Dataset Information

B Cell Receptor Activation and Chemical Induction Trigger Caspase-Mediated Cleavage of PIAS1 to Facilitate Epstein-Barr Virus Reactivation.

ABSTRACT: Epstein-Barr virus (EBV) in tumor cells is predominately in the latent phase, but the virus can undergo lytic reactivation in response to various stimuli. However, the cellular factors that control latency and lytic replication are poorly defined. In this study, we demonstrated that a cellular factor, PIAS1, restricts EBV lytic replication. PIAS1 depletion significantly facilitated EBV reactivation, while PIAS1 reconstitution had the opposite effect. Remarkably, we found that various lytic triggers promote caspase-dependent cleavage of PIAS1 to antagonize PIAS1-mediated restriction and that caspase inhibition suppresses EBV replication through blocking PIAS1 cleavage. We further demonstrated that a cleavage-resistant PIAS1 mutant suppresses EBV replication upon B cell receptor activation. Mechanistically, we demonstrated that PIAS1 acts as an inhibitor for transcription factors involved in lytic gene expression. Collectively, these results establish PIAS1 as a key regulator of EBV lytic replication and uncover a mechanism by which EBV exploits apoptotic caspases to antagonize PIAS1-mediated restriction.

SUBMITTER: Zhang K

PROVIDER: S-EPMC5741098 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

B Cell Receptor Activation and Chemical Induction Trigger Caspase-Mediated Cleavage of PIAS1 to Facilitate Epstein-Barr Virus Reactivation.

Zhang Kun K Lv Dong-Wen DW Lv Dong-Wen DW Li Renfeng R

Cell reports 20171201 12

Epstein-Barr virus (EBV) in tumor cells is predominately in the latent phase, but the virus can undergo lytic reactivation in response to various stimuli. However, the cellular factors that control latency and lytic replication are poorly defined. In this study, we demonstrated that a cellular factor, PIAS1, restricts EBV lytic replication. PIAS1 depletion significantly facilitated EBV reactivation, while PIAS1 reconstitution had the opposite effect. Remarkably, we found that various lytic trigg ...[more]

PMID: 29262325

Similar Datasets

Project description:Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). N-nitroso compounds, phorbols, and butyrates are chemicals found in food and herb samples collected from NPC high-risk areas. These chemicals have been reported to be risk factors contributing to the development of NPC, however, the underlying mechanism is not fully understood. We have demonstrated previously that low dose N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0.1 µg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate (SB) in enhancing EBV reactivation and genome instability in NPC cells harboring EBV. Considering that residents in NPC high-risk areas may contact regularly with these chemical carcinogens, it is vital to elucidate the relation between chemicals and EBV and their contributions to the carcinogenesis of NPC. In this study, we constructed a cell culture model to show that genome instability, alterations of cancer hallmark gene expression, and tumorigenicity were increased after recurrent EBV reactivation in NPC cells following combined treatment of TPA/SB and MNNG. NPC cells latently infected with EBV, NA, and the corresponding EBV-negative cell, NPC-TW01, were periodically treated with MNNG, TPA/SB, or TPA/SB combined with MNNG. With chemically-induced recurrent reactivation of EBV, the degree of genome instability was significantly enhanced in NA cells treated with a combination of TPA/SB and MNNG than those treated individually. The Matrigel invasiveness, as well as the tumorigenicity in mouse, was also enhanced in NA cells after recurrent EBV reactivation. Expression profile analysis by microarray indicates that many carcinogenesis-related genes were altered after recurrent EBV reactivation, and several aberrations observed in cell lines correspond to alterations in NPC lesions. These results indicate that cooperation between chemical carcinogens can enhance the reactivation of EBV and, over recurrent reactivations, lead to alteration of cancer hallmark gene expression with resultant enhancement of tumorigenesis in NPC.

Project description:UnlabelledEpstein-Barr virus (EBV) is a human gammaherpesvirus associated with a variety of tumor types. EBV can establish latency or undergo lytic replication in host cells. In general, EBV remains latent in tumors and expresses a limited repertoire of latent proteins to avoid host immune surveillance. When the lytic cycle is triggered by some as-yet-unknown form of stimulation, lytic gene expression and progeny virus production commence. Thus far, the exact mechanism of EBV latency maintenance and the in vivo triggering signal for lytic induction have yet to be elucidated. Previously, we have shown that the EBV microRNA miR-BART20-5p directly targets the immediate early genes BRLF1 and BZLF1 as well as Bcl-2-associated death promoter (BAD) in EBV-associated gastric carcinoma. In this study, we found that both mRNA and protein levels of BRLF1 and BZLF1 were suppressed in cells following BAD knockdown and increased after BAD overexpression. Progeny virus production was also downregulated by specific knockdown of BAD. Our results demonstrated that caspase-3-dependent apoptosis is a prerequisite for BAD-mediated EBV lytic cycle induction. Therefore, our data suggest that miR-BART20-5p plays an important role in latency maintenance and tumor persistence of EBV-associated gastric carcinoma by inhibiting BAD-mediated caspase-3-dependent apoptosis, which would trigger immediate early gene expression.ImportanceEBV has an ability to remain latent in host cells, including EBV-associated tumor cells hiding from immune surveillance. However, the exact molecular mechanisms of EBV latency maintenance remain poorly understood. Here, we demonstrated that miR-BART20-5p inhibited the expression of EBV immediate early genes indirectly, by suppressing BAD-induced caspase-3-dependent apoptosis, in addition to directly, as we previously reported. Our study suggests that EBV-associated tumor cells might endure apoptotic stress to some extent and remain latent with the aid of miR-BART20-5p. Blocking the expression or function of BART20-5p may expedite EBV-associated tumor cell death via immune attack and apoptosis.

