1
|
Sun Y, Shi D, Sun J, Zhang Y, Liu W, Luo B. Regulation mechanism of EBV-encoded EBER1 and LMP2A on YAP1 and the impact of YAP1 on the EBV infection status in EBV-associated gastric carcinoma. Virus Res 2024; 343:199352. [PMID: 38462175 PMCID: PMC10982081 DOI: 10.1016/j.virusres.2024.199352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/07/2024] [Accepted: 03/07/2024] [Indexed: 03/12/2024]
Abstract
This study aims to explore the role and regulatory mechanism of Yes-associated protein 1 (YAP1) in the development of Epstein-Barr virus-associated gastric cancer (EBVaGC). Here we showed that EBV can upregulate the expression and activity of YAP1 protein through its encoded latent products EBV-encoded small RNA 1 (EBER1) and latent membrane protein 2A (LMP2A), enhancing the malignant characteristics of EBVaGC cells. In addition, we also showed that overexpression of YAP1 induced the expression of EBV encoding latent and lytic phase genes and proteins in the epithelial cell line AGS-EBV infected with EBV, and increased the copy number of the EBV genome, while loss of YAP1 expression reduced the aforementioned indicators. Moreover, we found that YAP1 enhanced EBV lytic reactivation induced by two known activators, 12-O-tetradecanoylhorbol-13-acetate (TPA) and sodium butyrate (NaB). These results indicated a bidirectional regulatory mechanism between EBV and YAP1 proteins, providing new experimental evidence for further understanding the regulation of EBV infection patterns and carcinogenic mechanisms in gastric cancer.
Collapse
Affiliation(s)
- Yujie Sun
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao 266071, China
| | - Duo Shi
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao 266071, China
| | - Jiting Sun
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao 266071, China
| | - Yan Zhang
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao 266071, China; Department of Clinical Laboratory, Zibo Central Hospital, ZiBo 255036, China
| | - Wen Liu
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao 266071, China.
| | - Bing Luo
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao 266071, China.
| |
Collapse
|
2
|
Delgado AL, Preston-Hurlburt P, Lim N, Sumida TS, Long SA, McNamara J, Serti E, Higdon L, Herold KC. Latent EBV impairs immune cell signaling and enhances the efficacy of anti-CD3 mAb in Type 1 Diabetes. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.07.11.23292344. [PMID: 37502867 PMCID: PMC10370230 DOI: 10.1101/2023.07.11.23292344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Teplizumab has been approved for the delay of the onset of type 1 diabetes and may modulate new onset disease. We found that patients who were EBV positive at baseline had a more robust response to drug in two clinical trials and therefore postulated that latent virus has general effects in modifying immune responses. We compared the phenotypes, transcriptomes, and development of peripheral blood cells before and after teplizumab treatment. Higher number of Tregs and partially exhausted CD8 + T cells were found in EBV seropositive individuals at the baseline in the TN10 trial and AbATE trial. Single cell transcriptomics and functional assays identified downregulation of the T cell receptor and other signaling pathways before treatment. Impairments in function of adaptive immune cells were enhanced by teplizumab treatment in EBV seropositive individuals. Our data indicate that EBV can impair signaling pathways generally in immune cells, that broadly redirect cell differentiation.
Collapse
|
3
|
Liew K, Yu GQS, Wei Pua LJ, Wong LZ, Tham SY, Hii LW, Lim WM, OuYong BM, Looi CK, Mai CW, Fei-Lei Chung F, Tan LP, Ahmad M, Soo-Beng Khoo A, Leong CO. Parallel genome-wide RNAi screens identify lymphocyte-specific protein tyrosine kinase (LCK) as a targetable vulnerability of cell proliferation and chemoresistance in nasopharyngeal carcinoma. Cancer Lett 2021; 504:81-90. [PMID: 33587980 DOI: 10.1016/j.canlet.2021.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 02/08/2021] [Indexed: 02/05/2023]
Abstract
Despite recent in advances in the management of nasopharyngeal carcinoma (NPC), development of targeted therapy remains challenging particularly in patients with recurrent or metastatic disease. To search for clinically relevant targets for the treatment of NPC, we carried out parallel genome-wide functional screens to identified essential genes that are required for NPC cells proliferation and cisplatin resistance. We identified lymphocyte-specific protein tyrosine kinase (LCK) as a key vulnerability of both proliferation and cisplatin resistance. Depletion of endogenous LCK or treatment of cells with LCK inhibitor induced tumor-specific cell death and synergized cisplatin sensitivity in EBV-positive C666-1 and EBV-negative SUNE1 cells. Further analyses demonstrated that LCK is regulating the proliferation and cisplatin resistance through activation of signal transducer and activator of transcription 5 (STAT5). Taken together, our study provides a molecular basis for targeting LCK and STAT5 signaling as potential druggable targets for the management of NPC.
