An Evaluation of the Contribution of EBNA1 Expression to Transgenic Mouse Lymphomagenesis

Tsimbouri, P. , Al-Sheikh, Y., Mclean, A., Drotar, M. and Wilson, J. B. (2006) An Evaluation of the Contribution of EBNA1 Expression to Transgenic Mouse Lymphomagenesis. 12th International EBV Symposium, Boston, MA, USA, 08-12 Jul 2006.

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Abstract

Background: There is growing evidence that EBNA-1 can influence B-cell survival, but whether this is sufficient to predispose transgenic mice to lymphomagenesis is controversial. We have previously shown that two out of 12 established transgenic mouse lines generated using an EµEBNA-1 transgene expressed EBNA-1 (Wilson et al., 1996, EMBO J., 15, p3117). First, this demonstrated that in vivo expression of full length EBNA-1 from a relatively simple transgene is not efficient. Second, mice of the two expressing lines succumb to B-cell lymphoma with identical pathology, but with dramatically different penetrance and latency to onset, essentially a fast tumour line (line 26) and a slow tumour line (line 59). A further development from the “fast line” was that a spontaneous partial transgene deletion arose, giving rise to a sub-line of mice (designated 26A), which no longer showed EBNA-1 expression or developed lymphoma. Methods: In order to explore the contribution of EBNA-1 to the phenotype and to examine if there is any influence from cellular sequences at the sites of transgene insertion, we have taken three approaches: [1] To explore the phenotype of lymphocytes from both transgenic lines, prior to tumour development, where any characteristic in common between the two lines must result from EBNA-1 expression; [2] To use dominant negative EBNA-1 expression to examine the effect of EBNA-1 “withdrawal”; [3] To identify and characterise the transgene insertion sites. Results: [1] Lymphocytes explanted and cultured from mice of both transgenic lines initially show enhanced proliferation and then prolonged survival compared to non-transgenic wild-type sibling controls. This property is only evident when the cells are cultured in the presence of interleukin-2 (IL-2). [2] Transfection and expression of dominant negative forms of EBNA-1 in a cell line derived from an EBNA-1 expressing line 59 tumour (co-expressing LMP1) is not compatible with the survival of these cells, while expression in cell lines derived from LMP1-only tumours is innocuous. [3] The transgene insertion site for line 59 has been precisely mapped to murine chromosome 4 band D3. No known oncogenes lie withing a Mb region encompassing the transgene. The transgene insertion site for sub-line 26A has been precisely mapped to murine chromosome 3 band H2. No known oncogenes lie within a Mb region encompassing the transgene. The transgene insertion site for line 26 has been mapped to murine chromosome 5 band B and fine mapping is ongoing. Conclusion: EBNA-1 promotes lymphocyte survival in the transgenic system.

Item Type:Conference or Workshop Item
Status:Published
Refereed:No
Glasgow Author(s) Enlighten ID:Tsimbouri, Dr Monica and Wilson, Professor Joanna and Drotar, Mr Mark
Authors: Tsimbouri, P., Al-Sheikh, Y., Mclean, A., Drotar, M., and Wilson, J. B.
Subjects:Q Science > QR Microbiology > QR355 Virology
College/School:College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
College of Medical Veterinary and Life Sciences > School of Life Sciences
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