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I. GEORGE MILLER

I. General Description of Work in our Lab.
Our laboratory studies two human tumor viruses of the gamma herpesvirus group: Epstein-Barr virus (EBV) and Kaposi's Sarcoma-Associated Herpesvirus (KSHV). EBV is etiologically associated with many cancers, including nasopharyngeal cancer, Hodgkin's lymphoma, immunoblastic lymphoma and Burkitt's lymphoma, as well as benign diseases such as Infectious Mononucleosis. KSHV is the cause of Kaposi's Sarcoma, primary effusion lymphoma, and Multicentric Castleman's disease, a B cell lymhoproliferative disorder. Our current studies focus on a general unsolved problem, namely the mechanisms of viral latency and reactivation.

Both viruses establish "latent states" in host cells, during which only a few viral genes are expressed. Following certain environmental stimuli that can be mimicked in the laboratory, the viruses become activated into lytic cycle replication and produce mature progeny. Our laboratory discovered viral proteins that control this switch in lymphoid cells: ZEBRA and Rta for EBV and ORF50 for KSHV. A large group of experiments are directed at understanding the control of expression and mechanism of action of these virally encoded transcription factors. One current focus is to understand the mechanisms that regulate the activity of these proteins. These experiments concentrate on the effects of regulatory regions on protein stability, DNA binding, post-translational modification, transcriptional activation and repression, target gene specificity, and roles in viral DNA replication.

Both EBV and KSHV are tightly controlled by the immune system. The incidence of EBV- and KSHV-associated cancers is much higher in immunosuppressed patients, such as those with AIDS or recipients of tissue or organ transplants. In studies of immunopathogenesis we have investigated the role of CD4+ T cells in controlling proliferation of EBV infected lymphocytes. We have also studied the physiologic role of an IL6 cytokine homologue encoded by KSHV.

II. Descriptions of Ongoing Projects.
Our work addresses the following questions:
A. Latency to Lytic Cycle Switch
1. How is expression of the EBV genes encoding ZEBRA and Rta controlled by epigenetic events, such as histone modifications and DNA methylation?
2. Which cellular proteins activate and repress ZEBRA and Rta expression?
3. How does phosphorylation of ZEBRA affect its action as a transcriptional activator, transcriptional repressor and origin of replication binding protein?
4. How do individual amino acid residues in the DNA recognition domain of ZEBRA play specific roles in activation of early and late viral gene expression?
5. How is DNA binding and transcriptional activation of EBV Rta regulated?
6. How is DNA binding, transcriptional activation and protein stability of KSHV ORF50 protein regulated?
7. What accounts for the refractory state of some EBV-containing B cells to lytic cycle activation?
B. Immunology and Pathogenesis
1. Which cells of the inate and adaptive immune systems specifically recognize autologous EBV-transformed B cells?
2. What effector mechanisms are used by immune cells to control proliferation and to kill autologous EBV-transformed B cells?
3. How does N-linked glycosylation enhance the function of an IL6 homologue encoded by KSHV?

Selected Publications
Chang, P .-J., Shedd, D. and Miller, G. Two subclasses of Kaposi's sarcoma-associated herpesvirus lytic cycle promoters distinguished by mutants of ORF50 protein deficient in binding to DNA. J. Virol. 79, 8750-8763 (2005)

Chen, L.-W., Chang, P.-J., Delecluse, H. -J. and Miller, G. Marked variation in response of consensus binding elements for the Rta protein of Epstein-Barr virus. J. Virol. 79, 9635-9650 (2005)

El-Guindy, A, Paek, S.Y., Countryman, J. and Miller, G. Identification of constitutive phosphorylation sites on the Epstein-Barr virus ZEBRA protein. J. Biol. Chem. 281, 3085-3095 (2006)

Bhaduri-Mcintosh, S. and Miller, G. Cells lytically infected with Epstein-Barr virus are detected and separable by immunoglobulins from EBV-seropositive individuals. J. Virological Methods 137, 103-114 (2006)

Heston, L., El-Guindy, A., Countryman, J., Dela Cruz, C., Delecluse, H. -J. and Miller, G. Amino acids in the basic domain of Epstein-Barr virus ZEBRA protein play distinct roles in DNA binding, activation of early lytic gene expression and promotion of viral DNA replication. J. Virol. 80, 9115-9133 (2006)

Last Updated 12-18-06