Histone and chromatin cross-talk

Interplay between DOT1L and HDAC1 regulates Leishmania donovani infection in human THP-1 cells

Leishmania donovani, a protozoan parasite, causes visceral leishmaniasis. The parasite modifies the global gene expressions of the host genome, facilitating its survival within the host. Thus, the host epigenetic modulators play important roles in host-pathogen interaction and host epigenetic modification in response to infection. Previously, we had reported that the host epigenetic modulator, histone deacetylase 1 (HDAC1) expression was upregulated on Leishmania donovani infection. This upregulation led to the repression of host defensin genes in response to the infection. In this paper, we have investigated the interplay between the host DOT1L, a histone methyltransferase, and HDAC1 in response to Leishmania donovani infection. We show that the expression of DOT1L is upregulated both at transcript and protein level following infection leading to increase in H3K79me, H3K79me2, and H3K79me3 levels. ChIP experiments showed that DOT1L regulated the expression of HDAC1. Downregulation of DOT1L using siRNA resulted in decreased expression of HDAC1 and increased transcription of defensin genes and thereby, lower parasite load. In turn, HDAC1 regulates the expression of DOT1L on Leishmania donovani infection as downregulation of HDAC1 using siRNA led to reduced expression of DOT1L. Thus, during Leishmania donovani infection, an interplay between DOT1L and HDAC1 regulates the expression of these two histone modifiers leading to downregulation of defensin gene expression.

Epigenome editing technologies for discovery and medicine

Epigenome editing has rapidly evolved in recent years, with diverse applications that include elucidating gene regulation mechanisms, annotating coding and noncoding genome functions and programming cell state and lineage specification. Importantly, given the ubiquitous role of epigenetics in complex phenotypes, epigenome editing has unique potential to impact a broad spectrum of diseases. By leveraging powerful DNA-targeting technologies, such as CRISPR, epigenome editing exploits the heritable and reversible mechanisms of epigenetics to alter gene expression without introducing DNA breaks, inducing DNA damage or relying on DNA repair pathways.

Elevated histone deacetylase 10 expression promotes the progression of clear cell renal cell carcinoma by Notch-1-PTEN signaling axis

BACKGROUND

Clear cell renal cell carcinoma (ccRCC), the most common pathological subtype of kidney cancer, accounts for approximately 70% to 80% of all cases. Histone deacetylase 10 (HDAC10) belongs to the HDAC class IIb subgroup, one of the histone deacetylases (HDAC) family. Previous studies suggest that HDAC10 may regulate the development of multiple tumor types. The specific molecular mechanisms employed by HDAC10 in the etiology of ccRCC still need to be discovered.

METHODS

The analysis included examining HDAC10 expression levels and their clinical importance within a cohort of inpatients and ccRCC patients documented in the Tumor Genome Atlas (TCGA). Moreover, the biological functions and underlying molecular mechanisms of HDAC10 were investigated.

RESULTS

HDAC10 showed increased expression in ccRCC tumor tissues. Subsequent analysis revealed overexpression of HDAC10 was associated with advanced clinical phenotype and unfavorable prognosis. The absence of HDAC10 significantly decreased ccRCC cell proliferation and migration capabilities. Mechanistic research suggests that HDAC10 may promote RCC development by activating the Notch-1 pathway and downregulating PTEN expression levels.

CONCLUSION

In summary, HDAC10 can modulate critical biological processes in ccRCC, including proliferation, migration, and apoptosis. Notably, the Notch-1 pathway and PTEN serve as crucial signaling pathways and target genes through which HDAC10 regulates the progression of ccRCC. These findings offer a novel outlook for ccRCC treatment.

Normal distribution of H3K9me3 occupancy co-mediated by histone methyltransferase BcDIM5 and histone deacetylase BcHda1 maintains stable ABA synthesis in Botrytis cinerea TB-31

Abscisic acid (ABA) is a conserved and important "sesquiterpene signaling molecule" widely distributed in different organisms with unique biological functions. ABA coordinates reciprocity and competition between microorganisms and their hosts. In addition, ABA also regulates immune and stress responses in plants and animals. Therefore, ABA has a wide range of applications in agriculture, medicine and related fields. The plant pathogenic ascomycete B. cinerea has been extensively studied as a model strain for ABA production. Nevertheless, there is a relative dearth of research regarding the regulatory mechanism governing ABA biosynthesis in B. cinerea. Here, we discovered that H3K9 methyltransferase BcDIM5 is physically associated with the H3K14 deacetylase BcHda1. Deletion of Bcdim5 and Bchda1 in the high ABA-producing B. cinerea TB-31 led to severe impairment of ABA synthesis. The combined analysis of RNA-seq and ChIP-seq has revealed that the absence of BcDIM5 and BcHda1 has resulted in significant global deficiencies in the normal distribution and level of H3K9me3 modification. In addition, we found that the cause of the decreased ABA production in the ΔBcdim5 and ΔBchda1 mutants was due to cluster gene repression caused by the emergence of hyper-H3K9me3 in the ABA gene cluster. We concluded that the ABA gene cluster is co-regulated by BcDIM5 and BcHda1, which are essential for the normal distribution of the B. cinerea TB-31 ABA gene cluster H3K9me3. This work expands our understanding of the complex regulatory network of ABA biosynthesis and provides a theoretical basis for genetic improvement of high-yielding ABA strains.

Drivers of cancer metastasis - Arise early and remain present

Cancer and its metastases arise from mutations of genes, drivers that promote a tumor's growth. Analyses of driver events provide insights into cancer cell history and may lead to a better understanding of oncogenesis. We reviewed 27 metastatic research studies, including pan-cancer studies, individual cancer studies, and phylogenetic analyses, and summarized our current knowledge of metastatic drivers. All of the analyzed studies had a high level of consistency of driver mutations between primary tumors and metastasis, indicating that most drivers appear early in cancer progression and are maintained in metastatic cells. Additionally, we reviewed data from around 50,000 metastatic cancer patients and compiled a list of genes altered in metastatic lesions. We performed Gene Ontology analysis and confirmed that the most significantly enriched processes in metastatic lesions were the epigenetic regulation of gene expression, signal transduction, cell cycle, programmed cell death, DNA damage, hypoxia and EMT. In this review, we explore the most recent discoveries regarding genetic factors in the advancement of cancer, specifically those that drive metastasis.

Epigenetic regulation during meiosis and crossover

Meiosis is a distinctive type of cell division that reorganizes genetic material between generations. The initial stages of meiosis consist of several crucial steps which include double strand break, homologous chromosome pairing, break repair and crossover. Crossover frequency varies depending on the position on the chromosome, higher at euchromatin region and rare at heterochromatin, centromeres, telomeres and ribosomal DNA. Crossover positioning is dependent on various factors, especially epigenetic modifications. DNA methylation, histone post-translational modifications, histone variants and non-coding RNAs are most probably playing an important role in positioning of crossovers on a chromosomal level as well as hotspot level. DNA methylation negatively regulates crossover frequency and its effect is visible in centromeres, pericentromeres and heterochromatin regions. Pericentromeric chromatin and heterochromatin mark studies have been a centre of attraction in meiosis. Crossover hotspots are associated with euchromatin regions having specific chromatin modifications such as H3K4me3, H2A.Z. and H3 acetylation. This review will provide the current understanding of the epigenetic role in plants during meiotic recombination, chromosome synapsis, double strand break and hotspots with special attention to euchromatin and heterochromatin marks. Further, the role of epigenetic modifications in regulating meiosis and crossover in other organisms is also discussed.

