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PubMed2006

CUL4-DDB1 ubiquitin ligase interacts with multiple WD40-repeat proteins and regulates histone methylation.

The CUL4-DDB1-ROC1 ubiquitin E3 ligase regulates cell-cycle progression, replication and DNA damage response. However, the substrate-specific adaptors of this ligase remain uncharacterized. Here, we show that CUL4-DDB1 complexes interact with multiple WD40-repeat proteins (WDRs) including TLE1-3, WDR5, L2DTL (also known as CDT2) and the Polycomb-group protein EED (also known as ESC). WDR5 and EED are core components of histone methylation complexes that are essential for histone H3 methylation and epigenetic control at K4 or K9 and K27, respectively, whereas L2DTL regulates CDT1 proteolysis after DNA damage through CUL4-DDB1 (ref. 8). We found that CUL4A-DDB1 interacts with H3 methylated mononucleosomes and peptides. Inactivation of either CUL4 or DDB1 impairs these histone modifications. However, loss of WDR5 specifically affects histone H3 methylation at K4 but not CDT1 degradation, whereas inactivation of L2DTL prevents CDT1 degradation but not histone methylation. Our studies suggest that CUL4-DDB1 ligases use WDR proteins as molecular adaptors for substrate recognition, and modulate multiple biological processes through ubiquitin-dependent proteolysis.

Adaptor Proteins, Signal Transducing↗
PubMed1978

Histone composition of a chromatin fraction containing ribosomal deoxyribonucleic acid isolated from the macronucleus of Tetrahymena pyriformis.

The histone compositions of a chromatin fraction containing ribosomal DNA and of the remaining macronuclear chromatin of Tetrahymena pyriformis was analysed by gel electrophoresis. These chromatin fractions were used as models for transcriptionally active and inactive chromatin respectively. The extent of histone modification, as indicated by the distribution of histone between differently charged subspecies in acid-urea gels, is not grossly different in the two chromatin fractions. However, histone H1 is present, but may be differently modified in the two chromatin fractions. The histone/DNA ratio in ribosomal chromatin, measured after sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of samples of chromatin, was found to be the same whether chromatin was extracted from growing or stationary organisms, and to be approx. 40% of this ratio in the remaining macronuclear chromatin. The implications of these results for the possible structure of transcriptionally active chromatin are discussed.

Animals↗
PubMed2006

Nucleosome displacement in transcription.

Recent reports reinforce the notion that nucleosomes are highly dynamic in response to the process of transcription. Nucleosomes are displaced at promoters during gene activation in a process that involves histone modification, ATP-dependent nucleosome remodeling complexes, histone chaperones and perhaps histone variants. During transcription elongation nucleosomes are acetylated and transferred behind RNA polymerase II where they are required to suppress spurious transcription initiation within the body of the gene. It is becoming increasingly clear that the eukaryotic transcriptional machinery is adapted to exploit the presence of nucleosomes in very sophisticated ways.

Animals↗
PubMed2005

Schizosaccharomyces pombe mst2+ encodes a MYST family histone acetyltransferase that negatively regulates telomere silencing.

Histone acetylation and deacetylation are associated with transcriptional activity and the formation of constitutively silent heterochromatin. Increasingly, histone acetylation is also implicated in other chromosome transactions, including replication and segregation. We have cloned the only Schizosaccharomyces pombe MYST family histone acetyltransferase genes, mst1(+) and mst2(+). Mst1p, but not Mst2p, is essential for viability. Both proteins are localized to the nucleus and bound to chromatin throughout the cell cycle. Deltamst2 genetically interacts with mutants that affect heterochromatin, cohesion, and telomere structure. Mst2p is a negative regulator of silencing at the telomere but does not affect silencing in the centromere or mating type region. We generated a census of proteins and histone modifications at wild-type telomeres. A histone acetylation gradient at the telomeres is lost in Deltamst2 cells without affecting the distribution of Taz1p, Swi6p, Rad21p, or Sir2p. We propose that the increased telomeric silencing is caused by histone hypoacetylation and/or an increase in the ratio of methylated to acetylated histones. Although telomere length is normal, meiosis is aberrant in Deltamst2 diploid homozygote mutants, suggesting that telomeric histone acetylation contributes to normal meiotic progression.

Acetylation↗
PubMed2006

The generation and recognition of histone methylation.

