Methylation Of Substrates Research Articles

Genetic and Physiological Probing of Cytoplasmic Bypasses for the Energy-Converting Methyltransferase Mtr in Methanosarcina acetivorans.

Methanogenesis is a unique energy metabolism carried out by members of the domain Archaea. Unlike most other methanogens, which reduce CO2 to methane with hydrogen as the electron donor, Methanosarcina acetivorans is able to grow on methylated compounds, on acetate, and on carbon monoxide (CO). These substrates are metabolized via distinct yet overlapping pathways. For the use of any single methanogenic substrate, the membrane-integral, energy-converting N5-methyl-tetrahydrosarcinapterin (H4SPT):coenzyme M (HS-CoM) methyltransferase (Mtr) is required. It was proposed that M. acetivorans can bypass the methyl transfer catalyzed by Mtr via cytoplasmic activities. To address this issue, conversion of different energy substrates by an mtr deletion mutant was analyzed. No significant methyl transfer from H4SPT to HS-CoM could be detected with CO as the electron donor. In contrast, formation of methane and CO2 in the presence of methanol or trimethylamine was indicative of an Mtr bypass in the oxidative direction. As methane thiol and dimethyl sulfide were transiently produced during methylotrophic methanogenesis in the mtr mutant, involvement in this process of methyl sulfide-dependent methyltransferases (Mts) was analyzed in a strain lacking both the Mts system and Mtr. It could be unequivocally demonstrated that the Mts system is not involved in bypassing Mtr, thereby ruling out previous proposals. Conversion of [13C]methanol indicated that in the absence of Mtr M. acetivorans provides the reducing equivalents for methyl-S-CoM reduction to methane by oxidizing (an) intracellular compound(s) to CO2 rather than disproportioning the source of methyl groups. Thus, no in vivo Mtr bypass appears to exist in M. acetivorans. IMPORTANCE Methanogenic archaea possess only a limited number of chemiosmotic coupling sites in their respiratory chains. Among them, N5-methyl-H4SPT:HS-CoM methyltransferase (Mtr) is the most widely distributed. Previous observations led to the conclusion that Methanosarcina acetivorans is able to bypass this reaction via methyl sulfide-dependent methyltransferases (Mts). However, strains lacking Mtr are not able to produce methane from CO. Also, these strains are unable to oxidize methylated substrates to CO2, in contrast to observations in the close relative Methanosarcina barkeri. The results also highlight the sole function of the Mts system in methyl sulfide metabolism. Thus, no in vivo Mtr bypass appears to exist in M. acetivorans.

Intrinsic catalytic properties of histone H3 lysine-9 methyltransferases preserve monomethylation levels under low S-adenosylmethionine

S-adenosylmethionine (SAM) is the methyl donor for site-specific methylation reactions on histone proteins, imparting key epigenetic information. During SAM-depleted conditions that can arise from dietary methionine restriction, lysine di- and tri-methylation are reduced while sites such as Histone-3 lysine-9 (H3K9) are actively maintained, allowing cells to restore higher-state methylation upon metabolic recovery. Here, we investigated if the intrinsic catalytic properties of H3K9 histone methyltransferases (HMTs) contribute to this epigenetic persistence. We employed systematic kinetic analyses and substrate binding assays using four recombinant H3K9 HMTs (i.e., EHMT1, EHMT2, SUV39H1, and SUV39H2). At both high and low (i.e., sub-saturating) SAM, all HMTs displayed the highest catalytic efficiency (kcat/KM) for monomethylation compared to di- and trimethylation on H3 peptide substrates. The favored monomethylation reaction was also reflected in kcat values, apart from SUV39H2 which displayed a similar kcat regardless of substrate methylation state. Using differentially methylated nucleosomes as substrates, kinetic analyses of EHMT1 and EHMT2 revealed similar catalytic preferences. Orthogonal binding assays revealed only small differences in substrate affinity across methylation states, suggesting that catalytic steps dictate the monomethylation preferences of EHMT1, EHMT2, and SUV39H1. To link invitro catalytic rates with nuclear methylation dynamics, we built a mathematical model incorporating measured kinetic parameters and a time course of mass spectrometry-based H3K9 methylation measurements following cellular SAM depletion. The model revealed that the intrinsic kinetic constants of the catalytic domains could recapitulate invivo observations. Together, these results suggest catalytic discrimination by H3K9 HMTs maintains nuclear H3K9me1, ensuring epigenetic persistence after metabolic stress.

