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Dipeptide repeat proteins (DPRs) are aberrant protein species found in C9orf72-linked amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two neurodegenerative diseases characterized by the cytoplasmic mislocalization and aggregation of RNA-binding proteins (RBPs). In particular, arginine (R)-rich DPRs (poly-GR and poly-PR) have been suggested to promiscuously interact with multiple cellular proteins and thereby exert high cytotoxicity. Components of the protein arginine methylation machinery have been identified as modulators of DPR toxicity and/or potential cellular interactors of R-rich DPRs; however, the molecular details and consequences of such an interaction are currently not well understood. Here, we demonstrate that several members of the family of protein arginine methyltransferases (PRMTs) can directly interact with R-rich DPRs in vitro and in the cytosol. In vitro, R-rich DPRs reduce solubility and promote phase separation of PRMT1, the main enzyme responsible for asymmetric arginine-dimethylation (ADMA) in mammalian cells, in a concentration- and length-dependent manner. Moreover, we demonstrate that poly-GR interferes more efficiently than poly-PR with PRMT1-mediated arginine methylation of RBPs such as hnRNPA3. We additionally show by two alternative approaches that poly-GR itself is a substrate for PRMT1-mediated arginine dimethylation. We propose that poly-GR may act as a direct competitor for arginine methylation of cellular PRMT1 targets, such as disease-linked RBPs.

Protein arginine methyltransferase (PRMT) 4 (also known as coactivator-associated arginine methyltransferase 1; CARM1) is involved in a variety of biological processes and is considered as an emerging target class in oncology and other diseases. A successful strategy to identify PRMT substrate-competitive inhibitors has been to exploit chemical scaffolds able to mimic the arginine substrate. (S)-Alanine amide moiety is a valuable arginine mimic for the development of potent and selective PRMT4 inhibitors; however, its high hydrophilicity led to derivatives with poor cellular outcomes. Here, we describe the development of PRMT4 inhibitors featuring a central pyrrole core and an alanine amide moiety. Rounds of optimization, aimed to increase lipophilicity and simultaneously preserve the inhibitory activity, produced derivatives that, despite good potency and physicochemical properties, did not achieve on-target effects in cells. On the other hand, masking the amino group with a NAD(P)H:quinone oxidoreductase 1 (NQO1)-responsive trigger group, led to prodrugs able to reduce arginine dimethylation of the PRMT4 substrates BRG1-associated factor 155 (BAF155). These results indicate that prodrug strategies can be successfully applied to alanine-amide containing PRMT4 inhibitors and provide an option to enable such compounds to achieve sufficiently high exposures in vivo., (© 2024 The Authors. ChemMedChem published by Wiley-VCH GmbH.)

Protein arginine methyltransferases (PRMTs) in mammals play a role in various signaling pathways, such as virus infection, inflammasome responses, and cancer growth. While some PRMTs have been found to regulate interferon production in mammals, the mechanism in chickens remains to be fully understood. This study focused on investigating the function of chicken PRMTs. Our findings indicate that chicken PRMTs act as inhibitors of interferon production in response to dsRNA or MDA5 stimulation. Each PRMT is involved in different stages of interferon induction through the MDA5-MAVS-TBK1 pathway. Furthermore, we observed the colocalization of multiple PRMTs with the viral protein VP3 of infectious bursal disease virus (IBDV). Among the chicken PRMTs studied, PRMT3 was found to be widely expressed in various organs and its expression was upregulated during IBDV infection. Notably, PRMT3 supported IBDV replication, as demonstrated by ectopic expression and inhibition studies using SGC-707. Silencing of PRMT3 led to enhanced interferon production and inhibition of IBDV replication. This study provides novel insights into the role of chicken PRMTs, particularly PRMT3, in promoting IBDV replication by suppressing interferon signaling., Competing Interests: DISCLOSURES The authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Obesity has become a major global problem that significantly confers an increased risk of developing life-threatening complications, including type 2 diabetes mellitus, fatty liver disease and cardiovascular diseases. Protein arginine methyltransferases (PRMTs) are enzymes that catalyse the methylation of target proteins. They are ubiquitous in eukaryotes and regulate transcription, splicing, cell metabolism and RNA biology. As a key, epigenetically modified enzyme, protein arginine methyltransferase 1 (PRMT1) is involved in obesity-related metabolic processes, such as lipid metabolism, the insulin signalling pathway, energy balance and inflammation, and plays an important role in the pathology of obesity-related metabolic disorders. This review summarizes recent research on the role of PRMT1 in obesity-related metabolic disorders. The primary objective was to comprehensively elucidate the functional role and regulatory mechanisms of PRMT1. Moreover, this study attempts to review the pathogenesis of PRMT1-mediated obesity-related metabolic disorders, thereby offering pivotal information for further studies and clinical treatment., (© 2024 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.)

Mutations in the master hematopoietic transcription factor GATA1 are often associated with functional defects in erythropoiesis and megakaryopoiesis. In this study, we identified a novel GATA1 germline mutation (c.1162delGG, p.Leu387Leufs*62) in a patient with congenital anemia and occasional thrombocytopenia. The C-terminal GATA1, a rarely studied mutational region, undergoes frameshifting translation as a consequence of this double-base deletion mutation. To investigate the specific function and pathogenic mechanism of this mutant, in vitro mutant models of stable re-expression cells were generated. The mutation was subsequently validated to cause diminished transcriptional activity of GATA1 and defective differentiation of erythroid and megakaryocytes. Using proximity labeling and mass spectrometry, we identified selective alterations in the proximal protein networks of the mutant, revealing decreased binding to a set of normal GATA1-interaction proteins, including the essential co-factor FOG1. Notably, our findings further demonstrated enhanced recruitment of the protein arginine methyltransferase PRMT6, which mediates histone modification at H3R2me2a and represses transcription activity. We also found an enhanced binding of this mutant GATA1/PRMT6 complex to the transcriptional regulatory elements of GATA1's target genes. Moreover, treatment of the PRMT6 inhibitor MS023 could partially rescue the inhibited transcriptional and impaired erythroid differentiation caused by the GATA1 mutation. Taken together, our results provide molecular insights into erythropoiesis in which mutation leads to partial loss of GATA1 function, and the role of PRMT6 and its inhibitor MS023 in congenital anemia, highlighting PRMT6 binding as a negative factor of GATA1 transcriptional activity in aberrant hematopoiesis.

Objectives: To explore the effect of protein arginine methyltransferase 5 (PRMT5) on tooth extraction sockets healing, we established an extraction sockets model in osteoblast-conditional Prmt5 knockout mice. The results provided clues for promoting extraction sockets healing in clinical settings., Materials and Methods: Maxillary first molars were extracted from 6 to 8-week-old mice to establish an extraction fossa model. Microcomputed tomography (Micro-CT), histology, and immunostaining assays were performed on samples harvested at 3-, 7-, and 14-day post-extraction. Prmt5-silenced cell lines  were employed to explore the regulatory mechanisms underlying the osteigenic differentiation., Results: PRMT5 expression was higher in the early stage of socket healing. Micro-CT analysis showed that the percentage of new bone in the extraction sockets was lower in OC-Cre; Prmt5 fl/fl mice than in the control group, consistent with Masson staining. We found that, Prmt5 deficiency delayed the osteogenesis during extraction socket healing, which might be achieved through the decrease of H4R3me2s in the Sp7 promoter region., Conclusion: PRMT5 in osteoblasts may promote the differentiation of osteoblasts by regulating the Sp7 promoter H4R3me2s and participate in the healing of tooth extraction sockets., (© 2024 Wiley Periodicals LLC.)

PRMT5, a type 2 arginine methyltransferase, has a critical role in regulating cell growth and survival in cancer. With the aim of developing MTA-cooperative PRMT5 inhibitors suitable for MTAP-deficient cancers, herein we report our efforts to develop novel "MTA-cooperative" compounds identified through a high-throughput biochemical screening approach. Optimization of hits was achieved through structure-based design with a focus on improvement of oral drug-like properties. Bioisosteric replacement of the original thiazole guanidine headgroup, spirocyclization of the isoindolinone amide scaffold to both configurationally and conformationally lock the bioactive form, and fine-tuning of the potency, MTA cooperativity, and DMPK properties through specific substitutions of the azaindole headgroup were conducted. We have identified an orally available in vivo lead compound, 28 ("AZ-PRMT5i-1"), which shows sub-10 nM PRMT5 cell potency, >50-fold MTA cooperativity, suitable DMPK properties for oral dosing, and significant PRMT5-driven in vivo efficacy in several MTAP-deficient preclinical cancer models.

