Protein arginine methyltransferases (PRMTs): role in chromatin organization

Epigenetic targets and their inhibitors in the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a deadly lung disease characterized by fibroblast proliferation, excessive extracellular matrix buildup, inflammation, and tissue damage, resulting in respiratory failure and death. Recent studies suggest that impaired interactions among epithelial, mesenchymal, immune, and endothelial cells play a key role in IPF development. Advances in bioinformatics have also linked epigenetics, which bridges gene expression and environmental factors, to IPF. Despite the incomplete understanding of the pathogenic mechanisms underlying IPF, recent preclinical studies have identified several novel epigenetic therapeutic targets, including DNMT, EZH2, G9a/GLP, PRMT1/7, KDM6B, HDAC, CBP/p300, BRD4, METTL3, FTO, and ALKBH5, along with potential small-molecule inhibitors relevant for its treatment. This review explores the pathogenesis of IPF, emphasizing epigenetic therapeutic targets and potential small molecule drugs. It also analyzes the structure-activity relationships of these epigenetic drugs and summarizes their biological activities. The objective is to advance the development of innovative epigenetic therapies for IPF.

Unlocking the potential of histone modification in regulating bone metabolism

Bone metabolism plays a crucial role in maintaining normal bone tissue homeostasis and function. Imbalances between bone formation and resorption can lead to osteoporosis, osteoarthritis, and other bone diseases. The dynamic and complex process of bone remodeling is driven by various factors, including epigenetics. Histone modification, one of the most important and well-studied components of epigenetic regulation, has emerged as a promising area of research in bone metabolism. Different histone proteins and modification sites exert diverse effects on osteogenesis and osteoclastogenesis. In this review, we summarize recent progress in understanding histone modifications in bone metabolism, including specific modification sites and potential regulatory enzymes. Comprehensive knowledge of histone modifications in bone metabolism could reveal new therapeutic targets and treatment strategies for bone diseases.

Type I arginine methyltransferases play crucial roles in development and pathogenesis of Phytophthora capsici

Phytophthora capsici, a pathogenic oomycete, poses a serious threat to global vegetable production. This study investigated the role of protein arginine methylation, a notable post-translational modification, in the epigenetic regulation of P. capsici. We identified and characterized five protein arginine methyltransferases (PRMTs) in P. capsici, with a focus on four putative type I PRMTs exhibiting similar functional domain. Deletion of PcPRMT3, a homolog of PRMT3, significantly affected mycelial growth, asexual spore development, pathogenicity, and stress responses in P. capsici. Transcriptome analyses indicated that absence of PcPRMT3 disrupted multiple biological pathways. The PcPRMT3 deletion mutant displayed heightened susceptibility to oxidative stress, correlated with the downregulation of genes involved in peroxidase and peroxisome activities. Additionally, PcPRMT3 acted as a negative regulator, modulating the transcription levels of specific elicitins, which in turn affects the defense response of host plant against P. capsici. Furthermore, PcPRMT3 was found to affect global arginine methylation levels in P. capsici, implying potential alterations in the functions of its substrate proteins.

Epigenetic regulators controlling osteogenic lineage commitment and bone formation

Bone formation and homeostasis are controlled by environmental factors and endocrine regulatory cues that initiate intracellular signaling pathways capable of modulating gene expression in the nucleus. Bone-related gene expression is controlled by nucleosome-based chromatin architecture that limits the accessibility of lineage-specific gene regulatory DNA sequences and sequence-specific transcription factors. From a developmental perspective, bone-specific gene expression must be suppressed during the early stages of embryogenesis to prevent the premature mineralization of skeletal elements during fetal growth in utero. Hence, bone formation is initially inhibited by gene suppressive epigenetic regulators, while other epigenetic regulators actively support osteoblast differentiation. Prominent epigenetic regulators that stimulate or attenuate osteogenesis include lysine methyl transferases (e.g., EZH2, SMYD2, SUV420H2), lysine deacetylases (e.g., HDAC1, HDAC3, HDAC4, HDAC7, SIRT1, SIRT3), arginine methyl transferases (e.g., PRMT1, PRMT4/CARM1, PRMT5), dioxygenases (e.g., TET2), bromodomain proteins (e.g., BRD2, BRD4) and chromodomain proteins (e.g., CBX1, CBX2, CBX5). This narrative review provides a broad overview of the covalent modifications of DNA and histone proteins that involve hundreds of enzymes that add, read, or delete these epigenetic modifications that are relevant for self-renewal and differentiation of mesenchymal stem cells, skeletal stem cells and osteoblasts during osteogenesis.

Histone H4 asymmetrically dimethylated at arginine 3 (H4R3me2a), a mark of super-enhancers

Histone H4 asymmetrically dimethylated at arginine 3 (H4R3me2a) is an active histone mark catalyzed by protein arginine methyltransferase 1 (PRMT1), a major arginine methyltransferase in vertebrates catalyzing asymmetric dimethylation of arginine. H4R3me2a stimulates the activity of lysine acetyltransferases such as CBP/p300, which catalyze the acetylation of H3K27, a mark of active enhancers, super-enhancers, and promoters. There are a few studies on the genomic location of H4R3me2a. In chicken polychromatic erythrocytes, H4R3me2a is found in introns and intergenic regions and binds to the globin locus control region (a super-enhancer) and globin regulatory regions. In this report, we analyzed chromatin immunoprecipitation sequencing data for the genomic location of H4R3me2a in the breast cancer cell line MCF7. As in avian cells, MCF7 H4R3me2a is present in intronic and intergenic regions. Nucleosomes with H4R3me2a and H3K27ac next to nucleosome-free regions are found at super-enhancers, enhancers, and promoter regions of expressed genes. Genes with critical roles in breast cancer cells have broad domains of nucleosomes with H4R3me2a, H3K27ac, and H3K4me3. Our results are consistent with PRMT1-mediated H4R3me2a playing a key role in the chromatin organization of regulatory regions of vertebrate genomes.

