Shared and distinct interactions of type 1 and type 2 Epstein-Barr Nuclear Antigen 2 with the human genome

BACKGROUND

There are two major genetic types of Epstein-Barr Virus (EBV): type 1 (EBV-1) and type 2 (EBV-2). EBV functions by manipulating gene expression in host B cells, using virus-encoded gene regulatory proteins including Epstein-Barr Nuclear Antigen 2 (EBNA2). While type 1 EBNA2 is known to interact with human transcription factors (hTFs) such as RBPJ, EBF1, and SPI1 (PU.1), type 2 EBNA2 shares only ~ 50% amino acid identity with type 1 and thus may have distinct binding partners, human genome binding locations, and functions.

RESULTS

In this study, we examined genome-wide EBNA2 binding in EBV-1 and EBV-2 transformed human B cells to identify shared and unique EBNA2 interactions with the human genome, revealing thousands of type-specific EBNA2 ChIP-seq peaks. Computational predictions based on hTF motifs and subsequent ChIP-seq experiments revealed that both type 1 and 2 EBNA2 co-occupy the genome with SPI1 and AP-1 (BATF and JUNB) hTFs. However, type 1 EBNA2 showed preferential co-occupancy with EBF1, and type 2 EBNA2 preferred RBPJ. These differences in hTF co-occupancy revealed possible mechanisms underlying type-specific gene expression of known EBNA2 human target genes: MYC (shared), CXCR7 (type 1 specific), and CD21 (type 2 specific). Both type 1 and 2 EBNA2 binding events were enriched at systemic lupus erythematosus (SLE) and multiple sclerosis (MS) risk loci, while primary biliary cholangitis (PBC) risk loci were specifically enriched for type 2 peaks.

CONCLUSIONS

This study reveals extensive type-specific EBNA2 interactions with the human genome, possible differences in EBNA2 interaction partners, and a possible new role for type 2 EBNA2 in autoimmune disorders. Our results highlight the importance of considering EBV type in the control of human gene expression and disease-related investigations.

The lived experience of food insecurity among adults with obesity: a quantitative and qualitative systematic review

BACKGROUND

Food insecurity and obesity are increasing both globally and in the UK. In thisreview we systematically assess the lived experiences of people with obesity who are food insecure and often turn to foodbanks.

METHODS

We systematically searched electronic databases from January 2007 until October 2022. Data from eligible studies were extracted and the studies assessed for quality. Thematicanalysis and narrative synthesis approach was used to analyse the extracted data.

RESULTS

Six themes were identified among 25 included studies, including: the financial cost of food; psychological aspects related to food insecurity; geographical access and the foodenvironment; food practices in the home; experience of food assistance; and parental-childrelationships. The cost of healthy food and psychological factors were identified as keydriving factors of the relationship between food insecurity and obesity. Psychological factorssuch as depression, low self-esteem and stress played an important part in the livedexperience of people with obesity and food insecurity.

CONCLUSION

The food environment provides context in which food decisions are made,therefore, systems change is necessary to ensure families can afford the food that enables ahealthy diet. For clinicians, identification, and attention to the impact of food insecurity onpeople with obesity are important.

Epigenetic and transcriptional dysregulation in CD4+ T cells in patients with atopic dermatitis

Atopic dermatitis (AD) is one of the most common skin disorders among children. Disease etiology involves genetic and environmental factors, with 29 independent AD risk loci enriched for risk allele-dependent gene expression in the skin and CD4+ T cell compartments. We investigated the potential epigenetic mechanisms responsible for the genetic susceptibility of CD4+ T cells. To understand the differences in gene regulatory activity in peripheral blood T cells in AD, we measured chromatin accessibility (an assay based on transposase-accessible chromatin sequencing, ATAC-seq), nuclear factor kappa B subunit 1 (NFKB1) binding (chromatin immunoprecipitation with sequencing, ChIP-seq), and gene expression levels (RNA-seq) in stimulated CD4+ T cells from subjects with active moderate-to-severe AD, as well as in age-matched non-allergic controls. Open chromatin regions in stimulated CD4+ T cells were highly enriched for AD genetic risk variants, with almost half of the AD risk loci overlapping AD-dependent ATAC-seq peaks. AD-specific open chromatin regions were strongly enriched for NF-κB DNA-binding motifs. ChIP-seq identified hundreds of NFKB1-occupied genomic loci that were AD- or control-specific. As expected, the AD-specific ChIP-seq peaks were strongly enriched for NF-κB DNA-binding motifs. Surprisingly, control-specific NFKB1 ChIP-seq peaks were not enriched for NFKB1 motifs, but instead contained motifs for other classes of human transcription factors, suggesting a mechanism involving altered indirect NFKB1 binding. Using DNA sequencing data, we identified 63 instances of altered genotype-dependent chromatin accessibility at 36 AD risk variant loci (30% of AD risk loci) that might lead to genotype-dependent gene expression. Based on these findings, we propose that CD4+ T cells respond to stimulation in an AD-specific manner, resulting in disease- and genotype-dependent chromatin accessibility alterations involving NFKB1 binding.

An amino acid change in IRF7 increases SLE risk through transcriptional regulation of type I interferons

Systemic Lupus Erythematosus (SLE) is an incurable, debilitating autoimmune disease characterized by widespread inflammation and rampant production of autoantibodies. The most prominent and highly replicated set of genes up-regulated in the immune cells of patients with SLE are the type I interferons (IFN-I) and IFN-responsive genes. IFN-I are predominantly made by plasmacytoid dendritic cells (pDCs), and their expression is directly regulated by the transcription factor interferon regulatory factor 7 (IRF7). While IRF7 is an established SLE risk locus, the variants responsible for disease pathology remain unknown. We hypothesize that an amino-acid changing SLE risk variant in IRF7 (rs1131665) alters expression of disease-relevant IFN-I in clinically-relevant cells to increase SLE risk. The functional genomic consequences of the SLE-associated variant were assessed in human cell lines and in genome-edited mice with an introduced SLE-risk variant at Irf7. Our data demonstrate greater than 2-fold genotype-dependence in IFN-stimulated response element-driven luciferase activity and inflammatory cytokine secretion detected in supernatant after toll-like receptor-7 stimulation. Gene expression differences in cells with IRF7/Irf7 risk variants are consistent with those dysregulated in SLE patients. In the present study, we demonstrate the functional consequences of an amino acid substitution in a critical type I interferon regulator. Understanding these mechanisms will enhance development of more effective clinical practices for autoimmune patients expressing the risk variant for IRF7.