scholarly journals Identification of New Human Origins of DNA Replication by an Origin-Trapping Assay

2006 ◽  
Vol 26 (20) ◽  
pp. 7731-7746 ◽  
Author(s):  
Jeannine Gerhardt ◽  
Samira Jafar ◽  
Mark-Peter Spindler ◽  
Elisabeth Ott ◽  
Aloys Schepers
Keyword(s):  
Chromatin Immunoprecipitation ◽  
Origin Recognition Complex ◽  
Human Origins ◽  
Replication Origins ◽  
Barr Virus ◽  
Human Dna ◽  
The Family ◽  
Epstein Barr ◽  
Dyad Symmetry

ABSTRACT Metazoan genomes contain thousands of replication origins, but only a limited number have been characterized so far. We developed a two-step origin-trapping assay in which human chromatin fragments associated with origin recognition complex (ORC) in vivo were first enriched by chromatin immunoprecipitation. In a second step, these fragments were screened for transient replication competence in a plasmid-based assay utilizing the Epstein-Barr virus latent origin oriP. oriP contains two elements, an origin (dyad symmetry element [DS]) and the family of repeats, that when associated with the viral protein EBNA1 facilitate extrachromosomal stability. Insertion of the ORC-binding human DNA fragments in oriP plasmids in place of DS enabled us to screen functionally for their abilities to restore replication. Using the origin-trapping assay, we isolated and characterized five previously unknown human origins. The assay was validated with nascent strand abundance assays that confirm these origins as active initiation sites in their native chromosomal contexts. Furthermore, ORC and MCM2-7 components localized at these origins during G1 phase of the cell cycle but were not detected during mitosis. This finding extends the current understanding of origin-ORC dynamics by suggesting that replication origins must be reestablished during the early stages of each cell division cycle and that ORC itself participates in this process.

scholarly journals Differential Hyperacetylation of Histones H3 and H4 upon Promoter-Specific Recruitment of EBNA2 in Epstein-Barr Virus Chromatin

2003 ◽  
Vol 77 (14) ◽  
pp. 8166-8172 ◽  
Author(s):  
Nathalie Alazard ◽  
Henri Gruffat ◽  
Edwige Hiriart ◽  
Alain Sergeant ◽  
Evelyne Manet
Keyword(s):  
B Lymphocytes ◽  
Chromatin Immunoprecipitation ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Viral Promoters ◽  
Epstein Barr ◽  
Cellular Dna ◽  
First Time

ABSTRACT Epstein-Barr virus nuclear antigen 2 (EBNA2) is a transcriptional activator involved in the immortalization of B lymphocytes by the virus. EBNA2 is targeted to the promoters of its responsive genes, via interaction with cellular DNA-binding proteins. Using chromatin immunoprecipitation assays, we show for the first time the conditional recruitment of EBNA2 on two specific viral promoters in vivo and demonstrate a correlation between this recruitment and a local change in the acetylation of histones H3 and H4, which is promoter dependent.

scholarly journals EBV-LMP1 promotes radioresistance by inducing protective autophagy through BNIP3 in nasopharyngeal carcinoma

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
San Xu ◽  
Zhuan Zhou ◽  
Xingzhi Peng ◽  
Xuxiu Tao ◽  
Peijun Zhou ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Crucial Role ◽  
Epstein Barr Virus ◽  
Interacting Protein ◽  
Multiple Tumors ◽  
Barr Virus ◽  
Signaling Axis ◽  
Epstein Barr ◽  
Adenovirus E1b