Lysine succinylation, the metabolic bridge between cancer and immunity

Lysine succinylation is a naturally occurring post-translational modification (PTM) that regulates the stability and function of proteins. It can be regulated by enzymes such as SIRT5 and SIRT7. Recently, the effect and significance of lysine succinylation in cancer and its implication in immunity have been extensively explored. Lysine succinylation is involved in the malignant phenotype of cancer cells. Abnormal regulation of lysine succinylation occurs in different cancers, and inhibitors targeting lysine succinylation regulatory enzymes can be used as potential anti-cancer strategies. Therefore, this review focused on the target protein lysine succinylation and its functions in cancer and immunity, in order to provide a reference for finding more potential clinical cancer targets in the future.

GAS41 promotes H2A.Z deposition through recognition of the N terminus of histone H3 by the YEATS domain

Glioma amplified sequence 41 (GAS41), which has the Yaf9, ENL, AF9, Taf14, and Sas5 (YEATS) domain that recognizes lysine acetylation (Kac), regulates gene expression as a subunit of the SRCAP (SNF2-related CREBBP activator protein) complex that deposits histone H2A.Z at promoters in eukaryotes. The YEATS domains of the proteins AF9 and ENL recognize Kac by hydrogen bonding the aromatic cage to arginine situated just before K9ac or K27ac in the N-terminal tail of histone H3. Curiously, the YEATS domain of GAS41 binds most preferentially to the sequence that contains K14ac of H3 (H3K14ac) but lacks the corresponding arginine. Here, we biochemically and structurally elucidated the molecular mechanism by which GAS41 recognizes H3K14ac. First, stable binding of the GAS41 YEATS domain to H3K14ac required the N terminus of H3 (H3NT). Second, we revealed a pocket in the GAS41 YEATS domain responsible for the H3NT binding by crystallographic and NMR analyses. This pocket is away from the aromatic cage that recognizes Kac and is unique to GAS41 among the YEATS family. Finally, we showed that E109 of GAS41, a residue essential for the formation of the H3NT-binding pocket, was crucial for chromatin occupancy of H2A.Z and GAS41 at H2A.Z-enriched promoter regions. These data suggest that binding of GAS41 to H3NT via its YEATS domain is essential for its intracellular function.

Molecular characterization and modulated expression of histone acetyltransferases during cold response of the tick Dermacentor silvarum (Acari: Ixodidae)

BACKGROUND

Histone acetylation is involved in the regulation of stress responses in multiple organisms. Dermacentor silvarum is an important vector tick species widely distributed in China, and low temperature is a crucial factor restricting the development of its population. However, knowledge of the histone acetyltransferases and epigenetic mechanisms underlying cold-stress responses in this tick species is limited.

METHODS

Histone acetyltransferase genes were characterized in D. silvarum, and their relative expressions were determined using qPCR during cold stress. The association and modulation of histone acetyltransferase genes were further explored using RNA interference, and both the H3K9 acetylation level and relative expression of KAT5 protein were evaluated using western blotting.

RESULTS

Three histone acetyltransferase genes were identified and named as DsCREBBP, DsKAT6B, and DsKAT5. Bioinformatics analysis showed that they were unstable hydrophilic proteins, characterized by the conserved structures of CBP (ZnF_TAZ), PHA03247 super family, Creb_binding, and MYST(PLN00104) super family. Fluorescence quantitative PCR showed that the expression of DsCREBBP, DsKAT6B, and DsKAT5 increased after 3 days of cold treatment, with subsequent gradual decreases, and was lowest on day 9. Western blotting showed that both the H3K9 acetylation level and relative expression of KAT5 in D. silvarum increased after treatment at - 4, 4, and 8 °C for 3 and 6 days, whereas they decreased significantly after a 9-day treatment. RNA interference induced significant gene silencing, and the mortality rate of D. silvarum significantly increased at the respective semi-lethal temperatures.

CONCLUSION

These results imply that histone acetyltransferases play an important role in tick adaptation to low temperatures and lay a foundation for further understanding of the epigenetic regulation of histone acetylation in cold-stressed ticks. Further research is needed to elucidate the mechanisms underlying histone acetylation during cold stress in ticks.

Direct and cost-effective method for histone isolation from cultured mammalian cells

Histones are an essential part of nucleosomes that regulate chromatin structure and function. Histone exchanges and modifications represent a scaffold for DNA transcription, repair, and replication. Studying histones and histone code is an important and fast-developing branch of epigenetic science. Here we propose a fast, efficient, and versatile assay for nucleosomal histone isolation from mammalian cells, without the use of acids or high salt solutions which are common for other histone isolation techniques. All components used in the protocol are common and inexpensive laboratory chemicals. The protocol has been evaluated on six commonly used cell lines and two animal tissue samples. The mild extraction conditions preserve delicate histone epigenetic changes, allowing its downstream analyses. We have demonstrated the assays' successful application during changes in the transcriptional activity of histone genes, cell cycle transitions, and DNA-damaging conditions. Histone fractions, obtained by the protocol, can be used for further applications, such as electrophoresis, immunoblot, and mass spectrometry. Therefore, the new proposed nucleosomal histone isolation method is sensitive, specific, and suitable for downstream applications of various kinds.

Synthesis of ubiquitinated proteins for biochemical and functional analysis

Ubiquitination plays a crucial role in controlling various biological processes such as translation, DNA repair and immune response. Protein degradation for example, is one of the main processes which is controlled by the ubiquitin system and has significant implications on human health. In order to investigate these processes and the roles played by different ubiquitination patterns on biological systems, homogeneously ubiquitinated proteins are needed. Notably, these conjugates that are made enzymatically in cells cannot be easily obtained in large amounts and high homogeneity by employing such strategies. Therefore, chemical and semisynthetic approaches have emerged to prepare different ubiquitinated proteins. In this review, we will present the key synthetic strategies and their applications for the preparation of various ubiquitinated proteins. Furthermore, the use of these precious conjugates in different biochemical and functional studies will be highlighted.

Context-defined cancer co-dependency mapping identifies a functional interplay between PRC2 and MLL-MEN1 complex in lymphoma

Interplay between chromatin-associated complexes and modifications critically contribute to the partitioning of epigenome into stable and functionally distinct domains. Yet there is a lack of systematic identification of chromatin crosstalk mechanisms, limiting our understanding of the dynamic transition between chromatin states during development and disease. Here we perform co-dependency mapping of genes using CRISPR-Cas9-mediated fitness screens in pan-cancer cell lines to quantify gene-gene functional relationships. We identify 145 co-dependency modules and further define the molecular context underlying the essentiality of these modules by incorporating mutational, epigenome, gene expression and drug sensitivity profiles of cell lines. These analyses assign new protein complex composition and function, and predict new functional interactions, including an unexpected co-dependency between two transcriptionally counteracting chromatin complexes - polycomb repressive complex 2 (PRC2) and MLL-MEN1 complex. We show that PRC2-mediated H3K27 tri-methylation regulates the genome-wide distribution of MLL1 and MEN1. In lymphoma cells with EZH2 gain-of-function mutations, the re-localization of MLL-MEN1 complex drives oncogenic gene expression and results in a hypersensitivity to pharmacologic inhibition of MEN1. Together, our findings provide a resource for discovery of trans-regulatory interactions as mechanisms of chromatin regulation and potential targets of synthetic lethality.

