Asymmetrical methyltransferase PRMT3 regulates human mesenchymal stem cell osteogenesis via miR-3648

Inflammation in cancer cachexia: still the central tenet or just another player?

Cancer cachexia, a multifactorial syndrome characterized by body weight loss, muscle, and adipose tissue wasting, affects patients with cancer. Over time, the definition of cachexia has been modified, including inflammation as one of the main causal factors. Evidence has suggested that a range of proinflammatory mediators may be involved in the regulation of intracellular signaling, resulting in enhanced resting energy expenditure, metabolic changes, and muscle atrophy, all of which are typical features of cachexia. Physiologically speaking, however, inflammation is a response aimed at facing potentially damaging events. Along this line, its induction in the cancer hosts could be an attempt to restore the physiological homeostasis. Interesting observations have shown that cytokines such as interleukins 4 and 6 could improve muscle wasting, supporting the view that the same mediator may exert pro- or anti-inflammatory activity depending on the immune cells involved as well as on the tissue metabolic demand. In conclusion, whether inflammation is crucial to the occurrence of cachexia or just one contributor among others, is still unclear. Indeed, while inflammation is a trigger of cachexia, the alterations of energy and protein metabolism and of the hormonal homeostasis occurring in cachexia likely act as inflammatory stimuli on their own. Whether the causative role prevails over the compensatory one likely depends on the tumor type and stage, patient lifestyle, the presence of comorbidities, and the response to anticancer treatments paving the way to a holistic, personalized approach to cancer cachexia.

PRMT3 reverses HIV-1 latency by increasing chromatin accessibility to form a TEAD4-P-TEFb-containing transcriptional hub

Latent HIV-1 presents a formidable challenge for viral eradication. HIV-1 transcription and latency reversal require interactions between the viral promoter and host proteins. Here, we perform the dCas9-targeted locus-specific protein analysis and discover the interaction of human arginine methyltransferase 3 (PRMT3) with the HIV-1 promoter. This interaction reverses latency in cell line models and primary cells from latently infected persons by increasing the levels of H4R3Me2a and transcription factor P-TEFb at the viral promoter. PRMT3 is found to promote chromatin accessibility and transcription of HIV-1 and a small subset of host genes in regions harboring the classical recognition motif for another transcription factor TEAD4. This motif attracts TEAD4 and PRMT3 to the viral promoter to synergistically activate transcription. Physical interactions among PRMT3, P-TEFb, and TEAD4 exist, which may help form a transcriptional hub at the viral promoter. Our study reveals the potential of targeting these hub proteins to eradicate latent HIV-1.

PRMT3-Mediated H4R3me2a Promotes Primary Age-Related Tauopathy by Driving Tau Hyperphosphorylation in Neuron

Primary age-related tauopathy (PART) and Alzheimer's disease (AD) both exhibit 3R/4R hyperphosphorylated tau-positive neurofibrillary tangles (NFTs) within the hippocampal-entorhinal system. Notably, PART patients show a higher degree of tau hyperphosphorylation in the entorhinal cortex (EC) than AD, yet the molecular mechanisms driving Aβ-independent tau hyperphosphorylation in PART remain poorly understood. Herein, through transcriptomic profiling of postmortem EC tissues and in vitro and in vivo functional validation, the present study identifies protein arginine methyltransferase 3 (PRMT3) as a critical driver of tau hyperphosphorylation. Mechanistically, PRMT3-mediated tau hyperphosphorylation is dependent on asymmetric dimethylation of histone H4 at arginine 3 (H4R3me2a), which upregulates miR-448. Elevated miR-448 specifically targets and suppresses IGF1R, leading to downstream GSK3β activation and subsequent tau hyperphosphorylation through PI3K/AKT/GSK3β signaling. Treatment with SGC707, a selective PRMT3 inhibitor, effectively reduces tau hyperphosphorylation and demonstrates therapeutic promise for PART and potentially other tauopathies. Collectively, this study defines the PRMT3/H4R3me2a/miR-448 axis as a critical regulatory pathway in tau hyperphosphorylation within PART, underscoring the potential of PRMT3 inhibition as a targeted therapeutic strategy for tauopathies.

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.

PRMT3 gene expression and methylation levels in arrested embryos: Implications for developmental arrest defects

Embryos generated through in vitro fertilization (IVF) frequently experience developmental arrests or blocks, which significantly reduces the success rate of IVF therapy. Recent studies have shown that the protein arginine methylase 3 (PRMT3) plays a crucial role in the regulating of gene expression during early embryonic development. However, the exact regulatory mechanisms of PRMT3 involved in early embryonic development are still unclear. In this study, we used discarded arrested and polyspermic embryos from IVF for experiments, employing confocal techniques and qRT-PCR to examine PRMT3 expression and changes in H4R3me2a methylation during various stages of early development. Furthermore, PRMT3 was re-expressed in the arrested embryos to observe their subsequent development. Our findings revealed that PRMT3 nucleic acid and protein were significantly lower in arrested embryos than in control embryos (P < 0.05). Additionally, methylation levels of H4R3me2a were significantly lower in arrested embryos (P < 0.05). Re-expression of PRMT3 could partially rescue embryos that are developmentally arrested, and even a few arrested embryos have the potential to develop into morula or blastocysts. In summary, the reduction or deletion of PRMT3 gene in early embryo may lead to developmental arrested defects. Therefore, it is crucial to regulate the expression and functioning of PRMT3 for the proper development of early embryos, and further research is required to investigate potential therapeutic interventions for embryonic development arrest in vitro.

PRMT7-Mediated PTEN Activation Enhances Bone Regeneration in Female Mice

Epigenetic regulation provides new insights into the mechanisms of osteogenic differentiation and identifies potential targets for treating bone-related diseases. However, the specific regulatory networks and mechanisms involved still need further investigation. In this study, we identify PRMT7 as a novel epigenetic regulator of mesenchymal stem cells (MSCs) osteogenic commitment. Conditional knockout of Prmt7 in mice reveals a significant impairment in osteogenesis and bone regeneration, specifically in females, affecting both femurs and mandibles, with no noticeable effect in males. Mechanistically, PRMT7 modulates MSCs osteogenic differentiation by activating PTEN. Specifically, PRMT7 enhances PTEN transcription by increasing H3R2me1 levels at the PTEN promoter. Additionally, PRMT7 interacts with the PTEN protein and stabilizes nuclear PTEN, revealing an unprecedented pathway. Notably, overexpression of PTEN alleviates the osteogenic deficits observed in Prmt7-deficient mice. This research establishes PRMT7 as a potential therapeutic target for promoting bone formation/regeneration and offers novel molecular insights into the PRMT7-PTEN regulatory axis, underscoring its significance in bone biology and regenerative medicine.

