During aging, hepatic structural, metabolic, and regulatory impairments collectively contribute to the decline of hepatic and systemic function. As a core hepatic physiological process, ammonia metabolism is essential for maintaining systemic nitrogen homeostasis. However, how ammonia metabolism is altered during aging, and whether these changes contribute to hepatic and systemic decline, remain insufficiently understood. In this review, current evidence linking hepatic ammonia metabolism to liver aging is summarized. The major pathways of hepatic ammonia disposal, including the urea cycle and glutamine synthesis, are first outlined. Age-related changes in these pathways are then discussed, with emphasis on mitochondrial dysfunction, altered post-translational regulation, transcriptional and epigenetic remodeling, and disruption of metabolic zonation. Emerging evidence that ammonia functions not only as a nitrogen waste product but also as a bioactive stress signal is also reviewed. In this context, ammonia has been implicated in mitochondrial injury, senescence-associated signaling, proteostasis defects, and inflammatory and fibrogenic remodeling. The systemic consequences of ammonia dysregulation are further considered, particularly along the liver-brain, liver-muscle, and liver-gut axes. Finally, current and emerging therapeutic strategies are evaluated, including ammonia-lowering agents, senotherapeutics, and microbiota-directed approaches. Collectively, this review identify ammonia metabolism as an underappreciated but potentially axis for understanding liver aging, thereby providing a framework for future mechanistic and translational studies.
Breast cancer (BC) is the second leading cause of cancer-related deaths worldwide and has a high recurrence rate. This study aimed to evaluate the expression levels of three biomarkers: DNA methyltransferase 1 (DNMT1), histone deacetylase 1 (HDAC1), and metallothionein 1E (MT1E) in BC patients. Peripheral blood and tissue samples from 95 female BC patients and 50 age-matched (±5 years) healthy female controls were analyzed using an enzyme-linked immunosorbent assay (ELISA). Diagnostic potential was assessed through receiver operating characteristic (ROC) curve analysis. In silico analyses identified differentially expressed genes (DEGs), Gene Ontology (GO) terms, pathway enrichment, correlation analysis, miRNA-mRNA interactions, and drug-gene networks. Both experimental and computational results revealed significantly higher levels of DNMT1 and HDAC1 but lower levels of MT1E in BC patients compared to controls (p-value < 0.0001). Furthermore, tumor expression of these genes correlated with molecular subtypes, showing distinct expression patterns in triple-negative BC (TNBC). Advanced-stage tumors also exhibited increased HDAC1 and DNMT1 expression. GO enrichment analysis indicated that these DEGs are involved in cell division, differentiation, and nuclear functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis linked DNMT1 to the p53 pathway, HDAC1 to mismatch repair, and MT1E to cytokine receptor interactions. The strongest gene correlations were DNMT1-ILF3, HDAC1-RBBP4, and MT1E-MT2A. Additionally, miRNA-mRNA interaction analysis revealed that DNMT1, HDAC1, and MT1E are targeted by multiple miRNAs, with the top interacting miRNAs being hsa-miR-103a-3p for DNMT1, hsa-miR-34a-5p for HDAC1, and hsa-miR-126-3p for MT1E. DNMT1 showed the highest number of miRNA interactions among the three genes. Moreover, 98 drugs were found to interact with these three genes. ROC analysis demonstrated promising diagnostic performance, with areas under the curve (AUC) of 0.916 for DNMT1, 0.792 for HDAC1, and 0.683 for MT1E (95% confidence interval [CI]). These findings suggest that DNMT1, HDAC1, and MT1E show potential as complementary biomarkers in BC diagnosis. However, further validation in larger cohorts and functional studies are warranted.
