The diverse functions of histone lysine methylation

Selenalysine as a Chemical Tool for Probing Histone Post-Translational Modifications

Post-translational modifications (PTMs) on histones play a crucial role in determining the structure and function of chromatin, thereby regulating the eukaryotic gene expression. Histone lysine methylation and acetylation are among the most widespread and biomedically important PTMs, with new chemical tools for their examination in high demand. Here, we report the first use of γ-selenalysine as an efficient lysine mimic for enzymatic methylation, acetylation, and deacetylation reactions catalyzed by histone lysine methyltransferases, acetyltransferases, and a deacetylase. We also show that easily accessible selenocysteine and cysteine residues can undergo chemo- and site-selective alkylation reactions to generate both unmodified and modified γ-selenalysine and related γ-thialysine residues in histone peptides. This dual-modification strategy enables the site-specific incorporation of two distinct functionalities into peptides, mimicking lysine post-translational modifications commonly found on histones. Our research presents a novel approach in which selenocysteine serves as a unique handle for the chemoselective introduction of selenalysine, along with its methylated and acetylated analogues. These tools are designed to facilitate the study of epigenetic proteins that are important for human health and disease.

Unlocking the Mysteries of Breast Cancer: The Role of Epigenetics in Diagnosis, Treatment, and Beyond

OBJECTIVES

Breast cancer is an intricate and varied disease exhibiting a range of molecular subgroups and clinical consequences. Epigenetic alterations have become essential players in the pathophysiology of breast cancer because they control gene expression without changing the DNA sequence. This review provides a comprehensive overview of epigenetics' diagnostic, prognostic, and therapeutic implications in breast cancer. This review aims to present a comprehensive study of the function of epigenetics in breast cancer, emphasizing current developments and potential avenues for future research.

METHODS

A narrative review methodology involved an extensive literature search and selection to gather relevant studies and trial data. PubMed, Embase, and Web of Science databases were searched using relevant keywords such as "epigenetics," "breast cancer," "DNA methylation," "histone modification," "noncoding RNA," and "linical trials." Relevant studies and clinical trial data were selected and synthesized to summarize the topic comprehensively.

RESULTS

The review synthesizes critical findings from current research, underscoring the pivotal role of epigenetic mechanisms in breast cancer initiation, progression, and therapeutic response. It highlights the potential of epigenetic biomarkers for diagnosis and prognosis and the promise of epigenetic-targeted therapies in breast cancer management. Furthermore, the review outlines future directions for research, emphasizing the importance of elucidating the dynamic interplay between epigenetic alterations and tumor microenvironments in shaping breast cancer phenotypes.

CONCLUSIONS

Epigenetic modifications influence breast cancer progression, diagnosis, and therapy. Emerging biomarkers and targeted treatments hold promise, but further research is essential to refine their clinical application and improve personalized cancer management strategies.

Epigenetic drugs in cancer therapy

Genetic and epigenetic modifications of DNA are involved in cancer initiation and progression. Epigenetic modifications change chromatin structure and DNA accessibility and thus affect DNA replication, DNA repair and transcription. Epigenetic modifications are reversible and include DNA methylation, histone acetylation and histone methylation. DNA methylation is catalysed by DNA methyltransferases, histone acetylation and deacetylation are catalysed by histone acetylases and deacetylases, while histone methylation is catalysed by histone methyltransferases. Epigenetic modifications are dysregulated in several cancers, making them cancer therapeutic targets. Epigenetic drugs (epi-drugs) which are inhibitors of epigenetic modifications and include DNA methyltransferase inhibitors (DNMTi), histone deacetylase inhibitors (HDACi), histone methyltransferase inhibitors (HMTi) and bromodomain and extra-terminal motif protein inhibitors (BETi), have demonstrated clinical success as anti-cancer agents. Furthermore, the combination of epi-drugs with standard chemotherapeutic agents has demonstrated promising anti-cancer effects in pre-clinical and clinical settings. In this review, we discuss the role of epi-drugs in cancer therapy and explore their current and future use in combination with other anti-cancer agents used in the clinic. We further highlight the side effects and limitations of epi-drugs. We additionally discuss novel delivery methods and novel tumour epigenetic biomarkers for the screening, diagnosis and development of personalised cancer treatments, in order to reduce off-target toxicity and improve the specificity and anti-tumour efficacy of epi-drugs.

Potent and selective SETDB1 covalent negative allosteric modulator reduces methyltransferase activity in cells

A promising drug target, SETDB1, is a dual methyl-lysine (Kme) reader and methyltransferase implicated in cancer and neurodegenerative disease progression. To help understand the role of the triple Tudor domain (3TD) of SETDB1, its Kme reader, we first identify a low micromolar potency small molecule ligand, UNC6535, which occupies simultaneously both the TD2 and TD3 reader binding sites. Further optimization leads to the discovery of UNC10013, a covalent 3TD ligand targeting Cys385 of SETDB1. UNC10013 is potent with a kinact/KI of 1.0 × 106 M-1s-1 and demonstrates proteome-wide selectivity. In cells, negative allosteric modulation of SETDB1-mediated Akt methylation occurs after treatment with UNC10013. Therefore, UNC10013 is a potent, selective, and cell-active covalent ligand for the 3TD of SETDB1, demonstrating negative allosteric modulator properties and making it a promising tool to study the biological role of SETDB1 in disease progression.

Roles and mechanisms of histone methylation in vascular aging and related diseases

The global aging trend has posed significant challenges, rendering healthcare for older adults a crucial focus in medical research. Among the numerous health concerns related to aging, vascular aging and dysfunction are important risk factors and underlying causes of age-related diseases. Histone methylation and demethylation, which are involved in gene expression and cellular senescence, are closely associated with the occurrence and development of vascular aging. Consequently, this review aimed to identify the role of histone methylation in the pathogenesis of vascular aging and its potential for treating age-related vascular diseases and provided new insights into therapeutic strategies targeting the vascular system.

DOT1L in neural development and neurological and psychotic disorders

Disruptor of Telomeric Silencing 1-Like (DOT1L) is the sole methyltransferase in mammals responsible for catalyzing the mono-, di-, and trimethylation of histone H3 at lysine 79 (H3K79), a modification crucial for various cellular processes, including gene transcription, cell cycle regulation, DNA repair, and development. Recent studies have increasingly linked DOT1L to the nervous system, where it plays a vital role in neurodevelopment and neuronal function. It has been shown to regulate the proliferation and differentiation of neural progenitor cells, promote neuronal maturation, and influence synaptic function, all of which are essential for proper neural circuit formation and brain function. Moreover, dysregulation of DOT1L has been associated with several neurological disorders, highlighting its potential role in disease pathology. Abnormal expression or activity of DOT1L has been implicated in cognitive deficits and neurodegenerative diseases, underscoring the enzyme's significance in both the development and maintenance of the nervous system. This review synthesizes recent findings on DOT1L's role in the nervous system, emphasizing its importance in neurodevelopment and exploring its potential as a therapeutic target for treating neurological disorders.

Glucose-derived receptors for photo-controlled binding of amino acid esters in water

Selective receptors of amino acids in aqueous media are highly sought after as they may enable the creation of novel diagnostic and sensing tools. Photoswitchable receptors are particularly attractive for such purposes as their response and selectivity towards bioanalytes can be modulated using light. Herein we report glucose-based photoswitchable receptors of amino-acid methyl esters and biogenic amines in water. The tetra-ortho-fluoroazobenzene unit in the receptors structure allows to control the distance between their binding sites using light. The Z-isomers of both receptors, having these sites in closer proximity, bind lysine, ornithine and arginine esters significantly stronger compared to E-isomers, where the binding sites are further apart.