PRMT3 drives PD-L1-mediated immune escape through activating PDHK1-regulated glycolysis in hepatocellular carcinoma

Aberrant expression of programmed death ligand-1 (PD-L1) facilitates tumor immune evasion. Protein arginine methyltransferase 3 (PRMT3), a member of type I PRMT family, mediates asymmetric dimethylarginine (ADMA) modification of various substrate proteins. This study investigates the role of PRMT3 in PD-L1-associated tumor immunosuppression in hepatocellular carcinoma (HCC). Hepatocyte-specific knockout of Prmt3 significantly suppressed HCC progression in DEN-CCL4-treated mice. Knockout of Prmt3 in HCC cells markedly increased CD8+ T cell infiltration, and reduced lactate production in tumors. PRMT3 interacted with pyruvate dehydrogenase kinase 1 (PDHK1), asymmetric dimethylation of PDHK1 at arginine 363 and 368 residues and increased its kinase activity. The R363/368 K mutant or inhibition of PDHK1 by JX06 blocked the effect of PRMT3 on lactate production. JX06 treatment also attenuated the tumor-promoting role of PRMT3 in HCC in vitro and in vivo. Furthermore, RNA-seq analysis revealed that knockout of PRMT3 downregulates the tumor-associated immune checkpoint, PD-L1, in tumor tissues. Chromatin immunoprecipitation (ChIP) assay demonstrated that PRMT3 promotes lactate-induced PD-L1 expression by enhancing the direct binding of histone H3 lysine 18 lactylation (H3K18la) to the PD-L1 promoter. Tissue microarray analysis showed a positive correlation between PRMT3 and PD-L1 expression in HCC patients. Anti-PD-L1 treatment reversed PRMT3-induced tumor growth and restored CD8+ T cell infiltration. Our research links PRMT3-mediated metabolic reprogramming and immune evasion, revealing that the PRMT3-PDHK1-lactate-PD-L1 axis may be a potential target for improving the efficacy of immunotherapy in HCC.

Biomedical effects of protein arginine methyltransferase inhibitors

Protein arginine methyltransferases (PRMTs) are enzymes that catalyze the methylation of arginine residues in eukaryotic proteins, playing critical roles in modulating diverse cellular processes. The importance of PRMTs in the incidence and progression of a wide range of diseases, particularly cancers, such as breast, liver, lung, colorectal cancer, lymphoma, leukemia, and acute myeloid leukemia is increasingly recognized. This underscores the critical need for the development of effective PRMT inhibitors as therapeutic intervention. The field of PRMT inhibitors is in the rapidly growing phase and it is necessary to conduct a summative review of how the so-far developed inhibitors impact PRMT functions and cellular physiology. Our review aims to summarize molecular action mechanisms of these PRMT inhibitors and particularly elaborate their triggered biomedical effects. We describe the cellular phenotype consequences of select PRMT inhibitors across various disease models, thereby providing an understanding of the pharmacological mechanisms underpinning PRMT inhibition. The promising effects of PRMT5 inhibitors in targeted therapy of methylthioadenosine phosphorylase-deleted cancers are particularly highlighted. At last, we provide a perspective on the challenges and further opportunities of developing and applying novel PRMT inhibitors for clinical advancement.

The uncharacterized protein ZNF200 interacts with PRMT3 and aids its stability and nuclear translocation

Protein arginine methyltransferase 3 (PRMT3), a type I arginine methyltransferase is localized predominantly in the cytoplasm and regulates different cellular functions. Nevertheless, PRMT3 also exhibits regulatory functions in the nucleus by interacting with the liver X receptor alpha (LXRα) and catalyzes asymmetric dimethylation modifications at arginine 3 of histone 4 (H4R3me2a). However, very little is known about the regulation of the versatile global regulator PRMT3 and how PRMT3 is translocated to the nucleus. In this study, we identified ZNF200, a hitherto uncharacterized protein, as a potential binding partner of PRMT3 through yeast two-hybrid screening. We confirmed the interaction of PRMT3 with ZNF200 using immunoprecipitation and in vitro pull-down experiments. GST pull-down experiments and molecular docking studies revealed that the N-terminal zinc finger domain of PRMT3 binds to the C-terminal zinc finger regions of ZNF200. Furthermore, the evolutionary conservation of the Znf domain of PRMT3 correlates with the emergence of ZNF200 in mammals. We found that ZNF200 stabilizes PRMT3 by inhibiting its proteasomal degradation. ZNF200, a nuclear-predominant protein, promotes the nuclear translocation of PRMT3, leading to the global increase of H4R3me2a modifications. These findings imply that ZNF200 is a critical regulator of the steady-state levels and nuclear and epigenetic functions of PRMT3.

Unlocking the potential of histone modification in regulating bone metabolism

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

Metabolites and metabolism in vascular calcification: links between adenosine signaling and the methionine cycle

The global population of individuals with cardiovascular disease is expanding, and a key risk factor for major adverse cardiovascular events is vascular calcification. The pathogenesis of cardiovascular calcification is complex and multifaceted, with external cues driving epigenetic, transcriptional, and metabolic changes that promote vascular calcification. This review provides an overview of some of the lesser understood molecular processes involved in vascular calcification and discusses the links between calcification pathogenesis and aspects of adenosine signaling and the methionine pathway; the latter of which salvages the essential amino acid methionine, but also provides the substrate critical for methylation, a modification that regulates the function and activity of DNA and proteins. We explore the complex and dynamic nature of osteogenic reprogramming underlying intimal atherosclerotic calcification and medial arterial calcification (MAC). Atherosclerotic calcification is more widely studied; however, emerging studies now show that MAC is a significant pathology independent from atherosclerosis. Furthermore, we emphasize metabolite and metabolic-modulating factors that influence vascular calcification pathogenesis. Although the contributions of these mechanisms are more well-define in relation to atherosclerotic intimal calcification, understanding these pathways may provide crucial mechanistic insights into MAC and inform future therapeutic approaches. Herein, we highlight the significance of adenosine and methyltransferase pathways as key regulators of vascular calcification pathogenesis.

