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PubMed2025

EBV Latency Programs: Molecular and Epigenetic Regulation and Its Role in Disease Pathogenesis.

Epstein-Barr virus (EBV) asymptomatically infects over 95% of the global population, and poses a great threat to human health. This review summarizes the complex mechanisms underlying EBV latency programs and their roles in both viral persistence and disease development. We comprehensively analyze the four distinct latency programs (0, I, II, and III) and their associated gene expression patterns, with particular emphasis on the key viral proteins, the Epstein-Barr virus nuclear antigen EBNA1, EBNA2, EBNA3A/B/C, LMP1, and LMP2A/B. The review explores how these latency programs contribute to various EBV-associated malignancies and autoimmune conditions, including Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, and multiple sclerosis. We detail the multilayered regulation of EBV latency, encompassing epigenetic modifications, chromatin organization, and long-range genomic interactions. Recent advances in understanding the molecular mechanisms of EBV latency maintenance and the virus's interaction with host cellular machinery provide new insights into potential therapeutic approaches for EBV-associated diseases.

Humans↗
PubMed2025

Viral Enhancers Orchestrate Kaposi's Sarcoma-Associated Herpesvirus Transcription.

Kaposi's sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi's sarcoma and other lymphoproliferative disorders, presents a delicate balance between host cell manipulation, and orchestrating its transcriptional repertoire. Like all herpes viruses, the virus can reside in latency, expressing only a handful of proteins or launch a lytic program that expresses over 80 proteins responsible for the generation and release of new virions. Enhancers, as their name suggests, can enhance the transcription rate from a promoter depending on the cellular environment and tissue. While the promoters in KSHV have been extensively studied, the enhancers were only recently identified. Here we will describe our current view on KSHV enhancers.

Herpesvirus 8, Human↗
PubMed2025

Differentiation latency and dormancy signatures define fetal liver hematopoietic stem cells at single-cell resolution.

Decoding the mechanisms governing the self-renewal of hematopoietic stem cells (HSCs) during their expansion in the fetal liver (FL) could unlock novel therapeutic strategies to expand transplantable HSCs, a long-standing challenge. To explore intrinsic and extrinsic regulation of FL-HSC self-renewal at single-cell resolution, we engineered a culture platform replicating the FL endothelial niche that supports the amplification of serially engraftable HSCs. Leveraging this platform together with single-cell index flow cytometry, live imaging, transplantation assays, and single-cell RNA sequencing, we demonstrate that differentiation latency, cell-division symmetry, and transcriptional signatures of biosynthetic dormancy are distinguishing properties of rare FL-HSCs capable of serial multilineage hematopoietic reconstitution. Our findings support a paradigm in which intrinsic programs and niche-derived signals together facilitate the symmetric self-renewal of FL-HSCs while delaying their active participation in hematopoiesis. Our study also provides a resource for future investigations into intrinsic and extrinsic signaling pathways governing FL-HSC self-renewal.

Hematopoietic Stem Cells↗
PubMed2024

The HIV-1 Transcriptional Program: From Initiation to Elongation Control.

A large body of work in the last four decades has revealed the key pillars of HIV-1 transcription control at the initiation and elongation steps. Here, I provide a recount of this collective knowledge starting with the genomic elements (DNA and nascent TAR RNA stem-loop) and transcription factors (cellular and the viral transactivator Tat), and later transitioning to the assembly and regulation of transcription initiation and elongation complexes, and the role of chromatin structure. Compelling evidence support a core HIV-1 transcriptional program regulated by the sequential and concerted action of cellular transcription factors and Tat to promote initiation and sustain elongation, highlighting the efficiency of a small virus to take over its host to produce the high levels of transcription required for viral replication. I summarize new advances including the use of CRISPR-Cas9, genetic tools for acute factor depletion, and imaging to study transcriptional dynamics, bursting and the progression through the multiple phases of the transcriptional cycle. Finally, I describe current challenges to future major advances and discuss areas that deserve more attention to both bolster our basic knowledge of the core HIV-1 transcriptional program and open up new therapeutic opportunities.

HIV-1↗
PubMed2025

Tracking HIV persistence across T cell lineages during early ART-treated HIV-1-infection using a reservoir-marking humanized mouse model.