The posttranslational modification of histone proteins via methylation has important functions in gene activation, transcriptional silencing, establishment of chromatin states, and likely many aspects of DNA metabolism. The identification of numerous effector protein domains with the capability of binding methylated histones has significantly advanced our understanding of how such histone modifications may exert their biological effects. Here, we summarize aspects of the generation of arginine and lysine methylation marks on core histones, the characterization of the protein modules that interact with them, and how histone methylation cross-talks with other modifications.

Amino Acid Sequence↗
PubMed2003

Acetylation and methylation in nuclear receptor gene activation.

Activation of hormone target genes requires chromatin remodeling and histone modifications. The properties of the two PRMT coactivators. PRMT1 and CARM1, are compared in Table I. One can envision many scenarios in which histone arginine methylation contributes to transcriptional regulation. For example, it could be analogous to histone H3 K4 methylation by Set9, which blocks the HDAC NuRD complex from association and simultaneously impairs Suv39 h 1-mediated methylation at K9 of H3 (H3-K9). As a result, H3 K4 methylation by Set9 potentiates transcriptional activation. Histone arginine methylation might also promote or antagonize other histone-modifying enzymes. It has been shown that PRMT1-methylated histone H4 becomes a better substrate for p300 and, conversely, the acetylated histones are poor substrates for methylation by PRMT1. As for CARM1, acetylation of multiple lysines within histone H3 facilitates arginine methylation of by CARM1. Since PRMT1 and CARM1 methylate H4 and H3 tails, respectively, and each contributes to activation of the nuclear receptor response, it implicates the "histone code" as the physical template of hormone signaling. However, it remains to be resolved whether p160 family coactivators simultaneously recruit CARM1 and PRMT1 to specific target genes, and the order of the series of modifications on individual histone tails in vivo. Time-course studies of [table: see text] cofactor recruitment by ChIPs will be necessary to decipher the modification patterns. Another useful approach to analyze the function of NR cofactors on target gene transcription is the chromatin-dependent in vitro transcription system. As increasing amounts of evidence indicate that one HAT can be acetylated by another HAT, or methylated by HMT, it would not be surprising that transcription factors and their coactivators are bona fide substrates for protein modification.

ADP-ribosyl Cyclase↗
PubMed2003

Differential transcription factor occupancy but evolutionarily conserved chromatin features at the human and mouse M-CSF (CSF-1) receptor loci.

The c-FMS gene encodes the macrophage colony-stimulating factor receptor (M-CSFR or CSF1-R), which is a tyrosine kinase growth factor receptor essential for macrophage development. We have previously characterized the chromatin features of the mouse gene; however, very little is known about chromatin structure and function of the human c-FMS locus. Here we present a side-by-side comparison of the chromatin structure, histone modification, transcription factor occupancy and cofactor recruitment of the human and the mouse c-FMS loci. We show that, similar to the mouse gene, the human c-FMS gene possesses a promoter and an intronic enhancer element (c-fms intronic regulatory element or FIRE). Both elements are evolutionarily conserved and specifically active in macrophages. However, we demonstrate by in vivo footprinting that both murine and human c-FMS cis-regulatory elements are recognised by an overlapping, but non-identical, set of transcription factors. Despite these differences, chromatin immunoprecipitation experiments show highly similar patterns of histone H3 modification and a similar distribution of chromatin modifying and remodelling activities at individual cis-regulatory elements and across the c-FMS locus. Our experiments support the hypothesis that the same regulatory principles operate at both genes via conserved cores of transcription factor binding sites.

3T3 Cells↗
PubMed2026

Integrated analysis of ATAC-seq and RNA-seq reveals the TCP-ARF molecular module related to pathogenic process of phytoplasma infection in Paulownia fortunei.

BACKGROUND: Witches’ broom is an important disease of the Paulownia fortunei. Understanding the pathogenesis of witches’ broom is a prerequisite for its prevention and control. Phytoplasma is the pathogen of Paulownia witches’ broom. RESULTS: We investigated the changes in chromatin accessibility before and after phytoplasma infection in Paulownia fortunei by analyzing the DNA accessibility (ATAC-seq). In phytoplasma-infected P. fortunei (PFI) compared to healthy samples (PF), the closed regions of chromatin(1187 regions) were three times more than the open regions (352 regions). Fifty one percent of the accessible chromatin regions were overlapped with either H3K27ac or H3K9ac peaks. The closed regions were enriched in the conserved motif TGGGC[CT] that is recognized by the TCP transcription factor family. The closed regions in PFI are intersected with ARF family gene locus. The gene PfARF3 was verified to interact with the PfTCP23 transcription factor. The PfTCP23 was predicted to be interacted with the effector pawb44 in the pathogen of phytoplasma. CONCLUSIONS: The phytoplasma infection in P. fortunei is involved in the chromatin changes of the DNA accessibility and histone modification. The binding regions of TCP23 were found to be changed mostly in the accessibility between PFI and PF. The TCP-ARF module was found to be the possible regulatory module inducing the crinkled leaf trait.

