ABSTRACT
RNA 5-methylcytosine (m5C) is an abundant chemical modification in mammalian RNAs and plays crucial roles in regulating vital physiological and pathological processes, especially in cancer. However, the dysregulation of m5C and its underlying mechanisms in non-small cell lung cancer (NSCLC) remain unclear. Here we identified that NSUN2, a key RNA m5C methyltransferase, is highly expressed in NSCLC tumor tissue. We found elevated NSUN2 expression levels strongly correlate with tumor grade and size, predicting poor outcomes for NSCLC patients. Furthermore, RNA-seq and subsequent confirmation studies revealed the antioxidant-promoting transcription factor NRF2 is a target of NSUN2, and depleting NSUN2 decreases the expression of NRF2 and increases the sensitivity of NSCLC cells to ferroptosis activators both in vitro and in vivo. Intriguingly, the methylated-RIP-qPCR assay results indicated that NRF2 mRNA has a higher m5C level when NSUN2 is overexpressed in NSCLC cells but shows no significant changes in the NSUN2 methyltransferase-deficient group. Mechanistically, we confirmed that NSUN2 upregulates the expression of NRF2 by enhancing the stability of NRF2 mRNA through the m5C modification within its 5'UTR region recognized by the specific m5C reader protein YBX1, rather than influencing its translation. In subsequent rescue experiments, we show knocking down NRF2 diminished the proliferation, migration, and ferroptosis tolerance mediated by NSUN2 overexpression. In conclusion, our study unveils a novel regulatory mechanism in which NSUN2 sustains NRF2 expression through an m5C-YBX1-axis, suggesting that targeting NSUN2 and its regulated ferroptosis pathway might offer promising therapeutic strategies for NSCLC patients.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Ferroptosis , Lung Neoplasms , NF-E2-Related Factor 2 , Animals , Humans , Mice , Carcinoma, Non-Small-Cell Lung/metabolism , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/pathology , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Lung Neoplasms/metabolism , Lung Neoplasms/pathology , Lung Neoplasms/genetics , Methyltransferases/metabolism , Methyltransferases/genetics , Mice, Nude , NF-E2-Related Factor 2/metabolism , NF-E2-Related Factor 2/genetics , Male , Female , Middle AgedABSTRACT
RNA methylation, an epigenetic modification that does not alter gene sequence, may be important to diverse biological processes. Protein regulators of RNA methylation include "writers," "erasers," and "readers," which respectively deposit, remove, and recognize methylated RNA. RNA methylation, particularly N6-methyladenosine (m6A), 5-methylcytosine (m5C), N3-methylcytosine (m3C), N1-methyladenosine (m1A) and N7-methylguanosine (m7G), has been suggested as disease therapeutic targets. Despite advances in the structure and pharmacology of RNA methylation regulators that have improved drug discovery, regulating these proteins by various post-translational modifications (PTMs) has received little attention. PTM modifies protein structure and function, affecting all aspects of normal biology and pathogenesis, including immunology, cell differentiation, DNA damage repair, and tumors. It is becoming evident that RNA methylation regulators are also regulated by diverse PTMs. PTM of RNA methylation regulators induces their covalent linkage to new functional groups, hence modifying their activity and function. Mass spectrometry has identified many PTMs on protein regulators of RNA methylation. In this review, we describe the functions and PTM of protein regulators of RNA methylation and summarize the recent advances in the regulatory mode of human disease and its underlying mechanisms.
Subject(s)
Epigenesis, Genetic , RNA , Humans , Methylation , RNA/genetics , Protein Processing, Post-Translational , Cell DifferentiationABSTRACT
Myocarditis is defined as an inflammatory disease of the myocardium, and the autoimmune response specific to myocardium plays an important role in chronic myocarditis. Inhibiting myocardial-specific autoimmune response and inflammation is crucial to treat myocarditis. Myricetin is a plant-derived flavonoid in nature which has potent anti-inflammatory and cardiovascular protective properties. However, the pharmacological effect of myricetin in autoimmune myocarditis is undefined. It is necessary to investigate the role and potential mechanisms of myricetin in autoimmune myocarditis. Therefore, purified cardiac myosin was subcutaneously injected to mice to establish the experimental autoimmune myocarditis (EAM) model. Myricetin was solubilized in normal saline and administered everyday by gavage from the day of immunization. After 21 days of treatment, it was found that myricetin significantly alleviated myocardial injury in EAM mice. The serum anti-cardiac myosin antibody, immunoglobulin (Ig) G, IgM levels and the proportion of T helper 17 (Th17) cells were decreased and the proportion of regulatory T (Treg) cells was increased with the treatment of myricetin in EAM mice. The myosin-specific T cell proliferation was inhibited by myricetin. Meanwhile, myricetin suppressed the expressions of monocyte chemoattractant protein-1 (MCP-1), phospho (p)-p65, p-c-Jun and Act1/TRAF6/TAK1 in H9C2 cells and myocardial tissues of EAM mice. These results revealed that myricetin inhibited the autoimmune response specific to myocardium and the expression of MCP-1 in cardiomyocytes, which suggested that myricetin ameliorated autoimmune myocarditis by modulating immune response and the expression of MCP-1. Therefore, myricetin may be a promising therapeutic strategy for autoimmune myocarditis.
