Arginine Methylation: The Coming of Age

Protein Arginine Methyltransferases from Regulatory Function to Clinical Implication in Central Nervous System

Arginine methylation, catalyzed by protein arginine methyltransferases (PRMTs), is a regulatory key mechanism involved in various cellular processes such as gene expression, RNA processing, DNA damage repair. Increasing evidence highlights the crucial role of PRMTs in human diseases, including cancer, cardiovascular and metabolic diseases. Here, this review focuses on the latest findings regarding PRMTs in the central nervous system (CNS), emphasizing their regulatory roles in neural stem cells, neurons, and glial cells. Additionally, we examine the connection between PRMTs dysregulation and neurological diseases affecting the CNS, including brain tumors, neurodegenerative diseases, and neurodevelopmental disorders. Therefore, this review aims to deepen our understanding of PRMTs-mediated arginine methylation in CNS and open avenues for developing novel therapeutic strategies for neurological diseases.

Arginine methylation modulates tumor fate and prognosis in clear cell renal cell carcinoma

BACKGROUND

Arginine methylation, a key post-translational modification, plays a pivotal role in regulating various cellular processes and has been implicated in cancer progression. However, the potential of arginine methylation-related genes as prognostic markers in clear cell renal cell carcinoma (ccRCC) remains underexplored.

METHODS

We utilized public transcriptomic datasets from TCGA, E-MTAB-1980 and ICGC, for model construction and validation. Single-cell RNA sequencing datasets were employed to evaluate gene expression patterns at the cellular level. Consensus clustering, KM survival analysis, and GSVA were applied to identify molecular subtypes and related pathways. Univariate and multivariate Cox regression analyses were applied to develop an arginine methylation-related signature (AMS). Immune profiling, mutation landscape, and drug sensitivity prediction were also employed to explore the model's association with clinical features, immune infiltration, mutation burden, and therapeutic responses.

RESULTS

The AMS demonstrated robust prognostic performance, with consistent validation across external cohorts. High-risk patients exhibited significantly worse survival, elevated TMB, and an immunosuppressive tumor microenvironment characterized by increased infiltration of regulatory immune cells. Single-cell RNA sequencing revealed key prognostic genes expressed predominantly in cancer and immune cells, supporting their role in tumor progression and immune interactions.

CONCLUSION

The arginine methylation-based prognostic model provides a reliable framework for survival risk stratification in ccRCC and holds promise for guiding personalized therapeutic strategies. Future research should emphasize clinical validation of this model and explore its potential role in optimizing immunotherapy and targeted treatment strategies for ccRCC.

Current knowledge on the mechanisms underpinning vasculogenic mimicry in triple negative breast cancer and the emerging role of nitric oxide

Vasculogenic mimicry (VM) is the process by which cancer cells form vascular-like channels to support their growth and dissemination. These channels lack endothelial cells and are instead lined by the tumour cells themselves. VM was first reported in uveal melanomas but has since been associated with other aggressive solid tumours, such as triple-negative breast cancer (TNBC). In TNBC patients, VM is associated with tumour aggressiveness, drug resistance, metastatic burden, and poor prognosis. The lack of effective targeted therapies for TNBC has stimulated research on the mechanisms underpinning VM in order to identify novel druggable targets. In recent years, studies have highlighted the role of nitric oxide (NO), the NO synthesis inhibitor, asymmetric dimethylarginine (ADMA), and dimethylarginine dimethylaminohydrolase 1 (DDAH1), the key enzyme responsible for ADMA metabolism, in regulating VM. Specifically, NO inhibition through downregulation of DDAH1 and consequent accumulation of ADMA appears to be a promising strategy to suppress VM in TNBC. This review discusses the current knowledge regarding the molecular pathways underpinning VM in TNBC, anti-VM therapies under investigation, and the emerging role of NO regulation in VM.

Role of histone methylation in insect development: KMT5A regulates ecdysteroid biosynthesis during metamorphosis of Tribolium castaneum

Methylation levels of core histones play important roles in the regulation of gene expression and impact animal development. However, the methyltransferases and demethylases that determine histone methylation levels remain largely unexplored in insects. Most of our current understanding of histone methylation comes from mammalian studies. In this study, we first identified potential histone methyltransferases and demethylases encoded in the genome of the red flour beetle Tribolium castaneum. The function of these histone methylation enzymes in the metamorphosis was investigated by knocking down genes coding for these enzymes using RNA interference (RNAi). Our results showed that a lysine methyltransferase, KMT5A, plays a critical role in T. castaneum metamorphosis by regulating the biosynthesis of ecdysteroids. Treating KMT5A-knockdown larvae with 20 hydroxyecdysone can partially rescue T. castaneum pupation. Western blot analysis showed that KMT5A catalyzes H4K20 mono-methylation. However, further studies suggest that KMT5A may regulate T. castaneum pupation through mechanisms independent of H4K20 methylation. These data uncovered the roles of histone methylation enzymes in T. castaneum metamorphosis and KMT5A as a critical regulator of ecdysteroid biosynthesis.

miR-205-3p inhibits porphyromonas gingivalis lipopolysaccharide-induced human umbilical vein endothelial cells inflammation and apoptosis by targeting PRMT5

OBJECTIVE

This study aimed to investigate the regulatory mechanism of miR-205-3p in Porphyromonas gingivalis lipopolysaccharide (P.g-LPS)-induced atherosclerosis.

DESIGN

In an in vitro setting, human umbilical vein endothelial cells (HUVECs) were exposed to P.g-LPS to simulate the vascular endothelial damage induced by periodontitis. Subsequently, ELISA and flow cytometry were employed to assess the inflammatory response and apoptotic status of these cells.To quantify the expression levels of protein arginine methyltransferase 5 (PRMT5), BCL2-associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), P65 and miR-205-3p within the HUVECs, Western Blot and qPCR were respectively utilized. Moreover, small interfering RNA (siRNA) targeting PRMT5 and miR-205-3p were applied to monitor the changes in PRMT5 expression. Bioinformatics analysis was carried out to predict the potential binding sites between miR-205-3p and PRMT5. Finally, the interaction between miR-205-3p and PRMT5 was validated through the dual-luciferase reporter assay.

RESULTS

The results indicate that P.g-LPS intervention exacerbates damage to HUVECs and increases the expression of PRMT5. Silencing PRMT5 reduces cell inflammation and apoptosis. After stimulation with P.g-LPS, the level of miR-205-3p decreases, and its overexpression alleviates inflammation and apoptosis in the cells. Bioinformatics analysis and dual luciferase reporter assays confirm that PRMT5 is a target of miR-205-3p, and the overexpression of PRMT5 can reverse the protective effects of miR-205-3p.

CONCLUSION

miR-205-3p can mitigate vascular endothelial injury by decreasing PRMT5 expression, providing new insights for potential treatments.

BRD9 functions as a methylarginine reader to regulate AKT-EZH2 signaling

Recognition of methylarginine marks by effector proteins ("readers") is a critical link between arginine methylation and various cellular processes. Recently, we identified methylation of AKT1 at arginine-391 (R391), but the reader for this methylation has yet to be characterized. Here, we show that bromodomain-containing protein 9 (BRD9), a reader of acetylated lysine, unexpectedly recognizes methylated R391 of AKT1 through an aromatic cage in its bromodomain. Disrupting the methylarginine reader function of BRD9 suppresses AKT activation and tumorigenesis. RNA sequencing data show that BRD9 and AKT coregulate a hallmark transcriptional program in part through enhancer of zeste homolog 2 (EZH2)-mediated methylation of histone-3 lysine-27. We also find that inhibitors of BRD9 and EZH2 display synergistic effects on suppression of cell proliferation and tumor growth. Collectively, our study reveals a previously unknown function of BRD9 and a potential therapeutic strategy for cancer treatment by combining BRD9 and EZH2 inhibitors.

Regulation of protein arginine methyltransferase in osteoporosis: a narrative review

Osteoporosis (OP), a systemic bone disease characterised by increased bone fragility and susceptibility to fracture, is mainly caused by a decline in bone mineral density (BMD) and quality caused by an imbalance between bone formation and resorption. Protein arginine methyltransferases (PRMTs) are epigenetic factors and post-translational modification (PTM) enzymes participating in various biological processes, including mRNA splicing, DNA damage repair, transcriptional regulation, and cell signalling. They act by catalysing the transfer and modification of arginine residues and, thus, have become therapeutic targets for OP. In-depth studies have found that these enzymes also play key roles in bone matrix protein metabolism, skeletal cell proliferation and differentiation, and signal pathway regulation to regulate bone formation, bone resorption balance, or both and jointly maintain bone health and stability. However, the expression changes and mechanisms of action of multiple members of the PRMT family differ in OP. Therefore, this paper discusses the biological functions, mechanisms of action, and influencing factors of PRMTs in OP, which is expected to provide a new understanding of the pathogenesis of OP. Furthermore, we present theoretical support for the development of more precise and effective treatment strategies as well as for further study of the molecular mechanisms of PRMTs.

The expression of PRMT5 is associated with postoperative chemotherapeutic outcome in colon cancer

BACKGROUND

Postoperative chemotherapy is an essential treatment in locally advanced colon cancer, however, effective biomarkers for predicting patients who will benefit from this therapy are lacking. This study aims to explore the clinical value of protein arginine methyltransferase 5 (PRMT5) in guiding adjuvant chemotherapy in patients with colon cancer.

METHODS

PRMT5 expression was determined via immunohistochemistry (IHC) in tumor and paratumor samples from 199 colon cancer patients who underwent radical surgery. The correlation between PRMT5 expression and clinicopathological parameters, as well as clinical outcomes, was subsequently investigated.

RESULTS

The protein expression levels of PRMT5 were significantly elevated in colon cancer tissues compared to paratumor tissues (P < 0.01). However, the expression of PRMT5 in colon cancer did not show a significant association with various clinicopathological parameters, including sex, age, tumor location, histological differentiation, TNM stage, vascular invasion, or microsatellite status. Notably, a strong correlation was observed between PRMT5 expression and adjuvant therapeutic outcomes: patients with high PRMT5 expression exhibited a lower 5-year disease-free survival (DFS) rate compared to those with low PRMT5 expression within the chemotherapy group (50% vs. 67.2%, P = 0.039). In contrast, PRMT5 expression did not correlate with clinical outcomes in the non-chemotherapy group. Furthermore, multivariate analysis indicated that PRMT5 expression, along with N stage and microsatellite status, served as independent risk factors for 5-year DFS in patients undergoing adjuvant chemotherapy.

CONCLUSION

This study highlights PRMT5 as a prognostic marker for adjuvant chemotherapy in patients with colon cancer. The findings suggest that PRMT5 expression may serve as an important predictor of therapeutic outcomes, providing valuable insights for clinical decision-making and personalized treatment strategies.

The Histone Methyltransferase PRMT5 Mediates the Epigenetic Modification to Modulate High Temperatures and Tea Quality in Tea Plants (Camellia sinensis)

High temperatures significantly affect tea yield and quality. Arginine methylation is crucial for plant growth and environmental adaptation. However, its role in regulating plant responses to high temperatures remains unclear. In this study, we identified an important Type II arginine methyltransferase, PRMT5, in tea plants and confirmed its methyltransferase activity both in vivo and in vitro. Our findings revealed that CsPRMT5-mediated symmetric dimethylation of histone H4R3 (H4R3sme2) was markedly reduced under high-temperature conditions in tea plants. Both the inhibitor and gene-silencing approaches led to decreased levels of H4R3sme2 modification, resulting in alterations in theanine and catechins. We employed a genome-wide approach to analyze the RNA sequencing (RNA-seq) of tea plants subjected to ambient high temperatures, PRMT5 inhibitors, and PRMT5 silencing, along with H4R3sme2 and CsPRMT5 chromatin immunoprecipitation sequencing (ChIP-seq). Comparative analysis of these datasets indicated that genes regulated by H4R3sme2 were predominantly enriched within the reactive oxygen species (ROS), calcium ion, and hormone signalling pathways under elevated temperature conditions. Furthermore, we validated CsCDPK9 as a target gene regulated by H4R3sme2 and found that silencing CsCDPK9 resulted in increased theanine content and decreased catechin content at high temperatures. Our findings suggest that CsPRMT5-mediated H4R3sme2 plays a pivotal role in the growth of tea plants, as well as in their adaptability to fluctuations in ambient temperatures. This study provides new insights into breeding strategies aimed at developing crops that are better equipped to withstand environmental changes induced by climate change.

Hypoxia-induced PRMT1 methylates HIF2β to promote breast tumorigenesis via enhancing glycolytic gene transcription

Hypoxia-induced metabolic reprogramming is closely linked to breast cancer progression. Through transcriptomic analysis, we identified PRMT1 as a direct target of hypoxia-inducible factor 1α (HIF1α) under hypoxic conditions in breast cancer cells. In turn, PRMT1 enhances the expression of HIF1α-driven glycolytic genes. Mechanistically, PRMT1 methylates HIF2β at arginine 42, facilitating the formation, chromatin binding, and the transcriptional activity of the HIF1α/HIF2β heterodimer. Genetic and pharmacological inhibition of PRMT1 suppresses HIF2β methylation, HIF1α/HIF2β heterodimer formation, chromatin binding, glycolytic gene expression, lactate production, and the malignant behaviors of breast cancer cells. Moreover, combination treatment with iPRMT1, a PRMT1 inhibitor, and menadione, an HIF1α/P300 interaction inhibitor, demonstrates synergistic effects in suppressing breast tumor growth. Clinically, PRMT1 and PRMT1-mediated HIF2β methylation were significantly elevated in breast tumors compared with adjacent normal tissues. In conclusion, our findings reveal the critical role of PRMT1-mediated arginine methylation in glycolytic gene expression, metabolic reprogramming, and breast tumor growth.

The mRNA export pathway licenses viral mimicry response and antitumor immunity by actively exporting nuclear retroelement transcripts

Nuclear retroelement transcripts (RTs), which can be elicited both transcriptionally and posttranscriptionally, form double-stranded RNA (dsRNA) in cytosol to trigger the viral mimicry response (VMR) and antitumor immunity. However, the strength of the induced VMR varies tremendously across tumor types, and the underlying mechanisms remain poorly understood. Here, we demonstrate that the mRNA export pathway modulates the VMR through actively exporting nuclear RTs for cytosolic dsRNA formation after their induction. Tumor cells hijack this process for immune evasion through aberrant coactivator-associated arginine methyltransferase 1 (CARM1) expression. Mechanistically, we show that the cytoplasmic transportation of RTs by the mRNA export pathway is counteracted by the RNA exosome, which cleaves multiple transcripts within this pathway, including those encoding the essential DExD-box helicase 39A (DDX39A) and the adaptor protein ALYREF. CARM1 enhances the RNA exosome activity to attenuate the nuclear export of RTs by the mRNA export pathway through two synergistic mechanisms: (i) transcriptionally activating several RNA exosome components and (ii) posttranslationally methylating arginine 6 of the RNA exosome subunit EXOSC1, which protects it from proteasome-mediated degradation. Collectively, our study highlights the critical active regulatory role of the mRNA export pathway in transporting nuclear RTs into the cytosol for triggering the VMR and tumor immunity. Furthermore, we propose that enhancing the mRNA export pathway activity, either through CARM1 inhibition or RNA exosome modulation, could reinforce the therapeutic agent-induced VMR, thus holding the promise for overcoming tumor immune evasion and immunotherapy resistance.

Dietary advanced glycation end-products exacerbate sarcopenia onset by activating apoptosis through PRMT1-mediated CRTC3 arginine methylation

BACKGROUND

Sarcopenia, the age-related decline in muscle mass and function, poses a major health risk to the elderly population. Although dietary advanced glycation end-products (AGEs) have been implicated in worsening sarcopenia, the precise molecular mechanisms remain unclear.

METHODS

A sarcopenia animal model was established by feeding a high AGE diet to C57BL/6 mice. Muscle function and mass were assessed using grip strength tests, and rotarod tests. Proteomic analysis was used to identify differentially expressed proteins. Immunoprecipitation, mass spectrometry, and co-immunoprecipitation were employed to investigate protein interactions both in vivo and in vitro. Quantitative reverse transcription PCR and Western blotting were conducted to measure gene and protein expression levels.