Beyond the Spectrum: Subtype-Specific Molecular Insights into Autism Spectrum Disorder Via Multimodal Data Integration

Some toddlers with autism spectrum disorder (ASD) have mild social symptoms and developmental improvement in skills, but for others, symptoms and abilities are moderately or even severely affected. Those with profound autism have the most severe social, language, and cognitive symptoms and are at the greatest risk of having a poor developmental outcome. The little that is known about the underlying biology of this important profound autism subtype, points clearly to embryonic dysregulation of proliferation, differentiation and neurogenesis. Because it is essential to gain foundational knowledge of the molecular biology associated with profound, moderate, and mild autism clinical subtypes, we used well-validated, data-driven patient subtyping methods to integrate clinical and molecular data at 1 to 3 years of age in a cohort of 363 ASD and controls representative of the general pediatric population in San Diego County. Clinical data were diagnostic, language, cognitive and adaptive ability scores. Molecular measures were 50 MSigDB Hallmark gene pathway activity scores derived from RNAseq gene expression. Subtyping identified four ASD, typical and mixed diagnostic clusters. 93% of subjects in one cluster were profound autism and 93% in a different cluster were control toddlers; a third cluster was 76% moderate ability ASD; and the last cluster was a mix of mild ASD and control toddlers. Among the four clusters, the profound autism subtype had the most severe social symptoms, language, cognitive, adaptive, social attention eye tracking, social fMRI activation, and age-related decline in abilities, while mild autism toddlers mixed within typical and delayed clusters had mild social symptoms, and neurotypical language, cognitive and adaptive scores that improved with age compared with profound and moderate autism toddlers in other clusters. In profound autism, 7 subtype-specific dysregulated gene pathways were found; they control embryonic proliferation, differentiation, neurogenesis, and DNA repair. To find subtype-common dysregulated pathways, we compared all ASD vs TD and found 17 ASD subtype-common dysregulated pathways. These common pathways showed a severity gradient with the greatest dysregulation in profound and least in mild. Collectively, results raise the new hypothesis that the continuum of ASD heterogeneity is moderated by subtype-common pathways and the distinctive nature of profound autism is driven by the differentially added profound subtype-specific embryonic pathways.

Histone Arginine Methylation as a Regulator of Gene Expression in the Dehydrating African Clawed Frog (Xenopus laevis)

The African clawed frog (Xenopus laevis) endures prolonged periods of dehydration while estivating underground during the dry season. Epigenetic modifications play crucial roles in regulating gene expression in response to environmental changes. The elucidation of epigenetic changes relevant to survival could serve as a basis for further studies on organ preservation under extreme stress. The current study examined the relative protein levels of key enzymes involved in the arginine methylation of histones in the liver and kidney tissues of control versus dehydrated (35 ± 1%) X. laevis through immunoblotting. Protein arginine methyltransferases (PRMT) 4, 5, and 6 showed significant protein level decreases of 35 ± 3%, 71 ± 7%, and 25 ± 5%, respectively, in the liver tissues of the dehydrated frogs relative to controls. In contrast, PRMT7 exhibited an increase of 36 ± 4%. Similarly, the methylated histone markers H3R2m2a, H3R8m2a, and H3R8m2s were downregulated by 34 ± 11%, 15 ± 4%, and 42 ± 12%, respectively, in the livers of dehydrated frogs compared to controls. By contrast, the kidneys of dehydrated frogs showed an upregulation of histone markers. H3R2m2a, H3R8m2a, H3R8m2s, and H4R3m2a were significantly increased by 126 ± 12%, 112 ± 7%, 47 ± 13%, and 13 ± 3%, respectively. These changes can play vital roles in the metabolic reorganization of X. laevis during dehydration, and are likely to increase the chances of survival. In turn, the tissue-specific regulation of the histone arginine methylation mechanism suggests the importance of epigenetic regulation in the adaptation of X. laevis for whole-body dehydration.

Relationship between arginine methylation and vascular calcification

In patients on maintenance hemodialysis (MHD), vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD), which is the primary cause of death in chronic kidney disease (CKD). The main component of VC in CKD is the vascular smooth muscle cells (VSMCs). VC is an ordered, dynamic activity. Under the stresses of oxidative stress and calcium-‑phosphorus imbalance, VSMCs undergo osteogenic phenotypic transdifferentiation, which promotes the formation of VC. In addition to traditional epigenetics like RNA and DNA control, post-translational modifications have been discovered to be involved in the regulation of VC in recent years. It has been reported that the process of osteoblast differentiation is impacted by catalytic histone or non-histone arginine methylation. Its function in the osteogenic process is comparable to that of VC. Thus, we propose that arginine methylation regulates VC via many signaling pathways, including as NF-B, WNT, AKT/PI3K, TGF-/BMP/SMAD, and IL-6/STAT3. It might also regulate the VC-related calcification regulatory factors, oxidative stress, and endoplasmic reticulum stress. Consequently, we propose that arginine methylation regulates the calcification of the arteries and outline the regulatory mechanisms involved.

Yifei Sanjie formula alleviates lung cancer progression via regulating PRMT6-YBX1-CDC25A axis

Lung cancer (LC) is the most prevalent cancer type, with a high mortality rate worldwide. The current treatment options for LC have not been particularly successful in improving patient outcomes. Yifei Sanjie (YFSJ), a well-applicated traditional Chinese medicine formula, is widely used to treat pulmonary diseases, especially LC, yet little is known about its molecular mechanisms. This study was conducted to explore the molecular mechanism by which YFSJ ameliorated LC progression. The A549, NCI-H1975, and Calu-3 cells were treated with the YFSJ formula and observed for colony number, apoptosis, migration, and invasion properties recorded via corresponding assays. The PRMT6-YBX1-CDC25A axis was tested and verified through luciferase reporter, RNA immunoprecipitation, and chromatin immunoprecipitation assays and rescue experiments. Our results demonstrated that YFSJ ameliorated LC cell malignant behaviors by increasing apoptosis and suppressing proliferation, migration, and invasion processes. We also noticed that the xenograft mouse model treated with YFSJ significantly reduced tumor growth compared with the control untreated group in vivo. Mechanistically, it was found that YFSJ suppressed the expression of PRMT6, YBX1, and CDC25A, while the knockdown of these proteins significantly inhibited colony growth, migration, and invasion, and boosted apoptosis in LC cells. In summary, our results suggest that YFSJ alleviates LC progression via the PRMT6-YBX1-CDC25A axis, confirming its efficacy in clinical use. The findings of our study provide a new regulatory network for LC growth and metastasis, which could shed new insights into pulmonary medical research.

Protein arginine methyltransferase 1, a major regulator of biological processes

Protein arginine methyltransferase 1 (PRMT1) is a major type I arginine methyltransferase that catalyzes the formation of monomethyl and asymmetric dimethylarginine in protein substrates. It was first identified to asymmetrically methylate histone H4 at the third arginine residue forming the H4R3me2a active histone mark. However, several protein substrates are now identified as being methylated by PRMT1. As a result of its association with diverse classes of substrates, PRMT1 regulates several biological processes like chromatin dynamics, transcription, RNA processing, and signal transduction. The review provides an overview of PRMT1 structure, biochemical features, specificity, regulation, and role in cellular functions. We discuss the genomic distribution of PRMT1 and its association with tRNA genes. Further, we explore the different substrates of PRMT1 involved in splicing. In the end, we discuss the proteins that interact with PRMT1 and their downstream effects in diseased states.

