Urinary Viral Spectrum in Patients with Interstitial Cystitis/Bladder Pain Syndrome and the Clinical Efficacy of Valacyclovir Treatment.

Our previous study showed that the Epstein-Barr virus (EBV) may be the etiology for some patients with interstitial cystitis/bladder pain syndrome (IC/BPS); hence, the current study aimed to investigate the urinary viral spectrum in patients with IC/BPS and the clinical efficacy of valacyclovir. Twenty-eight patients were prospectively enrolled for valacyclovir 500 mg twice a day for 4 weeks. Urine samples were collected from IC/BPS patients and 30 controls. The primary outcome was the difference in the visual analog scale (VAS) pain score, and secondary outcomes included changes in the urinary viral spectrum and urinary inflammatory cytokine level (ClinicalTrials.gov Identifier: NCT05094414). Urinary EBV was detected in 14.2% IC/BPS patients but not in the controls. Urinary John Cunningham virus and BK virus were detected in 18 (64.3%) and 2 (7.1%) patients with IC/BPS, respectively, with similar prevalences noted for the controls. No cytomegalovirus, varicella-zoster virus, or herpes simplex virus was detected in the urine samples. The VAS pain score in patients with IC/BPS significantly decreased after 4 weeks (from 7.5 [5.52-9.0] to 5 [1.5-6.0], p = 0.0003). Urinary EBV was undetectable in any sample after valacyclovir treatment, and the decreases in urinary interleukin (IL)-1ß (from 0.66 [0.55-0.82] pg/mL to 0.58 [0.55-0.64] pg/mL, p = 0.0034), IL-8 (from 6.81 [2.38 to 29.1] pg/mL to 4.33 [1.53-11.04] pg/mL, p = 0.0361), IL-10 (from 1.06 [0.94-1.18] pg/mL to 0.92 [0.88-1.02], p = 0.0086), and tumor necrosis factor-α (from 1.61 [1.50-1.72] pg/mL to 1.50 [1.44-1.55] pg/mL, p = 0.0079) were significant. Valacyclovir could relieve bladder pain, eliminate urinary EBV, and reduce bladder inflammation.

Momordica anti-HIV protein MAP30 abrogates the Epstein-Barr virus nuclear antigen 1 dependent functions in host cells.

Originally extracted from Momordica charantia seeds, the antiviral and anti-tumor activities of Momordica anti-HIV protein MAP30 have become well known. Although MAP30 has been reported to possess antiviral activity against several human viruses, the current understanding of the MAP30-mediated antiviral response is mainly derived from the previous research work on anti-HIV herbal medicines; the mechanistic insight of its effects on other viruses remains largely unknown. In this study, we showed that both ectopically expressed and purified recombinant MAP30 (rMAP30) impeded Epstein-Barr virus Nuclear Antigen 1 (EBNA1)-mediated transcription from the viral latent replication origin. Mechanistically, in vivo and in vitro studies revealed that MAP30 caused EBNA1 to dissociate from the cognate binding sites, which disrupted downstream EBNA1-dependent viral epigenome accumulation and cell maintenance of Epstein-Barr virus (EBV)-associated neoplastic cells. Finally, mutational analysis indicated that the N-terminal ricin A homologous domain shared by ricin-like proteins was implicated in the anti-EBV response. Our study provides evidence to support that MAP30 has a unique property to combat EBV latent infection, suggesting a potential to develop this herbal protein to be an alternative medicine for EBV associated diseases.

EBV infection mediated BDNF expression is associated with bladder inflammation in interstitial cystitis/bladder pain syndrome with Hunner's lesion.