Targeting the protein arginine methyltransferase 1 (PRMT1) has emerged as a promising therapeutic strategy in cancer treatment. The phase 1 clinical trial for GSK3368715, the first PRMT1 inhibitor to enter the clinic, was terminated early due to a lack of clinical efficacy, extensive treatment-emergent effects, and dose-limiting toxicities. The incidence of the latter two events may be associated with inhibition-driven pharmacology as a high and sustained concentration of inhibitor is required for therapeutic effect. The degradation of PRMT1 using a proteolysis targeting chimera (PROTAC) may be superior to inhibition as proceeds via event-driven pharmacology where a PROTAC acts catalytically at a low dose. PROTACs containing the same pharmacophore as GSK3368715, combined with a motif that recruits the VHL or CRBN E3-ligase, were synthesised. Suitable cell permeability and target engagement were shown for selected candidates by the detection of downstream effects of PRMT1 inhibition and by a NanoBRET assay for E3-ligase binding, however the candidates did not induce PRMT1 degradation. This paper is the first reported investigation of PRMT1 for targeted protein degradation and provides hypotheses and insights to assist the design of PROTACs for PRMT1 and other novel target proteins., (© 2024 The Authors. ChemMedChem published by Wiley-VCH GmbH.)

Corneal neovascularization (CoNV) is predominantly initiated by inflammatory processes, resulting in aberrant vascular proliferation and consequent visual impairment. Existing therapeutic interventions for CoNV demonstrate limited efficacy and potential for adverse reactions. Protein arginine methyltransferase 1 (PRMT1) is associated with the regulation of inflammation and M2 macrophage polarization. Nevertheless, the precise mechanism by which PRMT1 operates in CoNV remains uncertain. This study explored the impact of PRMT1 inhibition in a murine model of CoNV induced by alkali burn. Our findings indicated a direct relationship between PRMT1 levels and corneal damage. Moreover, our observations indicated an increase in fibroblast growth factor 2 (FGF2) expression in CoNV, which was reduced after treatment with a PRMT1 inhibitor. The inhibition of PRMT1 alleviated both corneal injury and CoNV, as evidenced by decreased corneal opacity and neovascularization. Immunofluorescence analysis and evaluation of inflammatory factor expression demonstrated that PRMT1 inhibition attenuated M2 macrophage polarization, a phenomenon that was reversed by the administration of recombinant FGF2 protein. These results were confirmed through experimentation on Human Umbilical Vein Endothelial Cells (HUVECs) and Mouse leukemia cells of monocyte macrophage cells (RAW264.7). Furthermore, it was established that FGF2 played a role in PI3K/Akt signal transduction, a critical regulatory pathway for M2 macrophage polarization. Importantly, the activity of this pathway was found to be suppressed by PRMT1 inhibitors. Mechanistically, PRMT1 was shown to promote M2 macrophage polarization, thereby contributing to CoNV, through the FGF2/PI3K/Akt pathway. Therefore, targeting PRMT1 may offer a promising therapeutic approach., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Breast cancer is the most common cancer diagnosed in women worldwide. Early-stage breast cancer is curable in ~70-80% of patients, while advanced metastatic breast cancer is considered incurable with current therapies. Breast cancer is a highly heterogeneous disease categorized into three main subtypes based on key markers orientating specific treatment strategies for each subtype. The complexity of breast carcinogenesis is often associated with epigenetic modification regulating different signaling pathways, involved in breast tumor initiation and progression, particularly by the methylation of arginine residues. Protein arginine methyltransferases (PRMT1-9) have emerged, through their ability to methylate histones and non-histone substrates, as essential regulators of cancers. Here, we present an updated overview of the mechanisms by which PRMT1 and PRMT5, two major members of the PRMT family, control important signaling pathways impacting breast tumorigenesis, highlighting them as putative therapeutic targets.

Plant ARGONAUTE (AGO) proteins play pivotal roles regulating gene expression through small RNA (sRNA) -guided mechanisms. Among the 10 AGO proteins in Arabidopsis thaliana, AGO1 stands out as the main effector of post-transcriptional gene silencing. Intriguingly, a specific region of AGO1, its N-terminal extension (NTE), has garnered attention in recent studies due to its involvement in diverse regulatory functions, including subcellular localization, sRNA loading and interactions with regulatory factors. In the field of post-translational modifications (PTMs), little is known about arginine methylation in Arabidopsis AGOs. In this study, we show that NTE of AGO1 (NTEAGO1) undergoes symmetric arginine dimethylation at specific residues. Moreover, NTEAGO1 interacts with the methyltransferase PRMT5, which catalyzes its methylation. Notably, we observed that the lack of symmetric dimethylarginine has no discernible impact on AGO1's subcellular localization or miRNA loading capabilities. However, the absence of PRMT5 significantly alters the loading of a subgroup of sRNAs into AGO1 and reshapes the NTEAGO1 interactome. Importantly, our research shows that symmetric arginine dimethylation of NTEs is a common process among Arabidopsis AGOs, with AGO1, AGO2, AGO3 and AGO5 undergoing this PTM. Overall, this work deepens our understanding of PTMs in the intricate landscape of RNA-associated gene regulation., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Proper protein arginine methylation by protein arginine methyltransferase 1 (PRMT1) is critical for maintaining cellular health, while dysregulation is often associated with disease. How the activity of PRMT1 is regulated is therefore paramount, but is not clearly understood. Several studies have observed higher order oligomeric species of PRMT1, but it is unclear if these exist at physiological concentrations and there is confusion in the literature about how oligomerization affects activity. We therefore sought to determine which oligomeric species of PRMT1 are physiologically relevant, and quantitatively correlate activity with specific oligomer forms. Through quantitative western blotting, we determined that concentrations of PRMT1 available in a variety of human cell lines are in the sub-micromolar to low micromolar range. Isothermal spectral shift binding data were modeled to a monomer/dimer/tetramer equilibrium with an EC 50 for tetramer dissociation of ~20 nM. A combination of sedimentation velocity and Native polyacrylamide gel electrophoresis experiments directly confirmed that the major oligomeric species of PRMT1 at physiological concentrations would be dimers and tetramers. Surprisingly, the methyltransferase activity of a dimeric PRMT1 variant is similar to wild type, tetrameric PRMT1 with some purified substrates, but dimer and tetramer forms of PRMT1 show differences in catalytic efficiencies and substrate specificity for other substrates. Our results define an oligomerization paradigm for PRMT1, show that the biophysical characteristics of PRMT1 are poised to support a monomer/dimer/tetramer equilibrium in vivo, and suggest that the oligomeric state of PRMT1 could be used to regulate substrate specificity., (© 2024 The Author(s). Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)

Gastric cancer (GC) is a common form of cancer and the leading cause of cancer-related deaths worldwide. Chemotherapy is the primary treatment for patients with unresectable or partially resectable GC. However, its adverse effects and chemoresistance greatly restrict its applicability and efficacy. Although HER2-targeted therapy and immunotherapy have been successfully used for GC treatment, their beneficial population is limited. To expand the range of cancer treatments, drug repurposing has emerged as a promising strategy. In this study, we evaluated the potential of Metformin, an oral anti-hyperglycemic agent, to suppress GC progression both in vivo and in vitro. Functional investigations showed that Metformin significantly inhibits GC proliferation and migration. Furthermore, we discovered that Metformin bound and disrupted STAT1 phosphorylation, inhibiting PRMT1 expression and consequently GC progression. In conclusion, our study not only provides further evidence for the anti-GC role of Metformin but also identifies the direct target mediating the tumor-inhibitory effects of Metformin in GC., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The tumour suppressor p16/CDKN2A and the metabolic gene, methyl-thio-adenosine phosphorylase (MTAP), are frequently co-deleted in some of the most aggressive and currently untreatable cancers. Cells with MTAP deletion are vulnerable to inhibition of the metabolic enzyme, methionine-adenosyl transferase 2A (MAT2A), and the protein arginine methyl transferase (PRMT5). This synthetic lethality has paved the way for the rapid development of drugs targeting the MAT2A/PRMT5 axis. MAT2A and its liver- and pancreas-specific isoform, MAT1A, generate the universal methyl donor S-adenosylmethionine (SAM) from ATP and methionine. Given the pleiotropic role SAM plays in methylation of diverse substrates, characterising the extent of SAM depletion and downstream perturbations following MAT2A/MAT1A inhibition (MATi) is critical for safety assessment. We have assessed in vivo target engagement and the resultant systemic phenotype using multi-omic tools to characterise response to a MAT2A inhibitor (AZ'9567). We observed significant SAM depletion and extensive methionine accumulation in the plasma, liver, brain and heart of treated rats, providing the first assessment of both global SAM depletion and evidence of hepatic MAT1A target engagement. An integrative analysis of multi-omic data from liver tissue identified broad perturbations in pathways covering one-carbon metabolism, trans-sulfuration and lipid metabolism. We infer that these pathway-wide perturbations represent adaptive responses to SAM depletion and confer a risk of oxidative stress, hepatic steatosis and an associated disturbance in plasma and cellular lipid homeostasis. The alterations also explain the dramatic increase in plasma and tissue methionine, which could be used as a safety and PD biomarker going forward to the clinic., (© 2024. The Author(s).)

