PRMT6-mediated ADMA promotes p62 phase separation to form a negative feedback loop in ferroptosis.

Purpose: Due to intrinsic defensive response, ferroptosis-activating targeted therapy fails to achieve satisfactory clinical benefits. Though p62-Keap1-Nrf2 axis is activated to form a negative feedback loop during ferroptosis induction, how p62 is activated remains largely unknown. Methods: MTS assay was applied to measure cell growth. Lipid ROS was detected with C11-BODIPY reagent by flow cytometer. Quantitative real-time PCR (qPCR) and western blotting were performed to determine mRNA and protein level. Immunofluorescence (IF) was performed to examine the distribution of proteins. Fluorescence recovery after photobleaching (FRAP) was adopted to evaluate p62 phase separation. Immunoprecipitation (IP), co-IP and Proximal ligation assay (PLA) were performed to detected protein posttranslational modifications and protein-protein interactions. Tumor xenograft model was employed to inspect in vivo growth of pancreatic cancer cells. Results: Upon ferroptosis induction, Nuclear Factor E2 Related Factor 2 (Nrf2) protein and its downstream genes such as HMOX1 and NQO1 were upregulated. Knockdown of p62 significantly reversed Nrf2 upregulation and Keap1 decrease after ferroptosis induction. Knockdown of either p62 or Nrf2 remarkably sensitized ferroptosis induction. Due to augmented p62 phase separation, formation of p62 bodies were increased to recruit Keap1 after ferroptosis induction. Protein arginine methyltransferase 6 (PRMT6) mediated asymmetric dimethylarginine (ADMA) of p62 to increase its oligomerization, promoting p62 phase separation and p62 body formation. Knockdown of p62 or PRMT6 notably sensitized pancreatic cancer cells to ferroptosis both in vitro and in vivo through suppressing Nrf2 signaling. Conclusion: During ferroptosis induction, PRMT6 mediated p62 ADMA to promote its phase separation, sequestering Keap1 to activate Nrf2 signaling and inhibit ferroptosis. Therefore, targeting PRMT6-mediated p62 ADMA could be a new option to sensitize ferroptosis for cancer treatment.

Regulation of hepatic lipogenesis by asymmetric arginine methylation.

BACKGROUND AND AIMS: Hepatic lipogenesis is elevated in nutrient abundant conditions to convert the excess carbohydrate into triacylglycerol (TAG). Fatty acyl moiety of TAG is eventually transported into adipose tissues by very low density lipoprotein, leading to the accumulation of TAG as a preferred storage form of excess energy. Disruption of the balance between TAG clearance and synthesis leads to the accumulation of lipids in the liver, leading to the progression of non-alcoholic fatty liver disease (NAFLD) including non-alcoholic steatohepatitis. Protein arginine methyltransferase (PRMT) 6 has been linked to the various metabolic processes including hepatic gluconeogenesis, muscle atrophy and lipodystrophy in mouse models. However, the role of PRMT6 in the control of hepatic lipogenesis has not been elucidated to date. METHODS: We assessed the interaction between PRMT6 and LXR alpha by using co-immunoprecipitation assay. The specific arginine residue of LXR alpha that is methylated by PRMT6 was assessed by LC-MS/MS assay and the functional consequences of LXR alpha methylation was explored by mSREBP-1c luciferase assay. The effect of PRMT6 on hepatic lipogenesis was assessed by adenovirus-mediated ectopic expression of PRMT6 or knockdown of PRMT6 via shRNA in hepatocytes. Finally, the role of PRMT6 in hepatic lipid metabolism in vivo was explored by either ectopic expression of LXR alpha mutant that is defective in PRMT6-mediated arginine methylation or knockdown of PRMT6 in liver. RESULTS: We found that promoter activity of sterol regulatory element binding protein (SREBP) 1c is robustly activated by PRMT6. Interestingly, we demonstrated that PRMT6 binds to LXR alpha, a transcription factor for SREBP-1c, via its LXXLL motif, leading to the asymmetric dimethylation of an arginine residue and activation of this protein. Indeed, ectopic expression of PRMT6 in hepatocytes led to the enhanced expression of LXR alpha target genes in the lipogenic pathway. Conversely, genetic or pharmacological inhibition of PRMT6 diminished expression of lipogenic genes and the lipid accumulation in primary hepatocytes. Mechanistically, we found that asymmetric dimethylation of LXR alpha led to the dissociation of small heterodimer partner (SHP), a transcriptional co-inhibitor of this factor, resulting in the activation of LXR alpha-mediated transcriptional process. Finally, we showed that disruption of asymmetric dimethylation of LXR alpha in the liver led to the diminished expression of genes in the lipogenesis, resulting in the reduced hepatic lipid accumulation in high fat diet-fed mice in vivo. CONCLUSIONS: We showed that PRMT6 modulates LXR alpha activity by conferring asymmetric dimethylation of arginine 253, thus blocking SHP-mediated inhibition and promoting hepatic lipid accumulation. These results suggest that PRMT6 is critical in the control of lipid homeostasis by regulation of LXR alpha-mediated lipogenesis in the liver.

