Nuclear compartmentalization of viral and cellular proteins involved in gamma-herpes virus (EBV and HHV-8) mediated cellular transformation
Author: Mattsson, Karin
Date: 2003-11-28
Location: Föreläsningssalen, Mikrobiologiskt och Tumörbiologiskt Centrum (MTC), Theorells väg 1, Karolinska Institutet
Time: 13.00
Department: Mikrobiologiskt och Tumörbiologiskt Centrum (MTC) / Microbiology and Tumor Biology Center (MTC)
Abstract
The aim of the work described in this thesis has been to characterize the nuclear compartmentalization of cellular and viral proteins involved in EBV or HHV-8 mediated cellular transformation. We have studied the EBV encoded EBNA-5 and its association with the PML nuclear bodies (NBs) and nuclear inclusions. We showed that in EBV infected cells the EBNA-5 protein accumulated in NBs. The NBs accumulates a number of cellular proteins, including the PML protein (promyelocytic leukemia protein) and are targeted by various viral proteins. In acute promyelocytic leukemia the NBs are disrupted. Several recent findings indicate that the NBs are involved in proteasomal protein degradation.
We wanted to study a possible involvement of the NBs and its component EBNA-5 in the proteasomal protein degradation. We found that inhibition of the proteasomal-protein degradation machinery induced a coordinated change in localization and the translocation of both endogenous and transfected EBNA-5 along with Hsp70 and mutant p53 to the nucleoli. This may reflect the involvement of EBNA-5 in the regulation of intracellular protein trafficking, possibly associated with the proteasome-mediated degradation. The suggested association of PML protein and NBs with proteasome-mediated protein degradation prompted us to analyze the intracellular distribution of proteasomes, different NB components and non-NB associated proteins in the presence of a proteasome inhibitor.
Inhibition of the proteasomes in different cell lines resulted in a radical redistribution of the NB-associated proteins PML, Sp100, SUMO-1 and EBNA-5 along with the proteasomes themselves. The accumulation of NB-associated proteins and proteasomes in the nucleoli of MG132-treated cells indicates that these proteins may target the nucleoli under normal conditions and that the nucleolus may have a function in the regulation of proteasomal protein degradation. EBNA-5 interacts with the p14ARF protein, a regulator of the p53 pathway.
We have shown that in the presence of EBNA-5, the p14ARF localized to the nucleoli but also in extra-nucleolar inclusions. In addition, the inclusions contained p53 and HDM2, and were surrounded by NBs and proteasomes. p14ARF was shown to induce the relocation of HDM2 and p53 to these extranucleolar sites. Accumulation of PML and proteasomes at these sites suggest that the components of the nuclear inclusions are targeted for proteasome-mediated degradation. We have also studied the influence of HHV-8 encoded latency associated nuclear antigen (LANA-1) on heterochromatin. LANA-1 is the major latency associated nuclear protein of HHV-8. HHV-8 is a newly identified human herpes virus that is the likely causative agent of Kaposis sarcoma. The virus is also present in body cavity lymphomas and in multi-centric Castleman's disease.
We have shown that LANA1 accumulates in heterochromatin-associated nuclear bodies and stays on the mitotic chromosomes during cell division. We showed that LANA-1 induces the expression of its cellular partner RING3, a human homologue of the Drosophila female sterile homeotic (fsh) gene. LANA-1 relocates RING3 from the euchromatin to the heterochromatin borders. High levels of exogenously expressed LANA-1 caused a re-organization of heterochromatin in both human and mouse cells. Our recent results demonstrate that it is the internal acidic repeat of LANA-1 that is responsible for the re-organization of heterochromatin. We could also show that LANA-1 change the organization of heterochromatin-associated proteins such as histone H3 (trimethyl K9) and MeCP2 in parallel with the re-organization of heterochromatin. We suggest that LANA may create a local euchromatic microenvironment around the viral episomes that are anchored to the heterochromatin.