Heterochromatin fidelity is a therapeutic vulnerability in lymphoma and other human cancers

Genes involved in the regulation of chromatin structure are frequently disrupted in cancer, contributing to an aberrant transcriptome and phenotypic plasticity. Yet, therapeutics targeting mutant forms of chromatin-modifying enzymes have yielded only modest clinical utility, underscoring the difficulty of targeting the epigenomic underpinnings of aberrant gene regulatory networks. Here, we sought to identify novel epigenetic vulnerabilities in diffuse large B-cell lymphoma (DLBCL). Through phenotypic screens and biochemical analysis, we demonstrated that inhibition of the H3K9 demethylases KDM4A and KDM4C elicits potent, subtype-agnostic cytotoxicity by antagonizing transcriptional networks associated with B-cell identity and epigenetically rewiring heterochromatin. KDM4 demethylases associated with the KRAB zinc finger ZNF587, and their enzymatic inhibition led to DNA replication stress and DNA damage-einduced cGAS-STING activation. Broad surveys of transcriptional data from patients also revealed KDM4 family dysregulation in several other cancer types. To explore this potential therapeutic avenue, we performed high-throughput small molecule screens with H3K9me3 nucleosome substrates and identified novel KDM4 demethylase inhibitors. AI-guided protein-ligand binding predictions suggested diverse modes of action for various small molecule hits. Our findings underscore the relevance of targeting fundamental transcriptional and epigenetic mechanisms for anti-cancer therapy.

Dual effect of targeting LSD1 on the invasiveness and the mechanical response of acute lymphoblastic leukemia cells

Epigenetic alterations are hallmarks of cancer, with histone modifiers playing critical roles in gene transcription, DNA homeostasis, and other nuclear functions. Lysine-specific demethylase 1 (LSD1), a key regulator of H3K4 methylation, has emerged as a promising pharmacological target in cancer treatment, including leukemia. Acute lymphoblastic leukemia (ALL), the most common pediatric cancer, remains a significant therapeutic challenge due to limited understanding of how epigenetic therapy impacts leukemia dissemination. In this study, we demonstrate that targeting LSD1 enhances the invasive capacity of ALL cells, inducing an elongated, invasive phenotype and increasing nuclear deformability. Using a 3D matrix model, LSD1 inhibition promoted ALL cell invasion without significantly affecting the cell cycle progression or apoptosis under the tested conditions. Interestingly, LSD1 targeting reduced ALL cell spreading and tissue colonization in vivo, suggesting differential effects depending on the cellular context. Our findings indicate that LSD1 inhibition impairs chemotactic responses and transendothelial migration, key processes for extravasation and in vivo invasiveness. These results reveal a dual role for LSD1 in leukemia cell migration: promoting invasiveness in 3D environments while reducing extravasation and chemotaxis in vivo. This dual effect underscores the importance of cellular context in determining therapeutic outcomes and the development of strategies targeting specific stages of leukemia dissemination.

A new target of multiple lysine methylation in bacteria

The methylation of ε-amino groups in protein lysine residues is an important posttranslational modification in eukaryotes. This modification plays a pivotal role in the regulation of diverse biological processes, including epigenetics, transcriptional control, and cellular signaling. Recent research has begun to reveal the potential role of methylation in modulating bacterial immune evasion and adherence to host cells. In this study, we analyzed the cell surface proteins of the toluene-degrading bacterium Acinetobacter sp. Tol 5 by label-free liquid chromatography‒mass spectrometry and found multiple lysine methylation in its trimeric autotransporter adhesin (TAA), AtaA. Over 130 lysine residues of AtaA, consisting of 3,630 amino acids and containing 234 lysine residues, were methylated. We identified that the outer membrane protein lysine methyltransferase (OM PKMT) of Tol 5, KmtA, specifically methylates the lysine residues of AtaA. In the KmtA-deficient mutant, most lysine methylations on AtaA were absent, indicating that KmtA is responsible for the methylation of multiple lysine residues throughout AtaA. Bioinformatic analysis revealed that the OM PKMT genes were widely distributed among Gram-negative bacteria, including pathogens with TAAs that promote infectivity, such as Burkholderia mallei and Haemophilus influenzae. Although KmtA has sequence similarities to the OM PKMTs of Rickettsia involved in infectivity, KmtA-like PKMTs formed a distinct cluster from those of the Rickettsia type according to the clustering analysis, suggesting that they are new types of OM PKMTs. Furthermore, the deletion of Tol 5 KmtA led to an increase in AtaA on the cell surface and enhanced bacterial adhesion, resulting in slower growth.

IMPORTANCE

Lysine methylation has been underexplored in prokaryotes, and information on it is limited to some pathogens. Our finding is the second case of multiple lysine methylation of bacterial outer membrane (OM) proteins, following that of OmpB of Rickettsia. The newly found target of methylation, AtaA, a trimeric autotransporter adhesin family protein of Acinetobacter sp. Tol 5 isolated from activated sludge, extends our understanding of OM protein methylation to non-pathogenic environmental strains. The newly identified enzyme KmtA shows higher specificity than rickettsial lysin methylases, protein lysine methyltransferases, and methylates more lysine residues of the target, which raises interest in the mechanism underlying its biological specificity. The widespread presence of KmtA-like PKMTs throughout Gram-negative bacteria suggests that lysine methylation functions more extensively in bacterial physiology than previously recognized.

Histone lysine methyltransferases and their specific methylation marks show significant changes in mouse testes from young to older ages

Spermatogenesis is finely regulated by histone methylation, which is crucial for regulating gene expression and chromatin remodeling. Functional studies have demonstrated that the histone lysine methyltransferases (KMTs) SETD1B, CFP1, SETDB1, G9A, and SETD2 play pivotal roles in spermatogenesis through establishing the key histone methylation marks, H3K4me3, H3K9me2, H3K9me3, and H3K36me3, respectively. This study aimed to evaluate the spatiotemporal expression of these KMTs and methylation marks as well as senescence-associated β-galactosidase (β-GAL), transcriptional activity, and apoptosis rates in mouse testes during biological aging. In accordance with these purposes, the following groups of Balb/C mice were created: young (1- and 2-week-old), prepubertal (3- and 4-week-old), pubertal (5- and 6-week-old), postpubertal (16-, 18-, and 20-week-old), and aged (48-, 50-, and 52-week-old). The β-GAL staining gradually increased from the young to the aged groups (P < 0.01). The SETD1B, G9A, SETDB1, and SETD2 protein levels increased in spermatogonia, early and pachytene spermatocytes, and Sertoli cells of the aged group (P < 0.05). In contrast, CFP1 protein level decreased in spermatogonia, pachytene spermatocytes, round spermatids, and Sertoli cells towards the older ages (P < 0.05). Moreover, H3K4me3, H3K9me2, H3K9me3, and H3K36me3 levels increased in the aged group (P < 0.05). There was also a significant reduction in apoptosis rates in seminiferous tubules of the pubertal, postpubertal, and aged groups (P < 0.01). Consequently, accumulation of histone methylation marks due to increased expression of KMTs in spermatogenic and Sertoli cells during testicular aging may alter chromatin reprogramming and gene expression, contributing to age-related fertility loss.