Mammalian fertility is dependent upon meiosis, a specialized cell division by which diploid progenitors undergo one round of DNA replication followed by two rounds of chromosomal segregation to produce haploid gametes. The germ line in the testis and ovary undergoes several rounds of mitotic divisions before ultimately transitioning to the meiotic cell cycle. This transition is achieved by replacing the mitotic cell cycle program with the meiotic one. Here, we discuss the molecular players that regulate the transition from mitosis to meiosis. In spermatogenesis, MEIOC, YTHDC2, and RBM46 form an RNA-binding complex that post-transcriptionally represses the mitotic cell cycle program, while in oogenesis, MEIOC inhibits mitotic cycling prior to meiotic initiation. STRA8 and MEIOSIN act as a transcription factor complex to drive meiotic initiation by upregulating genes involved in cell cycle progression and the unique chromosomal events of meiosis in oogenesis and spermatogenesis. These complexes are activated by upstream molecular players, including transcription factors, epigenetic regulators of chromatin structure, and extrinsic signaling factors, that form an intricate and reinforced molecular network to precisely regulate the transition from the mitotic to meiotic cell cycle. Here, we integrate current knowledge of the regulation of meiotic initiation in mammals and highlight key gaps in this regulatory program that remain to be explored.
For much of its history, forensic toxicology was built on a core analytical question: what poison or drug is present, and at what concentration? That question still matters, but modern casework increasingly shows that it is no longer sufficient on its own. The field grew from the nineteenth-century chemical toxicology of Mathieu Orfila and the arsenic-detecting Marsh test into a discipline central to medicolegal death investigation, overdose certification, and exposure reconstruction. Yet contemporary practice must now contend with novel psychoactive substances, highly potent synthetic opioids, complex polysubstance deaths, delayed reporting, postmortem redistribution, matrix degradation, and incomplete toxicological context. These pressures are pushing forensic toxicology beyond simple compound detection toward mechanism-aware, data-rich interpretation. This review develops the idea of precision forensic toxicology as a proposed, forward-looking conceptual framework for that transition rather than a description of established or routinely implemented forensic practice. In this model, classical analytical chemistry remains essential, but it is connected to toxicogenomics, transcriptomics, epigenomics, proteomics, metabolomics, exposomics, microbiomics, and spatial multi-omics, then integrated through systems toxicology and artificial intelligence. Recent literature shows that toxicogenomics can reveal early molecular perturbations before overt phenotype, that postmortem metabolomics can assist cause-of-death screening, that RNA- and miRNA-based markers may improve postmortem interval estimation, and that machine learning can strengthen high-resolution mass-spectrometry workflows and multi-omics interpretation. At the same time, routine implementation remains constrained by standardization, validation, explainability, privacy governance, and regulatory uncertainty. None of these components is yet part of routine forensic casework; each remains at a research or early-validation stage, and their translation into daily practice will require dedicated feasibility, validation, and regulatory work, which this review discusses explicitly. Taken together, the evidence suggests that the future of poisoning investigation will depend less on any single assay and more on interoperable workflows that connect toxicant detection with biological response, individual susceptibility, and transparent decision support, and that these workflows are intended to complement, not replace, classical toxicological and medicolegal interpretation.
Cytoskeleton is an important component of cell structure and function. In the cardiovascular system, it is involved in the remodeling process of a variety of cardiovascular diseases, including cardiac fibrosis, valvular disease, atrial fibrillation, thoracic aortic aneurysm and vascular stiffness related changes. Recent studies have shown that there is a significant synergy between cytoskeletal regulation and epigenetic processes. Notably, epigenetic alterations have been identified as one of the core features of ageing, a major risk factor for cardiovascular disease. Together, these factors regulate the fate determination, function maintenance and pathological transformation of cardiovascular cells. This review focuses on how age-related epigenetic changes, such as DNA methylation, histone modifications, and chromatin remodeling, directly affect cytoskeletal dynamics and nuclear mechanics, and ultimately lead to cardiovascular remodeling. This review systematically summarizes the key molecular pathways that drive pathological remodeling of cardiomyocytes during contraction, phenotypic switching of vascular smooth muscle cells, and activation of fibroblasts. In addition, we discuss potential therapeutic targets, biomarkers, and intervention strategies in this rapidly evolving field to address current challenges and identify future directions for research in order to lay the theoretical foundation for precision medicine in cardiovascular disease.