We wanted to study a possible involvement of the NBs and its component EBNA-5 in the proteasomal protein degradation. We found that inhibition of the proteasomal-protein degradation machinery induced a coordinated change in localization and the translocation of both endogenous and transfected EBNA-5 along with Hsp70 and mutant p53 to the nucleoli. This may reflect the involvement of EBNA-5 in the regulation of intracellular protein trafficking, possibly associated with the proteasome-mediated degradation. The suggested association of PML protein and NBs with proteasome-mediated protein degradation prompted us to analyze the intracellular distribution of proteasomes, different NB components and non-NB associated proteins in the presence of a proteasome inhibitor.
Inhibition of the proteasomes in different cell lines resulted in a radical redistribution of the NB-associated proteins PML, Sp100, SUMO-1 and EBNA-5 along with the proteasomes themselves. The accumulation of NB-associated proteins and proteasomes in the nucleoli of MG132-treated cells indicates that these proteins may target the nucleoli under normal conditions and that the nucleolus may have a function in the regulation of proteasomal protein degradation. EBNA-5 interacts with the p14ARF protein, a regulator of the p53 pathway.
We have shown that in the presence of EBNA-5, the p14ARF localized to the nucleoli but also in extra-nucleolar inclusions. In addition, the inclusions contained p53 and HDM2, and were surrounded by NBs and proteasomes. p14ARF was shown to induce the relocation of HDM2 and p53 to these extranucleolar sites. Accumulation of PML and proteasomes at these sites suggest that the components of the nuclear inclusions are targeted for proteasome-mediated degradation. We have also studied the influence of HHV-8 encoded latency associated nuclear antigen (LANA-1) on heterochromatin. LANA-1 is the major latency associated nuclear protein of HHV-8. HHV-8 is a newly identified human herpes virus that is the likely causative agent of Kaposis sarcoma. The virus is also present in body cavity lymphomas and in multi-centric Castleman's disease.
We have shown that LANA1 accumulates in heterochromatin-associated nuclear bodies and stays on the mitotic chromosomes during cell division. We showed that LANA-1 induces the expression of its cellular partner RING3, a human homologue of the Drosophila female sterile homeotic (fsh) gene. LANA-1 relocates RING3 from the euchromatin to the heterochromatin borders. High levels of exogenously expressed LANA-1 caused a re-organization of heterochromatin in both human and mouse cells. Our recent results demonstrate that it is the internal acidic repeat of LANA-1 that is responsible for the re-organization of heterochromatin. We could also show that LANA-1 change the organization of heterochromatin-associated proteins such as histone H3 (trimethyl K9) and MeCP2 in parallel with the re-organization of heterochromatin. We suggest that LANA may create a local euchromatic microenvironment around the viral episomes that are anchored to the heterochromatin.
List of papers:
I. Pokrovskaja K, Mattsson K, Kashuba E, Klein G, Szekely L (2001). Proteasome inhibitor induces nucleolar translocation of Epstein-Barr virus-encoded EBNA-5. J Gen Virol. 82(Pt 2): 345-58.
Pubmed
II. Mattsson K, Pokrovskaja K, Kiss C, Klein G, Szekely L (2001). Proteins associated with the promyelocytic leukemia gene product (PML)-containing nuclear body move to the nucleolus upon inhibition of proteasome-dependent protein degradation. Proc Natl Acad Sci U S A. 98(3): 1012-7. Epub 2001 Jan 23
Pubmed
III. Kashuba E, Mattsson K, Klein G, Szekely L (2003). p14ARF induces the relocation of HDM2 and p53 to extranucleolar sites that are targeted by PML bodies and proteasomes. Mol Cancer. 2(1): 18. Epub 2003 Mar 05
Pubmed
IV. Kashuba E, Mattsson K, Pokrovskaja K, Kiss C, Protopopova M, Ehlin-Henriksson B, Klein G, Szekely L (2003). EBV-encoded EBNA-5 associates with P14ARF in extranucleolar inclusions and prolongs the survival of P14ARF-expressing cells. Int J Cancer. 105(5): 644-53.