Collapse
Affiliation(s)
- Kitson Liew
- Molecular Pathology Unit, Cancer Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health Malaysia, Shah Alam, Selangor, Malaysia
| | - Gibson Qi Sheng Yu
- School of Medicine, International Medical University, Kuala Lumpur, Malaysia
| | - Lesley Jia Wei Pua
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; School of Postgraduate Studies, International Medical University, Kuala Lumpur, Malaysia; School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Li Zhe Wong
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; School of Postgraduate Studies, International Medical University, Kuala Lumpur, Malaysia
| | - Shiau Ying Tham
- Molecular Pathology Unit, Cancer Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health Malaysia, Shah Alam, Selangor, Malaysia
| | - Ling-Wei Hii
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; School of Postgraduate Studies, International Medical University, Kuala Lumpur, Malaysia; School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Wei-Meng Lim
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Brian Ming OuYong
- School of Medicine, International Medical University, Kuala Lumpur, Malaysia
| | - Chin King Looi
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; School of Postgraduate Studies, International Medical University, Kuala Lumpur, Malaysia
| | - Chun-Wai Mai
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; State Key Laboratory of Oncogenes and Related Genes, Renji-Med X Clinical Stem Cell Research Center, Department of Urology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Felicia Fei-Lei Chung
- Mechanisms of Carcinogenesis Section (MCA), Epigenetics Group (EGE), International Agency for Research on Cancer World Health Organization, Lyon CEDEX 08, France
| | - Lu Ping Tan
- Molecular Pathology Unit, Cancer Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health Malaysia, Shah Alam, Selangor, Malaysia
| | - Munirah Ahmad
- Molecular Pathology Unit, Cancer Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health Malaysia, Shah Alam, Selangor, Malaysia
| | - Alan Soo-Beng Khoo
- Molecular Pathology Unit, Cancer Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health Malaysia, Shah Alam, Selangor, Malaysia; Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; School of Postgraduate Studies, International Medical University, Kuala Lumpur, Malaysia.
| | - Chee-Onn Leong
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur, Malaysia; School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia.
| |
Collapse
|
4
|
Molecular Interactions between Two LMP2A PY Motifs of EBV and WW Domains of E3 Ubiquitin Ligase AIP4. Life (Basel) 2021; 11:life11050379. [PMID: 33922228 PMCID: PMC8190631 DOI: 10.3390/life11050379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/15/2022] Open
Abstract
Interactions involving Epstein–Barr virus (EBV) LMP2A and Nedd4 family E3 ubiquitin–protein ligases promote the ubiquitination of LMP2A-associated proteins, which results in the perturbation of normal B-cell signaling. Here, we solved the solution structure of the WW2 domain of hAIP4 and investigated the binding mode involving the N-terminal domain of LMP2A and the WW2 domain. The WW2 domain presented a conserved WW domain scaffold with a three-stranded anti-parallel β-sheet and bound two PY motifs via different binding mechanisms. Our NMR titration and ITC data demonstrated that the PY motifs of LMP2A can recognize and interact weakly with the XP groove of the WW2 domain (residues located around the third β-strand), and then residues between two PY motifs optimize the binding by interacting with the loop 1 region of the WW2 domain. In particular, the residue Val15 in the hairpin loop region between β1 and β2 of the WW2 domain exhibited unique changes depending on the terminal residues of the PY motif. This result suggested that the hairpin loop is responsible for additional interactions outside the XP groove, and this hypothesis was confirmed in a deuterium exchange experiment. These weak but wide interactions can stabilize the complex formed between the PY and WW domains.
Collapse
|
5
|
Fournier B, Boutboul D, Bruneau J, Miot C, Boulanger C, Malphettes M, Pellier I, Dunogué B, Terrier B, Suarez F, Blanche S, Castelle M, Winter S, Delecluse HJ, Molina T, Picard C, Ehl S, Moshous D, Galicier L, Barlogis V, Fischer A, Neven B, Latour S. Rapid identification and characterization of infected cells in blood during chronic active Epstein-Barr virus infection. J Exp Med 2021; 217:152032. [PMID: 32812031 PMCID: PMC7596820 DOI: 10.1084/jem.20192262] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 05/29/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr virus (EBV) preferentially infects epithelial cells and B lymphocytes and sometimes T and NK lymphocytes. Persistence of EBV-infected cells results in severe lymphoproliferative disorders (LPDs). Diagnosis of EBV-driven T or NK cell LPD and chronic active EBV diseases (CAEBV) is difficult, often requiring biopsies. Herein, we report a flow-FISH cytometry assay that detects cells expressing EBV-encoded small RNAs (EBERs), allowing rapid identification of EBV-infected cells among PBMCs. EBV-infected B, T, and/or NK cells were detectable in various LPD conditions. Diagnosis of CAEBV in 22 patients of Caucasian and African origins was established. All exhibited circulating EBV-infected T and/or NK cells, highlighting that CAEBV is not restricted to native American and Asian populations. Proportions of EBV-infected cells correlated with blood EBV loads. We showed that EBV-infected T cells had an effector memory activated phenotype, whereas EBV-infected B cells expressed plasma cell differentiation markers. Thus, this method achieves accurate and unambiguous diagnoses of different forms of EBV-driven LPD and represents a powerful tool to study their pathophysiological mechanisms.