γ-enolase (ENO2) is methylated at the Nτ position of His-190 among enolase isozymes.

Protein methylation is mainly observed in lysine, arginine and histidine residues. Histidine methylation occurs at one of two different nitrogen atoms of the imidazole ring, producing Nτ-methylhistidine and Nπ-methylhistidine, and it has recently attracted attention with the identification of SETD3, METTL18 and METTL9 as catalytic enzymes in mammals. Although accumulating evidence had suggested the presence of more than 100 proteins containing methylated histidine residues in cells, much less information has been known regarding histidine-methylated proteins than lysine- and arginine-methylated ones, because no method has been developed to identify substrates for histidine methylation. Here, we established a method to screen novel target proteins for histidine methylation, using biochemical protein fractionation combined with the quantification of methylhistidine by LC-MS/MS. Interestingly, the differential distribution pattern of Nτ-methylated proteins was found between the brain and skeletal muscle, and identified γ-enolase where the His-190 at the Nτ position is methylated in mouse brain. Finally, in silico structural prediction and biochemical analysis showed that the His-190 in γ-enolase is involved in the intermolecular homodimeric formation and enzymatic activity. In the present study, we provide a new methodology to find histidine-methylated proteins in vivo and suggest an insight into the importance of histidine methylation.

KO MAT2A to further inhibit hypomorphic PRMT5 in MATPdeficient TNBC cells for metastasis suppression in vitro and in vivo

Triple-negative breast cancer is one of the common types with the lack of three joint receptors, ER, PR, and HER2, which leads to inadequate responses for current breast cancer targeting therapy. Previous studies have reported that MTAP deletion confers enhanced sensitivity for PRMT5 inhibition, and inhibition of PRMT5 suppresses cell growth by decreasing arginine methylation of eIF4E and FGFR3. The KO of MAT2A will reduce the level of SAM, which is the substrate for arginine methylation, to inhibit PRMT5 and reduce cell proliferation. This study investigates the comparison of effects for MAT2A KO in MATP-deficient and MTAP+/+ TNBC cells in vivo and in vitro..

Early pregnancy associated changes in systemic lipid profiles of mares revealed by high resolution mass spectrometry

Early pregnancy in the mare presents a risk of embryo loss, with little known of the systemic lipid dynamics that contribute to a successful or failed pregnancy. Observations in horses and other species suggest that pregnancy is characterized by an anabolic (i.e. fat deposition) lipid profile initially, followed by a catabolic (lipid mobilization) profile toward the end of gestation. There have been no investigations of lipid metabolism in the very early stages of pregnancy, leading up to and during the time of maternal recognition. High resolution lipidomics presents an unprecedented opportunity to map the changes in lipid profiles of pregnant mares, to examine metabolic pathways contributing to establishment of pregnancy and to identify biomarkers for detection and monitoring of early pregnancy and pregnancy loss. Blood samples were collected from Thoroughbred mares in a commercial breeding operation at day 7 and day 14 following ovulation. Mares were live-covered, and pregnancy tested by transrectal ultrasound at day 14, hereby designated pregnant or non-pregnant. High resolution lipidomics analysis was performed on isolated plasma to compare profiles of pregnant (7P, 14P) and non-pregnant (7NP, 14NP) mares at day 7 and day 14 (total n = 72, split evenly in groups). Lipids were extracted using ice-cold butanol/methanol (1:1 v/v) with 10 mM ammonium acetate containing internal standards.LC separation was performed on a Phenomenex Kinetex C18 Column (2.6 µm, 100 Å, 100 × 2.1 mm) using 5 µL injection volume. The samples were analyzed in data dependent mode using Zeno EAD IDA on the ZenoTOF 7600 system. All data were analyzed using MS-DIAL 5.1. The analysis yielded a total of 10034 unique lipid species across all samples. A total of 277 and 1722 lipids were significantly altered (p<0.05) in pregnant vs non-pregnant animals at day 7 and day 14, respectively. Phosphatidylcholines (PC) were significantly increased in 7P vs 7NP, and phosphatidylethanolamines (PE) were significantly decreased in 7P vs 7NP, with similar trends observed at day 14. Lysophosphatidylcholines (LPC) were increased in 14P vs 14NP. PC and LPC concentrations also increased from day 7 to day 14, but only in pregnant animals. Collectively, these observations point to a major role for phospholipid metabolism in early pregnancy and are consistent with PE being a substrate for methylation to PC, which is a key source of choline crucial for early embryonic development. The roles of PC biosynthesis and supplementation in early equine pregnancy warrant further investigation. Furthermore, alterations in the lipid profile of mares at day 7 post-ovulation challenge the current paradigm that no systemic changes occur in the pregnant mare prior to classical maternal recognition and luteal maintenance.

