Quercetin ameliorated insulin resistance via regulating METTL3-mediated N6-methyladenosine modification of PRKD2 mRNA in skeletal muscle and C2C12 myocyte cell line

STM2457 decreases m6A methylation to reduce cisplatin-induced ototoxicity via MAPK signaling

Cisplatin, a chemotherapeutic drug used to treat cancerous solid tumors, can result in ototoxicity due to serious toxic side effects resulting in irreversible hearing loss. Here, we investigated the effects of N6-methyladenosine (m6A) methylation on cisplatin-induced ototoxicity by using in vitro cochlear explants as a model system to explore the effect of the Methyltransferase-like 3 (METTL3) inhibitor STM2457 in ameliorating cisplatin-induced ototoxicity. STM2457 pretreatment was shown to significantly reduce reactive oxygen species (ROS) accumulation and the loss of hair cells (HCs) in different regions of the organ of Corti. STM2457 pretreatment led to significant reductions in TUNEL labeling, signifying a reduction in apoptosis. Additionally, expression of the apoptosis-related protein BAX was significantly decreased, while the ratio of BCL-XL was markedly increased. Transcriptomic measurements of the STM2457 + cisplatin group revealed significant enrichment of the Mitogen-Activated Protein Kinases (MAPK) signaling pathway, which when stimulated, could block the protective effect of STM2457 in cisplatin-treated HCs. Thus, we describe a mechanism by which STM2457 decreases cisplatin-related HC death in cochlear explants in vitro through activation of the MAPK pathway. This study reports for the first time that reducing RNA m6A methylation might protects against cisplatin-induced ototoxicity. Our data indicate that STM2457 can serve as an effect anti-apoptotic drug to decrease ototoxicity caused by cisplatin-induced ROS accumulation, effectively preventing cisplatin-induced hair cells loss.

The Role of N6-Methyladenosine in Mitochondrial Dysfunction and Pathology

Mitochondria are indispensable in cells and play crucial roles in maintaining cellular homeostasis, energy production, and regulating cell death. Mitochondrial dysfunction has various manifestations, causing different diseases by affecting the diverse functions of mitochondria in the body. Previous studies have mainly focused on mitochondrial-related diseases caused by nuclear gene mutations or mitochondrial gene mutations, or mitochondrial dysfunction resulting from epigenetic regulation, such as DNA and histone modification. In recent years, as a popular research area, m6A has been involved in a variety of important processes under physiological and pathological conditions. However, there are few summaries on how RNA methylation, especially m6A RNA methylation, affects mitochondrial function. Additionally, the role of m6A in pathology through influencing mitochondrial function may provide us with a new perspective on disease treatment. In this review, we summarize several manifestations of mitochondrial dysfunction and compile examples from recent years of how m6A affects mitochondrial function and its role in some diseases.

Quercetin attenuated necroptosis and apoptosis caused by LPS-induced mitochondrial function dysfunction through the METTL3-mediated PTEN m6A methylation/PI3K/AKT signaling in broiler livers

BACKGROUND

Quercetin (QUE), a natural flavonoid, offered an efficient protection against organism injury. N6-methyladenosine (m6A) methylation is considered to be the most prevalent and abundant modifications involved in various diseases.

PURPOSE

We sought to explore protective roles of QUE in mitigating necroptosis and apoptosis triggered by LPS-induced imbalances in mitochondria dynamic and energy metabolism in broiler livers, with a focus on m6A methylation modulation.

STUDY DESIGN/METHODS

We used LPS as a stimulus and treated with QUE to establish this in vivo and in vitro. In addition, we treated LMH cells with siMETTL3 (80 nM) to determine its detailed mechanism.

RESULTS

Our findings revealed QUE significantly decreased METTL3 expression, leading to a decrease in PTEN m6A methylation and factors related to mitochondria fission, necroptosis, and apoptosis in the QUE+LPS group. In contrast, QUE treatment promoted the expression levels of marker factors for mitochondria fusion, energy metabolism, anti-apoptosis, and PI3K/AKT compared with the LPS group. Additionally, an increase of ΔΨm, ATP content, and ATPase activity was observed. AO/EB staining, Flow cytometry and TUNEL assays confirmed QUE inhibited LPS-induced apoptosis and necroptosis. Molecular docking analysis and cellular thermal shift assay supported an interaction between QUE and METTL3.

CONCLUSION

In summary, QUE mitigated necroptosis and apoptosis triggered by LPS-induced disorders of mitochondrial kinetic and metabolic processes in broiler livers through its interaction with METTL3, regulating PTEN m6A methylation/PI3K/AKT signaling pathway. This study enhances our understanding of biological functions for QUE and lays a theoretical foundation for developing new therapeutic interventions, highlighting its potential value.