Simple and universal function of acetic acid to overcome the drought crisis

Acetic acid is a simple and universal compound found in various organisms. Recently, acetic acid was found to play an essential role in conferring tolerance to water deficit stress in plants. This novel mechanism of drought stress tolerance mediated by acetic acid via networks involving phytohormones, genes, and chromatin regulation has great potential for solving the global food crisis and preventing desertification caused by global warming. We highlight the functions of acetic acid in conferring tolerance to water deficit stress.

Exploring structural requirements of HDAC10 inhibitors through comparative machine learning approaches

Histone deacetylase (HDAC) inhibitors are in the limelight of anticancer drug development and research. HDAC10 is one of the class-IIb HDACs, responsible for cancer progression. The search for potent and effective HDAC10 selective inhibitors is going on. However, the absence of human HDAC10 crystal/NMR structure hampers the structure-based drug design of HDAC10 inhibitors. Different ligand-based modeling techniques are the only hope to speed up the inhibitor design. In this study, we applied different ligand-based modeling techniques on a diverse set of HDAC10 inhibitors (n = 484). Machine learning (ML) models were developed that could be used to screen unknown compounds as HDAC10 inhibitors from a large chemical database. Moreover, Bayesian classification and Recursive partitioning models were used to identify the structural fingerprints regulating the HDAC10 inhibitory activity. Additionally, a molecular docking study was performed to understand the binding pattern of the identified structural fingerprints towards the active site of HDAC10. Overall, the modeling insight might offer helpful information for medicinal chemists to design and develop efficient HDAC10 inhibitors.

The role of histone deacetylases in cardiac energy metabolism in heart diseases

Heart diseases are associated with substantial morbidity and mortality worldwide. The underlying mechanisms and pathological changes associated with cardiac diseases are exceptionally complex. Highly active cardiomyocytes require sufficient energy metabolism to maintain their function. Under physiological conditions, the choice of fuel is a delicate process that depends on the whole body and organs to support the normal function of heart tissues. However, disordered cardiac metabolism has been discovered to play a key role in many forms of heart diseases, including ischemic heart disease, cardiac hypertrophy, heart failure, and cardiac injury induced by diabetes or sepsis. Regulation of cardiac metabolism has recently emerged as a novel approach to treat heart diseases. However, little is known about cardiac energy metabolic regulators. Histone deacetylases (HDACs), a class of epigenetic regulatory enzymes, are involved in the pathogenesis of heart diseases, as reported in previous studies. Notably, the effects of HDACs on cardiac energy metabolism are gradually being explored. Our knowledge in this respect would facilitate the development of novel therapeutic strategies for heart diseases. The present review is based on the synthesis of our current knowledge concerning the role of HDAC regulation in cardiac energy metabolism in heart diseases. In addition, the role of HDACs in different models is discussed through the examples of myocardial ischemia, ischemia/reperfusion, cardiac hypertrophy, heart failure, diabetic cardiomyopathy, and diabetes- or sepsis-induced cardiac injury. Finally, we discuss the application of HDAC inhibitors in heart diseases and further prospects, thus providing insights into new treatment possibilities for different heart diseases.

DDM1-Mediated TE Silencing in Plants

Epigenetic modifications are indispensable for regulating gene bodies and TE silencing. DECREASE IN DNA METHYLATION 1 (DDM1) is a chromatin remodeller involved in histone modifications and DNA methylation. Apart from maintaining the epigenome, DDM1 also maintains key plant traits such as flowering time and heterosis. The role of DDM1 in epigenetic regulation is best characterised in plants, especially arabidopsis, rice, maize and tomato. The epigenetic changes induced by DDM1 establish the stable inheritance of many plant traits for at least eight generations, yet DDM1 does not methylate protein-coding genes. The DDM1 TE silencing mechanism is distinct and has evolved independently of other silencing pathways. Unlike the RNA-directed DNA Methylation (RdDM) pathway, DDM1 does not depend on siRNAs to enforce the heterochromatic state of TEs. Here, we review DDM1 TE silencing activity in the RdDM and non-RdDM contexts. The DDM1 TE silencing machinery is strongly associated with the histone linker H1 and histone H2A.W. While the linker histone H1 excludes the RdDM factors from methylating the heterochromatin, the histone H2A.W variant prevents TE mobility. The DDM1-H2A.W strategy alone silences nearly all the mobile TEs in the arabidopsis genome. Thus, the DDM1-directed TE silencing essentially preserves heterochromatic features and abolishes mobile threats to genome stability.

Disparity in the era of personalized medicine for epithelial ovarian cancer

The treatment of high-grade serous ovarian cancer and high-grade endometrioid ovarian cancer has seen significant improvements in recent years, with BRCA1/2 and homologous recombination status guiding a personalized approach which has resulted in improved patient outcomes. However, for other epithelial ovarian cancer subtypes, first-line treatment remains unchanged from the platinum-paclitaxel trials of the early 2000s. In this review, we explore novel therapeutic approaches being adopted in the treatment of clear cell, mucinous, carcinosarcoma and low-grade serous ovarian cancer and the biological rational behind them. We discuss why such disparities exist, the challenges faced in conducting dedicated trials in these rarer histologies and look towards new approaches being adopted to overcome them.

Epigenetic malleability at core promoter initiates tobacco PR-1a expression post salicylic acid treatment

BACKGROUND

Tobacco's PR-1a gene is induced by pathogen attack or exogenous application of salicylic acid (SA). Nucleosome mapping and chromatin immunoprecipitation assay were used to delineate the histone modifications on the PR-1a promoter. However, the epigenetic modifications of the inducible promoter of the PR-1a gene are not fully understood yet.

METHODS AND RESULTS

Southern approach was used to scan the promoter of PR-1a to identify presence of nucleosomes, ChIP assays were performed using anti-histones antibodies of repressive chromatin by di- methylated at H3K9 and H4K20 or active chromatin by acetylated H3K9/14 and H4K16 to find epigenetic malleability of nucleosome over core promoter in uninduced or induced state post SA treatment. Class I and II mammalian histone deacetylase (HDAC) inhibitor TSA treatment was used to enhance the expression of PR-1a by facilitating the histone acetylation post SA treatment. Here, we report correlated consequences of the epigenetic modifications correspond to disassembly of the nucleosome (spans from - 102 to + 55 bp, masks TATA and transcription initiation) and repressor complex from core promoter, eventually initiates the transcription of PR-1a gene post SA treatment. While active chromatin marks di and trimethylation of H3K4, acetylation of H3K9 and H4K16 are increased which are associated to the transcription initiation of PR-1a following SA treatment. However, in uninduced state constitutive expression of a negative regulator (SNI1) of AtPR1, suppresses AtPR1 expression by six-fold in Arabidopsis thaliana. Further, we report 50-to-1000-fold increased expression of AtPR1 in uninduced lsd1 mutant plants, up to threefold increased expression of AtPR1 in uninduced histone acetyl transferases (HATs) mutant plants, SNI1 dependent negative regulation of AtPR1, all together our results suggest that inactive state of PR-1a is indeed maintained by a repressive complex.

CONCLUSION

The study aimed to reveal the mechanism of transcription initiation of tobacco PR-1a gene in presence or absence of SA. This is the first study that reports nucleosome and repressor complex over core promoter region maintains the inactivation of gene in uninduced state, and upon induction disassembling of both initiates the downstream gene activation process.

