Limits...
PRIMA-1MET induces nucleolar translocation of Epstein-Barr virus-encoded EBNA-5 protein.

Stuber G, Flaberg E, Petranyi G, Otvös R, Rökaeus N, Kashuba E, Wiman KG, Klein G, Szekely L - Mol. Cancer (2009)

Bottom Line: The process is reversible since the aggregates are dissolved upon removal of PRIMA-1MET.Our results suggest that mutant p53 is not the sole target of PRIMA-1MET.We propose that PRIMA-1MET may reversibly inhibit cellular chaperons that prevent the aggregation of misfolded proteins, and that EBNA-5 may serve as a surrogate drug target for elucidating the precise molecular action of PRIMA-1MET.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institute, Stockholm, Sweden. Gyorgy.Stuber@ki.se

ABSTRACT
The low molecular weight compound, PRIMA-1MET restores the transcriptional transactivation function of certain p53 mutants in tumor cells. We have previously shown that PRIMA-1MET induces nucleolar translocation of p53, PML, CBP and Hsp70. The Epstein-Barr virus encoded, latency associated antigen EBNA-5 (also known as EBNA-LP) is required for the efficient transformation of human B lymphocytes by EBV. EBNA-5 associates with p53-hMDM2-p14ARF complexes. EBNA-5 is a nuclear protein that translocates to the nucleolus upon heat shock or inhibition of proteasomes along with p53, hMDM2, Hsp70, PML and proteasome subunits. Here we show that PRIMA-1MET induces the nucleolar translocation of EBNA-5 in EBV transformed B lymphoblasts and in transfected tumor cells. The PRIMA-1MET induced translocation of EBNA-5 is not dependent on the presence of mutant p53. It also occurs in p53 cells or in cells that express wild type p53. Both the native and the EGFP or DSRed conjugated EBNA-5 respond to PRIMA-1MET treatment in the same way. Image analysis of DSRed-EBNA-5 expressing cells, using confocal fluorescence time-lapse microscopy showed that the nucleolar translocation requires several hours to complete. FRAP (fluorescence recovery after photobleaching) and FLIP (fluorescence loss in photobleaching) measurements on live cells showed that the nucleolar translocation was accompanied by the formation of EBNA-5 aggregates. The process is reversible since the aggregates are dissolved upon removal of PRIMA-1MET. Our results suggest that mutant p53 is not the sole target of PRIMA-1MET. We propose that PRIMA-1MET may reversibly inhibit cellular chaperons that prevent the aggregation of misfolded proteins, and that EBNA-5 may serve as a surrogate drug target for elucidating the precise molecular action of PRIMA-1MET.

Show MeSH

Related in: MedlinePlus

Distribution of DSRed-EBNA-5 in the nucleus of a living MCF7 cell that carries wild type p53. Single confocal section selected from the middle of a series of 21 images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2667484&req=5

Figure 3: Distribution of DSRed-EBNA-5 in the nucleus of a living MCF7 cell that carries wild type p53. Single confocal section selected from the middle of a series of 21 images.

Mentions: In untreated, transfected cells EBNA-5 localized to the low DNA density areas corresponding to the euchromatin (Figure 3). It was either absent from the nucleolus or if present its level did not exceed the amount in the nucleoplasm (Additional file 1 and additional file 2). In the treated cells there was an overall increase of EBNA-5 levels with a very prominent increase in the nucleolus. After 20 hours of treatment almost all diffuse nucleoplasmic EBNA-5 signal was concentrated in numerous distinct foci evenly distributed throughout the entire nucleus.


PRIMA-1MET induces nucleolar translocation of Epstein-Barr virus-encoded EBNA-5 protein.

Stuber G, Flaberg E, Petranyi G, Otvös R, Rökaeus N, Kashuba E, Wiman KG, Klein G, Szekely L - Mol. Cancer (2009)

Distribution of DSRed-EBNA-5 in the nucleus of a living MCF7 cell that carries wild type p53. Single confocal section selected from the middle of a series of 21 images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2667484&req=5

Figure 3: Distribution of DSRed-EBNA-5 in the nucleus of a living MCF7 cell that carries wild type p53. Single confocal section selected from the middle of a series of 21 images.
Mentions: In untreated, transfected cells EBNA-5 localized to the low DNA density areas corresponding to the euchromatin (Figure 3). It was either absent from the nucleolus or if present its level did not exceed the amount in the nucleoplasm (Additional file 1 and additional file 2). In the treated cells there was an overall increase of EBNA-5 levels with a very prominent increase in the nucleolus. After 20 hours of treatment almost all diffuse nucleoplasmic EBNA-5 signal was concentrated in numerous distinct foci evenly distributed throughout the entire nucleus.

Bottom Line: The process is reversible since the aggregates are dissolved upon removal of PRIMA-1MET.Our results suggest that mutant p53 is not the sole target of PRIMA-1MET.We propose that PRIMA-1MET may reversibly inhibit cellular chaperons that prevent the aggregation of misfolded proteins, and that EBNA-5 may serve as a surrogate drug target for elucidating the precise molecular action of PRIMA-1MET.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institute, Stockholm, Sweden. Gyorgy.Stuber@ki.se

ABSTRACT
The low molecular weight compound, PRIMA-1MET restores the transcriptional transactivation function of certain p53 mutants in tumor cells. We have previously shown that PRIMA-1MET induces nucleolar translocation of p53, PML, CBP and Hsp70. The Epstein-Barr virus encoded, latency associated antigen EBNA-5 (also known as EBNA-LP) is required for the efficient transformation of human B lymphocytes by EBV. EBNA-5 associates with p53-hMDM2-p14ARF complexes. EBNA-5 is a nuclear protein that translocates to the nucleolus upon heat shock or inhibition of proteasomes along with p53, hMDM2, Hsp70, PML and proteasome subunits. Here we show that PRIMA-1MET induces the nucleolar translocation of EBNA-5 in EBV transformed B lymphoblasts and in transfected tumor cells. The PRIMA-1MET induced translocation of EBNA-5 is not dependent on the presence of mutant p53. It also occurs in p53 cells or in cells that express wild type p53. Both the native and the EGFP or DSRed conjugated EBNA-5 respond to PRIMA-1MET treatment in the same way. Image analysis of DSRed-EBNA-5 expressing cells, using confocal fluorescence time-lapse microscopy showed that the nucleolar translocation requires several hours to complete. FRAP (fluorescence recovery after photobleaching) and FLIP (fluorescence loss in photobleaching) measurements on live cells showed that the nucleolar translocation was accompanied by the formation of EBNA-5 aggregates. The process is reversible since the aggregates are dissolved upon removal of PRIMA-1MET. Our results suggest that mutant p53 is not the sole target of PRIMA-1MET. We propose that PRIMA-1MET may reversibly inhibit cellular chaperons that prevent the aggregation of misfolded proteins, and that EBNA-5 may serve as a surrogate drug target for elucidating the precise molecular action of PRIMA-1MET.

Show MeSH
Related in: MedlinePlus