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.

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.

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.

Altered L-Arginine Metabolic Pathways in Gastric Cancer: Potential Therapeutic Targets and Biomarkers.

There is a pressing need for molecular targets and biomarkers in gastric cancer (GC). We aimed at identifying aberrations in L-arginine metabolism with therapeutic and diagnostic potential. Systemic metabolites were quantified using mass spectrometry in 293 individuals and enzymes' gene expression was quantified in 29 paired tumor-normal samples using qPCR and referred to cancer pathology and molecular landscape. Patients with cancer or benign disorders had reduced systemic arginine, citrulline, and ornithine and elevated symmetric dimethylarginine and dimethylamine. Citrulline and ornithine depletion was accentuated in metastasizing cancers. Metabolite diagnostic panel had 91% accuracy in detecting cancer and 70% accuracy in differentiating cancer from benign disorders. Gastric tumors had upregulated NOS2 and downregulated ASL, PRMT2, ORNT1, and DDAH1 expression. NOS2 upregulation was less and ASL downregulation was more pronounced in metastatic cancers. Tumor ASL and PRMT2 expression was inversely related to local advancement. Enzyme up- or downregulation was greater or significant solely in cardia subtype. Metabolic reprogramming in GC includes aberrant L-arginine metabolism, reflecting GC subtype and pathology, and is manifested by altered interplay of its intermediates and enzymes. Exploiting L-arginine metabolic pathways for diagnostic and therapeutic purposes is warranted. Functional studies on ASL, PRMT2, and ORNT1 in GC are needed.

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.

PRMT5 Promotes EMT Through Regulating Akt Activity in Human Lung Cancer.

The type II protein arginine methyltransferase 5 (PRMT5) has been engaged in various human cancer development and progression types. Nevertheless, few studies uncover the biological functions of PRMT5 in the epithelial-mesenchymal transition (EMT) of human lung cancer cells, and the associated molecular mechanisms and signaling cascades are entirely unknown. Here, we show that PRMT5 is the ectopic expression in human lung cancer tissues and cell lines. Further study reveals that silencing PRMT5 by lentivirus-mediated shRNA or blocking of PRMT5 by specific inhibitor GSK591 attenuates the expression levels of EMT-related markers in vivo, using the xenograft mouse model. Moreover, our results show that down-regulation of PRMT5 impairs EGFR/Akt signaling cascades in human lung cancer cells, whereas re-expression of PRMT5 recovers those changes, suggesting that PRMT5 regulates EMT probably through EGFR/Akt signaling axis. Altogether, our results demonstrate that PRMT5 serves as a critical oncogenic regulator and promotes EMT in human lung cancer cells. More importantly, our findings also suggest that PRMT5 may be a potential therapeutic candidate for the treatment of human lung cancer.

GCN sensitive protein translation in yeast.

Levels of protein translation by ribosomes are governed both by features of the translation machinery as well as sequence properties of the mRNAs themselves. We focus here on a striking three-nucleotide periodicity, characterized by overrepresentation of GCN codons and underrepresentation of G at the second position of codons, that is observed in Open Reading Frames (ORFs) of mRNAs. Our examination of mRNA sequences in Saccharomyces cerevisiae revealed that this periodicity is particularly pronounced in the initial codons-the ramp region-of ORFs of genes with high protein expression. It is also found in mRNA sequences immediately following non-standard AUG start sites, located upstream or downstream of the standard annotated start sites of genes. To explore the possible influences of the ramp GCN periodicity on translation efficiency, we tested edited ramps with accentuated or depressed periodicity in two test genes, SKN7 and HMT1. Greater conformance to (GCN)n was found to significantly depress translation, whereas disrupting conformance had neutral or positive effects on translation. Our recent Molecular Dynamics analysis of a subsystem of translocating ribosomes in yeast revealed an interaction surface that H-bonds to the +1 codon that is about to enter the ribosome decoding center A site. The surface, comprised of 16S/18S rRNA C1054 and A1196 (E. coli numbering) and R146 of ribosomal protein Rps3, preferentially interacts with GCN codons, and we hypothesize that modulation of this mRNA-ribosome interaction may underlie GCN-mediated regulation of protein translation. Integration of our expression studies with large-scale reporter studies of ramp sequence variants suggests a model in which the C1054-A1196-R146 (CAR) interaction surface can act as both an accelerator and braking system for ribosome translation.

PRMT7 promotes the growth of renal cell carcinoma through modulating the ß-catenin/C-MYC axis.

