Question

Consider the Rous Sarcoma Virus. Explain how its transduced gene (the oncogene) functions in comparison to how its normal cellular form functions (the proto-oncogene). How does this difference in function cause cancer? How is its mechanism of oncogenesis differ from a the mechanism of a nontransducing cancer virus like human herpes virus 8?

Answer 1

Solution: The c-Src is the proto-oncogene generally present in the eukaryotic cells. It codes for a non-receptor tyrosine kinase protein. It velongs to Src family of kinases. The three domains present in this kinase are SH2, SH3 and tyrosine kinase domains. They have specific developmental role by regulating the growth and differentiation of cells. Rous sarcoma virus(RSV) is a retrovirus that causes cancer in many eukaryotic organisms encodes v-Src gene . The RSV acquire this gene from host organism. The RSV make use of this proto-oncogene for inducing uncontrolled proliferation to host cells so that they get many fresh cells for infection. Presence of Src increases the virulence of RSV. The human herpes virus causes Kaposis's sarcoma. The Kaposi's sarcoma is commonly seen in AIDS patients. Unlike RSV, the herpesvirus is a DNA virus. The infection of human herpesvirus 8 occurs on immunocompromised people than normoal people. Study results shows that HIV protein Tat, synergistically increases the chemokine receptors and associated activation of NF-kappa B and NF-AT of HHV-8 infected cells. The levels of NF-kappa B and NF-AT accelerates cancer formation.