Background and Aims: Hepatic lipogenesis is elevated in nutrient abundant conditions to convert the excess carbohydrate into triacylglycerol (TAG). Fatty acyl moiety of TAG is eventually transported into adipose tissues by very low density lipoprotein, leading to the accumulation of TAG as a preferred storage form of excess energy. Disruption of the balance between TAG clearance and synthesis leads to the accumulation of lipids in the liver, leading to the progression of non-alcoholic fatty liver disease (NAFLD) including non-alcoholic steatohepatitis. Protein arginine methyltransferase (PRMT) 6 has been linked to the various metabolic processes including hepatic gluconeogenesis, muscle atrophy and lipodystrophy in mouse models. However, the role of PRMT6 in the control of hepatic lipogenesis has not been elucidated to date., Methods: We assessed the interaction between PRMT6 and LXR alpha by using co-immunoprecipitation assay. The specific arginine residue of LXR alpha that is methylated by PRMT6 was assessed by LC-MS/MS assay and the functional consequences of LXR alpha methylation was explored by mSREBP-1c luciferase assay. The effect of PRMT6 on hepatic lipogenesis was assessed by adenovirus-mediated ectopic expression of PRMT6 or knockdown of PRMT6 via shRNA in hepatocytes. Finally, the role of PRMT6 in hepatic lipid metabolism in vivo was explored by either ectopic expression of LXR alpha mutant that is defective in PRMT6-mediated arginine methylation or knockdown of PRMT6 in liver., Results: We found that promoter activity of sterol regulatory element binding protein (SREBP) 1c is robustly activated by PRMT6. Interestingly, we demonstrated that PRMT6 binds to LXR alpha, a transcription factor for SREBP-1c, via its LXXLL motif, leading to the asymmetric dimethylation of an arginine residue and activation of this protein. Indeed, ectopic expression of PRMT6 in hepatocytes led to the enhanced expression of LXR alpha target genes in the lipogenic pathway. Conversely, genetic or pharmacological inhibition of PRMT6 diminished expression of lipogenic genes and the lipid accumulation in primary hepatocytes. Mechanistically, we found that asymmetric dimethylation of LXR alpha led to the dissociation of small heterodimer partner (SHP), a transcriptional co-inhibitor of this factor, resulting in the activation of LXR alpha-mediated transcriptional process. Finally, we showed that disruption of asymmetric dimethylation of LXR alpha in the liver led to the diminished expression of genes in the lipogenesis, resulting in the reduced hepatic lipid accumulation in high fat diet-fed mice in vivo., Conclusions: We showed that PRMT6 modulates LXR alpha activity by conferring asymmetric dimethylation of arginine 253, thus blocking SHP-mediated inhibition and promoting hepatic lipid accumulation. These results suggest that PRMT6 is critical in the control of lipid homeostasis by regulation of LXR alpha-mediated lipogenesis in the liver., Competing Interests: Declaration of competing interest The authors have declared no conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

PRMT5 is a widely expressed arginine methyltransferase that regulates processes involved in tumor cell proliferation and survival. In the study described here, we investigated whether PRMT5 provides a target for tumor radiosensitization. Knockdown of PRMT5 using siRNA enhanced the radiosensitivity of a panel of cell lines corresponding to tumor types typically treated with radiotherapy. To extend these studies to an experimental therapeutic setting, the PRMT5 inhibitor LLY-283 was used. Exposure of the tumor cell lines to LLY-283 decreased PRMT5 activity and enhanced their radiosensitivity. This increase in radiosensitivity was accompanied by an inhibition of DNA double-strand break repair as determined by γH2AX foci and neutral comet analyses. For a normal fibroblast cell line, although LLY-283 reduced PRMT5 activity, it had no effect on their radiosensitivity. Transcriptome analysis of U251 cells showed that LLY-283 treatment reduced the expression of genes and altered the mRNA splicing pattern of genes involved in the DNA damage response. Subcutaneous xenografts were then used to evaluate the in vivo response to LLY-283 and radiation. Treatment of mice with LLY-283 decreased tumor PRMT5 activity and significantly enhanced the radiation-induced growth delay. These results suggest that PRMT5 is a tumor selective target for radiosensitization., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Invasion and migration are the key hallmarks of cancer, and aggressive growth is a major factor contributing to treatment failure and poor prognosis in glioblastoma. Protein arginine methyltransferase 6 (PRMT6), as an epigenetic regulator, has been confirmed to promote the malignant proliferation of glioblastoma cells in previous studies. However, the effects of PRMT6 on glioblastoma cell invasion and migration and its underlying mechanisms remain elusive. Here, we report that PRMT6 functions as a driver element for tumor cell invasion and migration in glioblastoma. Bioinformatics analysis and glioma sample detection results demonstrated that PRMT6 is highly expressed in mesenchymal subtype or invasive gliomas, and is significantly negatively correlated with their prognosis. Inhibition of PRMT6 (using PRMT6 shRNA or inhibitor EPZ020411) reduces glioblastoma cell invasion and migration in vitro, whereas overexpression of PRMT6 produces opposite effects. Then, we identified that PRMT6 maintains the protein stability of EZH2 by inhibiting the degradation of EZH2 protein, thereby mediating the invasion and migration of glioblastoma cells. Further mechanistic investigations found that PRMT6 inhibits the transcription of TRAF6 by activating the histone methylation mark (H3R2me2a), and reducing the interaction between TRAF6 and EZH2 to enhance the protein stability of EZH2 in glioblastoma cells. Xenograft tumor assay and HE staining results showed that the expression of PRMT6 could promote the invasion of glioblastoma cells in vivo, the immunohistochemical staining results of mouse brain tissue tumor sections also confirmed the regulatory relationship between PRMT6, TRAF6, and EZH2. Our findings illustrate that PRMT6 suppresses TRAF6 transcription via H3R2me2a to enhance the protein stability of EZH2 to facilitate glioblastoma cell invasion and migration. Blocking the PRMT6-TRAF6-EZH2 axis is a promising strategy for inhibiting glioblastoma cell invasion and migration., (© 2024. The Author(s).)

Glycine- and arginine-rich (GAR) motifs, commonly found in RNA-binding and -processing proteins, can be symmetrically (SDMA) or asymmetrically (ADMA) dimethylated at the arginine residue by protein arginine methyltransferases. Arginine-methylated protein motifs are usually read by Tudor domain-containing proteins. Here, using a GFP-Trap, we identify a non-Tudor domain protein, squamous cell carcinoma antigen recognized by T cells 3 (SART3), as a reader for SDMA-marked GAR motifs. Structural analysis and mutagenesis of SART3 show that aromatic residues lining a groove between two adjacent aromatic-rich half-a-tetratricopeptide (HAT) repeat domains are essential for SART3 to recognize and bind to SDMA-marked GAR motif peptides, as well as for the interaction between SART3 and the GAR-motif-containing proteins fibrillarin and coilin. Further, we show that the loss of this reader ability affects RNA splicing. Overall, our findings broaden the range of potential SDMA readers to include HAT domains., Competing Interests: Declaration of interests M.T.B. is the co-founder of EpiCypher., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Non-alcoholic fatty liver disease (NAFLD) has emerged as the leading cause of chronic liver disease worldwide. Caspase 8 and FADD-like apoptosis regulator (CFLAR) has been identified as a potent factor in mitigating non-alcoholic steatohepatitis (NASH) by inhibiting the N-terminal dimerization of apoptosis signal-regulating kinase 1 (ASK1). While arginine methyltransferase 1 (PRMT1) was previously reported to be associated with increased hepatic glucose production, its involvement in hepatic lipid metabolism remains largely unexplored. The interaction between PRMT1 and CFLAR and the methylation of CFLAR were verified by Co-IP and immunoblotting assays. Recombinant adenoviruses were generated for overexpression or knockdown of PRMT1 in hepatocytes. The role of PRMT1 in NAFLD was investigated in normal and high-fat diet-induced obese mice. In this study, we found a significant upregulation of PRMT1 and downregulation of CFLAR after 48h of fasting, while the latter significantly rebounded after 12h of refeeding. The expression of PRMT1 increased in the livers of mice fed a methionine choline-deficient (MCD) diet and in hepatocytes challenged with oleic acid (OA)/palmitic acid (PA). Overexpression of PRMT1 not only inhibited the expression of genes involved in fatty acid oxidation (FAO) and promoted the expression of genes involved in fatty acid synthesis (FAS), resulting in increased triglyceride accumulation in primary hepatocytes, but also enhanced the gluconeogenesis of primary hepatocytes. Conversely, knockdown of hepatic PRMT1 significantly alleviated MCD diet-induced hepatic lipid metabolism abnormalities and liver injury in vivo, possibly through the upregulation of CFLAR protein levels. Knockdown of PRMT1 suppressed the expression of genes related to FAS and enhanced the expression of genes involved in FAO, causing decreased triglyceride accumulation in OA/PA-treated primary hepatocytes in vitro. Although short-term overexpression of PRMT1 had no significant effect on hepatic triglyceride levels under physiological conditions, it resulted in increased serum triglyceride and fasting blood glucose levels in normal C57BL/6J mice. More importantly, PRMT1 was observed to interact with and methylate CFLAR, ultimately leading to its ubiquitination-mediated protein degradation. This process subsequently triggered the activation of c-Jun N-terminal kinase 1 (JNK1) and lipid deposition in primary hepatocytes. Together, these results suggested that PRMT1-mediated methylation of CFLAR plays a critical role in hepatic lipid metabolism. Targeting PRMT1 for drug design may represent a promising strategy for the treatment of NAFLD.

Abnormal epigenetic modifications are involved in the regulation of Warburg effect in tumor cells. Protein arginine methyltransferases (PRMTs) mediate arginine methylation and have critical functions in cellular responses. PRMTs are deregulated in a variety of cancers, but their precise roles in Warburg effect in cancer is largely unknown. Experiments from the current study showed that PRMT1 was highly expressed under conditions of glucose sufficiency. PRMT1 induced an increase in the PKM2/PKM1 ratio through upregulation of PTBP1, in turn, promoting aerobic glycolysis in non-small cell lung cancer (NSCLC). The PRMT1 level in p53-deficient and p53-mutated NSCLC remained relatively unchanged while the expression was reduced in p53 wild-type NSCLC under conditions of glucose insufficiency. Notably, p53 activation under glucose-deficient conditions could suppress USP7 and further accelerate the polyubiquitin-dependent degradation of PRMT1. Melatonin, a hormone that inhibits glucose intake, markedly suppressed cell proliferation of p53 wild-type NSCLC, while a combination of melatonin and the USP7 inhibitor P5091 enhanced the anticancer activity in p53-deficient NSCLC. Our collective findings support a role of PRMT1 in the regulation of Warburg effect in NSCLC. Moreover, combination treatment with melatonin and the USP7 inhibitor showed good efficacy, providing a rationale for the development of PRMT1-based therapy to improve p53-deficient NSCLC outcomes., (© 2024. The Author(s).)

Protein arginine methyltransferase CARM1 has been shown to methylate a large number of non-histone proteins, and play important roles in gene transcriptional activation, cell cycle progress, and tumorigenesis. However, the critical substrates through which CARM1 exerts its functions remain to be fully characterized. Here, we reported that CARM1 directly interacts with the GATAD2A/2B subunit in the nucleosome remodeling and deacetylase (NuRD) complex, expanding the activities of NuRD to include protein arginine methylation. CARM1 and NuRD bind and activate a large cohort of genes with implications in cell cycle control to facilitate the G1 to S phase transition. This gene activation process requires CARM1 to hypermethylate GATAD2A/2B at a cluster of arginines, which is critical for the recruitment of the NuRD complex. The clinical significance of this gene activation mechanism is underscored by the high expression of CARM1 and NuRD in breast cancers, and the fact that knockdown CARM1 and NuRD inhibits cancer cell growth in vitro and tumorigenesis in vivo. Targeting CARM1-mediated GATAD2A/2B methylation with CARM1 specific inhibitors potently inhibit breast cancer cell growth in vitro and tumorigenesis in vivo. These findings reveal a gene activation program that requires arginine methylation established by CARM1 on a key chromatin remodeler, and targeting such methylation might represent a promising therapeutic avenue in the clinic., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Emerging evidence indicates that arginine methylation promotes the stability of arginine-glycine-rich (RGG) motif-containing RNA-binding proteins (RBPs) and regulates gene expression. Here, we report that post-translational modification of FXR1 enhances the binding with mRNAs and is involved in cancer cell growth and proliferation. Independent point mutations in arginine residues of FXR1's nuclear export signal (R386 and R388) and RGG (R453, R455 and R459) domains prevent it from binding to RNAs that form G-quadruplex (G4) RNA structures. Disruption of G4-RNA structures by lithium chloride failed to bind with FXR1, indicating its preference for G4-RNA structure containing mRNAs. Furthermore, loss-of-function of PRMT5 inhibited FXR1 methylation both in vivo and in vitro, affecting FXR1 protein stability, inhibiting RNA-binding activity and cancer cell growth and proliferation. Finally, the enhanced crosslinking and immunoprecipitation (eCLIP) analyses reveal that FXR1 binds with the G4-enriched mRNA targets such as AHNAK, MAP1B, AHNAK2, HUWE1, DYNC1H1 and UBR4 and controls its mRNA expression in cancer cells. Our findings suggest that PRMT5-mediated FXR1 methylation is required for RNA/G4-RNA binding, which promotes gene expression in cancer cells. Thus, FXR1's structural characteristics and affinity for RNAs preferentially G4 regions provide new insights into the molecular mechanism of FXR1 in oral cancer cells., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Chronic varicella zoster virus (VZV) infection induced neuroinflammatory condition is the critical pathology of post-herpetic neuralgia (PHN). The immune escape mechanism of VZV remains elusive. As to mice have no VZV infection receptor, herpes simplex virus type 1 (HSV-1) infection is a well established PHN mice model. Transcriptional expression analysis identified that the protein arginine methyltransferases 6 (Prmt6) was upregulated upon HSV-1 infection, which was further confirmed by immunofluorescence staining in spinal dorsal horn. Prmt6 deficiency decreased HSV-1-induced neuroinflammation and PHN by enhancing antiviral innate immunity and decreasing HSV-1 load in vivo and in vitro. Overexpression of Prmt6 in microglia dampened antiviral innate immunity and increased HSV-1 load. Mechanistically, Prmt6 methylated and inactivated STING, resulting in reduced phosphorylation of TANK binding kinase-1 (TBK1) and interferon regulatory factor 3 (IRF3), diminished production of type I interferon (IFN-I) and antiviral innate immunity. Furthermore, intrathecal or intraperitoneal administration of the Prmt6 inhibitor EPZ020411 decreased HSV-1-induced neuroinflammation and PHN by enhancing antiviral innate immunity and decreasing HSV-1 load. Our findings revealed that HSV-1 escapes antiviral innate immunity and results in PHN by upregulating Prmt6 expression and inhibiting the cGAS-STING pathway, providing novel insights and a potential therapeutic target for PHN., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Purpose: Due to intrinsic defensive response, ferroptosis-activating targeted therapy fails to achieve satisfactory clinical benefits. Though p62-Keap1-Nrf2 axis is activated to form a negative feedback loop during ferroptosis induction, how p62 is activated remains largely unknown. Methods: MTS assay was applied to measure cell growth. Lipid ROS was detected with C11-BODIPY reagent by flow cytometer. Quantitative real-time PCR (qPCR) and western blotting were performed to determine mRNA and protein level. Immunofluorescence (IF) was performed to examine the distribution of proteins. Fluorescence recovery after photobleaching (FRAP) was adopted to evaluate p62 phase separation. Immunoprecipitation (IP), co-IP and Proximal ligation assay (PLA) were performed to detected protein posttranslational modifications and protein-protein interactions. Tumor xenograft model was employed to inspect in vivo growth of pancreatic cancer cells. Results: Upon ferroptosis induction, Nuclear Factor E2 Related Factor 2 (Nrf2) protein and its downstream genes such as HMOX1 and NQO1 were upregulated. Knockdown of p62 significantly reversed Nrf2 upregulation and Keap1 decrease after ferroptosis induction. Knockdown of either p62 or Nrf2 remarkably sensitized ferroptosis induction. Due to augmented p62 phase separation, formation of p62 bodies were increased to recruit Keap1 after ferroptosis induction. Protein arginine methyltransferase 6 (PRMT6) mediated asymmetric dimethylarginine (ADMA) of p62 to increase its oligomerization, promoting p62 phase separation and p62 body formation. Knockdown of p62 or PRMT6 notably sensitized pancreatic cancer cells to ferroptosis both in vitro and in vivo through suppressing Nrf2 signaling. Conclusion: During ferroptosis induction, PRMT6 mediated p62 ADMA to promote its phase separation, sequestering Keap1 to activate Nrf2 signaling and inhibit ferroptosis. Therefore, targeting PRMT6-mediated p62 ADMA could be a new option to sensitize ferroptosis for cancer treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Cardiovascular diseases (CVDs) and metabolic disorders stand as formidable challenges that significantly impact the clinical outcomes and living quality for afflicted individuals. An intricate comprehension of the underlying mechanisms is paramount for the development of efficacious therapeutic strategies. Protein arginine methyltransferases (PRMTs), a class of enzymes responsible for the precise regulation of protein methylation, have ascended to pivotal roles and emerged as crucial regulators within the intrinsic pathophysiology of these diseases. Herein, we review recent advancements in research elucidating on the multifaceted involvements of PRMTs in cardiovascular system and metabolic diseases, contributing significantly to deepen our understanding of the pathogenesis and progression of these maladies. In addition, this review provides a comprehensive analysis to unveil the distinctive roles of PRMTs across diverse cell types implicated in cardiovascular and metabolic disorders, which holds great potential to reveal novel therapeutic interventions targeting PRMTs, thus presenting promising perspectives to effectively address the substantial global burden imposed by CVDs and metabolic disorders.