Discovery of a first-in-class degrader for the protein arginine methyltransferase 6 (PRMT6).

PRMT6 is a member of the protein arginine methyltransferase family, which participates in a variety of physical processes and plays an important role in the occurrence and development of tumors. Using small molecules to design and synthesize targeted protein degraders is a new strategy for drug development. Here, we report the first-in-class degrader SKLB-0124 for PRMT6 based on the hydrophobic tagging (HyT) method.Importantly, SKLB-0124 induced proteasome dependent degradation of PRMT6 and significantly inhibited the proliferation of HCC827 and MDA-MB-435 cells. Moreover, SKLB-0124 effectively induced apoptosis and cell cycle arrest in these two cell lines. Our data clarified that SKLB-0124 is a promising selective PRMT6 degrader for cancer therapy which is worthy of further evaluation.

PRMT6-mediated transcriptional activation of ythdf2 promotes glioblastoma migration, invasion, and emt via the wnt-ß-catenin pathway.

BACKGROUND: Protein arginine methyltransferase 6 (PRMT6) plays a crucial role in various pathophysiological processes and diseases. Glioblastoma (GBM; WHO Grade 4 glioma) is the most common and lethal primary brain tumor in adults, with a prognosis that is extremely poor, despite being less common than other systemic malignancies. Our current research finds PRMT6 upregulated in GBM, enhancing tumor malignancy. Yet, the specifics of PRMT6's regulatory processes and potential molecular mechanisms in GBM remain largely unexplored. METHODS: PRMT6's expression and prognostic significance in GBM were assessed using glioma public databases, immunohistochemistry (IHC), and immunoblotting. Scratch and Transwell assays examined GBM cell migration and invasion. Immunoblotting evaluated the expression of epithelial-mesenchymal transition (EMT) and Wnt-ß-catenin pathway-related proteins. Dual-luciferase reporter assays and ChIP-qPCR assessed the regulatory relationship between PRMT6 and YTHDF2. An in situ tumor model in nude mice evaluated in vivo conditions. RESULTS: Bioinformatics analysis indicates high expression of PRMT6 and YTHDF2 in GBM, correlating with poor prognosis. Functional experiments show PRMT6 and YTHDF2 promote GBM migration, invasion, and EMT. Mechanistic experiments reveal PRMT6 and CDK9 co-regulate YTHDF2 expression. YTHDF2 binds and promotes the degradation of negative regulators APC and GSK3ß mRNA of the Wnt-ß-catenin pathway, activating it and consequently enhancing GBM malignancy. CONCLUSIONS: Our results demonstrate the PRMT6-YTHDF2-Wnt-ß-Catenin axis promotes GBM migration, invasion, and EMT in vitro and in vivo, potentially serving as a therapeutic target for GBM.

Arginine methylation of ALKBH5 by PRMT6 promotes breast tumorigenesis via LDHA-mediated glycolysis.