RNA-Seq↗
PubMed2025

Chromatin Immunoprecipitation for Standard, Rare, or Weakly Binding Proteins.

Various proteins interact with specific genome regions, playing crucial roles in gene regulation. Chromatin Immunoprecipitation (ChIP) is the most commonly used method to study protein-DNA interactions in vivo. By combining ChIP with high-throughput sequencing, ChIP-seq allows for studying the genome-wide localization of proteins. Although several ChIP protocols are available for plant tissues, they are primarily designed for histone modifications and abundant proteins with high DNA-binding affinity, which are considered as the "standard targets." Here we describe a ChIP protocol for plant tissues not only optimized for the standard targets but also adapted for proteins with low abundances or weak DNA-binding ability. Successful execution of the protocol enables reliable generation of DNA templates for quantitative PCR or libraries for next-generation sequencing, which makes it an effective tool for analyzing genomic interactions of a wide range of proteins.

Chromatin Immunoprecipitation↗
PubMed2026

L-glutamine supplementation improves porcine sperm quality and early embryo development during in vitro fertilization.

L-glutamine (Gln), as a key additive in porcine sperm capacitation medium and in vitro fertilization (IVF) systems, has been shown to significantly improve sperm motility and survival rates. However, its precise roles during porcine IVF and subsequent early embryonic development remain elusive. This study utilized an IVF model in pigs to investigate the effects of glutamine on sperm quality and embryonic development. We found that Gln supplementation during sperm treatment significantly improved sperm quality, as evidenced by reduced reactive oxygen species (ROS) production and early apoptosis, while enhancing calcium ion levels and endoplasmic reticulum activity. Supplementing glutamine during embryo culture reduced polyspermy rates, promoted zygotic genome activation (ZGA) and accumulation of 5-ethynyluridine (EU) and histone modifications (H3K4me3 and H3K27ac) at the two-cell and four-cell stages, increased blastocyst formation rates and total cell numbers, while simultaneously reducing DNA damage and early apoptosis during the blastocyst stage. In summary, these findings demonstrate that Gln enhances porcine IVF outcomes by improving sperm quality, reducing polyspermy, and facilitating early embryonic development, thereby providing a basis for optimizing culture systems.

Animals↗
PubMed2025

Genetic and chromatin regulation of Pvt1 monoallelic expression.

While most genes are equivalently expressed on both alleles, genes with random monoallelic expression (RME) stably maintain expression from only one allele, but the mechanisms and consequences of RME remain unclear. We performed allele-specific RNA sequencing (RNA-seq) on ∼100 F1 hybrid neural progenitor cell (NPC) clonal lines to reveal the extent of autosomal RME (aRME). Of the 287 aRME genes, Pvt1, an oncogenic long non-coding RNA, is an aRME with a genetic bias. In the absence of genetic differences, Pvt1 undergoes balanced aRME. Pvt1 monoallelic expression is maintained by allele-specific active and repressive histone modifications, opposed to DNA methylation. Additionally, we provide a two-step mechanism for the initiation of aRME and demonstrate that Pvt1 monoallelic expression results in a growth phenotype due to the interplay with Myc. These findings provide insight into how genetic differences can skew a stochastic process, resulting in monoallelic expression with a phenotypic consequence in early development.

Chromatin↗
PubMed2026

Epigenetic alterations in rheumatoid arthritis: multilayer mechanisms and translational opportunities.

