proto-oncogenes in oncogenesis.

Summary & Key Takeaways

• The discovery of proto-oncogenes began with the identification of the Rous sarcoma virus in 1909, which was found to cause cancer in chickens. This virus led to the discovery of the src gene, a key player in cancer transformation.

• In 1970, Steven Martin's work on a temperature-sensitive mutant of the Rous sarcoma virus demonstrated that cancerous transformation could be reversed by changing the temperature, indicating the presence of a specific gene responsible for this transformation.

• The src gene in Rous sarcoma virus was discovered to be acquired from normal cellular genes, leading to the identification of proto-oncogenes as common precursors to viral oncogenes, which can become oncogenes within cells and lead to cancer.