Unraveling Quercetin's Potential: A Comprehensive Review of Its Properties and Mechanisms of Action, in Diabetes and Obesity Complications

The prevalence of diabetes is escalating alarmingly, placing a significant economic burden on the global healthcare system. The use of chemical substances extracted from plants has been demonstrated to be an effective method for the treatment and control of insulin resistance and Type 2 diabetes mellitus (T2DM). New research indicates that natural phytochemicals present in fruits and vegetables are expected to become drugs for the treatment of diabetes and the prevention of related complications. Quercetin, a widely distributed flavonoid, is well-known for its antioxidant, anti-inflammatory, anticancer, and antidiabetic properties. This article provides a comprehensive account of the mechanism of action of quercetin on diabetes and obesity complications in vivo and in vitro. It elucidates the impact of quercetin on various cells. These include hepatocytes, renal cells, skeletal muscle cells, and adipocytes. Furthermore, this article discusses the mechanism of quercetin on organ damage in diabetic mice induced by STZ, alloxan, diet, and spontaneous Type 2 diabetic mice caused by genetic defects. Additionally, it addresses the pharmacokinetics of quercetin and its potential for synergistic effects with existing diabetic drugs.

Identification and Characterisation of Potential Targets for N6-methyladenosine (m6A) Modification during Intervertebral Disc Degeneration

BACKGROUND

The mechanism for RNA methylation during disc degeneration is unclear. The aim of this study was to identify N6-methyladenosine (m6A) markers and therapeutic targets for the prevention and treatment of intervertebral disc degeneration (IDD).

METHODS

Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and quantitative reverse transcription PCR (RT-qPCR) were employed to analyze m6A modifications of IDD-related gene expression. Bioinformatics was used to identify enriched gene pathways in IDD. m6A-RIP-qPCR was used to validate potential targets and markers.

RESULTS AND CONCLUSION

Human IDD samples exhibited a distinct m6A modification pattern that allowed associated genes and pathways to be identified. These genes had functions such as "nuclear factor kappa-B (NF-κB) binding" and "extracellular matrix components", which are crucial for IDD pathogenesis. ANXA2 showed increased m6A modification in IDD, while SLC3A2 and PBX3 showed decreased m6A methylation. The results of this study offer novel insights for the prevention and treatment of IDD.

Epigenetics-targeted drugs: current paradigms and future challenges

Epigenetics governs a chromatin state regulatory system through five key mechanisms: DNA modification, histone modification, RNA modification, chromatin remodeling, and non-coding RNA regulation. These mechanisms and their associated enzymes convey genetic information independently of DNA base sequences, playing essential roles in organismal development and homeostasis. Conversely, disruptions in epigenetic landscapes critically influence the pathogenesis of various human diseases. This understanding has laid a robust theoretical groundwork for developing drugs that target epigenetics-modifying enzymes in pathological conditions. Over the past two decades, a growing array of small molecule drugs targeting epigenetic enzymes such as DNA methyltransferase, histone deacetylase, isocitrate dehydrogenase, and enhancer of zeste homolog 2, have been thoroughly investigated and implemented as therapeutic options, particularly in oncology. Additionally, numerous epigenetics-targeted drugs are undergoing clinical trials, offering promising prospects for clinical benefits. This review delineates the roles of epigenetics in physiological and pathological contexts and underscores pioneering studies on the discovery and clinical implementation of epigenetics-targeted drugs. These include inhibitors, agonists, degraders, and multitarget agents, aiming to identify practical challenges and promising avenues for future research. Ultimately, this review aims to deepen the understanding of epigenetics-oriented therapeutic strategies and their further application in clinical settings.

Protein kinase D2 modulates hepatic insulin sensitivity in male mice

OBJECTIVES

Protein kinase D (PKD) family is emerging as relevant regulator of metabolic homeostasis. However, the precise role of PKD2 in modulating hepatic insulin signaling has not been fully elucidated and it is the aim of this study.

METHODS

PKD inhibition was analyzed for insulin signaling in mouse and human hepatocytes. PKD2 was overexpressed in Huh7 hepatocytes and mouse liver, and insulin responses were evaluated. Mice with hepatocyte-specific PKD2 depletion (PKD2ΔHep) and PKD2fl/fl mice were fed a chow (CHD) or high fat diet (HFD) and glucose homeostasis and lipid metabolism were investigated.

