Week 2 - Experimental Tumour Viruses and Tumour Suppressor Genes Flashcards
Name 3 experimental DNA oncoviruses.
SV40
Polyoma Virus
Adenovirus
What is SV40 and what cells does it transform?
– Monkey virus
– Transforms human and mouse cells in culture
What is Polyoma Virus and what cells does it transform?
– Mouse virus
– Transforms human cells in culture
What is Adenovirus and what cells does it transform?
– Human virus
– Transforms mouse cells in culture
What is the difference between permissive and non-permissive cells?
A permissive cell or host is one that allows a virus to circumvent its defenses and replicate.
Describe the DNA of SV40 and how it replicates?
Replicates via dsDNA intermediate
Circular episome (DNA) within nucleus
Why is SV40 a good research tool fo studying?
- Small Genome (5000BP)
- Few Genes
- So easy to study
What is the significance of the SV40 Large T Antigen (Tag)?
Essential for Cell transformation
What is the action of the SV40 T-Antigen?
It inactivates the tumour supressor protein p53 and Rb.
What is the name given to p53?
Guardian of the Genome because of its role in conserving stability by preventing genome mutation
What is the role of P53? (2)
- Detects cellular stress, especially DNA damage
- Induces G2 cell cycle arrest
If failure to repair damage, it induces apoptosis.
Is TP53 mutated or not in tumours with viral aetiology?
No.
How is TP53 in high levels in tumours with viral aetiology but still allows the tumours to form?
The TP53 protein is inactive.
Describe the negative feedback system of TP53.
- Excess TP53 induces MDM2 gene
- MDM2 protein binds p53
- MDM2 targets P53 for lysosomal destruction.
What is P53’s anti-viral role?
- P53 amplifies the interferon response in virus
infected cells - P53 -/- cells fail to undergo apoptosis in
response to viral infection
(altruistic apoptosis)
