scholarly journals Nuclear Factor κB-Dependent Activation of the Antiapoptotic bfl-1 Gene by the Epstein-Barr Virus Latent Membrane Protein 1 and Activated CD40 Receptor

2004 ◽  
Vol 78 (4) ◽  
pp. 1800-1816 ◽  
Author(s):  
Brendan N. D'Souza ◽  
Leonard C. Edelstein ◽  
Pamela M. Pegman ◽  
Sinéad M. Smith ◽  
Sinéad T. Loughran ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Lines ◽  
Promoter Activity ◽  
Epstein Barr Virus ◽  
Burkitt’S Lymphoma ◽  
Latent Membrane Protein ◽  
Latent Membrane Protein 1 ◽  
Mrna Levels ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Suppression of the cellular apoptotic program by the oncogenic herpesvirus Epstein-Barr virus (EBV) is central to both the establishment of latent infection and the development of EBV-associated malignancies. We have previously shown that expression of the EBV latent membrane protein 1 (LMP1) in Burkitt's lymphoma cell lines leads to increased mRNA levels from the cellular antiapoptotic bfl-1 gene (also known as A1). Furthermore, ectopic expression of Bfl-1 in an EBV-positive cell line exhibiting a latency type 1 infection protects against apoptosis induced by growth factor deprivation (B. N. D'Souza, M. Rowe, and D. Walls, J. Virol. 74:6652-6658, 2000). We now report that LMP1 drives bfl-1 promoter activity through interactions with components of the tumor necrosis factor receptor (TNFR)/CD40 signaling pathway. We present evidence that this process is NF-κB dependent, involves the recruitment of TNFR-associated factor 2, and is mediated to a greater extent by the carboxyl-terminal activating region 2 (CTAR2) relative to the CTAR1 domain of LMP1. Activation of CD40 receptor also led to increased bfl-1 mRNA levels and an NF-κB-dependent increase in bfl-1 promoter activity in Burkitt's lymphoma-derived cell lines. We have delineated a 95-bp region of the promoter that functions as an LMP1-dependent transcriptional enhancer in this cellular context. This sequence contains a novel NF-κB-like binding motif that is essential for transactivation of bfl-1 by LMP1, CD40, and the NF-κB subunit protein p65. These findings highlight the role of LMP1 as a mediator of EBV-host cell interactions and may indicate an important route by which it exerts its cellular growth transforming properties.

Subcellular localization of the latent membrane protein LMP-1 in Epstein-Barr virus infected cells by immunogold EM

1994 ◽  
Vol 52 ◽  
pp. 248-249
Author(s):  
D. N. Misra ◽  
R. M. Agostini ◽  
E. J. Yunis
Keyword(s):  
Membrane Protein ◽  
Subcellular Localization ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Hodgkin’S Disease ◽  
Burkitt’S Lymphoma ◽  
Latent Membrane Protein ◽  
Barr Virus ◽  
Infected Cells ◽  
Epstein Barr

Epstein-Barr virus (EBV) infection, prevalent in all human populations, is clinically silent in general, but causes infectious mononucleosis in some adolescents and B-lymphocyte proliferative disorders (LPDs) in immunocompromised individuals (e.g. AIDS infected; allograft recipients). EBV is also etiologically associated with African Burkitt’s lymphoma, nasopharyngeal carcinoma, and Hodgkin’s disease. The virus infects B lymphocytes and transforms them into lymphoblastoid cells which proliferate indefinitely in culture. The latently infected cells express an array of EBV gene products including 6 nuclear antigens (EBNAs), terminal proteins LMP-2A and LMP-2B, latent membrane protein LMP-1, and untranslated RNAs EBER 1 and EBER 2. These components are being extensively studied since they are involved in latency or proliferative transformation; LMP-1 has also shown oncogenic properties. In this work, we have used immunogold electron microscopy for precise subcellular localization of LMP-1 in EBV infected cell lines.Two human cell lines, P3HR-1 (Burkitt’s lymphoma) and CCL-113 (Hodgkin’s disease), obtained from ATCC, were grown in RPMI 1640 containing 20% fetal calf serum, 100 U/ml penicillin and 100 μg/ml streptomycin.

scholarly journals Epstein-Barr Virus Latent Membrane Protein 1 Induces Cellular MicroRNA miR-146a, a Modulator of Lymphocyte Signaling Pathways