Interstitial cystitis/bladder pain syndrome with Hunner's lesion (HIC) is characterized by chronic inflammation and nerve hyperplasia; however, the pathogenesis of HIC remains a mystery. In this study, we detected both Epstein-Barr virus (EBV) latency infection genes EBNA-1 and LMP-1 and EBV lytic infection BZLF-1 and BRLF-1 expression in the HIC bladders, indicating the coexistence of EBV persistence and reactivation in the B cells in HIC bladders. Upregulation of EBV-associated inflammatory genes in HIC bladders, such as TNF-α and IL-6, suggests EBV infection is implicated in the pathogenesis of bladder inflammation. Nerve hyperplasia and upregulation of brain-derived neurotrophic factor (BDNF) were noted in the HIC bladders. Double immunochemical staining and flow cytometry revealed the origin of BDNF to be EBV-infected B cells. Inducible BDNF expression was noted in B cells upon EBV infection, but not in the T cells. A chromatin immunoprecipitation study revealed BDNF transcription could be promoted by cooperation between EBV nuclear antigens, chromatin modifiers, and B-cell-specific transcription. Knockdown of BDNF in EBV-infected B cells resulted in the inhibition of cell proliferation and viability. Downregulation of phosphorylated SMAD2 and STAT3 after BDNF knockdown may play a role in the mechanism. Implantation of latent EBV-infected B cells into rat bladder walls resulted in a higher expression level of CD45 and PGP9.5, suggesting tissue inflammation and nerve hyperplasia. In contrast, implantation of BDNF depleted EBV-infected B cells abrogated these effects. This is the first study to provide insights into the mechanisms underlying the involvement of EBV-infected B cells in HIC pathogenesis. © 2022 The Pathological Society of Great Britain and Ireland.

Valine-279 Deletion-Mutation on Arginine Vasopressin Receptor 2 Causes Obstruction in G-Protein Binding Site: A Clinical Nephrogenic Diabetes Insipidus Case and Its Sub-Molecular Pathogenic Analysis.

Congenital nephrogenic diabetes insipidus (CNDI) is a genetic disorder caused by mutations in arginine vasopressin receptor 2 (AVPR2) or aquaporin 2 genes, rendering collecting duct cells insensitive to the peptide hormone arginine vasopressin stimulation for water reabsorption. This study reports a first identified AVPR2 mutation in Taiwan and demonstrates our effort to understand the pathogenesis caused by applying computational structural analysis tools. The CNDI condition of an 8-month-old male patient was confirmed according to symptoms, family history, and DNA sequence analysis. The patient was identified to have a valine 279 deletion-mutation in the AVPR2 gene. Cellular experiments using mutant protein transfected cells revealed that mutated AVPR2 is expressed successfully in cells and localized on cell surfaces. We further analyzed the pathogenesis of the mutation at sub-molecular levels via long-term molecular dynamics (MD) simulations and structural analysis. The MD simulations showed while the structure of the extracellular ligand-binding domain remains unchanged, the mutation alters the direction of dynamic motion of AVPR2 transmembrane helix 6 toward the center of the G-protein binding site, obstructing the binding of G-protein, thus likely disabling downstream signaling. This study demonstrated that the computational approaches can be powerful tools for obtaining valuable information on the pathogenesis induced by mutations in G-protein-coupled receptors. These methods can also be helpful in providing clues on potential therapeutic strategies for CNDI.

Targeting of interleukin-10 receptor by a potential human interleukin-10 peptide efficiently blocks interleukin-10 pathway-dependent cell proliferation.

OBJECTIVE: Human interleukin-10 (IL-10) is a dimeric and pleiotropic cytokine that plays a crucial role in cellular immunoregulatory responses. As IL-10 binds to its receptors, IL-10Ra and IL-10Rb, it will suppress or induce the downstream cellular immune responses to protect from diseases. MATERIALS AND METHODS: In this study, a potential peptide derived from IL-10 based on molecular docking and structural analysis was designed and validated by a series of cell assays to block IL-10 binding to receptor IL-10Ra for the inhibition of cell growth. RESULTS: The simulation results indicate that the designed peptide IL10NM25 bound to receptor IL-10Ra is dominated by electrostatic interactions, whereas van der Waals (VDW) and hydrophobic interactions are minor. The cell experiments showed that IL10NM25 specifically binds to receptor IL-10Ra on the cell surface of two B-lineage cell lines, B lymphoma derived (BJAB), and lymphoblastoid cell line, whereas the mutant and scramble peptides are not able to suppress the binding of IL-10 to receptor IL-10Ra, consistent with the molecular simulation predictions. CONCLUSION: This study demonstrates that structure-based peptide design can be effective in the development of peptide drug discovery.