Collapse
Affiliation(s)
- Benjamin Fournier
- Laboratory of Lymphocyte Activation and Susceptibility to EBV Infection, Institut National de la Santé et de la Recherche Médicale UMR 1163, Imagine Institute, Paris, France.,Université de Paris, Paris, France
| | - David Boutboul
- Department of Clinical Immunology, Saint-Louis Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Julie Bruneau
- Université de Paris, Paris, France.,Department of Pathology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Charline Miot
- Department of Pediatric Immunology Hematology and Oncology, University Hospital, Angers, France
| | - Cécile Boulanger
- Institut Roi Albert II, Cancerology and Hematology Departments, University Clinics Saint-Luc Hospital, Brussels, Belgium
| | - Marion Malphettes
- Department of Clinical Immunology, Saint-Louis Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Isabelle Pellier
- Department of Pediatric Immunology Hematology and Oncology, University Hospital, Angers, France
| | - Bertrand Dunogué
- Department of Internal Medicine, Cochin Hospital, National Referral Centre for Systemic and Autoimmune Diseases, Cochin Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Benjamin Terrier
- Department of Internal Medicine, Cochin Hospital, National Referral Centre for Systemic and Autoimmune Diseases, Cochin Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Felipe Suarez
- Department of Adult Hematology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Stéphane Blanche
- Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Martin Castelle
- Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Sarah Winter
- Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Henri-Jacques Delecluse
- Unit F100, Institut National de la Santé et de la Recherche Médicale U1074, Deutsches Krebsforschungszentrum, German Cancer Research Center, Heidelberg, Germany
| | - Thierry Molina
- Université de Paris, Paris, France.,Department of Pathology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Capucine Picard
- Laboratory of Lymphocyte Activation and Susceptibility to EBV Infection, Institut National de la Santé et de la Recherche Médicale UMR 1163, Imagine Institute, Paris, France.,Université de Paris, Paris, France.,Study Center for Primary Immunodeficiencies, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Stephan Ehl
- Institute for Immunodeficiency-Center for Chronic Immunodeficiency, Department of Pediatrics and Adolescent Medicine, Medical Center - Faculty of Medicine, University of Freiburg, Germany
| | - Despina Moshous
- Université de Paris, Paris, France.,Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Lionel Galicier
- Department of Clinical Immunology, Saint-Louis Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Vincent Barlogis
- Department of Pediatric Hematology-Oncology, La Timone Hospital, Marseille, France
| | - Alain Fischer
- Université de Paris, Paris, France.,Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France.,Collège de France, Paris, France.,Institut National de la Santé et de la Recherche Médicale UMR 1163, Paris, France
| | - Bénédicte Neven
- Université de Paris, Paris, France.,Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Sylvain Latour
- Laboratory of Lymphocyte Activation and Susceptibility to EBV Infection, Institut National de la Santé et de la Recherche Médicale UMR 1163, Imagine Institute, Paris, France.,Université de Paris, Paris, France
| |
Collapse
|
6
|
The c-Jun and JunB transcription factors facilitate the transit of classical Hodgkin lymphoma tumour cells through G 1. Sci Rep 2018; 8:16019. [PMID: 30375407 PMCID: PMC6207696 DOI: 10.1038/s41598-018-34199-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 10/07/2018] [Indexed: 12/29/2022] Open
Abstract
Classical Hodgkin Lymphoma (cHL) is primarily a B cell lymphoid neoplasm and a member of the CD30–positive lymphomas. cHL and the other CD30–positive lymphomas are characterized by the elevated expression and/or constitutive activation of the activator protein-1 (AP-1) family transcription factors, c-Jun and JunB; however, the specific roles they play in the pathobiology of cHL are unclear. In this report we show that reducing either c-Jun or JunB expression with short-hairpin RNAs (shRNAs) reduced the growth of cHL cell lines in vitro and in vivo, primarily through impairing cell cycle transition through G1. We further investigated the effect of c-Jun and JunB knock-down on proliferation in another CD30–positive lymphoma, anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL). We found that JunB knock-down in most ALK+ ALCL cell lines examined also resulted in reduced proliferation that was associated with a G0/G1 cell cycle defect. In contrast, c-Jun knock-down in multiple ALK+ ALCL cell lines had no effect on proliferation. In summary, this study directly establishes that both c-Jun and JunB play roles in promoting HRS cell proliferation. Furthermore, we demonstrate there are similarities and differences in c-Jun and JunB function between cHL and ALK+ ALCL.
