Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway.
Epstein-Barr virus (EBV) nuclear oncoprotein EBNA3C is essential for B-cell transformation and development of several B-cell lymphomas particularly those are generated in an immuno-compromised background. EBNA3C recruits ubiquitin-proteasome machinery for deregulating multiple cellular oncoproteins...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2020-02-01
|
| Series: | PLoS Pathogens |
| Online Access: | https://doi.org/10.1371/journal.ppat.1008105 |
| _version_ | 1798030210700935168 |
|---|---|
| author | Chandrima Gain Samaresh Malik Shaoni Bhattacharjee Arijit Ghosh Erle S Robertson Benu Brata Das Abhik Saha |
| author_facet | Chandrima Gain Samaresh Malik Shaoni Bhattacharjee Arijit Ghosh Erle S Robertson Benu Brata Das Abhik Saha |
| author_sort | Chandrima Gain |
| collection | DOAJ |
| description | Epstein-Barr virus (EBV) nuclear oncoprotein EBNA3C is essential for B-cell transformation and development of several B-cell lymphomas particularly those are generated in an immuno-compromised background. EBNA3C recruits ubiquitin-proteasome machinery for deregulating multiple cellular oncoproteins and tumor suppressor proteins. Although EBNA3C is found to be ubiquitinated at its N-terminal region and interacts with 20S proteasome, the viral protein is surprisingly stable in growing B-lymphocytes. EBNA3C can also circumvent autophagy-lysosomal mediated protein degradation and subsequent antigen presentation for T-cell recognition. Recently, we have shown that EBNA3C enhances autophagy, which serve as a prerequisite for B-cell survival particularly under growth deprivation conditions. We now demonstrate that proteasomal inhibition by MG132 induces EBNA3C degradation both in EBV transformed B-lymphocytes and ectopic-expression systems. Interestingly, MG132 treatment promotes degradation of two EBNA3 family oncoproteins-EBNA3A and EBNA3C, but not the viral tumor suppressor protein EBNA3B. EBNA3C degradation induced by proteasomal inhibition is partially blocked when autophagy-lysosomal pathway is inhibited. In response to proteasomal inhibition, EBNA3C is predominantly K63-linked polyubiquitinated, colocalized with the autophagy-lysosomal fraction in the cytoplasm and participated within p62-LC3B complex, which facilitates autophagy-mediated degradation. We further show that the degradation signal is present at the first 50 residues of the N-terminal region of EBNA3C. Proteasomal inhibition reduces the colony formation ability of this important viral oncoprotein, induces apoptotic cell death and increases transcriptional activation of both latent and lytic gene expression which further promotes viral reactivation from EBV transformed B-lymphocytes. Altogether, this study offers rationale to use proteasome inhibitors as potential therapeutic strategy against multiple EBV associated B-cell lymphomas, where EBNA3C is expressed. |
| first_indexed | 2024-04-11T19:36:32Z |
| format | Article |
| id | doaj.art-b33750fd9e56466d835db740a46ffee8 |
| institution | Directory Open Access Journal |
| issn | 1553-7366 1553-7374 |
| language | English |
| last_indexed | 2024-04-11T19:36:32Z |
| publishDate | 2020-02-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Pathogens |
| spelling | doaj.art-b33750fd9e56466d835db740a46ffee82022-12-22T04:06:50ZengPublic Library of Science (PLoS)PLoS Pathogens1553-73661553-73742020-02-01162e100810510.1371/journal.ppat.1008105Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway.Chandrima GainSamaresh MalikShaoni BhattacharjeeArijit GhoshErle S RobertsonBenu Brata DasAbhik SahaEpstein-Barr virus (EBV) nuclear oncoprotein EBNA3C is essential for B-cell transformation and development of several B-cell lymphomas particularly those are generated in an immuno-compromised background. EBNA3C recruits ubiquitin-proteasome machinery for deregulating multiple cellular oncoproteins and tumor suppressor proteins. Although EBNA3C is found to be ubiquitinated at its N-terminal region and interacts with 20S proteasome, the viral protein is surprisingly stable in growing B-lymphocytes. EBNA3C can also circumvent autophagy-lysosomal mediated protein degradation and subsequent antigen presentation for T-cell recognition. Recently, we have shown that EBNA3C enhances autophagy, which serve as a prerequisite for B-cell survival particularly under growth deprivation conditions. We now demonstrate that proteasomal inhibition by MG132 induces EBNA3C degradation both in EBV transformed B-lymphocytes and ectopic-expression systems. Interestingly, MG132 treatment promotes degradation of two EBNA3 family oncoproteins-EBNA3A and EBNA3C, but not the viral tumor suppressor protein EBNA3B. EBNA3C degradation induced by proteasomal inhibition is partially blocked when autophagy-lysosomal pathway is inhibited. In response to proteasomal inhibition, EBNA3C is predominantly K63-linked polyubiquitinated, colocalized with the autophagy-lysosomal fraction in the cytoplasm and participated within p62-LC3B complex, which facilitates autophagy-mediated degradation. We further show that the degradation signal is present at the first 50 residues of the N-terminal region of EBNA3C. Proteasomal inhibition reduces the colony formation ability of this important viral oncoprotein, induces apoptotic cell death and increases transcriptional activation of both latent and lytic gene expression which further promotes viral reactivation from EBV transformed B-lymphocytes. Altogether, this study offers rationale to use proteasome inhibitors as potential therapeutic strategy against multiple EBV associated B-cell lymphomas, where EBNA3C is expressed.https://doi.org/10.1371/journal.ppat.1008105 |
| spellingShingle | Chandrima Gain Samaresh Malik Shaoni Bhattacharjee Arijit Ghosh Erle S Robertson Benu Brata Das Abhik Saha Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway. PLoS Pathogens |
| title | Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway. |
| title_full | Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway. |
| title_fullStr | Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway. |
| title_full_unstemmed | Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway. |
| title_short | Proteasomal inhibition triggers viral oncoprotein degradation via autophagy-lysosomal pathway. |
| title_sort | proteasomal inhibition triggers viral oncoprotein degradation via autophagy lysosomal pathway |
| url | https://doi.org/10.1371/journal.ppat.1008105 |
| work_keys_str_mv | AT chandrimagain proteasomalinhibitiontriggersviraloncoproteindegradationviaautophagylysosomalpathway AT samareshmalik proteasomalinhibitiontriggersviraloncoproteindegradationviaautophagylysosomalpathway AT shaonibhattacharjee proteasomalinhibitiontriggersviraloncoproteindegradationviaautophagylysosomalpathway AT arijitghosh proteasomalinhibitiontriggersviraloncoproteindegradationviaautophagylysosomalpathway AT erlesrobertson proteasomalinhibitiontriggersviraloncoproteindegradationviaautophagylysosomalpathway AT benubratadas proteasomalinhibitiontriggersviraloncoproteindegradationviaautophagylysosomalpathway AT abhiksaha proteasomalinhibitiontriggersviraloncoproteindegradationviaautophagylysosomalpathway |