EBV is the casual agent of infectious mononucleosis and is associated with the development of both B-cell and epithelial cell malignancies including the endemic form of Burkitt's lymphoma, post-transplantation lympho-proliferative diseases, AIDS-associated lymphomas, Hodgkin's disease and undifferentiated nasopharyngeal carcinoma. Viral genes expressed during the latent phase of the EBV life cycle are growth promoting and are responsible for EBV's link to these human cancers. However, it has been known for some time that the lytic phase of the EBV life cycle occurs in differentiated and/or growth arrested tissues. We have recently found that the lytic switch gene, Zta, has potent cell growth inhibitory activity suggesting that EBV can actively promote this cell growth arrested status. Therefore, Zta may represent an evolutionary counterpart to the latency associated EBV gene products. The objectives of this proposal are to identify how Zta integrates into cell-cycle control pathways and to learn how interactions with key cell- cycle control proteins influences progression through the EBV lytic replication cycle.
Our specific aims are: 1) Genetic analysis of Zta mediated cellular growth arrest. a) Generation of Zta mutants (rationale) b) Preliminary characterization of Zta mutants - analysis of dimerization/DNA binding, nuclear localization, transactivation. c) Genetic analysis of Zta mediated growth arrest, p21, p27, and p53 induction, and inhibition of c-Myc expression. 2) Yeast two -hybrid for screening Zta interacting factors. a)Library screening. b) Clone selection - rationale. c) Interaction studies. d) Functional analysis of Zta:Zta-targeting factor interactions. 3) Genetic analysis of Zta mediated latency disruption. a) Development of model system. b) Analysis of latency disruption by Zta mutants.
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