Novel role of zinc-finger protein 518 in heterochromatin formation on α-satellite DNA

Aneuploidy is caused by chromosomal missegregation and is frequently observed in cancers and hematological diseases. Therefore, it is important to understand the molecular mechanisms underlying chromosomal segregation. The centromere's intricate structure is crucial for proper chromosome segregation, with heterochromatin at the pericentromeric α-satellites playing a key role. However, the mechanism targeting heterochromatin to pericentromeres remains elusive. This study identifies a novel mechanism involving two homologous zinc-finger proteins ZNF518A and ZNF518B in human pericentric heterochromatin formation. Our investigation demonstrated that ZNF518s localize to the centromere via centromere protein B (CENP-B). Moreover, ZNF518s interact with heterochromatin protein 1 (HP1) and H3K9 methyltransferase G9A, recruiting the heterochromatin components to pericentromeres. We found that centromeric histone H3K9 trimethylation was diminished in the absence of ZNF518s when another H3K9 methyltransferase, SUV39H1, was depleted. In somatic cells, the ZNF518s-G9a axis is not the principal pathway for heterochromatin formation but plays a supplementary role. Furthermore, ZNF518s are involved in histone H3K9 trimethylation at ectopic sites, indicating their broad role in heterochromatin establishment. Consequently, we propose that ZNF518s participate in the mechanism underlying heterochromatin establishment at pericentromeres. Our findings shed light on the novel mechanism underlying pericentromeric heterochromatin formation, highlighting the central role of ZNF518 in this process.

A Method for Characterizing Protein-Histone Peptide Interactions In Vitro

Histone posttranslational modifications (PTMs) contribute to transcriptional regulation and generate in combination a "histone code," which is largely conserved among organismal kingdoms. By binding to specific PTMs, histone reader proteins act as molecular interpreters of the histone code. These proteins play a crucial role in gene regulation and chromatin structure by recruiting other proteins to the chromatin or blocking histone-modifying enzymes from accessing chromatin. Revealing the specificity of histone readers is, therefore, fundamental to understanding their function in gene regulation. Here, we describe a protocol to identify the binding specificity of histone readers to PTMs using histone peptide arrays and in vitro pull-down assays.

KDM1A epigenetically enhances RAD51 expression to suppress the STING-associated anti-tumor immunity in esophageal squamous cell carcinoma

Histone lysine demethylase LSD1, also known as KDM1A, has been found to regulate multiple cancer hallmarks since it was first identified in 2004. Recently, it has emerged as a promising target for stimulating anti-tumor immunity, specifically boosting T cell activity. However, it remains unclear whether and how it remodels the tumor microenvironment to drive oncogenic processes in esophageal squamous cell carcinoma (ESCC). In this study, protein levels in ESCC tissues were evaluated by immunostaining of tissue microarrays. Cell growth was assessed by colony formation assays in vitro and subcutaneous xenograft models in vivo. High-throughput transcriptomics and spatial immune proteomics were performed using bulk RNA sequencing and digital spatial profiling techniques, respectively. Epigenetic regulation of RAD51 by methylated histone proteins was analyzed using chromatin immunoprecipitated quantitative PCR assays. Finally, our clinical data indicate that KDM1A precisely predicts the overall survival of patients with early-stage ESCC. Inhibition of KDM1A blocked the growth of ESCC cells in vitro and in vivo. Mechanistically, our transcriptomics and spatial immune proteomics data, together with rescue assays, demonstrated that KDM1A specifically removes methyl residues from the histone protein H3K9me2, a transcription repressive marker, thus reducing its enrichment at the promoter of RAD51 to epigenetically reactivate its transcription. Additionally, it significantly inhibits the expression of NF-κB signaling-dependent proinflammatory genes IL-6 and IL-1B through RAD51, thus blocking the STING-associated anti-tumor immunity in stromal tumor-infiltrating lymphocytes (sTIL). Overall, our findings not only indicate that KDM1A is a promising target for ESCC patients at early stages but also provide novel mechanistic insights into its spatial regulation of STING-associated anti-tumor immunity in sTILs to drive the oncogenic processes in ESCC. The translation of these findings will ultimately guide more appropriate combinations of spatial immunotherapies with KDM1A inhibitors to improve the overall survival of specific subgroups in ESCC.

Investigating the differential structural organization and gene expression regulatory networks of lamin A Ig fold domain mutants of muscular dystrophy

Lamins form a proteinaceous meshwork as a major structural component of the nucleus. Lamins, along with their interactors, act as determinants for chromatin organization throughout the nucleus. The major dominant missense mutations responsible for autosomal dominant forms of muscular dystrophies reside in the Ig fold domain of lamin A. However, how lamin A contributes to the distribution of heterochromatin and balances euchromatin, and how it relocates epigenetic marks to shape chromatin states, remains poorly defined, making it difficult to draw conclusions about the prognosis of lamin A-mediated muscular dystrophies. In the first part of this report, we identified the in vitro organization of full-length lamin A proteins due to two well-documented Ig LMNA mutations, R453W and W514R. We further demonstrated that both lamin A/C mutant cells predominantly expressed nucleoplasmic aggregates. Labeling specific markers of epigenetics allowed correlation of lamin A mutations with epigenetic mechanisms. In addition to manipulating epigenetic mechanisms, our proteomic studies traced diverse expressions of transcription regulators, RNA synthesis and processing proteins, protein translation components, and posttranslational modifications. These data suggest severe perturbations in targeting other proteins to the nucleus.

Epigenetic control of dental stem cells: progress and prospects in multidirectional differentiation

Dental stem cells, with their exceptional proliferative capacity and multidirectional differentiation potential, hold significant promise for dental and oral tissue regeneration. Epigenetic inheritance, which involves stable and heritable changes in gene expression and function without alterations to the DNA sequence, plays a critical role in numerous biological processes. Environmental factors are particularly influential in epigenetic inheritance, as variations in exposure can lead to changes in epigenetic modifications that subsequently impact gene expression. Epigenetic mechanisms are widely involved in processes such as bone homeostasis, embryogenesis, stem cell fate determination, and disease development. Recently, the epigenetic regulation of dental stem cells has attracted considerable research attention. This paper reviews studies focused on the epigenetic mechanisms governing the multidirectional differentiation of dental stem cells.

Decreased histone H3K9 dimethylation in synergy with DNA demethylation of Spi-1 binding site contributes to ADAMTS-5 expression in articular cartilage of osteoarthritis mice

Osteoarthritis (OA) is defined by articular cartilage degeneration, synovial membrane inflammation, and abnormal bone remodeling. Recent study has discovered that OA development is linked to an aberrant epigenetic modification of OA-related genes. Our previous research showed that DNA demethylation in ADAMTS-5 promoter region had a substantial impact on ADAMTS-5 expression in the mouse OA model. This process facilitated the binding of Spi-1 to ADAMTS-5 promoter. While alterations in histone methylation have been documented during embryonic development and cancer development, there is a paucity of data on the change in OA pathogenesis. Even no data have been reported on the role of histone modifications in ADAMTS-5 activation in OA. Following our previous study on the role of DNA methylation, we aimed to examine the contribution of histone H3K9 dimethylation in ADAMTS-5 activation in OA. Additionally, we aimed to elucidate the molecular mechanisms underlying the cooperative interaction between DNA methylation and histone H3K9 dimethylation. The potential for anti-OA intervention therapy which is based on modulating histone H3K9 dimethylation is also explored. We demonstrated that a reduction in histone H3K9 dimethylation, along with DNA demethylation of the Spi-1 binding site, had a role in ADAMTS-5 activation in the articular cartilage of OA mice. Significantly, the conditional deletion of histone demethylase to be identified as lysine-specific demethylase 1 (LSD1) in articular cartilage could alleviate the degenerative features of OA mice. Our study demonstrates the direct impact of histone H3K9 dimethylation on gene expression, which in turn contributes to OA development. This research enhances our understanding of the underlying causes of OA.