RESULTS

Our results revealed that dietary AGEs accelerated the onset of sarcopenia in mice by triggering apoptosis. Proteomic analysis showed a marked upregulation of protein arginine methyltransferase 1 (PRMT1) in the muscle tissues of mice fed a high AGE diet. PRMT1 mediated the arginine methylation of CREB-regulated transcription coactivator 3 (CRTC3) at the R534 site within its transactivation domain, leading to CRTC3 activation. The activated CRTC3, together with Forkhead box O3a (FOXO3a), transactivated the BAX (BCL2 associated X) gene, initiating Bax downstream signaling, promoting apoptosis in muscle cells, and contributing to muscle atrophy. Inhibition of PRMT1 prevented CRTC3 methylation and suppressed Bax-mediated apoptotic signaling in vitro. Moreover, in vivo treatment with PRMT1 and Bax inhibitors significantly attenuated AGE-induced sarcopenia in mice.

CONCLUSION

PRMT1-mediated CRTC3 arginine methylation plays a critical role in AGE-induced sarcopenia and suggests potential therapeutic targets for preventing sarcopenia progression.

Impact of sevoflurane anesthesia on S-adenosylmethionine in neonates under general anesthesia

Background and Aims

Preclinical studies in rodents and primates have shown that anesthesia was neurotoxic to the developing brain after exposure in the neonatal period. Sevoflurane a commonly used inhalational anesthetic, especially in pediatric surgery, might cause behavioral impairment in the developing brain. Although favored for its rapid onset and minimal airway disturbance, sevoflurane has been implicated in neurotoxic effects such as anesthesia-induced developmental neurotoxicity in rodents, through various mechanisms. One of the mechanisms was disturbances in methylation metabolism which can be easily treated if it is proved. This study aims to evaluate the levels of S-adenosylmethionine [SAM] following sevoflurane anesthesia in neonates and to correlate the duration of sevoflurane exposure and S-adenosylmethionine levels.

Material and Methods

Sixty neonates were included in the study under general anesthesia. Pre- and postsevoflurane exposure arterial blood samples were collected in ethylenediamine tetraacetic acid vacutainers. Each sample was centrifuged at 1000 rpm for 10 min. Plasma was separated and stored at -80°C, then subjected to S-adenosylmethionine enzyme-linked immunoassay test for preand postsevoflurane exposure levels of SAM.

Results

The difference between the pre- and post-SAM values is not statistically significant and also with increasing the duration of sevoflurane exposure there was no reduction in the SAM levels (r = 0.17), and the correlation was not significant (P = 0.18).

Conclusion

Single exposure to sevoflurane does not impact SAM levels in neonates undergoing general anesthesia.

β-hydroxybutyrylation and O-GlcNAc modifications of STAT1 modulate antiviral defense in aging

Aging changes the protein activity status to affect the body's functions. However, how aging regulates protein posttranslational modifications (PTMs) to modulate the antiviral defense ability of the body remains unclear. Here, we found that aging promotes STAT1 β-hydroxybutyrylation (Kbhb) at Lys592, which inhibits the interaction between STAT1 and type-I interferon (IFN-I) receptor 2 (IFNAR2), thereby attenuating IFN-I-mediated antiviral defense activity. Additionally, we discovered that a small molecule from a plant source, hydroxy camptothecine, can effectively reduce the level of STAT1 Kbhb, thus increasing antiviral defense ability in vivo. Further studies revealed that STAT1 O-GlcNAc modifications at Thr699 block CBP-induced STAT1 Kbhb. Importantly, fructose can improve IFN-I antiviral defense activity by orchestrating STAT1 O-GlcNAc and Kbhb modifications. This study reveals the significance of the switch between STAT1 Kbhb and O-GlcNAc modifications in regulating IFN-I antiviral immunity during aging and provides potential strategies to improve the body's antiviral defense ability in elderly individuals.

Deficiency of MTAP Is Frequent and Mostly Homogeneous in Pancreatic Ductal Adenocarcinomas

BACKGROUND

The complete loss of S-methyl-5'-thioadenosine phosphorylase (MTAP) expression, often due to homozygous 9p21 deletion, creates a druggable vulnerability in cancer cells.

METHODS

A total of 769 primary pancreatic ductal adenocarcinomas were analyzed on tissue microarrays with MTAP immunohistochemistry (IHC) and 9p21 fluorescence in situ hybridization (FISH). Intratumoral heterogeneity was assessed on a "heterogeneity" TMA containing up to nine samples from different areas of 236 primary tumor and nodal metastases, and whole sections of all tumor blocks from 19 cancers.

RESULTS

MTAP expression loss was found in 181 (37.9%) of 478 interpretable primary tumors and was unrelated to pT, pN, grade, and tumor size. MTAP expression loss was homogenous in 37.6% and heterogeneous in 1.1% of the 181 tumors, with at least three evaluable samples on the heterogeneity TMA. On whole sections, 1 of 19 tumors showed heterogeneous MTAP loss. The correlation between IHC and FISH was nearly perfect, with 98.8% of MTAP-deficient samples showing a 9p21 deletion.

CONCLUSIONS

MTAP expression loss is frequent, caused by homozygous deletion, and mostly homogeneous in pancreatic ductal adenocarcinomas. Considering also their aggressive clinical behavior, pancreatic adenocarcinomas may represent an ideal cancer type for studying new drugs targeting MTAP-deficient cancer cells in clinical trials.

From DNA-Encoded Library Screening to : An MTA-Cooperative PRMT5 Inhibitor with Potent Oral In Vivo Efficacy

Inhibition of the methyltransferase enzyme PRMT5 by MTA accumulation is a vulnerability of MTAP-deleted cancers. Herein, we report the discovery and optimization of a quinolin-2-amine DEL hit that cooperatively binds PRMT5:MEP50 and MTA to generate a catalytically inhibited ternary complex. X-ray crystallography confirms quinolin-2-amine binding of PRMT5 glutamate-444, while simultaneously exhibiting a hydrophobic interaction with MTA. Lead optimization produced AM-9747, which selectively inhibits PRMT5-directed symmetric dimethylation of arginine residues of proteins, leading to a potent reduction of cell viability in MTAP-del cells compared to MTAP-WT cells. Once-daily oral dosing of AM-9747 in mouse xenografts is well tolerated, displaying a robust and dose-dependent inhibition of symmetric dimethylation of arginine in MTAP-del tumor-xenografts and significant concomitant tumor growth inhibition without any significant effect on MTAP-WT tumor xenografts.

High PRMT5 levels, maintained by KEAP1 inhibition, drive chemoresistance in high-grade serous ovarian cancer

Protein arginine methyl transferases (PRMTs) are generally upregulated in cancers. However, the mechanisms leading to this upregulation and its biological consequences are poorly understood. Here, we identify PRMT5, the main symmetric arginine methyltransferase, as a critical driver of chemoresistance in high-grade serous ovarian cancer (HGSOC). PRMT5 levels and its enzymatic activity are induced in a platinum-resistant (Pt-resistant) state at the protein level. To reveal potential regulators of high PRMT5 protein levels, we optimized intracellular immunostaining conditions and performed unbiased CRISPR screening. We identified Kelch-like ECH-associated protein 1 (KEAP1) as a top-scoring negative regulator of PRMT5. Our mechanistic studies show that KEAP1 directly interacted with PRMT5, leading to its ubiquitin-dependent degradation under normal physiological conditions. At the genomic level, ChIP studies showed that elevated PRMT5 directly interacted with the promoters of stress response genes and positively regulated their transcription. Combined PRMT5 inhibition with Pt resulted in synergistic cellular cytotoxicity in vitro and reduced tumor growth in vivo in Pt-resistant patient-derived xenograft tumors. Overall, the findings from this study identify PRMT5 as a critical therapeutic target in Pt-resistant HGSOC cells and reveal the molecular mechanisms that lead to high PRMT5 levels in Pt-treated and chemo-resistant tumors.