Background: Excessive fatty acids in the liver lead to the accumulation of lipotoxic lipids and then cellular stress to further evoke the related disease, like non-alcoholic fatty liver disease (NAFLD). As reported, fatty acid stimulation can cause some specific miRNA dysregulation, which caused us to investigate the relationship between miRNA biogenesis and fatty acid overload., Methods: Gene expression omnibus (GEO) dataset analysis, miRNA-seq, miRNA cleavage assay, RT-qPCR, western blotting, immunofluorescence and co-immunoprecipitation (co-IP) were used to reveal the change of miRNAs under pathological status and explore the relevant mechanism. High fat, high fructose, high cholesterol (HFHFrHC) diet-fed mice transfected with AAV2/8-shDrosha or AAV2/8-shPRMT5 were established to investigate the in vivo effects of Drosha or PRMT5 on NAFLD phenotype., Results: We discovered that the cleavage of miRNAs was inhibited by analysing miRNA contents and detecting some representative pri-miRNAs in multiple mouse and cell models, which was further verified by the reduction of the Microprocessor activity in the presence of palmitic acid (PA). In vitro, PA could induce Drosha, the core RNase III in the Microprocessor complex, degrading through the proteasome-mediated pathway, while in vivo, knockdown of Drosha significantly promoted NAFLD to develop to a more serious stage. Mechanistically, our results demonstrated that PA can increase the methyltransferase activity of PRMT5 to degrade Drosha through MDM2, a ubiquitin E3 ligase for Drosha. The above results indicated that PRMT5 may be a critical regulator in lipid metabolism during NAFLD, which was confirmed by the knocking down of PRMT5 improved aberrant lipid metabolism in vitro and in vivo., Conclusions: We first demonstrated the relationship between miRNA dosage and NAFLD and proved that PA can activate the PRMT5-MDM2-Drosha signalling pathway to regulate miRNA biogenesis., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The Dickkopf family proteins (DKKs) are strong Wnt signaling antagonists that play a significant role in colorectal cancer (CRC) development and progression. Recent work has shown that DKKs, mainly DKK1, are associated with the induction of chemoresistance in CRC and that DKK1 expression in cancer cells correlates with that of protein arginine N-methyltransferase 5 (PRMT5). This points to the presence of a regulatory loop between DKK1 and PRMT5. Herein, we addressed the question of whether PRMT5 contributes to DKK1 expression in CRC and hence CRC chemoresistance. Both in silico and in vitro approaches were used to explore the relationship between PRMT5 and different DKK members. Our data demonstrated that DKK1 expression is significantly upregulated in CRC clinical samples, KRAS-mutated CRC in particular and that the levels of DKK1 positively correlate with PRMT5 activation. Chromatin immunoprecipitation (ChIP) data indicated a possible epigenetic role of PRMT5 in regulating DKK1, possibly through the symmetric dimethylation of H3R8. Knockdown of DKK1 or treatment with the PRMT5 inhibitor CMP5 in combination with doxorubicin yielded a synergistic anti-tumor effect in KRAS mutant, but not KRAS wild-type, CRC cells. These findings suggest that PRMT5 regulates DKK1 expression in CRC and that inhibition of PRMT5 modulates DKK1 expression in such a way that reduces CRC cell growth., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

The dynamic regulation of mitochondria through fission and fusion is essential for maintaining cellular homeostasis. In this study, we discovered a role of coactivator-associated arginine methyltransferase 1 (CARM1) in mitochondrial dynamics. CARM1 methylates specific residues (R403 and R634) on dynamin-related protein 1 (DRP1). Methylated DRP1 interacts with mitochondrial fission factor (Mff) and forms self-assembly on the outer mitochondrial membrane, thereby triggering fission, reducing oxygen consumption, and increasing reactive oxygen species (ROS) production. This sets in motion a feedback loop that facilitates the translocation of CARM1 from the nucleus to the cytoplasm, enhancing DRP1 methylation and ROS production through mitochondrial fragmentation. Consequently, ROS reinforces the CARM1-DRP1-ROS axis, resulting in cellular senescence. Depletion of CARM1 or DRP1 impedes cellular senescence by reducing ROS accumulation. The uncovering of the above-described mechanism fills a missing piece in the vicious cycle of ROS-induced senescence and contributes to a better understanding of the aging process., Competing Interests: Declaration of Competing interest The authors declared that there are no conflicts of interest., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Arginine methylation, which is catalyzed by protein arginine methyltransferases (Prmts), is known to play a key role in various biological processes. However, the function of Prmts in osteogenic differentiation of mesenchymal stem cells (MSCs) has not been clearly understood. In the current study, we attempted to elucidate a positive role of Prmt7 in osteogenic differentiation. Prmt7-depleted C3H/10T1/2 cells or bone marrow mesenchymal stem cells (BMSCs) showed the attenuated expression of osteogenic specific genes and Alizarin red staining compared to the wild-type cells. Furthermore, we found that Prmt7 deficiency reduced the activation of bone morphogenetic protein (BMP) signaling cascade, which is essential for the regulation of cell fate commitment and osteogenesis. Taken together, our data indicate that Prmt7 plays important regulatory roles in osteogenic differentiation. [BMB Reports 2024; 57(7): 330-335].

PRMT6 is a member of the protein arginine methyltransferase family, which participates in a variety of physical processes and plays an important role in the occurrence and development of tumors. Using small molecules to design and synthesize targeted protein degraders is a new strategy for drug development. Here, we report the first-in-class degrader SKLB-0124 for PRMT6 based on the hydrophobic tagging (HyT) method.Importantly, SKLB-0124 induced proteasome dependent degradation of PRMT6 and significantly inhibited the proliferation of HCC827 and MDA-MB-435 cells. Moreover, SKLB-0124 effectively induced apoptosis and cell cycle arrest in these two cell lines. Our data clarified that SKLB-0124 is a promising selective PRMT6 degrader for cancer therapy which is worthy of further evaluation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Coactivator-associated arginine methyltransferase 1 (CARM1) is a protein arginine methyltransferase that deposits asymmetrical dimethylation marks on both histone and nonhistone substrates. The regulatory role of CARM1 in transcription was first identified in estrogen receptor positive (ER+) breast cancer. Since then, the mechanism of CARM1 in activating ER-target genes has been further interrogated. CARM1 is expressed at the highest level in ER negative (ER-) breast cancer and higher expression correlates with poor prognosis, suggesting an oncogenic role of CARM1. Indeed, in ER- breast cancer, CARM1 can promote proliferation and metastasis at least partly through methylation of proteins and activation of oncogenes. In this review, we summarize the mechanisms of transcriptional activation by CARM1 in breast cancer. The methyltransferase activity of CARM1 is important for many of its functions; here, we also highlight the nonenzymatic roles of CARM1. We also cover the biological processes regulated by CARM1 that are often deregulated in cancer and the ways to harness CARM1 in cancer treatment., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com. See the journal About page for additional terms.)

Stress granules (SGs) are membrane-less organelles (MLOs) or cytosolic compartments formed upon exposure to environmental cell stress-inducing stimuli. SGs are based on ribonucleoprotein complexes from a set of cytoplasmic proteins and mRNAs, blocked in translation due to stress cell-induced polysome disassembly. Post-translational modifications (PTMs) such as methylation, are involved in SG assembly, with the methylation writer PRMT1 and its reader TDRD3 colocalizing to SGs. However, the role of this writer-reader system in SG assembly remains unclear. Here, we found that PRMT1 methylates SG constituent RNA-binding proteins (RBPs) on their RGG motifs. Besides, we report that TDRD3, as a reader of asymmetric dimethylarginines, enhances RNA binding to recruit additional RNAs and RBPs, lowering the percolation threshold and promoting SG assembly. Our study enriches our understanding of the molecular mechanism of SG formation by elucidating the functions of PRMT1 and TDRD3. We anticipate that our study will provide a new perspective for comprehensively understanding the functions of PTMs in liquid-liquid phase separation driven condensate assembly., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Arginine methylation is catalyzed by protein arginine methyltransferases (PRMTs) and is involved in various cellular processes, including cancer development. PRMT2 expression is increased in several cancer types although its role in acute myeloid leukemia (AML) remains unknown. Here, we investigate the role of PRMT2 in a cohort of patients with AML, PRMT2 knockout AML cell lines as well as a Prmt2 knockout mouse model. In patients, low PRMT2 expressors are enriched for inflammatory signatures, including the NF-κB pathway, and show inferior survival. In keeping with a role for PRMT2 in control of inflammatory signaling, bone marrow-derived macrophages from Prmt2 KO mice display increased pro-inflammatory cytokine signaling upon LPS treatment. In PRMT2-depleted AML cell lines, aberrant inflammatory signaling has been linked to overproduction of IL6, resulting from a deregulation of the NF-κB signaling pathway, therefore leading to hyperactivation of STAT3. Together, these findings identify PRMT2 as a key regulator of inflammation in AML., (© 2024. The Author(s).)