Collapse
|
7
|
Pawlak EN, Dirk BS, Jacob RA, Johnson AL, Dikeakos JD. The HIV-1 accessory proteins Nef and Vpu downregulate total and cell surface CD28 in CD4 + T cells. Retrovirology 2018; 15:6. [PMID: 29329537 PMCID: PMC5767034 DOI: 10.1186/s12977-018-0388-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 12/20/2017] [Indexed: 12/20/2022] Open
Abstract
Background The HIV-1 accessory proteins Nef and Vpu alter cell surface levels of multiple host proteins to modify the immune response and increase viral persistence. Nef and Vpu can downregulate cell surface levels of the co-stimulatory molecule CD28, however the mechanism of this function has not been completely elucidated. Results Here, we provide evidence that Nef and Vpu decrease cell surface and total cellular levels of CD28. Moreover, using inhibitors we implicate the cellular degradation machinery in the downregulation of CD28. We shed light on the mechanisms of CD28 downregulation by implicating the Nef LL165 and DD175 motifs in decreasing cell surface CD28 and Nef DD175 in decreasing total cellular CD28. Moreover, the Vpu LV64 and S52/56 motifs were required for cell surface CD28 downregulation, while, unlike for CD4 downregulation, Vpu W22 was dispensable. The Vpu S52/56 motif was also critical for Vpu-mediated decreases in total CD28 protein level. Finally, the ability of Vpu to downregulate CD28 is conserved between multiple group M Vpu proteins and infection with viruses encoding or lacking Nef and Vpu have differential effects on activation upon stimulation. Conclusions We report that Nef and Vpu downregulate cell surface and total cellular CD28 levels. We identified inhibitors and mutations within Nef and Vpu that disrupt downregulation, shedding light on the mechanisms utilized to downregulate CD28. The conservation and redundancy between the abilities of two HIV-1 proteins to downregulate CD28 highlight the importance of this function, which may contribute to the development of latently infected cells. Electronic supplementary material The online version of this article (10.1186/s12977-018-0388-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Emily N Pawlak
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Brennan S Dirk
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Rajesh Abraham Jacob
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Aaron L Johnson
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, Dental Sciences Building, Room 3007J, London, ON, N6A 5C1, Canada.
| |
Collapse
|
8
|
Oxidative stress enables Epstein-Barr virus-induced B-cell transformation by posttranscriptional regulation of viral and cellular growth-promoting factors. Oncogene 2015; 35:3807-16. [PMID: 26592445 DOI: 10.1038/onc.2015.450] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/14/2015] [Accepted: 10/22/2015] [Indexed: 12/13/2022]
Abstract
Infection of human B lymphocytes by Epstein-Barr virus (EBV) leads to the establishment of immortalized lymphoblastoid cell lines (LCLs) that are widely used as a model of viral oncogenesis. An early consequence of infection is the induction of DNA damage and activation of the DNA damage response, which limits the efficiency of growth transformation. The cause of the DNA damage remains poorly understood. We have addressed this question by comparing the response of B lymphocytes infected with EBV or stimulated with a potent B-cell mitogen. We found that although the two stimuli induce comparable proliferation during the first 10 days of culture, the EBV-infected blasts showed significantly higher levels of DNA damage, which correlated with stronger and sustained accumulation of reactive oxygen species (ROS). Treatment with ROS scavengers decreased DNA damage in both mitogen-stimulated and EBV-infected cells. However, while mitogen-induced proliferation was slightly improved, the proliferation of EBV-infected cells and the establishment of LCLs were severely impaired. Quenching of ROS did not affect the kinetics and magnitude of viral gene expression but was associated with selective downregulation of the viral LMP1 and phosphorylated cellular transcription factor STAT3 that have key roles in transformation. Analysis of the mechanism by which high levels of ROS support LMP1 expression revealed selective inhibition of viral microRNAs that target the LMP1 transcript. Our study provides novel insights into the role of EBV-induced oxidative stress in promoting B-cell immortalization and malignant transformation.
Collapse
|
9
|
Abstract
LMP2A is an EBV-encoded protein with three domains: (a) an N-terminal cytoplasmic domain, which has PY motifs that bind to WW domain-containing E3 ubiquitin ligases and an ITAM that binds to SH2 domain-containing proteins, (b) a transmembrane domain with 12 transmembrane segments that localizes LMP2A in cellular membranes, and (c) a 27-amino acid C-terminal domain which mediates homodimerization and heterodimerization of LMP2 protein isoforms. The most prominent two isoforms of the protein are LMP2A and LMP2B. The LMP2B isoform lacks the 19-amino acid N-terminal domain found in LMP2A, which modulates cellular signaling resulting in a baseline activation of B cells and degradation of cellular kinases leading to the downregulation of normal B cell signaling pathways. These two seemingly contradictory processes allow EBV to establish and maintain latency. LMP2 is expressed in many EBV-associated malignancies. While its antigenic properties may be useful in developing LMP2-specific immunity, the LMP2A N-terminal motifs also provide a basis to target LMP2A-modulated cellular kinases for the development of treatment strategies.