Epigenetic regulators controlling osteogenic lineage commitment and bone formation

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

PRMT3 methylates HIF-1α to enhance the vascular calcification induced by chronic kidney disease

BACKGROUND

Medial vascular calcification is commonly identified in chronic kidney disease (CKD) patients and seriously affects the health and life quality of patients. This study aimed to investigate the effects of protein arginine methyltransferase 3 (PRMT3) on vascular calcification induced by CKD.

METHODS

A mice model of CKD was established with a two-step diet containing high levels of calcium and phosphorus. Vascular smooth muscle cells (VSMCs) were subjected to β-glycerophosphate (β-GP) treatment to induce the osteogenic differentiation as an in vitro CKD model.

RESULTS

PRMT3 was upregulated in VSMCs of medial artery of CKD mice and β-GP-induced VSMCs. The inhibitor of PRMT3 (SGC707) alleviated the vascular calcification and inhibited the glycolysis of CKD mice. Knockdown of PRMT3 alleviated the β-GP-induced osteogenic transfomation of VSMCs by the repression of glycolysis. Next, PRMT3 interacted with hypoxia-induced factor 1α (HIF-1α), and the knockdown of PRMT3 downregulated the protein expression of HIF-1α by weakening its methylation. Gain of HIF-1α reversed the PRMT3 depletion-induced suppression of osteogenic differentiation and glycolysis of VSMCs.

CONCLUSION

The inhibitory role of PRMT3 depletion was at least mediated by the regulation of glycolysis upon repressing the methylation of HIF-1α.

An Updated Review on the Significance of DNA and Protein Methyltransferases and De-methylases in Human Diseases: From Molecular Mechanism to Novel Therapeutic Approaches

Epigenetic mechanisms are crucial in regulating gene expression. These mechanisms include DNA methylation and histone modifications, like methylation, acetylation, and phosphorylation. DNA methylation is associated with gene expression suppression; however, histone methylation can stimulate or repress gene expression depending on the methylation pattern of lysine or arginine residues on histones. These modifications are key factors in mediating the environmental effect on gene expression regulation. Therefore, their aberrant activity is associated with the development of various diseases. The current study aimed to review the significance of DNA and histone methyltransferases and demethylases in developing various conditions, like cardiovascular diseases, myopathies, diabetes, obesity, osteoporosis, cancer, aging, and central nervous system conditions. A better understanding of the epigenetic roles in developing diseases can pave the way for developing novel therapeutic approaches for affected patients.

Promising role of protein arginine methyltransferases in overcoming anti-cancer drug resistance

Drug resistance remains a major challenge in cancer treatment, necessitating the development of novel strategies to overcome it. Protein arginine methyltransferases (PRMTs) are enzymes responsible for epigenetic arginine methylation, which regulates various biological and pathological processes, as a result, they are attractive therapeutic targets for overcoming anti-cancer drug resistance. The ongoing development of small molecules targeting PRMTs has resulted in the generation of chemical probes for modulating most PRMTs and facilitated clinical treatment for the most advanced oncology targets, including PRMT1 and PRMT5. In this review, we summarize various mechanisms underlying protein arginine methylation and the roles of specific PRMTs in driving cancer drug resistance. Furthermore, we highlight the potential clinical implications of PRMT inhibitors in decreasing cancer drug resistance. PRMTs promote the formation and maintenance of drug-tolerant cells via several mechanisms, including altered drug efflux transporters, autophagy, DNA damage repair, cancer stem cell-related function, epithelial-mesenchymal transition, and disordered tumor microenvironment. Multiple preclinical and ongoing clinical trials have demonstrated that PRMT inhibitors, particularly PRMT5 inhibitors, can sensitize cancer cells to various anti-cancer drugs, including chemotherapeutic, targeted therapeutic, and immunotherapeutic agents. Combining PRMT inhibitors with existing anti-cancer strategies will be a promising approach for overcoming anti-cancer drug resistance. Furthermore, enhanced knowledge of the complex functions of arginine methylation and PRMTs in drug resistance will guide the future development of PRMT inhibitors and may help identify new clinical indications.

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

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

MiR-224-5p inhibits osteoblast differentiation and impairs bone formation by targeting Runx2 and Sp7

Osteoporosis is a complicated multifactorial disorder characterized by low bone mass and deteriorated bone microarchitecture with an elevated fracture risk. MicroRNAs play important roles in osteoblastic differentiation. In the present study, we found that miR-224-5p was markedly downregulated during the osteogenic differentiation of C2C12 cells. Overexpression of miR-224-5p in C2C12 cells inhibited osteoblast activity, as indicated by reduced ALP activity, matrix mineralization and the expression of osteogenic marker genes. Moreover, we demonstrated that Runx2 and Sp7 were direct targets of miR-224-5p. Furthermore, the specific inhibition of miR-224-5p by femoral bone marrow cavity injection with miR-224-5p antagomir prevented ovariectomy-induced bone loss. Finally, we found that the levels of miR-224-5p were markedly elevated in the sera of patients with osteoporosis. Collectively, this study revealed that miR-224-5p negatively regulates osteogenic differentiation by targeting Runx2 and Sp7. It also highlights the potential use of miR-224-5p as a therapeutic target and diagnostic biomarker for osteoporosis.

Supplementary information

The online version contains supplementary material available at 10.1007/s10616-023-00593-z.

Protein arginine methylation in viral infection and antiviral immunity

Protein arginine methyltransferase (PRMT)-mediated arginine methylation is an important post-transcriptional modification that regulates various cellular processes including epigenetic gene regulation, genome stability maintenance, RNA metabolism, and stress-responsive signal transduction. The varying substrates and biological functions of arginine methylation in cancer and neurological diseases have been extensively discussed, providing a rationale for targeting PRMTs in clinical applications. An increasing number of studies have demonstrated an interplay between arginine methylation and viral infections. PRMTs have been found to methylate and regulate several host cell proteins and different functional types of viral proteins, such as viral capsids, mRNA exporters, transcription factors, and latency regulators. This modulation affects their activity, subcellular localization, protein-nucleic acid and protein-protein interactions, ultimately impacting their roles in various virus-associated processes. In this review, we discuss the classification, structure, and regulation of PRMTs and their pleiotropic biological functions through the methylation of histones and non-histones. Additionally, we summarize the broad spectrum of PRMT substrates and explore their intricate effects on various viral infection processes and antiviral innate immunity. Thus, comprehending the regulation of arginine methylation provides a critical foundation for understanding the pathogenesis of viral diseases and uncovering opportunities for antiviral therapy.