2007 ◽  
Vol 82 (4) ◽  
pp. 1946-1958 ◽  
Author(s):  
Jennifer E. Cameron ◽  
Qinyan Yin ◽  
Claire Fewell ◽  
Michelle Lacey ◽  
Jane McBride ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Latent Membrane Protein ◽  
Interferon Response ◽  
Latent Membrane Protein 1 ◽  
Type I ◽  
Induced Expression ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT The Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) is a functional homologue of the tumor necrosis factor receptor family and contributes substantially to the oncogenic potential of EBV through activation of nuclear factor κB (NF-κB). MicroRNAs (miRNAs) are a class of small RNA molecules that are involved in the regulation of cellular processes such as growth, development, and apoptosis and have recently been linked to cancer phenotypes. Through miRNA microarray analysis, we demonstrate that LMP1 dysregulates the expression of several cellular miRNAs, including the most highly regulated of these, miR-146a. Quantitative reverse transcription-PCR analysis confirmed induced expression of miR-146a by LMP1. Analysis of miR-146a expression in EBV latency type III and type I cell lines revealed substantial expression of miR-146a in type III (which express LMP1) but not in type I cell lines. Reporter studies demonstrated that LMP1 induces miR-146a predominantly through two NF-κB binding sites in the miR-146a promoter and identified a role for an Oct-1 site in conferring basal and induced expression. Array analysis of cellular mRNAs expressed in Akata cells transduced with an miR-146a-expressing retrovirus identified genes that are directly or indirectly regulated by miR-146a, including a group of interferon-responsive genes that are inhibited by miR-146a. Since miR-146a is known to be induced by agents that activate the interferon response pathway (including LMP1), these results suggest that miR-146a functions in a negative feedback loop to modulate the intensity and/or duration of the interferon response.

scholarly journals Epstein-Barr Virus Latent Membrane Protein 1 Induces Synthesis of Hypoxia-Inducible Factor 1α

2004 ◽  
Vol 24 (12) ◽  
pp. 5223-5234 ◽  
Author(s):  
Naohiro Wakisaka ◽  
Satoru Kondo ◽  
Tomokazu Yoshizaki ◽  
Shigeyuki Murono ◽  
Mitsuru Furukawa ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Hypoxia Inducible Factor ◽  
Latent Membrane Protein ◽  
Mitogen Activated Protein Kinase ◽  
Latent Membrane Protein 1 ◽  
Epithelial Cell Line ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric basic helix-loop-helix transcription factor composed of HIF-1α and HIF-1β that is the central regulator of responses to hypoxia. The specific binding of HIF-1 to the hypoxia-responsive element (HRE) induces the transcription of genes that respond to hypoxic conditions, including vascular endothelial growth factor (VEGF). Here we report that expression of HIF-1α is increased in diverse Epstein-Barr virus (EBV)-infected type II and III cell lines, which express EBV latent membrane protein 1 (LMP1), the principal EBV oncoprotein, as well as other latency proteins, but not in the parental EBV-negative cell lines. We show first that transfection of an LMP1 expression plasmid into Ad-AH cells, an EBV-negative nasopharyngeal epithelial cell line, induces synthesis of HIF-1α protein without increasing its stability or mRNA level. The mitogen-activated protein kinase (MAPK) kinase inhibitor PD98059 markedly reduces induction of HIF-1α by LMP1. Catalase, an H2O2 scavenger, strongly suppresses LMP1-induced production of H2O2, which results in a decrease in the expression of HIF-1α induced by LMP1. Inhibition of the NF-κB, c-jun N-terminal kinase, p38 MAPK, and phosphatidylinositol 3-kinase pathways did not affect HIF-1α expression. Moreover, LMP1 induces HIF-1 DNA binding activity and upregulates HRE and VEGF promoter transcriptional activity. Finally, LMP1 increases the appearance of VEGF protein in extracellular fluids; induction of VEGF is suppressed by PD98059 or catalase. These results suggest that LMP1 increases HIF-1 activity through induction of HIF-1α protein expression, which is controlled by p42/p44 MAPK activity and H2O2. The ability of EBV, and specifically its major oncoprotein, LMP1, to induce HIF-1α along with other invasiveness and angiogenic factors reported previously discloses additional oncogenic properties of this tumor virus.