B Cell-Specific Transcription Activator PAX5 Recruits p300 To Support EBNA1-Driven Transcription.

The binding of Epstein-Barr Virus (EBV) nuclear antigen 1 (EBNA1) to the latent replication origin (oriP) triggers multiple downstream events to support virus-induced pathogenesis and tumorigenesis. Although EBV is widely recognized as a B-lymphotropic infectious agent, little is known about how tissue-specific factors are involved in the establishment of latency. Here, we showed that EBNA1 binds B cell activator PAX5 to promote EBNA1/oriP-dependent binding and transcription. In addition to showing that short hairpin RNA (shRNA)-mediated PAX5 knockdown substantially abrogated the above EBNA1-dependent functions, two mini-EBV reporter plasmids were used to perform nonlytic nano-luciferase (nLuc) activity and chromatin immunoprecipitation (ChIP) assays to show how EBNA1 cooperates with PAX5 to activate the transcription at the oriP site. The expression plasmids of two PAX5 mutants, V26G (EBNA1 binding mutant) and P80R (which remained EBNA1 associated), were used to assess their capability to restore the defects caused by PAX5 depletion in EBNA1/oriP-mediated binding, transcription, and maintenance of the genome copy number of the mini-EBV episome reporter in BJAB cells stably expressing EBNA1 or that of the EBV genome in EBV-infected BJAB cells. Since p300 is known to be associated with PAX5, we showed that the loss of function of the P80R mutant in support of EBNA1/oriP-mediated transcription under PAX5 depletion conditions was linked to its defective binding to p300. ChIP-quantitative PCR (qPCR) confirmed that P80R indeed failed to recruit p300 to the oriP DNA. Our discovery suggests that EBV has evolved an exquisite strategy to take advantage of tissue-specific factors to enable the establishment of viral latency.IMPORTANCE Although B cells are known to be the primary target for EBV infection, there is limited knowledge regarding the mechanism that determines this preferable tissue tropism. An in-depth understanding of the potential link of tissue-specific factors with the viral genes and their functioning is key to deciphering how EBV induces persistent infection in the distinct types of host cells. In this study, a substantial protein-protein interaction mediated by the B cell-specific activator PAX5 and EBNA1 was identified as the general requirement for the binding of EBNA1 to the latent replication origin and for downstream events. Of importance, the EBNA1-PAX5-p300 network is directly linked to EBNA1-dependent transcription. These findings suggest that targeting the viral gene-associated tissue-specific factors may lead to new therapeutic strategies for EBV-associated malignancies.

GAP31 from an ancient medicinal plant exhibits anti-viral activity through targeting to Epstein-Barr virus nuclear antigen 1.

Since it was discovered as the first human tumor virus in 1964, Epstein-Barr Virus (EBV) is now implicated in several types of malignancies. Accordingly, certain aspects of EBV pathobiology have shown promise in anti-cancer research in developing virus-targeting methods for EBV-associated cancers. The unique role of EBV nuclear antigen 1 (EBNA1) in triggering episome-dependent functions has made it as the only latent gene to be expressed in most EBV+ neoplasms. Dimeric EBNA1 binds to the replication origin (oriP) to display its biological impact on EBV-driven cell transformation and maintenance. Hence, EBNA1/oriP has been made an ideal drug target site for anti-EBV protocol development. GAP31 protein was originally isolated from the seeds of an ancient medicinal plant Gelonium multiflorum. Although GAP31 has been shown to exhibit both anti-viral and anti-tumor activity, current understanding of the mechanistic picture underlying GAP31 functioning is not clear. Herein, we identify the EBNA1 DNA-binding domain as a core for GAP31 binding by performing affinity pulldown assays. Recombinant GAP31 (rGAP31) was shown to impair EBNA1-induced dimerization; consequently, it abrogated both EBNA1/oriP-mediated binding and transcription. Importantly, the therapeutic effects of GAP31 showed its capability to abrogate EBV-driven cell transformation and proliferation, and EBV-dependent tumorigenesis in xenograft animal models. Notably, the EBNA1 binding-mutant rGAP31R166A/R169A simply exhibits defective phenotypes in the above-mentioned studies. Our data suggest rGAP31 is a potential anti-viral drug which can be applied to the development of therapeutic strategies against EBV-related malignancies.