Protein arginine methyltransferases PRMT1, PRMT4/CARM1 and PRMT5 have distinct functions in control of osteoblast differentiation

Osteogenic differentiation of mesenchymal cells is controlled by epigenetic enzymes that regulate post-translational modifications of histones. Compared to acetyl or methyltransferases, the physiological functions of protein arginine methyltransferases (PRMTs) in osteoblast differentiation remain minimally understood. Therefore, we surveyed the expression and function of all nine mammalian PRMT members during osteoblast differentiation. RNA-seq gene expression profiling shows that Prmt1, Prmt4/Carm1 and Prmt5 represent the most prominently expressed PRMT subtypes in mouse calvarial bone and MC3T3 osteoblasts as well as human musculoskeletal tissues and mesenchymal stromal cells (MSCs). Based on effects of siRNA depletion, it appears that PRMT members have different functional effects: (i) loss of Prmt1 stimulates and (ii) loss of Prmt5 decreases calcium deposition of mouse MC3T3 osteoblasts, while (iii) loss of Carm1 is inconsequential for calcium deposition. Decreased Prmt5 suppresses expression of multiple genes involved in mineralization (e.g., Alpl, Ibsp, Phospho1) consistent with a positive role in osteogenesis. Depletion of Prmt1, Carm1 and Prmt5 has intricate but modest time-dependent effects on the expression of a panel of osteoblast differentiation and proliferation markers but does not change mRNA levels for select epigenetic regulators (e.g., Ezh1, Ezh2, Brd2 and Brd4). Treatment with the Class I PRMT inhibitor GSK715 enhances extracellular matrix mineralization of MC3T3 cells, while blocking formation of H3R17me2a but not H4R3me2a marks. In sum, Prmt1, Carm1 and Prmt5 have distinct biological roles during osteoblast differentiation, and different types histone H3 and H4 arginine methylation may contribute to the chromatin landscape during osteoblast differentiation.

Overexpression of Leishmania major protein arginine methyltransferase 6 reduces parasite infectivity in vivo

Arginine methylation is catalysed by Protein Arginine Methyltransferases (PRMTs) and can affect how a target protein functions and how it interacts with other macromolecules, which in turn impacts on cell metabolism and gene expression control. Leishmania parasites express five different PRMTs, and although the presence of each individual PRMT is not essential per se, the imbalanced activity of these PRMTs can impact the virulence of Leishmania parasites in vitro and in vivo. Here we created a Leishmania major cell line overexpressing PRMT6 and show that similar to what was observed for the T. brucei homologous enzyme, L. major PRMT6 probably has a narrow substrate range. However, its overexpression notably impairs the infection in mice, with a mild reduction in the number of viable parasites in the lymph nodes. Our results indicate that arginine methylation by LmjPRMT6 plays a significant role in the adaptation of the parasite to the environment found in the mammalian host.

Targeting Arginine Methyltransferase PRMT5 for Cancer Therapy: Updated Progress and Novel Strategies

As a predominant type II protein arginine methyltransferase, PRMT5 plays critical roles in various normal cellular processes by catalyzing the mono- and symmetrical dimethylation of a wide range of histone and nonhistone substrates. Clinical studies have revealed that high expression of PRMT5 is observed in different solid tumors and hematological malignancies and is closely associated with cancer initiation and progression. Accordingly, PRMT5 is becoming a promising anticancer target and has received great attention in both the pharmaceutical industry and the academic community. In this Perspective, we comprehensively summarize recent advances in the development of first-generation PRMT5 enzymatic inhibitors and highlight novel strategies targeting PRMT5 in the past 5 years. We also discuss the challenges and opportunities of PRMT5 inhibition, with the aim of shedding light on future PRMT5 drug discovery.

Functional Study of Leishmania braziliensis Protein Arginine Methyltransferases (PRMTs) Reveals That PRMT1 and PRMT5 Are Required for Macrophage Infection

In trypanosomatids, regulation of gene expression occurs mainly at the posttranscriptional level, and RNA-binding proteins (RBPs) are key players in determining the fates of transcripts. RBPs are targets of protein arginine methyltransferases (PRMTs), which posttranslationally regulate the RNA-binding capacity and other RBP interactions by transferring methyl groups to arginine residues (R-methylation). Herein, we functionally characterized the five predicted PRMTs in Leishmania braziliensis by gene knockout and endogenous protein HA tagging using CRISPR/Cas9 gene editing. We report that R-methylation profiles vary among Leishmania species and across L. braziliensis lifecycle stages, with the peak PRMT expression occurring in promastigotes. A list of PRMT-interacting proteins was obtained in a single coimmunoprecipitation assay using HA-tagged PRMTs, suggesting a network of putative targets of PRMTs and cooperation between the R-methylation writers. Knockout of each L. braziliensis PRMT led to significant changes in global arginine methylation patterns without affecting cell viability. Deletion of either PRMT1 or PRMT3 disrupted most type I PRMT activity, resulting in a global increase in monomethyl arginine levels. Finally, we demonstrate that L. braziliensis PRMT1 and PRMT5 are required for efficient macrophage infection in vitro, and for axenic amastigote proliferation. The results indicate that R-methylation is modulated across lifecycle stages in L. braziliensis and show possible functional overlap and cooperation among the different PRMTs in targeting proteins. Overall, our data suggest important regulatory roles of these proteins throughout the L. braziliensis life cycle, showing that arginine methylation is important for parasite-host cell interactions.

Wnt activation promotes memory T cell polyfunctionality via epigenetic regulator PRMT1

T cell polyfunctionality is a hallmark of protective immunity against pathogens and cancer, yet the molecular mechanism governing it remains mostly elusive. We found that canonical Wnt agonists inhibited human memory CD8+ T cell differentiation while simultaneously promoting the generation of highly polyfunctional cells. Downstream effects of Wnt activation persisted after removal of the drug, and T cells remained polyfunctional following subsequent cell division, indicating the effect is epigenetically regulated. Wnt activation induced a gene expression pattern that is enriched with stem cell-specific gene signatures and upregulation of protein arginine methyltransferase 1 (PRMT1), a known epigenetic regulator. PRMT1+CD8+ T cells are associated with enhanced polyfunctionality, especially the ability to produce IL-2. In contrast, inhibition of PRMT1 ameliorated the effects of Wnt on polyfunctionality. Chromatin immunoprecipitation revealed that H4R3me2a, a permissive transcription marker mediated by PRMT1, increased at the IL-2 promoter loci following Wnt activation. In vivo, Wnt-treated T cells exhibited superior polyfunctionality and persistence. When applied to cytomegalovirus (CMV) donor-seropositive, recipient-seronegative patients (D+/R-) lung transplant patient samples, Wnt activation enhanced CMV-specific T cell polyfunctionality, which is important in controlling CMV diseases. These findings reveal a molecular mechanism governing T cell polyfunctionality and identify PRMT1 as a potential target for T cell immunotherapy.