Critical Roles of Protein Arginine Methylation in the Central Nervous System

A remarkable post-transitional modification of both histones and non-histone proteins is arginine methylation. Methylation of arginine residues is crucial for a wide range of cellular process, including signal transduction, DNA repair, gene expression, mRNA splicing, and protein interaction. Arginine methylation is modulated by arginine methyltransferases and demethylases, like protein arginine methyltransferase (PRMTs) and Jumonji C (JmjC) domain containing (JMJD) proteins. Symmetric dimethylarginine and asymmetric dimethylarginine, metabolic products of the PRMTs and JMJD proteins, can be changed by abnormal expression of these proteins. Many pathologies including cancer, inflammation and immune responses have been closely linked to aberrant arginine methylation. Currently, the majority of the literature discusses the substrate specificity and function of arginine methylation in the pathogenesis and prognosis of cancers. Numerous investigations on the roles of arginine methylation in the central nervous system (CNS) have so far been conducted. In this review, we display the biochemistry of arginine methylation and provide an overview of the regulatory mechanism of arginine methyltransferases and demethylases. We also highlight physiological functions of arginine methylation in the CNS and the significance of arginine methylation in a variety of neurological diseases such as brain cancers, neurodegenerative diseases and neurodevelopmental disorders. Furthermore, we summarize PRMT inhibitors and molecular functions of arginine methylation. Finally, we pose important questions that require further research to comprehend the roles of arginine methylation in the CNS and discover more effective targets for the treatment of neurological diseases.

BHLHE40 Maintains the Stemness of PαS Cells In Vitro by Targeting Zbp1 through the Wnt/β-Catenin Signaling Pathway

Primary bone mesenchymal stem cells (BMSCs) gradually lose stemness during in vitro expansion, which significantly affects the cell therapeutic effects. Here, we chose murine PαS (SCA-1+PDGFRα+CD45-TER119-) cells as representative of BMSCs and aimed to explore the premium culture conditions for PαS cells. Freshly isolated (fresh) PαS cells were obtained from the limbs of C57/6N mice by fluorescence-activated cell sorting (FACS). We investigated the differences in the stemness of PαS cells by proliferation, differentiation, and stemness markers in vitro and by ectopic osteogenesis and chondrogenesis ability in vivo, as well as the changes in the stemness of PαS cells during expansion in vitro. Gain- and loss-of-function experiments were applied to investigate the critical role and underlying mechanism of the basic helix-loop-helix family member E40 (BHLHE40) in maintaining the stemness of PαS cells. The stemness of fresh PαS cells representative in vivo was superior to that of passage 0 (P0) PαS cells in vitro. The stemness of PαS cells in vitro decreased gradually from P0 to passage 4 (P4). Moreover, BHLHE40 plays a critical role in regulating the stemness of PαS cells during in vitro expansion. Mechanically, BHLHE40 regulates the stemness of PαS cells by targeting Zbp1 through the Wnt/β-catenin signaling pathway. This work confirms that BHLHE40 is a critical factor for regulating the stemness of PαS cells during expansion in vitro and may provide significant indications in the exploration of premium culture conditions for PαS cells.

Feasibility of an acoustophoresis-based system for a high-throughput cell washing: application to bioproduction

BACKGROUND AIMS

These last decades have seen the emergence and development of cell-based therapies, notably those based on mesenchymal stromal cells (MSCs). The advancement of these promising treatments requires increasing the throughput of processed cell for industrialization in order to reduce production costs. Among the various bioproduction challenges, downstream processing, including medium exchange, cell washing, cell harvesting and volume reduction, remains a critical step for which improvements are needed. Typically, these processes are performed by centrifugation. However, this approach limits the automation, especially in small batch productions where it is performed manually in open system.

METHODS

An acoustophoresis-based system was developed for cell washing. The cells were transferred from one stream to another via the acoustic forces and were collected in a different medium. The optimal flow rates of the different streams were assessed using red blood cells suspended in an albumin solution. Finally, the impact of acoustic washing on adipose tissue-derived MSCs (AD-MSCs) transcriptome was investigated by RNA-sequencing.

RESULTS

With a single passage through the acoustic device at input flow rate of 45 mL/h, the albumin removal was up to 90% while recovering 99% of RBCs. To further increase the protein removal, a loop washing in two steps was performed and has allowed an albumin removal ≥99% and a red blood cell/AD-MSCs recovery of 99%. After loop washing of AD-MSCs, only two genes, HES4 and MIR-3648-1, were differently expressed compared with the input.

CONCLUSIONS

In this study, we developed a continuous cell-washing system based on acoustophoresis. The process allows a theoretically high cell throughput while inducing little gene expression changes. These results indicate that cell washing based on acoustophoresis is a relevant and promising solution for numerous applications in cell manufacturing.

Dysregulation of histone modifications in bone marrow mesenchymal stem cells during skeletal ageing: roles and therapeutic prospects

Age-associated bone diseases such as osteoporosis (OP) are common in the elderly due to skeletal ageing. The process of skeletal ageing can be accelerated by reduced proliferation and osteogenesis of bone marrow mesenchymal stem cells (BM-MSCs). Senescence of BM-MSCs is a main driver of age-associated bone diseases, and the fate of BM-MSCs is tightly regulated by histone modifications, such as methylation and acetylation. Dysregulation of histone modifications in BM-MSCs may activate the genes related to the pathogenesis of skeletal ageing and age-associated bone diseases. Here we summarize the histone methylation and acetylation marks and their regulatory enzymes that affect BM-MSC self-renewal, differentiation and senescence. This review not only describes the critical roles of histone marks in modulating BM-MSC functions, but also underlines the potential of epigenetic enzymes as targets for treating age-associated bone diseases. In the future, more effective therapeutic approaches based on these epigenetic targets will be developed and will benefit elderly individuals with bone diseases, such as OP.

