Intranuclear localization of the transcription coadaptor CBP/p300 and the transcription factor RBP-Jk in relation to EBNA-2 and-5 in B lymphocytes

We have studied the expression and the localization of the cellular protein s CBP/p300 and RBP-Jk in in vitro EBV-infected human B lymphocytes in relat ion to the EBNA-2 and EBNA-5 proteins. We found that the level of CBP/p300 was elevated drastically by EBV infection and also after activation by CD40 ligation. Thus the increase in CBP/p300 expression in the EBV-infected cel ls is related to the virus-induced activation and proliferation of the cell s. EBNA-2 and RBP-Jk colocalized in the nucleoplasm, which is in accordance with their functional interaction. We confirmed earlier reports about the presence and colocalization of EBNA-5 and CBP in the nuclear POD bodies. On the other hand, neither EBNA-2 nor p300 was detected in the PODS. The expr ession of these two proteins overlapped in some distinct dots of the nucleo plasm. Taken together, the different patterns of CBP and p300 expression an d their different localization in relation to the PML bodies and two EBV-en coded proteins in the B cells may provide some clue to their distinct funct ional roles. (C) 2001 Academic Press.