Identification of grape H3K27 methyltransferase genes and their expression profiles during grape fruit ripening

BACKGROUND

H2O2 treatment can accelerate grape ripening and mediate changes in histone methylation levels. Histone methylation, as an epigenetic modification, is involved in regulating the expression of genes related to fruit ripening, including H3K27ac, H3K4me1, H3K27me3 and H3K4me3. Among them, H3K27me3 methylation is generally negatively regulated in development, and H3K27 methyltransferase can participate in the development process of fruit by regulate the level of H3K27me3. The H3K27 methyltransferase members in grapes are not yet clear, and a better understanding of their functions contributes to regulating fruit development.

METHODS AND RESULTS

By analyzing the conserved domains of the grape genome, three H3K27 methyltransferases were identified and named as VvH3K27-1, VvH3K27-2 and VvH3K27-3, respectively. Further analysis included their conserved domains, gene structure, phylogenetic relationship, protein physicochemical properties, chromosome localization, subcellular localization, and cis-acting elements in the promoter region. It is worth noting that all H3K27 methyltransferase genes have a highly conserved SET domain. VvH3K27-2 was localized in the nucleus and H2O2 treatment resulted in a decrease in the expression of these genes.

CONCLUSION

Three H3K27 methyltransferase genes were identified in grape, which are down-regulated during berry development, and their expression is inhibited by H2O2 treatment. Thus, H3K27 methyltransferase genes are involved in the regulation of fruit development.

Transcriptomic era of cancers in females: new epigenetic perspectives and therapeutic prospects

In the era of transcriptomics, the role of epigenetics in the study of cancers in females has gained increasing recognition. This article explores the impact of epigenetic modifications, such as DNA methylation, histone modification, and non-coding RNA, on cancers in females, including breast, cervical, and ovarian cancers (1). Our findings suggest that these epigenetic markers not only influence tumor onset, progression, and metastasis but also present novel targets for therapeutic intervention. Detailed analyses of DNA methylation patterns have revealed aberrant events in cancer cells, particularly promoter region hypermethylation, which may lead to silencing of tumor suppressor genes. Furthermore, we examined the complex roles of histone modifications and long non-coding RNAs in regulating the expression of cancer-related genes, thereby providing a scientific basis for developing targeted epigenetic therapies. Our research emphasizes the importance of understanding the functions and mechanisms of epigenetics in cancers in females to develop effective treatment strategies. Future therapeutic approaches may include drugs targeting specific epigenetic markers, which could not only improve therapeutic outcomes but also enhance patient survival and quality of life. Through these efforts, we aim to offer new perspectives and hope for the prevention, diagnosis, and treatment of cancers in females.

Tracing the Chromatin: From 3C to Live-Cell Imaging

Chromatin organization plays a key role in gene regulation throughout the cell cycle. Understanding the dynamics governing the accessibility of chromatin is crucial for insight into mechanisms of gene regulation, DNA replication, and cell division. Extensive research has been done to track chromatin dynamics to explain how cells function and how diseases develop, in the hope of this knowledge leading to future therapeutics utilizing proteins or drugs that modify the accessibility or expression of disease-related genes. Traditional methods for studying the movement of chromatin throughout the cell relied on cross-linking spatially adjacent sections or hybridizing fluorescent probes to chromosomal loci and then constructing dynamic models from the static data collected at different time points. While these traditional methods are fruitful in understanding fundamental aspects of chromatin organization, they are limited by their invasive sample preparation protocols and diffraction-limited microscope resolution. These limitations have been challenged by modern methods based on high- or super-resolution microscopy and specific labeling techniques derived from gene targeting tools. These modern methods are more sensitive and less invasive than traditional methods, therefore allowing researchers to track chromosomal organization, compactness, and even the distance or rate of chromatin domain movement in detail and real time. This review highlights a selection of recently developed methods of chromatin tracking and their applications in fixed and live cells.

A Chemoselective Enrichment Strategy for In-Depth Coverage of the Methyllysine Proteome

Proteomics is a powerful method to comprehensively understand cellular posttranslational modifications (PTMs). Owing to low abundance, tryptic peptides with PTMs are usually enriched for enhanced coverage by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Affinity chromatography for phosphoproteomes by metal-oxide and pan-specific antibodies for lysine acetylome allow identification of tens of thousands of modification sites. Lysine methylation is a significant PTM; however, only hundreds of methylation sites were identified by available approaches. Herein we report an aryl diazonium based chemoselective strategy that enables enrichment of monomethyllysine (Kme1) peptides through covalent bonds with extraordinary sensitivity. We identified more than 10000 Kme1 peptides from diverse cell lines and mouse tissues, which implied a wide lysine methylation impact on cellular processes. Furthermore, we found a significant amount of methyl marks that were not S-adenosyl methionine (SAM)-dependent by isotope labeling experiments.

Potent and Selective SETDB1 Covalent Negative Allosteric Modulator Reduces Methyltransferase Activity in Cells

A promising drug target, SETDB1, is a dual Kme reader and methyltransferase, which has been implicated in cancer and neurodegenerative disease progression. To help understand the role of the triple Tudor domain (3TD) of SETDB1, its Kme reader, we first identified a low micromolar small molecule ligand, UNC6535, which occupies simultaneously both the TD2 and TD3 reader binding sites. Further optimization led to the discovery of UNC10013, the first covalent 3TD ligand targeting Cys385 of SETDB1. UNC10013 is potent with a k inact /K I of 1.0 x 10 6 M -1 s -1 and demonstrated proteome-wide selectivity. In cells, negative allosteric modulation of SETDB1-mediated Akt methylation was observed after treatment with UNC10013. Therefore, UNC10013 is a potent, selective and cell-active covalent ligand for the 3TD of SETDB1, demonstrating negative allosteric modulator properties and making it a promising tool to study the biological role of SETDB1 in disease progression.

Functions and Mechanism of Thyroid Hormone Receptor Action During Amphibian Development

Thyroid hormones and their receptors (TRs) play critical roles during vertebrate development. One of the most dramatic developmental processes regulated by thyroid hormones is frog metamorphosis, which mimics the postembryonic (perinatal) period in mammals. Here, we review some of the findings on the developmental functions of thyroid hormones and TRs as well as their associated mechanisms of action obtained from this model system. More than 2 decades ago, a dual function model was proposed for TR in anuran development. During larval development, unliganded receptors recruit corepressors to repress thyroid hormone response genes to prevent premature metamorphic changes. Subsequently, when thyroid hormone levels rise, liganded receptors recruit coactivators to activate thyroid hormone response genes, leading to metamorphic changes. Over the years, molecular and genetic approaches have provided strong support for this model and have shown that it is applicable to mammalian development as well as to understanding the diverse effects of thyroid hormones in normal physiology and diseases caused by thyroid hormone signaling dysfunction.

Cracking the Code: Reprogramming the Genetic Script in Prokaryotes and Eukaryotes to Harness the Power of Noncanonical Amino Acids

Over 500 natural and synthetic amino acids have been genetically encoded in the last two decades. Incorporating these noncanonical amino acids into proteins enables many powerful applications, ranging from basic research to biotechnology, materials science, and medicine. However, major challenges remain to unleash the full potential of genetic code expansion across disciplines. Here, we provide an overview of diverse genetic code expansion methodologies and systems and their final applications in prokaryotes and eukaryotes, represented by Escherichia coli and mammalian cells as the main workhorse model systems. We highlight the power of how new technologies can be first established in simple and then transferred to more complex systems. For example, whole-genome engineering provides an excellent platform in bacteria for enabling transcript-specific genetic code expansion without off-targets in the transcriptome. In contrast, the complexity of a eukaryotic cell poses challenges that require entirely new approaches, such as striving toward establishing novel base pairs or generating orthogonally translating organelles within living cells. We connect the milestones in expanding the genetic code of living cells for encoding novel chemical functionalities to the most recent scientific discoveries, from optimizing the physicochemical properties of noncanonical amino acids to the technological advancements for their in vivo incorporation. This journey offers a glimpse into the promising developments in the years to come.

