Asymmetric Expression of LincGET Biases Cell Fate in Two-Cell Mouse Embryos.

In early mammalian embryos, it remains unclear how the first cell fate bias is initially triggered and amplified toward cell fate segregation. Here, we report that a long noncoding RNA, LincGET, is transiently and asymmetrically expressed in the nucleus of two- to four-cell mouse embryos. Overexpression of LincGET in one of the two-cell blastomeres biases its progeny predominantly toward the inner cell mass (ICM) fate. Mechanistically, LincGET physically binds to CARM1 and promotes the nuclear localization of CARM1, which can further increase the level of H3 methylation at Arginine 26 (H3R26me), activate ICM-specific gene expression, upregulate transposons, and increase global chromatin accessibility. Simultaneous overexpression of LincGET and depletion of Carm1 no longer biased embryonic fate, indicating that the effect of LincGET in directing ICM lineage depends on CARM1. Thus, our data identify LincGET as one of the earliest known lineage regulators to bias cell fate in mammalian 2-cell embryos.

Clinicopathological and Prognostic Significance of PRMT5 in Cancers: A System Review and Meta-Analysis.

PURPOSE: Since protein arginine methyltransferase 5 (PRMT5) is abnormally expressed in various tumors, in this study we aim to assess the association between PRMT5 and clinicopathological and prognostic features. METHODS: Electronic databases including PubMed, Web of Science, Scopus, ScienceDirect, and the Cochrane Library were searched until July 25, 2021. The critical appraisal of the eligible studies was performed using the Newcastle-Ottawa Quality Assessment Scale. Pooled hazard ratios (HR) and pooled odds ratios (OR) were calculated to assess the effect. Engauge Digitizer version 12.1, STATA version 15.1, and R version 4.0.5 were used to obtain and analysis the data. RESULTS: A total of 32 original studies covering 15,583 patients were included. In our data, it indicated that high level of PRMT5 was significantly correlated with advanced tumor stage (OR = 2.12, 95% CI: 1.22-3.70, P =.008; I2 = 80.7%) and positively correlated with poor overall survival (HR = 1.59, 95% CI: 1.46-1.73, P < .001; I2 = 50%) and progression-free survival (HR = 1.53, 95% CI: 1.24-1.88, P < .001; I2 = 0%). In addition, sub-group analysis showed that high level of PRMT5 was associated with poor overall survival for such 5 kinds of cancers as hepatocellular carcinoma, pancreatic cancer, breast cancer, gastric cancer, and lung cancer. CONCLUSION: For the first time we found PRMT5 was pan-cancerous as a prognostic biomarker and high level of PRMT5 was associated with poor prognosis for certain cancers.

The role of protein arginine methyltransferase 7 in human developmentally arrested embryos cultured in vitro.

Human embryos of in vitro fertilization (IVF) are often susceptible to developmental arrest, which greatly reduces the efficiency of IVF treatment. In recent years, it has been found that protein arginine methyltransferase 7 (PRMT7) plays an important role in the process of early embryonic development. However, not much is known about the relationship between PRMT7 and developmentally arrested embryos. The role of PRMT7 in developmentally arrested embryos was thus investigated in this study. Discarded human embryos from IVF were collected for experimental materials. Quantitative real-time polymerase chain reaction (qRT-PCR) and confocal analyses were used to identify PRMT7 mRNA and protein levels in early embryos at different developmental stages, as well as changes in the methylation levels of H4R3me2s. Additionally, PRMT7 was knocked down in the developmentally arrested embryos to observe the further development of these embryos. Our results demonstrated that PRMT7 mRNA and protein levels in arrested embryos were significantly increased compared with those in control embryos; meanwhile, the methylation levels of H4R3me2s in arrested embryos were also increased significantly. Knockdown of PRMT7 could rescue partially developmentally arrested embryos, and even individual developmentally arrested embryos could develop into blastocysts. In conclusion, over-expression of PRMT7 disrupts the early embryo development process, leading to early embryos developmental arrest, but these developmentally arrested defects could be partially rescued by knockdown of the PRMT7 protein.

The Effects of Flavonoid Apigenin on Male Reproductive Health: Inhibition of Spermatogonial Proliferation through Downregulation of Prmt7/Akt3 Pathway.