Discovery of a potent and dual-selective bisubstrate inhibitor for protein arginine methyltransferase 4/5

Protein arginine methyltransferases (PRMTs) have been implicated in the progression of many diseases. Understanding substrate recognition and specificity of individual PRMT would facilitate the discovery of selective inhibitors towards future drug discovery. Herein, we reported the design and synthesis of bisubstrate analogues for PRMTs that incorporate a S-adenosylmethionine (SAM) analogue moiety and a tripeptide through an alkyl substituted guanidino group. Compound AH237 is a potent and selective inhibitor for PRMT4 and PRMT5 with a half-maximal inhibition concentration (IC50) of 2.8 and 0.42 nmol/L, respectively. Computational studies provided a plausible explanation for the high potency and selectivity of AH237 for PRMT4/5 over other 40 methyltransferases. This proof-of-principle study outlines an applicable strategy to develop potent and selective bisubstrate inhibitors for PRMTs, providing valuable probes for future structural studies.

Protein Arginine Methyltransferase 1 Is Essential for the Meiosis of Male Germ Cells

Protein arginine methyltransferase 1 (PRMT1) is a major enzyme responsible for the formation of methylarginine in mammalian cells; however, its function in vivo is not well understood due to its early embryonic lethality in null mice exhibiting spontaneous DNA damage, cell cycle delays, and defects in check point activation. Here, we generated germ cell-specific Prmt1 knock-out (KO) mice to evaluate the function of PRMT1 in spermatogenesis. Our findings demonstrate that PRMT1 is vital for male fertility in mice. Spermatogenesis in Prmt1 KO mice was arrested at the zygotene-like stage of the first meiotic division due to an elevated number of DNA double-strand breaks (DSBs). There was a loss of methylation in meiotic recombination 11 (MRE11), the key endonuclease in MRE11/RAD50/NBS 1 (MRN) complex, resulting in the accumulation of SPO11 protein in DSBs. The ATM-mediated negative feedback control over SPO11 was lost and, consequently, the repair pathway of DSBs was highly affected in PRMT1 deficient male germ cells. Our findings provide a novel insight into the role of PRMT1-mediated asymmetric demethylation in mouse spermatogenesis.

A Pan-Inhibitor for Protein Arginine Methyltransferase Family Enzymes

Protein arginine methyltransferases (PRMTs) play important roles in transcription, splicing, DNA damage repair, RNA biology, and cellular metabolism. Thus, PRMTs have been attractive targets for various diseases. In this study, we reported the design and synthesis of a potent pan-inhibitor for PRMTs that tethers a thioadenosine and various substituted guanidino groups through a propyl linker. Compound II757 exhibits a half-maximal inhibition concentration (IC50) value of 5 to 555 nM for eight tested PRMTs, with the highest inhibition for PRMT4 (IC50 = 5 nM). The kinetic study demonstrated that II757 competitively binds at the SAM binding site of PRMT1. Notably, II757 is selective for PRMTs over a panel of other methyltransferases, which can serve as a general probe for PRMTs and a lead for further optimization to increase the selectivity for individual PRMT.

Dysregulation of protein argininemethyltransferase in the pathogenesis of cancerpy

Arginine methylation is considered to be one of the most permanent and one of the most frequent post-translational modifications. The reaction of transferring a methyl group from S-adenosylmethionine to arginine residue is catalyzed by aginine methyltransferase (PRMT). In humans there are nine members of the PRMT family, named in order of discovery of PRMT1- PRMT9. Arginine methyltransferases were divided into three classes: I, II, III, with regard to the product of the catalyzed reaction. The products of their activity are, respectively, the following: asymmetric dimethylarginine (ADMA), symmetrical dimethylarginine (SDMA) and monomethylarginine (MMA). These modifications significantly affect the chromatin functions; therefore, they can act as co-activators or suppressors of the transcription process. Arginine methylation plays a crucial role in many biological processes in a human organism. Among others, it participates in signal transduction control, mRNA splicing and the regulation of basic cellular processes such as proliferation, differentiation, migration and apoptosis. There is increasing evidence that dysregulation of PRMT levels may lead to the cancer transformation of cells. The correlation between increased PRMT level and cancer has been demonstrated in the following: breast, ovary, lung and colorectal cancer. The activity of arginine methyltransferase can be regulated by small molecule PRMT inhibitors. To date, three substances that inhibit PRMT activity have been evaluated in clinical trials and exhibit anti-tumor activity against hematological cancer. It is believed that the use of specific PRMT inhibitors may become a new, effective and safe treatment of oncological diseases.

PRMT5: a putative oncogene and therapeutic target in prostate cancer

Protein arginine methyltransferase 5 (PRMT5) was discovered two decades ago. The first decade focused on the biochemical characterization of PRMT5 as a regulator of many cellular processes in a healthy organism. However, over the past decade, evidence has accumulated to suggest that PRMT5 may function as an oncogene in multiple cancers via both epigenetic and non-epigenetic mechanisms. In this review, we focus on recent progress made in prostate cancer, including the role of PRMT5 in the androgen receptor (AR) expression and signaling and DNA damage response, particularly DNA double-strand break repair. We also discuss how PRMT5-interacting proteins that are considered PRMT5 cofactors may cooperate with PRMT5 to regulate PRMT5 activity and target gene expression, and how PRMT5 can interact with other epigenetic regulators implicated in prostate cancer development and progression. Finally, we suggest that targeting PRMT5 may be employed to develop multiple therapeutic approaches to enhance the treatment of prostate cancer.

Asymmetrical arginine dimethylation of histone H4 by 8-oxog/OGG1/PRMT1 is essential for oxidative stress-induced transcription activation

It has been established that 8-oxoguanine DNA glycosylase 1 (OGG1) is the main enzyme removing oxidized guanine under oxidative stress. However, increasing evidence has shown that OGG1 is not only a base excision repair protein but also a new transcriptional coactivator involved in oxidative stress-induced gene expression. Its downstream target genes and the underlying regulatory mechanisms still need to be discerned. Here, it was discovered that c-Myc is a downstream target of OGG1 under oxidative stress and that H4R3me2a is involved in this transcriptional regulation. The increased level of H4R3me2a induced by H₂O₂ is regulated by OGG1, which may directly interact with the specific arginine methyltransferase PRMT1 and promote the asymmetrical dimethylation of H4R3me1. H4R3me2a enrichment on the promoter of c-Myc can recruit YY1 and activate c-Myc transcription. Moreover, knocking down OGG1 or PRMT1 suppresses c-Myc transcription under oxidative stress by downregulating H4R3me2a formation. Furthermore, the overexpression of wild type (WT) H4R3 promotes c-Myc transcription, but the expression of mutant H4R3Q does not have this effect. Taken together, our data show that the 8-oxoG/OGG1/PRMT1/H4R3me2a/YY1 axis senses oxidative stress and promotes gene transcription.