Effectors and effects of arginine methylation.

Arginine methylation is a ubiquitous and relatively stable post-translational modification (PTM) that occurs in three types: monomethylarginine (MMA), asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). Methylarginine marks are catalyzed by members of the protein arginine methyltransferases (PRMTs) family of enzymes. Substrates for arginine methylation are found in most cellular compartments, with RNA-binding proteins forming the majority of PRMT targets. Arginine methylation often occurs in intrinsically disordered regions of proteins, which impacts biological processes like protein-protein interactions and phase separation, to modulate gene transcription, mRNA splicing and signal transduction. With regards to protein-protein interactions, the major 'readers' of methylarginine marks are Tudor domain-containing proteins, although additional domain types and unique protein folds have also recently been identified as methylarginine readers. Here, we will assess the current 'state-of-the-art' in the arginine methylation reader field. We will focus on the biological functions of the Tudor domain-containing methylarginine readers and address other domains and complexes that sense methylarginine marks.

Martin Silicates as Partners in Photoredox/Ni Dual Catalysis for the Installation of CH3, CH2D, CD2H, CD3and13CH3Groups onto (Hetero)Arenes

Martin Silicates as Partners in Photoredox/Ni Dual Catalysis for the Installation of CH₃, CH₂D, CD₂H, CD₃and¹³CH₃Groups onto (Hetero)Arenes

Epigenetic potential: Promoter CpG content positively covaries with lifespan and is dependent on gene function among vertebrates.

Variation in DNA methylation is associated with many ecological and life history traits, including niche breadth and lifespan. In vertebrates, DNA methylation occurs almost exclusively at "CpG" dinucleotides. Yet, how variation in the CpG content of the genome impacts organismal ecology has been largely overlooked. Here, we explore associations between promoter CpG content, lifespan and niche breadth among 60, amniote vertebrate species. The CpG content of 16 functionally relevant gene promoters was strongly, positively associated with lifespan in mammals and reptiles, but was not related to niche breadth. Possibly, by providing more substrate for CpG methylation to occur, high promoter CpG content extends the time taken for deleterious, age-related errors in CpG methylation patterns to accumulate, thereby extending lifespan. The association between CpG content and lifespan was driven by gene promoters with intermediate CpG enrichment-those known to be predisposed to regulation by methylation. Our findings provide novel support for the idea that high CpG content has been selected for in long-lived species to preserve the capacity for gene expression regulation by CpG methylation. Intriguingly, promoter CpG content was also dependent on gene function in our study; immune genes had on average 20% less CpG sites than metabolic- and stress-related genes.

Optimizing purification and activity assays of N-terminal methyltransferase complexes.

In vitro methyltransferase assays have traditionally been carried out with tritiated S-adenosyl-methionine (SAM) as the methyl donor, as site-specific methylation antibodies are not always available for Western or dot blots and structural requirements of many methyltransferases prohibit the use of peptide substrates in luminescent or colorimetric assays. The discovery of the first N-terminal methyltransferase, METTL11A, has allowed for a second look at non-radioactive in vitro methyltransferase assays, as N-terminal methylation is amenable to antibody production and the limited structural requirements of METTL11A allow for its methylation of peptide substrates. We have used a combination of Western blots and luminescent assays to verify substrates of METTL11A and the two other known N-terminal methyltransferases, METTL11B and METTL13. We have also developed these assays for use beyond substrate identification, showing that METTL11A activity is opposingly regulated by METTL11B and METTL13. Here we provide two methods for non-radioactive characterization of N-terminal methylation, Western blots with full-length recombinant protein substrates and luminescent assays with peptide substrates, and describe how each can be additionally adapted to look at regulatory complexes. We will review the advantages and disadvantages of each method in context with the other types of in vitro methyltransferase assays and discuss why these types of assays could be of general use to the N-terminal modification field.

Chicken PRMT1 promotes infectious bursal disease virus replication via suppressing IFN-β production

The protein arginine methyltransferase (PRMT) family, such as PRMT1, regulates the arginine methylation of various substrates. Many studies have examined the role of PRMT1 in mammals, however, it is still unknown how PRMT1 works in chickens. To investigate the effect of chicken PRMT1 (chPRMT1) on regulating IFN-β production and IBDV replication, chPRMT1 knock out DF-1 cells were constructed in this study. First, we found that chPRMT1 was widely expressed in a variety of chicken tissues and that it was distributed in the cytoplasm and nucleus of DF-1 cells. Additionally, IFN-β activation was inhibited by chPRMT1 at the step of chMAVS. In addition, chPRMT1 knock out DF-1 cells were constructed using CRISPR-Cas9 technique. The morphology and viability of chPRMT1 knock out DF-1 cells were similar with the wild-type cells. In addition, the IFN-β as well as interferon stimulate genes activation induced by chMAVS in PRMT1 knock out DF-1 cells were significantly higher than that in WT cells. Furthermore, ectopic expression of chPRMT1 significantly supports IBDV replication. We also found that the ability of IBDV replication in PRMT1 knock out DF-1 cells was remarkably lower than that of in WT cells, suggesting that PRMT1 negatively regulate IBDV replication via suppressing IFN-β production. In conclusion, the PRMT1 knock out DF-1 cells were constructed, which was further used to demonstrate an inhibitory role of chPRMT1 in IFN-β production, and a contributor of chPRMT1 in IBDV replication.

Structure-activity relationship study of a series of nucleoside derivatives bearing sulfonamide scaffold as potent and selective PRMT5 inhibitors

Protein arginine methyltransferase 5 (PRMT5) is a promising target for the treatment of malignant tumors. The discovery of nucleoside-derived inhibitors against PRMT5 with novel scaffold has been challenging. Herein, we report our effort on the design and synthesis of nucleoside derivatives bearing sulfonamide scaffold as potent PRMT5 inhibitors. The representative compound 23n was identified as a potent and selective PRMT5 inhibitor with an IC50 value of 8 nM. Molecular docking study demonstrated the binding mode of compound 23n and illustrated its inhibitory activity to PRMT5. The Trimethyl Lock prodrug strategy was used to afford prodrug 36 with lower polarity which could rapidly release the active compound 23n after entering the tumor cells. Cell-based assays revealed that the prodrug 36 restrained the proliferation of Z-138 and MOLM-13 cells and suppressed methylation of PRMT5 substrate more potently than 23n. Additionally, both compound 23n and 36 exerted antiproliferative effects against Z-138 cells mainly by inducing apoptosis effectively rather than arresting cell cycle. Thus, compounds 23n and 36 represent a series of potent PRMT5 inhibitor with novel scaffold.

Enantioselective hydromethylation of unfunctionalized olefins with copper-hydride catalysis

Recently in the Journal of the American Chemical Society , Buchwald and co-workers achieved enantioselective installation of a methyl group through copper-catalyzed hydromethylation. They demonstrated the utility of this method through the methylation of several olefin substrates, including drug molecules. Recently in the Journal of the American Chemical Society , Buchwald and co-workers achieved enantioselective installation of a methyl group through copper-catalyzed hydromethylation. They demonstrated the utility of this method through the methylation of several olefin substrates, including drug molecules.