RESULTS

PKD2 silencing enhanced insulin signaling in hepatocytes, an effect also found in primary hepatocytes from PKD2ΔHep mice. Conversely, a constitutively active PKD2 mutant reduced insulin-stimulated AKT phosphorylation. A more in-depth analysis revealed reduced IRS1 serine phosphorylation under basal conditions and increased IRS1 tyrosine phosphorylation in PKD2ΔHep primary hepatocytes upon insulin stimulation and, importantly PKD co-immunoprecipitates with IRS1. In vivo constitutively active PKD2 overexpression resulted in a moderate impairment of glucose homeostasis and reduced insulin signaling in the liver. On the contrary, HFD-fed PKD2ΔHep male mice displayed improved glucose and pyruvate tolerance, as well as higher peripheral insulin tolerance and enhanced hepatic insulin signaling compared to control PKD2fl/fl mice. Despite of a remodeling of hepatic lipid metabolism in HFD-fed PKD2ΔHep mice, similar steatosis grade was found in both genotypes.

CONCLUSIONS

Results herein have unveiled an unknown role of PKD2 in the control of insulin signaling in the liver at the level of IRS1 and point PKD2 as a therapeutic target for hepatic insulin resistance.

Comprehensive review on lipid metabolism and RNA methylation: Biological mechanisms, perspectives and challenges

Adipose tissue plays a crucial role in maintaining energy balance, regulating hormones, and promoting metabolic health. To address disorders related to obesity and develop effective therapies, it is essential to have a deep understanding of adipose tissue biology. In recent years, RNA methylation has emerged as a significant epigenetic modification involved in various cellular functions and metabolic pathways. Particularly in the realm of adipogenesis and lipid metabolism, extensive research is ongoing to uncover the mechanisms and functional importance of RNA methylation. Increasing evidence suggests that RNA methylation plays a regulatory role in adipocyte development, metabolism, and lipid utilization across different organs. This comprehensive review aims to provide an overview of common RNA methylation modifications, their occurrences, and regulatory mechanisms, focusing specifically on their intricate connections to fat metabolism. Additionally, we discuss the research methodologies used in studying RNA methylation and highlight relevant databases that can aid researchers in this rapidly advancing field.

RNA modifications in cellular metabolism: implications for metabolism-targeted therapy and immunotherapy

Cellular metabolism is an intricate network satisfying bioenergetic and biosynthesis requirements of cells. Relevant studies have been constantly making inroads in our understanding of pathophysiology, and inspiring development of therapeutics. As a crucial component of epigenetics at post-transcription level, RNA modification significantly determines RNA fates, further affecting various biological processes and cellular phenotypes. To be noted, immunometabolism defines the metabolic alterations occur on immune cells in different stages and immunological contexts. In this review, we characterize the distribution features, modifying mechanisms and biological functions of 8 RNA modifications, including N6-methyladenosine (m6A), N6,2'-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N4-acetylcytosine (ac4C), N7-methylguanosine (m7G), Pseudouridine (Ψ), adenosine-to-inosine (A-to-I) editing, which are relatively the most studied types. Then regulatory roles of these RNA modification on metabolism in diverse health and disease contexts are comprehensively described, categorized as glucose, lipid, amino acid, and mitochondrial metabolism. And we highlight the regulation of RNA modifications on immunometabolism, further influencing immune responses. Above all, we provide a thorough discussion about clinical implications of RNA modification in metabolism-targeted therapy and immunotherapy, progression of RNA modification-targeted agents, and its potential in RNA-targeted therapeutics. Eventually, we give legitimate perspectives for future researches in this field from methodological requirements, mechanistic insights, to therapeutic applications.

Regulatory effects of natural products on N6-methyladenosine modification: A novel therapeutic strategy for cancer

N6-methyladenosine (m6A) is considered to be the most common and abundant epigenetics modification in messenger RNA (mRNA) and noncoding RNA. Abnormal modification of m6A is closely related to the occurrence, development, progression, and prognosis of cancer. m6A regulators have been identified as novel targets for anticancer drugs. Natural products, a rich source of traditional anticancer drugs, have been utilized for the development of m6A-targeting drugs. Here, we review the key role of m6A modification in cancer progression and explore the prospects and structural modification mechanisms of natural products as potential drugs targeting m6A modification for cancer treatment.

Emerging role of N6-methyladenosine in the homeostasis of glucose metabolism

N6-methyladenosine (m6A) is the most prevalent post-transcriptional internal RNA modification, which is involved in the regulation of diverse physiological processes. Dynamic and reversible m6A modification has been shown to regulate glucose metabolism, and dysregulation of m6A modification contributes to glucose metabolic disorders in multiple organs and tissues including the pancreas, liver, adipose tissue, skeletal muscle, kidney, blood vessels, and so forth. In this review, the role and molecular mechanism of m6A modification in the regulation of glucose metabolism were summarized, the potential therapeutic strategies that improve glucose metabolism by targeting m6A modifiers were outlined, and feasible directions of future research in this field were discussed as well, providing clues for translational research on combating metabolic diseases based on m6A modification in the future.