Apigenin, a common dietary flavonoid abundantly present in a variety of fruits and vegetables, has promising anticancer properties. As an effector of apigenin in myoblasts, protein arginine methyltransferase 7 (Prmt7) is required for male germ cell development. However, whether apigenin may influence male reproductive health through Prmt7 is still unclear. To this end, mouse spermatogonia were treated with different concentrations (2.5 to 50 µM) of apigenin for 48 h, which showed that apigenin could cause reduced cell proliferation in conjunction with longer S phase and G2/M phase (with concentrations of 10 and 20 µM, respectively), and increased apoptosis of spermatogonia (with concentration of 20 µM). Reduced Prmt7 expression was found in 20 µM apigenin-treated spermatogonia. Moreover, siRNA-induced Prmt7 knockdown exhibited similar influence on spermatogonia as that of apigenin treatment. In mechanistic terms, transcriptome analysis revealed 287 differentially expressed genes between Prmt7-downregulated and control spermatogonia. Furthermore, rescue experiments suggested that the effects of apigenin on spermatogonia might be mediated through the Prmt7/Akt3 pathway. Overall, our study supports that apigenin can interfere with mouse spermatogonial proliferation by way of the downregulated Prmt7/Akt3 pathway, which demonstrates that the concentration should be taken into account in future applications of apigenin for cancer therapy of men.

Curcumin ameliorates PRMT5-MEP50 arginine methyltransferase expression by decreasing the Sp1 and NF-YA transcription factors in the A549 and MCF-7 cells.

The protein arginine methyltransferase 5 (PRMT5) and its catalytic partner methylosome protein MEP50 (WDR77) catalyse the mono- and symmetric di-methylation of selective arginines in various histones and non-histone target proteins. It has emerged as a crucial epigenetic regulator in cell proliferation and differentiation; which also reported to be overexpressed in many forms of cancers in humans. In this study, we aimed to assess the modulations in the expression of this enzyme upon exposure to the well-studied natural compound from the spice turmeric, curcumin. We exposed the lung and breast cancer cell lines (A549 and MCF-7) to curcumin (2 and 20 µM) and observed a highly significant inhibitory effect on the expression of both PRMT5 and MEP50. The level of symmetrical dimethylarginine (SDMA) in multiple proteins, and more specifically, the H4R3me2s mark (which predominates in GC-rich motifs in nucleosomal DNA) was also diminished significantly. We also found that curcumin significantly reduced the level and enrichment of the transcription factors Sp1 and NF-YA which shares their binding sites within the GC-rich region of the PRMT5 proximal promoter. Furthermore, the involvement of both PKC-p38-ERK-cFos and AKT-mTOR signalling was observed in reducing the Sp1 and NF-YA expression by curcumin. Therefore, we propose curcumin decreased the expression of PRMT5 in these cells by affecting at least these two transcription factors. Altogether, we report a new molecular target of curcumin and further elucidation of this proposed mechanism through which curcumin affects the PRMT5-MEP50 methyltransferase expression might be explored for its therapeutic application.

Lead induces the up-regulation of the protein arginine methyltransferase 5 possibly by its promoter demethylation.

The studies on lead (Pb) exposure linking to epigenetic modulations are caused by its differential actions on global DNA methylation and histone modifications. These epigenetic changes may result in increased accessibility of the transcription factors to promoter DNA-binding elements leading to activation and expression of the gene. The protein arginine methyltransferase 5 (PRMT5) and its partner methylosome protein 50 (MEP50) together catalyze the mono- and symmetric dimethylation of arginine residues in many histone and non-histone protein substrates. Moreover, it is overexpressed in many forms of cancer. In the present study, the effects of Pb on the PRMT5 and MEP50 expression and formation of the symmetrically dimethylated arginine (SDMA), the catalytic product of the PRMT5-MEP50 complex were analyzed in vitro after exposing the A549 and MCF-7 cells. The results show that exposure to 0.1 and 1 µM of Pb strongly enhanced the expression of both PRMT5 and MEP50 transcript and protein leading to increased SDMA levels globally with H4R3 being increasingly symmetrically dimethylated in a dose-dependent manner after 48 h of Pb exposure in both cell types. The methylation-specific PCR also revealed that the CpG island present on the PRMT5 promoter proximal region was increasingly demethylated as the dose of Pb increased in a 48-h exposure window in both cells, with MCF-7 being more responsive to Pb-mediated PRMT5 promoter demethylation. The bisulfite sequencing confirmed this effect. The findings therefore indicate that Pb exposure increasing the PRMT5 expression might be one of the contributing epigenetic factors in the lead-mediated disease processes as PRMT5 has a versatile role in cellular functions and oncogenesis.