Measures of biological aging based on DNA methylation (epigenetic clocks) are commonly used in research across the biological, health, and social sciences. Many decisions are made during the quality control (QC) of the data on which such clocks are based, generating removed beta values that must be accommodated in construction of the clocks. We apply a range of detection p-value and bead count thresholds during QC of a DNA methylation dataset and characterize the removed beta values. We then test different methods of imputing removed beta values and their impact on epigenetic clocks. We find that both detection p-value and bead count thresholds remove beta values that differ significantly in their distribution from the values retained post-QC. Epigenetic clocks calculated from datasets using various imputation methods (mean, median, KNN, and methyLImp) do not appear to have consistent patterns of bias. The only exception is imputation of 0 for removed beta values (akin to leaving out those CpGs on a per-sample basis when calculating clocks), which shows stronger proportional bias of clock values for all clocks. We recommend imputing removed beta values rather than leaving those CpGs out of clock calculations on a per-sample basis.
UHRF1 is a key epigenetic regulator implicated in the tumorigenesis of various cancers through DNA methylation; however, its specific mechanisms in the progression of lung adenocarcinoma (LUAD) remain poorly understood. This study aims to elucidate the regulatory role of UHRF1 in LUAD, focusing on its impact on cuproptosis. UHRF1 expression and its correlation with patient prognosis were analyzed using the TCGA-LUAD dataset. Expression levels of UHRF1 and FDX1 in LUAD cell lines were verified via qPCR and Western blot. Gene Set Enrichment Analysis (GSEA) was employed to explore UHRF1-associated pathways. The impact of UHRF1 on cuproptosis was assessed using CCK-8 assays, metabolite detection, and apoptosis analysis. Mechanistically, Chromatin Immunoprecipitation (ChIP) and Methylation-Specific PCR (MSP) were performed to investigate the binding and methylation status of the FDX1 promoter. Finally, the oncogenic role of UHRF1 was validated in vivo using a xenograft mouse model. Clinical analysis revealed that elevated UHRF1 expression in LUAD tissues is significantly associated with poor prognosis. At the cellular level, UHRF1 overexpression downregulated FDX1 expression and inhibited DLAT oligomerization. Functional enrichment analysis indicated that UHRF1 is involved in metabolic reprogramming; specifically, its overexpression enhanced glycolysis while suppressing cuproptosis. Mechanistic studies demonstrated that UHRF1 binds directly to the FDX1 promoter, inducing hypermethylation and subsequent transcriptional silencing. Rescue experiments confirmed that restoring FDX1 expression reverses the cuproptosis-suppressive effects of UHRF1. In vivo, UHRF1 knockdown retarded tumor growth and promoted cell death, whereas concurrent FDX1 knockdown attenuated these tumor-suppressive effects. UHRF1 negatively regulates FDX1 expression through DNA methylation, thereby inhibiting cuproptosis and driving LUAD progression. These findings clarify a novel epigenetic mechanism underlying LUAD and highlight the UHRF1/FDX1 axis as a potential therapeutic target.
Organisms adapt to novel environments using changes to genome, gene expression, and protein functions. This study focused on changes that had occurred when a fungal pathogen previously encountered hosts that differed only at the major histocompatibility complex (MHC) region, loci that control immune recognition during the adaptive immune response. To investigate how this fungal pathogen adapted to the host environment, next generation sequencing data were examined from strains of Cryptococcus neoformans (C. neoformans) that had been previously passaged eight times through congenic mice that specifically differed at the MHC locus, H2. Transcript levels and the genomic sequence for each post-adapted fungal strain were examined to identify molecular adaptation strategies via heritable gene expression changes (epigenetic changes) and mutation (DNA changes). The post-adapted strains displayed repeated changes in transcript levels, as determined by RNA-sequencing. Some of these epigenetically regulated genes (ERGs) only occurred in strains passaged in MHC specific hosts, suggesting possible prior adaptations to specific host MHCs. To our knowledge, this is the first time ERGs have been reported as possible pathogen adaptations to specific host MHC alleles. Additionally, of the total 47 single nucleotide polymorphisms (SNPs) identified, 7 SNPs each were found in 2 or more fungal strains (of the 6 analyzed strains) passaged through different MHC congenic hosts, suggesting much of the fungal mutation-based adaptation was to the mouse host, and not MHC-specific. These data demonstrated that these passaged C. neoformans strains adapted to the MHC haplotype of a novel mammalian host environment primarily via epigenetic rather than mutation-based mechanisms.