KDM4A promotes malignant progression of breast cancer by down-regulating BMP9 inducing consequent enhancement of glutamine metabolism

BACKGROUND

Recent studies have found that histone-modified genes play an increasingly important role in tumor progression. Lysine(K) specific demethylase 4A (KDM4A) is a histone lysine-specific demethylase highly expressed in a variety of malignant tumors, data showed that KDM4A was negatively correlated with the Bone Morphogenetic Protein 9 (BMP9) in breast cancer. And previous experiments have demonstrated that exogenous BMP9 significantly inhibits breast cancer development.

MATERIALS AND METHODS

We detected the expression of KDM4A in breast cancer and the relationship between KDM4A and BMP9 using real-time quantitative PCR (RT-qPCR) and Western blot, and verified the interaction between KDM4A and BMP9 by ChIP experiments. At the same time, we also detected whether KDM4A had effects on the RNA and protein stability of BMP9 using actinomycin D and cycloheximide. Measurement of alpha-ketoglutarate (α-KG) level by ELISA to observe the effect of BMP9 on glutamine metabolism in breast cancer cells. Nucleoplasmic distribution of KDM4A after exogenous BMP9 treatment in breast cancer cells were observed by immunofluorescence staining and Western blot. A subcutaneous xenograft tumor model in nude mice was used to study the therapeutic effects of exogenous BMP9 and KDM4A inhibitor (JIB-04) in breast cancer. CCK-8, conoly formation, Transwell, wound healing, and immunohistochemistry were used to monitor the growth of tumor and cell function.

RESULTS

We found that KDM4A was abnormally highly expressed in breast cancer, and silenced BMP9 expression by removing histone methyl groups from the BMP9 gene region. Meanwhile, KDM4A could also reduce the stability of BMP9 protein. BMP9 inhibit glutamine metabolism in breast cancer, resulting in a decrease in its product α-KG, is confirmed by ELISA. Altered nucleoplasmic distribution of KDM4A due to decreased α-KG was confirmed by immunofluorescence staining and Western blot. Animal experiments confirm that the combination of exogenous BMP9 and JIB-04 shows significantly better results in breast cancer.

CONCLUSIONS

KDM4A silences BMP9 expression by removing histone methyl groups from the BMP9 gene region, leading to further enhancement of glutamine metabolism, which contributes to malignant tumor progression. In addition, using JIB-04 in combination with exogenous BMP9 could inhibit the malignant progression of breast cancer cells and the growth of tumors more significantly.

Structure-based development of novel substrate-type G9a inhibitors as epigenetic modulators for sickle cell disease treatment

The discovery and development of structurally distinct lysine methyltransferase G9a inhibitors have been the subject of intense research in epigenetics. Structure-based optimization was conducted, starting with the previously reported seed compound 7a and lead to the identification of a highly potent G9a inhibitor, compound 7i (IC50 = 0.024 μM). X-ray crystallography for the ligand-protein interaction and kinetics study, along with surface plasmon resonance (SPR) analysis, revealed that compound 7i interacts with G9a in a unique binding mode. In addition, compound 7i caused attenuation of cellular H3K9me2 levels and induction of γ-globin mRNA expression in HUDEP-2 cells in a dose-dependent manner.

Metabolic labeling based methylome profiling enables functional dissection of histidine methylation in C3H1 zinc fingers

Protein methylation is a functionally important post-translational modification that occurs on diverse amino acid residues. The current proteomics approaches are inefficient to discover the methylation on residues other than Arg and Lys, which hinders the deep understanding of the functional role of rare protein methylation. Herein, we present a methyl-specific metabolic labeling approach for global methylome mapping, which enable the acquisition of methylome dataset covering diverse methylation types. Interestingly, of the identified methylation events, His methylation is found to be preferably occurred in C3H1 zinc fingers (ZFs). These His methylation events are determined to be Nπ specific and catalyzed by CARNMT1. The His methylation is found to stabilize the structure of ZFs. U2AF1 is used as a proof-of-concept to highlight the functional importance of His methylation in ZFs in RNA binding and RNA metabolism. The results of this study enable novel understanding of how protein methylation regulates cellular processes.

Functional Roles of H3K4 Methylation in Transcriptional Regulation

Histone 3 lysine 4 methylation (H3K4me) is a highly evolutionary conserved chromatin modification associated with active transcription, and its three methylation states-mono, di, and trimethylation-mark distinct regulatory elements. However, whether H3K4me plays functional roles in transcriptional regulation or is merely a by-product of histone methyltransferases recruited to actively transcribed loci is still under debate. Here, we outline the studies that have addressed this question in yeast, Drosophila, and mammalian systems. We review evidence from histone residue mutation, histone modifier manipulation, and epigenetic editing, focusing on the relative roles of H3K4me1 and H3K4me3. We conclude that H3K4me1 and H3K4me3 may have convergent functions in establishing open chromatin and promoting transcriptional activation during cell differentiation.

H3K36 methyltransferase GhKMT3;1a and GhKMT3;2a promote flowering in upland cotton

BACKGROUND

The SET domain group (SDG) genes encode histone lysine methyltransferases, which regulate gene transcription by altering chromatin structure and play pivotal roles in plant flowering determination. However, few studies have investigated their role in the regulation of flowering in upland cotton.

RESULTS

A total of 86 SDG genes were identified through genome-wide analysis in upland cotton (Gossypium hirsutum). These genes were unevenly distributed across 25 chromosomes. Cluster analysis revealed that the 86 GhSDGs were divided into seven main branches. RNA-seq data and qRT‒PCR analysis revealed that lysine methyltransferase 3 (KMT3) genes were expressed at high levels in stamens, pistils and other floral organs. Using virus-induced gene silencing (VIGS), functional characterization of GhKMT3;1a and GhKMT3;2a revealed that, compared with those of the controls, the GhKMT3;1a- and GhKMT3;2a-silenced plants exhibited later budding and flowering and lower plant heightwere shorter. In addition, the expression of flowering-related genes (GhAP1, GhSOC1 and GhFT) significantly decreased and the expression level of GhSVP significantly increased in the GhKMT3;1a- and GhKMT3;2a-silenced plants compared with the control plants.

CONCLUSION

A total of 86 SDG genes were identified in upland cotton, among which GhKMT3;1a and GhKMT3;2a might regulate flowering by affecting the expression of GhAP1, GhSOC1, GhFT and GhSVP. These findings will provide genetic resources for advanced molecular breeding in the future.

Uncovering genes involved in pollinator-driven mating system shifts and selfing syndrome evolution in Brassica rapa

Shifts in pollinator occurrence and their pollen transport effectiveness drive the evolution of mating systems in flowering plants. Understanding the genomic basis of these changes is essential for predicting the persistence of a species under environmental changes. We investigated the genomic changes in Brassica rapa over nine generations of pollination by hoverflies associated with rapid morphological evolution toward the selfing syndrome. We combined a genotyping-by-sequencing (GBS) approach with a genome-wide association study (GWAS) to identify candidate genes, and assessed their functional role in the observed morphological changes by studying mutations of orthologous genes in the model plant Arabidopsis thaliana. We found 31 candidate genes involved in a wide range of functions from DNA/RNA binding to transport. Our functional assessment of orthologous genes in A. thaliana revealed that two of the identified genes in B. rapa are involved in regulating the size of floral organs. We found a protein kinase superfamily protein involved in petal width, an important trait in plant attractiveness to pollinators. Moreover, we found a histone lysine methyltransferase (HKMT) associated with stamen length. Altogether, our study shows that hoverfly pollination leads to rapid evolution toward the selfing syndrome mediated by polygenic changes.