Expression of protein arginine methyltransferase-5 in oral squamous cell carcinoma and its significance in epithelial-to-mesenchymal transition.

Protein arginine methyltransferases (PRMT) 5, a member of type II arginine methyltransferases, catalyzes the symmetrical dimethylation of arginine residues on histone and non-histone substrates. Although the overexpression of PRMT5 has been reported in various cancers, its role in oral squamous cell carcinoma (OSCC) has not been elucidated. In the present study, we immunohistochemically examined the expression of PRMT5 in surgically resected oral epithelial dysplasia (OED, n = 8), oral intraepithelial neoplasia (OIN)/carcinoma in situ (CIS) (n = 11) and OSCC (n = 52) with or without contiguous OED lesions. In the normal epithelium, PRMT5 was weakly expressed in the cytoplasm of basal layer cells. In OED, OIN/CIS, and OSCC, its expression consistently and uniformly increased in the cytoplasm of dysplastic and cancer cells. Moreover, nuclear and cytoplasmic localization was detected in the invasive front of cancer cells, particularly in cases showing poor differentiation or aggressive invasion patterns. The concomitant nuclear and cytoplasmic expression of PRMT5 correlated with the loss of E-cadherin and cytokeratin 17, and the upregulation of vimentin, features that are both indicative of epithelial-to-mesenchymal transition. PRMT5 may play a role from early oncogenesis through to the progression of OSCC, particularly in the aggressive mode of stromal invasion.

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

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

Differential expression, distinct localization and opposite effect on Golgi structure and cell differentiation by a novel splice variant of human PRMT5.

Alternative splicing contributes greatly to the proteomic diversity of metazoans. Protein arginine methyltransferase 5 (PRMT5) methylates arginines of Golgi components and other factors exerting diverse effects on cell growth/differentiation, but the underlying molecular basis for its subcellular distribution and diverse roles has not been fully understood. Here we show the detailed properties of an evolutionarily emerged splice variant of human PRMT5 (PRMT5S) that is distinct from the original isoform (PRMT5L). The isoforms are differentially expressed among mammalian cells and tissues. The PRMT5S is distributed all over the cell but PRMT5L mainly colocalizes with Giantin, a Golgi marker. PRMT5 knockdown led to an enlarged Giantin pattern, which was prevented by the expression of either isoform. Rescuing PRMT5S also increased the percentage of cells with an interphase Giantin pattern compacted at one end of the nucleus, consistent with its cell cycle-arresting effect, while rescuing PRMT5L increased that of the mitotic Giantin patterns of dynamically fragmented structures. Moreover, the isoforms are differentially expressed during neuronal or dendritic cell differentiation, and their ectopic expression showed an opposite effect on dendritic cell differentiation. Furthermore, besides their differential regulation of gene expression, both isoforms also similarly regulate over a thousand genes particularly those involved in apoptosis and differentiation. Taking these properties together, we propose that their differential expression and subcellular localization contribute to spatial and temporal regulation of arginine methylation and gene expression to exert different effects. The novel PRMT5S likely contributes to the observed diverse effects of PRMT5 in cells.

Novel Protein Arginine Methyltransferase 8 Isoform Is Essential for Cell Proliferation.

Identification of molecular mechanisms that regulate cellular replicative lifespan is needed to better understand the transition between a normal and a neoplastic cell phenotype. We have previously reported that low oxygen-mediated activity of FGF2 leads to an increase in cellular lifespan and acquisition of regeneration competence in human dermal fibroblasts (iRC cells). Though cells display a more plastic developmental phenotype, they remain non-tumorigenic when injected into SCID mice (Page et al. [2009] Cloning Stem Cells 11:417-426; Page et al. [2011] Eng Part A 17:2629-2640) allowing for investigation of mechanisms that regulate increased cellular lifespan in a non-tumorigenic system. Analysis of chromatin modification enzymes by qRT-PCR revealed a 13.3-fold upregulation of the arginine methyltransferase PRMT8 in iRC cells. Increased protein expression was confirmed in both iRC and human embryonic stem cells-the first demonstration of endogenous human PRMT8 expression outside the brain. Furthermore, iRC cells express a novel PRMT8 mRNA variant. Using siRNA-mediated knockdown we demonstrated that this novel variant was required for proliferation of human dermal fibroblasts (hDFs) and grade IV glioblastomas. PRMT8 upregulation in a non-tumorigenic system may offer a potential diagnostic biomarker and a therapeutic target for cells in pre-cancerous and cancerous states. J. Cell. Biochem. 117: 2056-2066, 2016. © 2016 Wiley Periodicals, Inc.