Epstein-Barr Virus as a Potential Etiology of Persistent Bladder Inflammation in Human Interstitial Cystitis/Bladder Pain Syndrome.

PURPOSE: Interstitial cystitis/bladder pain syndrome is characterized by bladder inflammation without bacterial infection. Although viral infection is a potential etiological cause, few studies have been reported. MATERIALS AND METHODS: Bladder specimens were obtained from patients with interstitial cystitis/bladder pain syndrome and from patients with stress urinary incontinence as controls. Bladder specimens were tested for Epstein-Barr encoded RNAs by in situ hybridization and for Epstein-Barr DNA by quantitative real-time polymerase chain reaction, serology and immunohistochemical staining. RESULTS: Enrolled in study were 16 patients with interstitial cystitis/bladder pain syndrome and Hunner lesions, 23 without interstitial cystitis/bladder pain syndrome or Hunner lesions and 10 controls. The positive rate of Epstein-Barr encoded RNA on in situ hybridization in bladder specimens from patients with vs without interstitial cystitis/bladder pain syndrome and Hunner lesions was 50% vs 8.6%. No Epstein-Barr encoded RNA was found in control specimens. On quantitative real-time polymerase chain reaction Epstein-Barr DNA was detected in 68.8% vs 16.7% of bladder specimens in patients with vs without interstitial cystitis/bladder pain syndrome and Hunner lesions. The median viral load was 1,836 copies per ml (range 216 to 75,144). Only 1 control specimen was Epstein-Barr positive on quantitative real-time polymerase chain reaction. All serum samples from patients with interstitial cystitis/bladder pain syndrome showed past Epstein-Barr viral infection. Epstein-Barr infection was present in 87.5% vs 17.4% of bladder specimens from patients with vs without interstitial cystitis/bladder pain syndrome and Hunner lesions for a total of 46.2% with interstitial cystitis/bladder pain syndrome. Immunohistochemical staining of CD3 and CD20 revealed that Epstein-Barr infection was mainly restricted to T lymphocytes in bladders showing interstitial cystitis/bladder pain syndrome. CONCLUSIONS: Bladder Epstein-Barr infection in T cells may be linked to the pathogenesis of persistent inflammation in patients with interstitial cystitis/bladder pain syndrome.

Epstein-Barr Virus Nuclear Antigen Leader Protein Coactivates EP300.