Perinatal inflammation alters histone 3 and histone 4 methylation patterns: Effects of MiR-29b supplementation

Preterm birth is still a major health problem and maternal inflammation has been shown to play a role. The combination of maternal inflammation and neonatal hyperoxia contributes to epigenetic changes that influence gene expression and the development of bronchopulmonary dysplasia (BPD). We have previously demonstrated suppression of miR-29b and increases in DNA methylation in infants with severe BPD and in our mouse model of maternal inflammation and neonatal hyperoxia exposure. The present studies further explored epigenetic changes in the murine model to include histone methylation. We identified a global suppression of histone methylation in exposed mice and validated decreases in expression in well-defined histone modifications, specifically H3K4me3, H3K27me3, H3K36me2, H3K79me2, and H4K20me3. We further tested the hypothesis that restoration of miR-29b expression would restore the histone methylation marks. Using lipid nanoparticle delivery of miR-29b, partial to full methylation was reestablished for H3K4me3, H3K27me3, and H4K20me3; all tri-methylation marks. To identify the causes of decreased methylation in exposed mice, we measured commonly identified methylases and demethylases. We found a decreased expression of SUV40H2, a methylase primarily associated with H4K20me3. Further studies are needed to identify the causes for the decreased global histone methylation and potential therapeutic opportunities.

Symmetrical dimethylation of H4R3: A bridge linking DNA damage and repair upon oxidative stress

The DNA lesions caused by oxidative damage are principally repaired by the base excision repair (BER) pathway. 8-oxoguanine DNA glycosylase 1 (OGG1) initiates BER through recognizing and cleaving the oxidatively damaged nucleobase 8-oxo-7,8-dihydroguanine (8-oxoG). How the BER machinery detects and accesses lesions within the context of chromatin is largely unknown. Here, we found that the symmetrical dimethylarginine of histone H4 (producing H4R3me2s) serves as a bridge between DNA damage and subsequent repair. Intracellular H4R3me2s was significantly increased after treatment with the DNA oxidant reagent H2O2, and this increase was regulated by OGG1, which could directly interact with the specific arginine methyltransferase, PRMT5. Arginine-methylated H4R3 could associate with flap endonuclease 1 (FEN1) and enhance its nuclease activity and BER efficiency. Furthermore, cells with a decreased level of H4R3me2s were more susceptible to DNA-damaging agents and accumulated more DNA damage lesions in their genome. Taken together, these results demonstrate that H4R3me2s can be recognized as a reader protein that senses DNA damage and a writer protein that promotes DNA repair.

SARS-CoV-2 multifaceted interaction with the human host. Part II: Innate immunity response, immunopathology, and epigenetics

The SARS-CoV-2 makes its way into the cell via the ACE2 receptor and the proteolytic action of TMPRSS2. In response to the SARS-CoV-2 infection, the innate immune response is the first line of defense, triggering multiple signaling pathways to produce interferons, pro-inflammatory cytokines and chemokines, and initiating the adaptive immune response against the virus. Unsurprisingly, the virus has developed strategies to evade detection, which can result in delayed, excessive activation of the innate immune system. The response elicited by the host depends on multiple factors, including health status, age, and sex. An overactive innate immune response can lead to a cytokine storm, inflammation, and vascular disruption, leading to the vast array of symptoms exhibited by COVID-19 patients. What is known about the expression and epigenetic regulation of the ACE2 gene and the various players in the host response are explored in this review.

METTL7B Is Required for Cancer Cell Proliferation and Tumorigenesis in Non-Small Cell Lung Cancer

Lung cancer remains a leading cause of cancer-associated mortality worldwide, however, molecular mechanisms underlying lung cancer tumorigenesis and progression remain unknown. Here, we report evidence showing that one member of the mammalian methyltransferase-like family (METTL), METTL7B, is a potential molecular target for treatment of non-small cell lung cancer (NSCLC). METTL7B expression was elevated in the majority of NSCLC comparing to normal tissues. Increased expression of METTL7B contributed to advanced stages of tumor development and poor survival in NSCLC patients. Lentivirus-mediated shRNA silencing of METTL7B suppressed proliferation and tumorigenesis of cancer cells in vitro and in vivo. Investigation on gene expression profiles of NSCLC cells revealed that abundant cell cycle related genes were downregulated in the absence of METTL7B. Pathway enrichment analysis indicated that METTL7B participated in cell cycle regulation. Notably, CCND1, a key regulator for G1/S transition, was significantly decreased with the depletion of METTL7B, resulting in G0/G1 arrest, indicating that METTL7B is critical for cell cycle progression. Taken together, our findings implicate that METTL7B is essential for NSCLC development and progression. METTL7B might serve as a potential therapeutic target for NSCLC.

Structural and biochemical evaluation of bisubstrate inhibitors of protein arginine N-methyltransferases PRMT1 and CARM1 (PRMT4)

Attenuating the function of protein arginine methyltransferases (PRMTs) is an objective for the investigation and treatment of several diseases including cardiovascular disease and cancer. Bisubstrate inhibitors that simultaneously target binding sites for arginine substrate and the cofactor (S-adenosylmethionine (SAM)) have potential utility, but structural information on their binding is required for their development. Evaluation of bisubstrate inhibitors featuring an isosteric guanidine replacement with two prominent enzymes PRMT1 and CARM1 (PRMT4) by isothermal titration calorimetry (ITC), activity assays and crystallography are reported. Key findings are that 2-aminopyridine is a viable replacement for guanidine, providing an inhibitor that binds more strongly to CARM1 than PRMT1. Moreover, a residue around the active site that differs between CARM1 (Asn-265) and PRMT1 (Tyr-160) is identified that affects the side chain conformation of the catalytically important neighbouring glutamate in the crystal structures. Mutagenesis data supports its contribution to the difference in binding observed for this inhibitor. Structures of CARM1 in complex with a range of seven inhibitors reveal the binding modes and show that inhibitors with an amino acid terminus adopt a single conformation whereas the electron density for equivalent amine-bearing inhibitors is consistent with preferential binding in two conformations. These findings inform the molecular basis of CARM1 ligand binding and identify differences between CARM1 and PRMT1 that can inform drug discovery efforts.

