Arginine methylation is a common post-translational modification functioning as an epigenetic regulator of transcription and playing key roles in pre-mRNA splicing, DNA damage signaling, mRNA ...translation, cell signaling, and cell fate decision. Recently, a wealth of studies using transgenic mouse models and selective PRMT inhibitors helped define physiological roles for protein arginine methyltransferases (PRMTs) linking them to diseases such as cancer and metabolic, neurodegenerative, and muscular disorders. This review describes the recent molecular advances that have been uncovered in normal and diseased mammalian cells.
Arginine methylation is a common modification regulating epigenetics and playing key roles in pre-mRNA splicing, translation, DNA damage, cell signaling, and cell fate decision. Blanc and Richard highlight studies that use transgenic mouse models and selective PRMT inhibitors to define physiological roles for protein arginine methyltransferases, linking them to diseases.
Aberrant transcription‐associated RNA:DNA hybrid (R‐loop) formation often causes catastrophic conflicts during replication, resulting in DNA double‐strand breaks and genomic instability. Preventing ...such conflicts requires hybrid dissolution by helicases and/or RNase H. Little is known about how such helicases are regulated. Herein, we identify DDX5, an RGG/RG motif‐containing DEAD‐box family RNA helicase, as crucial player in R‐loop resolution. In vitro, recombinant DDX5 resolves R‐loops in an ATP‐dependent manner, leading to R‐loop degradation by the XRN2 exoribonuclease. DDX5‐deficient cells accumulate R‐loops at loci with propensity to form such structures based on RNA:DNA immunoprecipitation (DRIP)‐qPCR, causing spontaneous DNA double‐strand breaks and hypersensitivity to replication stress. DDX5 associates with XRN2 and resolves R‐loops at transcriptional termination regions downstream of poly(A) sites, to facilitate RNA polymerase II release associated with transcriptional termination. Protein arginine methyltransferase 5 (PRMT5) binds and methylates DDX5 at its RGG/RG motif. This motif is required for DDX5 interaction with XRN2 and repression of cellular R‐loops, but not essential for DDX5 helicase enzymatic activity. PRMT5‐deficient cells accumulate R‐loops, resulting in increased formation of γH2AX foci. Our findings exemplify a mechanism by which an RNA helicase is modulated by arginine methylation to resolve R‐loops, and its potential role in regulating transcription.
Synopsis
Association of the helicase DDX5 and the nuclease XRN2 is dependent on PRMT5‐mediated arginine methylation of DDX5 and important for resolution of RNA/DNA hybrids at transcriptional termination regions, implicating this mechanism in XRN2‐mediated transcriptional termination.
PRMT5 inhibition leads to R‐loops accumulation and DNA damage.
Arginine methylation of the DDX5 RGG/RG motif regulates its association with XRN2 nuclease.
DDX5 functions with XRN2 to resolve R‐loops at transcription termination sites.
Recombinant DDX5 resolves R‐loops, but not D‐loops, in vitro via its helicase activity.
Association of DDX5 with XRN2 nuclease controlled by the methyltransferase PRMT5 is important for removing R‐loops at transcriptional termination regions.
Protein arginine methyltransferases (PRMTs) catalyze arginine methylation on both chromatin-bound and cytoplasmic proteins. Accumulating evidence supports the involvement of PRMT5, the major type II ...PRMT, in cell survival and differentiation pathways that are important during development and in tumorigenesis. PRMT5 is an attractive drug target in various cancers, and inhibitors are currently in oncological clinical trials. Nonetheless, given the complex biology of PRMT5 and its multiple nonhistone substrates, it is paramount to fully characterize these dynamic changes in methylation and to link them to the observed anticancer effects to fully understand the functions of PRMT5 and the consequences of its inhibition. Here, we used a newly established pipeline coupling stable isotope labeling with amino acids in cell culture (SILAC) with immunoenriched methyl peptides to globally profile arginine monomethylation and symmetric dimethylation after PRMT5 inhibition by a selective inhibitor. We adopted heavy methyl SILAC as an orthogonal validation method to reduce the false discovery rate. Through in vitro methylation assays, we validated a set of PRMT5 targets identified by mass spectrometry and provided previously unknown mechanistic insights into the preference of the enzyme to methylate arginine sandwiched between two neighboring glycines (a Gly-Arg-Gly, or "GRG," sequence). Our analysis led to the identification of previously unknown PRMT5 substrates, thus both providing insight into the global effects of PRMT5 and its inhibition in live cells, beyond chromatin, and refining our knowledge of its substrate specificity.