Epstein-Barr virus nuclear antigen (EBNA) leader protein (EBNALP) is one of the first viral genes expressed upon B-cell infection. EBNALP is essential for EBV-mediated B-cell immortalization. EBNALP is thought to function primarily by coactivating EBNA2-mediated transcription. Chromatin immune precipitation followed by deep sequencing (ChIP-seq) studies highlight that EBNALP frequently cooccupies DNA sites with host cell transcription factors (TFs), in particular, EP300, implicating a broader role in transcription regulation. In this study, we investigated the mechanisms of EBNALP transcription coactivation through EP300. EBNALP greatly enhanced EP300 transcription activation when EP300 was tethered to a promoter. EBNALP coimmunoprecipitated endogenous EP300 from lymphoblastoid cell lines (LCLs). EBNALP W repeat serine residues 34, 36, and 63 were required for EP300 association and coactivation. Deletion of the EP300 histone acetyltransferase (HAT) domain greatly reduced EBNALP coactivation and abolished the EBNALP association. An EP300 bromodomain inhibitor also abolished EBNALP coactivation and blocked the EP300 association with EBNALP. EBNALP sites cooccupied by EP300 had significantly higher ChIP-seq signals for sequence-specific TFs, including SPI1, RelA, EBF1, IRF4, BATF, and PAX5. EBNALP- and EP300-cooccurring sites also had much higher H3K4me1 and H3K27ac signals, indicative of activated enhancers. EBNALP-only sites had much higher signals for DNA looping factors, including CTCF and RAD21. EBNALP coactivated reporters under the control of NF-κB or SPI1. EP300 inhibition abolished EBNALP coactivation of these reporters. Clustered regularly interspaced short palindromic repeat interference targeting of EBNALP enhancer sites significantly reduced target gene expression, including that of EP300 itself. These data suggest a previously unrecognized mechanism by which EBNALP coactivates transcription through subverting of EP300 and thus affects the expression of LCL genes regulated by a broad range of host TFs.IMPORTANCE Epstein-Barr virus was the first human DNA tumor virus discovered over 50 years ago. EBV is causally linked to ∼200,000 human malignancies annually. These cancers include endemic Burkitt lymphoma, Hodgkin lymphoma, lymphoma/lymphoproliferative disease in transplant recipients or HIV-infected people, nasopharyngeal carcinoma, and ∼10% of gastric carcinoma cases. EBV-immortalized human B cells faithfully model key aspects of EBV lymphoproliferative diseases and are useful models of EBV oncogenesis. EBNALP is essential for EBV to transform B cells and transcriptionally coactivates EBNA2 by removing repressors from EBNA2-bound DNA sites. Here, we found that EBNALP can also modulate the activity of the key transcription activator EP300, an acetyltransferase that activates a broad range of transcription factors. Our data suggest that EBNALP regulates a much broader range of host genes than was previously appreciated. A small-molecule inhibitor of EP300 abolished EBNALP coactivation of multiple target genes. These findings suggest novel therapeutic approaches to control EBV-associated lymphoproliferative diseases.

Impact of cuticle photoluminescence on the color morphism of a male damselfly Ischnura senegalensis (Rambur, 1842).

In this study the damselfly Ischnura senegalensis (Rambur, 1842) was first found to produce strong photoluminescence (PL) emissions from various colored-body portions, such as the eighth abdominal segment of the tail. The colors of the colored-body portions can be enhanced or modified by the PL emissions for assistance in reducing intrasexual and male harassment, and improving mature mating and conspecific identity. Therefore, the PL emissions that contribute to the color modification and coloration are involved in the cuticle evolution of the damselflies. The micro-PL confocal images verify that the PL emissions can strongly influence the surface colors of the cuticle, and demonstrate why the damselfly Ischnura senegalensis is called a bluetail.

BS69/ZMYND11 C-Terminal Domains Bind and Inhibit EBNA2.

Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2) plays an important role in driving immortalization of EBV-infected B cells through regulating the expression of many viral and cellular genes. We report a structural study of the tumor suppressor BS69/ZMYND11 C-terminal region, comprised of tandem coiled-coil-MYND domains (BS69CC-MYND), in complex with an EBNA2 peptide containing a PXLXP motif. The coiled-coil domain of BS69 self-associates to bring two separate MYND domains in close proximity, thereby enhancing the BS69 MYND-EBNA2 interaction. ITC analysis of BS69CC-MYND with a C-terminal fragment of EBNA2 further suggests that the BS69CC-MYND homodimer synergistically binds to the two EBNA2 PXLXP motifs that are respectively located in the conserved regions CR7 and CR8. Furthermore, we showed that EBNA2 interacts with BS69 and down-regulates its expression at both mRNA and protein levels in EBV-infected B cells. Ectopic BS69CC-MYND is recruited to viral target promoters through interactions with EBNA2, inhibits EBNA2-mediated transcription activation, and impairs proliferation of lymphoblastoid cell lines (LCLs). Substitution of critical residues in the MYND domain impairs the BS69-EBNA2 interaction and abolishes the BS69 inhibition of the EBNA2-mediated transactivation and LCL proliferation. This study identifies the BS69 C-terminal domains as an inhibitor of EBNA2, which may have important implications in development of novel therapeutic strategies against EBV infection.

Ribosome Protein L4 is essential for Epstein-Barr Virus Nuclear Antigen 1 function.