The protein arginine methyltransferase PRMT5 regulates Aß-induced toxicity in human cells and Caenorhabditis elegans models of Alzheimer's disease.

The protein arginine methyltransferase 5 (PRMT5) controls cell growth and apoptosis by catalyzing mono and symmetric dimethylation of arginine residues. In human brain tissue, PRMT5 is predominantly expressed in neuronal cells. There is evidence that PRMT5 provides protection against cell death, but the impact of PRMT5 on neuronal apoptosis during the evolution of Alzheimer's disease has not been tested. In the present study, we show that PRMT5 is down-regulated by ß-amyloid (Aß) in primary neurons and SH-SY5Y cells, and this is associated with the up-regulation of the PRMT5 target protein E2F-1. Furthermore, knockdown of PRMT5 in SH-SY5Y cells over-expressing the Swedish mutant form of human amyloid-ß precursor protein caused activation of E2F-1/p53/Bax, NF-κB, and GSK-3ß pathways, which coincided with increased apoptosis. Co-depletion of E2F-1 reduced the activation of p53/Bax, NF-κB, and GSK-3ß, and limited cell apoptosis. In addition, inhibiting NF-κB and GSK-3ß activity by specific inhibitors also attenuated cell apoptosis, suggesting that E2F-1/NF-κB/GSK-3ß pathways mediate for apoptosis induced by PRMT5 depletion. More importantly, knockdown of PRMT5 resulted in more paralysis in a transgenic Caenorhabditis elegans strain CL2006, indicating that PRMT5 provides protection against Aß toxicity in vivo. Collectively, our findings identify PRMT5 as a novel regulator of Aß toxicity and suggest that strategies aimed at activating PRMT5 in the neuron may represent a potential therapeutic approach for the prevention of Alzheimer's disease. We propose the following cascade for protein arginine methyltransferase 5 (PRMT5)-mediated neuronal death: amyloid beta (Aß) deposition decreases PRMT5 expression in neurons, which increases E2F-1 expression - a PRMT5 target protein - and subsequently activates GSK-3ß and NF-κB to induce caspase-3-dependent neuronal apoptosis. These findings might provide a strategy for the treatment of Alzheimer's disease.

PRMT5 and the role of symmetrical dimethylarginine in chromatoid bodies of planarian stem cells.

Planarian flatworms contain a population of adult stem cells (neoblasts) that proliferate and generate cells of all tissues during growth, regeneration and tissue homeostasis. A characteristic feature of neoblasts is the presence of chromatoid bodies, large cytoplasmic ribonucleoprotein (RNP) granules morphologically similar to structures present in the germline of many organisms. This study aims to reveal the function, and identify additional components, of planarian chromatoid bodies. We uncover the presence of symmetrical dimethylarginine (sDMA) on chromatoid body components and identify the ortholog of protein arginine methyltransferase PRMT5 as the enzyme responsible for sDMA modification in these proteins. RNA interference-mediated depletion of planarian PRMT5 results in defects in homeostasis and regeneration, reduced animal size, reduced number of neoblasts, fewer chromatoid bodies and increased levels of transposon and repetitive-element transcripts. Our results suggest that PIWI family member SMEDWI-3 is one sDMA-containing chromatoid body protein for which methylation depends on PRMT5. Additionally, we discover an RNA localized to chromatoid bodies, germinal histone H4. Our results reveal new components of chromatoid bodies and their function in planarian stem cells, and also support emerging studies indicative of sDMA function in stabilization of RNP granules and the Piwi-interacting RNA pathway.

Proliferative role of TRAF4 in breast cancer by upregulating PRMT5 nuclear expression.

