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Cell Research Aug 2023N-Methyldeoxyadenine (6mA) has been rediscovered as a DNA modification with potential biological function in metazoans. However, the physiological function and...
N-Methyldeoxyadenine (6mA) has been rediscovered as a DNA modification with potential biological function in metazoans. However, the physiological function and regulatory mechanisms regarding the establishment, maintenance and removal of 6mA in eukaryotes are still poorly understood. Here we show that genomic 6mA levels change in response to pathogenic infection in Caenorhabditis elegans (C. elegans). We further identify METL-9 as the methyltransferase that catalyzes DNA 6mA modifications upon pathogen infection. Deficiency of METL-9 impairs the induction of innate immune response genes and renders the animals more susceptible to pathogen infection. Interestingly, METL-9 functions through both 6mA-dependent and -independent mechanisms to transcriptionally regulate innate immunity. Our findings reveal that 6mA is a functional DNA modification in immunomodulation in C. elegans.
Topics: Animals; Caenorhabditis elegans; Methyltransferases; DNA Methylation; DNA; Immunity, Innate; Caenorhabditis elegans Proteins
PubMed: 37271765
DOI: 10.1038/s41422-023-00826-y -
Nature Cell Biology Mar 2024Type 1 diabetes (T1D) is characterized by the destruction of pancreatic β-cells. Several observations have renewed the interest in β-cell RNA sensors and editors....
Type 1 diabetes (T1D) is characterized by the destruction of pancreatic β-cells. Several observations have renewed the interest in β-cell RNA sensors and editors. Here, we report that N-methyladenosine (mA) is an adaptive β-cell safeguard mechanism that controls the amplitude and duration of the antiviral innate immune response at T1D onset. mA writer methyltransferase 3 (METTL3) levels increase drastically in β-cells at T1D onset but rapidly decline with disease progression. mA sequencing revealed the mA hypermethylation of several key innate immune mediators, including OAS1, OAS2, OAS3 and ADAR1 in human islets and EndoC-βH1 cells at T1D onset. METTL3 silencing enhanced 2'-5'-oligoadenylate synthetase levels by increasing its mRNA stability. Consistently, in vivo gene therapy to prolong Mettl3 overexpression specifically in β-cells delayed diabetes progression in the non-obese diabetic mouse model of T1D. Mechanistically, the accumulation of reactive oxygen species blocked upregulation of METTL3 in response to cytokines, while physiological levels of nitric oxide enhanced METTL3 levels and activity. Furthermore, we report that the cysteines in position C276 and C326 in the zinc finger domains of the METTL3 protein are sensitive to S-nitrosylation and are important to the METTL3-mediated regulation of oligoadenylate synthase mRNA stability in human β-cells. Collectively, we report that mA regulates the innate immune response at the β-cell level during the onset of T1D in humans.
Topics: Animals; Humans; Mice; Adenosine Deaminase; Diabetes Mellitus, Type 1; Immunity, Innate; Insulin-Secreting Cells; Methyltransferases; Oxidation-Reduction
PubMed: 38409327
DOI: 10.1038/s41556-024-01368-0 -
Cell Reports Nov 2023Development is regulated by various factors, including protein methylation status. While PRMT5 is well known for its roles in oncogenesis by mediating symmetric...
Development is regulated by various factors, including protein methylation status. While PRMT5 is well known for its roles in oncogenesis by mediating symmetric di-methylation of arginine, its role in normal development remains elusive. Using Myod1 to drive Prmt5 knockout in embryonic myoblasts (Prmt5), we dissected the role of PRMT5 in myogenesis. The Prmt5 mice are born normally but exhibit progressive muscle atrophy and premature death. Prmt5 inhibits proliferation and promotes premature differentiation of embryonic myoblasts, reducing the number and regenerative function of satellite cells in postnatal mice. Mechanistically, PRMT5 methylates and destabilizes FoxO1. Prmt5 increases the total FoxO1 level and promotes its cytoplasmic accumulation, leading to activation of autophagy and depletion of lipid droplets (LDs). Systemic inhibition of autophagy in Prmt5 mice restores LDs in myoblasts and moderately improves muscle regeneration. Together, PRMT5 is essential for muscle development and regeneration at least partially through mediating FoxO1 methylation and LD turnover.
Topics: Animals; Mice; Autophagy; Cell Differentiation; Methylation; Myoblasts; Protein-Arginine N-Methyltransferases
PubMed: 37883229
DOI: 10.1016/j.celrep.2023.113329 -
Clinical and Translational Medicine Jul 2023Energy balance has long been known to extend lifespans and inhibit carcinogenesis in multiple species by slowing age-related epigenetic changes while the underlying...