Male meiosis is the developmental process in which germ cells halve their chromosome number while continuing toward sperm formation. This review focuses on mechanistic studies of male meiosis in mouse and develops an epigenetic framework for this transition, centered on two key concepts. First, the foundation of meiosis is established ahead of meiotic entry. Prior to meiosis, germ-cell genes are poised and chromosomes are organized to support the upcoming meiotic program. Stage-specific signals and transcription factors then act on this prepared state to initiate meiotic gene expression. Second, meiosis reorganizes the germline in preparation for the post-meiotic spermiogenic program. In early prophase, nascent transcription remains low, allowing chromosomes to reorganize for recombination. Later, pachytene spermatocytes undergo an autosomal transcriptomic burst required for meiotic progression and post-meiotic development, while retrotransposon expression is controlled and unsynapsed sex chromosomes are silenced. Together, these concepts frame male meiosis as both the execution of a prepared developmental process and a critical window during which the germline genome is reshaped. This epigenetic trajectory connects gene regulation, chromosome organization, genome defense, and developmental timing to ensure production of functional sperm.
DNA methylation is a crucial epigenetic modification whose abnormal alterations are closely associated with various tumors and are considered potential biomarkers for cancer diagnosis. However, achieving highly sensitive and selective detection of low-abundance methylated DNA in complex biological samples remains a significant challenge. This study developed a functionalized glass micropipette electrochemical sensing strategy based on the enzyme-responsive signal switching effect for highly sensitive detection of methylated DNA. This system utilizes glass micropipettes modified with polydopamine nanotubes (PDA-NTs) to construct an ion-transport interface, where the capture probe (cpDNA) is immobilized to achieve specific recognition of target sequences. The detection mechanism relies on sequence differences introduced by sodium bisulfite conversion and the selective cleavage action of the nucleic acid exonuclease Exo III: upon forming stable double-stranded structures with the cpDNA, methylated DNA triggers Exo III-mediated structural changes at the interface. This modulates ion transport behavior within the channels, generating a current response that switches from "Off" to "On", enabling effective differentiation between methylated and unmethylated DNA. This sensing system exhibits excellent linear response to methylated DNA within the 1 aM-100 fM range, with a detection limit as low as 8.5 aM, and enables reliable detection in 10% human serum samples. This strategy achieves sensitive detection through an enzyme-responsive signal switch without requiring PCR amplification or complex labeling procedures, providing a simple and effective method for rapid analysis of DNA epigenetic modifications.
Postpartum depression (PPD) can be predicted by biomarkers of 3rd trimester methylation at two estrogen-responsive genes (TTC9B, HP1BP3), but the mechanism(s) by which these epigenetic changes lead to PPD are unknown. We investigated whether clinical characteristics (psychiatric histories, depression onset, stress/anxiety/trauma) differ between those with (BM+) and without (BM-) these biomarkers of PPD risk. Participants (N = 206) completed clinical diagnostic interviews and stress, anxiety, and trauma questionnaires at up to 7 visits during pregnancy and postpartum. Biomarker status was determined using 3rd trimester blood samples. Linear mixed effects models compared outcomes between biomarker groups (positive/negative). Mediation models assessed the average causal mediation effect of anxiety on the relationship between biomarker status and PPD. BM+ individuals were more likely to 1) have a prior history of generalized anxiety (X2 = 10.06, p = .003) and bipolar II disorder (X2 = 7.68, p = .01), 2) develop PPD (X2 = 3.97, p = .04), and 3) be depressed during both pregnancy and postpartum (X2 = 6.52, p = .02). BM+ individuals scored higher on the perinatal anxiety screening scale (PASS, p = .006), perceived stress scale (PSS, p = .001), and state-trait anxiety inventory (STAI)-trait subscale (p = .02). Anxiety outcomes on the PASS (95% CI: 0.01-0.10, p = .004), PSS (95% CI: 0.007-0.10, p = .03), and STAI-State (95% CI: -0.001-0.06, p = .06) mediated the relationship between biomarker status and PPD development. Findings suggest distinct clinical phenotypes between BM+ and BM- PPD, with BM+ individuals displaying significantly higher anxiety/stress, which may contribute to their higher risk of developing PPD. This presents an opportunity to investigate mechanisms in more homogenous groups based on biomarker status.