CD99 expression is positively regulated by Sp1 and is negatively regulated by Epstein-Barr virus latent membrane protein 1 through nuclear factor-κB

Blood ◽  
2001 ◽  
Vol 97 (11) ◽  
pp. 3596-3604 ◽  
Author(s):  
Im-soon Lee ◽  
Min Kyung Kim ◽  
Eun Young Choi ◽  
Anja Mehl ◽  
Kyeong Cheon Jung ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Promoter Region ◽  
Promoter Activity ◽  
Epstein Barr Virus ◽  
Latent Membrane Protein ◽  
Hodgkin Disease ◽  
Latent Membrane Protein 1 ◽  
Nuclear Factor ◽  
Barr Virus ◽  
Epstein Barr

Epstein-Barr virus (EBV)–encoded latent membrane protein-1 (LMP1) is highly expressed in Hodgkin and Reed-Sternberg (H-RS) cells from patients with EBV-associated Hodgkin disease. It was previously demonstrated that CD99 can be negatively regulated by LMP1 at the transcriptional level, and the decreased expression of CD99 in a B lymphocyte cell line generates H-RS–like cells. In this study, detailed dissection of the CD99 promoter region was performed to search regulatory factor(s) involved in the expression of the gene. Using various mutant constructs containing deletions in the promoter region, it was revealed that the maximal promoter activity was retained on 5′-deletion to the position −137 from the transcriptional initiation site. Despite the presence of multiple putative Sp1-binding sites in the promoter region, the site located at −95 contributes heavily as a positive cis-acting element to its basal promoter activity. However, on examination of the involvement of the positive-acting Sp1-binding site of the promoter for the repressive activity of LMP1, it appeared to be dispensable. Instead, the repressive effect was mapped to the nuclear factor (NF)-κB activation domains in the cytoplasmic carboxyl terminus of LMP1 despite the absence of the NF-κB consensus sequences in the CD99 promoter region. Furthermore, the decreased CD99 promoter activity by LMP1 was markedly restored when NF-κB activity was inhibited. Taken together, these data suggest that Sp1 activates, whereas LMP1 represses, transcription from the CD99 promoter through the NF-κB signaling pathway, and they might aid in the understanding of the molecular mechanisms of viral pathogenesis in EBV-positive Hodgkin disease.

scholarly journals MUC1 Induced by Epstein-Barr Virus Latent Membrane Protein 1 Causes Dissociation of the Cell-Matrix Interaction and Cellular Invasiveness via STAT Signaling

2006 ◽  
Vol 81 (4) ◽  
pp. 1554-1562 ◽  
Author(s):  
Satoru Kondo ◽  
Tomokazu Yoshizaki ◽  
Naohiro Wakisaka ◽  
Toshiyuki Horikawa ◽  
Shigeyuki Murono ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Membrane Protein ◽  
Tumor Cells ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Latent Membrane Protein ◽  
Latent Membrane Protein 1 ◽  
Barr Virus ◽  
Epstein Barr ◽  
Cellular Invasiveness

ABSTRACT Disruption of cellular adhesion is an essential pathobiologic step leading to tumor dissemination. Mucin 1 (MUC1) is a mucinous glycoprotein expressed at the surfaces of epithelial cells in many tissues and their carcinomas. MUC1 plays crucial roles in tumor invasion and metastasis, especially in opposing cell adhesion. We have shown that virus infection, specifically by the human tumor virus Epstein-Barr virus (EBV) induces a spectrum of cellular invasiveness and metastasis factors. Here we show that expression of MUC1 is increased in diverse latently EBV-infected cell lines that express latent membrane protein 1 (LMP1), the main viral oncoprotein, and that the level of MUC1 was suppressed by expression of a dominant-negative mutant of LMP1. Expression of LMP1 in EBV-negative nasopharyngeal cell lines induces expression of MUC1 through activation of the MUC1 promoter via binding of STAT1 and STAT3. Finally, LMP1 reduces cell adhesion ability, which is restored by inhibition of MUC1 expression with MUC1 small interfering RNA (siRNA). In addition, LMP1 increases cell invasiveness, which is suppressed by MUC1 siRNA. Thus, LMP1 induces MUC1, a factor important in an early step of detachment and release of tumor cells, which along with induction of other invasiveness and angiogenic factors may combine to act in a complex sequential process that culminates in metastasis of EBV-infected tumor cells.

Sign in / Sign up

Export Citation Format

Share Document