Reversible nucleolar translocation of Epstein-Barr virus-encoded EBNA-5 and hsp70 proteins after exposure to heat shock or cell density congestion.
The Epstein-Barr virus (EBV)-encoded, nuclear matrix-associated EBNA-5 protein is preferentially localized within distinct nuclear blobs in EBV-immortalized lymphoblastoid cell lines. We have previously found that the same blobs also contain retinoblastoma (Rb) protein. We now show that they contain hsp70 protein as well. Both EBNA-5 and hsp70 translocate to the nucleolus under cell density congestion or after heat shock. Both proteins relocate to their original position upon the re-establishment of normal physiological conditions. EBNA-5 is tightly bound to the nuclear matrix. The translocated EBNA-5 is also tightly associated with matrix structures, as shown by sequential elution-based cell fractionation. The Rb protein does not translocate to the nucleolus. The virally encoded EBNA-1, -2, -3 and -6, and cellular PCNA, snRNP and cyclin E are not affected either. The translocation of EBNA-5 to the nucleolus is not species- or cell type-specific since stress conditions induced the same phenomenon in EBNA-5-transfected human, mouse and rat cells of different tissue origins.
Szekely
L
L
Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, Sweden.
Jiang
W Q
WQ
Pokrovskaja
K
K
Wiman
K G
KG
Klein
G
G
Ringertz
N
N
D000818:Animals; D000956:Antigens, Viral / Q000378:metabolism*; D001402:B-Lymphocytes / Q000821:virology; D002452:Cell Count; D002461:Cell Line, Transformed; D002466:Cell Nucleolus / Q000378:metabolism* / Q000821:virology*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019309:Epstein-Barr Virus Nuclear Antigens; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D018869:Heat-Shock Response; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D006801:Humans; D051379:Mice; D015530:Nuclear Matrix / Q000821:virology; D051381:Rats; D013045:Species Specificity; D014407:Tumor Cells, Cultured
D000956:Antigens, Viral; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D018840:HSP70 Heat-Shock Proteins