Epigenetic Regulation by microRNAs in Hyperhomocysteinemia-Accelerated Atherosclerosis.

Increased serum levels of homocysteine (Hcy) is a risk factor for cardiovascular disease and is specifically linked to various diseases of the vasculature such as atherosclerosis. However, the precise mechanisms by which Hcy contributes to this condition remain elusive. During the development of atherosclerosis, epigenetic modifications influence gene expression. As such, epigenetic modifications are an adaptive response to endogenous and exogenous factors that lead to altered gene expression by methylation and acetylation reactions of different substrates and the action of noncoding RNA including microRNAs (miRNAs). Epigenetic remodeling modulates cell biology in both physiological and physiopathological conditions. DNA and histone modification have been identified to have a crucial role in the progression of atherosclerosis. However, the potential role of miRNAs in hyperHcy (HHcy)-related atherosclerosis disease remains poorly explored and might be essential as well. There is no review available yet summarizing the contribution of miRNAs to hyperhomocystein-mediated atherogenicity or their potential as therapeutic targets even though their important role has been described in numerous studies. Specifically, downregulation of miR-143 or miR-125b has been shown to regulate VSCMs proliferation in vitro. In preclinical studies, downregulation of miR-92 or miR195-3p has been shown to increase the accumulation of cholesterol in foam cells and increase macrophage inflammation and atherosclerotic plaque formation, respectively. Another preclinical study found that there is a reciprocal regulation between miR-148a/152 and DNMT1 in Hcy-accelerated atherosclerosis. Interestingly, a couple of studies have shown that miR-143 or miR-217 may be used as potential biomarkers in patients with HHcy that may develop atherosclerosis. Moreover, the current review will also update current knowledge on miRNA-based therapies, their challenges, and approaches to deal with Hcy-induced atherosclerosis.

Discovery and Biological Characterization of PRMT5:MEP50 Protein-Protein Interaction Inhibitors.

Protein arginine methyltransferase 5 (PRMT5) is a master epigenetic regulator and an extensively validated therapeutic target in multiple cancers. Notably, PRMT5 is the only PRMT that requires an obligate cofactor, methylosome protein 50 (MEP50), to function. We developed compound 17, a novel small-molecule PRMT5:MEP50 protein-protein interaction (PPI) inhibitor, after initial virtual screen hit identification and analogue refinement. Molecular docking indicated that compound 17 targets PRMT5:MEP50 PPI by displacing the MEP50 W54 burial into a hydrophobic pocket of the PRMT5 TIM barrel. In vitro analysis indicates IC50 < 500 nM for prostate and lung cancer cells with selective, specific inhibition of PRMT5:MEP50 substrate methylation and target gene expression, and RNA-seq analysis suggests that compound 17 may dysregulate TGF-β signaling. Compound 17 provides a proof of concept in targeting PRMT5:MEP50 PPI, as opposed to catalytic targeting, as a novel mechanism of action and supports further preclinical development of inhibitors in this class.

Impact of G-Quadruplex Structures on Methylation of Model Substrates by DNA Methyltransferase Dnmt3a.

In mammals, de novo methylation of cytosines in DNA CpG sites is performed by DNA methyltransferase Dnmt3a. Changes in the methylation status of CpG islands are critical for gene regulation and for the progression of some cancers. Recently, the potential involvement of DNA G-quadruplexes (G4s) in methylation control has been found. Here, we provide evidence for a link between G4 formation and the function of murine DNA methyltransferase Dnmt3a and its individual domains. As DNA models, we used (i) an isolated G4 formed by oligonucleotide capable of folding into parallel quadruplex and (ii) the same G4 inserted into a double-stranded DNA bearing several CpG sites. Using electrophoretic mobility shift and fluorescence polarization assays, we showed that the Dnmt3a catalytic domain (Dnmt3a-CD), in contrast to regulatory PWWP domain, effectively binds the G4 structure formed in both DNA models. The G4-forming oligonucleotide displaced the DNA substrate from its complex with Dnmt3a-CD, resulting in a dramatic suppression of the enzyme activity. In addition, a direct impact of G4 inserted into the DNA duplex on the methylation of a specific CpG site was revealed. Possible mechanisms of G4-mediated epigenetic regulation may include Dnmt3a sequestration at G4 and/or disruption of Dnmt3a oligomerization on the DNA surface.