Human immunodeficiency virus (HIV) infection depletes CD4 T-cells, and long-term persistence of latent virus prevents full clearance of HIV even in the presence of effective antiretroviral therapy (ART), Here we present the HIV-1-induced lineage tracing (HILT) system, a model that irreversibly marks infected cells within a humanized mouse model, which detects rare latently infected cells. Immunodeficient mice transplanted with genetically modified hematopoietic stem cells develop a human immune system, in which CD4 T-cells contain a genetic switch that permanently labels cells infected by HIV-1 expressing cre-recombinase. Through single-cell RNA sequencing of HILT-marked cells during acute infection and post-ART treatment, we identify distinct CD4+ T-cell transcriptional lineages enriched in either active or latent infections. Comparative gene expression analysis highlights common pathways modulated in both states, including EIF2, Sirtuin, and protein ubiquitination. Critical regulators of these pathways, including JUN, BCL2, and MDM2, change to opposite directions in the two states, highlighting gene expression programs that may support HIV persistence across T-cell lineages and states.

Animals↗
PubMed2026

Early-onset colorectal cancer burden attributable to early-life obesity from 2000 to 2020 with projections to 2040.

PURPOSE: Early-onset colorectal cancer (age <50 years) incidence has increased globally since the 1990s for unknown reasons. Early-life exposure to established risk factors like adiposity is suspected to play a role, but the contribution to the rising disease burden remains unknown. This study quantified the potential impact of rising early-life obesity on early-onset colorectal cancer in Australia. METHODS: Population attributable fractions for early-onset colorectal cancer were derived from meta-analytic relative risks and obesity prevalence estimates in adolescents (10-19-year-olds), using body mass index data for 1990-2022 from the Noncommunicable Diseases Risk Factor Collaboration. Under age-specific carcinogenesis latency assumptions, we linked adolescent obesity prevalence estimates to colorectal cancer incidence across age groups (20-29, 30-39, and 40-49 years) using observed cancer incidence data from Australian cancer registries covering 2000-2019 and age-period-cohort modelling to generate scenario-based estimates of incidence and obesity-attributable cases through 2040. Trends in obesity-attributable colorectal cancer incidence were quantified using joinpoint regression. RESULTS: The proportion of early-onset colorectal cancers attributable to adolescent obesity across 1990-2022 rose from 2% to 6% in men and 1-3% in women (average annual change: 3-4%). Although absolute attributable incidence rates were low, they increased 2-20% per year, varying by period, age-dependent lag, and sex. Under the projection assumptions applied, scenario estimates suggest that adolescent obesity could account for an estimated 1465 early-onset cases by 2040. CONCLUSION: Early-life obesity is estimated to account for a growing yet minor fraction of early-onset colorectal cancers in Australia and is therefore unlikely to be a major driver of the rising disease incidence. These findings suggest that childhood obesity prevention programs may have only a small public health impact on early-onset colorectal cancer prevention. Therefore, it is imperative that other causal risk factors - especially early-life exposures - are identified to inform prevention strategies that stem the rising disease burden.

Obesity↗
PubMed2025

Heat shock factor 2 regulates oncogenic gamma-herpesvirus gene expression by remodeling the chromatin at the ORF50 and BZLF1 promoter.

The Human gamma-herpesviruses Kaposi's sarcoma herpesvirus (KSHV) and Epstein-Barr virus (EBV) are causally associated to a wide range of cancers. While the default infection program for these viruses is latent, sporadic lytic reactivation supports virus dissemination and oncogenesis. Despite its relevance, the repertoire of host factors governing the transition from latent to lytic phase is not yet complete, leaving much of this complex process unresolved. Here we show that heat shock factor 2 (HSF2), a transcription factor involved in regulation of stress responses and specific cell differentiation processes, promotes gamma-herpesvirus lytic gene expression. In lymphatic endothelial cells infected with KSHV and in gastric cancer cells positive for EBV, ectopic HSF2 enhances the expression of lytic genes; While knocking down HSF2 significantly decreases their expression. HSF2 overexpression is accompanied by decreased levels of repressive histone marks at the promoters of the lytic regulators KSHV ORF50 and EBV BZLF1, both characterized by poised chromatin features. Our results demonstrate that endogenous HSF2 binds to the promoters of KSHV ORF50 and EBV BZLF1 genes and shifts the bivalent chromatin state towards a more transcriptionally permissive state. We detected HSF2 binding to the ORF50 promoter in latent cells, in contrast, in lytic cells, HSF2 occupancy at the ORF50 promoter is lost in conjunction with its proteasomal degradation. These findings identify HSF2 as a regulator of gamma-herpesvirus lytic gene expression in latency and offer new insights on the function of this transcription factors at poised gene promoters, improving our understanding of its role in differentiation and development.