Dissection of a Down syndrome-associated trisomy to separate the gene dosage-dependent and -independent effects of an extra chromosome

As an aneuploidy, trisomy is associated with mammalian embryonic and postnatal abnormalities. Understanding the underlying mechanisms involved in mutant phenotypes is broadly important and may lead to new strategies to treat clinical manifestations in individuals with trisomies, such as trisomy 21 [Down syndrome (DS)]. Although increased gene dosage effects because of a trisomy may account for the mutant phenotypes, there is also the possibility that phenotypic consequences of a trisomy can arise because of the presence of a freely segregating extra chromosome with its own centromere, i.e. a 'free trisomy' independent of gene dosage effects. Presently, there are no reports of attempts to functionally separate these two types of effects in mammals. To fill this gap, here we describe a strategy that employed two new mouse models of DS, Ts65Dn;Df(17)2Yey/+ and Dp(16)1Yey/Df(16)8Yey. Both models carry triplications of the same 103 human chromosome 21 gene orthologs; however, only Ts65Dn;Df(17)2Yey/+ mice carry a free trisomy. Comparison of these models revealed the gene dosage-independent impacts of an extra chromosome at the phenotypic and molecular levels for the first time. They are reflected by impairments of Ts65Dn;Df(17)2Yey/+ males in T-maze tests when compared with Dp(16)1Yey/Df(16)8Yey males. Results from the transcriptomic analysis suggest the extra chromosome plays a major role in trisomy-associated expression alterations of disomic genes beyond gene dosage effects. This model system can now be used to deepen our mechanistic understanding of this common human aneuploidy and obtain new insights into the effects of free trisomies in other human diseases such as cancers.

Protein arginine methyltransferase 3: A crucial regulator in metabolic reprogramming and gene expression in cancers

Post-translational modification (PTM) of proteins increases proteome diversity, which is critical for maintaining cellular homeostasis. The importance of protein methylation in the regulation of diverse biological processes has been highlighted in the past decades. Methylation of the arginine residue on proteins is catalyzed by members of the protein arginine methyltransferase (PRMT) family. PRMTs play indispensable roles in various pathways that regulate cancer development, progression, and drug response. In this review, we discuss the role of PRMT3, a member of the PRMT family, in controlling oncogenic processes. Additionally, the effects of PRMT3 on the methylation of regulatory proteins involved in transcription, post-transcriptional control, ribosomal maturation, translation, biological synthesis, and metabolic signaling are summarized. Moreover, recent progresses in the development of PRMT3 inhibitors are introduced. Overall, this review highlights the importance of PRMT3 in tumorigenesis and discusses the underlying mechanisms by which PRMT3 modulates cellular metabolism and gene expression. These results also provide a molecular basis for therapeutic modalities by targeting PRMT3.

Epigenetics: Novel crucial approach for osteogenesis of mesenchymal stem cells

Bone has a robust regenerative potential, but its capacity to repair critical-sized bone defects is limited. In recent years, stem cells have attracted significant interest for their potential in tissue engineering. Applying mesenchymal stem cells (MSCs) for enhancing bone regeneration is a promising therapeutic strategy. However, maintaining optimal cell efficacy or viability of MSCs is limited by several factors. Epigenetic modification can cause changes in gene expression levels without changing its sequence, mainly including nucleic acids methylation, histone modification, and non-coding RNAs. This modification is believed to be one of the determinants of MSCs fate and differentiation. Understanding the epigenetic modification of MSCs can improve the activity and function of stem cells. This review summarizes recent advances in the epigenetic mechanisms of MSCs differentiation into osteoblast lineages. We expound that epigenetic modification of MSCs can be harnessed to treat bone defects and promote bone regeneration, providing potential therapeutic targets for bone-related diseases.

The PCK2-glycolysis axis assists three-dimensional-stiffness maintaining stem cell osteogenesis

Understanding mechanisms underlying the heterogeneity of multipotent stem cells offers invaluable insights into biogenesis and tissue development. Extracellular matrix (ECM) stiffness has been acknowledged as a crucial factor regulating stem cell fate. However, how cells sense stiffness cues and adapt their metabolism activity is still unknown. Here we report the novel role of mitochondrial phosphoenolpyruvate carboxykinase (PCK2) in enhancing osteogenesis in 3D ECM via glycolysis. We experimentally mimicked the physical characteristics of 3D trabeculae network of normal and osteoporotic bone with different microstructure and stiffness, observing that PCK2 promotes osteogenesis in 3D ECM with tunable stiffness in vitro and in vivo. Mechanistically, PCK2 enhances the rate-limiting metabolic enzyme pallet isoform phosphofructokinase (PFKP) in 3D ECM, and further activates AKT/extracellular signal-regulated kinase 1/2 (ERK1/2) cascades, which directly regulates osteogenic differentiation of MSCs. Collectively, our findings implicate an intricate crosstalk between cell mechanics and metabolism, and provide new perspectives for strategies of osteoporosis.

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As the key rate-limiting enzyme of gluconeogenesis, PCK2 manipulates osteogenesis in stiff and soft ECM in vitro and in vivo.

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PCK2 regulates osteogenic capacity of BMMSCs in 3D ECM with different stiffness, via modulating glycolysis and regulating PFKP-AKT/ERK signaling pathways.

Protein Arginine Methyltransferases as Therapeutic Targets in Hematological Malignancies

Arginine methylation is a common post-translational modification affecting protein activity and the transcription of target genes when methylation occurs on histone tails. There are nine protein arginine methyltransferases (PRMTs) in mammals, divided into subgroups depending on the methylation they form on a molecule of arginine. During the formation and maturation of the different types of blood cells, PRMTs play a central role by controlling cell differentiation at the transcriptional level. PRMT enzymatic activity is necessary for many cellular processes in hematological malignancies, such as the activation of cell cycle and proliferation, inhibition of apoptosis, DNA repair processes, RNA splicing, and transcription by methylating histone tails' arginine. Chemical tools have been developed to inhibit the activity of PRMTs and have been tested in several models of hematological malignancies, including primary samples from patients, xenografts into immunodeficient mice, mouse models, and human cell lines. They show a significant effect by reducing cell viability and increasing the overall survival of mice. PRMT5 inhibitors have a strong therapeutic potential, as phase I clinical trials in hematological malignancies that use these molecules show promising results, thus, underlining PRMT inhibitors as useful therapeutic tools for cancer treatment in the future.

The miR-3648/FRAT1-FRAT2/c-Myc negative feedback loop modulates the metastasis and invasion of gastric cancer cells

Although the abnormal expression of miRNAs in cancer cells is a widely accepted phenomenon, the molecular mechanisms underlying miR-3648 progression and metastasis in gastric cancer (GC) remain unclear. miR-3648 expression is downregulated and its ectopic expression in GC cells significantly suppressed cell proliferation and metastasis. Mechanistic analyses indicated that miR-3648 directly targets FRAT1 or FRAT2 and inhibits FRAT1- or FRAT2-mediated invasion and motility in vitro and in vivo. Moreover, FRAT1 physically interacted with FRAT2. Furthermore, FRAT1 overexpression promoted GC cell invasion, whereas siRNA-mediated repression of FRAT2 in FRAT1-overexpressing GC cells reversed its invasive potential. Besides, miR-3648 inactivated the Wnt/β-catenin signalling pathway by downregulating FRAT1 and FRAT2 in GC. Interestingly, c-Myc, a downstream effector of Wnt/β-catenin signalling, was also downregulated by miR-3648 overexpression. In turn, c-Myc negatively regulated miR-3648 expression by binding to the miR-3648 promoter. In addition, miR-3648 expression levels were negatively correlated with c-Myc, FRAT1, and FRAT2 expression in fresh gastric samples. Our studies suggest that miR-3648 acts as a tumour-suppressive miRNA and that the miR-3648/FRAT1-FRAT2/c-Myc negative feedback loop could be a critical regulator of GC progression.

