The Minimal Replicator Element of the Kaposi's Sarcoma-Associated Herpesvirus Terminal Repeat Supports Replication in a Semiconservative and Cell-Cycle-Dependent Manner

Abstract

Kaposi's sarcoma-associated herpesvirus (KSHV) persists as episomes in infected cells by circularizing at the terminal repeats (TRs).Kaposi's sarcoma-associated herpesvirus (KSHV), discovered using a subtractive hybridization technique from the Kaposi sarcoma lesions, is also associated with at least two lymphoproliferative diseases, primary effusion lymphoma (PEL) and multicentric Castleman's disease (9-11, 17, 54, 59). KSHV persists as multicopy episomal DNA in infected cells with the expression of a small subset of genes (18,34,55,65). Expression of the latency-associated nuclear antigen (LANA) is considered one of the crucial signatures of KSHV infection. Serum from KSHV-positive patients was initially used for the detection of LANA in infected cells (16,32). LANA is a large nuclear protein detected in a punctate pattern in KSHV-infected cells (37,48). LANA dots, which roughly correspond to the number of KSHV episomal copies, range from 15 to 120 per cell (13, 23). Detection of LANA and KSHV genomic DNA in an immunofluorescent in situ hybridization assay on chromosome spreads of KSHV-infected cells showed perfect colocalization of genomic DNA with LANA dots, suggesting the involvement of LANA in episomal tethering (13).The role of LANA in the persistence of the KSHV genome was evaluated using the 33-kb left-end Z6 cosmid of KSHV in BJAB cells expressing LANA under G418 selection (4). Z6 cosmid DNA efficiently persisted in LANA-expressing cells,

Cellular Corepressor TLE2 Inhibits Replication-and-Transcription- Activator-Mediated Transactivation and Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus

“…ChIP assays. A chromatin immunoprecipitation (ChIP) assay was performed as described previously (68). Briefly, 1 ϫ 10 6 293/Bac36 cells transfected with TLE2 were used per assay.…”

Viral epigenomes in human tumorigenesis

“…DNA methylation is one of the strategies that some viruses use to avoid detection by the immune system (Butel, 2000;Verma et al, 2007); specifically, the deregulation of DNMT family members has been proposed as one of the mechanisms that modulate gene expression in these interactions (Li et al, 2005). Therapy with demethylating agents in this kind of pathology has not yet been used against solid tumors in vivo, but for example, DNMT3B inhibitors could potentially be useful in HCC (Park et al, 2007a).…”

“…LANA participates in the maintenance of the episome during latency. It also links the episome to the host cell chromosome and binds to the viral repeat elements (TR) of the viral genome to mediate its replication (Ballestas et al, 1999;Cotter and Robertson, 1999;Verma et al, 2007). The interactions between LANA and cellular and viral proteins, such as those encoded by p53, pRB or replication and transcription activator (Rta), among others, are summarized by zur Hausen (2006), who also reviews its regulatory role in the expression of genes involved in the main cellular pathways.…”

Identification of Properties of the Kaposi's Sarcoma-Associated Herpesvirus Latent Origin of Replication That Are Essential for the Efficient Establishment and Maintenance of Intact Plasmids

“…1A and C). Given that the synthesis of KSHV genomes is licensed (22), these observations likely indicate that a higher number of TRs provides KSHV plasmids with an increased probability that they will undergo synthesis.…”

“…The MRE, consisting of two LANA1-binding sites (LBS 1 and 2) and an upstream GC-rich replication element (RE), is the minimal element that supports synthesis of KSHV plasmids (17). LANA1 mediates licensed synthesis of the viral plasmid by binding to LBS 1 and 2 through its DNA-binding and dimerization domain located in the C terminus and recruiting the cellular origin recognition complex (ORC) (18)(19)(20)(21)(22). The partitioning of KSHV plasmids is thought to be mediated by tethering of viral plasmids to cellular chromosomes by LANA1.…”