Rheumatoid arthritis (RA) is a chronic inflammatory disease driven by immune dysregulation, in which genetic susceptibility and environmental exposures promote persistent synovitis, progressive joint damage, and systemic comorbidities. Recent epigenomic studies show several recurring abnormalities. Many RA susceptibility variants lie outside protein-coding sequence and map to immune-cell and synovial fibroblast regulatory elements, linking inherited risk to enhancer activity, methylation quantitative trait effects, and distal gene control. Blood-based epigenome-wide association studies identify disease-associated DNA methylation signatures, but these signals require careful control for leukocyte composition, smoking, treatment exposure, and disease stage. RA fibroblast-like synoviocytes also display stable methylome remodeling, including relative hypomethylation at loci involved in inflammation, migration, matrix degradation, and apoptosis resistance, while TET3-associated 5-hydroxymethylcytosine has emerged as a functional contributor to chemokine production and invasive stromal behavior. Histone modifications, chromatin accessibility, and 3D genome organization define pathogenic regulatory states and connect non-coding risk loci to effector genes in immune and stromal compartments. Finally, miRNAs, lncRNAs, circRNAs, snoRNAs, extracellular RNAs, and m6A-related pathways add post-transcriptional and chromatin-linked layers with potential biomarker value. We synthesize these findings and discuss translational opportunities for diagnosis, stratification, flare monitoring, and therapeutic targeting, while emphasizing incomplete replication, uneven evidence across epigenetic layers, biospecimen variability, and the need for causal, longitudinal, cell-type-resolved validation.

Humans↗
PubMed2026

Epigenetic regulation of transgenes.

Gene therapy holds significant potential for treating genetic disorders, but the use of viral vectors is limited by factors such as immunogenicity, payload capacity, and high manufacturing costs. Nonviral gene delivery (NVGD) using plasmid DNA presents an attractive alternative; however, it typically provides a limited magnitude or duration of transgene expression. One potential reason for these shortcomings is the host cell's epigenetic regulation mechanisms, which can silence both viral and nonviral transgenes. Specifically, when foreign DNA enters the nucleus, it is detected by nuclear DNA sensors, such as IFI16, which initiate the assembly of a "restrictosome" or nuclear domain 10 (ND10) body. This multiprotein complex contains several components, such as PML, Speckled Proteins (e.g., SP100), DAXX, and ATRX that act as a scaffold for recruiting various epigenetic modifiers that subsequently deposit repressive histone modifications like H3K9me3 and H3K27me3 on the transgene chromatin. These marks induce DNA methylation and the subsequent condensation of plasmids or episomes into heterochromatin, which represses transgene expression. Alternatively, unmethylated CpG motifs in bacterial plasmid DNA can trigger innate immune responses in the cytosol, but this review will specifically focus on the detailed mechanisms of epigenetic regulation responsible for silencing plasmid DNA within the host cell nucleus. Addressing these nuclear defense mechanisms, potentially through strategies that manipulate DNA methylation or inhibit restrictosome activity, is crucial for advancing the development of safe, effective, and long-lasting plasmid viral and non-viral gene therapies.

Epigenesis, Genetic↗
PubMed2026

AI-Based 3D Heterogeneous Network Model for Functional Prediction of Epigenetics.

Human biology and diseases are the result of constantly evolving processes within an intricately complex molecular network of interactions, such as epigenetic regulation. Epigenetics refers to heritable changes in gene expression that occur without alterations to the underlying DNA sequence. These changes, driven by mechanisms such as DNA methylation, histone modifications, and noncoding RNAs, play critical roles in regulating chromatin structure and gene activity. Epigenetic regulation offers valuable insights into biological systems, and when integrated with sophisticated analyses, it enables us to gain insights into gene regulation and cellular behavior. Here, we describe an artificial intelligence (AI)-based model that is capable of generating 3-dimensional (3D) heterogeneous network by integrating multimodal data for the functional prediction of epigenetic mechanisms, emphasizing its applications in medicine, developmental biology, and personalized therapeutics. Heterogeneous networks in biology are powerful tools for understanding the complex interactions and interdependencies within biological systems. Key advancements in AI and multiomics data integration have propelled this field, offering new insights into disease mechanisms, biomarker discovery, and therapeutic interventions.

Epigenesis, Genetic↗
PubMed2025

Constructing epigenetic regulatory landscapes of plant lncRNAs-an exploration utilizing the novel specialized platform PERlncDB.