Acylation of the Rat Brain Proteins is Affected by the Inhibition of Pyruvate Dehydrogenase in vivo

Organism adaptation to metabolic challenges requires coupling of metabolism to gene expression. In this regard, acylations of histones and metabolic proteins acquire significant interest. We hypothesize that adaptive response to inhibition of a key metabolic process, catalyzed by the acetyl-CoA-generating pyruvate dehydrogenase (PDH) complex, is mediated by changes in the protein acylations. The hypothesis is tested by intranasal administration to animals of PDH-specific inhibitors acetyl(methyl)phosphinate (AcMeP) or acetylphosphonate methyl ester (AcPMe), followed by the assessment of physiological parameters, brain protein acylation, and expression/phosphorylation of PDHA subunit. At the same dose, AcMeP, but not AcPMe, decreases acetylation and increases succinylation of the brain proteins with apparent molecular masses of 15-20 kDa. Regarding the proteins of 30-50 kDa, a strong inhibitor AcMeP affects acetylation only, while a less efficient AcPMe mostly increases succinylation. The unchanged succinylation of the 30-50 kDa proteins after the administration of AcMeP coincides with the upregulation of desuccinylase SIRT5. No significant differences between the levels of brain PDHA expression, PDHA phosphorylation, parameters of behavior or ECG are observed in the studied animal groups. The data indicate that the short-term inhibition of brain PDH affects acetylation and/or succinylation of the brain proteins, that depends on the inhibitor potency, protein molecular mass, and acylation type. The homeostatic nature of these changes is implied by the stability of physiological parameters after the PDH inhibition.

Chromatin Immunostaining of Plant Nuclei

Recent evidence has demonstrated that specific epigenetic changes are also related to plant growth and development. Immunostaining enables the detection and characterization of chromatin modification, e.g., histone H4 acetylation (H4K5ac), histone H3 methylation (H3K4me2 and H3K9me2), and DNA methylation (5mC) with unique and specific patterns in plant tissues. Here we describe experimental procedures to determine the histone H3 methylation (H3K4me2 and H3K9me2) patterns in 3D-chromatin in whole roots tissue and 2D-chromatin in single nuclei in rice. To analyze both iron and salinity treatments, we show how to test for changes to the epigenetic chromatin landscape using heterochromatin (H3K9me2) and euchromatin (H3K4me) markers for chromatin immunostaining, especially in the proximal meristem region. To elucidate the epigenetic impact of environmental stress and external plant growth regulators, we demonstrate how to apply a combination of salinity, auxin, and abscisic acid treatments. The results of these experiments provide insights into the epigenetic landscape during rice root growth and development.

Dynamic structures of intrinsically disordered proteins related to the general transcription factor TFIIH, nucleosomes, and histone chaperones

Advances in structural analysis by cryogenic electron microscopy (cryo-EM) and X-ray crystallography have revealed the tertiary structures of various chromatin-related proteins, including transcription factors, RNA polymerases, nucleosomes, and histone chaperones; however, the dynamic structures of intrinsically disordered regions (IDRs) in these proteins remain elusive. Recent studies using nuclear magnetic resonance (NMR), together with molecular dynamics (MD) simulations, are beginning to reveal dynamic structures of the general transcription factor TFIIH complexed with target proteins including the general transcription factor TFIIE, the tumor suppressor p53, the cell cycle protein DP1, the DNA repair factors XPC and UVSSA, and three RNA polymerases, in addition to the dynamics of histone tails in nucleosomes and histone chaperones. In complexes of TFIIH, the PH domain of the p62 subunit binds to an acidic string formed by the IDR in TFIIE, p53, XPC, UVSSA, DP1, and the RPB6 subunit of three RNA polymerases by a common interaction mode, namely extended string-like binding of the IDR on the positively charged surface of the PH domain. In the nucleosome, the dynamic conformations of the N-tails of histones H2A and H2B are correlated, while the dynamic conformations of the N-tails of H3 and H4 form a histone tail network dependent on their modifications and linker DNA. The acidic IDRs of the histone chaperones of FACT and NAP1 play important roles in regulating the accessibility to histone proteins in the nucleosome.

H2B Lys34 Ubiquitination Induces Nucleosome Distortion to Stimulate Dot1L Activity

Ubiquitination-dependent histone crosstalk plays critical roles in chromatin-associated processes and is highly associated with human diseases. Mechanism studies of the crosstalk have been of the central focus. Here our study on the crosstalk between H2BK34ub and Dot1L-catalyzed H3K79me suggests a novel mechanism of ubiquitination-induced nucleosome distortion to stimulate the activity of an enzyme. We determined the cryo-electron microscopy structures of Dot1L-H2BK34ub nucleosome complex and the H2BK34ub nucleosome alone. The structures reveal that H2BK34ub induces an almost identical orientation and binding pattern of Dot1L on nucleosome as H2BK120ub, which positions Dot1L for the productive conformation through direct ubiquitin-enzyme contacts. However, H2BK34-anchored ubiquitin does not directly interact with Dot1L as occurs in the case of H2BK120ub, but rather induces DNA and histone distortion around the modified site. Our findings establish the structural framework for understanding the H2BK34ub-H3K79me trans-crosstalk and highlight the diversity of mechanisms for histone ubiquitination to activate chromatin-modifying enzymes.

Oncohistones: Exposing the nuances and vulnerabilities of epigenetic regulation

Work over the last decade has uncovered a new layer of epigenetic dysregulation. It is now appreciated that somatic missense mutations in histones, the packaging agents of genomic DNA, are often associated with human pathologies, especially cancer. Although some of these "oncohistone" mutations are thought to be key drivers of cancer, the impacts of the majority of them on disease onset and progression remain to be elucidated. Here, we survey this rapidly expanding research field with particular emphasis on how histone mutants, even at low dosage, can corrupt chromatin states. This work is unveiling the remarkable intricacies of epigenetic control mechanisms. Throughout, we highlight how studies of oncohistones have leveraged, and in some cases fueled, the advances in our ability to manipulate and interrogate chromatin at the molecular level.

Chromatin-Associated Molecular Patterns (CAMPs) in sepsis

Several molecular patterns have been identified that recognize pattern recognition receptors. Pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) are commonly used terminologies to classify molecules originating from pathogen and endogenous molecules, respectively, to heighten the immune response in sepsis. Herein, we focus on a subgroup of endogenous molecules that may be detected as foreign and similarly trigger immune signaling pathways. These chromatin-associated molecules, i.e., chromatin containing nuclear DNA and histones, extracellular RNA, mitochondrial DNA, telomeric repeat-containing RNA, DNA- or RNA-binding proteins, and extracellular traps, may be newly classified as chromatin-associated molecular patterns (CAMPs). Herein, we review the release of CAMPs from cells, their mechanism of action and downstream immune signaling pathways, and targeted therapeutic approaches to mitigate inflammation and tissue injury in inflammation and sepsis.