Epstein-Barr Virus (EBV) Nuclear Antigen 1 (EBNA1)-mediated origin of plasmid replication (oriP) DNA episome maintenance is essential for EBV-mediated tumorigenesis. We have now found that EBNA1 binds to Ribosome Protein L4 (RPL4). RPL4 shRNA knockdown decreased EBNA1 activation of an oriP luciferase reporter, EBNA1 DNA binding in lymphoblastoid cell lines, and EBV genome number per lymphoblastoid cell line. EBV infection increased RPL4 expression and redistributed RPL4 to cell nuclei. RPL4 and Nucleolin (NCL) were a scaffold for an EBNA1-induced oriP complex. The RPL4 N terminus cooperated with NCL-K429 to support EBNA1 and oriP-mediated episome binding and maintenance, whereas the NCL C-terminal K380 and K393 induced oriP DNA H3K4me2 modification and promoted EBNA1 activation of oriP-dependent transcription. These observations provide new insights into the mechanisms by which EBV uses NCL and RPL4 to establish persistent B-lymphoblastoid cell infection.

Autophagy promotes radiation-induced senescence but inhibits bystander effects in human breast cancer cells.

Ionizing radiation induces cellular senescence to suppress cancer cell proliferation. However, it also induces deleterious bystander effects in the unirradiated neighboring cells through the release of senescence-associated secretory phenotypes (SASPs) that promote tumor progression. Although autophagy has been reported to promote senescence, its role is still unclear. We previously showed that radiation induces senescence in PTTG1-depleted cancer cells. In this study, we found that autophagy was required for the radiation-induced senescence in PTTG1-depleted breast cancer cells. Inhibition of autophagy caused the cells to switch from radiation-induced senescence to apoptosis. Senescent cancer cells exerted bystander effects by promoting the invasion and migration of unirradiated cells through the release of CSF2 and the subsequently activation of the JAK2-STAT3 and AKT pathways. However, the radiation-induced bystander effects were correlated with the inhibition of endogenous autophagy in bystander cells, which also resulted from the activation of the CSF2-JAK2 pathway. The induction of autophagy by rapamycin reduced the radiation-induced bystander effects. This study reveals, for the first time, the dual role of autophagy in radiation-induced senescence and bystander effects.

Nucleolin is important for Epstein-Barr virus nuclear antigen 1-mediated episome binding, maintenance, and transcription.

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is essential for EBV episome maintenance, replication, and transcription. These effects are mediated by EBNA1 binding to cognate oriP DNA, which comprise 20 imperfect copies of a 30-bp dyad symmetry enhancer and an origin for DNA replication. To identify cell proteins essential for these EBNA1 functions, EBNA1 associated cell proteins were immune precipitated and analyzed by liquid chromatography-tandem mass spectrometry. Nucleolin (NCL) was identified to be EBNA1 associated. EBNA1's N-terminal 100 aa and NCL's RNA-binding domains were critical for EBNA1/NCL interaction. Lentivirus shRNA-mediated NCL depletion substantially reduced EBNA1 recruitment to oriP DNA, EBNA1-dependent transcription of an EBV oriP luciferase reporter, and EBV genome maintenance in lymphoblastoid cell lines. NCL RNA-binding domain K429 was critical for ATP and EBNA1 binding. NCL overexpression increased EBNA1 binding to oriP and transcription, whereas NCL K429A was deficient. Moreover, NCL silencing impaired lymphoblastoid cell line growth. These experiments reveal a surprisingly critical role for NCL K429 in EBNA1 episome maintenance and transcription, which may be a target for therapeutic intervention.

Radiation-induced senescence in securin-deficient cancer cells promotes cell invasion involving the IL-6/STAT3 and PDGF-BB/PDGFR pathways.