Non-Histone Arginine Methylation by Protein Arginine Methyltransferases

Protein arginine methyltransferase (PRMT) enzymes play a crucial role in RNA splicing, DNA damage repair, cell signaling, and differentiation. Arginine methylation is a prominent posttransitional modification of histones and various non-histone proteins that can either activate or repress gene expression. The aberrant expression of PRMTs has been linked to multiple abnormalities, notably cancer. Herein, we review a number of non-histone protein substrates for all nine members of human PRMTs and how PRMT-mediated non-histone arginine methylation modulates various diseases. Additionally, we highlight the most recent clinical studies for several PRMT inhibitors.

Rapid and direct measurement of methyltransferase activity in about 30 min

Protein arginine methylation is a widespread eukaryotic posttranslational modification that occurs to both histone and non-histone proteins. The S-adenosyl-L-methionine (AdoMet or SAM)-dependent modification is catalyzed by the protein arginine methyltransferase (PRMT) family of enzymes. In the last several years a series of both direct and indirect assay formats have been described that allow the rate of methylation to be measured. Here we provide a detailed protocol to directly measure PRMT activity using radiolabeled AdoMet, reversed-phase resin-filled pipette tips (ZipTips®) and a liquid scintillation counter. Because the ZipTips® based quantitation relies only on the straightforward separation of unreacted AdoMet from a methylated substrate, this protocol should be readily adaptable to other methyltransferases. The method is fast, simple to employ with both peptide and protein substrates, and produces very little radioactive waste.

The complex CBX7-PRMT1 has a critical role in regulating E-cadherin gene expression and cell migration

The Chromobox protein homolog 7 (CBX7) belongs to the Polycomb Group (PcG) family, and, as part of the Polycomb repressive complex (PRC1), contributes to maintain transcriptional gene repression. Loss of CBX7 expression has been reported in several human malignant neoplasias, where it often correlates with an advanced cancer state and poor survival, proposing CBX7 as a candidate tumor-suppressor gene in cancer progression. Indeed, CBX7 is able to positively or negatively regulate the expression of genes involved in cell proliferation and cancer progression, such as E-cadherin, cyclin E, osteopontin, EGR1. To understand the molecular mechanisms that underlie the involvement of CBX7 in cancer progression, we designed a functional proteomic experiment based on CHIP-MS to identify novel CBX7 protein partners. Among the identified CBX7-interacting proteins we focused our attention on the Protein Arginine Methyltransferase 1 (PRMT1) whose critical role in epithelial-mesenchymal transition (EMT), cancer cell migration and invasion has been already reported. We confirmed the interaction between CBX7 and PRMT1 and demonstrated that this interaction is crucial for PRMT1 enzymatic activity both in vitro and in vivo and for the regulation of E-cadherin expression, an important hallmark of EMT. These results suggest a general mechanism by which CBX7 interacting with histone modification enzymes like HDAC2 and PRMT1 enhances E-cadherin expression. Therefore, disruption of this equilibrium may induce impairment of E-cadherin expression and increased cell migration eventually leading to EMT and, then, cancer progression.

Mitogen and stress- activated protein kinase regulated gene expression in cancer cells

The mitogen- and stress-activated protein kinases activated by the extracellular-signal-regulated kinase 1/2 and/or stress-activated protein kinase 2/p38 mitogen-activated protein kinase pathways are recruited to the regulatory region of a subset of genes termed immediate-early genes, often leading to their induction. These genes, many of which code for transcription factors, have been directly linked to the phenotypic events in carcinogenesis. In this paper, we focus on the mitogen- and stress-activated protein kinases; their discovery, activation, H3 phosphorylation and recent discoveries in their roles in cancer.

Insights on the epigenetic mechanisms underlying pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH), characterized by localized increased arterial blood pressure in the lungs, is a slow developing long-term disease that can be fatal. PAH is characterized by inflammation, vascular tone imbalance, pathological pulmonary vascular remodeling, and right-sided heart failure. Current treatments for PAH are palliative and development of new therapies is necessary. Recent and relevant studies have demonstrated that epigenetic processes may exert key influences on the pathogenesis of PAH and may be promising therapeutic targets in the prevention and/or cure of this condition. The aim of the present mini-review is to summarize the occurrence of epigenetic-based mechanisms in the context of PAH physiopathology, focusing on the roles of DNA methylation, histone post-translational modifications and non-coding RNAs. We also discuss the potential of epigenetic-based therapies for PAH.

Epigenetic modifications in chronic myeloid leukemia cells through ruxolitinib treatment

Chronic myeloid leukemia is a clonal malignancy of hematopoietic stem cell that is characterized by the occurrence of t(9;22)(q34;q11.2) translocation, named Philadelphia chromosome. Ruxolitinib is a powerful Janus tyrosine kinase 1 and 2 inhibitor that is used for myelofibrosis treatment. DNA-histone connection mediates a wide range of genes that code methylation, demethylation, acetylation, deacetylation, ubiquitination, and phosphorylation enzymes. Epigenetic modifications regulate chromatin compactness, which plays pivotal roles in critical biological processes including the transcriptional activity and cell proliferation as well as various pathological mechanisms, including CML. This study is aimed to determine the alterations of the expression levels of epigenetic modification-related genes after ruxolitinib treatment. Total RNA was isolated from K-562 cells treated with the IC₅₀ value of ruxolitinib and untreated K-562 control cells. A reverse transcription procedure was performed for complementary DNA synthesis, and gene expressions were detected by real-time polymerase chain reaction compared with the untreated cells. Ruxolitinib treatment caused a significant alteration in the expression levels of epigenetic regulation-related genes in K-562 cells. Our novel results suggested that ruxolitinib has inhibitor effects on epigenetic modification-regulator genes.

Protein Arginine Methyltransferase 5 (PRMT5) as an Anticancer Target and Its Inhibitor Discovery

PRMT5 is a major enzyme responsible for symmetric dimethylation of arginine residues on both histone and non-histone proteins, regulating many biological pathways in mammalian cells. PRMT5 has been suggested as a therapeutic target in a variety of diseases including infectious disease, heart disease, and cancer. Many PRMT5 inhibitors have been discovered in the past 5 years, and one entered clinical trial in 2015 for the treatment of solid tumor and mantle cell lymphoma (MCL). The aim of this review is to summarize the current understanding of the roles of PRMT5 in cancer and the discovery of PRMT5 enzymatic inhibitors. By reviewing the structure-activity relationship (SAR) of known inhibitors of PRMT5, we hope to provide guidance for future drug designs and inhibitor optimization. Opportunities and limitations of PRMT5 inhibitors for the treatment of cancer are also discussed.

Alteration of DACH1 methylation patterns in lung cancer contributes to cell proliferation and migration

Lung cancer is the most common cause of cancer-related death. Non-small cell lung cancer (NSCLC) accounts for 80%-85% of total lung cancer cases. Dachshund homolog 1 (DACH1), is a protein encoded by the DACH1 gene in humans. DACH1 inhibits lung adenocarcinoma invasion and tumor growth but has a lower expression in NSCLC. To investigate the mechanisms of decreased DACH1 expression, its DNA methylation patterns were investigated. The results showed a higher methylation rate in NSCLC compared with the adjacent normal lung tissues. Cell transfection experiments showed that increased methylation impaired transcription factor transactivation. In vivo demethylation treatment and overexpression of DACH1 increased apoptosis and decreased migration and invasion in NSCLC A549 cells. Our research provides new insight into NSCLC pathogenesis and identifies a new therapeutic target.

Effects of berberine, curcumin, resveratrol alone and in combination with chemotherapeutic drugs and signal transduction inhibitors on cancer cells-Power of nutraceuticals

Over the past fifty years, society has become aware of the importance of a healthy diet in terms of human fitness and longevity. More recently, the concept of the beneficial effects of certain components of our diet and other compounds, that are consumed often by different cultures in various parts of the world, has become apparent. These "healthy" components of our diet are often referred to as nutraceuticals and they can prevent/suppress: aging, bacterial, fungal and viral infections, diabetes, inflammation, metabolic disorders and cardiovascular diseases and have other health-enhancing effects. Moreover, they are now often being investigated because of their anti-cancer properties/potentials. Understanding the effects of various natural products on cancer cells may enhance their usage as anti-proliferative agents which may be beneficial for many health problems. In this manuscript, we discuss and demonstrate how certain nutraceuticals may enhance other anti-cancer drugs to suppress proliferation of cancer cells.

Sulforaphane suppresses PRMT5/MEP50 function in epidermal squamous cell carcinoma leading to reduced tumor formation

Protein arginine methyltransferase 5 (PRMT5) cooperates with methylosome protein 50 (MEP50) to arginine methylate histone H3 and H4 to silence gene expression, and increased PRMT5 activity is associated with enhanced cancer cell survival. We have studied the role of PRMT5 and MEP50 in epidermal squamous cell carcinoma. We show that knockdown of PRMT5 or MEP50 results in reduced H4R3me2s formation, and reduced cell proliferation, invasion, migration and tumor formation. We further show that treatment with sulforaphane (SFN), a cancer preventive agent derived from cruciferous vegetables, reduces PRMT5 and MEP50 level and H4R3me2s formation, and this is associated with reduced cell proliferation, invasion and migration. The SFN-dependent reduction in PRMT5 and MEP50 level requires proteasome activity. Moreover, SFN-mediated responses are partially reversed by forced PRMT5 or MEP50 expression. SFN treatment of tumors results in reduced MEP50 level and H4R3me2s formation, confirming that that SFN impacts this complex in vivo. These studies suggest that the PRMT5/MEP50 is required for tumor growth and that reduced expression of this complex is a part of the mechanism of SFN suppression of tumor formation.

Regulation of GSK-3 activity by curcumin, berberine and resveratrol: Potential effects on multiple diseases

Natural products or nutraceuticals promote anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of the PI3K/PTEN/Akt/mTORC1/GSK-3 pathway. This review will focus on the effects of curcumin (CUR), berberine (BBR) and resveratrol (RES), on the PI3K/PTEN/Akt/mTORC1/GSK-3 pathway, with a special focus on GSK-3. These natural products may regulate the pathway by multiple mechanisms including: reactive oxygen species (ROS), cytokine receptors, mirco-RNAs (miRs) and many others. CUR is present the root of turmeric (Curcuma longa). CUR is used in the treatment of many disorders, especially in those involving inflammatory processes which may contribute to abnormal proliferation and promote cancer growth. BBR is also isolated from various plants (Berberis coptis and others) and is used in traditional medicine to treat multiple diseases/conditions including: diabetes, hyperlipidemia, cancer and bacterial infections. RES is present in red grapes, other fruits and berries such as blueberries and raspberries. RES may have some anti-diabetic and anti-cancer effects. Understanding the effects of these natural products on the PI3K/PTEN/Akt/mTORC1/GSK-3 pathway may enhance their usage as anti-proliferative agent which may be beneficial for many health problems.

Tungsten exposure causes a selective loss of histone demethylase protein

In the course of our investigations into the toxicity of tungstate, we discovered that cellular exposure resulted in the loss of the histone demethylase protein. We specifically investigated the loss of two histone demethylase dioxygenases, JARID1A and JMJD1A. Both of these proteins were degraded in the presence of tungstate and this resulted in increased global levels of H3K4me3 and H3K9me2, the substrates of JARID1A and JMJD1A, respectively. Treatment with MG132 completely inhibited the loss of the demethylase proteins induced by tungstate treatment, suggesting that tungstate activated the proteasomal degradation of these proteins. The changes in global histone marks and loss of histone demethylase protein persisted for at least 48 h after removing sodium tungstate from the culture. The increase in global histone methylation remained when cells were cultured in methionine-free media, indicating that the increased histone methylation did not depend upon any de novo methylation process, but rather was due to the loss of the demethylase protein. Similar increases of H3K4me3 and H3K9me2 were observed in the livers of the mice that were acutely exposed to tungstate via their drinking water. Taken together, our results indicated that tungstate exposure specifically reduced histone demethylase JARID1A and JMJD1A via proteasomal degradation, leading to increased histone methylation.

Protein arginine methyltransferases interact with intraflagellar transport particles and change location during flagellar growth and resorption

Protein arginine methyl transferases are located at specific sites in the flagellum. They change location during changes in flagellar dynamics (i.e., resorption and regeneration) via interaction with intraflagellar transport trains.

Changes in protein by posttranslational modifications comprise an important mechanism for the control of many cellular processes. Several flagellar proteins are methylated on arginine residues during flagellar resorption; however, the function is not understood. To learn more about the role of protein methylation during flagellar dynamics, we focused on protein arginine methyltransferases (PRMTs) 1, 3, 5, and 10. These PRMTs localize to the tip of flagella and in a punctate pattern along the length, very similar, but not identical, to that of intraflagellar transport (IFT) components. In addition, we found that PRMT 1 and 3 are also highly enriched at the base of the flagella, and the basal localization of these PRMTs changes during flagellar regeneration and resorption. Proteins with methyl arginine residues are also enriched at the tip and base of flagella, and their localization also changes during flagellar assembly and disassembly. PRMTs are lost from the flagella of fla10-1 cells, which carry a temperature-sensitive mutation in the anterograde motor for IFT. The data define the distribution of specific PRMTs and their target proteins in flagella and demonstrate that PRMTs are cargo for translocation within flagella by the process of IFT.