The epigenetic mechanisms involved in the treatment resistance of glioblastoma

Glioblastoma (GBM) is an aggressive malignant brain tumor with almost inevitable recurrence despite multimodal management with surgical resection and radio-chemotherapy. While several genetic, proteomic, cellular, and anatomic factors interplay to drive recurrence and promote treatment resistance, the epigenetic component remains among the most versatile and heterogeneous of these factors. Herein, the epigenetic landscape of GBM refers to a myriad of modifications and processes that can alter gene expression without altering the genetic code of cancer cells. These processes encompass DNA methylation, histone modification, chromatin remodeling, and non-coding RNA molecules, all of which have been found to be implicated in augmenting the tumor's aggressive behavior and driving its resistance to therapeutics. This review aims to delve into the underlying interactions that mediate this role for each of these epigenetic components. Further, it discusses the two-way relationship between epigenetic modifications and tumor heterogeneity and plasticity, which are crucial to effectively treat GBM. Finally, we build on the previous characterization of epigenetic modifications and interactions to explore specific targets that have been investigated for the development of promising therapeutic agents.

Discovery of TNG462: A Highly Potent and Selective MTA-Cooperative PRMT5 Inhibitor to Target Cancers with MTAP Deletion

The gene encoding for MTAP is one of the most commonly deleted genes in cancer, occurring in approximately 10-15% of all human cancer. We have previously described the discovery of TNG908, a brain-penetrant clinical-stage compound that selectively targets MTAP-deleted cancer cells by binding to and inhibiting PRMT5 cooperatively with MTA, which is present in elevated concentrations in MTAP-deleted cells. Herein we describe the discovery of TNG462, a more potent and selective MTA-cooperative PRMT5 inhibitor with improved DMPK properties that is selective for MTAP-deleted cancers and is currently in Phase I/II clinical trials.

Specific sDMA modifications on the RGG/RG motif of METTL14 regulate its function in AML

BACKGROUND

Protein arginine methylations are crucial post-translational modifications (PTMs) in eukaryotes, playing a significant regulatory role in diverse biological processes. Here, we present our investigation into the detailed arginine methylation pattern of the C-terminal RG-rich region of METTL14, a key component of the m6A RNA methylation machinery, and its functional implications in biology and disease.

METHODS

Using ETD-based mass spectrometry and in vitro enzyme reactions, we uncover a specific arginine methylation pattern on METTL14. RNA methyltransferase activity assays were used to assess the impact of sDMA on METTL3:METTL14 complex activity. RNA immunoprecipitation was used to evaluate mRNA-m6A reader interactions. MeRIP-seq analysis was used to study the genome-wide effect of METTL14 sDMA on m6A modification in acute myeloid leukemia cells.

RESULTS

We demonstrate that PRMT5 catalyzes the site-specific symmetric dimethylation at R425 and R445 within the extensively methylated RGG/RG motifs of METTL14. We show a positive regulatory role of symmetric dimethylarginines (sDMA) in the catalytic efficiency of the METTL3:METTL14 complex and m6A-specific gene expression in HEK293T and acute myeloid leukemia cells, potentially through the action of m6A reader protein YTHDF1. In addition, the combined inhibition of METTL3 and PRMT5 further reduces the expression of several m6A substrate genes essential for AML proliferation, suggesting a potential therapeutic strategy for AML treatment.

CONCLUSIONS

The study confirms the coexistence of sDMA and aDMA modifications on METTL14's RGG/RG motifs, with sDMA at R425 and R445 enhancing METTL3:METTL14's catalytic efficacy and regulating gene expression through m6A deposition in cancer cells.

Interspecies interactions mediated by arginine metabolism enhance the stress tolerance of Fusobacterium nucleatum against Bifidobacterium animalis

Colorectal cancer (CRC) is a common cancer accompanied by microbiome dysbiosis. Exploration of probiotics against oncogenic microorganisms is promising for CRC treatment. Here, differential microorganisms between CRC and healthy control were analyzed. Antibacterial experiments, whole-genome sequencing, and metabolic network reconstruction were combined to reveal the anti-Fusobacterium nucleatum mechanism, which was verified by co-culture assay and mendelian randomization analysis. Sequencing results showed that F. nucleatum was enriched in CRC, yet Bifidobacterium animalis decreased gradually from healthy to CRC. Additionally, F. nucleatum could be inhibited by B. animalis. Whole-genome sequencing of B. animalis showed high phylogenetic similarity with known probiotic strains and highlighted its functions for amino acid and carbohydrate metabolism. Metabolic network reconstruction demonstrated that cross-feeding and specific metabolites (acidic molecules, arginine) had a great influence on the coexistence relationship. Finally, the arginine supplement enhanced the competitive ability of F. nucleatum against B. animalis, and the mendelian randomization and metagenomic sequencing analysis confirmed the positive relationship among F. nucleatum, arginine metabolism, and CRC. Thus, whole-genome sequencing and metabolic network reconstruction are valuable for probiotic mining and patient dietary guidance.IMPORTANCEUsing probiotics to inhibit oncogenic microorganisms (Fusobacterium nucleatum) is promising for colorectal cancer (CRC) treatment. In this study, whole-genome sequencing and metabolic network reconstruction were combined to reveal the anti-F. nucleatum mechanism of Bifidobacterium animalis, which was verified by co-culture assay and mendelian randomization analysis. The result indicated that the arginine supplement enhanced the competitive ability of F. nucleatum, which may be harmful to F. nucleatum-infected CRC patients. B. animalis is a potential probiotic to relieve this dilemma. Thus, using in silico simulation methods based on flux balance analysis, such as genome-scale metabolic reconstruction, provides valuable insights for probiotic mining and dietary guidance for cancer patients.

Metformin inhibits the histone methyltransferase CARM1 and attenuates H3 histone methylation during gluconeogenesis

Hyperglycemia is a hallmark of metabolic disorders, yet the precise mechanisms linking epigenetic regulation to glucose metabolism remain underexplored. Coactivator-associated arginine methyltransferase 1 (CARM1), a type I histone methyltransferase, promotes transcriptional activation through the methylation of histone H3 at arginine residues H3R17 and H3R26. Here, we identify a novel mechanism by which metformin, a widely prescribed antidiabetic drug, inhibits CARM1 activity. Using biochemical and biophysical assays, we show that metformin binds to the substrate-binding site of CARM1, reducing histone H3 methylation levels in CARM1-overexpressing hepatic cells and liver tissues from metformin-fed mice. This epigenetic modulation suppresses the expression of gluconeogenic enzymes (G6Pase, FBPase, and PCK1), thereby reversing CARM1-induced glycolytic suppression and regulating gluconeogenesis. Importantly, metformin does not alter CARM1 protein levels and its recruitment to gluconeogenic gene promoters but diminishes H3R17me2a marks at these loci. Our findings reveal a previously unrecognized epigenetic mechanism of metformin action, offering new therapeutic insights for hyperglycemia management.

PRMT5 Maintains Homeostasis of the Intestinal Epithelium by Modulating Cell Proliferation and Survival

Intestinal homeostasis is sustained by self-renewal of intestinal stem cells, which continuously divide and produce proliferative transit-amplifying (TA) and progenitor cells. Protein arginine methyltransferases 5 (PRMT5) plays a crucial role in regulating homeostasis of various mammalian tissues. However, its function in intestinal homeostasis remains elusive. In this study, conditional knockout of Prmt5 in the mouse intestinal epithelium leads to a reduction in stem cell population, suppression of cell proliferation, and increased cell apoptosis within the intestinal crypts, accompanied with shortened gut length, decreased mouse body weight, and eventual animal mortality. Additionally, Prmt5 deletion or its enzymatic inhibition in intestinal organoids in vitro also shows resembling cellular phenotypes. Methylome profiling identifies 90 potential Prmt5 substrates, which are involved in RNA-related biological processes and cell division. Consistently, Prmt5 depletion in intestinal organoids leads to aberrant alternative splicing in a subset of genes related to the mitotic cell cycle. Furthermore, Prmt5 loss triggers p53-mediated apoptosis in the intestinal epithelium. Collectively, the findings uncover an indispensable role of PRMT5 in promoting cell proliferation and survival, as well as maintaining stem cells in the gut epithelium.