Securin overexpression correlates with poor prognosis in various tumours. We have previously shown that securin depletion promotes radiation-induced senescence and enhances radiosensitivity in human cancer cells. However, the underlying molecular mechanisms and the paracrine effects remain unknown. In this study, we showed that radiation induced senescence in securin-deficient human breast cancer cells involving the ATM/Chk2 and p38 pathways. Conditioned medium (CM) from senescent cells promoted the invasion and migration of non-irradiated cancer and endothelial cells. Cytokine assay analysis showed the up-regulation of various senescence-associated secretory phenotypes (SASPs). The IL-6/STAT3 signalling loop and platelet-derived growth factor-BB (PDGF-BB)/PDGF receptor (PDGFR) pathway were important for CM-induced cell migration and invasion. Furthermore, CM promoted angiogenesis in the chicken chorioallantoic membrane though the induction of IL-6/STAT3- and PDGF-BB/PDGFR-dependent endothelial cell invasion. Taken together, our results provide the molecular mechanisms for radiation-induced senescence in securin-deficient human breast cancer cells and for the SASP responses.

Modulation of Epstein-Barr virus nuclear antigen 2-dependent transcription by protein arginine methyltransferase 5.

Epstein-Barr Virus Nuclear Antigen (EBNA) 2 features an Arginine-Glycine repeat (RG) domain at amino acid positions 335-360, which is a known target for protein arginine methyltransferaser 5 (PRMT5). In this study, we performed protein affinity pull-down assays to demonstrate that endogenous PRMT5 derived from lymphoblastoid cells specifically associated with the protein bait GST-E2 RG. Transfection of a plasmid expressing PRMT5 induced a 2.5- to 3-fold increase in EBNA2-dependent transcription of both the LMP1 promoter in AKATA cells, which contain the EBV genome endogenously, and a Cp-Luc reporter plasmid in BJAB cells, which are EBV negative. Furthermore, we showed that there was a 2-fold enrichment of EBNA2 occupancy in target promoters in the presence of exogenous PRMT5. Taken together, we show that PRMT5 triggers the symmetric dimethylation of EBNA2 RG domain to coordinate with EBNA2-mediated transcription. This modulation suggests that PRMT5 may play a role in latent EBV infection.

The nuclear chaperone nucleophosmin escorts an Epstein-Barr Virus nuclear antigen to establish transcriptional cascades for latent infection in human B cells.

Epstein-Barr Virus (EBV) is an oncogenic γ-herpesvirus that capably establishes both latent and lytic modes of infection in host cells and causes malignant diseases in humans. Nuclear antigen 2 (EBNA2)-mediated transcription of both cellular and viral genes is essential for the establishment and maintenance of the EBV latency program in B lymphocytes. Here, we employed a protein affinity pull-down and LC-MS/MS analysis to identify nucleophosmin (NPM1) as one of the cellular proteins bound to EBNA2. Additionally, the specific domains that are responsible for protein-protein interactions were characterized as EBNA2 residues 300 to 360 and the oligomerization domain (OD) of NPM1. As in c-MYC, dramatic NPM1 expression was induced in EBV positively infected B cells after three days of viral infection, and both EBNA2 and EBNALP were implicated in the transactivation of the NPM1 promoter. Depletion of NPM1 with the lentivirus-expressed short-hairpin RNAs (shRNAs) effectively abrogated EBNA2-dependent transcription and transformation outgrowth of lymphoblastoid cells. Notably, the ATP-bound state of NPM1 was required to induce assembly of a protein complex containing EBNA2, RBP-Jκ, and NPM1 by stabilizing the interaction of EBNA2 with RBP-Jκ. In a NPM1-knockdown cell line, we demonstrated that an EBNA2-mediated transcription defect was fully restored by the ectopic expression of NPM1. Our findings highlight the essential role of NPM1 in chaperoning EBNA2 onto the latency-associated membrane protein 1 (LMP1) promoters, which is coordinated with the subsequent activation of transcriptional cascades through RBP-Jκ during EBV infection. These data advance our understanding of EBV pathology and further imply that NPM1 can be exploited as a therapeutic target for EBV-associated diseases.

EGCG debilitates the persistence of EBV latency by reducing the DNA binding potency of nuclear antigen 1.