There are nine protein arginine methyltransferases (PRMTs) encoded in mammalian genomes, the protein products of which catalyse three types of arginine methylation--monomethylation and two types of ...dimethylation. Protein arginine methylation is an abundant modification that has been implicated in signal transduction, gene transcription, DNA repair and mRNA splicing, among others. Studies have only recently linked this modification to carcinogenesis and metastasis. Sequencing studies have not generally found alterations to the PRMTs; however, overexpression of these enzymes is often associated with various cancers, which might make some of them viable targets for therapeutic strategies.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The mammalian protein arginine methyltransferase 7 (PRMT7) has been implicated in roles of transcriptional regulation, DNA damage repair, RNA splicing, cell differentiation, and metastasis. However, ...the type of reaction that it catalyzes and its substrate specificity remain controversial. In this study, we purified a recombinant mouse PRMT7 expressed in insect cells that demonstrates a robust methyltransferase activity. Using a variety of substrates, we demonstrate that the enzyme only catalyzes the formation of ω-monomethylarginine residues, and we confirm its activity as the prototype type III protein arginine methyltransferase. This enzyme is active on all recombinant human core histones, but histone H2B is a highly preferred substrate. Analysis of the specific methylation sites within intact histone H2B and within H2B and H4 peptides revealed novel post-translational modification sites and a unique specificity of PRMT7 for methylating arginine residues in lysine- and arginine-rich regions. We demonstrate that a prominent substrate recognition motif consists of a pair of arginine residues separated by one residue (RXR motif). These findings will significantly accelerate substrate profile analysis, biological function study, and inhibitor discovery for PRMT7.
Background: Protein arginine methyltransferase 7 (PRMT7) is associated with various functions and diseases, but its substrate specificity is poorly defined.
Results: Insect cell-expressed PRMT7 forms ω-monomethylarginine residues at basic RXR sequences in peptides and histone H2B.
Conclusion: PRMT7 is a type III PRMT with a unique substrate specificity.
Significance: Novel post-translational modification sites generated by PRMT7 may regulate biological function.
Stress granules (SGs) are cytoplasmic condensates of stalled messenger ribonucleoprotein complexes (mRNPs) that form when eukaryotic cells encounter environmental stress. RNA-binding proteins are ...enriched for arginine methylation and facilitate SG assembly through interactions involving regions of low amino acid complexity. How methylation of specific RNA-binding proteins regulates RNA granule assembly has not been characterized. Here, we examined the potent SG-nucleating protein Ras-GAP SH3-binding protein 1 (G3BP1), and found that G3BP1 is differentially methylated on specific arginine residues by protein arginine methyltransferase (PRMT) 1 and PRMT5 in its RGG domain. Several genetic and biochemical interventions that increased methylation repressed SG assembly, whereas interventions that decreased methylation promoted SG assembly. Arsenite stress quickly and reversibly decreased asymmetric arginine methylation on G3BP1. These data indicate that arginine methylation in the RGG domain prevents large SG assembly and rapid demethylation is a novel signal that regulates SG formation.