ALKBH5 is a master regulator of N6-methyladenosine (m6A) modification, which plays a crucial role in many biological processes. Here, we show that ALKBH5 is required for breast tumor growth. Interestingly, PRMT6 directly methylates ALKBH5 at R283, which subsequently promotes breast tumor growth. Furthermore, arginine methylation of ALKBH5 by PRMT6 increases LDHA RNA stability via m6A demethylation, leading to increased aerobic glycolysis. Moreover, PRMT6-mediated ALKBH5 arginine methylation is confirmed in PRMT6-knockout mice. Collectively, these findings identify a PRMT6-ALKBH5-LDHA signaling axis as a novel target for the treatment of breast cancer.

Inhibition of protein arginine methyltransferase 6 activates interferon signaling and induces the apoptosis of endometrial cancer cells via histone modification.

Histone modification, a major epigenetic mechanism regulating gene expression through chromatin remodeling, introduces dynamic changes in chromatin architecture. Protein arginine methyltransferase 6 (PRMT6) is overexpressed in various types of cancer, including prostate, lung and endometrial cancer (EC). Epigenome regulates the expression of endogenous retrovirus (ERV), which activates interferon signaling related to cancer. The antitumor effects of PRMT6 inhibition and the role of PRMT6 in EC were investigated, using epigenome multi­omics analysis, including an assay for chromatin immunoprecipitation sequencing (ChIP­seq) and RNA sequencing (RNA­seq). The expression of PRMT6 in EC was analyzed using reverse transcription­quantitative polymerase chain reaction (RT­qPCR) and immunohistochemistry (IHC). The prognostic impact of PRMT6 expression was evaluated using IHC. The effects of PRMT6­knockdown (KD) were investigated using cell viability and apoptosis assays, as well as its effects on the epigenome, using ChIP­seq of H3K27ac antibodies and RNA­seq. Finally, the downstream targets identified by multi­omics analysis were evaluated. PRMT6 was overexpressed in EC and associated with a poor prognosis. PRMT6­KD induced histone hypomethylation, while suppressing cell growth and apoptosis. ChIP­seq revealed that PRMT6 regulated genomic regions related to interferons and apoptosis through histone modifications. The RNA­seq data demonstrated altered interferon­related pathways and increased expression of tumor suppressor genes, including NK6 homeobox 1 and phosphoinositide­3­kinase regulatory subunit 1, following PRMT6­KD. RT­qPCR revealed that eight ERV genes which activated interferon signaling were upregulated by PRMT6­KD. The data of the present study suggested that PRMT6 inhibition induced apoptosis through interferon signaling activated by ERV. PRMT6 regulated tumor suppressor genes and may be a novel therapeutic target, to the best of our knowledge, in EC.

PRMT6 deficiency or inhibition alleviates neuropathic pain by decreasing glycolysis and inflammation in microglia.

Microglia induced chronic inflammation is the critical pathology of Neuropathic pain (NP). Metabolic reprogramming of macrophage has been intensively reported in various chronic inflammation diseases. However, the metabolic reprogramming of microglia in chronic pain remains to be elusive. Here, we reported that immuno-metabolic markers (HIF-1α, PKM2, GLUT1 and lactate) were related with increased expression of PRMT6 in the ipsilateral spinal cord dorsal horn of the chronic construction injury (CCI) mice. PRMT6 deficiency or prophylactic and therapeutic intrathecal administration of PRMT6 inhibitor (EPZ020411) ameliorated CCI-induced NP, inflammation and glycolysis in the ipsilateral spinal cord dorsal horn. PRMT6 knockout or knockdown inhibited LPS-induced inflammation, proliferation and glycolysis in microglia cells. While PRMT6 overexpression exacerbated LPS-induced inflammation, proliferation and glycolysis in BV2 cells. Recent research revealed that PRMT6 could interact with and methylate HIF-1α, which increased HIF-1α protein stability. In sum, increased expression of PRMT6 exacerbates NP progress by increasing glycolysis and neuroinflammation through interacting with and stabilizing HIF-1α in a methyltransferase manner, which outlines novel pathological mechanism and drug target for NP.

HSV-1 reactivation results in post-herpetic neuralgia by upregulating Prmt6 and inhibiting cGAS-STING.

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

Chimeric PRMT6 protein produced by an endogenous retrovirus promoter regulates cell fate decision in mouse preimplantation embryos†.