DNA replication stress (RS) is a widespread phenomenon in carcinogenesis, causing genomic instability and extensive chromatin alterations. DNA damage leads to activation of innate immune signaling, but little is known about transcriptional regulators mediating such signaling upon RS. Using a chemical screen, we identified protein arginine methyltransferase 5 (PRMT5) as a key mediator of RS-dependent induction of interferon-stimulated genes (ISGs). This response is also associated with reactivation of endogenous retroviruses (ERVs). Using quantitative mass spectrometry, we identify proteins with PRMT5-dependent symmetric dimethylarginine (SDMA) modification induced upon RS. Among these, we show that PRMT5 targets and modulates the activity of ZNF326, a zinc finger protein essential for ISG response. Our data demonstrate a role for PRMT5-mediated SDMA in the context of RS-induced transcriptional induction, affecting physiological homeostasis and cancer therapy.

Cancer cells are often addicted to serine synthesis to support growth. How serine synthesis is regulated in cancer is not well understood. We recently demonstrated protein arginine methyltransferase 1 (PRMT1) is upregulated in hepatocellular carcinoma (HCC) to methylate and activate phosphoglycerate dehydrogenase (PHGDH), thereby promoting serine synthesis. However, the mechanisms underlying PRMT1 upregulation and regulation of PRMT1-PHGDH axis remain unclear. Here, we show the E3 ubiquitin ligase F-box-only protein 7 (FBXO7) inhibits serine synthesis in HCC by binding PRMT1, inducing lysine 37 ubiquitination, and promoting proteosomal degradation of PRMT1. FBXO7-mediated PRMT1 downregulation cripples PHGDH arginine methylation and activation, resulting in impaired serine synthesis, accumulation of reactive oxygen species (ROS), and inhibition of HCC cell growth. Notably, FBXO7 is significantly downregulated in human HCC tissues, and inversely associated with PRMT1 protein and PHGDH methylation level. Overall, our study provides mechanistic insights into the regulation of cancer serine synthesis by FBXO7-PRMT1-PHGDH axis, and will facilitate the development of serine-targeting strategies for cancer therapy., (© 2024. The Author(s).)

β-Thalassemia is an inherited genetic disorder associated with β-globin chain synthesis, which ultimately becomes anemia. Adenosine-2,3-dialdehyde, by inhibiting arginine methyl transferase 5 (PRMT5), can induce fetal hemoglobin (HbF) levels. Hence, the materialization of PRMT5 inhibitors is considered a promising therapy in the management of β-thalassemia. This study conducted a virtual screening of certain compounds similar to 5'-deoxy-5'methyladenosine (3XV) using the PubChem database. The top 10 compounds were chosen based on the best docking scores, while their interactions with the PRMT5 active site were analyzed. Further, the top two compounds demonstrating the lowest binding energy were subjected to drug-likeness analysis and pharmacokinetic property predictions, followed by molecular dynamics simulation studies. Based on the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) score and molecular interactions, (3R,4S)-2-(6-aminopurin-9-yl)-5-[(4-ethylcyclohexyl)sulfanylmethyl]oxolane-3,4-diol (TOP1) and 2-(6-Aminopurin-9-yl)-5-[(6-aminopurin-9-yl)methylsulfanylmethyl]oxolane-3,4-diol (TOP2) were identified as potential hit compounds, while TOP1 exhibited higher binding affinity and stabler binding capabilities than TOP2 during molecular dynamics simulation (MDS) analysis. Taken together, the outcomes of our study could aid researchers in identifying promising PRMT5 inhibitors. Moreover, further investigations through in vivo and in vitro experiments would unquestionably confirm that this compound could be employed as a therapeutic drug in the management of β-thalassemia.

Although both protein arginine methylation (PRMT) and jasmonate (JA) signaling are crucial for regulating plant development, the relationship between these processes in the control of spikelet development remains unclear. In this study, we used the CRISPR/Cas9 technology to generate two OsPRMT6a loss-of-function mutants that exhibit various abnormal spikelet structures. Interestingly, we found that OsPRMT6a can methylate arginine residues in JA signal repressors OsJAZ1 and OsJAZ7. We showed that arginine methylation of OsJAZ1 enhances the binding affinity of OsJAZ1 with the JA receptors OsCOI1a and OsCOI1b in the presence of JAs, thereby promoting the ubiquitination of OsJAZ1 by the SCF OsCOI1a/OsCOI1b complex and degradation via the 26S proteasome. This process ultimately releases OsMYC2, a core transcriptional regulator in the JA signaling pathway, to activate or repress JA-responsive genes, thereby maintaining normal plant (spikelet) development. However, in the osprmt6a-1 mutant, reduced arginine methylation of OsJAZ1 impaires the interaction between OsJAZ1 and OsCOI1a/OsCOI1b in the presence of JAs. As a result, OsJAZ1 proteins become more stable, repressing JA responses, thus causing the formation of abnormal spikelet structures. Moreover, we discovered that JA signaling reduces the OsPRMT6a mRNA level in an OsMYC2-dependent manner, thereby establishing a negative feedback loop to balance JA signaling. We further found that OsPRMT6a-mediated arginine methylation of OsJAZ1 likely serves as a switch to tune JA signaling to maintain normal spikelet development under harsh environmental conditions such as high temperatures. Collectively, our study establishes a direct molecular link between arginine methylation and JA signaling in rice., (Copyright © 2024 The Author. Published by Elsevier Inc. All rights reserved.)

CARM1 (coactivator associated arginine methyltransferase 1) has recently emerged as a powerful regulator of skeletal muscle biology. However, the molecular mechanisms by which the methyltransferase remodels muscle remain to be fully understood. In this study, carm1 skeletal muscle-specific knockout (mKO) mice exhibited lower muscle mass with dysregulated macroautophagic/autophagic and atrophic signaling, including depressed AMP-activated protein kinase (AMPK) site-specific phosphorylation of ULK1 (unc-51 like autophagy activating kinase 1; Ser555) and FOXO3 (forkhead box O3; Ser588), as well as MTOR (mechanistic target of rapamycin kinase)-induced inhibition of ULK1 (Ser757), along with AKT/protein kinase B site-specific suppression of FOXO1 (Ser256) and FOXO3 (Ser253). In addition to lower mitophagy and autophagy flux in skeletal muscle, carm1 mKO led to increased mitochondrial PRKN/parkin accumulation, which suggests that CARM1 is required for basal mitochondrial turnover and autophagic clearance. carm1 deletion also elicited PPARGC1A (PPARG coactivator 1 alpha) activity and a slower, more oxidative muscle phenotype. As such, these carm1 mKO-evoked adaptations disrupted mitophagy and autophagy induction during food deprivation and collectively served to mitigate fasting-induced muscle atrophy. Furthermore, at the threshold of muscle atrophy during food deprivation experiments in humans, skeletal muscle CARM1 activity decreased similarly to our observations in mice, and was accompanied by site-specific activation of ULK1 (Ser757), highlighting the translational impact of the methyltransferase in human skeletal muscle. Taken together, our results indicate that CARM1 governs mitophagic, autophagic, and atrophic processes fundamental to the maintenance and remodeling of muscle mass. Targeting the enzyme may provide new therapeutic approaches for mitigating skeletal muscle atrophy. Abbreviation : ADMA: asymmetric dimethylarginine; AKT/protein kinase B: AKT serine/threonine kinase; AMPK: AMP-activated protein kinase; ATG: autophagy related; BECN1: beclin 1; BNIP3: BCL2 interacting protein 3; CARM1: coactivator associated arginine methyltransferase 1; Col: colchicine; CSA: cross-sectional area; CTNS: cystinosin, lysosomal cystine transporter; EDL: extensor digitorum longus; FBXO32/MAFbx: F-box protein 32; FOXO: forkhead box O; GAST: gastrocnemius; H 2 O 2 : hydrogen peroxide; IMF: intermyofibrillar; LAMP1: lysosomal associated membrane protein 1; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; mKO: skeletal muscle-specific knockout; MMA: monomethylarginine; MTOR: mechanistic target of rapamycin kinase; MYH: myosin heavy chain; NFE2L2/NRF2: NFE2 like bZIP transcription factor 2; OXPHOS: oxidative phosphorylation; PABPC1/PABP1: poly(A) binding protein cytoplasmic 1; PPARGC1A/PGC-1α: PPARG coactivator 1 alpha; PRKN/parkin: parkin RBR E3 ubiquitin protein ligase; PRMT: protein arginine methyltransferase; Sal: saline; SDMA: symmetric dimethylarginine; SIRT1: sirtuin 1; SKP2: S-phase kinase associated protein 2; SMARCC1/BAF155: SWI/SNF related, matrix associated, actin dependent regulator of chromatin subfamily c member 1; SOL: soleus; SQSTM1/p62: sequestosome 1; SS: subsarcolemmal; TA: tibialis anterior; TFAM: transcription factor A, mitochondrial; TFEB: transcription factor EB; TOMM20: translocase of outer mitochondrial membrane 20; TRIM63/MuRF1: tripartite motif containing 63; ULK1: unc-51 like autophagy activating kinase 1; VPS11: VPS11 core subunit of CORVET and HOPS complexes; WT: wild-type.