Arginine methylation is mainly catalyzed by protein arginine methyltransferases (PRMTs) and is one of the most common posttranslational modifications closely related to the development of cancer. PRMT7 is overexpressed in various tumors and promotes the malignant progression of tumors, but the expression and role of PRMT7 in renal cell carcinoma (RCC) remains unclear. Here, we report for the first time that the expression of PRMT7 is increased in clear cell renal cell carcinoma (ccRCC) tissues and that it may act as an independent predictor for the poor prognosis of ccRCC patients. We found that PRMT7 promotes RCC cell proliferation both in vitro and in vivo. Moreover, the methyltransferase inhibitor adenosine dialdehyde (Adox) blocks the action of PRMT7 in ccRCC cells. Furthermore, PRMT7 regulates the expression of C-MYC, which plays an important role in promoting ccRCC cell proliferation, and it accelerates the tumor development of RCC in a C-MYC-dependent manner. Mechanistically, PRMT7 upregulates the expression of C-MYC via methylating ß-catenin and inhibiting the ubiquitin-mediated degradation of ß-catenin. In conclusion, our study demonstrates that overexpressed PRMT7 in ccRCC cells acts as an oncogene to promote the growth of renal cell carcinoma through regulating the ß-catenin/C-MYC axis, thereby providing new strategies and targets for the treatment of ccRCC patients.

PRMT6 promotes endometrial cancer via AKT/mTOR signaling and indicates poor prognosis.

Arginine methylation plays essential roles in post-transcriptional modification and signal transduction. Dysregulation of protein arginine methyltransferases (PRMTs) has been reported in human cancers, yet the expression and biological function of PRMT6 in endometrial cancer (EMC) remains unclear. Here, we show that PRMT6 is upregulated in EMC and exhibits oncogenic activities via activation of AKT/mTOR pathway. The expression of PRMT6 in EMC is much higher than that in the adjacent nontumorous tissues. Elevated PRMT6 expression is significantly associated with higher histological tumor grade and unfavorable prognosis in two independent cohorts consisting of a total of 564 patients with EMC. In vitro data demonstrate that PRMT6 expression was identified as a downstream target of miR-372-3p. Ectopic expression of miR-372-3p downregulates PRMT6. Overexpression of PRMT6 promotes EMC cell proliferation and migration, whereas knockdown of PRMT6 leads to opposite phenotypes. Mechanistically, PRMT6 induces the phosphorylation of AKT and mTOR in EMC cells. Inhibition of AKT/mTOR signaling by MK2206 or rapamycin attenuates the PRMT6-mediated EMC progression. In clinical samples, high expression of PRMT6 was correlated to low expression of miR-372-3p and high expression of phosphorylated AKT. Collectively, our findings suggest PRMT6 may function as an oncogene to promote tumor progression, and be of prognostic value to predict disease-free survival of patients with EMC. The newly identified miR-372-3p/PRMT6/AKT/mTOR axis represents a new promising target for EMC management.

MiR-1266 suppresses the growth and metastasis of prostate cancer via targeting PRMT5.

OBJECTIVE: To elucidate the correlation between microRNA-1266 (miR-1266) and prostate cancer (PCa) progression, and to investigate the possible underlying mechanism. PATIENTS AND METHODS: The expression level of miR-1266 and protein arginine methyltransferase 5 (PRMT5) in PCa tissues and cell lines was first detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). After up-regulating or down-regulating miR-1266 expression in cells, cell proliferation, migration and invasion abilities were detected. Possible target genes of miR-1266 were predicted and validated by bioinformatics analysis and dual-luciferase reporter gene assay, respectively. Finally, abnormal expression of PRMT5 was ascertained after transfection. RESULTS: MiR-1266 was lowly expressed in PCa tissues and cell lines, whereas PRMT5 exhibited the opposite results. Up-regulated expression of miR-1266 significantly inhibited the proliferation, migration and invasion abilities of PC-3 cells. However, the growth and migration of DU145 cells with low miR-1266 expression were significantly accelerated. Meanwhile, the number of invading cells was significantly increased. PRMT5 was verified as a potential target gene of miR-1266. Furthermore, results found that miR-1266 was negatively correlated with PRMT5. In addition, the expression of PRMT5 was remarkably decreased after miR-1266 overexpression, which could be restored after knockdown of miR-1266. CONCLUSIONS: MiR-1266 inhibits the growth and metastasis of PCa by targeting PRMT5. We may provide a potential and prospective therapeutic target for PCa.

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.

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.

Nephroprotective effects of nebivolol in 2K1C rats through regulation of the kidney ROS-ADMA-NO pathway.