Humans↗
PubMed2026

The brain as an HIV reservoir: Recent findings using autopsy tissues from people with HIV.

HIV persistence within anatomical reservoirs remains the primary barrier to achieving an HIV cure. While antiretroviral therapy effectively suppresses plasma viremia, it does not eliminate integrated proviral genomes that persist in long-lived cellular compartments. The central nervous system (CNS) is a clinically important HIV reservoir, characterized by immune privilege and the persistence of tissue-resident infection despite effective antiretroviral therapy (ART). Evidence from postmortem studies reveals that HIV DNA, RNA, and even intact replication-competent proviruses remain detectable in brain tissue from virally suppressed people with HIV. Evidence derived primarily from in situ approaches and viable-cell studies supports myeloid-lineage reservoirs, particularly microglia and CNS-associated macrophages, as key cellular sources of persistence, while the extent and biological relevance of astrocyte infection remains debated. These reservoirs exhibit transcriptional activity and are associated with chronic neuroinflammation, which may contribute to HIV-associated neurocognitive disorders, despite systemic viral suppression. Here, we synthesize recent findings from autopsy brain studies, including work enabled by major biorepositories, such as the National NeuroHIV Tissue Consortium and rapid-autopsy programs, including the Last Gift, both of which are essential for studying HIV reservoirs in the CNS. We summarize methodologies for detecting and characterizing HIV in brain tissue, highlight heterogeneous patterns of regional distribution and compartmentalization, and review emerging links between CNS persistence and neuroinflammation. We conclude with priorities for harmonized tissue processing, multi-modal single-cell and spatial profiling, and coordinated cross-cohort analyses to clarify the contribution of CNS reservoirs to neuroHIV pathogenesis and systemic rebound.

Humans↗
PubMed2026

Sugar rationing during the first 1000 days and early onset cancer: a natural experiment.

BACKGROUND: The "first 1000 days" of life is a critical window for metabolic programming, while the long-term oncological consequences of nutritional exposures during this period remain understudied. OBJECTIVES: We aimed to evaluate whether restricted sugar intake in utero and during early childhood reduces risk of early onset cancer diagnosis and mortality in adulthood, utilizing a natural experiment. METHODS: We analyzed 63,819 United Kingdom Biobank participants born between October 1951 and March 1956, spanning the end of United Kingdom sugar rationing (September 1953). Leveraging a quasi-experimental birth cohort design, we compared participants exposed to sugar rationing in utero and during infancy with those unexposed. Early onset cancer incidence (&#x2264;50 y) and mortality were ascertained via integrated national Cancer Registry and hospital inpatient records. Multivariable Cox proportional hazards models (including Gompertz distribution) were used to estimate hazard ratios (HRs), with exploratory site-specific analyses. RESULTS: Among 63,819 participants (56.3% female), 40,397 were exposed to rationing and 23,422 were unexposed. Early life sugar restriction significantly reduced early onset cancer risk (HR: 0.66; 95% confidence interval: 0.53, 0.81; P < 0.001). A dose-response relationship was observed, with peak protection in individuals exposed for &#x2264;24 mo postnatally. This protection was observed systemically across solid tumors, independent of specific cancer sites. Specificity was corroborated by null associations with negative controls (herpes zoster and cataract). No significant difference was found for cancer-specific mortality. CONCLUSIONS: Restricting sugar intake during the first 1000 days is associated with a reduced risk of early onset cancer, extending the disease-free lifespan. The divergence between reduced incidence and unchanged mortality suggests early life metabolic environments primarily influence tumor latency rather than biological aggressiveness. These findings highlight the potential long-term public health implications of early life dietary guidelines against the rising burden of early onset cancer.

Humans↗