Opto-Epigenetic Regulation of Histone Arginine Asymmetric Dimethylation via Type I Protein Arginine Methyltransferase Inhibition

Histone arginine asymmetric dimethylation, which is mainly catalyzed by type I protein arginine methyltransferases (PRMTs), is involved in broad biological and pathological processes. Recently, several type I PRMT inhibitors, such as MS023, have been developed to reverse the histone arginine dimethylation status in tumor cells, but extensive inhibition of type I PRMTs may cause side effects in normal tissues. Herein, we designed a photoactivatable MS023 prodrug (C-MS023) to achieve spatiotemporal inhibition of histone arginine asymmetric dimethylation. In vitro studies showed that C-MS023 exhibited reduced potency in inhibiting type I PRMTs. Importantly, visible light irradiation at 420 nm could trigger the photolysis of the prodrug, thereby liberating MS023 for effective downregulation of histone arginine asymmetric dimethylation and DNA replication-related transcriptomic activities. This opto-epigenetic small-molecule prodrug potentially aids in further research into the pathophysiological functions of type I PRMTs and the development of targeted epigenetic therapeutics.

MTA-Cooperative PRMT5 Inhibitors: Mechanism Switching Through Structure-Based Design

Deletion of the MTAP gene leads to accumulation of the substrate of the MTAP protein, methylthioadenosine (MTA). MTA binds PRMT5 competitively with S-adenosyl-l-methionine (SAM), and selective inhibition of the PRMT5•MTA complex relative to the PRMT5•SAM complex can lead to selective killing of cancer cells with MTAP deletion. Herein, we describe the discovery of novel compounds using structure-based drug design to switch the mechanism of binding of known, SAM-cooperative PRMT5 inhibitors to an MTA-cooperative binding mechanism by occupying the portion of the SAM binding pocket in PRMT5 that is unoccupied when MTA is bound and hydrogen bonding to Arg368, thereby allowing them to selectively target MTAP-deleted cancer cells.

Mina53 catalyzes arginine demethylation of p53 to promote tumor growth

Arginine methylation is a common post-translational modification that plays critical roles in many biological processes. However, the existence of arginine demethylases that remove the modification has not been fully established. Here, we report that Myc-induced nuclear antigen 53 (Mina53), a member of the jumonji C (JmjC) protein family, is an arginine demethylase. Mina53 catalyzes the removal of asymmetric dimethylation at arginine 337 of p53. Mina53-mediated demethylation reduces p53 stability and oligomerization and alters chromatin modifications at the gene promoter, thereby suppressing p53-mediated transcriptional activation and cell-cycle arrest. Mina53 represses p53-dependent tumor suppression both in mouse xenografts and spontaneous tumor models. Moreover, downregulation of p53-mediated gene expression is observed in several types of cancer with elevated expression of Mina53. Thus, our study reveals a regulatory mechanism of p53 homeostasis and activity and, more broadly, defines a paradigm for dynamic arginine methylation in controlling important biological functions.

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

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

TNG908 is a brain-penetrant, MTA-cooperative PRMT5 inhibitor developed for the treatment of MTAP-deleted cancers

TNG908 is a clinical stage PRMT5 inhibitor with an MTA-cooperative binding mechanism designed to leverage the synthetic lethal interaction between PRMT5 inhibition and MTAP deletion. MTAP deletion occurs in 10-15 % of all human cancer representing multiple histologies. MTA is a negative regulator of PRMT5 that accumulates as a result of MTAP deletion. In this study, we demonstrate that TNG908 selectively binds the PRMT5·MTA complex driving selective inhibition of PRMT5 in MTAP-null cancers, a mechanism that creates a large therapeutic index relative to first generation PRMT5 inhibitors that have alternative binding mechanisms that are not tumor-selective. Strong preclinical activity in multiple MTAP-deleted xenograft models, as well as demonstrated brain penetrance in preclinical models, support the potential for histology-agnostic clinical development of TNG908 in MTAP-deleted solid tumors, including CNS malignancies. TNG908 is being tested clinically in patients with MTAP-deleted tumors, including glioblastoma, in a Phase I/II clinical trial (NCT05275478).

Substrate adaptors are flexible tethering modules that enhance substrate methylation by the arginine methyltransferase PRMT5

Protein arginine methyltransferase (PRMT) 5 is an essential arginine methyltransferase responsible for the majority of cellular symmetric dimethyl-arginine marks. PRMT5 uses substrate adaptors such as pICln, RIOK1, and COPR5 to recruit and methylate a wide range of substrates. Although the substrate adaptors play important roles in substrate recognition, how they direct PRMT5 activity towards specific substrates remains incompletely understood. Using biochemistry and cryogenic electron microscopy, we show that these adaptors compete for the same binding site on PRMT5. We find that substrate adaptor and substrate complexes are bound to PRMT5 through two peptide motifs, enabling these adaptors to act as flexible tethering modules to enhance substrate methylation. Taken together, our results shed structural and mechanistic light on the PRMT5 substrate adaptor function and the biochemical nature of PRMT5 interactors.

PRMT1 Promotes the Self-renewal of Leukemia Stem Cells by Regulating Protein Synthesis

The application of tyrosine kinase inhibitors (TKIs) has revolutionized the management of chronic myeloid leukemia (CML). However, disease relapse and progression particularly due to persistent leukemia stem cells (LSCs) remain a big challenge in the clinic. Therefore, validation of the therapeutic vulnerability in LSCs is urgently needed. This study verifies the critical role of protein arginine methyltransferase 1 (PRMT1) in the maintenance of CML LSCs. It is found that PRMT1 promotes the survival and serially plating abilities of human primary CML LSCs. Genetic deletion of Prmt1 significantly delays the leukemogenesis and impairs the self-renewal of LSCs in BCR-ABL-driven CML mice. PRMT1 regulates LSCs and leukemia development depending on its methyltransferase activity. Pharmacological inhibition of PRMT1 activity by MS023 remarkably eliminates LSCs and prolongs the survival of CML mice. Mechanistical studies reveal that PRMT1 promotes transcriptional activation of ribosomal protein L29 (RPL29) via catalyzing asymmetric dimethylation of histone H4R3 (H4R3me2a) at its gene promoter region. PRMT1 augments the global protein synthesis via RPL29 in CML LSCs. Taken together, the findings provide new evidence that histone arginine methylation modification regulates protein synthesis in LSCs and highlight PRMT1 as a valuable druggable target for patients with CML.

PRMT3 and CARM1: Emerging Epigenetic Targets in Cancer

The family of protein arginine methyltransferases (PRMTs) occupies an important position in biology, especially during the initiation and development of cancer. PRMT3 and CARM1(also known as PRMT4), being type I protein arginine methyltransferases, are key in controlling tumour progression by catalysing the mono-methylation and asymmetric di-methylation of both histone and non-histone substrates. This paper reviews the functions and potential therapeutic target value of PRMT3 and CARM1 in a variety of cancers. Studies have identified abnormal expressions of PRMT3 and CARM1 in several malignancies, closely linked to cancer progression, advancement, and resistance to treatment. Such as hepatocellular carcinoma, colorectal cancer, ovarian cancer, and endometrial cancer. These findings offer new strategies and directions for cancer treatment, especially in enhancing the effectiveness of conventional treatment methods.

Therapeutic Potential of PRMT1 as a Critical Survival Dependency Target in Multiple Myeloma

Multiple myeloma (MM) is a neoplasm of antibody-producing plasma cells and is the second most prevalent hematological malignancy worldwide. Development of drug resistance and disease relapse significantly impede the success of MM treatment, highlighting the critical need to discover novel therapeutic targets. In a custom CRISPR/Cas9 screen targeting 197 DNA damage response-related genes, Protein Arginine N-Methyltransferase 1 (PRMT1) emerged as a top hit, revealing it as a potential therapeutic vulnerability and survival dependency in MM cells. PRMT1, a major Type I PRMT enzyme, catalyzes the asymmetric transfer of methyl groups to arginine residues, influencing gene transcription and protein function through post-translational modification. Dysregulation or overexpression of PRMT1 has been observed in various malignancies including MM and is linked to chemoresistance. Treatment with the Type I PRMT inhibitor GSK3368715 resulted in a dose-dependent reduction in cell survival across a panel of MM cell lines. This was accompanied by reduced levels of asymmetric dimethylation of arginine (ADMA) and increased arginine monomethylation (MMA) in MM cells. Cell cycle analysis revealed an accumulation of cells in the G0/G1 phase and a reduction in the S phase upon GSK3368715 treatment. Additionally, PRMT1 inhibition led to a significant downregulation of genes involved in cell proliferation, DNA replication, and DNA damage response (DDR), likely inducing genomic instability and impairing tumor growth. This was supported by Reverse Phase Protein Array (RPPA) analyses, which revealed a significant reduction in levels of proteins associated with cell cycle regulation and DDR pathways. Overall, our findings indicate that MM cells critically depend on PRMT1 for survival, highlighting the therapeutic potential of PRMT1 inhibition in treating MM.

Discovery of Potent, Highly Selective, and Orally Bioavailable MTA Cooperative PRMT5 Inhibitors with Robust In Vivo Antitumor Activity

Protein arginine methyltransferase 5 (PRMT5), which catalyzes the symmetric dimethylation of arginine residues on target proteins, plays a critical role in gene expression regulation, RNA processing, and signal transduction. Aberrant PRMT5 activity has been implicated in cancers and other diseases, making it a potential therapeutic target. Here, we report the discovery of a methylthioadenosine (MTA) cooperative PRMT5 inhibitor. Compound 20 exhibited strong antiproliferation activity in multiple MTAP-deleted cancer cell lines, excellent selectivity over MTAP wild-type cell lines, as well as satisfactory oral pharmacokinetic properties over various preclinical species. Notably, compound 20 demonstrated a dose-dependent reduction of symmetric dimethylarginine (SDMA) expression in the LU99 cell line and robust in vivo antitumor activity in the LU99 subcutaneous model.

DRBD18 acts as a transcript-specific RNA editing auxiliary factor in Trypanosoma brucei

Uridine insertion/deletion (U-indel) RNA editing of mitochondrial transcripts is a posttranscriptional modification in kinetoplastid organisms, resulting in the generation of mature mRNAs from cryptic precursors. This RNA editing process involves a multiprotein complex holoenzyme and multiple accessory factors. Recent investigations have highlighted the pivotal involvement of accessory RNA-binding proteins (RBPs) in modulating RNA editing in Trypanosoma brucei, often in a transcript-specific manner. DRBD18 is a multifunctional RBP that reportedly impacts the stability, processing, export, and translation of nuclear-encoded mRNAs. However, mass spectrometry studies report DRBD18-RESC interactions, prompting us to investigate its role in mitochondrial U-indel RNA editing. In this study, we demonstrate the specific and RNase-sensitive interaction of DRBD18 with multiple RESC factors. Depletion of DRBD18 through RNA interference in procyclic form T. brucei leads to a significant reduction in the levels of edited A6 and COIII mitochondrial transcripts, whereas its overexpression causes a notable increase in the abundance of these edited mRNAs. RNA immunoprecipitation/qRT-PCR analysis indicates a direct role for DRBD18 in A6 and COIII mRNA editing. We also examined the impact of arginine methylation of DRBD18 in the editing process, revealing that the hypomethylated form of DRBD18, rather than the arginine-methylated version, is essential for promoting these editing events. In conclusion, our findings demonstrate that DRBD18 directly affects the editing of A6 and COIII mRNAs, with its function being modulated by its arginine methylation status, marking the first report of a mitochondrial function for this protein and identifying it as a newly characterized RNA editing auxiliary factor.

PRMT5 inhibition has a potent anti-tumor activity against adenoid cystic carcinoma of salivary glands

BACKGROUND

Adenoid cystic carcinoma (ACC) is a rare glandular malignancy, commonly originating in salivary glands of the head and neck. Given its protracted growth, ACC is usually diagnosed in advanced stage. Treatment of ACC is limited to surgery and/or adjuvant radiotherapy, which often fails to prevent disease recurrence, and no FDA-approved targeted therapies are currently available. As such, identification of new therapeutic targets specific to ACC is crucial for improved patients' outcomes.

METHODS

After thoroughly evaluating the gene expression and signaling patterns characterizing ACC, we applied PandaOmics (an AI-driven software platform for novel therapeutic target discovery) on the unique transcriptomic dataset of 87 primary ACCs. Identifying protein arginine methyl transferase 5 (PRMT5) as a putative candidate with the top-scored druggability, we next determined the applicability of PRMT5 inhibitors (PRT543 and PRT811) using ACC cell lines, organoids, and patient derived xenograft (PDX) models. Molecular changes associated with response to PRMT5 inhibition and anti-proliferative effect of the combination therapy with lenvatinib was then analyzed.

RESULTS

Using a comprehensive AI-powered engine for target identification, PRMT5 was predicted among potential therapeutic target candidates for ACC. Here we show that monotherapy with selective PRMT5 inhibitors induced a potent anti-tumor activity across several cellular and animal models of ACC, which was paralleled by downregulation of genes associated with ACC tumorigenesis, including MYB and MYC (the recognized drivers of ACC progression). Furthermore, as a subset of genes targeted by lenvatinib is upregulated in ACC, we demonstrate that addition of lenvatinib enhanced the growth inhibitory effect of PRMT5 blockade in vitro, suggesting a potential clinical benefit for patients expressing lenvatinib favorable molecular profile.

CONCLUSION

Taken together, our study underscores the role of PRMT5 in ACC oncogenesis and provides a strong rationale for the clinical development of PRMT5 inhibitors as a targeted monotherapy or combination therapy for treatment of patients with this rare disease, based on the analysis of their underlying molecular profile.

Design, Synthesis, and Biological Evaluation of 3,4-Dihydroisoquinolin-1(2H)-one Derivatives as Protein Arginine Methyltransferase 5 Inhibitors for the Treatment of Non-Hodgkin's Lymphoma

Through catalyzing the transfer of methyl groups onto the guanidinium of arginine, protein arginine methyltransferase 5 (PRMT5) was essential to the cell growth of cancer cells. By utilizing a scaffold hopping strategy, a novel series of 3,4-dihydroisoquinolin-1(2H)-one derivatives were designed and synthesized. Through a systematic SAR study, D3 demonstrated excellent PRMT5 inhibitory activity, potent antiproliferative activity against Z-138, favorable pharmacokinetic profiles, and low hERG toxicity. Molecular docking, molecular dynamic (MD) simulation, and surface plasmon resonance (SPR) study indicated that D3 was tightly interacted with PRMT5. Meanwhile, D3 exhibited high selectivity against PRMT5, which could inhibit the growth of various cancer cells, induce apoptosis, and arrest the cell cycle in the G0/G1 phase. Additionally, D3 possessed excellent antitumor efficacy in Z-138 xenograft models, low toxicity in vivo, and acceptable drug metabolism and pharmacokinetics (DMPK) profiles in vitro. Therefore, D3 can be developed as a promising candidate for the treatment of non-Hodgkin's lymphoma (NHL).

One stone two birds: Introducing piperazine into a series of nucleoside derivatives as potent and selective PRMT5 inhibitors

The protein arginine methyltransferase 5 (PRMT5) has emerged as potential target for the treatment of cancer. Many efforts have been made to develop potent and selective PRMT5 inhibitors targeting either S-adenosyl methionine (SAM) pocket or substrate binding pocket. Here, we rationally designed a series of nucleoside derivatives incorporated with piperazine as novel PRMT5 inhibitors occupying both pockets. The representative compound 36 exhibited highly potent PRMT5 inhibition activity as well as good selectivity over other methyltransferases. Further cellular experiments revealed that compound 36 potently reduced the level of symmetric dimethylarginines (sDMA) and inhibited the proliferation of MOLM-13 cell lines by inducing apoptosis and cell cycle arrest. Moreover, compound 36 had more favorable metabolic stability and aqueous solubility than JNJ64619178 (9). Meanwhile, it obviously suppressed the tumor growth in a MOLM-13 tumor xenograft model. These results clearly indicate that 36 is a highly potent and selective PRMT5 inhibitor worthy for further development.

PRMT1-Mediated Arginine Methylation Promotes Corneal Epithelial Wound Healing via Epigenetic Regulation of ANXA3

Purpose

Protein arginine methyltransferase 1 (PRMT1) is an integral constituent of numerous cellular processes. However, its role in corneal epithelial wound healing (CEWH) remains unclear. This study investigates the impact of PRMT1 on cellular mechanisms underlying corneal epithelial repair and its potential to improve wound healing outcomes.