In this study, we examined protein arginine methyltransferase 5 (PRMT5) and tumor necrosis factor receptor-associated 4 (TRAF4) expression in breast cancer to find the interaction mechanism between the two. We examined TRAF4 and PRMT5 expression by immunohistochemistry and found that their expression is positively correlated in breast cancer. Besides, PRMT5 expression was significantly associated with histological type and tumor size (p < 0.05). PRMT5 nuclear expression was significantly associated with HER2 expression (p < 0.05). PRMT5 and TRAF4 were both overexpressed in breast cancer tissues and cells, and we found that PRMT5 binds to the zinc finger structures in TRAF4 by coimmunoprecipitation and Western blotting. We also tested the potential regulatory effect between TRAF4 and PRMT5. TRAF4 upregulated PRMT5 expression, which occurred predominantly in the nucleus, on which TRAF4 promotion of cell proliferation in breast cancer is mainly dependent. PRMT5 may play an important role in activation of the NF-κB signaling pathway.

Protein arginine methyltransferase 10 is required for androgen-dependent proliferation of LNCaP prostate cancer cells.

Androgen receptor (AR) signaling is the master regulator of prostate cell growth. Here, to better understand AR signaling, we searched for AR-interacting proteins by yeast two-hybrid screening and identified protein arginine methyltransferase 10 (PRMT10) as one of the interacting proteins. PRMT10 was highly expressed in reproductive tissues, such as prostate. Immunostaining showed that PRMT10 was expressed in the nucleus of both epithelia and stroma of rat prostate. In human prostate cancer LNCaP cells, PRMT10 co-immunoprecipitated with AR in both the presence and absence of dihydrotestosterone (DHT). Knockdown of PRMT10 by siRNA decreased DHT-dependent LNCaP cell growth and induction of prostate-specific antigen, an AR-target gene, without apparent loss of AR. DHT decreased PRMT10 at both the mRNA and protein levels. The decrease in PRMT10 was canceled by knockdown of AR or an AR antagonist. These results indicate that PRMT10 plays an important role in androgen-dependent proliferation of prostate cancer cells.

Glucagon-like peptide-1 receptor agonist inhibits asymmetric dimethylarginine generation in the kidney of streptozotocin-induced diabetic rats by blocking advanced glycation end product-induced protein arginine methyltranferase-1 expression.

Advanced glycation end products (AGEs) and their receptor (RAGE) play a role in diabetic nephropathy. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, contributes to diabetic nephropathy. We have found that glucagon-like peptide-1 (GLP-1) inhibits the AGE-induced inflammatory reactions in endothelial cells. However, effects of GLP-1 on the AGE-RAGE-ADMA axis are unknown. This study examined the effects of GLP-1 on reactive oxygen species (ROS) generation, gene expression of protein arginine methyltransfetase-1 (PRMT-1), an enzyme that mainly generates ADMA, and ADMA levels in human proximal tubular cells. Streptozotocin-induced diabetic rats received continuous i.p. infusion of 0.3 µg of vehicle or 1.5 µg of the GLP-1 analog exendin-4 per kilogram of body weight for 2 weeks. We further investigated whether and how exendin-4 treatment reduced ADMA levels and renal damage in streptozotocin-induced diabetic rats. GLP-1 inhibited the AGE-induced RAGE and PRMT-1 gene expression, ROS, and ADMA generation in tubular cells, which were blocked by small-interfering RNAs raised against GLP-1 receptor. Exendin-4 treatment decreased gene expression of Rage, Prmt-1, Icam-1, and Mcp-1 and ADMA level; reduced urinary excretions of 8-hydroxy-2'-deoxyguanosine and albumin; and improved histopathologic changes of the kidney in diabetic rats. Our present study suggests that GLP-1 receptor agonist may inhibit the AGE-RAGE-mediated ADMA generation by suppressing PRMT-1 expression via inhibition of ROS generation, thereby protecting against the development and progression of diabetic nephropathy.

Upregulated protein arginine methyltransferase 1 by IL-4 increases eotaxin-1 expression in airway epithelial cells and participates in antigen-induced pulmonary inflammation in rats.