Mantle cell lymphoma (MCL) is an incurable and aggressive subtype of non-Hodgkin B-cell lymphoma. Increased lipid uptake, storage, and lipogenesis occur in a variety of cancers and contribute to rapid tumor growth. However, no data has been explored for the roles of lipid metabolism reprogramming in MCL. Here, we identified aberrant lipid metabolism reprogramming and PRMT5 as a key regulator of cholesterol and fatty acid metabolism reprogramming in MCL patients. High PRMT5 expression predicts adverse outcome prognosis in 105 patients with MCL and GEO database (GSE93291). PRMT5 deficiency resulted in proliferation defects and cell death by CRISPR/Cas9 editing. Moreover, PRMT5 inhibitors including SH3765 and EPZ015666 worked through blocking SREBP1/2 and FASN expression in MCL. Furthermore, PRMT5 was significantly associated with MYC expression in 105 MCL samples and the GEO database (GSE93291). CRISPR MYC knockout indicated PRMT5 can promote MCL outgrowth by inducing SREBP1/2 and FASN expression through the MYC pathway., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bacterial pore-forming toxins (PFTs) that disrupt host plasma membrane integrity (PMI) significantly contribute to the virulence of various pathogens. However, how host cells protect PMI in response to PFT perforation in vivo remains obscure. Previously, we demonstrated that the HLH-30/TFEB-dependent intrinsic cellular defense (INCED) is elicited by PFT to maintain PMI in Caenorhabditis elegans intestinal epithelium. Yet, the molecular mechanism for the full activation of HLH-30/TFEB by PFT remains elusive. Here, we reveal that PRMT-7 (protein arginine methyltransferase-7) is indispensable to the nuclear transactivation of HLH-30 elicited by PFTs. We demonstrate that PRMT-7 participates in the methylation of HLH-30 on its RAG complex binding domain to facilitate its nuclear localization and activation. Moreover, we showed that PRMT7 is evolutionarily conserved to regulate TFEB cellular localization and repair plasma damage caused by PFTs in human intestinal cells. Together, our observations not only unveil a novel PRMT-7/PRMT7-dependent post-translational regulation of HLH-30/TFEB but also shed insight on the evolutionarily conserved mechanism of the INCED against PFT in metazoans.

Procaspase-8 is a key mediator of death receptor (DR)-mediated pathways. Recently, the role of post-translational modifications (PTMs) of procaspase-8 in controlling cell death has received increasing attention. Here, using mass spectrometry screening, pharmacological inhibition and biochemical assays, we show that procaspase-8 can be targeted by the PRMT5/RIOK1/WD45 methylosome complex. Furthermore, two potential methylation sites of PRMT5 on procaspase-8, R233 and R435, were identified in silico. R233 and R435 are highly conserved in mammals and their point mutations are among the most common mutations of caspase-8 in cancer. The introduction of mutations at these positions resulted in inhibitory effects on CD95L-induced caspase-8 activity, effector caspase activation and apoptosis. In addition, we show that procaspase-8 can undergo symmetric di-methylation. Finally, the pharmacological inhibition of PRMT5 resulted in the inhibitory effects on caspase activity and apoptotic cell death. Taken together, we have unraveled the additional control checkpoint in procaspase-8 activation and the arginine methylation network in the extrinsic apoptosis pathway., (© 2024. The Author(s).)

Protein arginine methyltransferase (PRMT) 2 catalyzes the methylation of arginine residues in histones. Depression is associated with histone methylation; however, more comprehensive research is needed on how PRMT2 regulates depression. The present study aimed to investigate the effects and possible mechanism(s) of PRMT2 overexpression on depression-like behavior induced by chronic unpredictable mild stress (CUMS) in rats, and whether lentivirus-mediated PRMT2 overexpression in the hippocampus suppresses depression-like behavior. Furthermore, the PRMT2 inhibitor MS023 was administered to the animals to investigate whether the antidepressant effect of PRMT2 overexpression could be reversed. Behavioral experiments were performed to detect depression-like behavior in rats. Western blotting was used to determine protein expression levels of PRMT2, histone H3R8 asymmetric dimethylation (H3R8me2a), inducible nitric oxide synthase (iNOS), and arginase 1 (Arg1) in rat hippocampal tissues. Hippocampal microglia and PRMT2 were stained using immunofluorescence techniques. Enzyme-linked immunosorbent assay was used to determine the levels of various inflammatory factors in rat hippocampal tissue. Results of analysis revealed that PRMT2 overexpression in the hippocampus exerted an antidepressant effect. PRMT2 overexpression in the hippocampus reduced the proportion of activated microglia in the hippocampus, upregulated Arg1 and H3R8me2a expression, and downregulated iNOS expression. PRMT2 overexpression in the hippocampus inhibited the release of pro-inflammatory factors and promoted the release of anti-inflammatory factors. In summary, PRMT2 overexpression in the hippocampus promoted the conversion of microglia from the M1 to M2 type, resulting in an antidepressant effect. These results suggest that PRMT2 may be a potential therapeutic target to prevent and treat depression., Competing Interests: Declaration of competing interest None of the authors have any conflicts of interests related to this work., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The tumor necrosis factor α-induced protein 8 (TIPE, also TNFAIP8 or OXi-α) family is a newly discovered series of proteins involved in immune regulation and tumorigenesis. TIPE1, a member of the TIPE/TNFAIP8/OXi-α family, has emerged as an anticancer-drug target, as it promotes cancer cell apoptosis and inhibits cell proliferation. The current study aimed to systematically reveal that TIPE1 regulates the activity of protein arginine methyltransferase (PRMT)-1 and the subsequent methylation of signal transducer and activator of transcription (STAT)-3 to suppress oral squamous cell carcinoma (OSCC) growth. TIPE1 was down-regulated in the OSCC cell lines (Tca8113, SCC25, Cal27, SCC15, and HSC27). TIPE1 overexpression significantly inhibited cell proliferation, colony formation, in vivo tumorgenicity, and Ki-67 expression in OSCC. TIPE1 interacted with the catalytic region of PRMT1 and inhibited STAT3 methylation. The effects of TIPE1 on OSCC cells were alleviated after PRMT1 overexpression, confirming the importance of this interaction to the tumor-suppressive effects of TIPE1. Together, these findings confirmed that TIPE1 mediated PRMT1 suppression through direct binding to its catalytic domain and subsequently inhibited the methylation and expression of STAT3 in OSCC cells, thereby inhibiting cell growth and tumorgenicity., (Copyright © 2024 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Alzheimer's disease (AD) is the leading cause of mortality, disability, and long-term care burden in the United States, with women comprising the majority of AD diagnoses. While AD-related dementia is associated with tau and amyloid beta accumulation, concurrent derangements in cerebral blood flow have been observed alongside these proteinopathies in humans and rodent models. The homeostatic production of nitric oxide synthases (NOS) becomes uncoupled in AD which leads to decreased NO-mediated vasodilation and oxidative stress via the production of peroxynitrite (ONOO-∙) superoxide species. Here, we investigate the role of the novel protein arginine methyltransferase 4 (PRMT4) enzyme function and its downstream product asymmetric dimethyl arginine (ADMA) as it relates to NOS dysregulation and cerebral blood flow in AD. ADMA (type-1 PRMT product) has been shown to bind NOS as a noncanonic ligand causing enzymatic dysfunction. Our results from RT-qPCR and protein analyses suggest that aged (9-12 months) female mice bearing tau- and amyloid beta-producing transgenic mutations (3xTg-AD) express higher levels of PRMT4 in the hippocampus when compared to age- and sex-matched C57BL6/J mice. In addition, we performed studies to quantify the expression and activity of different NOS isoforms. Furthermore, laser speckle contrast imaging analysis was indicative that 3xTg-AD mice have dysfunctional NOS activity, resulting in reduced production of NO metabolites, enhanced production of free-radical ONOO-, and decreased cerebral blood flow. Notably, the aforementioned phenomena can be reversed via pharmacologic PRMT4 inhibition. Together, these findings implicate the potential importance of PRMT4 signaling in the pathogenesis of Alzheimer's-related cerebrovascular derangement., (© 2022 The Authors. Journal of Cellular Physiology published by Wiley Periodicals LLC.)