Murine endogenous retrovirus with leucine tRNA primer, also known as MERVL, is expressed during zygotic genome activation in mammalian embryos. Here we show that protein arginine N-methyltransferase 6 (Prmt6) forms a chimeric transcript with MT2B2, one of the long terminal repeat sequences of murine endogenous retrovirus with leucine tRNA primer, and is translated into an elongated chimeric protein (PRMT6MT2B2) whose function differs from that of the canonical PRMT6 protein (PRMT6CAN) in mouse preimplantation embryos. Overexpression of PRMT6CAN in fibroblast cells increased asymmetric dimethylation of the third arginine residue of both histone H2A (H2AR3me2a) and histone H4 (H4R3me2a), while overexpression of PRMT6MT2B2 increased only H2AR3me2a. In addition, overexpression of PRMT6MT2B2 in one blastomere of mouse two-cell embryos promoted cell proliferation and differentiation of the blastomere into epiblast cells at the blastocyst stage, while overexpression of PRMT6CAN repressed cell proliferation. This is the first report of the translation of a chimeric protein (PRMT6MT2B2) in mouse preimplantation embryos. Our results suggest that analyzing chimeric transcripts with murine endogenous retrovirus with leucine tRNA primer will provide insight into the relationship between zygotic genome activation and subsequent intra- and extra-cellular lineage determination.

Machine Learning for Digital Scoring of PRMT6 in Immunohistochemical Labeled Lung Cancer.

Lung cancer is the leading cause of cancer death in the U.S. Therefore, it is imperative to identify novel biomarkers for the early detection and progression of lung cancer. PRMT6 is associated with poor lung cancer prognosis. However, analyzing PRMT6 expression manually in large samples is time-consuming posing a significant limitation for processing this biomarker. To overcome this issue, we trained and validated an automated method for scoring PRMT6 in lung cancer tissues, which can then be used as the standard method in future larger cohorts to explore population-level associations between PRMT6 expression and sociodemographic/clinicopathologic characteristics. We evaluated the ability of a trained artificial intelligence (AI) algorithm to reproduce the PRMT6 immunoreactive scores obtained by pathologists. Our findings showed that tissue segmentation to cancer vs. non-cancer tissues was the most critical parameter, which required training and adjustment of the algorithm to prevent scoring non-cancer tissues or ignoring relevant cancer cells. The trained algorithm showed a high concordance with pathologists with a correlation coefficient of 0.88. The inter-rater agreement was significant, with an intraclass correlation of 0.95 and a scale reliability coefficient of 0.96. In conclusion, we successfully optimized a machine learning algorithm for scoring PRMT6 expression in lung cancer that matches the degree of accuracy of scoring by pathologists.

Asymmetric dimethylation of AMPKα1 by PRMT6 contributes to the formation of phase-separated puncta.

AMP-activated protein kinase (AMPK) is a heterotrimeric serine/threonine kinase comprising α, ß, and γ subunits. AMPK is involved in intracellular energy metabolism and functions as a switch that turns various biological pathways in eukaryotes on and off. Several post-translational modifications regulating AMPK function have been demonstrated, including phosphorylation, acetylation, and ubiquitination; however, arginine methylation has not been reported in AMPKα1. We investigated whether arginine methylation occurs in AMPKα1. Screening experiments revealed arginine methylation of AMPKα1 mediated by protein arginine methyltransferase 6 (PRMT6). In vitro methylation and co-immunoprecipitation assays indicated that PRMT6 can directly interact with and methylate AMPKα1 without involvement of other intracellular components. In vitro methylation assays with truncated and point mutants of AMPKα1 revealed that Arg403 is the residue methylated by PRMT6. Immunocytochemical studies showed that the number of AMPKα1 puncta was enhanced in saponin-permeabilized cells when AMPKα1 was co-expressed with PRMT6, suggesting that PRMT6-mediated methylation of AMPKα1 at Arg403 alters the physiological characteristics of AMPKα1 and may lead to liquid-liquid phase separation.

The PRMT6/PARP1/CRL4B Complex Regulates the Circadian Clock and Promotes Breast Tumorigenesis.