Long non-coding RNAs (lncRNAs), once overlooked as transcriptional byproducts, are now recognized for their crucial roles in plant growth, development, and stress responses, with increasing focus on their epigenetic regulation. However, studies investigating epigenomic signals to explore the functions of lncRNAs in plants remain relatively limited. This study collected a comprehensive dataset of over 160 000 high-quality lncRNAs from 19 representative plant species and integrated 6715 ChIP-seq, BS-seq, and RNA-seq datasets to analyze epigenomic patterns at lncRNA loci. Results showed elevated DNA methylation in lncRNA regions. The highest levels occurred in transposable element-associated lncRNAs. Additionally, activating histone modifications at lncRNA loci showed tissue specificity, with epigenetic preferences differed from those at protein-coding gene (PCG) loci. Differential site analysis in epigenetic mutants further highlighted the selective regulation of lncRNA loci by specific epigenetic factors. To facilitate research, we developed PERlncDB, a platform that provides species-specific lncRNA browsing, epigenetic annotation, cross-species conservation analysis, and visualization of epigenomic landscapes. Case studies on MARS and LINC-AP2 emphasized the platform's utility. Conserved epigenetic mechanisms regulating lncRNAs across species, exemplified by a syntenic conserved MET1-regulated lncRNA pair in Arabidopsis and tomato, suggested the stability of regulatory mechanisms underlying lncRNA functions. This work provides critical insights and resources for understanding plant lncRNA epigenetic regulation.

RNA, Long Noncoding↗
PubMed2006

Epigenetic maintenance of the vernalized state in Arabidopsis thaliana requires LIKE HETEROCHROMATIN PROTEIN 1.

Vernalization is the process by which sensing a prolonged exposure to winter cold leads to competence to flower in the spring. In winter annual Arabidopsis thaliana accessions, flowering is suppressed in the fall by expression of the potent floral repressor FLOWERING LOCUS C (FLC). Vernalization promotes flowering via epigenetic repression of FLC. Repression is accompanied by a series of histone modifications of FLC chromatin that include dimethylation of histone H3 at Lys9 (H3K9) and Lys27 (H3K27). Here, we report that A. thaliana LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) is necessary to maintain the epigenetically repressed state of FLC upon return to warm conditions typical of spring. LHP1 is enriched at FLC chromatin after prolonged exposure to cold, and LHP1 activity is needed to maintain the increased levels of H3K9 dimethylation at FLC chromatin that are characteristic of the vernalized state.

Arabidopsis↗
PubMed2007

Altered protamine expression and diminished spermatogenesis: what is the link?

During the elongating spermatid stage of spermiogenesis, human sperm chromatin undergoes a complex transition in which histones are extensively replaced by protamines in a carefully regulated transition including histone modifications and intermediate and temporary replacement of the histones by sperm-specific transition proteins. The replacement of most histones by protamines 1 and 2 facilitates a high order of chromatin packaging necessary for normal sperm function and may also be necessary for DNA silencing and imprinting changes within the sperm cell. Protamines 1 and 2 are usually expressed in nearly equal quantities, but elevated or diminished protamine 1/protamine 2 ratios are observed in some infertile men and is often associated with severe spermatogenesis defects. Human and animal studies demonstrate that expression of the protamine proteins is uniquely regulated by transcription/translation factors, including storage of the mRNA in ribonucleoprotein (RNP) particles composed of the mRNA, transcription factors and a kinesin molecule necessary for transport of the RNP to the cytoplasm and removal of transcriptional activators from the nucleus. Recent studies indicate that most patients with abnormal protamine protein levels have elevated levels of protamine transcript in the mature sperm cell, indicating a possible defect in transcription or translation. The regulation of protamine expression is unique and includes several possible mechanisms which may be responsible for dysregulation of protamine expression and concurrent broad spectrum defects in spermatogenesis. We suggest two hypotheses: (i) that abnormal protamine expression is indicative of a generalized defect in mRNA storage and/or translation which affects other mRNA transcripts or (ii) that protamines may act as a checkpoint of spermatogenesis.

Animals↗
PubMed2005

siRNA induced transcriptional gene silencing in mammalian cells.

Epigenetics is the study of meiotically and mitotically heritable changes in gene expression which are not coded for in the DNA. Three distinct mechanisms appear to be intricately related and implicated in initiating and/or sustaining epigenetic modifications; DNA methylation, RNA-associated silencing, and histone modifications. It has recently become clear in human cells that RNA plays a far more profound and complex role in regulating the expression of the gene. This regulatory effect is through RNA-associated silencing, can be transcriptional in nature, and is operable through an RNA interference based mechanism (RNAi) that is specifically mediated by small-interfering RNAs (siRNAs). Specifically, the recent observations by both our groups that siRNAs can silence target genes at the level of the chromatin in mammalian cells. We discuss here siRNA mediated transcriptional gene silencing and directed DNA methylation as well as the putative mechanism involved in human cells. Undoubtedly, the ramifications from this paradigm shift of RNA regulating the expression of the gene are immeasurable both therapeutically (i.e., directed control of a genes expression) and biologically in understanding the evolution of the cell.

Animals↗