Methods

The murine CEWH model was established using an Alger brush. Corneal epithelial-specific Prmt1 knockout mice were generated using the Cre-lox system. Quantitative reverse transcription polymerase chain reaction and Western blot analyses determined the expression of candidate genes at mRNA and protein expression levels. Human corneal epithelial cells (HCECs) were transfected with siRNA using Lipofectamine RNAiMAX or infected with lentivirus to precisely alter the expression of PRMT1 or Annexin A3 (ANXA3). EdU and a scratch wound-healing assay evaluated the effects of PRMT1 or ANXA3 on HCEC proliferation and migration, respectively. Rescue experiment and chromatin immunoprecipitation assay validate the correlation between PRMT1 and ANXA3.

Results

Prmt1 is significantly upregulated during CEWH, accompanied by an elevated global arginine methylation level. Knockdown of PRMT1 in HCECs or in vivo knockout impairs cell proliferation, migration, and the CEWH process. Furthermore, ANXA3 was identified as a critical target of PRMT1, with PRMT1 enhancing ANXA3 expression through histone arginine methylation at its promoter region, establishing a causal correlation between them. Moreover, PRMT1 can modulate the NF-κB and JNK signaling pathways via ANXA3.

Conclusions

PRMT1 is a critical epigenetic regulator in CEWH, promoting wound healing by upregulating ANXA3 via histone arginine methylation. These findings highlight the potential of targeting PRMT1 to enhance corneal epithelial repair.

Phosphoinositide signaling in the nucleus: Impacts on chromatin and transcription regulation

Phosphoinositides also called Polyphosphoinositides (PPIns) are small lipid messengers with established key roles in organelle trafficking and cell signaling in response to physiological and environmental inputs. Besides their well-described functions in the cytoplasm, accumulating evidences pointed to PPIns involvement in transcription and chromatin regulation. Through the description of previous and recent advances of PPIns implication in transcription, this review highlights key discoveries on how PPIns modulate nuclear factors activity and might impact chromatin to modify gene expression. Finally, we discuss how PPIns nuclear and cytosolic metabolisms work jointly in orchestrating key transduction cascades that end in the nucleus to modulate gene expression.

ZBED3 exacerbates hyperglycemia by promoting hepatic gluconeogenesis through CREB signaling

BACKGROUND

Elevated hepatic glucose production (HGP) is a prominent manifestation of impaired hepatic glucose metabolism in individuals with diabetes. Increased hepatic gluconeogenesis plays a pivotal role in the dysregulation of hepatic glucose metabolism and contributes significantly to fasting hyperglycemia in diabetes. Previous studies have identified zinc-finger BED domain-containing 3 (ZBED3) as a risk gene for type 2 diabetes (T2DM), and its single nucleotide polymorphism (SNPs) is closely associated with the fasting blood glucose level, suggesting a potential correlation between ZBED3 and the onset of diabetes. This study primarily explores the effect of ZBED3 on hepatic gluconeogenesis and analyzes the relevant signaling pathways that regulate hepatic gluconeogenesis.

METHODS

The expression level of ZBED3 was assessed in the liver of insulin-resistant (IR)-related disease. RNA-seq and bioinformatics analyses were employed to examine the ZBED3-related pathway that modulated HGP. To investigate the role of ZBED3 in hepatic gluconeogenesis, the expression of ZBED3 was manipulated by upregulation or silencing using adeno-associated virus (AAV) in mouse primary hepatocytes (MPHs) and HHL-5 cells. In vivo, hepatocyte-specific ZBED3 knockout mice were generated. Moreover, AAV8 was employed to achieve hepatocyte-specific overexpression and knockdown of ZBED3 in C57BL/6 and db/db mice. Immunoprecipitation and mass spectrometry (IP-MS) analyses were employed to identify proteins that interacted with ZBED3. Co-immunoprecipitation (co-IP), glutathione S-transferase (GST) - pulldown, and dual-luciferase reporter assays were conducted to further elucidate the underlying mechanism of ZBED3 in regulating hepatic gluconeogenesis.

RESULTS

The expression of ZBED3 in the liver of IR-related disease models was found to be increased. Under the stimulation of glucagon, ZBED3 promoted the expression of hepatic gluconeogenesis-related genes PGC1A, PCK1, G6PC, thereby increasing HGP. Consistently, the rate of hepatic gluconeogenesis was found to be elevated in mice with hepatocyte-specific overexpression of ZBED3 and decreased in those with ZBED3 knockout. Additionally, the knockdown of ZBED3 in the liver of db/db mice resulted in a reduction in hepatic gluconeogenesis. Moreover, the study revealed that ZBED3 facilitated the nuclear translocation of protein arginine methyltransferases 5 (PRMT5) to influence the regulation of PRMT5-mediated symmetrical dimethylation of arginine (s-DMA) of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB), which in turn affects the phosphorylation of CREB and ultimately promotes HGP.

CONCLUSIONS

This study indicates that ZBED3 promotes hepatic gluconeogenesis and serves as a critical regulator of the progression of diabetes.

A new pathway for ferroptosis regulation: The PRMTs

Protein arginine methyltransferases (PRMTs) play an essential role in the regulation of ferroptosis, a form of programmed cell death characterized by abnormal iron ion metabolism, lipid peroxidation, and DNA damage. Through methylation, PRMTs modify specific proteins, thereby altering their activity, localizations, or interactions with other molecules to control the ferroptosis process. This study was conducted to provide a comprehensive overview of the relationship between PRMTs and ferroptosis, with a focus on the mechanisms by which PRMTs regulate ferroptosis and their effect on this cell death pathway. Currently, only a few studies have been conducted on the regulation of ferroptosis by PRMTs. However, this review provides insights into the effects of PRMTs on ferroptosis regulators, suggesting that the regulation of ferroptosis by PRMTs holds potential as a new therapeutic target for related diseases.

Targeting PRMT1 Reduces Cancer Persistence and Tumor Relapse in EGFR- and KRAS-Mutant Lung Cancer

SIGNIFICANCE

Eliminating "persisters" before relapse is crucial for achieving durable treatment efficacy. This study provides a rationale for developing PRMT1-selective inhibitors to target cancer persisters and achieve more durable outcomes in oncogene-targeting therapies.

Protein arginine methyltransferase 7 modulators in disease therapy: Current progress and emerged opportunity

Protein arginine methyltransferase 7 (PRMT7) is an essential epigenetic and post-translational regulator in eukaryotic organisms. Dysregulation of PRMT7 is intimately related to multiple types of human diseases, particularly cancer. In addition, PRMT7 exerts multiple effects on cellular processes such as growth, migration, invasion, apoptosis, and drug resistance in various cancers, making it as a promising target for anti-tumor therapeutics. In this review, we initially provide an overview of the structure and biological functions of PRMT7, along with its association with diseases. Subsequently, we summarized the PRMT inhibitors in clinical trials and the co-crystal structural of PRMT7 inhibitors. Moreover, we also focus on recent progress in the design and development of modulators targeting PRMT7, including isoform-selective and non-selective PRMT7 inhibitors, and the dual-target inhibitors based on PRMT7, from the perspectives of rational design, pharmacodynamics, pharmacokinetics, and the clinical status of these modulators. Finally, we also provided the challenges and prospective directions for PRMT7 targeting drug discovery in cancer therapy.

Loss of MTAP expression is strongly linked to homozygous 9p21 deletion, unfavorable tumor phenotype, and noninflamed microenvironment in urothelial bladder cancer

Homozygous 9p21 deletions usually result in a complete loss of S-methyl-5'-thioadenosine phosphorylase (MTAP) expression visualizable by immunohistochemistry (IHC). MTAP deficiency has been proposed as a marker for predicting targeted treatment response. A tissue microarray including 2,710 urothelial bladder carcinomas were analyzed for 9p21 deletion by fluorescence in situ hybridization and MTAP expression by IHC. Data were compared with data on tumor phenotype, patient survival, intratumoral lymphocyte subsets, and PD-L1 expression. The 9p21 deletion rate increased from pTaG2 low (9.2% homozygous, 25.8% heterozygous) to pTaG2 high (32.6%, 20.9%; p < 0.0001) but was slightly lower in pTaG3 (16.7%, 16.7%) tumors. In pT2-4 carcinomas, 23.3% homozygous and 17.9% heterozygous deletions were found, and deletions were tied to advanced pT (p = 0.0014) and poor overall survival (p = 0.0461). Complete MTAP loss was seen in 98.4% of homozygous deleted while only 1.6% of MTAP negative tumors had retained 9p21 copies (p < 0.0001). MTAP loss was linked to advanced stage and poor overall survival in pT2-4 carcinomas (p < 0.05 each). The relationship between 9p21 deletions/MTAP loss and poor patient prognosis was independent of pT and pN (p < 0.05 each). The 9p21 deletions were associated with a noninflamed microenvironment (p < 0.05). Complete MTAP loss is strongly tied to homozygous 9p21 deletion, aggressive disease, and noninflamed microenvironment. Drugs targeting MTAP-deficiency may be useful in urothelial bladder carcinoma. MTAP IHC is a near perfect surrogate for MTAP deficiency in this tumor type.