Circadian rhythms, as physiological systems with self-regulatory functions in living organisms, are controlled by core clock genes and are involved in tumor development. The protein arginine methyltransferase 6 (PRMT6) serves as an oncogene in a myriad of solid tumors, including breast cancer. Hence, the primary aim of the current study is to investigate the molecular mechanisms by which the PRMT6 complex promotes breast cancer progression. The results show that PRMT6, poly(ADP-ribose) polymerase 1 (PARP1), and the cullin 4 B (CUL4B)-Ring E3 ligase (CRL4B) complex interact to form a transcription-repressive complex that co-occupies the core clock gene PER3 promoter. Moreover, genome-wide analysis of PRMT6/PARP1/CUL4B targets identifies a cohort of genes that is principally involved in circadian rhythms. This transcriptional-repression complex promotes the proliferation and metastasis of breast cancer by interfering with circadian rhythm oscillation. Meanwhile, the PARP1 inhibitor Olaparib enhances clock gene expression, thus, reducing breast carcinogenesis, indicating that PARP1 inhibitors have potential antitumor effects in high-PRMT6 expression breast cancer.

PRMT6 promotes tumorigenicity and cisplatin response of lung cancer through triggering 6PGD/ENO1 mediated cell metabolism.

Metabolic reprogramming is a hallmark of cancer, including lung cancer. However, the exact underlying mechanism and therapeutic potential are largely unknown. Here we report that protein arginine methyltransferase 6 (PRMT6) is highly expressed in lung cancer and is required for cell metabolism, tumorigenicity, and cisplatin response of lung cancer. PRMT6 regulated the oxidative pentose phosphate pathway (PPP) flux and glycolysis pathway in human lung cancer by increasing the activity of 6-phospho-gluconate dehydrogenase (6PGD) and α-enolase (ENO1). Furthermore, PRMT6 methylated R324 of 6PGD to enhancing its activity; while methylation at R9 and R372 of ENO1 promotes formation of active ENO1 dimers and 2-phosphoglycerate (2-PG) binding to ENO1, respectively. Lastly, targeting PRMT6 blocked the oxidative PPP flux, glycolysis pathway, and tumor growth, as well as enhanced the anti-tumor effects of cisplatin in lung cancer. Together, this study demonstrates that PRMT6 acts as a post-translational modification (PTM) regulator of glucose metabolism, which leads to the pathogenesis of lung cancer. It was proven that the PRMT6-6PGD/ENO1 regulatory axis is an important determinant of carcinogenesis and may become a promising cancer therapeutic strategy.

Decoding m6A RNA methylome identifies PRMT6-regulated lipid transport promoting AML stem cell maintenance.

N6-methyladenosine (m6A) is a common chemical modification for mammalian mRNA and exhibits high dynamics in various biological processes. However, dynamics of m6A RNA methylome during leukemogenesis remains unknown. Here, we delineate a comprehensive m6A landscape during acute myeloid leukemia (AML) development and identify PRMT6 as a key for maintaining AML stem cells. We observe an obvious change in m6A methylome during leukemogenesis and find that protein arginine methyltransferase PRMT6 and m6A reader IGF2BP2 maintain the function of human and murine leukemia stem cells (LSCs). Genetic deletion or pharmacological inhibition of PRMT6 damages AML development and LSC function. Mechanistically, IGF2BP2 stabilizes PRMT6 mRNA via m6A-mediated manner, which catalyzes H3R2me2a and suppresses lipid transporter MFSD2A expression. PRMT6 loss upregulates MFSD2A expression that increases docosahexaenoic acid levels and impairs LSC maintenance. Collectively, our findings reveal a critical role of PRMT6-MFSD2A signaling axis in AML development and provide a therapeutic strategy for targeting LSCs.

Design, synthesis and evaluation of antitumor activity of selective PRMT6 inhibitors.