MicroRNA-loaded biomaterials for osteogenesis

The large incidence of bone defects in clinical practice increases not only the demand for advanced bone transplantation techniques but also the development of bone substitute materials. A variety of emerging bone tissue engineering materials with osteogenic induction ability are promising strategies for the design of bone substitutes. MicroRNAs (miRNAs) are a class of non-coding RNAs that regulate intracellular protein expression by targeting the non-coding region of mRNA3′-UTR to play an important role in osteogenic differentiation. Several miRNA preparations have been used to promote the osteogenic differentiation of stem cells. Therefore, multiple functional bone tissue engineering materials using miRNA as an osteogenic factor have been developed and confirmed to have critical efficacy in promoting bone repair. In this review, osteogenic intracellular signaling pathways mediated by miRNAs are introduced in detail to provide a clear understanding for future clinical treatment. We summarized the biomaterials loaded with exogenous cells engineered by miRNAs and biomaterials directly carrying miRNAs acting on endogenous stem cells and discussed their advantages and disadvantages, providing a feasible method for promoting bone regeneration. Finally, we summarized the current research deficiencies and future research directions of the miRNA-functionalized scaffold. This review provides a summary of a variety of advanced miRNA delivery system design strategies that enhance bone regeneration.

Histone Modifications and Non-Coding RNAs: Mutual Epigenetic Regulation and Role in Pathogenesis

In the last few years, more and more scientists have suggested and confirmed that epigenetic regulators are tightly connected and form a comprehensive network of regulatory pathways and feedback loops. This is particularly interesting for a better understanding of processes that occur in the development and progression of various diseases. Appearing on the preclinical stages of diseases, epigenetic aberrations may be prominent biomarkers. Being dynamic and reversible, epigenetic modifications could become targets for a novel option for therapy. Therefore, in this review, we are focusing on histone modifications and ncRNAs, their mutual regulation, role in cellular processes and potential clinical application.

Protein arginine methyltransferase 3 promotes glycolysis and hepatocellular carcinoma growth by enhancing arginine methylation of lactate dehydrogenase A

BACKGROUND

Protein arginine methylation has emerged a pivotal role in cancer progression. However, the role of protein arginine methyltransferase 3 (PRMT3) in hepatocellular carcinoma (HCC) remains unknown.

METHODS

The expression pattern of PRMT3 in HCC was analysed using quantitative real-time-polymerase chain reaction (qRT-PCR), Western blotting and immunohistochemistry assays. Loss- and gain-of-function experiments were carried out to determine the oncogenic role of PRMT3 in HCC. Glucose consumption and lactate production assays, seahorse bioscience, mass spectrometry, co-immunoprecipitation, metabonomic analysis and site-specific mutation experiments were used to explore the underlying molecular mechanisms. Furthermore, a xenograft mouse model was established to investigate the effects of PRMT3 and its inhibitor, SGC707, treatment on tumour growth in vivo.

RESULTS

The expression of PRMT3 was significantly upregulated in HCC, with high expression of which correlated with poor prognosis. PRMT3 knockdown led to the decrease in proliferation, glycolysis of HCC cells and tumour growth, whilst its overexpression showed opposite results. The catalytic activity of PRMT3 was important in mediating these biological processes. Mechanistically, our data showed that PRMT3 interacted with and mediated asymmetric dimethylarginine (ADMA) modification of lactate dehydrogenase A (LDHA) at arginine 112 (R112). Compared with LDHA-wild-type (LDHA-WT) cells, LDHA-R112K-mutant-expressing HCC cells exhibited a decrease in lactate dehydrogenase (LDH) activity, HCC cell glycolysis and proliferation. Furthermore, the administration of SGC707, a selective inhibitor of PRMT3, disrupted the PRMT3-mediated LDHA methylation and abolished PRMT3-induced HCC glycolysis and tumour growth.

CONCLUSIONS

Our results suggested a novel oncogenic role of PRMT3 in HCC, and it could be a promising therapeutic target for HCC by linking post-translational modification and cancer metabolism.

The impact of non-coding RNAs on normal stem cells

Self-renewal and differentiation into diverse cells are two main characteristics of stem cells. These cells have important roles in development and homeostasis of different tissues and are supposed to facilitate tissue regeneration. Function of stem cells is regulated by dynamic interactions between external signaling, epigenetic factors, and molecules that regulate expression of genes. Among the highly appreciated regulators of function of stem cells are long non-coding RNAs (lncRNAs) and microRNAs (miRNAs). Impact of miR-342-5p, miR-145, miR-1297, miR-204-5p, miR-132, miR-128-3p, hsa-miR-302, miR-26b-5p and miR-10a are among miRNAs that regulate function of stem cells. Among lncRNAs, AK141205, ANCR, MEG3, Pnky, H19, TINCR, HULC, EPB41L4A-AS1 and SNHG7 have important roles in the regulation of stem cells. In the current paper, we aimed at reviewing the importance of miRNAs and lncRNAs in differentiation of stem cells both in normal and diseased conditions. For this purpose, we searched PubMed/Medline and google scholar databases using "stem cell" AND "lncRNA", or "long non-coding RNA", or "microRNA" or "miRNA".

Contribution of miRNAs and lncRNAs in osteogenesis and related disorders

Non-coding RNAs have been found to regulate several developmental processes among them is osteogenesis. Although these transcripts have several distinct classes, two classes i.e. microRNAs and long non-coding RNAs have attained more attention. These transcripts regulate intramembranous as well as endochondral ossification processes. The effects of microRNAs on osteogenesis are mostly mediated through modulation of Wnt/β-catenin and TGFβ/BMP pathways. Long non-coding RNAs can directly affect expression of these pathways or osteogenic transcription factors. Moreover, they can serve as a molecular sponge for miRNAs. MALAT1/miR-30, MALAt1/miR-214, LEF1-AS1/miR-24-3p, MCF2L-AS1/miR-33a, MSC-AS1/miR-140-5p and KCNQ1OT1/miR-214 are examples of such kind of interaction between lncRNAs and miRNAs in the context of osteogenesis. In the current paper, we explain these two classes of non-coding RNAs in the osteogenesis and related disorders.

