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Animal: DNA Viruses |
Queensland Institute of Medical Research and University of Queensland Joint Oncology Program, 300 Herston Road, Herston 4029, Brisbane, Australia1
Author for correspondence: Kenia Krauer. Fax +61 7 3362 0106. e-mail keniaK{at}qimr.edu.au
RBP, a transcriptional repressor, is intricately involved in EpsteinBarr virus (EBV) transformation of human B cells. The EBV nuclear proteins EBNA-2, -3, -4 and -6 all utilize RBP to regulate the transcription of both cellular and viral genes. This study investigates the isoforms of the RBP protein in Burkitts lymphoma (BL) cells and in EBV-transformed lymphoblastoid cell lines (LCLs). Two-dimensional gel electrophoresis showed the presence of two different cellular isoforms of RBP; the molecular masses and isoelectric points of these two isoforms corresponded to RBP-J
and RBP-2N. Fractionation studies and green fluorescent protein (GFP)-tagged expression studies demonstrated that both RBP isoforms were located predominantly in the cell nucleus. Interestingly, GFP-tagged RBP-J
showed diffuse, uniform nuclear staining, whereas GFP-tagged RBP-2N showed a discrete nuclear pattern, demonstrating differences between the two isoforms. Within the nuclear fraction of EBV-negative BL cells, RBP existed both in a free form and bound to chromatin, whereas in LCLs the intranuclear RBP was predominantly chromatin-bound. Expression of the EBV latent proteins was found to lead to the sequestering of RBP from the cytoplasm into the cell nucleus and to an increase in the chromatin-bound forms of RBP.
This article has been cited by other articles:
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P. P. Singh, B. Voleti, and A. Agrawal A Novel RBP-J{kappa}-Dependent Switch from C/EBPbeta to C/EBP{zeta} at the C/EBP Binding Site on the C-Reactive Protein Promoter J. Immunol., June 1, 2007; 178(11): 7302 - 7309. [Abstract] [Full Text] [PDF] |
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