BACKGROUND: To evaluate the protective effect of nebivolol against kidney damage and elucidate the underlying mechanism in a two-kidney, one-clip (2K1C) rat model. METHODS: 2K1C rats were obtained by clipping left renal artery of male Wistar rats and were considered hypertensive when systolic blood pressure (SBP) was ≥160mmHg 4 weeks after surgery. The 2K1C hypertensive rats were divided into untreated, nebivolol (10mg/kg, ig), and atenolol (80mg/kg, ig) treatment groups. The treatments lasted for 8 weeks. SBP, kidney structure and function, plasma and kidney angiotensin (Ang) II, nitric oxide (NO), asymmetric dimethylarginine (ADMA), and the oxidant status were examined. Kidney protein expression of NADPH oxidase (Nox) isoforms and its subunit p22phox, nitric oxide synthase (NOS) isoforms, protein arginine N-methyltransferase (PRMT) 1, and dimethylarginine dimethylaminohydrolase (DDAH) 1 and 2 was tested by western blotting. RESULTS: Nebivolol and atenolol exerted similar hypotensive effects. However, atenolol had little effect while nebivolol significantly ameliorated the functional decline and structural damage in the kidney, especially in non-clipped kidney (NCK), which was associated with the reduction of Ang II in NCK. Moreover, nebivolol inhibited the NCK production of reactive oxygen species (ROS) by decreasing Nox2, Nox4, and p22phox expression. Further, nebivolol reduced the plasma and kidney ADMA levels by increasing DDAH2 expression and decreasing PRMT1 expression. Nebivolol also increased the NCK NO level by ameliorating the expression of kidney NOS isoforms. CONCLUSIONS: Our results demonstrated that long-term treatment with nebivolol had renoprotective effect in 2K1C rats partly via regulation of kidney ROS-ADMA-NO pathway.

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.

The tumor suppressive miR-26a regulation of FBXO11 inhibits proliferation, migration and invasion of hepatocellular carcinoma cells.

Accumulating researches identify microRNA-26a (miR-26a) as a tumor suppressor in hepatocellular carcinoma (HCC). F-box protein 11 (FBXO11), a predicted target gene of miR-26a, is an E3 ubiquitin ligase and a type II methyltransferase, and functions as a key regulator of tumor initiation and progression. This study was aimed to investigate the regulatory role of miR-26a in FBXO11 expression and explored the clinical significance as well as functional role of FBXO11 in HCC. The expression levels of miR-26a were prominently downregulated in HCC tissues compared to matched tumor-adjacent tissues. MiR-26a inversely regulated FBXO11 abundance in HCC cells. Hereby, miR-26a could directly target 3'UTR of FBXO11 mRNA to suppress its expression. Gene Expression Omnibus (GEO) database (GSE54236 and GSE45436) and our data demonstrated that the expression of FBXO11 was up-regulated in HCC tissues. The level of FBXO11 mRNA was inversely correlated with miR-26a expression in HCC specimens. High FBXO11 expression was positively correlated with large tumor size, venous infiltration and advanced tumor stage of HCC patients. Clinical prognostic analysis illustrated that high FBXO11 expression predicted a poor survival of HCC patients. In vitro, FBXO11 knockdown inhibited cell proliferation, colony formation, migration and invasion of HCC cells. Additionally, miR-26a overexpression showed a consistent effect with FBXO11 knockdown on these malignant behaviors of HCC cells. Notably, FBXO11 restoration reversed the inhibitory effect of miR-26a on HCC cell proliferation, colony formation, migration and invasion. In summary, these results indicated that miR-26a regulation of FBXO11 exhibited an oncogenic role in HCC. Inhibition of FBXO11 might serve as a therapeutic target for HCC.

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.

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.

PDGF-BB induces PRMT1 expression through ERK1/2 dependent STAT1 activation and regulates remodeling in primary human lung fibroblasts.

Tissue remodeling of sub-epithelial mesenchymal cells is a major pathology occurring in chronic obstructive pulmonary disease (COPD) and asthma. Fibroblasts, as a major source of interstitial connective tissue extracellular matrix, contribute to the fibrotic and inflammatory changes in these airways diseases. Previously, we described that protein arginine methyltransferase-1 (PRMT1) participates in airway remodeling in a rat model of pulmonary inflammation. In this study we investigated the mechanism by which PDGF-BB regulates PRMT1 in primary lung fibroblasts, isolated from human lung biopsies. Fibroblasts were stimulated with PDGF-BB for up-to 48h and the regulatory and activation of signaling pathways controlling PRMT1 expression were determined. PRMT1 was localized by immuno-histochemistry in human lung tissue sections and by immunofluorescence in isolated fibroblasts. PRMT1 activity was suppressed by the pan-PRMT inhibitor AMI1. ERK1/2 mitogen activated protein kinase (MAPK) was blocked by PD98059, p38 MAPK by SB203580, and STAT1 by small interference (si) RNA treatment. The results showed that PDGF-BB significantly increased PRMT1 expression after 1h lasting over 48h, through ERK1/2 MAPK and STAT1 signaling. The inhibition of ERK1/2 MAPK or of PRMT1 activity decreased PDGF-BB induced fibroblast proliferation, COX2 production, collagen-1A1 secretion, and fibronectin production. These findings suggest that PRMT1 is a central regulator of tissue remodeling and that the signaling sequence controlling its expression in primary human lung fibroblast is PDGF-ERK-STAT1. Therefore, PRMT1 presents a novel therapeutic and diagnostic target for the control of airway wall remodeling in chronic lung diseases.