Collapse
|
10
|
Pearson JD, Zhang J, Wu Z, Thew KD, Rowe KJ, Bacani JTC, Ingham RJ. Expression of granzyme B sensitizes ALK+ ALCL tumour cells to apoptosis-inducing drugs. Mol Cancer 2014; 13:199. [PMID: 25168906 PMCID: PMC4158053 DOI: 10.1186/1476-4598-13-199] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 08/19/2014] [Indexed: 11/10/2022] Open
Abstract
Background The serine protease Granzyme B (GzB) is primarily expressed by cytotoxic T lymphocytes and natural killer cells, and functions in allowing these cells to induce apoptosis in virally-infected or transformed cells. Cancers of both lymphoid and non-lymphoid origin also express GzB, and in some cases this expression has been linked to pathogenesis or sensitizing tumour cells to cell death. For example, GzB expression in urothelial carcinoma was implicated in promoting tumour cell invasion, whereas its expression in nasal-type NK/T lymphomas was found to correlate with increased apoptosis. GzB expression is also a hallmark of the non-Hodgkin lymphoma, anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL). Given the fact that ALK+ ALCL exhibits high levels of apoptosis and is typically responsive to conventional chemotherapy, we examined whether GzB expression might play a role in sensitizing ALK+ ALCL tumour cells to apoptosis. Methods ALK+ ALCL cell lines stably expressing GzB or non-targeting (control) shRNA were generated and apoptosis was examined by anti-PARP western blotting and terminal deoxynucleotidyl transferase dUTP nick end labelling. Both spontaneous apoptosis and apoptosis in response to treatment with staurosporine or doxorubicin were investigated. In order to assess whether additional granzymes might be important in promoting cell death in ALK+ ALCL, we examined whether other human granzymes were expressed in ALK+ ALCL cell lines using reverse-transcriptase PCR and western blotting. Results Expression of several GzB shRNAs in multiple ALK+ ALCL cell lines resulted in a significant decrease in GzB levels and activity. While spontaneous apoptosis was similar in ALK+ ALCL cell lines expressing either GzB or control shRNA, GzB shRNA-expressing cells were less sensitive to staurosporine or doxorubicin-induced apoptosis as evidenced by reduced PARP cleavage and decreased DNA fragmentation. Furthermore, we found that GzB is the only granzyme that is expressed at significant levels in ALK+ ALCL cell lines. Conclusions Our findings are the first to demonstrate that GzB expression sensitizes ALK+ ALCL cell lines to drug-induced apoptosis. This suggests that GzB expression may be a factor contributing to the favourable response of this lymphoma to treatment.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Robert J Ingham
- Department of Medical Microbiology and Immunology and Li Ka Shing Institute of Virology, University of Alberta, Katz Group Centre for Pharmacy and Health Research, University of Alberta, Edmonton AB T6G 2E1, Canada.
| |
Collapse
|
11
|
Chandrasekaran P, Buckley M, Moore V, Wang LQ, Kehrl JH, Venkatesan S. HIV-1 Nef impairs heterotrimeric G-protein signaling by targeting Gα(i2) for degradation through ubiquitination. J Biol Chem 2012; 287:41481-98. [PMID: 23071112 DOI: 10.1074/jbc.m112.361782] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The HIV Nef protein is an important pathogenic factor that modulates cell surface receptor trafficking and impairs cell motility, presumably by interfering at multiple steps with chemotactic receptor signaling. Here, we report that a dominant effect of Nef is to trigger AIP4 E3 ligase-mediated Gα(i2) ubiquitination, which leads to Gα(i2) endolysosomal sequestration and destruction. The loss of the Gα(i2) subunit was demonstrable in many cell types in the context of gene transfection, HIV infection, or Nef protein transduction. Nef directly interacts with Gα(i2) and ternary complexes containing AIP4, Nef, and Gα(i2) form. A substantial reversal of Gα(i2) loss and a partial recovery of impaired chemotaxis occurred following siRNA knockdown of AIP4 or NEDD4 or by inhibiting dynamin. The N-terminal myristoyl group, (62)EEEE(65) motif, and (72)PXXP(75) motif of Nef are critical for this effect to occur. Nef expression does not affect a Gq(i5) chimera where the five C-terminal residues of Gq are replaced with those of Gα(i2). Lysine at position 296 of Gα(i2) was identified as the critical determinant of Nef-induced degradation. By specifically degrading Gα(i2), Nef directly subverts leukocyte migration and homing. Impaired trafficking and homing of HIV Nef-expressing lymphocytes probably contributes to early immune dysfunction following HIV infection.
Collapse
Affiliation(s)
- Prabha Chandrasekaran
- Laboratory of Molecular Immunology, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | | | | | |
Collapse
|
12
|
Pearson JD, Mohammed Z, Bacani JTC, Lai R, Ingham RJ. The heat shock protein-90 co-chaperone, Cyclophilin 40, promotes ALK-positive, anaplastic large cell lymphoma viability and its expression is regulated by the NPM-ALK oncoprotein. BMC Cancer 2012; 12:229. [PMID: 22681779 PMCID: PMC3407532 DOI: 10.1186/1471-2407-12-229] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 06/08/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL) is a T cell lymphoma defined by the presence of chromosomal translocations involving the ALK tyrosine kinase gene. These translocations generate fusion proteins (e.g. NPM-ALK) with constitutive tyrosine kinase activity, which activate numerous signalling pathways important for ALK+ ALCL pathogenesis. The molecular chaperone heat shock protein-90 (Hsp90) plays a critical role in allowing NPM-ALK and other signalling proteins to function in this lymphoma. Co-chaperone proteins are important for helping Hsp90 fold proteins and for directing Hsp90 to specific clients; however the importance of co-chaperone proteins in ALK+ ALCL has not been investigated. Our preliminary findings suggested that expression of the immunophilin co-chaperone, Cyclophilin 40 (Cyp40), is up-regulated in ALK+ ALCL by JunB, a transcription factor activated by NPM-ALK signalling. In this study we examined the regulation of the immunophilin family of co-chaperones by NPM-ALK and JunB, and investigated whether the immunophilin co-chaperones promote the viability of ALK+ ALCL cell lines. METHODS NPM-ALK and JunB were knocked-down in ALK+ ALCL cell lines with siRNA, and the effect on the expression of the three immunophilin co-chaperones: Cyp40, FK506-binding protein (FKBP) 51, and FKBP52 examined. Furthermore, the effect of knock-down of the immunophilin co-chaperones, either individually or in combination, on the viability of ALK+ ALCL cell lines and NPM-ALK levels and activity was also examined. RESULTS We found that NPM-ALK promoted the transcription of Cyp40 and FKBP52, but only Cyp40 transcription was promoted by JunB. We also observed reduced viability of ALK+ ALCL cell lines treated with Cyp40 siRNA, but not with siRNAs directed against FKBP52 or FKBP51. Finally, we demonstrate that the decrease in the viability of ALK+ ALCL cell lines treated with Cyp40 siRNA does not appear to be due to a decrease in NPM-ALK levels or the ability of this oncoprotein to signal. CONCLUSIONS This is the first study demonstrating that the expression of immunophilin family co-chaperones is promoted by an oncogenic tyrosine kinase. Moreover, this is the first report establishing an important role for Cyp40 in lymphoma.
Collapse
Affiliation(s)
- Joel D Pearson
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, T6G 2E1, Canada
| | - Zubair Mohammed
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, T6G 2E1, Canada
| | - Julinor T C Bacani
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, T6G 2B7, Canada
| | - Raymond Lai
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, T6G 2B7, Canada
| | - Robert J Ingham
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, T6G 2E1, Canada
| |
Collapse
|
13
|
Dergai OV, Dergai MV, Skrypkina IY, Tsyba LO, Yaruchik AM, Rynditch AV. Amphiphysin 1 and 2 interact with latent membrane protein 2A of Epstein-Barr virus and regulate its exosomal secretion. ACTA ACUST UNITED AC 2012. [DOI: 10.7124/bc.000054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- O. V. Dergai
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - M. V. Dergai
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - I. Ya. Skrypkina
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - L. O. Tsyba
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - A. M. Yaruchik
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| | - A. V. Rynditch
- Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine
| |
Collapse
|
14
|
Bhandari D, Robia SL, Marchese A. The E3 ubiquitin ligase atrophin interacting protein 4 binds directly to the chemokine receptor CXCR4 via a novel WW domain-mediated interaction. Mol Biol Cell 2008; 20:1324-39. [PMID: 19116316 DOI: 10.1091/mbc.e08-03-0308] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The E3 ubiquitin ligase atrophin interacting protein 4 (AIP4) mediates ubiquitination and down-regulation of the chemokine receptor CXCR4. AIP4 belongs to the Nedd4-like homologous to E6-AP carboxy terminus domain family of E3 ubiquitin ligases, which typically bind proline-rich motifs within target proteins via the WW domains. The intracellular domains of CXCR4 lack canonical WW domain binding motifs; thus, whether AIP4 is targeted to CXCR4 directly or indirectly via an adaptor protein remains unknown. Here, we show that AIP4 can interact directly with CXCR4 via a novel noncanonical WW domain-mediated interaction involving serine residues 324 and 325 within the carboxy-terminal tail of CXCR4. These serine residues are critical for mediating agonist-promoted binding of AIP4 and subsequent ubiquitination and degradation of CXCR4. These residues are phosphorylated upon agonist activation and phosphomimetic mutants show enhanced binding to AIP4, suggesting a mechanism whereby phosphorylation mediates the interaction between CXCR4 and AIP4. Our data reveal a novel noncanonical WW domain-mediated interaction involving phosphorylated serine residues in the absence of any proline residues and suggest a novel mechanism whereby an E3 ubiquitin ligase is targeted directly to an activated G protein-coupled receptor.
Collapse
Affiliation(s)
- Deepali Bhandari
- Program in Molecular Biology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | | | | |
Collapse
|
15
|
|
16
|
Morales B, Ramirez-Espain X, Shaw AZ, Martin-Malpartida P, Yraola F, Sánchez-Tilló E, Farrera C, Celada A, Royo M, Macias MJ. NMR structural studies of the ItchWW3 domain reveal that phosphorylation at T30 inhibits the interaction with PPxY-containing ligands. Structure 2007; 15:473-83. [PMID: 17437719 DOI: 10.1016/j.str.2007.03.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Revised: 03/08/2007] [Accepted: 03/14/2007] [Indexed: 11/26/2022]
Abstract
In this work, we study the role of phosphorylation as a regulatory mechanism for the interaction between the E3 ubiquitin ligase ItchWW3 domain and two PPxY motifs of one of its targets, the Epstein-Barr virus latent membrane protein 2A. Whereas ligand phosphorylation only diminishes binding, domain phosphorylation at residue T30 abrogates it. We show that two ItchWW domains can be phosphorylated at this position, using CK2 and PKA kinases and/or with stimulated T lymphocyte lysates. To better understand the regulation process, we determined the NMR structures of the ItchWW3-PPxY complex and of the phosphoT30-ItchWW3 variant. The peptide binds the domain using both XP and tyrosine grooves. A hydrogen bond from T30 to the ligand is also detected. This hydrogen-bond formation is precluded in the variant, explaining the inhibition upon phosphorylation. Our results suggest that phosphorylation at position 30 in ItchWW domains can be a mechanism to inhibit target recognition in vivo.
Collapse
Affiliation(s)
- Begoña Morales
- Institute of Research in Biomedicine, Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Grande SM, Bannish G, Fuentes-Panana EM, Katz E, Monroe JG. Tonic B-cell and viral ITAM signaling: context is everything. Immunol Rev 2007; 218:214-34. [PMID: 17624955 DOI: 10.1111/j.1600-065x.2007.00535.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The presence of an immunoreceptor tyrosine-based activation motif (ITAM) makes immunoreceptors different from other signaling receptors, like integrins, G-coupled protein receptors, chemokine receptors, and growth factor receptors. This unique motif has the canonical sequence D/Ex(0-2)YxxL/Ix(6-8)YxxL/I, where x represents any amino acid and is present at least once in all immunoreceptor complexes. Immunoreceptors can promote survival, activation, and differentiation by transducing signals through these highly conserved motifs. Traditionally, ITAM signaling is thought to occur in response to ligand-induced aggregation, although evidence indicates that ligand-independent tonic signaling also provides functionally relevant signals. The majority of proteins containing ITAMs are transmembrane proteins that exist as part of immunoreceptor complexes. However, oncogenic viruses also have ITAM-containing proteins. In this review, we discuss what is known about tonic signaling by both cellular and viral ITAM-containing proteins and speculate what we might learn from each context.
Collapse
Affiliation(s)
- Shannon M Grande
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | | | | |
Collapse
|
18
|
Lim CS, Seet BT, Ingham RJ, Gish G, Matskova L, Winberg G, Ernberg I, Pawson T. The K15 protein of Kaposi's sarcoma-associated herpesvirus recruits the endocytic regulator intersectin 2 through a selective SH3 domain interaction. Biochemistry 2007; 46:9874-85. [PMID: 17696407 DOI: 10.1021/bi700357s] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Kaposi's sarcoma-associated herpesvirus, also known as human herpesvirus 8, is closely associated with several cancers including Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. The rightmost end of the KSHV genome encodes a protein, K15, with multiple membrane-spanning segments and an intracellular carboxy-terminal tail that contains several conserved motifs with the potential to recruit interaction domains (i.e., SH2, SH3, TRAF) of host cell proteins. K15 has been implicated in downregulating B cell receptor (BCR) signaling through its conserved motifs and may thereby play a role in maintaining viral latency and/or preventing apoptosis of the infected B cells. However, K15's mode of action is largely unknown. We have used mass spectrometry, domain and peptide arrays, and surface plasmon resonance to identify binding partners for a conserved proline-rich sequence (PPLP) in the K15 cytoplasmic tail. We show that the PPLP motif selectively binds the SH3-C domain of an endocytic adaptor protein, Intersectin 2 (ITSN2). This interaction can be observed both in vitro and in cells, where K15 and ITSN2 colocalize to discrete compartments within the B cell. The ability of K15 to associate with ITSN2 suggests a new role for the K15 viral protein in intracellular protein trafficking.
Collapse
Affiliation(s)
- Caesar S Lim
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Clarkson NG, Simmonds SJ, Puklavec MJ, Brown MH. Direct and indirect interactions of the cytoplasmic region of CD244 (2B4) in mice and humans with FYN kinase. J Biol Chem 2007; 282:25385-94. [PMID: 17599905 DOI: 10.1074/jbc.m704483200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Engagement of the receptor CD244 (2B4) by its ligand CD48 has inhibitory and activating potential, and this differs depending on experimental systems in mouse and human. We show that, in both mouse and human upon engagement of its ligand CD48, CD244 can give a negative signal to natural killer cells, implying conservation of function between the two species. The signaling mechanisms used by CD244 in both human and mouse are conserved as shown by quantitative analyses of the direct molecular interactions of the SH2 domains of the adaptors SLAM-associated protein (SAP) and EAT-2 and of FYN kinase with CD244 together with the indirect interactions of the FYN SH2 domain with EAT-2. Functional experiments support the biochemical hierarchy of interactions and show that EAT-2 is not inhibitory per se. The data are consistent with a model in which the mechanism of signal transduction by CD244 is to regulate FYN kinase recruitment and/or activity and the outcome of CD48/CD244 interactions is determined by which other receptors are engaged.
Collapse
Affiliation(s)
- Nicholas G Clarkson
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom
| | | | | | | |
Collapse
|
20
|
Matskova LV, Helmstetter C, Ingham RJ, Gish G, Lindholm CK, Ernberg I, Pawson T, Winberg G. The Shb signalling scaffold binds to and regulates constitutive signals from the Epstein–Barr virus LMP2A membrane protein. Oncogene 2007; 26:4908-17. [PMID: 17311000 DOI: 10.1038/sj.onc.1210298] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Epstein-Barr virus latency-associated membrane protein LMP2A has been shown to activate the survival kinase Akt in epithelial and B cells in a phosphoinositide 3-kinase-dependent fashion. In this study, we demonstrate that the signalling scaffold Shb associates through SH2 and PTB domain interactions with phosphorylated tyrosine motifs in the LMP2A N-terminal tail. Additionally, we show that mutation of tyrosines in these motifs as well as shRNA-mediated downregulation of Shb leads to a loss of constitutive Akt-activation in LMP2A-expressing cells. Furthermore, utilization by Shb of the LMP2A ITAM motif regulates stability of the Syk tyrosine kinase in LMP2A-expressing cells. Our data set the precedent for viral utilization of the Shb signalling scaffold and implicate Shb as a regulator of LMP2A-dependent Akt activation.
Collapse
Affiliation(s)
- L V Matskova
- Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden.
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Abstract
Relatively small genomes and high replication rates allow viruses and bacteria to accumulate mutations. This continuously presents the host immune system with new challenges. On the other side of the trenches, an increasingly well-adjusted host immune response, shaped by coevolutionary history, makes a pathogen's life a rather complicated endeavor. It is, therefore, no surprise that pathogens either escape detection or modulate the host immune response, often by redirecting normal cellular pathways to their advantage. For the purpose of this chapter, we focus mainly on the manipulation of the class I and class II major histocompatibility complex (MHC) antigen presentation pathways and the ubiquitin (Ub)-proteasome system by both viral and bacterial pathogens. First, we describe the general features of antigen presentation pathways and the Ub-proteasome system and then address how they are manipulated by pathogens. We discuss the many human cytomegalovirus (HCMV)-encoded immunomodulatory genes that interfere with antigen presentation (immunoevasins) and focus on the HCMV immunoevasins US2 and US11, which induce the degradation of class I MHC heavy chains by the proteasome by catalyzing their export from the endoplasmic reticulum (ER)-membrane into the cytosol, a process termed ER dislocation. US2- and US11-mediated subversion of ER dislocation ensures proteasomal degradation of class I MHC molecules and presumably allows HCMV to avoid recognition by cytotoxic T cells, whilst providing insight into general aspects of ER-associated degradation (ERAD) which is used by eukaryotic cells to purge their ER of defective proteins. We discuss the similarities and differences between the distinct pathways co-opted by US2 and US11 for dislocation and degradation of human class I MHC molecules and also a putatively distinct pathway utilized by the murine herpes virus (MHV)-68 mK3 immunoevasin for ER dislocation of murine class I MHC. We speculate on the implications of the three pathogen-exploited dislocation pathways to cellular ER quality control. Moreover, we discuss the ubiquitin (Ub)-proteasome system and its position at the core of antigen presentation as proteolysis and intracellular trafficking rely heavily on Ub-dependent processes. We add a few examples of manipulation of the Ub-proteasome system by pathogens in the context of the immune system and such diverse aspects of the host-pathogen relationship as virus budding, bacterial chromosome integration, and programmed cell death, to name a few. Finally, we speculate on newly found pathogen-encoded deubiquitinating enzymes (DUBs) and their putative roles in modulation of host-pathogen interactions.
Collapse
Affiliation(s)
- Joana Loureiro
- Whitehead Institute, 9 Cambridge Center, Cambridge, Massachusetts, USA
| | | |
Collapse
|