Protein arginine methylation: from enigmatic functions to therapeutic targeting

Protein arginine methyltransferases (PRMTs) are emerging as attractive therapeutic targets. PRMTs regulate transcription, splicing, RNA biology, the DNA damage response and cell metabolism; these fundamental processes are altered in many diseases. Mechanistically understanding how these enzymes fuel and sustain cancer cells, especially in specific metabolic contexts or in the presence of certain mutations, has provided the rationale for targeting them in oncology. Ongoing inhibitor development, facilitated by structural biology, has generated tool compounds for the majority of PRMTs and enabled clinical programmes for the most advanced oncology targets, PRMT1 and PRMT5. In-depth mechanistic investigations using genetic and chemical tools continue to delineate the roles of PRMTs in regulating immune cells and cancer cells, and cardiovascular and neuronal function, and determine which pathways involving PRMTs could be synergistically targeted in combination therapies for cancer. This research is enhancing our knowledge of the complex functions of arginine methylation, will guide future clinical development and could identify new clinical indications.

Protein arginine methyltransferases: promising targets for cancer therapy

Protein methylation, a post-translational modification (PTM), is observed in a wide variety of cell types from prokaryotes to eukaryotes. With recent and rapid advancements in epigenetic research, the importance of protein methylation has been highlighted. The methylation of histone proteins that contributes to the epigenetic histone code is not only dynamic but is also finely controlled by histone methyltransferases and demethylases, which are essential for the transcriptional regulation of genes. In addition, many nonhistone proteins are methylated, and these modifications govern a variety of cellular functions, including RNA processing, translation, signal transduction, DNA damage response, and the cell cycle. Recently, the importance of protein arginine methylation, especially in cell cycle regulation and DNA repair processes, has been noted. Since the dysregulation of protein arginine methylation is closely associated with cancer development, protein arginine methyltransferases (PRMTs) have garnered significant interest as novel targets for anticancer drug development. Indeed, several PRMT inhibitors are in phase 1/2 clinical trials. In this review, we discuss the biological functions of PRMTs in cancer and the current development status of PRMT inhibitors in cancer therapy.

Arginine methyltransferase PRMT3 promote tumorigenesis through regulating c-MYC stabilization in colorectal cancer

The incidence rates of colorectal cancer have been increasing in the last decades, yet the overall survival rate is still not ideal. There is a need to further investigate detailed mechanism for colorectal cancer tumorigenesis. The biological function of protein arginine methyltransferases 3 (PRMT3) is seldom studied in tumorigenesis. Here, we attempted to elucidate the link between PRMT3 and tumorigenesis in colorectal cancer. Results revealed that PRMT3 was upregulated in colorectal cancer. Besides, PRMT3 overexpression promoted colorectal cancer cell proliferation, migration, and invasion. Regarding mechanism for colorectal cancer tumorigenesis, PRMT3 stabilized C-MYC and the pro-tumorigenesis function of PRMT3 was dependent on C-MYC. Clinically, these findings might provide a novel therapeutical treatment strategy for colorectal cancer.

BMSC-derived exosomes from congenital polydactyly tissue alleviate osteoarthritis by promoting chondrocyte proliferation

In the past decade, mesenchymal stem cells (MSCs) have been widely used for the treatment of osteoarthritis (OA), and exosomes may play a major role. Here, we acquired a special kind of MSCs from the bone marrow of surgically resected tissue from the hand of a patient with polydactyly. Experiments were focused on the role of polydactyly bone marrow-derived MSCs (pBMSCs) in osteoarthritis. The results showed that the pBMSCs had a greater ability than the BMSCs to differentiate into chondrocytes. Mechanistically, the expression of BMP4 was significantly higher in the pBMSCs than it was in the BMSCs. Furthermore, we showed that the migration and proliferation of chondrocytes were stimulated by exosomes secreted by pBMSC (pBMSC-EXOs). Notably, the downregulation of BMP4 in pBMSCs by siRNA inhibited both the chondrogenic differentiation potential of the MSCs and the function of the chondrocytes. In addition, the injection of pBMSC-EXOs and BMSC-EXOs attenuated OA in an OA mouse model, but the pBMSC-EXOs had a superior therapeutic effect compared with that of the BMSC-EXOs. Taken together, the data indicate that pBMSCs have greater ability to differentiate into chondrocytes and regulate chondrocyte formation through BMP4 signaling. Therefore, pBMSC-EXOs may represent a novel treatment for OA.

Ecological adaptation in Atlantic herring is associated with large shifts in allele frequencies at hundreds of loci

Atlantic herring is widespread in North Atlantic and adjacent waters and is one of the most abundant vertebrates on earth. This species is well suited to explore genetic adaptation due to minute genetic differentiation at selectively neutral loci. Here, we report hundreds of loci underlying ecological adaptation to different geographic areas and spawning conditions. Four of these represent megabase inversions confirmed by long read sequencing. The genetic architecture underlying ecological adaptation in herring deviates from expectation under a classical infinitesimal model for complex traits because of large shifts in allele frequencies at hundreds of loci under selection.

Knockdown of LAP2α inhibits osteogenic differentiation of human adipose-derived stem cells by activating NF-κB

BACKGROUND

Lamina-associated polypeptide 2α (LAP2α) is a nucleoplasmic protein that has been involved in the regulation of the cell cycle, gene transcription, and adult stem cell function. LAP2α down-regulation is linked to age-related osteoporosis and bone deformities; however, the underlying mechanisms remain obscure. The present study aimed to elucidate the function of LAP2α in the osteogenic differentiation of human adipose-derived stem cells (hASCs), which are attractive sources for bone tissue engineering.

METHODS

The expression of LAP2α during the osteogenic differentiation of hASCs was detected firstly. A loss of function investigation was then carried out to characterize the function of LAP2α in osteogenic differentiation of hASCs both in vitro and in vivo. Moreover, RNA-sequences, western blotting, and confocal analyses were performed to clarify the molecular mechanism of LAP2α-regulated osteogenesis.

RESULTS

We found that LAP2α expression was upregulated upon osteogenic induction. Both in vitro and in vivo experiments indicated that LAP2α knockdown resulted in impaired osteogenic differentiation of hASCs. Mechanistically, we revealed that LAP2α deficiency activated nuclear factor kappa B (NF-κB) signaling by controlling the cytoplasmic-nuclear translocation of p65.

CONCLUSIONS

Collectively, our findings revealed that LAP2α functions as an essential regulator for osteogenesis of hASCs by modulating NF-κB signaling, thus providing novel insights for mesenchymal stem cell-mediated bone tissue engineering.