N-Terminal Tails of Histones H2A and H2B Differentially Affect Transcription by RNA Polymerase II In Vitro

Histone N-terminal tails and their post-translational modifications affect various biological processes, often in a context-specific manner; the underlying mechanisms are poorly studied. Here, the role of individual N-terminal tails of histones H2A/H2B during transcription through chromatin was analyzed in vitro. spFRET data suggest that the tail of histone H2B (but not of histone H2A) affects nucleosome stability. Accordingly, deletion of the H2B tail (amino acids 1–31, but not 1–26) causes a partial relief of the nucleosomal barrier to transcribing RNA polymerase II (Pol II), likely facilitating uncoiling of DNA from the histone octamer during transcription. Taken together, the data suggest that residues 27–31 of histone H2B stabilize DNA–histone interactions at the DNA region localized ~25 bp in the nucleosome and thus interfere with Pol II progression through the region localized 11–15 bp in the nucleosome. This function of histone H2B requires the presence of the histone H2A N-tail that mediates formation of nucleosome–nucleosome dimers; however, nucleosome dimerization per se plays only a minimal role during transcription. Histone chaperone FACT facilitates transcription through all analyzed nucleosome variants, suggesting that H2A/H2B tails minimally interact with FACT during transcription; therefore, an alternative FACT-interacting domain(s) is likely involved in this process.

Consensus clustering for Bayesian mixture models

BACKGROUND

Cluster analysis is an integral part of precision medicine and systems biology, used to define groups of patients or biomolecules. Consensus clustering is an ensemble approach that is widely used in these areas, which combines the output from multiple runs of a non-deterministic clustering algorithm. Here we consider the application of consensus clustering to a broad class of heuristic clustering algorithms that can be derived from Bayesian mixture models (and extensions thereof) by adopting an early stopping criterion when performing sampling-based inference for these models. While the resulting approach is non-Bayesian, it inherits the usual benefits of consensus clustering, particularly in terms of computational scalability and providing assessments of clustering stability/robustness.

RESULTS

In simulation studies, we show that our approach can successfully uncover the target clustering structure, while also exploring different plausible clusterings of the data. We show that, when a parallel computation environment is available, our approach offers significant reductions in runtime compared to performing sampling-based Bayesian inference for the underlying model, while retaining many of the practical benefits of the Bayesian approach, such as exploring different numbers of clusters. We propose a heuristic to decide upon ensemble size and the early stopping criterion, and then apply consensus clustering to a clustering algorithm derived from a Bayesian integrative clustering method. We use the resulting approach to perform an integrative analysis of three 'omics datasets for budding yeast and find clusters of co-expressed genes with shared regulatory proteins. We validate these clusters using data external to the analysis.

CONCLUSTIONS

Our approach can be used as a wrapper for essentially any existing sampling-based Bayesian clustering implementation, and enables meaningful clustering analyses to be performed using such implementations, even when computational Bayesian inference is not feasible, e.g. due to poor exploration of the target density (often as a result of increasing numbers of features) or a limited computational budget that does not along sufficient samples to drawn from a single chain. This enables researchers to straightforwardly extend the applicability of existing software to much larger datasets, including implementations of sophisticated models such as those that jointly model multiple datasets.

Post-Translational Modifications of Histones Are Versatile Regulators of Fungal Development and Secondary Metabolism

Chromatin structure is a major regulator of DNA-associated processes, such as transcription, DNA repair, and replication. Histone post-translational modifications, or PTMs, play a key role on chromatin dynamics. PTMs are involved in a wide range of biological processes in eukaryotes, including fungal species. Their deposition/removal and their underlying functions have been extensively investigated in yeasts but much less in other fungi. Nonetheless, the major role of histone PTMs in regulating primary and secondary metabolisms of filamentous fungi, including human and plant pathogens, has been pinpointed. In this review, an overview of major identified PTMs and their respective functions in fungi is provided, with a focus on filamentous fungi when knowledge is available. To date, most of these studies investigated histone acetylations and methylations, but the development of new methodologies and technologies increasingly allows the wider exploration of other PTMs, such as phosphorylation, ubiquitylation, sumoylation, and acylation. Considering the increasing number of known PTMs and the full range of their possible interactions, investigations of the subsequent Histone Code, i.e., the biological consequence of the combinatorial language of all histone PTMs, from a functional point of view, are exponentially complex. Better knowledge about histone PTMs would make it possible to efficiently fight plant or human contamination, avoid the production of toxic secondary metabolites, or optimize the industrial biosynthesis of certain beneficial compounds.

Characteristic H3 N-tail dynamics in the nucleosome core particle, nucleosome, and chromatosome

The nucleosome core particle (NCP) comprises a histone octamer, wrapped around by ∼146-bp DNA, while the nucleosome additionally contains linker DNA. We previously showed that, in the nucleosome, H4 N-tail acetylation enhances H3 N-tail acetylation by altering their mutual dynamics. Here, we have evaluated the roles of linker DNA and/or linker histone on H3 N-tail dynamics and acetylation by using the NCP and the chromatosome (i.e., linker histone H1.4-bound nucleosome). In contrast to the nucleosome, H3 N-tail acetylation and dynamics are greatly suppressed in the NCP regardless of H4 N-tail acetylation because the H3 N-tail is strongly bound between two DNA gyres. In the chromatosome, the asymmetric H3 N-tail adopts two conformations: one contacts two DNA gyres, as in the NCP; and one contacts linker DNA, as in the nucleosome. However, the rate of H3 N-tail acetylation is similar in the chromatosome and nucleosome. Thus, linker DNA and linker histone both regulate H3-tail dynamics and acetylation.

Advances in proteome-wide analysis of plant lysine acetylation

Lysine acetylation (LysAc) is a conserved and important post-translational modification (PTM) that plays a key role in plant physiological and metabolic processes. Based on advances in Lys-acetylated protein immunoenrichment and mass-spectrometric technology, LysAc proteomics studies have been performed in many species. Such studies have made substantial contributions to our understanding of plant LysAc, revealing that Lys-acetylated histones and nonhistones are involved in a broad spectrum of plant cellular processes. Here, we present an extensive overview of recent research on plant Lys-acetylproteomes. We provide in-depth insights into the characteristics of plant LysAc modifications and the mechanisms by which LysAc participates in cellular processes and regulates metabolism and physiology during plant growth and development. First, we summarize the characteristics of LysAc, including the properties of Lys-acetylated sites, the motifs that flank Lys-acetylated lysines, and the dynamic alterations in LysAc among different tissues and developmental stages. We also outline a map of Lys-acetylated proteins in the Calvin-Benson cycle and central carbon metabolism-related pathways. We then introduce some examples of the regulation of plant growth, development, and biotic and abiotic stress responses by LysAc. We discuss the interaction between LysAc and Nα-terminal acetylation and the crosstalk between LysAc and other PTMs, including phosphorylation and succinylation. Finally, we propose recommendations for future studies in the field. We conclude that LysAc of proteins plays an important role in the regulation of the plant life cycle.

Unconventional metabolites in chromatin regulation

Chromatin, the complex of DNA and histone proteins, serves as a main integrator of cellular signals. Increasing evidence links cellular functional to chromatin state. Indeed, different metabolites are emerging as modulators of chromatin function and structure. Alterations in chromatin state are decisive for regulating all aspects of genome function and ultimately have the potential to produce phenotypic changes. Several metabolites such as acetyl-CoA, S-adenosylmethionine (SAM) or adenosine triphosphate (ATP) have now been well characterized as main substrates or cofactors of chromatin-modifying enzymes. However, there are other metabolites that can directly interact with chromatin influencing its state or that modulate the properties of chromatin regulatory factors. Also, there is a growing list of atypical enzymatic and nonenzymatic chromatin modifications that originate from different cellular pathways that have not been in the limelight of chromatin research. Here, we summarize different properties and functions of uncommon regulatory molecules originating from intermediate metabolism of lipids, carbohydrates and amino acids. Based on the various modes of action on chromatin and the plethora of putative, so far not described chromatin-regulating metabolites, we propose that there are more links between cellular functional state and chromatin regulation to be discovered. We hypothesize that these connections could provide interesting starting points for interfering with cellular epigenetic states at a molecular level.