Protein arginine methyltransferases (PRMTs), catalyzing methylation of both histones and other cellular proteins, have emerged as key regulators of various cellular processes. This study aimed to identify key PRMTs involved in Ag-induced pulmonary inflammation (AIPI), a rat model for asthma, and to explore the role of PRMT1 in the IL-4-induced eosinophil infiltration process. E3 rats were i.p. sensitized with OVA/alum and intranasally challenged with OVA to induce AIPI. The expressions of PRMT1-6, eotaxin-1, and CCR3 in lungs were screened by real-time quantitative PCR. Arginine methyltransferase inhibitor 1 (AMI-1, a pan-PRMT inhibitor) and small interfering RNA-PRMT1 were used to interrupt the function of PRMT1 in A549 cells. In addition, AMI-1 was administrated intranasally to AIPI rats to observe the effects on inflammatory parameters. The results showed that PRMT1 expression was mainly expressed in bronchus and alveolus epithelium and significantly upregulated in lungs from AIPI rats. The inhibition of PRMTs by AMI-1 and the knockdown of PRMT1 expression were able to downregulate the expressions of eotaxin-1 and CCR3 with the IL-4 stimulation in the epithelial cells. Furthermore, AMI-1 administration to AIPI rats can also ameliorate pulmonary inflammation, reduce IL-4 production and humoral immune response, and abrogate eosinophil infiltration into the lungs. In summary, PRMT1 expression is upregulated in AIPI rat lungs and can be stimulated by IL-4. Intervention of PRMT1 activity can abrogate IL-4-dependent eotaxin-1 production to influence the pulmonary inflammation with eosinophil infiltration. The findings may provide experimental evidence that PRMT1 plays an important role in asthma pathogenesis.

The antidepressant effects of protein arginine methyltransferase 2 involve neuroinflammation.

Protein arginine methyltransferase (PRMT) 2 catalyzes the methylation of arginine residues in histones. Depression is associated with histone methylation; however, more comprehensive research is needed on how PRMT2 regulates depression. The present study aimed to investigate the effects and possible mechanism(s) of PRMT2 overexpression on depression-like behavior induced by chronic unpredictable mild stress (CUMS) in rats, and whether lentivirus-mediated PRMT2 overexpression in the hippocampus suppresses depression-like behavior. Furthermore, the PRMT2 inhibitor MS023 was administered to the animals to investigate whether the antidepressant effect of PRMT2 overexpression could be reversed. Behavioral experiments were performed to detect depression-like behavior in rats. Western blotting was used to determine protein expression levels of PRMT2, histone H3R8 asymmetric dimethylation (H3R8me2a), inducible nitric oxide synthase (iNOS), and arginase 1 (Arg1) in rat hippocampal tissues. Hippocampal microglia and PRMT2 were stained using immunofluorescence techniques. Enzyme-linked immunosorbent assay was used to determine the levels of various inflammatory factors in rat hippocampal tissue. Results of analysis revealed that PRMT2 overexpression in the hippocampus exerted an antidepressant effect. PRMT2 overexpression in the hippocampus reduced the proportion of activated microglia in the hippocampus, upregulated Arg1 and H3R8me2a expression, and downregulated iNOS expression. PRMT2 overexpression in the hippocampus inhibited the release of pro-inflammatory factors and promoted the release of anti-inflammatory factors. In summary, PRMT2 overexpression in the hippocampus promoted the conversion of microglia from the M1 to M2 type, resulting in an antidepressant effect. These results suggest that PRMT2 may be a potential therapeutic target to prevent and treat depression.

S-adenosylmethionine-dependent protein methylation is required for expression of selenoprotein P and gluconeogenic enzymes in HepG2 human hepatocytes.