AbstractStudies have indicated that dysfunction of autophagy is involved in the initiation and progression of multiple tumors and their chemoradiotherapy. Epstein–Barr virus (EBV) is a lymphotropic human gamma herpes virus that has been implicated in the pathogenesis of nasopharyngeal carcinoma (NPC). EBV encoded latent membrane protein1 (LMP1) exhibits the properties of a classical oncoprotein. In previous studies, we experimentally demonstrated that LMP1 could increase the radioresistance of NPC. However, how LMP1 contributes to the radioresistance in NPC is still not clear. In the present study, we found that LMP1 could enhance autophagy by upregulating the expression of BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3). Knockdown of BNIP3 could increase the apoptosis and decrease the radioresistance mediated by protective autophagy in LMP1-positive NPC cells. The data showed that increased BNIP3 expression is mediated by LMP1 through the ERK/HIF1α signaling axis, and LMP1 promotes the binding of BNIP3 to Beclin1 and competitively reduces the binding of Bcl-2 to Beclin1, thus upregulating autophagy. Furthermore, knockdown of BNIP3 can reduce the radioresistance promoted by protective autophagy in vivo. These data clearly indicated that, through BNIP3, LMP1 induced autophagy, which has a crucial role in the protection of LMP1-positive NPC cells against irradiation. It provides a new basis and potential target for elucidating LMP1-mediated radioresistance.

scholarly journals Epstein-Barr virus, B cell lymphoproliferative disease, and SCID mice: Modeling T cell immunotherapy in vivo

2011 ◽  
Vol 83 (9) ◽  
pp. 1585-1596 ◽  
Author(s):  
I. Johannessen ◽  
L. Bieleski ◽  
G. Urquhart ◽  
S.L. Watson ◽  
P. Wingate ◽  
...  
Keyword(s):  
T Cell ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Lymphoproliferative Disease ◽  
Scid Mice ◽  
Barr Virus ◽  
Cell Immunotherapy ◽  
Epstein Barr ◽  
T Cell Immunotherapy

scholarly journals Expression of the Epstein-Barr virus BamHI A fragment in nasopharyngeal carcinoma: evidence for a viral protein expressed in vivo.

1991 ◽  
Vol 65 (11) ◽  
pp. 6252-6259 ◽  
Author(s):  
K J Gilligan ◽  
P Rajadurai ◽  
J C Lin ◽  
P Busson ◽  
M Abdel-Hamid ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Viral Protein ◽  
Epstein Barr Virus ◽  
Barr Virus ◽  
Epstein Barr

scholarly journals Acyclovir Improves the Efficacy of Chemoradiation in Nasopharyngeal Cancer Containing the Epstein Barr Virus Genome

2020 ◽  
Author(s):  
Aditya Thandoni ◽  
Andrew Zloza ◽  
Devora Schiff ◽  
Malay Rao ◽  
Kwok-wai Lo ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Treatment Options ◽  
Immune Surveillance ◽  
Nasopharyngeal Cancer ◽  
Standard Of Care ◽  
Virus Genome ◽  
Barr Virus ◽  
Standard Of Care Treatment ◽  
Epstein Barr

AbstractNasopharyngeal carcinoma (NPC) is a malignancy endemic to East Asia and is caused by Epstein-Barr Virus (EBV)-mediated cancerous transformation of epithelial cells. The standard of care treatment for NPC involves radiation and chemotherapy. While treatment outcomes continue to improve, up to 50% of patients can be expected to recur by five years, and additional innovative treatment options are needed. We posit that a potential way to do this is by targeting the underlying cause of malignant transformation, namely EBV. One method by which EBV escapes immune surveillance is by undergoing latent phase replication, during which EBV expression of immunogenic proteins is reduced. However, chemoradiation is known to drive conversion of EBV from a latent to a lytic phase. This creates an opportunity for the targeting of EBV-infected cells utilizing anti-viral drugs. Indeed, we found that combining acyclovir with cisplatin and radiation significantly decreases the viability of the EBV-infected C666-1 cell line. Western blot quantification revealed a resultant increase of thymidine kinase (TK) and apoptosis-inducing mediators, cleaved PARP (cPARP) and phosphorylated ERK (pERK). These studies suggest that the addition of anti-viral drugs to frontline chemoradiation may improve outcomes in patients treated for EBV-related NPC and future in vivo and clinical studies are needed.