BACKGROUND
Energy balance has long been known to extend lifespans and inhibit carcinogenesis in multiple species by slowing age-related epigenetic changes while the underlying mechanisms remain largely unknown. Herein, we found that starvation activated autophagy to remodel the DNA methylation profile by inhibiting DNMT3a expression.
METHODS
Illumina Infinium MethylationEPIC BeadChip and dot blot assay were performed to quantify the global DNA methylation level. Protein-RNA interactions were validated through RNA immunoprecipitation and RNA pull-down assay. In vitro and in vivo experiments were carried out to testify the effect of DNMT3a on chemoresistance.
RESULTS
Autophagy is impaired in chemoresistance which was associated with differential DNA methylation and could be reversed by DNMT3a inhibition. Autophagy activation decreases the expression of DNMT3a mRNA, accompanied with the downregulation of chemoresistance-related Linc00942. Knockdown of Linc00942 reduces DNMT3a expression and genome-wide DNA methylation while Linc00942 overexpression increased DNMT3a expression and correlated hypermethylation in cancer cells and primary tumour tissues. Mechanistically, Linc00942 recruits RNA methyltransferase METTL3 to stimulate N6-methyladenosine (m6A) deposit on DNMT3a transcripts, triggering IGF2BP3/HuR to recognize modified mRNA for reinforced stability. SQSTM1/p62 recruits Linc00942 for autophagic degradation which can be abrogated after autophagy inhibition by p62 knockdown or chloroquine treatment.
CONCLUSIONS
Inhibition of autophagy increases Linc00942 expression to promote chemoresistance and autophagy activation or hypomethylating agent decitabine restores chemosensitivity by reducing global DNA methylation. Overall, this study identifies a novel methylation cascade linking impaired RNautophagy to global hypermethylation in chemoresistance, and provides a rationale for repurposing decitabine to overcome chemoresistance in cancer treatment.
Topics: Humans; DNA Methylation; Stomach Neoplasms; Drug Resistance, Neoplasm; Decitabine; RNA; RNA, Messenger; Methyltransferases
PubMed: 37477089
DOI: 10.1002/ctm2.1337 -
Molecular Cell Sep 2023Heritable non-genetic information can regulate a variety of complex phenotypes. However, what specific non-genetic cues are transmitted from parents to their descendants...
Heritable non-genetic information can regulate a variety of complex phenotypes. However, what specific non-genetic cues are transmitted from parents to their descendants are poorly understood. Here, we perform metabolic methyl-labeling experiments to track the heritable transmission of methylation from ancestors to their descendants in the nematode Caenorhabditis elegans (C. elegans). We find heritable methylation in DNA, RNA, proteins, and lipids. We find that parental starvation elicits reduced fertility, increased heat stress resistance, and extended longevity in fed, naïve progeny. This intergenerational hormesis is accompanied by a heritable increase in N6'-dimethyl adenosine (mA) on the 18S ribosomal RNA at adenosines 1735 and 1736. We identified DIMT-1/DIMT1 as the mA and BUD-23/BUD23 as the mG methyltransferases in C. elegans that are both required for intergenerational hormesis, while other rRNA methyltransferases are dispensable. This study labels and tracks heritable non-genetic material across generations and demonstrates the importance of rRNA methylation for regulating epigenetic inheritance.
Topics: Animals; RNA, Ribosomal, 18S; Caenorhabditis elegans; Hormesis; Methyltransferases; Adenosine
PubMed: 37689068
DOI: 10.1016/j.molcel.2023.08.014 -
Molecular Therapy : the Journal of the... Nov 2023Graft-versus-host disease (GVHD) is a common complication after allogeneic hematopoietic stem cell transplantation. Recent studies have reported that protein arginine...
Graft-versus-host disease (GVHD) is a common complication after allogeneic hematopoietic stem cell transplantation. Recent studies have reported that protein arginine methyltransferase 1 (PRMT1) is essential for the differentiation and proliferation of T and B cells. Therefore, it is possible that PRMT1 may play a critical role in GVHD. In this study, we observed that PRMT1 expression was upregulated in CD4 T and B cells from chronic GVHD (cGVHD) patients and mice. However, the prophylactic use of a PRMT1 inhibitor significantly prevented cGVHD in mice by reducing the percentage of T helper (Th)17 cells, germinal center B cells, and plasma cells. The PRMT1 inhibitor also controlled acute GVHD (aGVHD) in mice by decreasing the percentage of Th17 cells. Moreover, inhibiting PRMT1 also weakened Th17 cell differentiation, B cell proliferation, and antibody production in cells from cGVHD patients. Additionally, further studies revealed that PRMT1 regulated B cell proliferation and antibody secretion by methylating isocitrate dehydrogenase 2 (IDH2). We observed asymmetric di-methylation of IDH2 by PRMT1 at arginine 353 promoted IDH2 homodimerization, which enhanced IDH2 activity, further increasing B cell proliferation and antibody production. Collectively, this study provides a rationale for the application of PRMT1 inhibitors in the prevention of aGVHD and cGVHD.
Topics: Humans; Animals; Mice; Bronchiolitis Obliterans Syndrome; Hematopoietic Stem Cell Transplantation; Graft vs Host Disease; B-Lymphocytes; Plasma Cells; Methyltransferases; Protein-Arginine N-Methyltransferases; Repressor Proteins
PubMed: 37735873
DOI: 10.1016/j.ymthe.2023.09.011 -
The Journal of Biological Chemistry Sep 2023Coactivator-associated arginine methyltransferase 1 (CARM1) is an arginine methyltransferase that posttranslationally modifies proteins that regulate multiple levels of... (Review)
Review
Coactivator-associated arginine methyltransferase 1 (CARM1) is an arginine methyltransferase that posttranslationally modifies proteins that regulate multiple levels of RNA production and processing. Its substrates include histones, transcription factors, coregulators of transcription, and splicing factors. CARM1 is overexpressed in many different cancer types, and often promotes transcription factor programs that are co-opted as drivers of the transformed cell state, a process known as transcription factor addiction. Targeting these oncogenic transcription factor pathways is difficult but could be addressed by removing the activity of the key coactivators on which they rely. CARM1 is ubiquitously expressed, and its KO is less detrimental in embryonic development than deletion of the arginine methyltransferases protein arginine methyltransferase 1 and protein arginine methyltransferase 5, suggesting that therapeutic targeting of CARM1 may be well tolerated. Here, we will summarize the normal in vivo functions of CARM1 that have been gleaned from mouse studies, expand on the transcriptional pathways that are regulated by CARM1, and finally highlight recent studies that have identified oncogenic properties of CARM1 in different biological settings. This review is meant to kindle an interest in the development of human drug therapies targeting CARM1, as there are currently no CARM1 inhibitors available for use in clinical trials.
Topics: Animals; Humans; Mice; Drug Delivery Systems; Neoplasms; Transcription Factors; Protein-Arginine N-Methyltransferases
PubMed: 37536629
DOI: 10.1016/j.jbc.2023.105124 -
PLoS Pathogens Dec 2023Chronic hepatitis B virus (HBV) infection is a major cause of liver cirrhosis and liver cancer, despite strong prevention and treatment efforts. The study of the...
Chronic hepatitis B virus (HBV) infection is a major cause of liver cirrhosis and liver cancer, despite strong prevention and treatment efforts. The study of the epigenetic modification of HBV has become a research hotspot, including the N6-methyladenosine (m6A) modification of HBV RNA, which plays complex roles in the HBV life cycle. In addition to m6A modification, 5-methylcytosine (m5C) is another major modification of eukaryotic mRNA. In this study, we explored the roles of m5C methyltransferase and demethyltransferase in the HBV life cycle. The results showed that m5C methyltransferase NSUN2 deficiency could negatively regulate the expression of HBV while m5C demethyltransferase TET2 deficiency positively regulates the expression of HBV. Subsequently, we combined both in vitro bisulfite sequencing and high-throughput bisulfite sequencing methods to determine the distribution and stoichiometry of m5C modification in HBV RNA. Two sites: C2017 and C131 with the highest-ranking methylation rates were identified, and mutations at these two sites could lead to the decreased expression and replication of HBV, while the mutation of the "fake" m5C site had no effect. Mechanistically, NSUN2-mediated m5C modification promotes the stability of HBV RNA. In addition, compared with wild-type HepG2-NTCP cells and primary human hepatocytes, the replication level of HBV after NSUN2 knockdown decreased, and the ability of the mutant virus to infect and replicate in wild-type HepG2-NTCP cells and PHHs was substantially impaired. Similar results were found in the experiments using C57BL/6JGpt-Nsun2+/- mice. Interestingly, we also found that HBV expression and core protein promoted the endogenous expression of NSUN2, which implied a positive feedback loop. In summary, our study provides an accurate and high-resolution m5C profile of HBV RNA and reveals that NSUN2-mediated m5C modification of HBV RNA positively regulates HBV replication by maintaining RNA stability.
Topics: Animals; Humans; Mice; Hepatitis B virus; Hepatitis B, Chronic; Methyltransferases; Mice, Inbred C57BL; RNA
PubMed: 38048324
DOI: 10.1371/journal.ppat.1011808 -
Journal For Immunotherapy of Cancer Dec 2023Limited response to programmed death ligand-1 (PD-L1)/programmed death 1 (PD-1) immunotherapy is a major hindrance of checkpoint immunotherapy in non-small cell lung...
BACKGROUND
Limited response to programmed death ligand-1 (PD-L1)/programmed death 1 (PD-1) immunotherapy is a major hindrance of checkpoint immunotherapy in non-small cell lung cancer (NSCLC). The abundance of PD-L1 on the tumor cell surface is crucial for the responsiveness of PD-1/PD-L1 immunotherapy. However, the negative control of PD-L1 expression and the physiological significance of the PD-L1 inhibition in NSCLC immunotherapy remain obscure.
METHODS
Bioinformatics analysis was performed to profile and investigate the long non-coding RNAs that negatively correlated with PD-L1 expression and positively correlated with CD8+T cell infiltration in NSCLC. Immunofluorescence, PD-1 binding assay, T cell-induced apoptosis assays and syngeneic mouse models were used to investigate the functional roles of LINC02418 and mmu-4930573I07Rik in regulating anti-PD-L1 therapeutic efficacy in NSCLC. The molecular mechanism of LINC02418-enhanced PD-L1 downregulation was explored by immunoprecipitation, RNA immunoprecipitation (RIP), and ubiquitination assays. RIP, luciferase reporter, and messenger RNA degradation assays were used to investigate the m6A modification of LINC02418 or mmu-4930573I07Rik expression. Bioinformatics analysis and immunohistochemistry (IHC) verification were performed to determine the significance of LINC02418, PD-L1 expression and CD8+T cell infiltration.
RESULTS
LINC02418 is a negative regulator of PD-L1 expression that positively correlated with CD8+T cell infiltration, predicting favorable clinical outcomes for patients with NSCLC. LINC02418 downregulates PD-L1 expression by enhancing PD-L1 ubiquitination mediated by E3 ligase Trim21. Both hsa-LINC02418 and mmu-4930573I07Rik (its homologous RNA in mice) regulate PD-L1 therapeutic efficacy in NSCLC via Trim21, inducing T cell-induced apoptosis and . Furthermore, METTL3 inhibition via N6-methyladenosine (m6A) modification mediated by YTHDF2 reader upregulates hsa-LINC02418 and mmu-4930573I07Rik. In patients with NSCLC, LINC02418 expression is inversely correlated with PD-L1 expression and positively correlated with CD8+T infiltration.
CONCLUSION
LINC02418 functions as a negative regulator of PD-L1 expression in NSCLC cells by promoting the degradation of PD-L1 through the ubiquitin-proteasome pathway. The expression of LINC02418 is regulated by METTL3/YTHDF2-mediated m6A modification. This study illuminates the underlying mechanisms of PD-L1 negative regulation and presents a promising target for improving the effectiveness of anti-PD-L1 therapy in NSCLC.
Topics: Humans; Animals; Mice; Carcinoma, Non-Small-Cell Lung; Lung Neoplasms; B7-H1 Antigen; Programmed Cell Death 1 Receptor; Immunotherapy; RNA; Ubiquitination; Methyltransferases
PubMed: 38040417
DOI: 10.1136/jitc-2023-007415 -
Proceedings of the National Academy of... Aug 2023Dysregulation of histone lysine methyltransferases and demethylases is one of the major mechanisms driving the epigenetic reprogramming of transcriptional networks in...
Dysregulation of histone lysine methyltransferases and demethylases is one of the major mechanisms driving the epigenetic reprogramming of transcriptional networks in castration-resistant prostate cancer (CRPC). In addition to their canonical histone targets, some of these factors can modify critical transcription factors, further impacting oncogenic transcription programs. Our recent report demonstrated that LSD1 can demethylate the lysine 270 of FOXA1 in prostate cancer (PCa) cells, leading to the stabilization of FOXA1 chromatin binding. This process enhances the activities of the androgen receptor and other transcription factors that rely on FOXA1 as a pioneer factor. However, the identity of the methyltransferase responsible for FOXA1 methylation and negative regulation of the FOXA1-LSD1 oncogenic axis remains unknown. SETD7 was initially identified as a transcriptional activator through its methylation of histone 3 lysine 4, but its function as a methyltransferase on nonhistone substrates remains poorly understood, particularly in the context of PCa progression. In this study, we reveal that SETD7 primarily acts as a transcriptional repressor in CRPC cells by functioning as the major methyltransferase targeting FOXA1-K270. This methylation disrupts FOXA1-mediated transcription. Consistent with its molecular function, we found that SETD7 confers tumor suppressor activity in PCa cells. Moreover, loss of SETD7 expression is significantly associated with PCa progression and tumor aggressiveness. Overall, our study provides mechanistic insights into the tumor-suppressive and transcriptional repression activities of SETD7 in mediating PCa progression and therapy resistance.
Topics: Male; Humans; Histones; Prostatic Neoplasms, Castration-Resistant; Lysine; Receptors, Androgen; Methyltransferases; Histone Demethylases; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Histone-Lysine N-Methyltransferase; Hepatocyte Nuclear Factor 3-alpha
PubMed: 37549269
DOI: 10.1073/pnas.2220472120