Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is etiologically linked with KS, primary effusion lymphomas (PELs) and multicentric Castleman's disease. These diseases occur in AIDS and in other patients and current therapies are limited. KSHV latently infects the vast majority of tumor cells and viral DNA persists as a multiple copy, extrachromosomal, circular episome. To persist in proliferating cells, episomes must replicate and efficiently segregate to daughter nuclei. KSHV latency associated nuclear antigen (LANA) binds terminal repeat (TR) DNA to mediate KSHV episome persistence. LANA mediates TR DNA replication and binds TR DNA to tether episomes to mitotic chromosomes for efficient segregation to progeny nuclei. LANA is essential for KSHV episome maintenance and central to viral latency. The N- and C-terminal regions are essential for LANA function and bind mitotic chromosomes and TR DNA. However, the role(s) of internal domains in LANA mediated episome maintenance are unknown. We have now identified a 68 amino acid internal LANA region which exerts a critical effect on episome maintenance. We have also found that poly(ADP-ribose) polymerase-1 (PARP1) exerts a potent inhibitory effect on LANA mediated episome persistence. Small molecule inhibitors of LANA function would be powerful tools to probe LANA function and viral latency and would provide new therapeutic strategies. However, currently, no such inhibitors have been identified or developed. This work will address critical aspects of LANA biology. The newly identified internal LANA region critical for episome maintenance will be investigated, including its mechanism of action. Such knowledge will provide insight into the basic mechanisms of LANA mediated episome persistence. The biology of PARP1 inhibition of episome maintenance will be investigated. Study of this area is critical since PARP1 appears to be a key component of the host response to KSHV infection. Small molecule inhibitors of LANA function will be identified. These compounds will provide novel probes of KSHV latency and serve as potential therapeutic and preventive agents for KSHV malignancy.

Public Health Relevance

Kaposi's sarcoma-associated herpesvirus (KSHV) has a causative role in several human malignancies. KSHV infects and persists in tumor cells. This work investigates the mechanisms by which KSHV is able to persist and survive in the tumor cells. A better understanding of this viral persistence may allow development of strategies which prevent or treat KSHV tumors.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
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Read-Connole, Elizabeth Lee
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Brigham and Women's Hospital
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Sun, Qiming; Tsurimoto, Toshiki; Juillard, Franceline et al. (2014) Kaposi's sarcoma-associated herpesvirus LANA recruits the DNA polymerase clamp loader to mediate efficient replication and virus persistence. Proc Natl Acad Sci U S A 111:11816-21
De Leon Vazquez, Erika; Juillard, Franceline; Rosner, Bernard et al. (2014) A short sequence immediately upstream of the internal repeat elements is critical for KSHV LANA mediated DNA replication and impacts episome persistence. Virology 448:344-55
Vazquez, Erika De Leon; Carey, Vincent J; Kaye, Kenneth M (2013) Identification of Kaposi's sarcoma-associated herpesvirus LANA regions important for episome segregation, replication, and persistence. J Virol 87:12270-83
Correia, Bruno; Cerqueira, Sofia A; Beauchemin, Chantal et al. (2013) Crystal structure of the gamma-2 herpesvirus LANA DNA binding domain identifies charged surface residues which impact viral latency. PLoS Pathog 9:e1003673
Rodrigues, Lenia; Popov, Nikita; Kaye, Kenneth M et al. (2013) Stabilization of Myc through heterotypic poly-ubiquitination by mLANA is critical for ýý-herpesvirus lymphoproliferation. PLoS Pathog 9:e1003554
Dheekollu, Jayaraju; Chen, Horng-Shen; Kaye, Kenneth M et al. (2013) Timeless-dependent DNA replication-coupled recombination promotes Kaposi's Sarcoma-associated herpesvirus episome maintenance and terminal repeat stability. J Virol 87:3699-709
Ballestas, Mary E; Kaye, Kenneth M (2011) The latency-associated nuclear antigen, a multifunctional protein central to Kaposi's sarcoma-associated herpesvirus latency. Future Microbiol 6:1399-413
De Leon Vazquez, Erika; Kaye, Kenneth M (2011) Rapid and quantitative assessment of KSHV LANA-mediated DNA replication. Arch Virol 156:1323-33
De León Vázquez, Erika; Kaye, Kenneth M (2011) The internal Kaposi's sarcoma-associated herpesvirus LANA regions exert a critical role on episome persistence. J Virol 85:7622-33
Kelley-Clarke, Brenna; De Leon-Vazquez, Erika; Slain, Katherine et al. (2009) Role of Kaposi's sarcoma-associated herpesvirus C-terminal LANA chromosome binding in episome persistence. J Virol 83:4326-37

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