Mutational Analysis of the Transforming Function of the EBV Encoded LMP-1

Moorthy, Ramkumar; Thorley‐Lawson, David A.

doi:10.1007/978-3-642-77633-5_46

Cited by 14 publications

(25 citation statements)

References 7 publications

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“…For immunostaining analyses, cells grown to confluence on cover-slips were fixed with methanol for 10 min at Ϫ20°C, blocked with BSA for 1 h, and incubated with individual antibodies for 1 h. The antibodies used in these experiments were ␣-E-cadherin antibody (Transduction Laboratories, Lexington, KY), ␣-␥-catenin, ␣-tubulin (Santa Cruz Biotechnology), or anti-LMP1 antibody S12 (25). Next, cells were washed and incubated in FITC-conjugated secondary antibody and 4Ј,6-diamidin-2-phenylindol-dihydrochloride (DAPI) (Roche Diagnostics) for 1 h before examination under a microscope (AxioplanII, Zeiss).…”

Section: Real-time Reverse Transcription (Rt)-pcrmentioning

confidence: 99%

The Epstein–Barr virus oncogene product, latent membrane protein 1, induces the downregulation of E-cadherin gene expression via activation of DNA methyltransferases

Tsai

Tse

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

278

215

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The latent membrane protein (LMP1) of Epstein-Barr virus (EBV) is expressed in EBV-associated nasopharyngeal carcinoma, which is notoriously metastatic. Although it is established that LMP1 represses E-cadherin expression and enhances the invasive ability of carcinoma cells, the mechanism underlying this repression remains to be elucidated. In this study, we demonstrate that LMP1 induces the expression and activity of the DNA methyltransferases 1, 3a, and 3b, using real-time reverse transcription-PCR and enzyme activity assay. This results in hypermethylation of the E-cadherin promoter and down-regulation of E-cadherin gene expression, as revealed by methylation-specific PCR, real-time reverse transcription-PCR and Western blotting data. The DNA methyltransferase inhibitor, 5-Aza-2dC, restores E-cadherin promoter activity and protein expression in LMP1-expressing cells, which in turn blocks cell migration ability, as demonstrated by the Transwell cell migration assay. Our findings suggest that LMP1 down-regulates E-cadherin gene expression and induces cell migration activity by using cellular DNA methylation machinery.

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Section: Real-time Reverse Transcription (Rt)-pcrmentioning

confidence: 99%

The Epstein–Barr virus oncogene product, latent membrane protein 1, induces the downregulation of E-cadherin gene expression via activation of DNA methyltransferases

Tsai

Tse

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

278

215

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show abstract

“…Relevant to this finding may be the observation that LMP-1 does not bind TRAF6, a RING domain ubiquitin ligase that, together with Ubc13/Uev1A, catalyses the synthesis of polyubiquitin chains linked through Lys63 (Deng et al, 2000). LMP-1 is a short-lived protein (Moorthy and Thorley-Lawson, 1990) and is degraded by ubiquitin-dependent proteolysis (Aviel et al, 2000). Interestingly, the single internal lysine residue of the B95.8 LMP-1 is not required for ubiquitination, while modification of the N-terminus results in full stabilizations, suggesting that this is the site of ubiquitin conjugation.…”

Section: The Growth Program: Lmp-1 a Viral Oncogene With An Unusual mentioning

confidence: 99%

Epstein–Barr virus oncogenesis and the ubiquitin–proteasome system

Masucci

2004

Oncogene

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Epstein-Barr virus (EBV), a human herpesvirus associated with lymphoid and epithelial cell tumors, encodes several proteins that exploit the ubiquitin-proteasome system to regulate latency and allow the persistence of infected cells in immunocompetent hosts. Further modifications of ubiquitin-dependent proteolysis by activated cellular oncogenes contribute to malignant transformation. A detailed understanding of these processes may lead to the development of new therapeutic strategies for EBVassociated cancers.

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“…Latent membrane protein 1 (LMP1) is considered the EBV oncogene as it can transform rodent fibroblast (Arrand et al, 1981;Wang et al, 1985;Moorthy and Thorley-Lawson, 1993), supports anchorage-independent growth in soft agar (Baichwal and Sugden, 1988), and when expressed in Rat-1 cells is tumorigenic in nude mice (Wang et al, 1985). With the exception of Burkitt's lymphoma, LMP1 is expressed in all EBV-associated human lymphoid malignancies.…”

Section: Introductionmentioning

confidence: 99%

LMP1 signaling and activation of NF-κB in LMP1 transgenic mice

et al. 2005

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Transgenic mice expressing Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) under the control of an immunoglobulin heavy-chain promoter and enhancer develop lymphoma at a threefold higher incidence than LMP1-negative mice. In vitro, LMP1 activates numerous signaling pathways including p38, c-Jun N terminal kinase (JNK), phosphatidylinositol 3 kinase (PI3K)/Akt, and NF-jB through interactions with tumor necrosis receptorassociated factors (TRAFs). These pathways are frequently activated in EBV-associated malignancies, although their activation cannot be definitively linked to LMP1 expression in vivo. In this study, interactions between LMP1 and TRAFs and the activation of PI3K/ Akt, JNK, p38, and NF-jB were examined in LMP1 transgenic mice. LMP1 co-immunoprecipitated with TRAFs 1, 2, and 3. Akt, JNK, and p38 were activated in LMP1-positive and -negative splenocytes as well as LMP1-positive and -negative lymphomas. Multiple forms of NF-jB were activated in healthy splenocytes from LMP1 transgenic mice, in contrast to healthy splenocytes from LMP1-negative mice. However, in both LMP1-positive and -negative lymphomas, only the oncogenic NF-jB c-Rel, was specifically activated. Similarly to EBV-associated malignancies, p53 protein was detected at high levels in the transgenic lymphomas, although mutations were not detected in the p53 gene. These data indicate that NF-jB is activated in LMP1-positive healthy splenocytes; however, NF-jB c-Rel is specifically activated in both the transgenic lymphomas and in the rare lymphomas that develop in negative mice. The LMP1-mediated activation of NF-jB may contribute to the specific activation of c-Rel and lead to the increased development of lymphoma in the LMP1 transgenic mice.

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Mutational Analysis of the Transforming Function of the EBV Encoded LMP-1

Cited by 14 publications

References 7 publications

The Epstein–Barr virus oncogene product, latent membrane protein 1, induces the downregulation of E-cadherin gene expression via activation of DNA methyltransferases

The Epstein–Barr virus oncogene product, latent membrane protein 1, induces the downregulation of E-cadherin gene expression via activation of DNA methyltransferases

Epstein–Barr virus oncogenesis and the ubiquitin–proteasome system

LMP1 signaling and activation of NF-κB in LMP1 transgenic mice

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