Network-based characterization of the synaptic proteome reveals that removal of epigenetic regulator Prmt8 restricts proteins associated with synaptic maturation

The brain adapts to dynamic environmental conditions by altering its epigenetic state, thereby influencing neuronal transcriptional programs. An example of an epigenetic modification is protein methylation, catalyzed by protein arginine methyltransferases (PRMT). One member, Prmt8, is selectively expressed in the central nervous system during a crucial phase of early development, but little else is known regarding its function. We hypothesize Prmt8 plays a role in synaptic maturation during development. To evaluate this, we used a proteome-wide approach to characterize the synaptic proteome of Prmt8 knockout versus wild-type mice. Through comparative network-based analyses, proteins and functional clusters related to neurite development were identified to be differentially regulated between the two genotypes. One interesting protein that was differentially regulated was tenascin-R (TNR). Chromatin immunoprecipitation demonstrated binding of PRMT8 to the tenascin-r (Tnr) promoter. TNR, a component of perineuronal nets, preserves structural integrity of synaptic connections within neuronal networks during the development of visual-somatosensory cortices. On closer inspection, Prmt8 removal increased net formation and decreased inhibitory parvalbumin-positive (PV+) puncta on pyramidal neurons, thereby hindering the maturation of circuits. Consequently, visual acuity of the knockout mice was reduced. Our results demonstrated Prmt8's involvement in synaptic maturation and its prospect as an epigenetic modulator of developmental neuroplasticity by regulating structural elements such as the perineuronal nets.

DNA Methylation Targeting: The DNMT/HMT Crosstalk Challenge

Chromatin can adopt a decondensed state linked to gene transcription (euchromatin) and a condensed state linked to transcriptional repression (heterochromatin). These states are controlled by epigenetic modulators that are active on either the DNA or the histones and are tightly associated to each other. Methylation of both DNA and histones is involved in either the activation or silencing of genes and their crosstalk. Since DNA/histone methylation patterns are altered in cancers, molecules that target these modifications are interesting therapeutic tools. We present herein a vast panel of DNA methyltransferase inhibitors classified according to their mechanism, as well as selected histone methyltransferase inhibitors sharing a common mode of action.

Asymmetric Dimethylarginine and Its Relation As a Biomarker in Nephrologic Diseases

It is encouraging to observe that a search for publications on "asymmetric dimethylarginine (ADMA)" in PubMed, as updated on June 2016, yielded >2500 items, 24 years after a splendid paper published by Vallance et al in which the authors proposed that ADMA accumulation could be a cardiovascular risk factor in chronic kidney diseases. ADMA is the endogenous inhibitor of nitric oxide synthase and is related to endothelial dysfunction, which plays an important role in vascular damage elicited by various cardiometabolic risk factors. Although current knowledge suggests that ADMA has critical central roles in renal diseases, there are still unexplained details. The present article aims to provide a review on ADMA and its relation as a biomarker in nephrologic diseases. We aimed to systematize articles in which ADMA levels were assessed in order to clarify its role in many diseases and establish its reference values in different populations.

Construction of a series of pCS2+ backbone-based Gateway vectors for overexpressing various tagged proteins in vertebrates

Gateway vectors have been extensively developed to facilitate gene cloning in numerous species; however, a universal system that is compatible for multiple organisms was lacking. As a multipurpose expression vector, pCS2+ backbone-based expression plasmids are widely used for high-level expression of messenger RNAs (mRNAs) or proteins in mammalian/avian culture cells or Xenopus/zebrafish embryos. To date, a suite of vectors with pCS2+ backbone applicable for Gateway cloning system were unavailable yet. Here, we generated a set of Gateway destination vectors, named as pGCS (plasmids of Gateway in pCS2+) vectors, which can be fused to a choice of frequently used amino- or carboxyl-terminal tags, including MYC, HA, FLAG, His, GST, as well as eGFP fluorescent epitope. The systematic generation of this set of pCS2+ backbone-based Gateway destination vectors allows for in vitro recombination of DNA with high speed, accuracy, and reliability compared with the traditional 'digestion-ligation' cloning approach. Thus, our system accelerates the production of functional proteins, which could be widely expressed in a large variety of vertebrate organisms without tediously transferring genes into different expression vectors. Moreover, we make this series of Gateway vectors available to the research community via the non-profit Addgene Plasmid Repository.

Arginine Metabolism Revisited

Mammalian arginine metabolism is complex due to the expression of multiple enzymes that utilize arginine as substrate and to interactions or competition between specific enzymes involved in arginine metabolism. Moreover, cells may contain multiple intracellular arginine pools that are not equally accessible to all arginine metabolic enzymes, thus presenting additional challenges to more fully understanding arginine metabolism. At the whole-body level, arginine metabolism ultimately results in the production of a biochemically diverse range of products, including nitric oxide, urea, creatine, polyamines, proline, glutamate, agmatine, and homoarginine. Included in this group of compounds are the methylated arginines (e.g., asymmetric dimethylarginine), which are released upon degradation of proteins containing methylated arginine residues. Changes in arginine concentration also can regulate cellular metabolism and function via a variety of arginine sensors. Although much is known about arginine metabolism, elucidation of the physiologic or pathophysiologic roles for all of the pathways and their metabolites remains an active area of investigation, as exemplified by current findings highlighted in this review.

Pharmacological inhibition of arginine and lysine methyltransferases induces nuclear abnormalities and suppresses angiogenesis in human endothelial cells

Posttranslational modifications of histone tails can alter chromatin structure and regulate gene transcription. While recent studies implicate the lysine/arginine protein methyltransferases in the regulation of genes for endothelial metabolism, the role of AMI-1 and AMI-5 compounds in angiogenesis remains unknown. Here, we show that global inhibition of arginine and lysine histone methyltransferases (HMTs) by AMI-5 induced an angiostatic profile in human microvascular endothelial cells and human umbilical vein endothelial cells. Based on FACS analysis, we found that inhibition of HMTs significantly affects proliferation of endothelial cells, by suppressing cell cycle progression in the G₀/G₁ phase. Immunofluorescent studies of the endothelial cells replication pattern by 5-ethynyl-2'-deoxyuridine incorporation disclosed that AMI-5, and the arginine methyltransferase inhibitor AMI-1, induced heterochromatin formation and a number of nuclear abnormalities, such as formation of micronuclei (MNs) and nucleoplasmic bridges (NPBs), which are markers of chromosomal instability. In addition to the modification of the cell cycle machinery in response to AMIs treatment, also endothelial cells migration and capillary-like tube formation processes were significantly inhibited, implicating a stimulatory role of HMTs in angiogenesis.