Pubmed
V. Szekely L, Kiss C, Mattsson K, Kashuba E, Pokrovskaja K, Juhasz A, Holmvall P, Klein G (1999). Human herpesvirus-8-encoded LNA-1 accumulates in heterochromatin- associated nuclear bodies. J Gen Virol. 80(Pt 11): 2889-900.
Pubmed
VI. Mattsson K, Kiss C, Platt GM, Simpson GR, Kashuba E, Klein G, Schulz TF, Szekely L (2002). Latent nuclear antigen of Kaposis sarcoma herpesvirus/human herpesvirus-8 induces and relocates RING3 to nuclear heterochromatin regions. J Gen Virol. 83(Pt 1): 179-88.
Pubmed
VII. Mattsson K, Kathi E, Klein G, Schulz TF, Szekely L (2003). HHV-8 encoded latent nuclear antigen LANA-1 alters the organization of cellular heterochromatin. [Manuscript]
I. Pokrovskaja K, Mattsson K, Kashuba E, Klein G, Szekely L (2001). Proteasome inhibitor induces nucleolar translocation of Epstein-Barr virus-encoded EBNA-5. J Gen Virol. 82(Pt 2): 345-58.
Pubmed
II. Mattsson K, Pokrovskaja K, Kiss C, Klein G, Szekely L (2001). Proteins associated with the promyelocytic leukemia gene product (PML)-containing nuclear body move to the nucleolus upon inhibition of proteasome-dependent protein degradation. Proc Natl Acad Sci U S A. 98(3): 1012-7. Epub 2001 Jan 23
Pubmed
III. Kashuba E, Mattsson K, Klein G, Szekely L (2003). p14ARF induces the relocation of HDM2 and p53 to extranucleolar sites that are targeted by PML bodies and proteasomes. Mol Cancer. 2(1): 18. Epub 2003 Mar 05
Pubmed
IV. Kashuba E, Mattsson K, Pokrovskaja K, Kiss C, Protopopova M, Ehlin-Henriksson B, Klein G, Szekely L (2003). EBV-encoded EBNA-5 associates with P14ARF in extranucleolar inclusions and prolongs the survival of P14ARF-expressing cells. Int J Cancer. 105(5): 644-53.
Pubmed
V. Szekely L, Kiss C, Mattsson K, Kashuba E, Pokrovskaja K, Juhasz A, Holmvall P, Klein G (1999). Human herpesvirus-8-encoded LNA-1 accumulates in heterochromatin- associated nuclear bodies. J Gen Virol. 80(Pt 11): 2889-900.
Pubmed
VI. Mattsson K, Kiss C, Platt GM, Simpson GR, Kashuba E, Klein G, Schulz TF, Szekely L (2002). Latent nuclear antigen of Kaposis sarcoma herpesvirus/human herpesvirus-8 induces and relocates RING3 to nuclear heterochromatin regions. J Gen Virol. 83(Pt 1): 179-88.
Pubmed
VII. Mattsson K, Kathi E, Klein G, Schulz TF, Szekely L (2003). HHV-8 encoded latent nuclear antigen LANA-1 alters the organization of cellular heterochromatin. [Manuscript]
Issue date: 2003-11-07
Publication year: 2003
ISBN: 91-7349-717-7
Statistics
Total Visits
Views | |
---|---|
Nuclear ...(legacy) | 273 |
Nuclear ... | 83 |
Total Visits Per Month
November 2023 | December 2023 | January 2024 | February 2024 | March 2024 | April 2024 | May 2024 | |
---|---|---|---|---|---|---|---|
Nuclear ... | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
Top country views
Views | |
---|---|
United States | 49 |
Germany | 38 |
China | 37 |
Sweden | 32 |
South Korea | 10 |
France | 7 |
Finland | 6 |
Greece | 6 |
Ireland | 6 |
Japan | 4 |
Top cities views
Views | |
---|---|
Kiez | 15 |
Sunnyvale | 11 |
Beijing | 10 |
Seoul | 10 |
Athens | 6 |
Dublin | 6 |
Tianjin | 6 |
Shenzhen | 5 |
Ashburn | 4 |
Ballerup | 3 |