Targeting histone modifiers in bladder cancer therapy - preclinical and clinical evidence

Bladder cancer in the most advanced, muscle-invasive stage is lethal, and very limited therapeutic advances have been reported for decades. To date, cisplatin-based chemotherapy remains the first-line therapy for advanced bladder cancer. Late-line options have historically been limited. In the past few years, next-generation sequencing technology has enabled chromatin remodelling gene mutations to be characterized, showing that these alterations are more frequent in urothelial bladder carcinoma than in other cancer types. Histone modifiers have functional roles in tumour progression by modulating the expression of tumour suppressors and oncogenes and, therefore, have been considered as novel drug targets for cancer therapy. The roles of epigenetic reprogramming through histone modifications have been increasingly studied in bladder cancer, and the therapeutic efficacy of targeting those histone modifiers genetically or chemically is being assessed in preclinical studies. Results from preclinical studies in bladder cancer encouraged the investigation of some of these drugs in clinical trials, which yield mixed results. Further understanding of how alterations of histone modification mechanistically contribute to bladder cancer progression, drug resistance and tumour microenvironment remodelling will be required to facilitate clinical application of epigenetic drugs in bladder cancer.

PMTPred: machine-learning-based prediction of protein methyltransferases using the composition of k-spaced amino acid pairs

Protein methyltransferases (PMTs) are a group of enzymes that help catalyze the transfer of a methyl group to its substrates. These enzymes play an important role in epigenetic regulation and can methylate various substrates with DNA, RNA, protein, and small-molecule secondary metabolites. Dysregulation of methyltransferases is implicated in various human cancers. However, in light of the well-recognized significance of PMTs, reliable and efficient identification methods are essential. In the present work, we propose a machine-learning-based method for the identification of PMTs. Various sequence-based features were calculated, and prediction models were trained using various machine-learning algorithms using a tenfold cross-validation technique. After evaluating each model on the dataset, the SVM-based CKSAAP model achieved the highest prediction accuracy with balanced sensitivity and specificity. Also, this SVM model outperformed deep-learning algorithms for the prediction of PMTs. In addition, cross-database validation was performed to ensure the robustness of the model. Feature importance was assessed using shapley additive explanations (SHAP) values, providing insights into the contributions of different features to the model's predictions. Finally, the SVM-based CKSAAP model was implemented in a standalone tool, PMTPred, due to its consistent performance during independent testing and cross-database evaluation. We believe that PMTPred will be a useful and efficient tool for the identification of PMTs. The PMTPred is freely available for download at https://github.com/ArvindYadav7/PMTPred and http://www.bioinfoindia.org/PMTPred/home.html for research and academic use.

Histone modification in psoriasis: Molecular mechanisms and potential therapeutic targets

Psoriasis is an immune-mediated, inflammatory disease. Genetic and environmental elements are involved in the nosogenesis of this illness. Epigenetic inheritance serves as the connection between genetic and environmental factors. Histone modification, an epigenetic regulatory mechanism, is implicated in the development of numerous diseases. The basic function of histone modification is to regulate cellular functions by modifying gene expression. Modulation of histone modification, such as regulation of enzymes pertinent to histone modification, can be an alternative approach for treating some diseases, including psoriasis. Herein, we reviewed the regulatory mechanisms and biological effects of histone modifications and their roles in the pathogenesis of psoriasis.

Lysine methylation modifications in tumor immunomodulation and immunotherapy: regulatory mechanisms and perspectives

Lysine methylation is a crucial post-translational modification (PTM) that significantly impacts gene expression regulation. This modification not only influences cancer development directly but also has significant implications for the immune system. Lysine methylation modulates immune cell functions and shapes the anti-tumor immune response, highlighting its dual role in both tumor progression and immune regulation. In this review, we provide a comprehensive overview of the intrinsic role of lysine methylation in the activation and function of immune cells, detailing how these modifications affect cellular processes and signaling pathways. We delve into the mechanisms by which lysine methylation contributes to tumor immune evasion, allowing cancer cells to escape immune surveillance and thrive. Furthermore, we discuss the therapeutic potential of targeting lysine methylation in cancer immunotherapy. Emerging strategies, such as immune checkpoint inhibitors (ICIs) and chimeric antigen receptor T-cell (CAR-T) therapy, are being explored for their efficacy in modulating lysine methylation to enhance anti-tumor immune responses. By targeting these modifications, we can potentially improve the effectiveness of existing treatments and develop novel therapeutic approaches to combat cancer more effectively.

Noncanonical Amino Acids in Biocatalysis

In recent years, powerful genetic code reprogramming methods have emerged that allow new functional components to be embedded into proteins as noncanonical amino acid (ncAA) side chains. In this review, we will illustrate how the availability of an expanded set of amino acid building blocks has opened a wealth of new opportunities in enzymology and biocatalysis research. Genetic code reprogramming has provided new insights into enzyme mechanisms by allowing introduction of new spectroscopic probes and the targeted replacement of individual atoms or functional groups. NcAAs have also been used to develop engineered biocatalysts with improved activity, selectivity, and stability, as well as enzymes with artificial regulatory elements that are responsive to external stimuli. Perhaps most ambitiously, the combination of genetic code reprogramming and laboratory evolution has given rise to new classes of enzymes that use ncAAs as key catalytic elements. With the framework for developing ncAA-containing biocatalysts now firmly established, we are optimistic that genetic code reprogramming will become a progressively more powerful tool in the armory of enzyme designers and engineers in the coming years.

Epigenetic control of skeletal muscle atrophy

Skeletal muscular atrophy is a complex disease involving a large number of gene expression regulatory networks and various biological processes. Despite extensive research on this topic, its underlying mechanisms remain elusive, and effective therapeutic approaches are yet to be established. Recent studies have shown that epigenetics play an important role in regulating skeletal muscle atrophy, influencing the expression of numerous genes associated with this condition through the addition or removal of certain chemical modifications at the molecular level. This review article comprehensively summarizes the different types of modifications to DNA, histones, RNA, and their known regulators. We also discuss how epigenetic modifications change during the process of skeletal muscle atrophy, the molecular mechanisms by which epigenetic regulatory proteins control skeletal muscle atrophy, and assess their translational potential. The role of epigenetics on muscle stem cells is also highlighted. In addition, we propose that alternative splicing interacts with epigenetic mechanisms to regulate skeletal muscle mass, offering a novel perspective that enhances our understanding of epigenetic inheritance's role and the regulatory network governing skeletal muscle atrophy. Collectively, advancements in the understanding of epigenetic mechanisms provide invaluable insights into the study of skeletal muscle atrophy. Moreover, this knowledge paves the way for identifying new avenues for the development of more effective therapeutic strategies and pharmaceutical interventions.

The H3K4 demethylase JMJ1 is required for proper timing of flowering in Brachypodium distachyon

Flowering is a key developmental transition in the plant life cycle. In temperate climates, flowering often occurs in response to the perception of seasonal cues such as changes in day-length and temperature. However, the mechanisms that have evolved to control the timing of flowering in temperate grasses are not fully understood. We identified a Brachypodium distachyon mutant whose flowering is delayed under inductive long-day conditions due to a mutation in the JMJ1 gene, which encodes a Jumonji domain-containing protein. JMJ1 is a histone demethylase that mainly demethylates H3K4me2 and H3K4me3 in vitro and in vivo. Analysis of the genome-wide distribution of H3K4me1, H3K4me2, and H3K4me3 in wild-type plants by chromatin immunoprecipitation and sequencing combined with RNA sequencing revealed that H3K4m1 and H3K4me3 are positively associated with gene transcript levels, whereas H3K4me2 is negatively correlated with transcript levels. Furthermore, JMJ1 directly binds to the chromatin of the flowering regulator genes VRN1 and ID1 and affects their transcription by modifying their H3K4me2 and H3K4me3 levels. Genetic analyses indicated that JMJ1 promotes flowering by activating VRN1 expression. Our study reveals a role for JMJ1-mediated chromatin modification in the proper timing of flowering in B. distachyon.