Project description:Epstein-Barr virus (EBV) reactivation involves the ordered induction of approximately 90 viral genes that participate in the generation of infectious virions. Using strand-specific RNA-seq to assess the EBV transcriptome during reactivation, we found extensive bidirectional transcription extending across nearly the entire genome. In contrast, only 4% of the EBV genome is currently bidirectionally annotated. Most of the newly identified transcribed regions show little evidence of coding potential, supporting noncoding roles for most of these RNAs. Based on previous cellular long noncoding RNA size calculations, we estimate that there are likely hundreds more EBV genes expressed during reactivation than was previously known. Limited 5' and 3' rapid amplification of cDNA ends (RACE) experiments and findings of novel splicing events by RNA-seq suggest that the complexity of the viral genome during reactivation may be even greater. Further analysis of antisense transcripts at some of the EBV latency gene loci showed that they are "late" genes, they are nuclear, and they tend to localize in areas of the nucleus where others find newly synthesized viral genomes. This raises the possibility that these transcripts perform functions such as new genome processing, stabilization, organization, etc. The finding of a significantly more complex EBV transcriptome during reactivation changes our view of the viral production process from one that is facilitated and regulated almost entirely by previously identified viral proteins to a process that also involves the contribution of a wide array of virus encoded noncoding RNAs. Epstein-Barr virus (EBV) is a herpesvirus that infects the majority of the world's population, in rare cases causing serious disease such as lymphoma and gastric carcinoma. Using strand-specific RNA-seq, we have studied viral gene expression during EBV reactivation and have discovered hundreds more viral transcripts than were previously known. The finding of alternative splicing and the prevalence of overlapping transcripts indicate additional complexity. Most newly identified transcribed regions do not encode proteins but instead likely function as noncoding RNA molecules which could participate in regulating gene expression, gene splicing or even activities such as viral genome processing. These findings broaden the scope of what we need to consider to understand the viral manufacturing process. As more detailed studies are undertaken they will likely change the way we view this process as a whole.

Project description:Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). Phorbol esters, butyrates and N-nitroso compounds are known chemical carcinogens in foodstuffs and cigarettes that have been implicated as risk factors contributing to the development of NPC. We have demonstrated previously that low dose N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0.1 microg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate (SB) in enhancing EBV reactivation (Chem Biol Interact 188: 623-634). Since residents of areas with a high risk of NPC are reported to contact with these carcinogens (TPA, SB or nitrosamines) frequently, we sought to determine the consequence of repeated exposure of EBV-harboring nasopharyngeal cells to these carcinogens in a long-term, low dose, repeated manner. An NPC cell line latently infected with EBV, NA, was periodically treated with TPA/SB combined with MNNG for recurrent EBV reactivation. After 10 times of chemically-induced recurrent reactivation of EBV, the expression profile analysis indicates that many carcinogenesis-related genes were altered in recurrent reactivated NA cells when compared to the parental NA cells. The expression profile was analyzed in the recurrent EBV reactivated NA cells and the parental NA cells. The expression profile of two NA cells, NA-P10/TS-MG and NA-P1/mock, were analyzed in this study. NA-P10/TS-MG cells were subject to 10 times of repeated chemical exposure by incubating these cells periodically with TPA/SB (10 ng/ml and 1.0 mM) in combination with MNNG (0.1 microg/ml). The NA cells at the beginning of this experiment were defined as passage 0 (P0) cells. 24 h after seeding, the cells were subjected to a 24 h period of mock or chemical treatment. After this 24 hr treatment, the cells were recovered by replacing the medium with fresh (treatment-free) medium and incubation for a further 48 h. The resulting cells were defined as passage 1 (P1) cells. Cells from P1 were trypsinized and transferred and the process repeated again to obtain the P2 cells. A total of ten treatments were applied to the cells in this study. M-bM-^@M-^\NA-P10/TS-MGM-bM-^@M-^] refers to NA cells with 10 times of combined TPA/SB and MNNG (TS-MG) treatments. NA-P1/mock is mock-treated NA cells with one time of passage that was used as reference in this study. Replicates were included for each samples.

Dataset Information

B Cell Receptor Activation and Chemical Induction Trigger Caspase-Mediated Cleavage of PIAS1 to Facilitate Epstein-Barr Virus Reactivation.

Publications

B Cell Receptor Activation and Chemical Induction Trigger Caspase-Mediated Cleavage of PIAS1 to Facilitate Epstein-Barr Virus Reactivation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets