Epigenetic regulation of gene expression plays a critical role in many fundamental biological processes in eukaryotes. We have focused on defining epigenetic mechanisms, involving post-translation modification of chromatin proteins, in the life cycle of Kaposi's sarcoma herpesvirus (KSHV), which is an etiological agent of Kaposi's sarcoma (KS), an AIDS-associated malignancy. This virus exhibits a latent phase in infected cells in which only a few viral genes are expressed. Cell signaling pathways can reactivate latent cells to produce virus through a temporal cascade that regulates expression of nearly 100 viral genes. Thus, KSHV is a very attractive model to study epigenetic mechanisms that affect chromatin structure and dynamics, which are key processes regulating transcription in eukaryotic cells. The small ubiquitin-like modifier (SUMO) is a protein that regulates a wide variety of cellular processes, including heterochromatin formation, by covalent attachment (i.e., sumoylation) to a diverse array of target proteins. Sumoylation, like phosphorylation, serves as a post-translational signal molecule to transmit signals to down-stream targets containing a SUMO-interacting motif (SIM);these targets include proteins that impact chromatin structure that generally silence transcription. Our recent studies show that the main viral transcriptional transactivator, K-Rta, is a SUMO-targeting ubiquitin (Ub) ligase, which degrades SUMO- modified proteins. We hypothesize that this SUMO-targeting Ub ligase function is important for K-Rta to initiate the lytic (productive) phase of KSHV replication by disrupting the repressive environment surrounding of the viral episome in latently infected cells. This repressive environment is established by the viral latency- associated nuclear antigen (LANA), which is a SUMO-binding protein that tethers viral episomes to heterochromatic regions of host cell chromosomes and thereby maintains the latent state of the virus. This proposal will test the hypothesis that the regulation of SUMO modification plays a key role in the KSHV life cycle in both establishment of latency and reactivation of this virus by modulating the structure of viral chromatin. In the first Aim, we will investigate the role of K-Rta as a SUMO-dependent ubiquitin ligase in KSHV replication. In the second Aim, the potential mechanisms whereby K-Rta acts in a SUMO-dependent manner and affects the epigenetic signature of viral chromatin will be analyzed. Taken together, these studies will define a new role of K-Rta, as well as LANA, in KSHV replication, and will provide insights into the post- translational modifications and chromatin remodeling that govern latency and reactivation.

Public Health Relevance

The research in this R01 grant application on KSHV will produce a new understanding oF regulation of gene expression and epigenetic control. Our research will provide fundamental knowledge regarding the mechanisms of viral reactivation and could produce innovative approaches for the treatment of infectious disease, especially cancer caused by this tumorigenic virus.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01CA147791-05
Application #
8657867
Study Section
AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
Program Officer
Read-Connole, Elizabeth Lee
Project Start
Project End
Budget Start
Budget End
Support Year
5
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of California Davis
Department
Dermatology
Type
Schools of Medicine
DUNS #
City
Davis
State
CA
Country
United States
Zip Code
95618
Bhatt, Aadra Prashant; Wong, Jason P; Weinberg, Marc S et al. (2016) A viral kinase mimics S6 kinase to enhance cell proliferation. Proc Natl Acad Sci U S A 113:7876-81
Schreiber, Claire A; Sakuma, Toshie; Izumiya, Yoshihiro et al. (2015) An siRNA Screen Identifies the U2 snRNP Spliceosome as a Host Restriction Factor for Recombinant Adeno-associated Viruses. PLoS Pathog 11:e1005082
Nakajima, Ken-ichi; Zhu, Kan; Sun, Yao-Hui et al. (2015) KCNJ15/Kir4.2 couples with polyamines to sense weak extracellular electric fields in galvanotaxis. Nat Commun 6:8532
Kim, Kevin Y; Wang, Don-Hong; Campbell, Mel et al. (2015) PRMT4-mediated arginine methylation negatively regulates retinoblastoma tumor suppressor protein and promotes E2F-1 dissociation. Mol Cell Biol 35:238-48
Campbell, Mel; Kim, Kevin Y; Chang, Pei-Ching et al. (2014) A lytic viral long noncoding RNA modulates the function of a latent protein. J Virol 88:1843-8
Campbell, Mel; Kung, Hsing-Jien; Izumiya, Yoshihiro (2014) Long non-coding RNA and epigenetic gene regulation of KSHV. Viruses 6:4165-77
Kim, Kevin Y; Huerta, Steve B; Izumiya, Chie et al. (2013) Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen regulates the KSHV epigenome by association with the histone demethylase KDM3A. J Virol 87:6782-93
Toth, Zsolt; Brulois, Kevin; Lee, Hye-Ra et al. (2013) Biphasic euchromatin-to-heterochromatin transition on the KSHV genome following de novo infection. PLoS Pathog 9:e1003813
Izumiya, Yoshihiro; Kobayashi, Keisuke; Kim, Kevin Y et al. (2013) Kaposi's sarcoma-associated herpesvirus K-Rta exhibits SUMO-targeting ubiquitin ligase (STUbL) like activity and is essential for viral reactivation. PLoS Pathog 9:e1003506
Campbell, Mel; Chang, Pei-Ching; Huerta, Steve et al. (2012) Protein arginine methyltransferase 1-directed methylation of Kaposi sarcoma-associated herpesvirus latency-associated nuclear antigen. J Biol Chem 287:5806-18

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