Transient Immunodeficiency During Asymptomatic Epstein-Barr Virus Infection

PEDIATRICS ◽  
1983 ◽  
Vol 71 (6) ◽  
pp. 964-967
Author(s):  
THOMAS J. BOWEN ◽  
RALPH J. WEDGWOOD ◽  
HANS D. OCHS ◽  
WERNER HENLE
Keyword(s):  
Epstein Barr Virus ◽  
Mononuclear Cells ◽  
Epstein Barr Virus Infection ◽  
Peripheral Blood Mononuclear ◽  
Immunoglobulin Synthesis ◽  
Barr Virus ◽  
Ebv Infection ◽  
Epstein Barr

In vivo and in vitro humoral and cellular immune responses were studied in a 2½-year-old girl immediately before, during, and after an asymptomatic infection with Epstein-Barr virus. During the acute EBV infection, the patient's peripheral blood mononuclear cells were deficient in immunoglobulin synthesis and suppressed the in vitro immunoglobulin synthesis of normal allogeneic cells. In vitro mitogen transformation of lymphocytes was reduced. In vivo antibody responses to the T cell-dependent antigens bacteriophage φX 174 and Keyhole limpet hemocyanin were markedly depressed. These studies suggest that suppressor cells induced during acute EBV infection not only suppress immunoglobulin synthesis in vitro, but also interfere with in vivo antibody synthesis.

scholarly journals Epstein-Barr Virus (EBV)-Specific Cytotoxic T Lymphocytes for the Treatment of Patients With EBV-Positive Relapsed Hodgkin's Disease

Blood ◽  
1998 ◽  
Vol 91 (8) ◽  
pp. 2925-2934 ◽  
Author(s):  
Marie A. Roskrow ◽  
Nobuhiro Suzuki ◽  
Yan-jun Gan ◽  
John W. Sixbey ◽  
Catherine Y.C. Ng ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Cytotoxic T Lymphocytes ◽  
Hodgkin's Disease ◽  
Epstein Barr Virus ◽  
Hodgkin’S Disease ◽  
Barr Virus ◽  
Specific Ctls ◽  
Epstein Barr ◽  
Relapsed Disease

Adoptive transfer of Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTLs) is effective prophylaxis and treatment of EBV-positive immunoblastic lymphoma in immunocompromised patients. In 50% of patients with Hodgkin's disease, the tumor cells are EBV antigen-positive and may therefore also be suitable targets for treatment with virus-specific CTLs. However, Hodgkin's disease may produce several inhibitory effects on immune induction and effector function in vivo, which may preclude the generation or effector function of CTLs reactive against EBV viral proteins, including those expressed by the tumor cells. We have investigated whether EBV-specific CTLs could be generated ex vivo from 13 patients with Hodgkin's disease: nine with active relapsed disease and four who were in clinical remission after a first or subsequent relapse. CTL lines were successfully generated from nine of 13 patients (five active disease, four remission). Although these lines had an abnormal pattern of expansion comparable to EBV-specific CTLs generated from normal donors, their phenotype was normal except for reduced expression of the zeta chain of the T-cell receptor (TCR). Their cytotoxicity was also compared to EBV-specific lines generated from normal donors and included activity against LMP2a, one of the three weakly immunogenic viral antigens expressed by Hodgkin's tumor cells. To assess the activity of the CTLs in vivo, they were gene-marked and infused into three patients with multiply relapsed disease. The CTLs persisted for more than 13 weeks postinfusion and retained their potent antiviral effects in vivo, thereby enhancing the patient immune response to EBV. This approach may therefore have value in the treatment of EBV-positive Hodgkin's disease.

scholarly journals Common Epstein-Barr virus (EBV) type-1 variant strains in both malignant and benign EBV-associated disorders

Blood ◽  
1996 ◽  
Vol 87 (4) ◽  
pp. 1579-1585 ◽  
Author(s):  
V Schuster ◽  
G Ott ◽  
S Seidenspinner ◽  
HW Kreth
Keyword(s):  
Gastric Carcinoma ◽  
Epstein Barr Virus ◽  
Hodgkin's Lymphoma ◽  
Sequence Pattern ◽  
Barr Virus ◽  
Ebv Infection ◽  
Epstein Barr