Structural Analysis of SMYD3 Lysine Methyltransferase for the Development of Competitive and Specific Enzyme Inhibitors

Lysine methylation is among the key posttranslational modifications to histones that contribute to epigenetic regulation. SMYD3 is a lysine methyltransferase that is essential for the proliferation of a range of tumorigenic cells. The findings that SMYD3 is significantly upregulated in most colorectal carcinomas, hepatocellular carcinomas, and breast cell carcinomas support a model in which its aberrant expression modifies established patterns of gene expression, ultimately driving unrestrained proliferation. Herein, we dissect the unique structural features of SMYD3 relative to other SET enzymes, with an emphasis on the implications for selective design of therapeutics for the clinical management of cancer. Further, we illustrate the ability of inhibitors targeting the SET domain of SMYD3 to reduce the viability of colorectal and lung carcinoma cells.

Molecular characterization of substrate-induced ubiquitin transfer by UBR7-PHD finger, a newly identified histone H2BK120 ubiquitin ligase

Monoubiquitination of histone H2B at lysine 120 plays a vital role in active transcription and DNA damage response pathways. Ubiquitin protein ligase E3 component N-recognin 7 (UBR7) has been recently identified as an H2BK120 monoubiquitin ligase. However, the molecular details of its ubiquitin transfer mechanism are not well understood. Here, we report that the plant homeodomain (PHD) finger of UBR7 is essential for its association with E2 UbcH6 and consequent ubiquitin transfer to its substrate histone H2B. We also identified the critical region of UbcH6 involved in this function and shown that the residues stretching from 114 to 125 of histone H2B C-terminal tail are sufficient for UBR7/UbcH6-mediated ubiquitin transfer. We also employed antibody-independent mass spectrometry to confirm UBR7-mediated ubiquitination of the H2B C-terminal tail. We demonstrated that the PHD finger of UBR7 forms a dimer and this dimerization is essential for ubiquitination of histone H2B. We mapped the critical residues involved in the dimerization and mutation of these residues that abrogate E3 ligase activity and are associated with cancer. Furthermore, we compared the mode of ubiquitin discharge from UbcH6 mediated by UBR7 and RING finger protein 20 (RNF20) through a thioester hydrolysis assay. Interestingly, binding of substrate H2B to UBR7 induces a conformational change in the PHD finger, which triggers ubiquitin transfer from UbcH6. However, the RNF20 RING finger alone is sufficient to promote the release of ubiquitin from UbcH6. Overall, the mechanism of ubiquitin transfer by the newly identified E3 ubiquitin ligase UBR7 is markedly different from that of RNF20.

Actin R256 Mono-methylation Is a Conserved Post-translational Modification Involved in Transcription

Nuclear actin has been elusive due to the lack of knowledge about molecular mechanisms. From actin-containing chromatin remodeling complexes, we discovered an arginine mono-methylation mark on an evolutionarily conserved R256 residue of actin (R256me1). Actin R256 mutations in yeast affect nuclear functions and cause diseases in human. Interestingly, we show that an antibody specific for actin R256me1 preferentially stains nuclear actin over cytoplasmic actin in yeast, mouse, and human cells. We also show that actin R256me1 is regulated by protein arginine methyl transferase-5 (PRMT5) in HEK293 cells. A genome-wide survey of actin R256me1 mark provides a landscape for nuclear actin correlated with transcription. Further, gene expression and protein interaction studies uncover extensive correlations between actin R256me1 and active transcription. The discovery of actin R256me1 mark suggests a fundamental mechanism to distinguish nuclear actin from cytoplasmic actin through post-translational modification (PTM) and potentially implicates an actin PTM mark in transcription and human diseases.

Nuclear actin and actin PTMs are poorly understood. Kumar et al. discover a system of actin PTMs similar to histone PTMs, including a conserved mark on nuclear actin (R256me1) with potential implications for transcription and human diseases.

Investigating crosstalk between H3K27 acetylation and H3K4 trimethylation in CRISPR/dCas-based epigenome editing and gene activation

Epigenome editing methods enable the precise manipulation of epigenetic modifications, such as histone posttranscriptional modifications (PTMs), for uncovering their biological functions. While histone PTMs have been correlated with certain gene expression status, the causalities remain elusive. Histone H3 Lysine 27 acetylation (H3K27ac) and histone H3 Lysine 4 trimethylation (H3K4me3) are both associated with active genes, and located at active promoters and enhancers or around transcriptional start sites (TSSs). Although crosstalk between histone lysine acetylation and H3K4me3 has been reported, relationships between specific epigenetic marks during transcriptional activation remain largely unclear. Here, using clustered regularly interspaced short palindromic repeats (CRISPR)/dCas-based epigenome editing methods, we discovered that the ectopic introduction of H3K27ac in the promoter region lead to H3K4me3 enrichment around TSS and transcriptional activation, while H3K4me3 installation at the promoter cannot induce H3K27ac increase and failed to activate gene expression. Blocking the reading of H3K27ac by BRD proteins using inhibitor JQ1 abolished H3K27ac-induced H3K4me3 installation and downstream gene activation. Furthermore, we uncovered that BRD2, not BRD4, mediated H3K4me3 installation and gene activation upon H3K27ac writing. Our studies revealed the relationships between H3K27ac and H3K4me3 in gene activation process and demonstrated the application of CRISPR/dCas-based epigenome editing methods in elucidating the crosstalk between epigenetic mechanisms.

Structure, Activity and Function of the NSD3 Protein Lysine Methyltransferase

NSD3 is one of six H3K36-specific lysine methyltransferases in metazoans, and the methylation of H3K36 is associated with active transcription. NSD3 is a member of the nuclear receptor-binding SET domain (NSD) family of histone methyltransferases together with NSD1 and NSD2, which generate mono- and dimethylated lysine on histone H3. NSD3 is mutated and hyperactive in some human cancers, but the biochemical mechanisms underlying such dysregulation are barely understood. In this review, the current knowledge of NSD3 is systematically reviewed. Finally, the molecular and functional characteristics of NSD3 in different tumor types according to the current research are summarized.

The Updating of Biological Functions of Methyltransferase SETDB1 and Its Relevance in Lung Cancer and Mesothelioma

SET domain bifurcated 1 (SETDB1) is a histone H3 lysine 9 (H3K9) methyltransferase that exerts important effects on epigenetic gene regulation. SETDB1 complexes (SETDB1-KRAB-KAP1, SETDB1-DNMT3A, SETDB1-PML, SETDB1-ATF7IP-MBD1) play crucial roles in the processes of histone methylation, transcriptional suppression and chromatin remodelling. Therefore, aberrant trimethylation at H3K9 due to amplification, mutation or deletion of SETDB1 may lead to transcriptional repression of various tumour-suppressing genes and other related genes in cancer cells. Lung cancer is the most common type of cancer worldwide in which SETDB1 amplification and H3K9 hypermethylation have been indicated as potential tumourigenesis markers. In contrast, frequent inactivation mutations of SETDB1 have been revealed in mesothelioma, an asbestos-associated, locally aggressive, highly lethal, and notoriously chemotherapy-resistant cancer. Above all, the different statuses of SETDB1 indicate that it may have different biological functions and be a potential diagnostic biomarker and therapeutic target in lung cancer and mesothelioma.