PRMT6 is a member of the protein arginine methyltransferase family, which is involved in a variety of physiological processes and plays an important role in the occurrence and development of tumors. Due to the high homology of type Ⅰ PRMTs and the two close binding sites of the SAM pocket and the substrate pocket, selective PRMT6 inhibitors have rarely been reported. In this study, a series of (5-phenylpyridin-3-yl)methanamine derivatives were designed and synthesized, which could form hydrogen bonding interactions with the unique Glu49 of PRMT6, thereby improving the selectivity of the compounds for PRMT6. Among them, a25 had the best activity and selectivity, with more than 25-fold selectivity for PRMT1/8 and more than 50-fold selectivity for PRMT3/4/5/7, which was superior to these reported SAM competitive and substrate competitive PRMT6 inhibitors. Importantly, a25 could significantly inhibit the proliferation of various tumor cells and effectively induce apoptosis of cancer cells. Our data clarified that a25 is a promising selective PRMT6 inhibitor for cancer therapy which is worthy of further evaluation.

PRMT6 functionally associates with PRMT5 to promote colorectal cancer progression through epigenetically repressing the expression of CDKN2B and CCNG1.

BACKGROUND: Protein arginine methyltransferase 6 (PRMT6) is a type I arginine methyltransferase that asymmetrically dimethylates histone H3 arginine 2 (H3R2me2a). However, the biological roles and underlying molecular mechanisms of PRMT6 in colorectal cancer (CRC) remain unclear. METHODS: PRMT6 expression in CRC tissue was examined using immunohistochemistry. The effect of PRMT6 on CRC cells was investigated in vitro and in vivo. Mass spectrometry, co-immunoprecipitation and GST pulldown assays were performed to identify interaction partners of PRMT6. RNA-seq, chromatin immunoprecipitation, Western blot and qRT-PCR assays were used to investigate the mechanism of PRMT6 in gene regulation. RESULTS: PRMT6 is significantly upregulated in CRC tissues and facilitates cell proliferation of CRC cells in vitro and in vivo. Through RNA-seq analysis, CDKN2B (p15INK4b) and CCNG1 were identified as new transcriptional targets of PRMT6. PRMT6-dependent H3R2me2a mark was predominantly deposited at the promoters of CDKN2B and CCNG1 in CRC cells. Furthermore, PRMT5 was firstly characterized as an interaction partner of PRMT6. Notably, H3R2me2a coincides with PRMT5-mediated H4R3me2s and H3R8me2s marks at the promoters of CDKN2B and CCNG1 genes, thus leading to transcriptional repression of these genes. CONCLUSIONS: PRMT6 functionally associates with PRMT5 to promote CRC progression through epigenetically repressing the expression of CDKN2B and CCNG1. These insights raise the possibility that combinational intervention of PRMT6 and PRMT5 may be a promising strategy for CRC therapy.

Arginine Methylation of Integrin Alpha-4 Prevents Fibrosis Development in Alcohol-Associated Liver Disease.

BACKGROUND & AIMS: Alcohol-associated liver disease (ALD) comprises a spectrum of disorders including steatosis, steatohepatitis, fibrosis, and cirrhosis. We aimed to study the role of protein arginine methyltransferase 6 (PRMT6), a new regulator of liver function, in ALD progression. METHODS: Prmt6-deficient mice and wild-type littermates were fed Western diet with alcohol in the drinking water for 16 weeks. Mice fed standard chow diet or Western diet alone were used as a control. RESULTS: We found that PRMT6 expression in the liver is down-regulated in 2 models of ALD and negatively correlates with disease severity in mice and human liver specimens. Prmt6-deficient mice spontaneously developed liver fibrosis after 1 year and more advanced fibrosis after high-fat diet feeding or thioacetamide treatment. In the presence of alcohol Prmt6 deficiency resulted in a dramatic increase in fibrosis development but did not affect lipid accumulation or liver injury. In the liver PRMT6 is primarily expressed in macrophages and endothelial cells. Transient replacement of knockout macrophages with wild-type macrophages in Prmt6 knockout mice reduced profibrotic signaling and prevented fibrosis progression. We found that PRMT6 decreases profibrotic signaling in liver macrophages via methylation of integrin α-4 at R464 residue. Integrin α-4 is predominantly expressed in infiltrating monocyte derived macrophages. Blocking monocyte infiltration into the liver with CCR2 inhibitor reduced fibrosis development in knockout mice and abolished differences between genotypes. CONCLUSIONS: Taken together, our data suggest that alcohol-mediated loss of Prmt6 contributes to alcohol-associated fibrosis development through reduced integrin methylation and increased profibrotic signaling in macrophages.