Arginine methylation is a protein posttranslational modification important for the development of skeletal muscle mass and function. Despite this, our understanding of the regulation of arginine methylation under settings of health and disease remains largely undefined. Here, we investigated the regulation of arginine methylation in skeletal muscles in response to exercise and hypertrophic growth, and in diseases involving metabolic dysfunction and atrophy. We report a limited regulation of arginine methylation under physiological settings that promote muscle health, such as during growth and acute exercise, nor in disease models of insulin resistance. In contrast, we saw a significant remodeling of asymmetric dimethylation in models of atrophy characterized by the loss of innervation, including in muscle biopsies from patients with myotrophic lateral sclerosis (ALS). Mass spectrometry-based quantification of the proteome and asymmetric arginine dimethylome of skeletal muscle from individuals with ALS revealed the largest compendium of protein changes with the identification of 793 regulated proteins, and novel site-specific changes in asymmetric dimethyl arginine (aDMA) of key sarcomeric and cytoskeletal proteins. Finally, we show that in vivo overexpression of PRMT1 and aDMA resulted in increased fatigue resistance and functional recovery in mice. Our study provides evidence for asymmetric dimethylation as a regulator of muscle pathophysiology and presents a valuable proteomics resource and rationale for numerous methylated and nonmethylated proteins, including PRMT1, to be pursued for therapeutic development in ALS., (© 2024 Federation of American Societies for Experimental Biology.)

Microglia-mediated inflammatory response is one key cause of many central nervous system diseases, like Alzheimer's disease. We hypothesized that a novel C15orf39 (MAPK1 substrate) plays a critical role in the microglial inflammatory response. To confirm this hypothesis, we used lipopolysaccharide (LPS)-and interferon-gamma (IFN-γ)-induced human microglia HMC3 cells as a representative indicator of the microglial in vitro inflammatory response. We found that C15orf39 was down-regulated when interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα) expression increased in LPS/IFN-γ-stimulated HMC3 cells. Once C15orf39 was overexpressed, IL-6 and TNFα expression were reduced in LPS/IFN-γ-stimulated HMC3 cells. In contrast, C15orf39 knockdown promoted IL-6 and TNFα expression in LPS/IFN-γ-stimulated HMC3 cells. These results suggest that C15orf39 is a suppressive factor in the microglial inflammatory response. Mechanistically, C15orf39 interacts with the cytoplasmic protein arginine methyltransferase 2 (PRMT2). Thus, we termed C15orf39 a PRMT2 interaction protein (PRMT2 IP). Furthermore, the interaction of C15orf39 and PRMT2 suppressed the activation of NF-κB signaling via the PRMT2-IκBα signaling axis, which then led to a reduction in transcription of the inflammatory factors IL6 and TNF-α. Under inflammatory conditions, NF-κBp65 was found to be activated and to suppress C15orf39 promoter activation, after which it canceled the suppressive effect of the C15orf39-PRMT2-IκBα signaling axis on IL-6 and TNFα transcriptional expression. In conclusion, our findings demonstrate that in a steady condition, the interaction of C15orf39 and PRMT2 stabilizes IκBα to inhibit IL-6 and TNFα expression by suppressing NF-κB signaling, which reversely suppresses C15orf39 transcription to enhance IL-6 and TNFα expression in the microglial inflammatory condition. Our study provides a clue as to the role of C15orf39 in microglia-mediated inflammation, suggesting the potential therapeutic efficacy of C15orf39 in some central nervous system diseases.

Arabidopsis (Arabidopsis thaliana) PROTEIN ARGININE METHYLTRANSFERASE5 (PRMT5) post-translationally modifies RNA-binding proteins by arginine (R) methylation. However, the impact of this modification on the regulation of RNA processing is largely unknown. We used the spliceosome component, SM-LIKE PROTEIN 4 (LSM4), as a paradigm to study the role of R-methylation in RNA processing. We found that LSM4 regulates alternative splicing (AS) of a suite of its in vivo targets identified here. The lsm4 and prmt5 mutants show a considerable overlap of genes with altered AS raising the possibility that splicing of those genes could be regulated by PRMT5-dependent LSM4 methylation. Indeed, LSM4 methylation impacts AS, particularly of genes linked with stress response. Wild-type LSM4 and an unmethylable version complement the lsm4-1 mutant, suggesting that methylation is not critical for growth in normal environments. However, LSM4 methylation increases with abscisic acid and is necessary for plants to grow under abiotic stress. Conversely, bacterial infection reduces LSM4 methylation, and plants that express unmethylable-LSM4 are more resistant to Pseudomonas than those expressing wild-type LSM4. This tolerance correlates with decreased intron retention of immune-response genes upon infection. Taken together, this provides direct evidence that R-methylation adjusts LSM4 function on pre-mRNA splicing in an antagonistic manner in response to biotic and abiotic stress., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Pancreatic ductal adenocarcinoma (PDAC) carries a dismal prognosis due to therapeutic resistance. We show that PDAC cells undergo global epigenetic reprogramming to acquire chemoresistance, a process that is driven at least in part by protein arginine methyltransferase 1 (PRMT1). Genetic or pharmacological PRMT1 inhibition impairs adaptive epigenetic reprogramming and delays acquired resistance to gemcitabine and other common chemo drugs. Mechanistically, gemcitabine treatment induces translocation of PRMT1 into the nucleus, where its enzymatic activity limits the assembly of chromatin-bound MAFF/BACH1 transcriptional complexes. Cut&Tag chromatin profiling of H3K27Ac, MAFF, and BACH1 suggests a pivotal role for MAFF/BACH1 in global epigenetic response to gemcitabine, which is confirmed by genetically silencing MAFF. PRMT1 and MAFF/BACH1 signature genes identified by Cut&Tag analysis distinguish gemcitabine-resistant from gemcitabine-sensitive patient-derived xenografts of PDAC, supporting the PRMT1-MAFF/BACH1 epigenetic regulatory axis as a potential therapeutic avenue for improving the efficacy and durability of chemotherapies in patients of PDAC., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma. The oncogene product Tax of HTLV-I is thought to play crucial roles in leukemogenesis by promoting proliferation of the virus-infected cells through activation of growth-promoting genes. These genes code for growth factors and their receptors, cytokines, cell adhesion molecules, growth signal transducers, transcription factors and cell cycle regulators. We show here that Tax activates the gene coding for coactivator-associated arginine methyltransferase 1 (CARM1), which epigenetically enhances gene expression through methylation of histones. Tax activated the Carm1 gene and increased protein expression, not only in human T-cell lines but also in normal peripheral blood lymphocytes (PHA-PBLs). Tax increased R17-methylated histone H3 on the target gene IL-2Rα , concomitant with increased expression of CARM1. Short hairpin RNA (shRNA)-mediated knockdown of CARM1 decreased Tax-mediated induction of IL-2Rα and Cyclin D2 gene expression, reduced E2F activation and inhibited cell cycle progression. Tax acted via response elements in intron 1 of the Carm1 gene, through the NF-κB pathway. These results suggest that Tax-mediated activation of the Carm1 gene contributes to leukemogenic target-gene expression and cell cycle progression, identifying the first epigenetic target gene for Tax-mediated trans-activation in cell growth promotion.

Background: The dysregulation of Isocitrate dehydrogenase (IDH) and the subsequent production of 2-Hydroxyglutrate (2HG) may alter the expression of epigenetic proteins in Grade 4 astrocytoma. The interplay mechanism between IDH, O-6-methylguanine-DNA methyltransferase ( MGMT) -promoter methylation, and protein methyltransferase proteins-5 ( PRMT5) activity, with tumor progression has never been described., Methods: A retrospective cohort of 34 patients with G4 astrocytoma is classified into IDH-mutant and IDH-wildtype tumors. Both groups were tested for MGMT -promoter methylation and PRMT5 through methylation-specific and gene expression PCR analysis. Inter-cohort statistical significance was evaluated., Results: Both IDH-mutant WHO grade 4 astrocytomas (n = 22, 64.7%) and IDH-wildtype glioblastomas (n = 12, 35.3%) had upregulated PRMT5 gene expression except in one case. Out of the 22 IDH-mutant tumors, 10 (45.5%) tumors showed MGMT -promoter methylation and 12 (54.5%) tumors had unmethylated MGMT . All IDH-wildtype tumors had unmethylated MGMT . There was a statistically significant relationship between MGMT -promoter methylation and IDH in G4 astrocytoma ( p -value = 0.006). Statistically significant differences in progression-free survival (PFS) were also observed among all G4 astrocytomas that expressed PRMT5 and received either temozolomide (TMZ) or TMZ plus other chemotherapies, regardless of their IDH or MGMT -methylation status ( p -value=0.0014). Specifically, IDH-mutant tumors that had upregulated PRMT5 activity and MGMT -promoter methylation, who received only TMZ, have exhibited longer PFS., Conclusions: The relationship between PRMT5 , MGMT -promoter, and IDH is not tri-directional. However, accumulation of D2-hydroxyglutarate (2-HG), which partially activates 2-OG-dependent deoxygenase, may not affect their activities. In IDH-wildtype glioblastomas, the 2HG-2OG pathway is typically inactive, leading to PRMT5 upregulation. TMZ alone, compared to TMZ-plus, can increase PFS in upregulated PRMT5 tumors. Thus, using a PRMT5 inhibitor in G4 astrocytomas may help in tumor regression., Competing Interests: The authors have no relevant conflict of interest to disclose., (© 2024 Kurdi et al.)