Roles of the tumor suppressor inhibitor of growth family member 4 (ING4) in cancer

Inhibitor of growth family member 4 (ING4) is best known as a tumor suppressor that is frequently downregulated, deleted, or mutated in many cancers. ING4 regulates a broad array of tumor-related processes including proliferation, apoptosis, migration, autophagy, invasion, angiogenesis, DNA repair and chromatin remodeling. ING4 alters local chromatin structure by functioning as an epigenetic reader of H3K4 trimethylation histone marks (H3K4Me3) and regulating gene transcription through directing histone acetyltransferase (HAT) and histone deacetylase (HDAC) protein complexes. ING4 may serve as a useful prognostic biomarker for many cancer types and help guide treatment decisions. This review provides an overview of ING4's central functions in gene expression and summarizes current literature on the role of ING4 in cancer and its possible use in therapy.

Histone deacetylase 10, a potential epigenetic target for therapy

Histone deacetylase (HDAC) 10, a class II family, has been implicated in various tumors and non-tumor diseases, which makes the discovery of biological functions and novel inhibitors a fundamental endeavor. In cancers, HDAC10 plays crucial roles in regulating various cellular processes through its epigenetic functions or targeting some decisive molecular or signaling pathways. It also has potential clinical utility for targeting tumors and non-tumor diseases, such as renal cell carcinoma, prostate cancer, immunoglobulin A nephropathy (IgAN), intracerebral hemorrhage, human immunodeficiency virus (HIV) infection and schizophrenia. To date, relatively few studies have investigated HDAC10-specific inhibitors. Therefore, it is important to study the biological functions of HDAC10 for the future development of specific HDAC10 inhibitors. In this review, we analyzed the biological functions, mechanisms and inhibitors of HDAC10, which makes HDAC10 an appealing therapeutic target.

Methylation as a critical epigenetic process during tumor progressions among Iranian population: an overview

Cancer is one of the main health challenges and leading causes of deaths in the world. Various environmental and genetic risk factors are associated with tumorigenesis. Epigenetic deregulations are also important risk factors during tumor progression which are reversible transcriptional alterations without any genomic changes. Various mechanisms are involved in epigenetic regulations such as DNA methylation, chromatin modifications, and noncoding RNAs. Cancer incidence and mortality have a growing trend during last decades among Iranian population which are significantly related to the late diagnosis. Therefore, it is required to prepare efficient molecular diagnostic panels for the early detection of cancer in this population. Promoter hyper methylation is frequently observed as an inhibitory molecular mechanism in various genes associated with DNA repair, cell cycle regulation, and apoptosis during tumor progression. Since aberrant promoter methylations have critical roles in early stages of neoplastic transformations, in present review we have summarized all of the aberrant methylations which have been reported during tumor progression among Iranian cancer patients. Aberrant promoter methylations are targetable and prepare novel therapeutic options for the personalized medicine in cancer patients. This review paves the way to introduce a non-invasive methylation specific panel of diagnostic markers for the early detection of cancer among Iranians.

The role of nuclear Ca2+ in maintaining neuronal homeostasis and brain health

Nuclear Ca2+ has emerged as one of the most potent mediators of the dialogue between neuronal synapses and the nucleus that regulates heterochromatin states, transcription factor activity, nuclear morphology and neuronal gene expression induced by synaptic activity. Recent studies underline the importance of nuclear Ca2+ signaling in long-lasting, activity-induced adaptation and maintenance of proper brain function. Diverse forms of neuroadaptation require transient nuclear Ca2+ signaling and cyclic AMP-responsive element-binding protein (CREB1, referred to here as CREB) as its prime target, which works as a tunable switch to drive and modulate specific gene expression profiles associated with memory, pain, addiction and neuroprotection. Furthermore, a reduction of nuclear Ca2+ levels has been shown to be neurotoxic and a causal factor driving the progression of neurodegenerative disorders, as well as affecting neuronal autophagy. Because of its central role in the brain, deficits in nuclear Ca2+ signaling may underlie a continuous loss of neuroprotection in the aging brain, contributing to the pathophysiology of Alzheimer's disease. In this Review, we discuss the principles of the 'nuclear calcium hypothesis' in the context of human brain function and its role in controlling diverse forms of neuroadaptation and neuroprotection. Furthermore, we present the most relevant and promising perspectives for future studies.

H3K4me2 ChIP-Seq reveals the epigenetic landscape during mushroom formation and novel developmental regulators of Schizophyllum commune

Mushroom formation represents the most complex multicellular development in fungi. In the model mushroom Schizophyllum commune, comparative genomics and transcriptomics have previously resulted in a regulatory model of mushroom development. However, little is known about the role of epigenetic regulation. We used chromatin immunoprecipitation sequencing (ChIP-Seq) to determine the distribution of dimethylation of lysine 4 on histone H3 (H3K4me2), a mark for transcriptionally active genes, during monokaryotic and dikaryotic development. We identified a total of 6032 and 5889 sites during monokaryotic and dikaryotic development, respectively. The sites were strongly enriched near translation initiation sites of genes. Although the overall epigenetic landscape was similar between both conditions, we identified 837 sites of differential enrichment during monokaryotic or dikaryotic development, associated with 965 genes. Six transcription factor genes were enriched in H3K4me2 during dikaryotic development, indicating that these are epigenetically regulated during development. Deletion of two of these genes (fst1 and zfc7) resulted in arrested development of fruiting bodies, resulting in immature mushrooms. Together these results indicate that H3K4me2 ChIP-Seq is a powerful new tool to map the restructuring of the epigenetic landscape during mushroom development. Moreover, it can be used to identify novel developmental regulators.

The Biological Significance of Targeting Acetylation-Mediated Gene Regulation for Designing New Mechanistic Tools and Potential Therapeutics

The molecular interplay between nucleosomal packaging and the chromatin landscape regulates the transcriptional programming and biological outcomes of downstream genes. An array of epigenetic modifications plays a pivotal role in shaping the chromatin architecture, which controls DNA access to the transcriptional machinery. Acetylation of the amino acid lysine is a widespread epigenetic modification that serves as a marker for gene activation, which intertwines the maintenance of cellular homeostasis and the regulation of signaling during stress. The biochemical horizon of acetylation ranges from orchestrating the stability and cellular localization of proteins that engage in the cell cycle to DNA repair and metabolism. Furthermore, lysine acetyltransferases (KATs) modulate the functions of transcription factors that govern cellular response to microbial infections, genotoxic stress, and inflammation. Due to their central role in many biological processes, mutations in KATs cause developmental and intellectual challenges and metabolic disorders. Despite the availability of tools for detecting acetylation, the mechanistic knowledge of acetylation-mediated cellular processes remains limited. This review aims to integrate molecular and structural bases of KAT functions, which would help design highly selective tools for understanding the biology of KATs toward developing new disease treatments.