A feedback loop driven by H3K9 lactylation and HDAC2 in endothelial cells regulates VEGF-induced angiogenesis

BACKGROUND

Vascular endothelial growth factor (VEGF) is one of the most powerful proangiogenic factors and plays an important role in multiple diseases. Increased glycolytic rates and lactate accumulation are associated with pathological angiogenesis.

RESULTS

Here, we show that a feedback loop between H3K9 lactylation (H3K9la) and histone deacetylase 2 (HDAC2) in endothelial cells drives VEGF-induced angiogenesis. We find that the H3K9la levels are upregulated in endothelial cells in response to VEGF stimulation. Pharmacological inhibition of glycolysis decreases H3K9 lactylation and attenuates neovascularization. CUT& Tag analysis reveals that H3K9la is enriched at the promoters of a set of angiogenic genes and promotes their transcription. Interestingly, we find that hyperlactylation of H3K9 inhibits expression of the lactylation eraser HDAC2, whereas overexpression of HDAC2 decreases H3K9 lactylation and suppresses angiogenesis.

CONCLUSIONS

Collectively, our study illustrates that H3K9la is important for VEGF-induced angiogenesis, and interruption of the H3K9la/HDAC2 feedback loop may represent a novel therapeutic method for treating pathological neovascularization.

Epigenetic Regulation of Neural Stem Cells in Developmental and Adult Stages

The development of the nervous system is regulated by numerous intracellular molecules and cellular signals that interact temporally and spatially with the extracellular microenvironment. The three major cell types in the brain, i.e., neurons and two types of glial cells (astrocytes and oligodendrocytes), are generated from common multipotent neural stem cells (NSCs) throughout life. However, NSCs do not have this multipotentiality from the beginning. During cortical development, NSCs sequentially obtain abilities to differentiate into neurons and glial cells in response to combinations of spatiotemporally modulated cell-intrinsic epigenetic alterations and extrinsic factors. After the completion of brain development, a limited population of NSCs remains in the adult brain and continues to produce neurons (adult neurogenesis), thus contributing to learning and memory. Many biological aspects of brain development and adult neurogenesis are regulated by epigenetic changes via behavioral control of NSCs. Epigenetic dysregulation has also been implicated in the pathogenesis of various brain diseases. Here, we present recent advances in the epigenetic regulation of NSC behavior and its dysregulation in brain disorders.

Proline-directed yeast and human MAP kinases phosphorylate the Dot1p/DOT1L histone H3K79 methyltransferase

Disruptor of telomeric silencing 1 (Dot1p) is an exquisitely conserved histone methyltransferase and is the sole enzyme responsible for H3K79 methylation in the budding yeast Saccharomyces cerevisiae. It has been shown to be highly phosphorylated in vivo; however, the upstream kinases that act on Dot1p are almost entirely unknown in yeast and all other eukaryotes. Here, we used in vitro and in vivo kinase discovery approaches to show that mitogen-activated protein kinase HOG1 (Hog1p) is a bona fide kinase of the Dot1p methyltransferase. In vitro kinase assays showed that Hog1p phosphorylates Dot1p at multiple sites, including at several proline-adjacent sites that are consistent with known Hog1p substrate preferences. The activity of Hog1p was specifically enhanced at these proline-adjacent sites on Dot1p upon Hog1p activation by the osmostress-responsive MAP kinase kinase PBS2 (Pbs2p). Genomic deletion of HOG1 reduced phosphorylation at specific sites on Dot1p in vivo, providing further evidence for Hog1p kinase activity on Dot1p in budding yeast cells. Phenotypic analysis of knockout and phosphosite mutant yeast strains revealed the importance of Hog1p-catalysed phosphorylation of Dot1p for cellular responses to ultraviolet-induced DNA damage. In mammalian systems, this kinase-substrate relationship was found to be conserved: human DOT1L (the ortholog of yeast Dot1p) can be phosphorylated by the proline-directed kinase p38β (also known as MAPK11; the ortholog of yeast Hog1p) at multiple sites in vitro. Taken together, our findings establish Hog1p and p38β as newly identified upstream kinases of the Dot1p/DOT1L H3K79 methyltransferase enzymes in eukaryotes.

Immunological landscape of solid cancer: Interplay between tumor and autoimmunity

The immune system, a central player in maintaining homeostasis, emerges as a pivotal factor in the pathogenesis and progression of two seemingly disparate yet interconnected categories of diseases: autoimmunity and cancer. This chapter delves into the intricate and multifaceted role of the immune system, particularly T cells, in orchestrating responses that govern the delicate balance between immune surveillance and self-tolerance. T cells, pivotal immune system components, play a central role in both diseases. In autoimmunity, aberrant T cell activation drives damaging immune responses against normal tissues, while in cancer, T cells exhibit suppressed responses, allowing the growth of malignant tumors. Immune checkpoint receptors, example, initially explored in autoimmunity, now revolutionize cancer treatment via immune checkpoint blockade (ICB). Though effective in various tumors, ICB poses risks of immune-related adverse events (irAEs) akin to autoimmunity. This chapter underscores the importance of understanding tumor-associated antigens and their role in autoimmunity, immune checkpoint regulation, and their implications for both diseases. It also explores autoimmunity resulting from cancer immunotherapy and shared molecular pathways in solid tumors and autoimmune diseases, highlighting their interconnectedness at the molecular level. Additionally, it sheds light on common pathways and epigenetic features shared by autoimmunity and cancer, and the potential of repurposing drugs for therapeutic interventions. Delving deeper into these insights could unlock therapeutic strategies for both autoimmunity and cancer.

Efficient Refinement of Complex Structures of Flexible Histone Peptides Using Post-Docking Molecular Dynamics Protocols

Histones are keys to many epigenetic events and their complexes have therapeutic and diagnostic importance. The determination of the structures of histone complexes is fundamental in the design of new drugs. Computational molecular docking is widely used for the prediction of target-ligand complexes. Large, linear peptides like the tail regions of histones are challenging ligands for docking due to their large conformational flexibility, extensive hydration, and weak interactions with the shallow binding pockets of their reader proteins. Thus, fast docking methods often fail to produce complex structures of such peptide ligands at a level appropriate for drug design. To address this challenge, and improve the structural quality of the docked complexes, post-docking refinement has been applied using various molecular dynamics (MD) approaches. However, a final consensus has not been reached on the desired MD refinement protocol. In this present study, MD refinement strategies were systematically explored on a set of problematic complexes of histone peptide ligands with relatively large errors in their docked geometries. Six protocols were compared that differ in their MD simulation parameters. In all cases, pre-MD hydration of the complex interface regions was applied to avoid the unwanted presence of empty cavities. The best-performing protocol achieved a median of 32% improvement over the docked structures in terms of the change in root mean squared deviations from the experimental references. The influence of structural factors and explicit hydration on the performance of post-docking MD refinements are also discussed to help with their implementation in future methods and applications.