The HIV-1 Transcriptional Program: From Initiation to Elongation Control

A large body of work in the last four decades has revealed the key pillars of HIV-1 transcription control at the initiation and elongation steps. Here, I provide a recount of this collective knowledge starting with the genomic elements (DNA and nascent TAR RNA stem-loop) and transcription factors (cellular and the viral transactivator Tat), and later transitioning to the assembly and regulation of transcription initiation and elongation complexes, and the role of chromatin structure. Compelling evidence support a core HIV-1 transcriptional program regulated by the sequential and concerted action of cellular transcription factors and Tat to promote initiation and sustain elongation, highlighting the efficiency of a small virus to take over its host to produce the high levels of transcription required for viral replication. I summarize new advances including the use of CRISPR-Cas9, genetic tools for acute factor depletion, and imaging to study transcriptional dynamics, bursting and the progression through the multiple phases of the transcriptional cycle. Finally, I describe current challenges to future major advances and discuss areas that deserve more attention to both bolster our basic knowledge of the core HIV-1 transcriptional program and open up new therapeutic opportunities.

Basic Epigenetic Mechanisms

The human genome consists of 23 chromosome pairs (22 autosomes and one pair of sex chromosomes), with 46 chromosomes in a normal cell. In the interphase nucleus, the 2 m long nuclear DNA is assembled with proteins forming chromatin. The typical mammalian cell nucleus has a diameter between 5 and 15 μm in which the DNA is packaged into an assortment of chromatin assemblies. The human brain has over 3000 cell types, including neurons, glial cells, oligodendrocytes, microglial, and many others. Epigenetic processes are involved in directing the organization and function of the genome of each one of the 3000 brain cell types. We refer to epigenetics as the study of changes in gene function that do not involve changes in DNA sequence. These epigenetic processes include histone modifications, DNA modifications, nuclear RNA, and transcription factors. In the interphase nucleus, the nuclear DNA is organized into different structures that are permissive or a hindrance to gene expression. In this chapter, we will review the epigenetic mechanisms that give rise to cell type-specific gene expression patterns.

PRMT5 Inhibitor EPZ015666 Decreases the Viability and Encystment of Entamoeba invadens

Protein arginine methyltransferase 5 (PRMT5) is an enzyme that produces monomethyl arginine (MMA) and symmetric dimethyl arginine (sDMA), post-translational modifications that regulate several cellular processes, including stage conversion in parasitic protozoans. Entamoeba histolytica, the etiologic agent of human amebiasis, has two stages in its life cycle, the trophozoite, which is the replicative form, and the cyst, corresponding to the infective phase. The study of the molecular mechanisms that regulate differentiation in this parasite has been overdue because of a lack of efficient protocols for in vitro encystment. For this reason, Entamoeba invadens, a parasite of reptiles, has been used as a differentiation model system for the genus. Here, we demonstrated the presence of sDMA in E. invadens, which increases during encystment, and identified the PRMT5 of this microorganism (EiPRMT5). In addition, we performed 3D modeling of this enzyme, as well as its molecular docking with the PRMT5 inhibitor EPZ015666, which predicted the affinity of the drug for the active site of the enzyme. In agreement with these findings, EPZ015666 reduced trophozoite viability and encystment. Therefore, EiPRMT5 is a potential target for inhibiting the spread of amebiasis.

New advances in the role of JAK2 V617F mutation in myeloproliferative neoplasms

The JAK2 V617F mutation is the most common driver gene in myeloproliferative neoplasm (MPN), which means that the JAK/STAT signaling pathway is persistently activated independent of cytokines, and plays an important part in the onset and development of MPN. The JAK inhibitors, although widely used in the clinical practice, are unable to eradicate MPN. Therefore, the unavoidable long-term treatment poses a serious burden for patients with MPN. It is established that the JAK2 V617F mutation, in addition its role in the JAK/STAT pathway, can promote cell proliferation, differentiation, anti-apoptosis, DNA damage accumulation, and other key biologic processes through multiple pathways. Other than that, the JAK2 V617F mutation affects the cardiovascular system through multiple mechanisms. Although JAK inhibitors cannot eradicate MPN cells, the combined use of JAK inhibitors and other drugs may have surprising effects. This requires an in-depth understanding of the mechanism of action of the JAK2 V617F mutation. In this review, the authors explored the role of the JAK2 V617F mutation in MPN from multiple aspects, including the mechanisms of non-JAK/STAT pathways, the regulation of cellular methylation, the induction of cellular DNA damage accumulation, and effects on the cardiovascular system, with the objective of providing valuable insights into multidrug combination therapy for MPN.

PRMT1 alleviates isoprenaline-induced myocardial hypertrophy by methylating SRSF1

Myocardial hypertrophy (MH) is an important factor contributing to severe cardiovascular disease. Previous studies have demonstrated that specific deletion of the protein arginine methyltransferase 1 (PRMT1) leads to MH, but the exact mechanism remains unclear. Serine/arginine-rich splicing factor 1 (SRSF1) affects the development and progression of cardiovascular disease by selectively splicing downstream signaling proteins. The present study is designed to determine whether PRMT1 is involved in MH by regulating SRSF1 and, if so, to explore the underlying mechanisms. Adult male mice and H9C2 cardiomyocytes are treated with isoprenaline (ISO) to establish MH models. The expression levels of PRMT1 are significantly decreased in the ISO-induced MH models, and inhibiting PRMT1 worsens MH, whereas overexpression of PRMT1 ameliorates MH. SRSF1 serves as the downstream target of PRMT1, and its expression is markedly elevated in MH. Moreover, SRSF1 increases the mRNA expressions of CaMKIIδ A and CaMKIIδ B, decreases the mRNA expression of CaMKIIδ C by altering the selective splicing of CaMKIIδ, and further participates in MH. In addition, there is an interaction between PRMT1 and SRSF1, whereby PRMT1 reduces the phosphorylation level of SRSF1 via methylation, thus further altering its functional activity and eventually improving MH. Our present study demonstrates that PRMT1 relieves MH by methylating SRSF1, which is expected to provide a new theoretical basis for the pathogenic mechanism of MH and potential drug targets for reducing MH and associated cardiovascular disease.

A review of the known MTA-cooperative PRMT5 inhibitors

Protein arginine methyltransferase 5 (PRMT5), an epigenetic target with significant clinical potential, is closely associated with the occurrence and development of a range of tumours and has attracted considerable interest from the pharmaceutical industry and academic research communities. According to incomplete statistics, more than 10 PRMT5 inhibitors for cancer therapy have entered clinical trials in recent years. Among them, the second-generation PRMT5 inhibitors developed based on the synthetic lethal strategy demonstrate considerable clinical application value. This suggests that, following the precedent of poly ADP ribose polymerase (PARP), PRMT5 has the potential to become the next clinically applicable synthetic lethal target. However, due to the inherent dose-limiting toxicity of epigenetic target inhibitors, none of these PRMT5 inhibitors has been approved for marketing to date. In light of this, we have conducted a review of the design thoughts and the structure-activity relationship (SAR) of known methylthioadenosine (MTA)-cooperative PRMT5 inhibitors. Additionally, we have analysed the clinical safety of representative first- and second-generation PRMT5 inhibitors. This paper discusses the in vivo vulnerability of the aromatic amine moiety of the second-generation PRMT5 inhibitor based on its structure. It also considers the potential nitrosamine risk factors associated with the preparation process.