Post-translational modifications (PTM) are the evolutionary solution to challenge and extend the boundaries of genetically predetermined proteomic diversity. As PTMs are highly dynamic, they also ...hold an enormous regulatory potential. It is therefore not surprising that out of the 20 proteinogenic amino acids, 15 can be post-translationally modified. Even the relatively inert guanidino group of arginine is subject to a multitude of mostly enzyme mediated chemical changes. The resulting alterations can have a major influence on protein function. In this review, we will discuss how bacteria control their cellular processes and develop pathogenicity based on post-translational protein-arginine modifications.
Protein arginine methyltransferase 1 (PRMT1), a major type I arginine methyltransferase in mammals, methylates histone and non-histone proteins to regulate various cellular functions such as ...transcription, DNA damage response, and signal transduction.
This review summarizes previous and recent studies on PRMT1 functions in major cell types of the central nervous system. We also discuss the potential involvement of PRMT1 in neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal dementia. Also, we raise key questions that must be addressed in the future to more precisely understand the roles of PRMT1.
Recent studies revealed that PRMT1 is essential for the development of neurons, astrocytes, and oligodendrocytes, although further investigation using cell type-specific PRMT1-deficient animals is required. In addition, the relevance of PRMT1 in neurodegenerative diseases will continue to be a hot topic.
PRMT1 is important for neural development and neurodegenerative diseases.
•PRMT1 catalyzes asymmetric dimethylation of arginine residues of proteins.•PRMT1 in neural stem cells is essential for early brain development.•Arginine methylation by PRMT1 and 5 are indispensable for myelination.•Methylation reduces phase separation of neurodegeneration-causative factors.•Methyl-arginine-specific antibodies and chemical tools accelerate PRMT study.
Protein arginine methyltransferases (PRMTs) catalyze the methyl transfer to the arginine residues of protein substrates and are classified into three major types based on the final form of the ...methylated arginine. Recent studies have shown a strong correlation between PRMT expression level and the prognosis of cancer patients. Currently, crystal structures of eight PRMT members have been determined. Kinetic and structural studies have shown that all PRMTs share similar, but unique catalytic and substrate recognition mechanism. In this review, we discuss the structural similarities and differences of different PRMT members, focusing on their overall structure,
S
-adenosyl-
l
-methionine-binding pocket, substrate arginine recognition and catalytic mechanisms. Since PRMTs are valuable targets for drug discovery, we also rationally classify the known PRMT inhibitors into five classes and discuss their mechanisms of action at the atomic level.
Drug resistance remains a major challenge in cancer treatment, necessitating the development of novel strategies to overcome it. Protein arginine methyltransferases (PRMTs) are enzymes responsible ...for epigenetic arginine methylation, which regulates various biological and pathological processes, as a result, they are attractive therapeutic targets for overcoming anti-cancer drug resistance. The ongoing development of small molecules targeting PRMTs has resulted in the generation of chemical probes for modulating most PRMTs and facilitated clinical treatment for the most advanced oncology targets, including PRMT1 and PRMT5. In this review, we summarize various mechanisms underlying protein arginine methylation and the roles of specific PRMTs in driving cancer drug resistance. Furthermore, we highlight the potential clinical implications of PRMT inhibitors in decreasing cancer drug resistance. PRMTs promote the formation and maintenance of drug-tolerant cells via several mechanisms, including altered drug efflux transporters, autophagy, DNA damage repair, cancer stem cell-related function, epithelial-mesenchymal transition, and disordered tumor microenvironment. Multiple preclinical and ongoing clinical trials have demonstrated that PRMT inhibitors, particularly PRMT5 inhibitors, can sensitize cancer cells to various anti-cancer drugs, including chemotherapeutic, targeted therapeutic, and immunotherapeutic agents. Combining PRMT inhibitors with existing anti-cancer strategies will be a promising approach for overcoming anti-cancer drug resistance. Furthermore, enhanced knowledge of the complex functions of arginine methylation and PRMTs in drug resistance will guide the future development of PRMT inhibitors and may help identify new clinical indications.
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