In the present study, Epstein-Barr virus (EBV) isolates from 18 malignant tumors (angioimmunoblastic lymphadenopathy [AILD], n = 4; Hodgkin's disease [HD], n = 3; pleomorphic T-cell non-Hodgkin's lymphoma [T-NHL], n = 1; B-cell non-Hodgkin's lymphoma [B-NHL], n = 8; gastric carcinoma, n = 2) as well as from 10 tonsils of EBV- seropositive children and from peripheral blood mononuclear cells of 12 children with uncomplicated infectious mononucleosis (IM) and of a boy with severe chronic active EBV infection were genotyped in the EBV nuclear antigen-2 (EBNA-2) gene. A total of 40 of 41 isolates harbored EBV type 1; in 1 specimen (tonsil), only EBV type 2 was found. Further molecular characterization of EBV type-1 wild-type isolates in the EBNA- 2 gene and in the 40-kb distant EBV-encoded small RNAs (EBER) region showed that different groups of stable EBV type-1 variant strains exist in vivo both in benign and malignant lymphatic tissue. Group 1 is composed of EBV type-1 isolates (B-NHL, n = 3; T-NHL, n = 1; HD, n = 1; IM, n = 4) that showed a B95–8-like DNA sequence pattern in both viral genes. Group 2 isolates (HD, n = 1; AILD, n = B-NHL, n = 1; tonsils of EBV-seropositive children, n = 9; IM, n = 20 showed a nucleotide change at position 49095 in the EBNA-2 gene, leading to an amino acid substitution (Pro-->Ser), and EBV type-2 sequences in the EBER region. EBV type-1 isolates that fall into group 3 (AILD, n = 3; HD, n = 1; B- NHL, n = 4; gastric carcinoma, n = 2; IM, n = 6; severe chronic active EBV infection, n = 1) were characterized by typical nucleotide changes and a 3-bp insertion (CTC; extra Leu residue) in the EBNA-2 gene and an EBV type-2-specific sequence pattern in the EBER region. These EBV type- 1 variant strains may represent the most prevalent circulating EBV type- 1 strains in the exposed population and seem not to be restricted to a certain EBV-associated disease or tumor type. However, analysis of more EBV isolates from benign and malignant lesions must show whether more EBV type-1 substrains exist in vivo.

scholarly journals MicroRNA-18a promotes cancer progression through SMG1 suppression and mTOR pathway activation in nasopharyngeal carcinoma

2019 ◽  
Vol 10 (11) ◽  
Author(s):  
ShiJuan Mai ◽  
RuoWen Xiao ◽  
Lu Shi ◽  
XiaoMin Zhou ◽  
Te Yang ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Cancer Progression ◽  
Ectopic Expression ◽  
Mtor Pathway ◽  
Migration And Invasion ◽  
Clinical Samples ◽  
Antitumor Effects ◽  
Barr Virus ◽  
Epstein Barr

Abstract miR-18a has been reported to be upregulated in nasopharyngeal carcinoma (NPC) tissues by microarray assays. However, the roles and the underlying mechanisms of miR-18a in NPC remain poorly understood. Here we demonstrated by real-time RT-PCR that miR-18a expression is upregulated in NPC tissues, and positively correlated with tumor size and TNM stage. Moreover, miR-18a expression could be upregulated by NF-κB activation or Epstein-Barr virus encoded latent membrane protein 1 expression. The ectopic expression of miR-18a promoted NPC cell proliferation, migration and invasion, while the repression of miR-18a had opposite effects. Candidate genes under regulation by miR-18a were screened out through a whole-genome microarray assay, further identified by a reporter assay and verified in clinical samples. SMG1, a member of the phosphoinositide 3-kinase-related kinases family and an mTOR antagonist, was identified as functional target of miR-18a. Our results confirmed that miR-18a exerts its oncogenic role through suppression of SMG1 and activation of mTOR pathway in NPC cells. Importantly, in vivo xenograft tumor growth in nude mice was effectively inhibited by intratumor injection of miR-18a antagomir. Our data support an oncogenic role of miR-18a through a novel miR-18a/SMG1/mTOR axis and suggest that the antitumor effects of antagomir-18a may make it suitable for NPC therapy.

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