DNA methyltransferase DNMT3A forms interaction networks with the CpG site and flanking sequence elements for efficient methylation

Specific DNA methylation at CpG and non-CpG sites is essential for chromatin regulation. The DNA methyltransferase DNMT3A interacts with target sites surrounded by variable DNA sequences with its TRD and RD loops, but the functional necessity of these interactions is unclear. We investigated CpG and non-CpG methylation in a randomized sequence context using WT DNMT3A and several DNMT3A variants containing mutations at DNA-interacting residues. Our data revealed that the flanking sequence of target sites between the −2 and up to the +8 position modulates methylation rates >100-fold. Non-CpG methylation flanking preferences were even stronger and favor C(+1). R836 and N838 in concert mediate recognition of the CpG guanine. R836 changes its conformation in a flanking sequence-dependent manner and either contacts the CpG guanine or the +1/+2 flank, thereby coupling the interaction with both sequence elements. R836 suppresses activity at CNT sites but supports methylation of CAC substrates, the preferred target for non-CpG methylation of DNMT3A in cells. N838 helps to balance this effect and prevent the preference for C(+1) from becoming too strong. Surprisingly, we found L883 reduces DNMT3A activity despite being highly conserved in evolution. However, mutations at L883 disrupt the DNMT3A-specific DNA interactions of the RD loop, leading to altered flanking sequence preferences. Similar effects occur after the R882H mutation in cancer cells. Our data reveal that DNMT3A forms flexible and interdependent interaction networks with the CpG guanine and flanking residues that ensure recognition of the CpG and efficient methylation of the cytosine in contexts of variable flanking sequences.

Determination of dimethyl sulfate genotoxic impurities in tertiary amine drugs by ultra-high performance liquid chromatography-tandem mass spectrometry

硫酸二甲酯被广泛用于药品的有机合成中,具有很强的毒性及腐蚀性,因此应严格控制其在药品中的残留量。现有传统检测方法在样品制备过程中不允许使用水,且存在专属性低、灵敏度差等缺陷,严重制约了检测方法的通用性和准确度。研究采用超高效液相色谱-串联质谱技术(UHPLC-MS/MS),建立了氨基比林等叔胺类药品中残留的硫酸二甲酯的测定方法。检测方法以氨基比林作为衍生剂,40 ℃条件下氨基比林和硫酸二甲酯在水溶液中能够快速反应生成甲基化氨基比林,通过检测甲基化氨基比林间接计算硫酸二甲酯的残留含量。采用Waters Atlantis HILIC C18色谱柱(100 mm×2.1 mm, 3.0 μm),以10 mmol/L乙酸铵水溶液-0.1%甲酸甲醇溶液(50∶50, v/v)为流动相进行等度洗脱,流速0.3 mL/min,柱温40 ℃,进样量1 μL;在电喷雾电离、正离子(ESI+)多反应监测(MRM)模式下测定硫酸二甲酯的含量。硫酸二甲酯在0.9935~7.9480 ng/mL范围内线性关系良好,相关系数(r)为0.9997,方法的检出限为0.50 ng/mL,定量限为1.15 ng/mL,加标回收率为94.9%~106.4%。建立的检测方法用于氨基比林、咖啡因、替加氟等9批样品中,均未检出硫酸二甲酯,说明各药品生产企业注重了该基因毒杂质残留量的控制。该方法专属性强,灵敏度高,操作简单,定量准确,适用于氨基比林等药品中硫酸二甲酯基因毒杂质的测定。

492TiP A phase I study of synthetic lethal, IDE397 (MAT2A inhibitor) as a monotherapy and in combination with chemotherapy in advanced solid tumors harboring MTAP deletion