Aging is a biologically tractable process. Telomerase reverse transcriptase (TERT) has emerged as an upstream regulator coordinating several hallmarks of aging across preclinical models. Beyond maintaining telomeres, TERT influences mitochondrial health, epigenetic regulation, inflammation and stem cell function. Multiple translational strategies are being explored to modulate TERT. In mice and human cell models, restoration of physiological-range TERT expression characteristic of younger cells, or related telomere-focused interventions, has been associated with improvements in selected age-related phenotypes without a detectable increase in cancer. Simultaneously, human genetics links common variation in the TERT locus to increased risk of several cancers, underscoring the need for careful mechanistic and long-term safety evaluations. Together, mounting evidence indicates that TERT occupies an important position in aging biology with the potential to affect healthspan. This Perspective reviews current evidence for TERT's canonical and noncanonical roles and outlines a cautious therapeutic framework for evaluating TERT-directed geroprotective strategies.
The cohesin complex structures the interphase genome of human cells by extruding loops and organizing topologically associating domains (TADs), yet how chromatin state regulates cohesin-chromatin interactions remains unclear. Here, we show that histone hyperacetylation induced by trichostatin A (TSA) selectively disrupts short-range intra-TAD interactions while largely preserving CTCF-anchored loops. These distinct responses define two functional cohesin populations: a TSA-sensitive pool associated with dynamic loop extrusion, and a TSA-resistant pool at CTCF sites maintained by topological entrapment. Using a semi-in vitro system with TEV-cleavable RAD21, we demonstrate that hyperacetylation increases the sensitivity of CTCF-anchored loops to cohesin ring cleavage, supporting a topological basis for their stability. We further identify a TSA-sensitive cohesin fraction at CTCF sites, suggesting transient, non-encircling intermediates. Together, our results reveal that cohesin exists in distinct biochemical states that differentially regulate chromatin loop stability and responsiveness to epigenomic perturbation.
Plants frequently encounter recurring, sequential and combined environmental stresses, yet their adaptive capacity cannot be explained solely by immediate signalling and short-term acclimation. Increasing evidence indicates that prior stress exposure can leave molecular, metabolic and physiological imprints that alter the magnitude, speed and quality of later responses, thereby giving rise to stress memory and adaptive plasticity. In plants, these persistent states are increasingly linked to epigenetic regulation, including changes in chromatin accessibility, histone modifications, DNA methylation, RNA-directed DNA methylation and non-coding RNA-mediated control. However, stress memory is not determined by chromatin regulation alone. It is also shaped by metabolic and cellular reprogramming involving osmolyte accumulation, redox buffering, energy redistribution, protein quality control, autophagy, selective protein turnover and membrane remodelling, all of which help sustain cellular homeostasis during stress and recovery. In parallel, chloroplasts, mitochondria and the endoplasmic reticulum act as stress-sensitive organelles that relay their functional state to the nucleus through retrograde signalling, while long-distance systemic communication mediated by reactive oxygen species, calcium waves, electrical and hydraulic signals, hormones and peptides coordinates whole-plant acclimation. This review synthesizes these layers into a unified framework and argues that plant resilience under fluctuating environments depends on the interaction between stress memory, metabolic plasticity, organelle-derived signalling and systemic acquired acclimation. Particular attention is given to the distinction between transient acclimation and true memory, the balance between maintenance and resetting of stress-induced states and the developmental and fitness trade-offs associated with persistent preparedness. This review also highlights major gaps that continue to limit the field, including the lack of standardized criteria for defining stress memory, insufficient causal validation of epigenetic marks, weak integration of chromatin and metabolic states with whole-plant phenotypes, and the limited translation of memory-associated mechanisms into crop performance under realistic field conditions. Overall, this review provides a comprehensive framework for understanding how plants not only respond to stress, but also encode, retain and deploy information from prior exposure to optimize subsequent adaptation.
Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive liver disease driven by metabolic stress, inflammation, and fibrosis, with limited effective therapies. Thioredoxin-interacting protein (TXNIP) links hyperglycemia and oxidative stress to NLRP3 inflammasome activation, but the epigenetic mechanisms sustaining TXNIP induction in diabetic MASH remain unclear. Bromodomain-containing protein 4 (BRD4) is an epigenetic reader that promotes inflammatory transcription through chromatin engagement. Here, we examined whether BRD4-associated regulation of TXNIP contributes to diabetic MASH and evaluated LT052, a BD1-biased BET bromodomain inhibitor with preferential BRD4 BD1 activity, in a streptozotocin-accelerated dietary rat model. Diabetic MASH caused severe steatohepatitis, fibrosis, insulin resistance, oxidative stress, NF-κB activation, TXNIP induction, and NLRP3 inflammasome activation. These changes were accompanied by increased BRD4 occupancy at the TXNIP promoter and elevated total hepatic histone H3 acetylation (Ac-H3K9). LT052 markedly improved liver histopathology, metabolic control, redox balance, and inflammatory outcomes, while reducing TXNIP expression, inflammasome activation, and downstream pyroptotic signaling. Mechanistically, LT052 reduced BRD4 occupancy at the TXNIP promoter and decreased total hepatic Ac-H3K9 without altering total BRD4 expression or nuclear BRD4 immunostaining, consistent with reduced BRD4-associated promoter engagement rather than altered BRD4 abundance or localization. Integrated analyses showed broad, dose-dependent improvement across MASH-relevant endpoints. These findings support further investigation of BD1-biased BET inhibition with LT052 as a therapeutic strategy for diabetic MASH.
Ependymoma-like tumor with mesenchymal differentiation (ELTMD) is a recently proposed, but not yet formally defined, entity that is not recognized in the 2021 World Health Organization (WHO) classification of central nervous system tumors. Although it shares molecular features, such as ZFTA fusion, with ependymomas, it exhibits distinct histopathological and epigenetic profiles. Herein, we report the case of a 5-year-old girl with a supratentorial tumor harboring the ZFTA::NCOA2 fusion. Histopathology revealed atypical features including mesenchymal and undifferentiated components, which overlapped with those of ependymomas. DNA methylation profiling using two independent classifiers (DKFZ and NIH) yielded no matches, indicating that the tumor did not belong to any recognized CNS class. The failure of subclass assignment by both classifiers suggests that ELTMD represents a potentially epigenetically distinct subgroup. Despite being unclassifiable by the current WHO criteria, the tumor shared features with previously reported ELTMDs, supporting its recognition as an emerging tumor. This highlights the need for additional cases to refine the diagnosis, classification, and future therapeutic strategies.
Periodontitis (PD) is a complex inflammatory condition driven by the interplay of microbial, genetic, epigenetic, and environmental factors. While bacterial biofilms are regarded as the primary cause, growing evidence underscores the significant role of genetic predisposition in determining susceptibility to the disease, its progression, and treatment outcomes. This review explores the genetic polymorphisms of PD, focusing on genes related to inflammatory mediators, immune responses, antimicrobial peptides, matrix metalloproteinases, and vitamin D receptor pathways. Key epigenetic mechanisms including DNA methylation, histone modifications, non-coding RNAs, and emerging RNA methylation pathways are explored in their roles in modulating inflammation, tissue destruction, bone metabolism, and interactions between the host and microbes. Advances in transcriptomic technologies, particularly RNA sequencing, have enhanced our ability to identify molecular biomarkers and cell-specific gene expression profiles associated with disease severity and responses to treatment. The potential for leveraging genetic and epigenetic profiling presents an exciting avenue for personalized periodontal care, including the use of epigenetic therapies targeting pathways involved in inflammation and tissue regeneration. Nonetheless, the current body of evidence has limitations. These include significant variability across studies, inconsistent disease classification systems, small sample sizes, and a predominance of preclinical or exploratory research. Many biomarkers and therapeutic targets proposed to date require further validation before they can be routinely applied in clinical practice. While integrating genetic, epigenetic, transcriptomic, and clinical data holds promise for advancing precision periodontology, rigorous large-scale, and multicenter studies are essential to confirm clinical applicability, validate biomarkers, and facilitate their incorporation into evidence-based treatment protocols.