Schistosoma mansoni Heterochromatin Protein 1 (HP1) nuclear interactome in cercariae

Schistosoma mansoni causes schistosomiasis, which affects 240 million people, and 700 million people are living at risk of infection. Epigenetic mechanisms are important for transcriptional control and are well-known conserved transcriptional co-regulators in evolution, already described in mammal, yeast, protozoa and S. mansoni, responsible for heterochromatization and gene silence mechanisms through the formation of complexes of transcriptional repression in chromatin. Previous results from another group have shown that HP1 (SmCBX) proteins form chromatin complexes with SmMDB2/3 proteins and regulate stem cells and oviposition in parasite adult worms. In addition, results from other groups have shown that cercariae are transcriptionally silent and epigenetic mechanisms are involved in the regulation of gene expression in this stage. In this work, our aim was to give insights into SmHP1 and proteins involved in transcriptional regulation in the cercariae stage. Using monoclonal anti-HP1 antibody for Western blotting, immunoprecipitation, and mass spectrometry, we preliminarily determined nuclear proteins that putatively interact with HP1 to form complexes to regulate gene expression, heterochromatin formation, and translational complexes in the cercariae stage. So far, our data is to give some insights into nuclear interactors in S. mansoni cercariae. SIGNIFICANCE: The significance of this original paper is the evidence for Heterochromatin Protein (HP1), interaction with nuclear proteins in the cercariae stage. Schistosoma mansoni cercariae are the infective stage of the human beings in endemic areas of schistosomiasis, a neglected disease, most prevalent in Brazil and Africa. While cercariae are waiting for a host, it does not feed, gene expression is silent and protein synthesis is stopped. These biochemical mechanisms are recovered when cercariae find a human host, but all proteins and mechanisms are not still elucidated. Until now, literature shows that these phenomena are regulated by epigenetics mechanisms, dependent of histone posttranslational modifications. But we have few pieces of evidence about the other proteins that participates in these processes and which are the co-regulators of expression.

Induction of HOX Genes by Hepatitis C Virus Infection via Impairment of Histone H2A Monoubiquitination

Hepatitis C virus (HCV) infection causes liver pathologies, including hepatocellular carcinoma (HCC). Homeobox (HOX) gene products regulate embryonic development and are associated with tumorigenesis, although the regulation of HOX genes by HCV infection has not been clarified in detail. We examined the effect of HCV infection on HOX gene expression. In this study, HCV infection induced more than half of the HOX genes and reduced the level of histone H2A monoubiquitination on lysine 119 (K119) (H2Aub), which represses HOX gene promoter activity. HCV infection also promoted proteasome-dependent degradation of RNF2, which is an E3 ligase mediating H2A monoubiquitination as a component of polycomb repressive complex 1. Since full-genomic replicon cells but not subgenomic replicon cells exhibited reduced RNF2 and H2Aub levels and induction of HOX genes, we focused on the core protein. Expression of the core protein reduced the amounts of RNF2 and H2Aub and induced HOX genes. Treatment with LY-411575, which can reduce HCV core protein expression via signal peptide peptidase (SPP) inhibition without affecting other viral proteins, dose-dependently restored the amounts of RNF2 and H2Aub in HCV-infected cells and impaired the induction of HOX genes and production of viral particles but not viral replication. The chromatin immunoprecipitation assay results also indicated infection- and proteasome-dependent reductions in H2Aub located in HOX gene promoters. These results suggest that HCV infection or core protein induces HOX genes by impairing histone H2A monoubiquitination via a reduction in the RNF2 level.IMPORTANCE Recently sustained virologic response can be achieved by direct-acting antiviral (DAA) therapy in most hepatitis C patients. Unfortunately, DAA therapy does not completely eliminate a risk of hepatocellular carcinoma (HCC). Several epigenetic factors, including histone modifications, are well known to contribute to hepatitis C virus (HCV)-associated HCC. However, the regulation of histone modifications by HCV infection has not been clarified in detail. In this study, our data suggest that HCV infection or HCV core protein expression impairs monoubiquitination of histone H2A K119 in the homeobox (HOX) gene promoter via destabilization of RNF2 and then induces HOX genes. Several lines of evidence suggest that the expression of several HOX genes is dysregulated in certain types of tumors. These findings reveal a novel mechanism of HCV-related histone modification and may provide information about new targets for diagnosis and prevention of HCC occurrence.

The Functions of the Demethylase JMJD3 in Cancer

Cancer is a major cause of death worldwide. Epigenetic changes in response to external (diet, sports activities, etc.) and internal events are increasingly implicated in tumor initiation and progression. In this review, we focused on post-translational changes in histones and, more particularly, the tri methylation of lysine from histone 3 (H3K27me3) mark, a repressive epigenetic mark often under- or overexpressed in a wide range of cancers. Two actors regulate H3K27 methylation: Jumonji Domain-Containing Protein 3 demethylase (JMJD3) and Enhancer of zeste homolog 2 (EZH2) methyltransferase. A number of studies have highlighted the deregulation of these actors, which is why this scientific review will focus on the role of JMJD3 and, consequently, H3K27me3 in cancer development. Data on JMJD3’s involvement in cancer are classified by cancer type: nervous system, prostate, blood, colorectal, breast, lung, liver, ovarian, and gastric cancers.

Genome-Wide Histone Modifications and CTCF Enrichment Predict Gene Expression in Sheep Macrophages

Alveolar macrophages function in innate and adaptive immunity, wound healing, and homeostasis in the lungs dependent on tissue-specific gene expression under epigenetic regulation. The functional diversity of tissue resident macrophages, despite their common myeloid lineage, highlights the need to study tissue-specific regulatory elements that control gene expression. Increasing evidence supports the hypothesis that subtle genetic changes alter sheep macrophage response to important production pathogens and zoonoses, for example, viruses like small ruminant lentiviruses and bacteria like Coxiella burnetii. Annotation of transcriptional regulatory elements will aid researchers in identifying genetic mutations of immunological consequence. Here we report the first genome-wide survey of regulatory elements in any sheep immune cell, utilizing alveolar macrophages. We assayed histone modifications and CTCF enrichment by chromatin immunoprecipitation with deep sequencing (ChIP-seq) in two sheep to determine cis-regulatory DNA elements and chromatin domain boundaries that control immunity-related gene expression. Histone modifications included H3K4me3 (denoting active promoters), H3K27ac (active enhancers), H3K4me1 (primed and distal enhancers), and H3K27me3 (broad silencers). In total, we identified 248,674 reproducible regulatory elements, which allowed assignment of putative biological function in macrophages to 12% of the sheep genome. Data exceeded the FAANG and ENCODE standards of 20 million and 45 million useable fragments for narrow and broad marks, respectively. Active elements showed consensus with RNA-seq data and were predictive of gene expression in alveolar macrophages from the publicly available Sheep Gene Expression Atlas. Silencer elements were not enriched for expressed genes, but rather for repressed developmental genes. CTCF enrichment enabled identification of 11,000 chromatin domains with mean size of 258 kb. To our knowledge, this is the first report to use immunoprecipitated CTCF to determine putative topological domains in sheep immune cells. Furthermore, these data will empower phenotype-associated mutation discovery since most causal variants are within regulatory elements.

Epigenetic regulation of geminivirus pathogenesis: a case of relentless recalibration of defence responses in plants

Geminiviruses constitute one of the largest families of plant viruses and they infect many economically important crops. The proteins encoded by the single-stranded DNA genome of these viruses interact with a wide range of host proteins to cause global dysregulation of cellular processes and help establish infection in the host. Geminiviruses have evolved numerous mechanisms to exploit host epigenetic processes to ensure the replication and survival of the viral genome. Here, we review our current knowledge of diverse epigenetic processes that have been implicated in the regulation of geminivirus pathogenesis, including DNA methylation, histone post-transcriptional modification, chromatin remodelling, and nucleosome repositioning. In addition, we discuss the currently limited evidence of host epigenetic defence responses that are aimed at counteracting geminivirus infection, and the potential for exploiting these responses for the generation of resistance against geminiviruses in crop species.