PRMT6 promotes tumorigenicity and cisplatin response of lung cancer through triggering 6PGD/ENO1 mediated cell metabolism

Metabolic reprogramming is a hallmark of cancer, including lung cancer. However, the exact underlying mechanism and therapeutic potential are largely unknown. Here we report that protein arginine methyltransferase 6 (PRMT6) is highly expressed in lung cancer and is required for cell metabolism, tumorigenicity, and cisplatin response of lung cancer. PRMT6 regulated the oxidative pentose phosphate pathway (PPP) flux and glycolysis pathway in human lung cancer by increasing the activity of 6-phospho-gluconate dehydrogenase (6PGD) and α-enolase (ENO1). Furthermore, PRMT6 methylated R324 of 6PGD to enhancing its activity; while methylation at R9 and R372 of ENO1 promotes formation of active ENO1 dimers and 2-phosphoglycerate (2-PG) binding to ENO1, respectively. Lastly, targeting PRMT6 blocked the oxidative PPP flux, glycolysis pathway, and tumor growth, as well as enhanced the anti-tumor effects of cisplatin in lung cancer. Together, this study demonstrates that PRMT6 acts as a post-translational modification (PTM) regulator of glucose metabolism, which leads to the pathogenesis of lung cancer. It was proven that the PRMT6-6PGD/ENO1 regulatory axis is an important determinant of carcinogenesis and may become a promising cancer therapeutic strategy.

PRMT6/LMNA/CXCL12 signaling pathway regulated the osteo/odontogenic differentiation ability in dental stem cells isolated from apical papilla.

Tooth loss and maxillofacial bone defect are common diseases, which seriously affect people's health. Effective tooth and maxillofacial bone tissue regeneration is a key problem that need to be solved. In the present study, we investigate the role of PRMT6 in osteo/odontogenic differentiation and migration capacity by using SCAPs. Our results showed that knockdown of PRMT6 promoted the osteo/odontogenic differentiation compared with the control group, as detected by alkaline phosphatase activity, alizarin red staining, and the indicators of osteo/odontogenic differentiation measured by Western blot. In addition, overexpression of PRMT6 inhibited the osteo/odontogenic differentiation potentials of SCAPs. Then, knockdown of PRMT6 promoted the migration ability and overexpression of PRMT6 inhibited the migration ability in SCAPs. Mechanically, we discovered that the depletion of PRMT6 promoted the expression of CXCL12 by decreasing H3R2 methylation in the promoter region of CXCL12. In addition, PRMT6 formed a protein complex with LMNA, a nuclear structural protein. Depletion of LMNA inhibited the osteo/odontogenic differentiation and CXCL12 expression and increased the intranucleus PRMT6 in SCAPs. To sum up, PRMT6 might inhibit the osteo/odontogenic differentiation and migration ability of SCAPs via inhibiting CXCL12. And LMNA might be a negative regulator of PRMT6. It is suggested that PRMT6 may be a key target for SCAP-mediated bone and tooth tissue regeneration.

The Emerging Role of PRMT6 in Cancer.

Protein arginine methyltransferase 6 (PRMT6) is a type I PRMT that is involved in epigenetic regulation of gene expression through methylating histone or non-histone proteins, and other processes such as alternative splicing, DNA repair, cell proliferation and senescence, and cell signaling. In addition, PRMT6 also plays different roles in various cancers via influencing cell growth, migration, invasion, apoptosis, and drug resistant, which make PRMT6 an anti-tumor therapeutic target for a variety of cancers. As a result, many PRMT6 inhibitors are being utilized to explore their efficacy as potential drugs for various cancers. In this review, we summarize the current knowledge on the function and structure of PRMT6. At the same time, we highlight the role of PRMT6 in different cancers, including the differentiation of its promotive or inhibitory effects and the underlying mechanisms. Apart from the above, current research progress and the potential mechanisms of PRMT6 behind them were also summarized.