Because the expression of EBNA1 is prevalent in all EBV-associated tumors, it has become one of the most attractive drug targets for the discovery of anti-EBV compounds. In a cell-based reporter system, EBNA1 consistently upregulated the transcription of an oriP-Luc mini-EBV episome by 6- to 8-fold. The treatment of cells with 50 µM EGCG effectively blocked the binding of EBNA1 to oriP-DNA both in vivo and in vitro, which led to the abrogation of EBNA1-dependent episome maintenance and transcriptional enhancement. Importantly, the anti-EBNA1 effects caused by EGCG ultimately impaired the persistence of EBV latent infection. Our data suggest that the inhibition of EBNA1 activity by EGCG could be a promising starting point for the development of new protocols for anti-EBV therapy.

Dietary flavonoid fisetin targets caspase-3-deficient human breast cancer MCF-7 cells by induction of caspase-7-associated apoptosis and inhibition of autophagy.

The outcome of producing apoptotic defects in cancer cells is the primary obstacle that limits the therapeutic efficacy of anticancer agents, and hence the development of novel agents targeting novel non-canonical cell death pathways has become an imperative mission for clinical research. Fisetin (3,3',4',7-tetrahydroxyflavone) is a naturally occurring flavonoid commonly found in fruits and vegetables. In this study, we investigated the potential anticancer effects of fisetin on breast cancer cells. The result showed fisetin induced higher cytotoxicity in human breast cancer MCF-7 than in MDA-MB-231 cells otherwise it did not exert any detectable cytotoxicity in non-tumorigenic MCF-10A cells. We found fisetin can trigger a novel form of atypical apoptosis in caspase-3-deficient MCF-7 cells, which was characterized by several apoptotic features, including plasma membrane rupture, mitochondrial depolarization, activation of caspase-7, -8 and -9, and PARP cleavage; however, neither DNA fragmentation and phosphotidylserine (PS) externalization was observed. Although p53 was also activated by fisetin, the fisetin-induced apoptosis was not rescued by the p53 inhibitor pifithrin-α. In contrast, the fisetin-induced apoptosis was abrogated by pan-caspase inhibitor z-VAD-fmk. Furthermore, inhibition of autophagy by fisetin was shown as additional route to prompt anticancer activity in MCF-7 cells. These data allow us to propose that fisetin appears as a new potential anticancer agent which can be applied to develop a clinical protocol of human breast cancers.

Epstein-Barr virus exploits intrinsic B-lymphocyte transcription programs to achieve immortal cell growth.

Epstein-Barr virus nuclear antigen 2 (EBNA2) regulation of transcription through the cell transcription factor RBPJ is essential for resting B-lymphocyte (RBL) conversion to immortal lymphoblast cell lines (LCLs). ChIP-seq of EBNA2 and RBPJ sites in LCL DNA found EBNA2 at 5,151 and RBPJ at 10,529 sites. EBNA2 sites were enriched for RBPJ (78%), early B-cell factor (EBF, 39%), RUNX (43%), ETS (39%), NFκB (22%), and PU.1 (22%) motifs. These motif associations were confirmed by LCL RBPJ ChIP-seq finding 72% RBPJ occupancy and Encyclopedia Of DNA Elements LCL ChIP-seq finding EBF, NFκB RELA, and PU.1 at 54%, 31%, and 17% of EBNA2 sites. EBNA2 and RBPJ were predominantly at intergene and intron sites and only 14% at promoter sites. K-means clustering of EBNA2 site transcription factors identified RELA-ETS, EBF-RUNX, EBF, ETS, RBPJ, and repressive RUNX clusters, which ranked from highest to lowest in H3K4me1 signals and nucleosome depletion, indicative of active chromatin. Surprisingly, although quantitatively less, the same genome sites in RBLs exhibited similar high-level H3K4me1 signals and nucleosome depletion. The EBV genome also had an LMP1 promoter EBF site, which proved critical for EBNA2 activation. LCL HiC data mapped intergenic EBNA2 sites to EBNA2 up-regulated genes. FISH and chromatin conformation capture linked EBNA2/RBPJ enhancers 428 kb 5' of MYC to MYC. These data indicate that EBNA2 evolved to target RBL H3K4me1 modified, nucleosome-depleted, nonpromoter sites to drive B-lymphocyte proliferation in primary human infection. The primed RBL program likely supports antigen-induced proliferation.