From Genetics to Epigenetics: New Perspectives in Tourette Syndrome Research

Gilles de la Tourette Syndrome (TS) is a neurodevelopmental disorder marked by the appearance of multiple involuntary motor and vocal tics. TS presents high comorbidity rates with other disorders such as attention deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD). TS is highly heritable and has a complex polygenic background. However, environmental factors also play a role in the manifestation of symptoms. Different epigenetic mechanisms may represent the link between these two causalities. Epigenetic regulation has been shown to have an impact in the development of many neuropsychiatric disorders, however very little is known about its effects on Tourette Syndrome. This review provides a summary of the recent findings in genetic background of TS, followed by an overview on different epigenetic mechanisms, such as DNA methylation, histone modifications, and non-coding RNAs in the regulation of gene expression. Epigenetic studies in other neurological and psychiatric disorders are discussed along with the TS-related epigenetic findings available in the literature to date. Moreover, we are proposing that some general epigenetic mechanisms seen in other neuropsychiatric disorders may also play a role in the pathogenesis of TS.

Targeting epigenetic regulators for cancer therapy: modulation of bromodomain proteins, methyltransferases, demethylases, and microRNAs

INTRODUCTION

Histone deacetylases (HDACs) and DNA methyltransferases (DNMTs) were the first epigenetic targets to be successfully addressed for cancer treatment, but more recently additional families of epigenetic modulators have been the subject of intense research. Potent inhibitors have been identified in several instances and have proven to be invaluable tools for studying these proteins in normal physiology and in disease. Some have now progressed to clinical studies in hematological and solid tumors, and encouraging early results have been reported.

AREAS COVERED

This article reviews recent advances regarding the roles of new epigenetic players beyond HDACs and DNMTs in cancer, and discusses the impact of selective chemical probes on unravelling their function. The emerging field of non-coding RNAs (ncRNAs) and ongoing clinical studies with epigenetic drugs and microRNAs (miRNAs) are also addressed.

EXPERT OPINION

The roles of different epigenetic factors in numerous cancers have been unraveled recently, leading to the initiation of clinical studies. With inhibitors of BET bromodomain proteins, the histone methyltransferases EZH2 and DOT1L, and the histone demethylase LSD1 progressing through clinical trials, and the recognition of the importance of ncRNAs as potential biomarkers and therapeutics, this bears the hope that novel epigenetic therapies will be approved soon.

Subsets of Visceral Adipose Tissue Nuclei with Distinct Levels of 5-Hydroxymethylcytosine

The reprogramming of cellular memory in specific cell types, and in visceral adipocytes in particular, appears to be a fundamental aspect of obesity and its related negative health outcomes. We explored the hypothesis that adipose tissue contains epigenetically distinct subpopulations of adipocytes that are differentially potentiated to record cellular memories of their environment. Adipocytes are large, fragile, and technically difficult to efficiently isolate and fractionate. We developed fluorescence nuclear cytometry (FNC) and fluorescence activated nuclear sorting (FANS) of cellular nuclei from visceral adipose tissue (VAT) using the levels of the pan-adipocyte protein, peroxisome proliferator-activated receptor gamma-2 (PPARg2), to distinguish classes of PPARg2-Positive (PPARg2-Pos) adipocyte nuclei from PPARg2-Negative (PPARg2-Neg) leukocyte and endothelial cell nuclei. PPARg2-Pos nuclei were 10-fold enriched for most adipocyte marker transcripts relative to PPARg2-Neg nuclei. PPARg2-Pos nuclei showed 2- to 50-fold higher levels of transcripts encoding most of the chromatin-remodeling factors assayed, which regulate the methylation of histones and DNA cytosine (e.g., DNMT1, TET1, TET2, KDM4A, KMT2C, SETDB1, PAXIP1, ARID1A, JMJD6, CARM1, and PRMT5). PPARg2-Pos nuclei were large with decondensed chromatin. TAB-seq demonstrated 5-hydroxymethylcytosine (5hmC) levels were remarkably dynamic in gene bodies of various classes of VAT nuclei, dropping 3.8-fold from the highest quintile of expressed genes to the lowest. In short, VAT-derived adipocytes appear to be more actively remodeling their chromatin than non-adipocytes.

Histone H3K4 trimethylation: dynamic interplay with pre-mRNA splicing

Histone H3 lysine 4 trimethylation (H3K4me3) is often stated as a mark of transcriptionally active promoters. However, closer study of the positioning of H3K4me3 shows the mark locating primarily after the first exon at the 5′ splice site and overlapping with a CpG island in mammalian cells. There are several enzyme complexes that are involved in the placement of the H3K4me3 mark, including multiple protein complexes containing SETD1A, SETD1B, and MLL1 enzymes (writers). CXXC1, which is associated with SETD1A and SETD1B, target these enzymes to unmethylated CpG islands. Lysine demethylases (KDM5 family members, erasers) demethylate H3K4me3. The H3K4me3 mark is recognized by several proteins (readers), including lysine acetyltransferase complexes, chromatin remodelers, and RNA bound proteins involved in pre-mRNA splicing. Interestingly, attenuation of H3K4me3 impacts pre-mRNA splicing, and inhibition of pre-mRNA splicing attenuates H3K4me3.

Impact of Maternal Diet on the Epigenome during In Utero Life and the Developmental Programming of Diseases in Childhood and Adulthood

Exposure to environmental factors in early life can influence developmental processes and long-term health in humans. Early life nutrition and maternal diet are well-known examples of conditions shown to influence the risk of developing metabolic diseases, including type 2 diabetes mellitus and cardiovascular diseases, in adulthood. It is increasingly accepted that environmental compounds, including nutrients, can produce changes in the genome activity that, in spite of not altering the DNA sequence, can produce important, stable and, in some instances, transgenerational alterations in the phenotype. Epigenetics refers to changes in gene function that cannot be explained by changes in the DNA sequence, with DNA methylation patterns/histone modifications that can make important contributions to epigenetic memory. The epigenome can be considered as an interface between the genome and the environment that is central to the generation of phenotypes and their stability throughout the life course. To better understand the role of maternal health and nutrition in the initiation and progression of diseases in childhood and adulthood, it is necessary to identify the physiological and/or pathological roles of specific nutrients on the epigenome and how dietary interventions in utero and early life could modulate disease risk through epigenomic alteration.