Epigenetic contribution to the relationship between obesity and cancer

Obesity and cancer are two major health issues all around the world due to their elevated prevalence. Several experimental and epidemiological studies have demonstrated the relationship between obesity and cancer, in which obesity is considered a risk factor for cancer development. The ultimate goal of knowing the epigenetic contribution to the relationship between obesity and cancer is to find the method of intervention or treatment of obesity and cancer. Therefore, providing the most general perspective on epigenetic contribution to the relationship between obesity and cancer is necessary. Obesity is closely related to some common cancers that are currently encountered, including breast, esophagus, liver, kidney, uterus, colorectal, pancreatic, and gallbladder. Obesity has a significant impact that increases the risk of cancer deaths and thereby indirectly affects the choice of treatment. It is estimated that about 4-8% of cancer cases are caused by obesity. In particular, the basic mechanism to understand the relationship between cancer is very complicated and has not been fully understood. This work is aimed at summarizing the current knowledge of the role of epigenetic regulation in the relationship between obesity, and potential applications.

Unveiling the Molecular Landscape of Pancreatic Ductal Adenocarcinoma: Insights into the Role of the COMPASS-like Complex

Pancreatic ductal adenocarcinoma (PDAC) is poised to become the second leading cause of cancer-related death by 2030, necessitating innovative therapeutic strategies. Genetic and epigenetic alterations, including those involving the COMPASS-like complex genes, have emerged as critical drivers of PDAC progression. This review explores the genetic and epigenetic landscape of PDAC, focusing on the role of the COMPASS-like complex in regulating chromatin accessibility and gene expression. Specifically, we delve into the functions of key components such as KDM6A, KMT2D, KMT2C, KMT2A, and KMT2B, highlighting their significance as potential therapeutic targets. Furthermore, we discuss the implications of these findings for developing novel treatment modalities for PDAC.

Expanding the ligand spaces for E3 ligases for the design of protein degraders

Targeted protein degradation (TPD) has recently emerged as an exciting new drug modality. However, the strategy of developing small molecule-based protein degraders has evolved over the past two decades and has now established molecular tags that are already in clinical use, as well as chimeric molecules, PROteolysis TArgeting Chimeras (PROTACs), based mainly on ligand systems developed for the two E3 ligases CRBN and VHL. The large size of the human E3 ligase family suggests that PROTACs can be developed by targeting a large diversity of E3 ligases, some of which have restricted expression patterns with the potential to design disease- or tissue-specific degraders. Indeed, many new E3 ligands have been published recently, confirming the druggability of E3 ligases. This review summarises recent data on E3 ligases and highlights the challenges in developing these molecules into efficient PROTACs rivalling the established degrader systems.

Dynamics of epigenetic regulation in Dryophytes versicolor skeletal muscle: Lysine methylation and acetylation involvement in metabolic rate depression

For the breadth of the winter, Dryophytes versicolor can survive full body freezing utilizing a phenomenon known as metabolic rate depression (MRD). Epigenetic transcriptional control on gene expression, such as histone methylation and acetylation, can aid in implementing a balance between permissive and restricted chromatin required to endure this stress. As such, this study explores the interplay between histone lysine methyl and acetyl transferases (HKMTs, HATs), as well as the abundance of various acetyl-lysine and methyl-lysine moieties on histone H3 and H4. Results showing that overexpression of transcriptionally repressive marks, and under expression of active ones, suggest a negative effect on overall gene transcription in skeletal muscle tissue.

RNF187 governs the maintenance of mouse GC-2 cell development by facilitating histone H3 ubiquitination at K57/80

RING finger 187 (RNF187), a ubiquitin-ligating (E3) enzyme, plays a crucial role in the proliferation of cancer cells. However, it remains unclear whether RNF187 exhibits comparable functionality in the development of germline cells. To investigate the potential involvement of RNF187 in germ cell development, we conducted interference and overexpression assays using GC-2 cells, a mouse spermatocyte-derived cell line. Our findings reveal that the interaction between RNF187 and histone H3 increases the viability, proliferation, and migratory capacity of GC-2 cells. Moreover, we provide evidence demonstrating that RNF187 interacts with H3 and mediates the ubiquitination of H3 at lysine 57 (K57) or lysine 80 (K80), directly or indirectly resulting in increased cellular transcription. This is a study to report the role of RNF187 in maintaining the development of GC-2 cells by mediating histone H3 ubiquitination, thus highlighting the involvement of the K57 and K80 residues of H3 in the epistatic regulation of gene transcription. These discoveries provide a new theoretical foundation for further comprehensive investigations into the function of RNF187 in the reproductive system.

MLL1 histone methyltransferase and UTX histone demethylase functionally cooperate to regulate the expression of NRF2 in response to ROS-induced oxidative stress

The transcription factor NRF2 plays a pivotal role in maintaining redox and metabolic homeostasis by orchestrating oxidative stress-dependent transcription programs. Despite growing evidence implicating various cellular components in the regulation of NRF2 activity at the posttranslational stage, relatively less is known about the factors dictating the transcriptional activation of NRF2 in response to oxidative stress. In this study, we report the crucial roles of MLL1, an H3K4-specific methyltransferase, and UTX, an H3K27-specific histone demethylase, in the NRF2-dependent transcription program under oxidative stress. We find that the depletion of MLL1 or UTX results in increased susceptibility to oxidative stress, accompanied by higher intracellular ROS and the failed activation of antioxidant genes, including NRF2. In addition, MLL1 and UTX selectively target the NRF2 promoter, and exogenous FLAG-NRF2 expression increases the viability of MLL1-or UTX-depleted cells upon exposure to hydrogen peroxide. RNA-seq analysis demonstrates that depletion of MLL1 or UTX affects the changes in NRF2-dependent transcriptome in response to oxidative stress. Furthermore, ChIP and ChIP-seq analyses find that MLL1 and UTX functionally cooperate to establish a chromatin environment that favors active transcription at the H3K4me3/H3K27me3 bivalent NRF2 promoter in response to ROS-induced oxidative stress. Collectively, these findings provide a molecular mechanism underlying the cellular response to oxidative stress and highlight the importance of the chromatin structure and function in maintaining redox homeostasis.

LSD1 inhibition circumvents glucocorticoid-induced muscle wasting of male mice

Synthetic glucocorticoids (GC), such as dexamethasone, are extensively used to treat chronic inflammation and autoimmune disorders. However, long-term treatments are limited by various side effects, including muscle atrophy. GC activities are mediated by the glucocorticoid receptor (GR), that regulates target gene expression in various tissues in association with cell-specific co-regulators. Here we show that GR and the lysine-specific demethylase 1 (LSD1) interact in myofibers of male mice, and that LSD1 connects GR-bound enhancers with NRF1-associated promoters to stimulate target gene expression. In addition, we unravel that LSD1 demethylase activity is required for triggering starvation- and dexamethasone-induced skeletal muscle proteolysis in collaboration with GR. Importantly, inhibition of LSD1 circumvents muscle wasting induced by pharmacological levels of dexamethasone, without affecting their anti-inflammatory activities. Thus, our findings provide mechanistic insights into the muscle-specific GC activities, and highlight the therapeutic potential of targeting GR co-regulators to limit corticotherapy-induced side effects.

Extending MeCP2 interactome: canonical nucleosomal histones interact with MeCP2

MeCP2 is a general regulator of transcription involved in the repression/activation of genes depending on the local epigenetic context. It acts as a chromatin regulator and binds with exquisite specificity to gene promoters. The set of epigenetic marks recognized by MeCP2 has been already established (mainly, cytosine modifications in CpG and CpA), as well as many of the constituents of its interactome. We unveil a new set of interactions for MeCP2 with the four canonical nucleosomal histones. MeCP2 interacts with high affinity with H2A, H2B, H3 and H4. In addition, Rett syndrome associated mutations in MeCP2 and histone epigenetic marks modulate these interactions. Given the abundance and the structural/functional relevance of histones and their involvement in epigenetic regulation, this new set of interactions and its modulating elements provide a new addition to the 'alphabet' for this epigenetic reader.