EBV-encoded EBNA-5 associates with P14ARF in extranucleolar inclusions and prolongs the survival of P14ARF-expressing cells.
Epstein-Barr virus (EBV) carrying lymphoblastoid cells of normal origin express the full program of all 9 virus-encoded, growth transformation associated proteins. They have an intact p53 pathway as a rule. This raises the question of whether any of the viral proteins impair the pathway functionally. Using a yeast 2-hybrid system, we have shown that EBNA-5 but not the other EBNAs interacts with the p14ARF protein, a regulator of the p53 pathway. The interaction was confirmed in vitro using a GST pull-down assay. Moreover, expression of EBNA-5 increased the survival of p14ARF-transfected cells. EBV infection of resting B cells induced the expression of p14ARF mRNA without increased level of the protein. A fraction of the p14ARF localized to the nucleoli but the bulk of the protein accumulated in nuclear but extranucleolar inclusions. Formation of the extranucleolar inclusions led to complete relocalization of EBNA-5 from nucleoplasm to these structures. The inclusions also contained p53 and HDM2, and were surrounded by PML bodies and proteasomes, which suggests that these inclusions could be targets for proteasome dependent protein degradation.
Microbiology and Tumor Biology Center (MTC), Karolinska Institute, Nobels vag 16, Box 280, S-171 77 Stockholm, Sweden. elena.kashuba@mtc.ki.se
Elena
E
Kashuba
Karin
K
Mattsson
Katja
K
Pokrovskaja
Csaba
C
Kiss
Marina
M
Protopopova
Barbro
B
Ehlin-Henriksson
George
G
Klein
Laszlo
L
Szekely
D016475:3T3 Cells / Q000378:metabolism / Q000821:virology; D021581:Active Transport, Cell Nucleus; D000230:Adenocarcinoma / Q000473:pathology; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology*; D001859:Bone Neoplasms / Q000473:pathology; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D002470:Cell Survival; D002472:Cell Transformation, Viral / Q000502:physiology; D003110:Colonic Neoplasms / Q000473:pathology; D003546:Cysteine Endopeptidases / Q000378:metabolism; D019309:Epstein-Barr Virus Nuclear Antigens / Q000502:physiology*; D015967:Gene Expression Regulation, Viral; D006367:HeLa Cells / Q000378:metabolism / Q000821:virology; D004854:Herpesvirus 4, Human / Q000502:physiology*; D006801:Humans; D051379:Mice; D009097:Multienzyme Complexes / Q000378:metabolism; D009687:Nuclear Proteins; D012516:Osteosarcoma / Q000473:pathology; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000821:virology; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D020798:Two-Hybrid System Techniques
C421621:EBNA-5 protein, Epstein-Barr virus; D019309:Epstein-Barr Virus Nuclear Antigens; D009097:Multienzyme Complexes; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex