30 results on '"Qiliang Cai"'
Search Results
2. Correction for Mo et al., 'Lactic Acid Downregulates Viral MicroRNA To Promote Epstein-Barr Virus-Immortalized B Lymphoblastic Cell Adhesion and Growth'
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Yin Tong, Caixia Zhu, Qing Zhu, Fei Tan, Zhenghong Yuan, Fang Wei, Xiaohui Mo, Ling Ding, Erle S. Robertson, Yuyan Wang, Qian Yu, Qiliang Cai, Shujuan Du, and Yeqiang Liu
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Immunology ,Biology ,medicine.disease_cause ,Microbiology ,Epstein–Barr virus ,Molecular biology ,Lactic acid ,Virus-Cell Interactions ,chemistry.chemical_compound ,chemistry ,Virology ,Insect Science ,hemic and lymphatic diseases ,microRNA ,medicine ,Cell adhesion - Abstract
High plasma lactate is associated with poor prognosis of many malignancies, but its role in virally mediated cancer progression and underlying molecular mechanisms are unclear. Epstein-Barr virus (EBV), the first human oncogenic virus, causes several cancers, including B-cell lymphoma. Here, we report that lactate dehydrogenase A (LDH-A) expression and lactate production are elevated in EBV-immortalized B lymphoblastic cells, and lactic acid (LA; acidic lactate) at low concentration triggers EBV-infected B-cell adhesion, morphological changes, and proliferation in vitro and in vivo. Moreover, LA-induced responses of EBV-infected B cells uniquely occurs in viral latency type III, and it is dramatically associated with the inhibition of global viral microRNAs, particularly the miR-BHRF1 cluster, and the high expression of SMAD3, JUN, and COL1A genes. The introduction of miR-BHRF1-1 blocks the LA-induced effects of EBV-infected B cells. Thus, this may be a novel mechanism to explain EBV-immortalized B lymphoblastic cell malignancy in an LA microenvironment.
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- 2021
3. Lactic Acid Downregulates Viral MicroRNA To Promote Epstein-Barr Virus-Immortalized B Lymphoblastic Cell Adhesion and Growth
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Shujuan Du, Xiaohui Mo, Caixia Zhu, Yeqiang Liu, Zhenghong Yuan, Qian Yu, Ling Ding, Erle S. Robertson, Qiliang Cai, Yin Tong, Fang Wei, Fei Tan, Qing Zhu, and Yuyan Wang
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0301 basic medicine ,Epstein-Barr Virus Infections ,Herpesvirus 4, Human ,Cell Survival ,MAP Kinase Kinase 4 ,Lactate dehydrogenase A ,Immunology ,Cell ,Biology ,medicine.disease_cause ,Microbiology ,Collagen Type I ,Virus ,03 medical and health sciences ,hemic and lymphatic diseases ,Virology ,Tumor Virus ,Cell Adhesion ,Tumor Microenvironment ,medicine ,Humans ,Lactic Acid ,Smad3 Protein ,Author Correction ,education ,Cell adhesion ,Cell Line, Transformed ,Cell Proliferation ,B-Lymphocytes ,education.field_of_study ,Tumor microenvironment ,L-Lactate Dehydrogenase ,Precursor Cell Lymphoblastic Leukemia-Lymphoma ,Epstein–Barr virus ,Virus Latency ,Collagen Type I, alpha 1 Chain ,Isoenzymes ,MicroRNAs ,030104 developmental biology ,medicine.anatomical_structure ,Insect Science ,Cancer research ,Lactate Dehydrogenase 5 ,Oncovirus - Abstract
High plasma lactate is associated with poor prognosis of many malignancies, but its role in virally mediated cancer progression and underlying molecular mechanisms are unclear. Epstein-Barr virus (EBV), the first human oncogenic virus, causes several cancers, including B-cell lymphoma. Here, we report that lactate dehydrogenase A (LDH-A) expression and lactate production are elevated in EBV-immortalized B lymphoblastic cells, and lactic acid (LA; acidic lactate) at low concentration triggers EBV-infected B-cell adhesion, morphological changes, and proliferation in vitro and in vivo . Moreover, LA-induced responses of EBV-infected B cells uniquely occurs in viral latency type III, and it is dramatically associated with the inhibition of global viral microRNAs, particularly the miR-BHRF1 cluster, and the high expression of SMAD3 , JUN , and COL1A genes. The introduction of miR-BHRF1-1 blocks the LA-induced effects of EBV-infected B cells. Thus, this may be a novel mechanism to explain EBV-immortalized B lymphoblastic cell malignancy in an LA microenvironment. IMPORTANCE The tumor microenvironment is complicated, and lactate, which is created by cell metabolism, contributes to an acidic microenvironment that facilitates cancer progression. However, how LA operates in virus-associated cancers is unclear. Thus, we studied how EBV (the first tumor virus identified in humans; it is associated with many cancers) upregulates the expression of LDH-A and lactate production in B lymphoma cells. Elevated LA induces adhesion and the growth of EBV-infected B cells by inhibiting viral microRNA transcription. Thus, we offer a novel understanding of how EBV utilizes an acidic microenvironment to promote cancer development.
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- 2018
4. Constitutive Activation of Interleukin-13/STAT6 Contributes to Kaposi's Sarcoma-Associated Herpesvirus-Related Primary Effusion Lymphoma Cell Proliferation and Survival
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Chong Wang, Yanling Feng, Xiaohui Mo, Erle S. Robertson, Zhenghong Yuan, Caixia Zhu, Fang Wei, Jianqing Xu, Liming Zhang, and Qiliang Cai
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Cell Survival ,viruses ,Immunology ,Biology ,medicine.disease_cause ,Microbiology ,chemistry.chemical_compound ,Cell Line, Tumor ,Lymphoma, Primary Effusion ,Virology ,medicine ,Humans ,Phosphorylation ,Kaposi's sarcoma-associated herpesvirus ,Sarcoma, Kaposi ,Cell Proliferation ,STAT6 ,B-Lymphocytes ,Interleukin-13 ,Janus kinase 2 ,integumentary system ,Janus kinase 1 ,Protein Tyrosine Phosphatase, Non-Receptor Type 6 ,Cell Cycle ,Virion ,virus diseases ,Tyrosine phosphorylation ,Janus Kinase 1 ,Janus Kinase 2 ,medicine.disease ,Antibodies, Neutralizing ,Virus Latency ,Virus-Cell Interactions ,HEK293 Cells ,Gene Expression Regulation ,chemistry ,Insect Science ,Herpesvirus 8, Human ,Host-Pathogen Interactions ,Cancer research ,biology.protein ,STAT protein ,Primary effusion lymphoma ,STAT6 Transcription Factor ,Janus kinase ,Signal Transduction - Abstract
Activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway has been associated with numerous human malignancies, including primary effusion lymphomas (PELs). PEL, a cancerous proliferation of B cells, is caused by Kaposi's sarcoma-associated herpesvirus (KSHV). Previously we identified constitutive phosphorylation of STAT6 on tyrosine 641 (p-STAT6 C ) in PEL cell lines BC3 and BCBL1; however, the molecular mechanism leading to this activation remains unclear. Here we demonstrate that STAT6 activation tightly correlates with interleukin-13 (IL-13) secretion, JAK1/2 tyrosine phosphorylation, and reduced expression of SHP1 due to KSHV infection. Moreover, p-STAT6 C and reduction of SHP1 were also observed in KS patient tissue. Notably, blockade of IL-13 by antibody neutralization dramatically inhibits PEL cell proliferation and survival. Taken together, these results suggest that IL-13/STAT6 signaling is modulated by KSHV to promote host cell proliferation and viral pathogenesis. IMPORTANCE STAT6 is a member of signal transducer and activator of transcription (STAT) family, whose activation is linked to KSHV-associated cancers. The mechanism through which STAT6 is modulated by KSHV remains unclear. In this study, we demonstrated that constitutive activation of STAT6 in KSHV-associated PEL cells results from interleukin-13 (IL-13) secretion and reduced expression of SHP1. Importantly, we also found that depletion of IL-13 reduces PEL cell growth and survival. This discovery provides new insight that IL-13/STAT6 plays an essential role in KSHV pathogenesis.
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- 2015
5. Inhibition of KAP1 Enhances Hypoxia-Induced Kaposi's Sarcoma-Associated Herpesvirus Reactivation through RBP-Jκ
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Subhash C. Verma, Fang Wei, Qiliang Cai, Jing Qin, Jie Lu, Shuvomoy Banerjee, Erle S. Robertson, Junwen Wang, Yi Guo, Hong Shang, Zhenghong Yuan, Liming Zhang, and Caixia Zhu
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viruses ,Viral pathogenesis ,Immunology ,Tripartite Motif-Containing Protein 28 ,Biology ,medicine.disease_cause ,Microbiology ,chemistry.chemical_compound ,Cell Line, Tumor ,Virology ,Virus latency ,medicine ,Humans ,Kaposi's sarcoma-associated herpesvirus ,Hypoxia ,Sarcoma, Kaposi ,Cell Cycle ,virus diseases ,Sodium butyrate ,biochemical phenomena, metabolism, and nutrition ,Cell cycle ,Hypoxia-Inducible Factor 1, alpha Subunit ,medicine.disease ,Virus Latency ,Virus-Cell Interactions ,Chromatin ,Oxygen ,Repressor Proteins ,chemistry ,Lytic cycle ,Immunoglobulin J Recombination Signal Sequence-Binding Protein ,Insect Science ,Herpesvirus 8, Human ,Cancer research ,Virus Activation ,Primary effusion lymphoma - Abstract
Hypoxia-inducible factor 1α (HIF-1α) has been frequently implicated in many cancers as well as viral pathogenesis. Kaposi's sarcoma-associated herpesvirus (KSHV) is linked to several human malignancies. It can stabilize HIF-1α during latent infection and undergoes lytic replication in response to hypoxic stress. However, the mechanism by which KSHV controls its latent and lytic life cycle through the deregulation of HIF-1α is not fully understood. Our previous studies showed that the hypoxia-sensitive chromatin remodeler KAP1 was targeted by the KSHV-encoded latency-associated nuclear antigen (LANA) to repress expression of the major lytic replication and transcriptional activator (RTA). Here we further report that an RNA interference-based knockdown of KAP1 in KSHV-infected primary effusion lymphoma (PEL) cells disrupted viral episome stability and abrogated sub-G 1 /G 1 arrest of the cell cycle while increasing the efficiency of KSHV lytic reactivation by hypoxia or using the chemical 12- O -tetradecanoylphorbol-13-acetate (TPA) or sodium butyrate (NaB). Moreover, KSHV genome-wide screening revealed that four hypoxia-responsive clusters have a high concurrence of both RBP-Jκ and HIF-1α binding sites (RBS+HRE) within the same gene promoter and are tightly associated with KAP1. Inhibition of KAP1 greatly enhanced the association of RBP-Jκ with the HIF-1α complex for driving RTA expression not only in normoxia but also in hypoxia. These results suggest that both KAP1 and the concurrence of RBS+HRE within the RTA promoter are essential for KSHV latency and hypoxia-induced lytic reactivation. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV), a DNA tumor virus, is an etiological agent linked to several human malignancies, including Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). HIF-1α, a key hypoxia-inducible factor, is frequently elevated in KSHV latently infected tumor cells and contributes to KSHV lytic replication in hypoxia. The molecular mechanisms of how KSHV controls the latent and lytic life cycle through deregulating HIF-1α remain unclear. In this study, we found that inhibition of hypoxia-sensitive chromatin remodeler KAP1 in KSHV-infected PEL cells leads to a loss of viral genome and increases its sensitivity to hypoxic stress, leading to KSHV lytic reactivation. Importantly, we also found that four hypoxia-responsive clusters within the KSHV genome contain a high concurrence of RBP-Jκ (a key cellular regulator involved in Notch signaling) and HIF-1α binding sites. These sites are also tightly associated with KAP1. This discovery implies that KAP1, RBP-Jκ, and HIF-1α play an essential role in KSHV pathogenesis through subtle cross talk which is dependent on the oxygen levels in the infected cells.
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- 2014
6. H2AX Phosphorylation Is Important for LANA-Mediated Kaposi's Sarcoma-Associated Herpesvirus Episome Persistence
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Abhik Saha, Mahadesh Prasad Aj, Hem Chandra Jha, Erle S. Robertson, Qiliang Cai, Jie Lu, and Santosh Kumar Upadhyay
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viruses ,Amino Acid Motifs ,Immunology ,medicine.disease_cause ,environment and public health ,Microbiology ,Cell Line ,Histones ,Mice ,Virology ,Histone H2A ,Virus latency ,medicine ,Animals ,Humans ,Phosphorylation ,Nuclear protein ,Kaposi's sarcoma-associated herpesvirus ,Antigens, Viral ,Gene ,biology ,Nuclear Proteins ,virus diseases ,Herpesviridae Infections ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,Molecular biology ,Virus Latency ,Genome Replication and Regulation of Viral Gene Expression ,enzymes and coenzymes (carbohydrates) ,Histone ,Insect Science ,Herpesvirus 8, Human ,Leukocytes, Mononuclear ,biology.protein ,Chromatin immunoprecipitation ,Plasmids - Abstract
The DNA damage response (DDR) of host cells is utilized by a number of viruses to establish and propagate their genomes in the infected cells. We examined the expression of the DDR genes during Kaposi's sarcoma-associated herpesvirus (KSHV) infection of human peripheral blood mononuclear cells (PBMCs). The genes were mostly downregulated, except H2AX, which was upregulated during infection. H2AX is important for gammaherpesvirus infectivity, and its phosphorylation at serine 139 is crucial for maintenance of latency during mouse gamma-herpesvirus 68 (MHV-68) infection. We now also observed phosphorylation of H2AX at serine 139 during KSHV infection. H2AX is a histone H2A isoform shown to interact with the latency-associated nuclear antigen (LANA) encoded by KSHV. Here, we show that LANA directly interacted with H2AX through domains at both its N and C termini. The phosphorylated form of H2AX (γH2AX) was shown to colocalize with LANA. Chromatin immunoprecipitation (ChIP) assays showed that a reduction in H2AX levels resulted in reduced binding of LANA with KSHV terminal repeats (TRs). Binding preferences of H2AX and γH2AX along the KSHV episome were examined by whole-episome ChIP analysis. We showed that γH2AX had a higher relative binding activity along the TR regions than that of the long unique region (LUR), which highlighted the importance of H2AX phosphorylation during KSHV infection. Furthermore, knockdown of H2AX resulted in decreased KSHV episome copy number. Notably, the C terminus of LANA contributed to phosphorylation of H2AX. However, phosphorylation was not dependent on the ability of LANA to drive KSHV-infected cells into S-phase. Thus, H2AX contributes to association of LANA with the TRs, and phosphorylation of H2AX is likely important for its increased density at the TRs.
- Published
- 2013
7. The Single RBP-Jκ Site within the LANA Promoter Is Crucial for Establishing Kaposi's Sarcoma-Associated Herpesvirus Latency during Primary Infection
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Qiliang Cai, Jie Lu, Subhash C. Verma, and Erle S. Robertson
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Gene Expression Regulation, Viral ,Chromosomes, Artificial, Bacterial ,viruses ,Immunology ,Notch signaling pathway ,Biology ,Recombinant virus ,medicine.disease_cause ,Microbiology ,Immediate early protein ,Cell Line ,Immediate-Early Proteins ,Transactivation ,Virology ,Virus latency ,medicine ,Humans ,Kaposi's sarcoma-associated herpesvirus ,Promoter Regions, Genetic ,Antigens, Viral ,Recombination, Genetic ,Binding Sites ,Nuclear Proteins ,virus diseases ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,Virus Latency ,Genome Replication and Regulation of Viral Gene Expression ,Lytic cycle ,Immunoglobulin J Recombination Signal Sequence-Binding Protein ,Insect Science ,Herpesvirus 8, Human ,Leukocytes, Mononuclear ,Trans-Activators ,Virus Activation ,Primary effusion lymphoma - Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV; or human herpesvirus 8 [HHV8]) is implicated in the pathogenesis of many human malignancies including Kaposi's sarcoma (KS), multicentric Castleman's disease (MCD), and primary effusion lymphoma (PEL). KSHV infection displays two alternative life cycles, referred to as the latent and lytic or productive cycle. Previously, we have reported that the replication and transcription activator (RTA), a major lytic cycle transactivator, contributes to the development of KSHV latency by inducing latency-associated nuclear antigen (LANA) expression during early stages of infection by targeting RBP-Jκ, the master regulator of the Notch signaling pathway. Here, we generated a bacterial artificial chromosome (BAC) KSHV recombinant virus with a deletion of the RBP-Jκ site within the LANA promoter to evaluate the function of the RBP-Jκ cognate site in establishing primary latent infection. The results showed that genetic disruption of the RBP-Jκ binding site within the KSHV LANA promoter led to enhanced expression of the KSHV-encoded immediate early RTA, resulting in an increase in lytic replication during primary infection of human peripheral blood mononuclear cells (PBMCs). This system provides a powerful tool for use in indentifying additional cellular and viral molecules involved in LANA-mediated latency maintenance during the early stages of KSHV infection.
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- 2011
8. Bub1 and CENP-F Can Contribute to Kaposi's Sarcoma-Associated Herpesvirus Genome Persistence by Targeting LANA to Kinetochores
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Qiliang Cai, Jie Lu, Bingyi Xiao, Rajeev Kaul, Erle S. Robertson, Subhash C. Verma, and Abhik Saha
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Cell division ,Chromosomal Proteins, Non-Histone ,viruses ,Immunology ,Cellular Response to Infection ,Mitosis ,Genome, Viral ,In Vitro Techniques ,Protein Serine-Threonine Kinases ,Biology ,medicine.disease_cause ,Models, Biological ,Microbiology ,Genome ,Cell Line ,Small hairpin RNA ,Virology ,Host chromosome ,Protein Interaction Mapping ,medicine ,Humans ,Gammaherpesvirinae ,RNA, Small Interfering ,Kaposi's sarcoma-associated herpesvirus ,Kinetochores ,Antigens, Viral ,Base Sequence ,Kinetochore ,Microfilament Proteins ,Nuclear Proteins ,virus diseases ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Molecular biology ,Gene Knockdown Techniques ,Insect Science ,Herpesvirus 8, Human ,Host-Pathogen Interactions ,Plasmids - Abstract
The latency-associated nuclear antigen (LANA) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) is critical for segregation of viral episomes to progeny nuclei and allows for maintenance of the viral genome in newly divided daughter cells. LANA binds to KSHV terminal repeat (TR) DNA and simultaneously associates with chromatin-bound cellular proteins. This process tethers the viral episomes to host chromosomes. However, the mechanism of tethering is complex and involves multiple protein-protein interactions. Our previous proteomics studies which showed the association of LANA with centromeric protein F (CENP-F) prompted us to further study whether LANA targets centromeric proteins for persistence of KSHV episomes during cell division. Here we show that LANA colocalized with CENP-F as speckles, some of which are paired at centromeric regions of a subset of chromosomes in KSHV-infected JSC-1 cells. We also confirm that both the amino and carboxy termini of LANA can bind to CENP-F. Moreover, LANA associated with another kinetochore protein, Bub1 (budding uninhibited by benzimidazole 1), which is known to form a complex with CENP-F. Importantly, we demonstrated the dynamic association of LANA and Bub1/CENP-F and the colocalization between Bub1, LANA, and the KSHV episome tethered to the host chromosome using fluorescence in situ hybridization (FISH). Knockdown of Bub1 expression by lentivirus-delivered short hairpin RNA (shRNA) dramatically reduced the number of KSHV genome copies, whereas no dramatic effect was seen with CENP-F knockdown. Therefore, the interaction between LANA and the kinetochore proteins CENP-F and Bub1 is important for KSHV genome tethering and its segregation to new daughter cells, with Bub1 potentially playing a more critical role in the long-term persistence of the viral genome in the infected cell.
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- 2010
9. Epstein-Barr Virus Nuclear Antigen 3C Interacts with and Enhances the Stability of the c-Myc Oncoprotein
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Bharat G. Bajaj, Qiliang Cai, Masanao Murakami, Erle S. Robertson, Ke Lan, and Subhash C. Verma
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Herpesvirus 4, Human ,Transcription, Genetic ,Blotting, Western ,Immunology ,Plasma protein binding ,Biology ,Microbiology ,Cell Line ,Proto-Oncogene Proteins c-myc ,Transcription (biology) ,Virology ,Protein Interaction Mapping ,Coactivator ,Humans ,Immunoprecipitation ,RNA, Messenger ,Antigens, Viral ,S-Phase Kinase-Associated Proteins ,Binding Sites ,Promoter ,Cell cycle ,Virus-Cell Interactions ,Epstein-Barr Virus Nuclear Antigens ,Insect Science ,Ubiquitin ligase complex ,Cancer research ,Protein Binding ,Binding domain - Abstract
Epstein-Barr virus (EBV) was the first human DNA virus to be associated with cancer. Its oncogenic potential was further demonstrated by its ability to transform primary B lymphocytes in vitro. EBV nuclear antigen 3C (EBNA3C) is one of a small subset of latent antigens critical for the transformation of human primary B lymphocytes. Although EBNA3C has been shown to modulate several cellular functions, additional targets involved in cellular transformation remain to be explored. EBNA3C can recruit key components of the SCFSkp2ubiquitin ligase complex. In this report, we show that EBNA3C residues 130 to 190, previously shown to bind to the SCFSkp2complex, also can strongly associate with the c-Myc oncoprotein. Additionally, the interaction of EBNA3C with c-Myc was mapped to the region of c-Myc that includes the highly conserved Skp2 binding domain. Skp2 has been shown to regulate c-Myc stability and also has been shown to function as a coactivator of transcription for c-Myc target genes. We now show that the EBV latent oncoprotein EBNA3C can stabilize c-Myc and that the recruitment of both c-Myc and its cofactor Skp2 to c-Myc-dependent promoters can enhance c-Myc-dependent transcription. This same region of EBNA3C also recruits and modulates the activity of retinoblastoma and p27, both major regulators of the mammalian cell cycle. The inclusion of c-Myc in the group of cellular targets modulated by this domain further accentuates the importance of these critical residues of EBNA3C in bypassing the cell cycle checkpoints.
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- 2008
10. A Potential α-Helix Motif in the Amino Terminus of LANA Encoded by Kaposi's Sarcoma-Associated Herpesvirus Is Critical for Nuclear Accumulation of HIF-1α in Normoxia
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Masanao Murakami, Qiliang Cai, Erle S. Robertson, and Huaxin Si
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Small interfering RNA ,viruses ,Amino Acid Motifs ,Immunology ,medicine.disease_cause ,Microbiology ,Protein Structure, Secondary ,Ubiquitin ,Virology ,medicine ,Humans ,Gammaherpesvirinae ,Nuclear protein ,Kaposi's sarcoma-associated herpesvirus ,Promoter Regions, Genetic ,Antigens, Viral ,Sarcoma, Kaposi ,Cell Line, Transformed ,Cell Nucleus ,biology ,HEK 293 cells ,Nuclear Proteins ,virus diseases ,biochemical phenomena, metabolism, and nutrition ,Hypoxia-Inducible Factor 1, alpha Subunit ,biology.organism_classification ,medicine.disease ,Virus-Cell Interactions ,Protein Structure, Tertiary ,Cell biology ,Cell nucleus ,medicine.anatomical_structure ,Insect Science ,Herpesvirus 8, Human ,biology.protein ,Primary effusion lymphoma - Abstract
Hypoxia-inducible factor 1 (HIF-1) is a ubiquitously expressed transcriptional regulator involved in induction of numerous genes associated with angiogenesis and tumor growth. Kaposi's sarcoma, associated with increased angiogenesis, is a highly vascularized, endothelial cell-derived tumor. Previously, we have shown that the latency-associated nuclear antigen (LANA) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) targets the HIF-1α suppressors von Hippel-Lindau protein and p53 for degradation via its suppressor of cytokine signaling-box motif, which recruits the EC 5 S ubiquitin complex. Here we further show that HIF-1α was aberrantly accumulated in KSHV latently infected primary effusion lymphoma (PEL) cells, as well as HEK293 cells infected with KSHV, and also show that a potential α-helical amino-terminal domain of LANA was important for HIF-1α nuclear accumulation in normoxic conditions. Moreover, we have now determined that this association was dependent on the residues 46 to 89 of LANA and the oxygen-dependent degradation domain of HIF-1α. Introduction of specific small interfering RNA against LANA into PEL cells also resulted in a diminished nuclear accumulation of HIF-1α. Therefore, these data show that LANA can function not only as an inhibitor of HIF-1α suppressor proteins but can also induce nuclear accumulation of HIF-1α during KSHV latent infection.
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- 2007
11. Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Inhibits Major Histocompatibility Complex Class II Expression by Disrupting Enhanceosome Assembly through Binding with the Regulatory Factor X Complex
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Shanthan Challa, Pravinkumar Purushothaman, Qiliang Cai, Suhani Thakker, Subhash C. Verma, and Namrata Gupta
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RFXANK ,viruses ,Immunology ,Antigen presentation ,Genes, MHC Class II ,Down-Regulation ,chemical and pharmacologic phenomena ,HLA-DR alpha-Chains ,Regulatory Factor X Transcription Factors ,Biology ,Adaptive Immunity ,medicine.disease_cause ,Microbiology ,Enhanceosome ,Virology ,Cell Line, Tumor ,CIITA ,medicine ,Humans ,Kaposi's sarcoma-associated herpesvirus ,Promoter Regions, Genetic ,Transcription factor ,Antigens, Viral ,Antigen Presentation ,Histocompatibility Antigens Class II ,Nuclear Proteins ,biochemical phenomena, metabolism, and nutrition ,Cell biology ,Virus-Cell Interactions ,DNA-Binding Proteins ,HEK293 Cells ,Insect Science ,Herpesvirus 8, Human ,Host-Pathogen Interactions ,Trans-Activators ,RFX5 ,Chromatin immunoprecipitation ,Protein Binding ,Transcription Factors - Abstract
Major histocompatibility complex class II (MHC-II) molecules play a central role in adaptive antiviral immunity by presenting viral peptides to CD4 + T cells. Due to their key role in adaptive immunity, many viruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), have evolved multiple strategies to inhibit the MHC-II antigen presentation pathway. The expression of MHC-II, which is controlled mainly at the level of transcription, is strictly dependent upon the binding of the class II transactivator (CIITA) to the highly conserved promoters of all MHC-II genes. The recruitment of CIITA to MHC-II promoters requires its direct interactions with a preassembled MHC-II enhanceosome consisting of cyclic AMP response element-binding protein (CREB) and nuclear factor Y (NF-Y) complex and regulatory factor X (RFX) complex proteins. Here, we show that KSHV-encoded latency-associated nuclear antigen (LANA) disrupts the association of CIITA with the MHC-II enhanceosome by binding to the components of the RFX complex. Our data show that LANA is capable of binding to all three components of the RFX complex, RFX-associated protein (RFXAP), RFX5, and RFX-associated ankyrin-containing protein (RFXANK), in vivo but binds more strongly with the RFXAP component in in vitro binding assays. Levels of MHC-II proteins were significantly reduced in KSHV-infected as well as LANA-expressing B cells. Additionally, the expression of LANA in a luciferase promoter reporter assay showed reduced HLA-DRA promoter activity in a dose-dependent manner. Chromatin immunoprecipitation assays showed that LANA binds to the MHC-II promoter along with RFX proteins and that the overexpression of LANA disrupts the association of CIITA with the MHC-II promoter. These assays led to the conclusion that the interaction of LANA with RFX proteins interferes with the recruitment of CIITA to MHC-II promoters, resulting in an inhibition of MHC-II gene expression. Thus, the data presented here identify a novel mechanism used by KSHV to downregulate the expressions of MHC-II genes. IMPORTANCE Kaposi's sarcoma-associated herpesvirus is the causative agent of multiple human malignancies. It establishes a lifelong latent infection and persists in infected cells without being detected by the host's immune surveillance system. Only a limited number of viral proteins are expressed during latency, and these proteins play a significant role in suppressing both the innate and adaptive immunities of the host. Latency-associated nuclear antigen (LANA) is one of the major proteins expressed during latent infection. Here, we show that LANA blocks MHC-II gene expression to subvert the host immune system by disrupting the MHC-II enhanceosome through binding with RFX transcription factors. Therefore, this study identifies a novel mechanism utilized by KSHV LANA to deregulate MHC-II gene expression, which is critical for CD4 + T cell responses in order to escape host immune surveillance.
- Published
- 2014
12. EBNA3C-mediated regulation of aurora kinase B contributes to Epstein-Barr virus-induced B-cell proliferation through modulation of the activities of the retinoblastoma protein and apoptotic caspases
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Qiliang Cai, Jie Lu, Shuvomoy Banerjee, Abhik Saha, Mahadesh A. J. Prasad, Erle S. Robertson, and Hem Chandra Jha
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Chromatin Immunoprecipitation ,Epstein-Barr Virus Infections ,Herpesvirus 4, Human ,Immunology ,Blotting, Western ,Fluorescent Antibody Technique ,Caspase 3 ,Apoptosis ,Real-Time Polymerase Chain Reaction ,Microbiology ,Retinoblastoma Protein ,Gene Expression Regulation, Enzymologic ,Virology ,Animals ,Aurora Kinase B ,Humans ,Immunoprecipitation ,RNA, Messenger ,Kinase activity ,Phosphorylation ,RNA, Small Interfering ,Caspase ,Cell Proliferation ,Cell Nucleus ,B-Lymphocytes ,biology ,Cell growth ,Reverse Transcriptase Polymerase Chain Reaction ,Cell Cycle ,Retinoblastoma protein ,Ubiquitination ,Cell cycle ,Genome Replication and Regulation of Viral Gene Expression ,Epstein-Barr Virus Nuclear Antigens ,Insect Science ,Caspases ,biology.protein ,Cancer research - Abstract
Epstein-Barr virus (EBV) is an oncogenic gammaherpesvirus that is implicated in several human malignancies, including Burkitt's lymphoma (BL), posttransplant lymphoproliferative disease (PTLD), nasopharyngeal carcinoma (NPC), and AIDS-associated lymphomas. Epstein-Barr nuclear antigen 3C (EBNA3C), one of the essential EBV latent antigens, can induce mammalian cell cycle progression through its interaction with cell cycle regulators. Aurora kinase B (AK-B) is important for cell division, and deregulation of AK-B is associated with aneuploidy, incomplete mitotic exit, and cell death. Our present study shows that EBNA3C contributes to upregulation of AK-B transcript levels by enhancing the activity of its promoter. Further, EBNA3C also increased the stability of the AK-B protein, and the presence of EBNA3C leads to reduced ubiquitination of AK-B. Importantly, EBNA3C in association with wild-type AK-B but not with its kinase-dead mutant led to enhanced cell proliferation, and AK-B knockdown can induce nuclear blebbing and cell death. This phenomenon was rescued in the presence of EBNA3C. Knockdown of AK-B resulted in activation of caspase 3 and caspase 9, along with poly(ADP-ribose) polymerase 1 (PARP1) cleavage, which is known to be an important contributor to apoptotic signaling. Importantly, EBNA3C failed to stabilize the kinase-dead mutant of AK-B compared to wild-type AK-B, which suggests a role for the kinase domain in AK-B stabilization and downstream phosphorylation of the cell cycle regulator retinoblastoma protein (Rb). This study demonstrates the functional relevance of AK-B kinase activity in EBNA3C-regulated B-cell proliferation and apoptosis.
- Published
- 2013
13. Kaposi's sarcoma-associated herpesvirus inhibits interleukin-4-mediated STAT6 phosphorylation to regulate apoptosis and maintain latency
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Ji-Young Choi, Subhash C. Verma, Michelle Ma, Erle S. Robertson, and Qiliang Cai
- Subjects
medicine.medical_treatment ,viruses ,Immunology ,Apoptosis ,medicine.disease_cause ,Lymphocyte Activation ,Microbiology ,Cell Line ,Immune system ,Virology ,Virus latency ,medicine ,Gammaherpesvirinae ,Humans ,Kaposi's sarcoma-associated herpesvirus ,Phosphorylation ,Interleukin 4 ,Cell Proliferation ,B-Lymphocytes ,biology ,virus diseases ,Herpesviridae Infections ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,medicine.disease ,Virus Latency ,Cytokine ,Insect Science ,Herpesvirus 8, Human ,Cancer research ,Pathogenesis and Immunity ,Primary effusion lymphoma ,Interleukin-4 ,Signal transduction ,STAT6 Transcription Factor - Abstract
Cytokine-mediated JAK/STAT signaling controls numerous important biologic responses like immune function, cellular growth, and differentiation. Inappropriate activation of this signaling pathway is associated with a range of malignancies. Kaposi's sarcoma-associated herpesvirus (KSHV) is the infectious viral agent associated with Kaposi's sarcoma and may also contribute to B-cell disorders, which include primary effusion lymphoma (PEL) and multicentric Castleman's disease. However, regulation of cytokine-mediated lymphocytic immune response by KSHV is not fully understood. In this report, we demonstrate that KSHV suppresses the interleukin-4 (IL-4)-stimulated immune response of B-lymphocyte activation and cell proliferation. Moreover, we show that the latency-associated nuclear antigen (LANA) encoded by KSHV is essential for viral blocking of IL-4-induced signaling. LANA reduces phosphorylation of the signal transducers and activators of transcription 6 (STAT6) on Y-641 and concomitantly its DNA binding ability. Importantly, knockdown of endogenous STAT6 dramatically increases the sensitivity of PEL cells to low-serum stress or chemical-mediated cellular apoptosis and reactivation of KSHV from latent replication. Thus, these findings suggest that the IL-4/STAT6 signaling network is precisely controlled by KSHV for survival, maintenance of latency, and suppression of the host cytokine immune response of the virus-infected cells.
- Published
- 2010
14. Latency-associated nuclear antigen of Kaposi's sarcoma-associated herpesvirus (KSHV) upregulates survivin expression in KSHV-Associated B-lymphoma cells and contributes to their proliferation
- Author
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Erle S. Robertson, Masanao Murakami, Qiliang Cai, Jie Lu, Subhash C. Verma, Bingyi Xiao, and Pankaj Kumar
- Subjects
Lymphoma, B-Cell ,Sp1 Transcription Factor ,viruses ,Survivin ,Immunology ,medicine.disease_cause ,Microbiology ,Cell Line ,Inhibitor of Apoptosis Proteins ,Small hairpin RNA ,Downregulation and upregulation ,Virology ,medicine ,Gammaherpesvirinae ,Humans ,Kaposi's sarcoma-associated herpesvirus ,Promoter Regions, Genetic ,Author Correction ,neoplasms ,Antigens, Viral ,Sarcoma, Kaposi ,Cell Proliferation ,Regulation of gene expression ,Gene knockdown ,biology ,HEK 293 cells ,virus diseases ,Nuclear Proteins ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Virus-Cell Interactions ,Up-Regulation ,Gene Expression Regulation ,Insect Science ,Herpesvirus 8, Human ,Cancer research ,Tumor Suppressor Protein p53 ,Microtubule-Associated Proteins ,Protein Binding - Abstract
Survivin is a master regulator of cell proliferation and cell viability and is highly expressed in most human tumors. The molecular network linked to survivin expression in tumors has not been completely elucidated. In this study, we show that latency-associated nuclear antigen (LANA), a multifunctional protein of Kaposi's sarcoma-associated herpesvirus (KSHV) that is found in Kaposi's sarcoma tumors, upregulates survivin expression and increases the proliferation of KSHV-infected B cells. Analysis of pathway-specific gene arrays showed that survivin expression was highly upregulated in BJAB cells expressing LANA. The mRNA levels of survivin were also upregulated in HEK 293 and BJAB cells expressing LANA. Similarly, protein levels of survivin were significantly higher in LANA-expressing, as well as KSHV-infected, cells. Survivin promoter activity assays identified GC/Sp1 and p53 cis -acting elements within the core promoter region as being important for LANA activity. Gel mobility shift assays revealed that LANA forms a complex with Sp1 or Sp1-like proteins bound to the GC/Sp1 box of the survivin promoter. In addition, a LANA/p53 complex bound to the p53 cis -acting element within the survivin promoter, indicating that upregulation of survivin expression can also occur through suppression of p53 function. Furthermore, immunohistochemistry analyses revealed that survivin expression was upregulated in KSHV-associated Kaposi's sarcoma tissue, suggesting that LANA plays an important role in the upregulation of survivin expression in KSHV-infected endothelial cells. Knockdown of survivin expression by lentivirus-delivered small hairpin RNA resulted in loss of cell proliferation in KSHV-infected cells. Therefore, upregulation of survivin expression in KSHV-associated human cells contributes to their proliferation.
- Published
- 2009
15. Latency-associated nuclear antigen of Kaposi's sarcoma-associated herpesvirus recruits uracil DNA glycosylase 2 at the terminal repeats and is important for latent persistence of the virus
- Author
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Bharat G. Bajaj, Subhash C. Verma, Huaxin Si, Qiliang Cai, Todd Seelhammer, and Erle S. Robertson
- Subjects
Lymphoma ,viruses ,Immunology ,Biology ,medicine.disease_cause ,Microbiology ,Models, Biological ,Cell Line ,DNA Glycosylases ,chemistry.chemical_compound ,Mice ,Virology ,Virus latency ,Protein Interaction Mapping ,medicine ,Animals ,Humans ,Immunoprecipitation ,Lymphocytes ,Kaposi's sarcoma-associated herpesvirus ,Antigens, Viral ,Cells, Cultured ,DNA replication ,Terminal Repeat Sequences ,virus diseases ,Nuclear Proteins ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,Molecular biology ,Virus Latency ,Genome Replication and Regulation of Viral Gene Expression ,chemistry ,DNA glycosylase ,Insect Science ,Uracil-DNA glycosylase ,Herpesvirus 8, Human ,Primary effusion lymphoma ,Cytosine ,DNA ,Protein Binding - Abstract
Latency-associated nuclear antigen (LANA) of KSHV is expressed in all forms of Kaposi's sarcoma-associated herpesvirus (KSHV)-mediated tumors and is important for TR-mediated replication and persistence of the virus. LANA does not exhibit any enzymatic activity by itself but is critical for replication and maintenance of the viral genome. To identify LANA binding proteins, we used a LANA binding sequence 1 DNA affinity column and determined the identities of a number of proteins associated with LANA. One of the identified proteins was uracil DNA glycosylase 2 (UNG2). UNG2 is important for removing uracil residues yielded after either misincorporation of dUTP during replication or deamination of cytosine. The specificity of the ′LANA-UNG2 interaction was confirmed by using a scrambled DNA sequence affinity column. Interaction of LANA and UNG2 was further confirmed by in vitro binding and coimmunoprecipitation assays. Colocalization of these proteins was also detected in primary effusion lymphoma (PEL) cells, as well as in a cotransfected KSHV-negative cell line. UNG2 binds to the carboxyl terminus of LANA and retains its enzymatic activity in the complex. However, no major effect on TR-mediated DNA replication was observed when a UNG2-deficient (UNG −/− ) cell line was used. Infection of UNG −/− and wild-type mouse embryonic fibroblasts with KSHV did not reveal any difference; however, UNG −/− cells produced a significantly reduced number of virion particles after induction. Interestingly, depletion of UNG2 in PEL cells with short hairpin RNA reduced the number of viral genome copies and produced infection-deficient virus.
- Published
- 2006
16. Kaposi's sarcoma-associated herpesvirus latent protein LANA interacts with HIF-1 alpha to upregulate RTA expression during hypoxia: Latency control under low oxygen conditions
- Author
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Huaxin Si, Erle S. Robertson, Ke Lan, Doug Lin, Subhash C. Verma, and Qiliang Cai
- Subjects
Gene Expression Regulation, Viral ,Transcription, Genetic ,viruses ,Immunology ,Biology ,medicine.disease_cause ,Response Elements ,Virus Replication ,Microbiology ,Immediate early protein ,Immediate-Early Proteins ,Viral Proteins ,Virology ,Gene expression ,medicine ,Gammaherpesvirinae ,Humans ,Anaerobiosis ,RNA, Messenger ,Kaposi's sarcoma-associated herpesvirus ,Nuclear protein ,Hypoxia ,Promoter Regions, Genetic ,Antigens, Viral ,virus diseases ,Nuclear Proteins ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,medicine.disease ,Hypoxia-Inducible Factor 1, alpha Subunit ,Molecular biology ,Virus-Cell Interactions ,Oxygen ,Lytic cycle ,Regulatory sequence ,Insect Science ,Herpesvirus 8, Human ,Trans-Activators ,Primary effusion lymphoma - Abstract
Hypoxia can induce lytic replication of Kaposi's sarcoma-associated herpesvirus (KSHV) in primary effusion lymphoma (PEL) cells. However, the molecular mechanism of lytic reactivation of KSHV by hypoxia remains unclear. Here we show that the latency-associated nuclear antigen (LANA), which plays a crucial role in modulating viral and cellular gene expression, directly associated with a low oxygen responder, hypoxia-inducible factor-1α (HIF-1α). LANA enhanced not only the transcriptional activities of HIF-1α but also its mRNA level. Coimmunoprecipitation and immunofluorescence studies documented a physical interaction between LANA and HIF-1α in transiently transfected 293T cells as well as in PEL cell lines during hypoxia. Through sequence analysis, several putative hypoxia response elements (HRE-1 to -6) were identified in the essential lytic geneRtapromoter. Reporter assays showed that HRE-2 (−1130 to −1123) and HRE-5 and HRE-6 (+234 to +241 and +812 to +820, respectively, within the intron sequence) were necessary and sufficient for the LANA-mediated HIF-1α response. Electrophoretic mobility shift assays showed HIF-1α-dependent binding of a LANA protein complex specifically to the HRE-2, -5, and -6 motifs within the promoter regulatory sequences. This study demonstrates that hypoxia-induced KSHV lytic replication is mediated at least in part through cooperation of HIF-1α with LANA bound to the HRE motifs of theRtapromoter.
- Published
- 2006
17. Kaposi's Sarcoma-Associated Herpesvirus Inhibits Interleukin-4-Mediated STAT6 Phosphorylation To Regulate Apoptosis and Maintain Latency.
- Author
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Qiliang Cai, Verma, Subhash C., Ji-Young Choi, Ma, Michelle, and Robertson, Erle S.
- Subjects
- *
KAPOSI'S sarcoma , *AIDS complications , *HERPESVIRUS diseases , *INTERLEUKIN-4 , *APOPTOSIS , *CELL proliferation , *IMMUNE response - Abstract
Cytokine-mediated JAK/STAT signaling controls numerous important biologic responses like immune function, cellular growth, and differentiation. Inappropriate activation of this signaling pathway is associated with a range of malignancies. Kaposi's sarcoma-associated herpesvirus (KSHV) is the infectious viral agent associated with Kaposi's sarcoma and may also contribute to B-cell disorders, which include primary effusion lymphoma (PEL) and multicentric Castleman's disease. However, regulation of cytokine-mediated lymphocytic immune response by KSHV is not fully understood. In this report, we demonstrate that KSHV suppresses the interleukin-4 (IL-4)-stimulated immune response of B-lymphocyte activation and cell proliferation. Moreover, we show that the latency-associated nuclear antigen (LANA) encoded by KSHV is essential for viral blocking of IL-4-induced signaling. LANA reduces phosphorylation of the signal transducers and activators of transcription 6 (STAT6) on Y-641 and concomitantly its DNA binding ability. Importantly, knockdown of endogenous STAT6 dramatically increases the sensitivity of PEL cells to low-serum stress or chemical-mediated cellular apoptosis and reactivation of KSHV from latent replication. Thus, these findings suggest that the IL-4/STAT6 signaling network is precisely controlled by KSHV for survival, maintenance of latency, and suppression of the host cytokine immune response of the virus-infected cells. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
18. Degradation of TRIM32 is induced by RTA for Kaposi’s sarcoma-associated herpesvirus lytic replication.
- Author
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Yulin Zhang, Zhongwei Dong, Feng Gu, Yifei Xu, Ying Li, Wen Sun, Wutian Rao, Shujuan Du, Caixia Zhu, Yuyan Wang, Fang Wei, and Qiliang Cai
- Subjects
- *
KAPOSI'S sarcoma-associated herpesvirus , *KAPOSI'S sarcoma , *VIRUS diseases , *VIRUS reactivation - Abstract
TRIM32 is often aberrantly expressed in many types of cancers. Kaposi’s sarcoma-associated herpesvirus (KSHV) is linked with several human malignancies, including Kaposi’s sarcoma and primary effusion lymphomas (PELs). Increasing evidence has demonstrated the crucial role of KSHV lytic replication in viral tumorigenesis. However, the role of TRIM32 in herpesvirus lytic replication remains unclear. Here, we reveal that the expression of TRIM32 is upregulated by KSHV in latency, and reactivation of KSHV lytic replication leads to the inhibition of TRIM32 in PEL cells. Strikingly, RTA, the master regulator of lytic replication, interacts with TRIM32 and dramatically promotes TRIM32 for degradation via the proteasome systems. Inhibition of TRIM32 induces cell apoptosis and in turn inhibits the proliferation and colony formation of KSHV-infected PEL cells and facilitates the reactivation of KSHV lytic replication and virion production. Thus, our data imply that the degradation of TRIM32 is vital for the lytic activation of KSHV and is a potential therapeutic target for KSHV-associated cancers. IMPORTANCE TRIM32 is associated with many cancers and viral infections; however, the role of TRIM32 in viral oncogenesis remains largely unknown. In this study, we found that the expression of TRIM32 is elevated by Kaposi’s sarcoma-associated herpesvirus (KSHV) in latency, and RTA (the master regulator of lytic replication) induces TRIM32 for proteasome degradation upon viral lytic reactivation. This finding provides a potential therapeutic target for KSHV-associated cancers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
19. Broad-spectrum vaccine via combined immunization routes triggers potent immunity to SARS-CoV-2 and its variants.
- Author
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Man Xing, Yihan Wang, Xinyu Wang, Jiaojiao Liu, Weiqian Dai, Gaowei Hu, Furong He, Qian Zhao, Ying Li, Lingjin Sun, Yuyan Wang, Shujuan Du, Zhongwei Dong, Chongjie Pang, Zhidong Hu, Xiaoyan Zhang, Jianqing Xu, Qiliang Cai, and Dongming Zhou
- Subjects
- *
GENETIC vectors , *COMBINED vaccines , *SARS-CoV-2 , *B cells , *IMMUNOLOGIC memory , *T cells , *IMMUNITY , *COVID-19 vaccines - Abstract
Developing broad-spectrum vaccines and optimal vaccination strategies is crucial to controlling the COVID-19 pandemic. Here, we generated a chimpanzee adenoviral vector-based COVID-19 vaccine carrying broad-spectrum immunogens, modified full-length spike, and conserved T-cell epitopes of SARS-CoV-2, and assessed its immune response in mice through intramuscular (i.m.), intranasal (i.n.), or combined immunization routes (i.m. + i.n., or i.n. + i.m.). Compared to other vaccination strategies, the two combined regimens elicited higher neutralizing antibody (NAb) responses to all variants. Compared to i.n. + i.m. regimen, the i.m. + i.n. regimen stimulated a stronger secondary GC response, which is more pivotal to high-quality antibody production than the primary GC response. Moreover, the i.m. + i.n. regimen was adept at mediating systemic cellular immunity, while the i.n. + i .m. regimen tended to elicit lung tissue-resident memory T (TRM) cell responses. Overall, the two combined regimens induced comprehensive but distinct immune responses consisting of lgA, lgG, NAbs, GC B cells, long-lived plasma cells, TRM cells, and systemic memory T cells, which conferred complete protection against BA.2 infection in hACE2 transgenic mice, and warranted further investigation as potential universal vaccination strategies. IMPORTANCE The development of broad-spectrum SARS-CoV-2 vaccines will reduce the global economic and public health stress from the COVID-19 pandemic. The use of conserved T-cell epitopes in combination with spike antigen that induce humoral and cellular immune responses simultaneously may be a promising strategy to further enhance the broad spectrum of COVID-19 vaccine candidates. Moreover, this research suggests that the combined vaccination strategies have the ability to induce both effective systemic and mucosal immunity, which may represent promising strategies for maximizing the protective efficacy of respiratory virus vaccines. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
20. A Potential α-Helix Motif in the Amino Terminus of LANA Encoded by Kaposi's Sarcoma-Associated Herpesvirus Is Critical for Nuclear Accumulation of HIF-1α in Normoxia.
- Author
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Qiliang Cai, Murakami, Masanao, Huaxin Si, and Robertson, Erle S.
- Subjects
- *
KAPOSI'S sarcoma , *HERPESVIRUSES , *HYPOXEMIA , *GENETIC transcription regulation , *NEOVASCULARIZATION , *VIRAL proteins - Abstract
Hypoxia-inducible factor 1 (HIF-1) is a ubiquitously expressed transcriptional regulator involved in induction of numerous genes associated with angiogenesis and tumor growth. Kaposi's sarcoma, associated with increased angiogenesis, is a highly vascularized, endothelial cell-derived tumor. Previously, we have shown that the latency-associated nuclear antigen (LANA) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) targets the HIF-1 α suppressors von Hippel-Lindau protein and p53 for degradation via its suppressor of cytokine signaling-box motif, which recruits the EC5S ubiquitin complex. Here we further show that HIF-1 α was aberrantly accumulated in KSHV latently infected primary effusion lymphoma (PEL) cells, as well as HEK293 cells infected with KSHV, and also show that a potential α-helical amino-terminal domain of LANA was important for HIF-1 α nuclear accumulation in normoxic conditions. Moreover, we have now determined that this association was dependent on the residues 46 to 89 of LANA and the oxygen-dependent degradation domain of HIF-1 α. Introduction of specific small interfering RNA against LANA into PEL cells also resulted in a diminished nuclear accumulation of HIF-1 α. Therefore, these data show that LANA can function not only as an inhibitor of HIF-1 α suppressor proteins but can also induce nuclear accumulation of HIF-1 α during KSHV latent infection. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
21. Kaposi's Sarcoma-Associated Herpesvirus Latent Protein LANA Interacts with HIF-1α To Upregulate RTA Expression during Hypoxia: Latency Control under Low Oxygen Conditions.
- Author
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Qiliang Cai, Ke Lan, Verma, Subhash C., Huaxin Si, Doug Lin, and Robertson, Erle S.
- Subjects
- *
HYPOXEMIA , *KAPOSI'S sarcoma , *SARCOMA , *LYMPHOMAS , *ANTIGENS - Abstract
Hypoxia can induce lytic replication of Kaposi's sarcoma-associated herpesvirus (KSHV) in primary effusion lymphoma (PEL) cells. However, the molecular mechanism of lytic reactivation of KSHV by hypoxia remains unclear. Here we show that the latency-associated nuclear antigen (LANA), which plays a crucial role in modulating viral and cellular gene expression, directly associated with a low oxygen responder, hypoxia-inducible factor-1α (HIF-1α). LANA enhanced not only the transcriptional activities of HIF-1α but also its mRNA level. Coimmunoprecipitation and immunofluorescence studies documented a physical interaction between LANA and HIF-1α in transiently transfected 293T cells as well as in PEL cell lines during hypoxia. Through sequence analysis, several putative hypoxia response elements (HRE-1 to -6) were identified in the essential lytic gene Rta promoter. Reporter assays showed that HRE-2 (-1130 to -1123) and HRE-5 and HRE-6 (+234 to +241 and +812 to +820, respectively, within the intron sequence) were necessary and sufficient for the LANA-mediated HIF-1α response. Electrophoretic mobility shift assays showed HIF-1α-dependent binding of a LANA protein complex specifically to the HRE-2, -5, and -6 motifs within the promoter regulatory sequences. This study demonstrates that hypoxia-induced KSHV lytic replication is mediated at least in part through cooperation of HIF-1α with LANA bound to the HRE motifs of the Rta promoter. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
22. A System Based on Novel Parainfluenza Virus PIV5-L for Efficient Gene Delivery of B-Lymphoma Cells.
- Author
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Xiaoqing Liu, Lilan Zheng, Ting Wang, Ying Li, Bingbing Wu, Shujuan Du, Qing Zhu, Caixia Zhu, Yuyan Wang, Rong Zhang, Fang Wei, and Qiliang Cai
- Subjects
- *
PARAINFLUENZA viruses , *KAPOSI'S sarcoma-associated herpesvirus , *GREEN fluorescent protein , *VIRUS-like particles , *GENE expression - Abstract
Aggressive B-cell lymphoma is one of the most common types of blood malignancy. Robust delivery of genes of interest into target cells, long-term gene expression, and minimal risk of secondary effects are highly desirable for translational medicine including gene therapy and studies on gene function. However, efficient gene delivery into viral or nonviral B-lymphoma cells remains a challenge. Here, we report a strategy for inducing foreign gene expression in B-lymphoma cells by using a vector based on the novel parainfluenza virus PIV5-L (a strain isolated from B cells) that enabled us to study and control the function of a gene product within B-lymphoma cells. Using enhanced green fluorescent protein (eGFP) as a reporter, we successfully rescued PIV5-L and established a one-step system to generate PIV5-L virus-like particles (L-VLPs) with efficient delivery into a broad spectrum of susceptible B-lymphoma cell lines, including Epstein-Barr virus (EBV)- or Kaposi’s sarcoma-associated herpesvirus (KSHV)-transformed B-lymphoblastoid cells. Similar to lentiviral vector, the L-VLP highly expressed exogenous genes and remained stable for long periods without obvious negative effects on cell viability. Taken together, these data demonstrate that the PIV5-L-based system provides a potential new strategy for the delivery of desirable genes and the treatment of cancer. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
23. Lactic Acid Downregulates Viral MicroRNA To Promote Epstein-Barr Virus-Immortalized B Lymphoblastic Cell Adhesion and Growth.
- Author
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Xiaohui Mo, Fang Wei, Yin Tong, Ling Ding, Qing Zhu, Shujuan Du, Fei Tan, Caixia Zhu, Yuyan Wang, Qian Yu, Yeqiang Liu, Robertson, Erle S., Zhenghong Yuan, and Qiliang Cai
- Subjects
- *
LACTIC acid , *B cells , *RNA , *EPSTEIN-Barr virus , *DEHYDROGENASES - Abstract
High plasma lactate is associated with poor prognosis of many malignancies, but its role in virally mediated cancer progression and underlying molecular mechanisms are unclear. Epstein-Barr virus (EBV), the first human oncogenic virus, causes several cancers, including B-cell lymphoma. Here, we report that lactate dehydrogenase A (LDH-A) expression and lactate production are elevated in EBV-immortalized B lymphoblastic cells, and lactic acid (LA; acidic lactate) at low concentration triggers EBV-infected B-cell adhesion, morphological changes and proliferation in vitro and in vivo. Moreover, LA-induced responses of EBV-infected B cells uniquely occurs in viral latency type III, and it is dramatically associated with the inhibition of global viral microRNAs, particularly the miR-BHRF1 cluster, and the high expression of SMAD3, JUN, and COL1A genes. The introduction of miR-BHRF1-1 blocks the LA-induced effects of EBV-infected B cells. Thus, this may be a novel mechanism to explain EBV-immortalized B lymphoblastic cell malignancy in an LA microenvironment. IMPORTANCE The tumor microenvironment is complicated, and lactate, which is created by cell metabolism, contributes to an acidic microenvironment that facilitates cancer progression. However, how LA operates in virus-associated cancers is unclear. Thus, we studied how EBV (the first tumor virus identified in humans; it is associated with many cancers) upregulates the expression of LDH-A and lactate production in B lymphoma cells. Elevated LA induces adhesion and the growth of EBVinfected B cells by inhibiting viral microRNA transcription. Thus, we offer a novel understanding of how EBV utilizes an acidic microenvironment to promote cancer development. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
24. The Single RBP-JK Site within the LANA Promoter Is Crucial for Establishing Kaposi's Sarcoma-Associated Herpesvirus Latency during Primary Infection.
- Author
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Jie Lu, Verma, Subhash C., Qiliang Cai, and Robertson, Erle S.
- Subjects
- *
KAPOSI'S sarcoma , *LATENCY-associated nuclear antigen , *TUMORS , *RECOMBINANT viruses , *HERPESVIRUSES , *CASTLEMAN'S disease - Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV; or human herpesvirus 8 [HHV8]) is implicated in the pathogenesis of many human malignancies including Kaposi's sarcoma (KS), multicentric Castleman's disease (MCD), and primary effusion lymphoma (PEL). KSHV infection displays two alternative life cycles, referred to as the latent and lytic or productive cycle. Previously, we have reported that the replication and transcription activator (RTA), a major lytic cycle transactivator, contributes to the development of KSHV latency by inducing latency-associated nuclear antigen (LANA) expression during early stages of infection by targeting RBP-Jκ, the master regulator of the Notch signaling pathway. Here, we generated a bacterial artificial chromosome (BAC) KSHV recombinant virus with a deletion of the RBP-Jκ site within the LANA promoter to evaluate the function of the RBP-Jκ cognate site in establishing primary latent infection. The results showed that genetic disruption of the RBP-Jκ binding site within the KSHV LANA promoter led to enhanced expression of the KSHV-encoded immediate early RTA, resulting in an increase in lytic replication during primary infection of human peripheral blood mononuclear cells (PBMCs). This system provides a powerful tool for use in indentifying additional cellular and viral molecules involved in LANA-mediated latency maintenance during the early stages of KSHV infection. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
25. Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Inhibits Major Histocompatibility Complex Class II Expression by Disrupting Enhanceosome Assembly through Binding with the Regulatory Factor X Complex.
- Author
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Thakker, Suhani, Purushothaman, Pravinkumar, Gupta, Namrata, Challa, Shanthan, Qiliang Cai, and Verma, Subhash C.
- Subjects
- *
T cells , *KAPOSI'S sarcoma , *NF-kappa B , *ANKYRINS , *LUCIFERASES , *CHROMATIN - Abstract
Major histocompatibility complex class II (MHC-II) molecules play a central role in adaptive antiviral immunity by presenting viral peptides to CD4+ T cells. Due to their key role in adaptive immunity, many viruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), have evolved multiple strategies to inhibit the MHC-II antigen presentation pathway. The expression of MHC-II, which is controlled mainly at the level of transcription, is strictly dependent upon the binding of the class II transactivator (CIITA) to the highly conserved promoters of all MHC-II genes. The recruitment of CIITA to MHC-II promoters requires its direct interactions with a preassembled MHC-II enhanceosome consisting of cyclic AMP response element-binding protein (CREB) and nuclear factor Y (NF-Y) complex and regulatory factor X (RFX) complex proteins. Here, we show that KSHV-encoded latency-associated nuclear antigen (LANA) disrupts the association of CIITA with the MHC-II enhanceosome by binding to the components of the RFX complex. Our data show that LANA is capable of binding to all three components of the RFX complex, RFX-associated protein (RFXAP), RFX5, and RFX-associated ankyrin-containing protein (RFXANK), in vivo but binds more strongly with the RFXAP component in in vitro binding assays. Levels of MHC-II proteins were significantly reduced in KSHV-infected as well as LANA-expressing B cells. Additionally, the expression of LANA in a luciferase promoter reporter assay showed reduced HLA-DRA promoter activity in a dose-dependent manner. Chromatin immunoprecipitation assays showed that LANA binds to the MHC-II promoter along with RFX proteins and that the overexpression of LANA disrupts the association of CIITA with the MHC-II promoter. These assays led to the conclusion that the interaction of LANA with RFX proteins interferes with the recruitment of CIITA to MHC-II promoters, resulting in an inhibition of MHC-II gene expression. Thus, the data presented here identify a novel mechanism used by KSHV to downregulate the expressions of MHC-II genes. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
26. Inhibition of KAP1 Enhances Hypoxia-Induced Kaposi's Sarcoma- Associated Herpesvirus Reactivation through RBP-Jκ.
- Author
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Liming Zhang, Caixia Zhu, Yi Guo, Fang Wei, Jie Lu, Jing Qin, Banerjee, Shuvomoy, Junwen Wang, Hong Shang, Verma, Subhash C., Zhenghong Yuan, Robertson, Erle S., and Qiliang Cai
- Subjects
- *
HYPOXIA-inducible factor 1 , *KAPOSI'S sarcoma-associated herpesvirus diseases , *LATENCY-associated nuclear antigen , *SODIUM butyrate , *PROMOTERS (Genetics) , *LYTIC cycle , *HYPOXEMIA , *RNA interference , *DISEASE risk factors - Abstract
Hypoxia-inducible factor 1α (HIF-1α) has been frequently implicated in many cancers as well as viral pathogenesis. Kaposi's sarcoma-associated herpesvirus (KSHV) is linked to several human malignancies. It can stabilize HIF-1α during latent infection and undergoes lytic replication in response to hypoxic stress. However, the mechanism by which KSHV controls its latent and lytic life cycle through the deregulation of HIF-1α is not fully understood. Our previous studies showed that the hypoxia-sensitive chromatin remodeler KAP1 was targeted by the KSHV-encoded latency-associated nuclear antigen (LANA) to repress expression of the major lytic replication and transcriptional activator (RTA). Here we further report that an RNA interferencebased knockdown of KAP1 in KSHV-infected primary effusion lymphoma (PEL) cells disrupted viral episome stability and abrogated sub-G1/G1 arrest of the cell cycle while increasing the efficiency of KSHV lytic reactivation by hypoxia or using the chemical 12-O-tetradecanoylphorbol-13-acetate (TPA) or sodium butyrate (NaB). Moreover, KSHV genome-wide screening revealed that four hypoxia-responsive clusters have a high concurrence of both RBP-Jκ and HIF-1α binding sites (RBSHRE) within the same gene promoter and are tightly associated with KAP1. Inhibition of KAP1 greatly enhanced the association of RBP-Jκ with the HIF-1α complex for driving RTA expression not only in normoxia but also in hypoxia. These results suggest that both KAP1 and the concurrence of RBS+HRE within the RTA promoter are essential for KSHV latency and hypoxia-induced lytic reactivation. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
27. EBNA3C-Mediated Regulation of Aurora Kinase B Contributes to Epstein-Barr Virus-Induced B-Cell Proliferation through Modulation of the Activities of the Retinoblastoma Protein and Apoptotic Caspases.