Cellular methylation processes enable expression of gluconeogenic enzymes and metabolism of the nutrient selenium. Selenium status has been proposed to relate to type II diabetes risk, and plasma levels of selenoprotein P (SEPP1) have been positively correlated with insulin resistance. Increased expression of gluconeogenic enzymes glucose-6-phosphatase (G6PC) and phosphoenolpyruvate carboxykinase 1 (PCK1) has negative consequences for blood glucose management in type II diabetics. Transcriptional regulation of SEPP1 is directed by the same transcription factors that control the expression of G6PC and PCK1, and these factors are activated by methylation of arginine residues. We sought to determine whether expression of SEPP1 and the aforementioned glucoconeogenic enzymes are regulated by protein methylation, the levels of which are reliant upon adequate S-adenosylmethionine (SAM) and inhibited by S-adenosylhomocysteine (SAH). We treated a human hepatocyte cell line, HepG2, with inhibitors of adenosylhomocysteine hydrolase (AHCY) known to increase concentration of SAH before analysis of G6PC, PCK1, and SEPP1 expression. Increasing SAH decreased 1) the SAM/SAH ratio, 2) protein-arginine methylation, and 3) expression of SEPP1, G6PC, and PCK1 transcripts. Furthermore, hormone-dependent induction of gluconeogenic enzymes was reduced by inhibition of protein methylation. When protein-arginine methyltransferase 1 expression was reduced by siRNA treatment, G6PC expression was inhibited. These findings demonstrate that hepatocellular SAM-dependent protein methylation is required for both SEPP1 and gluconeogenic enzyme expression and that inhibition of protein arginine methylation might provide a route to therapeutic interventions in type II diabetes.

Thyroid hormone activates protein arginine methyltransferase 1 expression by directly inducing c-Myc transcription during Xenopus intestinal stem cell development.

Adult organ-specific stem cells are essential for organ homeostasis and tissue repair and regeneration. The formation of such stem cells during vertebrate development is poorly understood. Intestinal remodeling during thyroid hormone (T3)-dependent Xenopus metamorphosis resembles postembryonic intestinal maturation in mammals. During metamorphosis, the intestine is remodeled de novo via a yet unknown mechanism. Protein arginine methyltransferase 1 (PRMT1) is up-regulated in and required for adult intestinal stem cells during metamorphosis. PRMT1 up-regulation is the earliest known molecular event for the developing stem cells and is also conserved during zebrafish and mouse intestinal development. To analyze how PRMT1 is specifically up-regulated during the formation of the adult intestinal stem cells, we cloned the Xenopus PRMT1 promoter and characterized it in CaCo-2 cells, a human cell line with intestinal stem cell characteristics. Through a series deletion and mutational analyses, we showed that the stem cell-associated transcription factor c-Myc could bind to a conserved site in the first intron to activate the promoter. Furthermore, we demonstrated that during metamorphosis, both c-Myc and PRMT1 were highly up-regulated, specifically in the remodeling intestine but not the resorbing tail, and that c-Myc was induced by T3 prior to PRMT1 up-regulation. In addition, we showed that T3 directly activated the c-Myc gene during metamorphosis in the intestine via binding of the T3 receptor to the c-Myc promoter. These results suggest that T3 induces c-Myc transcription directly in the intestine, that c-Myc, in turn, activates PRMT1 expression, and that this is an important gene regulation cascade controlling intestinal stem cell development.

Protein arginine methyltransferase 7 regulates cellular response to DNA damage by methylating promoter histones H2A and H4 of the polymerase δ catalytic subunit gene, POLD1.

Covalent modification of histones by protein arginine methyltransferases (PRMTs) impacts genome organization and gene expression. In this report, we show that PRMT7 interacts with the BRG1-based hSWI/SNF chromatin remodeling complex and specifically methylates histone H2A Arg-3 (H2AR3) and histone H4 Arg-3 (H4R3). To elucidate the biological function of PRMT7, we knocked down its expression in NIH 3T3 cells and analyzed global gene expression. Our findings show that PRMT7 negatively regulates expression of genes involved in DNA repair, including ALKBH5, APEX2, POLD1, and POLD2. Chromatin immunoprecipitation (ChIP) revealed that PRMT7 and dimethylated H2AR3 and H4R3 are enriched at target DNA repair genes in parental cells, whereas PRMT7 knockdown caused a significant decrease in PRMT7 recruitment and H2AR3/H4R3 methylation. Decreased PRMT7 expression also resulted in derepression of target DNA repair genes and enhanced cell resistance to DNA-damaging agents. Furthermore, we show that BRG1 co-localizes with PRMT7 on target promoters and that expression of a catalytically inactive form of BRG1 results in derepression of PRMT7 target DNA repair genes. Remarkably, reducing expression of individual PRMT7 target DNA repair genes showed that only the catalytic subunit of DNA polymerase, POLD1, was able to resensitize PRMT7 knock-down cells to DNA-damaging agents. These results provide evidence for the important role played by PRMT7 in epigenetic regulation of DNA repair genes and cellular response to DNA damage.