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

Epstein-Barr virus suppresses N6-methyladenosine modification of TLR9 to promote immune evasion

Epstein-Barr virus (EBV) is a human tumor virus associated with a variety of malignancies, including nasopharyngeal carcinoma, gastric cancers, and B-cell lymphomas. N6-methyladenosine (m6A) modifications modulate a wide range of cellular processes and participate in the regulation of virus-host cell interactions. Here, we discovered that EBV infection downregulates toll-like receptor 9 (TLR9) m6A modification levels and thus inhibits TLR9 expression. TLR9 has multiple m6A modification sites. Knockdown of METTL3, an m6A "writer", decreases TLR9 protein expression by inhibiting its mRNA stability. Mechanistically, Epstein-Barr nuclear antigen 1 increases METTL3 protein degradation via K48-linked ubiquitin-proteasome pathway. Additionally, YTHDF1 was identified as an m6A "reader" of TLR9, enhancing TLR9 expression by promoting mRNA translation in an m6A -dependent manner, which suggests that EBV inhibits TLR9 translation by "hijacking" host m6A modification mechanism. Using the METTL3 inhibitor STM2457 inhibits TLR9-induced B cell proliferation and immunoglobulin secretion, and opposes TLR9-induced immune responses to assist tumor cell immune escape. In clinical lymphoma samples, the expression of METTL3, YTHDF1, and TLR9 was highly correlated with immune cells infiltration. This study reveals a novel mechanism that EBV represses the important innate immunity molecule TLR9 through modulating the host m6A modification system.

Paired Box 5 (PAX5) Gene Has Diagnostic and Prognostic Potential in Nasopharyngeal Carcinoma

Purpose

Paired Box 5 (PAX5) is a transcription factor that is widely associated with carcinogenesis. PAX5 can maintain Epstein-Barr virus (EBV) latency in B cells, while a close association exists between EBV infection and nasopharyngeal carcinoma (NPC). However, there are very few reports on the correlation between PAX5 and NPC development. The aim of this study was to investigate the role of PAX5 in NPC.

Patients and Methods

The clinical value and prognostic significance of PAX5 in NPC and the association with PAX5 expression and immune cell infiltration were analyzed by multiple GEO datasets. In vivo and in vitro experiments including real-time PCR, Western blot, CCK-8 assay, and methylation sequencing were used to validate the results of bioinformatics analysis.

Results

The expression of PAX5 was significantly reduced in NPC tissues, with the low expression being correlated with advanced clinical stage, low tumor mutation burden and immune activation, high relative expression of EBV, poor survival for NPC patients. PAX5 exhibited excellent diagnostic performance and had potential as a predictive factor for response to the immune checkpoint inhibitors therapy. Enrichment analysis suggested that the low expression of PAX5 was associated with the dysregulation of Hippo and Wnt signaling pathways. The promoter of PAX5 gene was hypermethylated in NPC tissues. Furthermore, the in vitro and in vivo experiments revealed that NPC tissue and cell lines had low mRNA expression levels of PAX5, the PAX5 promoter was hypermethylated in NPC cell lines, and PAX5 overexpression inhibited NPC cell proliferation and tumor growth in nude mice.

Conclusion

PAX5 may be a tumor suppressor and serve as a novel potential diagnostic and prognostic marker for NPC.

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.

Stress-Induced Epstein-Barr Virus Reactivation

Epstein-Barr virus (EBV) is typically found in a latent, asymptomatic state in immunocompetent individuals. Perturbations of the host immune system can stimulate viral reactivation. Furthermore, there are a myriad of EBV-associated illnesses including various cancers, post-transplant lymphoproliferative disease, and autoimmune conditions. A thorough understanding of this virus, and the interplay between stress and the immune system, is essential to establish effective treatment. This review will provide a summary of the interaction between both psychological and cellular stressors resulting in EBV reactivation. It will examine mechanisms by which EBV establishes and maintains latency and will conclude with a brief overview of treatments targeting EBV.

PAX5 activates telomerase activity and proliferation in keloid fibroblasts by transcriptional regulation of SND1, thus promoting keloid growth in burn-injured skin

OBJECTIVE

Staphylococcal nuclease domain-containing 1 (SND1) that functioned as an oncogene in a variety of tumors was upregulated in burn-injured skin tissues, and this study aims to investigate the effect of SND1 on keloid and elucidate the underlying mechanism.

METHODS

Keloid fibroblasts (KFs) and normal skin fibroblasts (NFs) were isolated from the keloid tissues and adjacent normal skin tissues of keloid patients. The SND1 expression was assessed in keloid tissues and KFs with Western blot assay. Gain- and loss-of-function experiments were performed to investigate the role of SND1 in proliferation, colony formation, telomerase activity, expression of fibrogenic genes and production of pro-inflammatory factors in KFs. Chromatin immunoprecipitation (CHIP) and Dual-luciferase reporter gene assays were used to verify the interaction of Paired-box gene 5 (PAX5) on SND1 promoter. Then, a series of rescue experiments were performed to verify the effects of SND1 overexpression on PAX5 knockdown-mediated KF functions. Finally, the role of SND1 in keloid formation in vivo was validated in mice with keloid implantation.

RESULTS

SND1 was upregulated in keloid tissues and KFs. SND1 positively regulated proliferation, colony formation, telomerase activity, production of pro-inflammatory factors and expression of fibrogenic genes. PAX5 directly bound to the SND1 promoter to transcriptionally regulate SND1 expression and positively regulated SND1-mediated KF functions via the ERK/JNK pathway. In vivo assay further demonstrated that SND1 displayed a positive effect on keloid formation.

CONCLUSION

SND1 transcriptionally regulated by PAX5 promotes keloid formation through activating telomerase activity via the ERK/JNK signaling pathways, which provides a promising therapeutic target for clinical treatment of burned skin keloid.

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.