Lack of a mechanism for faithful partition and maintenance of the KSHV genome

Ueda, Keiji; Sakakibara, Shuhei; Ohsaki, Eriko; Yada, Kaori

doi:10.1016/j.virusres.2006.07.002

Cited by 18 publications

(17 citation statements)

References 43 publications

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“…KSHV genomes replicate once per cell cycle during latency and are partitioned perpetually into daughter cells along with host chromosomes during mitosis (3,4,63). KSHV-infected PEL cells maintain between 50 and 100 copies of episomes per cell, and the copy number appears to be retained at the same number over time after multiple rounds of cell division (2,11,42,57). Since LANA has no detectable polymerase or helicase activity required for DNA replication, this strongly suggests that replication of the KSHV genome is dependent on enzymes that contain these activities and core components of the cellular replication machinery (42).…”

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confidence: 99%

Kaposi's Sarcoma-Associated Herpesvirus-Encoded LANA Recruits Topoisomerase IIβ for Latent DNA Replication of the Terminal Repeats

Purushothaman

McDowell

McGuinness

et al. 2012

J Virol

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The latency-associated nuclear antigen (LANA) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) plays a major role in maintaining latency and is critical for the perpetual segregation of viral episomes to the progeny nuclei of newly divided cells. LANA binds to KSHV terminal repeat (TR) DNA and tethers the viral episomes to host chromosomes through the association of chromatin-bound cellular proteins. TR elements serve as potential origin sites of KSHV replication and have been shown to play important roles in latent DNA replication and transcription of adjacent genes. Affinity chromatography and proteomics analysis using KSHV TR DNA and the LANA binding site as the affinity column identified topoisomerase IIβ (TopoIIβ) as a LANA-interacting protein. Here, we show that TopoIIβ forms complexes with LANA that colocalize as punctuate bodies in the nucleus of KSHV-infected cells. The specific TopoIIβ binding region of LANA has been identified to its N terminus and the first 32 amino acid residues containing the nucleosome-binding region crucial for binding. Moreover, this region could also act as a dominant negative to disrupt association of TopoIIβ with LANA. TopoIIβ plays an important role in LANA-dependent latent DNA replication, as addition of ellipticine, a selective inhibitor of TopoII, negatively regulated replication mediated by the TR. DNA break labeling and chromatin immunoprecipitation assay using biotin-16-dUTP and terminal deoxynucleotide transferase showed that TopoIIβ mediates a transient DNA break on viral DNA. These studies confirm that LANA recruits TopoIIβ at the origins of latent replication to unwind the DNA for replication.

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confidence: 99%

Kaposi's Sarcoma-Associated Herpesvirus-Encoded LANA Recruits Topoisomerase IIβ for Latent DNA Replication of the Terminal Repeats

Purushothaman

McDowell

McGuinness

et al. 2012

J Virol

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“…One view is that physical linkage provides a partitioning function to ensure that the episomes are segregated equally into each daughter cell at cell division and are duly incorporated into the new nuclei. The situation may be more complex, because the expression of LANA alone is not sufficient to maintain TR-containing episomes for extended periods without drug selection (25,66) and there is evidence from studies of papillomaviruses that tethering factors may also serve a gene-regulatory function (44).…”

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confidence: 99%

The Latency-Associated Nuclear Antigen Interacts with MeCP2 and Nucleosomes through Separate Domains

Matsumura

Persson

Wong

et al. 2010

J Virol

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“…There was no significant enhancement of transcriptional activity in BJAB cells, but the presence of the full KSHV genome in a BAC (BJAB-BAC36) indeed enhanced transcriptional activity. Consistently, a Ϫ898 Luc reporter showed high activity in BJAB cells containing the full-length KSHV genome in the BAC (37,41).…”

Section: Discussionmentioning

confidence: 57%

“…To understand how ANGPT-1 was upregulated in KSHV-infected PEL cells and how KSHV contributed to ANGPT-1 gene expression, we constructed ANGPT-1 promoter-luciferase reporter constructs (Ϫ898 to ϩ490 of Luc, where ϩ1 is the transcription start site and ϩ490 is the A in ATG, the ANGPT-1 translation initiation codon) and measured their transcriptional activity. These constructs were tested in KSHV-infected or uninfected cells and BJAB-BAC36 cells, which contained the full KSHV genome in a bacterial artificial chromosome (BAC) (26,37). The activation of the reporter gene containing the regulatory region of ANGPT-1 was greater than that in the control, i.e., 5.1-fold greater in BC3 cells, 15.1-fold greater in BCBL1 cells, and 23.5-fold greater in TY1 cells, and its activation was 4.1-fold greater in BJAB-BAC36 cells but not in BJAB cells (Fig.…”

Section: The Luciferase Activity Of the Regulatory Region Of Angpt-1 mentioning

confidence: 99%

Mechanism of Angiopoietin-1 Upregulation in Kaposi's Sarcoma-Associated Herpesvirus-Infected PEL Cell Lines

Zheng

Ohsaki

Ueda

2015

J Virol

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Angiopoietin-1 (ANGPT-1) is a secreted glycoprotein that was first characterized as a ligand of the Tie2 receptor. In a previous study using microarray analysis, we found that the expression of ANGPT-1 was upregulated in Kaposi's sarcoma-associated herpesvirus (KSHV)-infected primary effusion lymphoma (PEL) cell lines compared with that in uninfected Burkitt and other leukemia cell lines. Other authors have also reported focal expression of ANGPT-1 mRNA in biopsy specimens of Kaposi's sarcoma (KS) tissue from patients with AIDS. Here, to confirm these findings, we examined the expression and secretion levels of ANGPT-1 in KSHV-infected PEL cell lines and address the mechanisms of ANGPT-1 transcriptional regulation. We also showed that ANGPT-1 was expressed and localized in the cytoplasm and secreted into the supernatant of KSHV-infected PEL cells. Deletion studies of the regulatory region revealed that the region encompassing nucleotides ؊143 to ؊125 of the ANGPT-1-regulating sequence was responsible for this upregulation. Moreover, an electrophoretic mobility shift assay and chromatin immunoprecipitation, followed by quantitative PCR, suggested that some KSHV-infected PEL cell line-specific DNA-binding factors, such as OCT-1, should be involved in the upregulation of ANGPT-1 in a sequence-dependent manner. IMPORTANCEWe confirmed that ANGPT-1 was expressed in and secreted from KSHV-infected PEL cells and that the transcriptional activity of ANGPT-1 was upregulated. A 19-bp fragment was identified as the region responsible for ANGPT-1 upregulation through binding with OCT-1 as a core factor in PEL cells. This study suggests that ANGPT-1 is overproduced in KSHV-infected PEL cells, which could affect the pathophysiology of AIDS patients with PEL. K aposi's sarcoma (KS)-associated herpesvirus (KSHV), also known as human herpesvirus 8, belongs to the gamma-2 herpesvirus family, which was first identified in KS lesions (1). Epstein-Barr virus (EBV), which also belongs to the gamma-2 herpesvirus family, is frequently associated with malignancies such as Burkitt lymphoma (BL) and nasopharyngeal carcinoma (NPC) (2). KSHV is also associated with several malignancies, i.e., two lymphoproliferative disorders, primary effusion lymphoma (PEL) (3) and multicentric Castleman's disease, as well as KS (4, 5).It has been reported that KSHV infects various cell types, such as B cells, blood vessel endothelial cells (BECs), lymphatic endothelial cells (LECs), Vero cells, and HEK293 cells (6-9). After infection, KSHV utilizes latency as a default pathway of replication (1, 7). Though viral gene expression profiles might differ between BECs and LECs (10), KSHV is predominantly in latency with its genome binding to the host cell chromosome (10, 11) and governs host gene expression profiles (12) as other viruses do (13, 14). Most KSHV-infected cells are latently infected, and only a limited number of viral genes are expressed in latency: latency-associated nuclear antigen (LANA), viral cyclin (vCYC), viral FLICE inhibitory prote...

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Lack of a mechanism for faithful partition and maintenance of the KSHV genome

Cited by 18 publications

References 43 publications

Kaposi's Sarcoma-Associated Herpesvirus-Encoded LANA Recruits Topoisomerase IIβ for Latent DNA Replication of the Terminal Repeats

Kaposi's Sarcoma-Associated Herpesvirus-Encoded LANA Recruits Topoisomerase IIβ for Latent DNA Replication of the Terminal Repeats

The Latency-Associated Nuclear Antigen Interacts with MeCP2 and Nucleosomes through Separate Domains

Mechanism of Angiopoietin-1 Upregulation in Kaposi's Sarcoma-Associated Herpesvirus-Infected PEL Cell Lines

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