Methylthioadenosine phosphorylase (MTAP) deletion occurs in ∼15% of solid tumors in the setting of 9p21 loss and is associated with poor survival (Nature Communications; 2021; 12:5606; Han G). Loss of MTAP results in methylthioadenosine (MTA) accumulation and partial inhibition of protein arginine methyltransferase-5 (PRMT5). Inhibition of methionine adenosyltransferase-2a (MAT2A) results in reduction of s-adenosyl methionine (SAM), starving PRMT5 of its methylation substrate with resulting selective sensitivity of MTAP null cancer cells. IDE397 is a novel MAT2A inhibitor being evaluated in cancer patients harboring a tumor having MTAP deletion. IDE397 has superior cellular potency, selectivity, and drug properties, including lack of liver toxicity signals and high solubility, compared to the other MAT2A inhibitors under clinical investigation. In preclinical models, including patient derived xenografts, IDE397 has been shown to exploit the synthetic lethal relationship between MTAP deletion and MAT2A with broad activity and regressions of tumors with MTAP loss as a single agent and in combination with taxanes and other chemotherapy agents across multiple solid tumor indications. Preclinically, IDE397 shows robust pharmacodynamic modulation of SAM and symmetric dimethylarginine (SDMA). (IDEAYA Data). Study IDE397-001 (NCT04794699), is a phase I, muticenter, open-label study of IDE397 as a single agent in adult participants with advanced solid tumors harboring MTAP deletion. Additional escalation, expansion and combination arms with taxanes and other agents are planned across multiple indications (NSCLC, esophagogastric and other solid tumors). All participants will receive oral daily dosing of IDE397, as monotherapy or in combination with chemotherapy, until disease progression, unacceptable toxicity, or other withdrawal criteria are met. Primary endpoints include safety and tolerability, RP2D determination, investigator-assessed tumor response by RECIST v1.1. Enrollment in the monotherapy dose escalation is ongoing with clearance of the first 5 dose levels without DLT. NCT04794699. IDEAYA Biosciences, Inc.

NF90/NFAR (nuclear factors associated with dsRNA)- a new methylation substrate of the PRMT5-WD45-RioK1 complex.

Protein-arginine methylation is a common posttranslational modification, crucial to various cellular processes, such as protein-protein interactions or binding to nucleic acids. The central enzyme of symmetric protein arginine methylation in mammals is the protein arginine methyltransferase 5 (PRMT5). While the methylation reaction itself is well understood, recruitment and differentiation among substrates remain less clear. One mechanism to regulate the diversity of PRMT5 substrate recognition is the mutual binding to the adaptor proteins pICln or RioK1. Here, we describe the specific interaction of Nuclear Factor 90 (NF90) with the PRMT5-WD45-RioK1 complex. We show for the first time that NF90 is symmetrically dimethylated by PRMT5 within the RG-rich region in its C-terminus. Since upregulation of PRMT5 is a hallmark of many cancer cells, the characterization of its dimethylation and modulation by specific commercial inhibitors in vivo presented here may contribute to a better understanding of PRMT5 function and its role in cancer.

An Epigenetic Role of Mitochondria in Cancer.

Mitochondria are not only the main energy supplier but are also the cell metabolic center regulating multiple key metaborates that play pivotal roles in epigenetics regulation. These metabolites include acetyl-CoA, α-ketoglutarate (α-KG), S-adenosyl methionine (SAM), NAD+, and O-linked beta-N-acetylglucosamine (O-GlcNAc), which are the main substrates for DNA methylation and histone post-translation modifications, essential for gene transcriptional regulation and cell fate determination. Tumorigenesis is attributed to many factors, including gene mutations and tumor microenvironment. Mitochondria and epigenetics play essential roles in tumor initiation, evolution, metastasis, and recurrence. Targeting mitochondrial metabolism and epigenetics are promising therapeutic strategies for tumor treatment. In this review, we summarize the roles of mitochondria in key metabolites required for epigenetics modification and in cell fate regulation and discuss the current strategy in cancer therapies via targeting epigenetic modifiers and related enzymes in metabolic regulation. This review is an important contribution to the understanding of the current metabolic-epigenetic-tumorigenesis concept.