DNA G-quadruplex structures (G4s) are noncanonical nucleic acid structures that play crucial roles in gene transcription regulation, particularly when located within promoter regions. Tissue-specific gene expression underlies the development and functional specialization of multicellular organisms. However, the potential role of G4s in tissue-specific transcriptional regulation remains largely unexplored. In this study, we conducted an integrative analysis of G-quadruplex (G4) distribution and function in the silkworm brain and fat body, two substantially differentiated tissues in terms of structure and function, using G4-CUT&Tag, ATAC-seq, RNA-seq, and histone modification datasets. We found that promoter G4s were highly enriched in regions of open chromatin and active histone modification, and that G4 folding showed a correlation with transcriptional activation in a tissue-specific manner. Even at identical genomic DNA sequences, G4 folding patterns differed markedly between the brain and fat body and were associated with tissue-specific gene expression profiles. Genes marked by brain-specific G4s were enriched in neural pathways, whereas genes with fat body-specific G4s were enriched in metabolic pathways, closely aligning with the physiological roles of each tissue. Moreover, chemical stabilization of G4s by pyridostatin disrupted gene expression and impaired tissue development, including neurogenesis in the brain and lipid metabolism in the fat body. Our results suggest that G4s may function as dynamic epigenetic modulators that shape tissue-specific gene expression and coordinate functional differentiation in insects.
Hypertension is a major risk factor for cardiovascular disease and alters the mechanical microenvironment of the vascular wall and target organs. Key mechanical disturbances include disturbed shear stress, excessive circumferential stretch, elevated hydrostatic pressure, and increased extracellular matrix stiffness. These forces are sensed by multiple classes of mechanosensors, including mechanosensitive ion channels, integrin-based adhesion complexes, G protein-coupled receptors, primary cilia, baroreceptor afferents, and nuclear mechanosensing structures. Activation of these sensors engages interconnected Ca²⁺-dependent, RhoA/Rho-associated protein kinase, mitogen-activated protein kinase, phosphoinositide 3-kinase/Akt/endothelial nitric oxide synthase, Yes-associated protein/transcriptional coactivator with PDZ-binding motif, redox-sensitive, inflammatory, and mechano-epigenetic pathways. This review summarizes how altered mechanotransduction may contribute to endothelial dysfunction, vascular smooth muscle cell phenotypic switching, vascular remodeling, and cardiac and renal target-organ injury in hypertension. Mechanotransduction is unlikely to represent a universal initiating cause of hypertension. Rather, it should be viewed as a context-dependent set of adaptive and maladaptive responses that varies according to cell type, vascular bed, mechanical stimulus, disease stage, and experimental model. Physiological mechanotransduction helps maintain vascular homeostasis and baroreflex function, whereas sustained pathological loading may amplify oxidative stress, inflammation, fibrosis, and vascular stiffening. However, most direct mechanistic evidence derives from cultured cells and animal models, and human genetic, tissue, biomarker, and interventional data remain limited. Conventional antihypertensive therapy therefore remains the foundation of clinical management, whereas direct targeting of mechanosensors or downstream mechanotransduction pathways remains experimental and requires stronger human validation.
RNA interference (RNAi) in nematodes is amplified through the generation of secondary small interferring RNA (siRNA) from products of primary siRNA cleavage. This process requires RDE-3, a unique ribonucleotidyltransferase that adds a poly(UG) tail of alternating U and G nucleotides without a template. Here we demonstrated using in vitro enzymatic assays that RDE-3 is intrinsically specific for substrate combinations that correctly extend the pUG tail and optimized for effective pUGylation in vivo. Specificity for cognate substrate pairs (3'-G RNA with UTP or 3'-U RNA with GTP) was driven primarily by a faster turnover rate, whereas non-cognate GG or UU extensions were dramatically slower. RDE-3 could also extend 3'-A or 3'-C RNA substrates with GTP or UTP, allowing it to initiate pUGylation of primary RNAi products, but at slower rates and with little GTP/UTP preference. We established an assay where products of both 3'-G and 3'-U RNA substrates in a reaction with GTP and UTP were followed simultaneously. We found that pUG extension was optimal and most accurate under conditions where GTP/UTP concentrations corresponded to their relative KMNTP values and typical cellular conditions.