- Author
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Jha, Hem Chandra, Jie Lu, Saha, Abhik, Qiliang Cai, Banerjee, Shuvomoy, Prasad, Mahadesh A. J., and Robertson, Erle S.
- Subjects
- *
EPSTEIN-Barr virus , *GENETIC regulation , *AURORA kinases , *B cells , *CELL proliferation , *RETINOBLASTOMA protein , *APOPTOSIS , *CASPASES - Abstract
Epstein-Barr virus (EBV) is an oncogenic gammaherpesvirus that is implicated in several human malignancies, including Burkitt's lymphoma (BL), posttransplant lymphoproliferative disease (PTLD), nasopharyngeal carcinoma (NPC), and AIDSassociated lymphomas. Epstein-Barr nuclear antigen 3C (EBNA3C), one of the essential EBV latent antigens, can induce mammalian cell cycle progression through its interaction with cell cycle regulators. Aurora kinase B (AK-B) is important for cell division, and deregulation of AK-B is associated with aneuploidy, incomplete mitotic exit, and cell death. Our present study shows that EBNA3C contributes to upregulation of AK-B transcript levels by enhancing the activity of its promoter. Further, EBNA3C also increased the stability of the AK-B protein, and the presence of EBNA3C leads to reduced ubiquitination of AK-B. Importantly, EBNA3C in association with wild-type AK-B but not with its kinase-dead mutant led to enhanced cell proliferation, and AK-B knockdown can induce nuclear blebbing and cell death. This phenomenon was rescued in the presence of EBNA3C. Knockdown of AK-B resulted in activation of caspase 3 and caspase 9, along with poly(ADP-ribose) polymerase 1 (PARP1) cleavage, which is known to be an important contributor to apoptotic signaling. Importantly, EBNA3C failed to stabilize the kinasedead mutant of AK-B compared to wild-type AK-B, which suggests a role for the kinase domain in AK-B stabilization and downstream phosphorylation of the cell cycle regulator retinoblastoma protein (Rb). This study demonstrates the functional relevance of AK-B kinase activity in EBNA3C-regulated B-cell proliferation and apoptosis. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
28. Epstein-Barr Virus Nuclear Antigen 3C Interacts with and Enhances the Stability of the c-Myc Oncoprotein.
- Author
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Bajaj, Bharat G., Murakami, Masanao, Qiliang Cai, Verma, Subhash C., Ke Lan, and Robertson, Erle S.
- Subjects
- *
ANTIGENS , *EPSTEIN-Barr virus , *MYC proteins , *B cells , *CELL cycle - Abstract
Epstein-Barr virus (EBV) was the first human DNA virus to be associated with cancer. Its oncogenic potential was further demonstrated by its ability to transform primary B lymphocytes in vitro. EBV nuclear antigen 3C (EBNA3C) is one of a small subset of latent antigens critical for the transformation of human primary B lymphocytes. Although EBNA3C has been shown to modulate several cellular functions, additional targets involved in cellular transformation remain to be explored. EBNA3C can recruit key components of the SCFSkp2 ubiquitin ligase complex. In this report, we show that EBNA3C residues 130 to 190, previously shown to bind to the SCFSkp2 complex, also can strongly associate with the c-Myc oncoprotein. Additionally, the interaction of EBNA3C with c-Myc was mapped to the region of c-Myc that includes the highly conserved Skp2 binding domain. Skp2 has been shown to regulate c-Myc stability and also has been shown to function as a coactivator of transcription for c-Myc target genes. We now show that the EBV latent oncoprotein EBNA3C can stabilize c-Myc and that the recruitment of both c-Myc and its cofactor Skp2 to c-Myc-dependent promoters can enhance c-Myc-dependent transcription. This same region of EBNA3C also recruits and modulates the activity of retinoblastoma and p27, both major regulators of the mammalian cell cycle. The inclusion of c-Myc in the group of cellular targets modulated by this domain further accentuates the importance of these critical residues of EBNA3C in bypassing the cell cycle checkpoints. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
29. Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus (KSHV) Upregulates Survivin Expression in KSHV-Associated B-Lymphoma Cells and Contributes to Their Proliferation.
- Author
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Jie Lu, Verma, Subhash C., Murakami, Masanao, Qiliang Cai, Kumar, Pankaj, Bingyi Xiao, and Robertson, Erle S.
- Subjects
- *
IMMUNOHISTOCHEMISTRY , *KAPOSI'S sarcoma , *CELL proliferation , *CELL growth , *MESSENGER RNA , *CYSTS (Pathology) - Abstract
Survivin is a master regulator of cell proliferation and cell viability and is highly expressed in most human tumors. The molecular network linked to survivin expression in tumors has not been completely elucidated. In this study, we show that latency-associated nuclear antigen (LANA), a multifunctional protein of Kaposi's sarcoma-associated herpesvirus (KSHV) that is found in Kaposi's sarcoma tumors, upregulates survivin expression and increases the proliferation of KSHV-infected B cells. Analysis of pathway-specific gene arrays showed that survivin expression was highly upregulated in BJAB cells expressing LANA. The mRNA levels of survivin were also upregulated in HEK 293 and BJAB cells expressing LANA. Similarly, protein levels of survivin were significantly higher in LANA-expressing, as well as KSHV-infected, cells. Survivin promoter activity assays identified GC/Sp1 and p53 cis-acting elements within the core promoter region as being important for LANA activity. Gel mobility shift assays revealed that LANA forms a complex with Sp1 or Sp1-like proteins bound to the GC/Sp1 box of the survivin promoter. In addition, a LANA/p53 complex bound to the p53 cis-acting element within the survivin promoter, indicating that upregulation of survivin expression can also occur through suppression of p53 function. Furthermore, immunohistochemistry analyses revealed that survivin expression was upregulated in KSHV-associated Kaposi's sarcoma tissue, suggesting that LANA plays an important role in the upregulation of survivin expression in KSHV-infected endothelial cells. Knockdown of survivin expression by lentivirus-delivered small hairpin RNA resulted in loss of cell proliferation in KSHV-infected cells. Therefore, upregulation of survivin expression in KSHV-associated human cells contributes to their proliferation. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
30. Kaposi's Sarcoma-Associated Herpesvirus-Encoded LANA Can Interact with the Nuclear Mitotic Apparatus Protein To Regulate Genome Maintenance and Segregation.
- Author
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Huaxin Si, Verma, Subhash C., Lampson, Michael A., Qiliang Cai, and Robertson, Erle S.
- Subjects
- *
KAPOSI'S sarcoma , *GENOMES , *CHROMOSOMES , *SARCOMA , *MICROTUBULES , *MOLECULAR genetics , *GENOMICS - Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) genomes are tethered to the host chromosomes and partitioned faithfully into daughter cells with the host chromosomes. The latency-associated nuclear antigen (LANA) is important for segregation of the newly synthesized viral genomes to the daughter nuclei. Here, we report that the nuclear mitotic apparatus protein (NuMA) and LANA can associate in KSHV-infected cells. In synchronized cells, NuMA and LANA are colocalized in interphase cells and separate during mitosis at the beginning of prophase, reassociating again at the end of telophase and cytokinesis. Silencing of NuMA expression by small interfering RNA and expression of LGN and a dominant-negative of dynactin (P150-CC1), which disrupts the association of NuMA with microtubules, resulted in the loss of KSHV terminal-repeat plasmids containing the major latent origin. Thus, NuMA is required for persistence of the KSHV episomes in daughter cells. This interaction between NuMA and LANA is critical for segregation and maintenance of the KSHV episomes through a temporally controlled mechanism of binding and release during specific phases of mitosis. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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