Hallmarks of Quercetin Benefits as a Functional Supplementary in the Management of Diabetes Mellitus-Related Maladies: From Basic to Clinical Applications

Quercetin (QE), a particular flavonoid, is well known for its medicinal effects, including anti-oxidant, hypoglycemic, and anti-inflammatory effects. In this review, the findings of QE effects on diabetes STZinduced, alloxan-induced, and its complications have been summarized with a particular focus on in vitro, in vivo, and clinical trials. Consequently, QE mediates several mechanisms, including ameliorating tumor necrosis factor (TNF)-α, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukin (IL)-1β, IL-8, and IL-10 expression, increasing insulin glucose uptake to inhibit insulin resistance. Moreover, QE stimulates insulin secretion and attenuates insulin resistance through various pathways, namely transient KATP channel, motivating peroxisome proliferator-activated receptor expression, increasing glucose transporter-4, and decreasing inducible nitric oxide synthase in skeletal muscle. QE has protective effects on the complications caused by diabetes, such as polycystic ovary syndrome, high-fat diet-induced obesity, diabetic-induced hepatic damage, vascular inflammation, nephropathy, and neuropathy.

Epigenetic regulation by quercetin: a comprehensive review focused on its biological mechanisms

Epigenetics regulates gene expression and play significant roles across diverse disease states. Epigenetics mechanisms, including DNA methylation, histone modifications, microRNAs/lncRNA, and N6-methyladenosine (m6A) RNA methylation, elicit heritable but reversible modifications in gene expression without modifying the DNA sequence. Recent research suggests that certain natural phytochemicals with chemopreventive properties have the potential to function as epigenetic regulators. Quercetin, a derivative of natural flavonoid glycosides and a constituent of the human diet, is linked to a variety of health benefits including anti-inflammatory, anticancer activity, antiapoptotic, antihypertensive, and neuroprotective effects. Recent findings suggest that quercetin possesses the ability to modulate canonical biochemical signaling pathways and exert an impact on epigenetic networks. This review aims to synthesize the most recent research findings that elucidate the potential biological effects of quercetin and its influence on in vitro and in vivo models via epigenetic mechanisms. In light of our findings, it is evident that quercetin possesses the potential to function as an exemplary instance of naturally derived phytochemicals, which can be effectively employed as a pivotal constituent in functional foods and dietary supplements aimed at the amelioration of various ailments. More specifically, its mechanism of action involves the alteration of diverse epigenetic targets.

m6 A mRNA methylation: Biological features, mechanisms, and therapeutic potentials in type 2 diabetes mellitus

As the most common internal post-transcriptional RNA modification in eukaryotic cells, N6-methyladenosine (m6 A) performs a dynamic and reversible role in a variety of biological processes mediated by methyltransferases (writers), demethylases (erasers), and m6 A binding proteins (readers). M6 A methylation enables transcriptome conversion in different signals that regulate various physiological activities and organ development. Over the past few years, emerging studies have identified that mRNA m6 A regulators defect in β-cell leads to abnormal regulation of the target mRNAs, thereby resulting in β-cell dysfunction and loss of β-cell identity and mass, which are strongly associated with type 2 diabetes mellitus (T2DM) pathogenesis. Also, mRNA m6 A modification has been implicated with insulin resistance in muscles, fat, and liver cells/tissues. In this review, we elaborate on the biological features of m6 A methylation; provide a comprehensive overview of the underlying mechanisms that how it controls β-cell function, identity, and mass as well as insulin resistance; highlight its connections to glucose metabolism and lipid metabolism linking to T2DM; and further discuss its role in diabetes complications and its therapeutic potentials for T2DM diagnosis and treatment.

Insights into RNA N6-methyladenosine in Glucose and Lipid Metabolic Diseases and Their Therapeutic Strategies

The incidence of glucose and lipid metabolism diseases, including type 2 diabetes, obesity, metabolic syndrome, and nonalcoholic fatty liver disease, is rising, which places an enormous burden on people around the world. However, the mechanism behind these disorders remains incompletely understood. N6-methyladenosine (m6A) is 1 type of posttranscriptional RNA modification, and research has shown that it plays a crucial role in several metabolic diseases. m6A methylation is reversibly and dynamically regulated by methyltransferases (writers), demethylases (erasers), and m6A binding proteins (readers). Dysregulation of RNA m6A modification is related to different metabolic processes. Targeting RNA m6A methylation is a potential treatment strategy for these chronic metabolic diseases. This review discusses studies on RNA m6A modification in metabolic diseases and existing therapeutic drugs, with the aim of providing a concise perspective on its potential applications in managing metabolic disorders.

Thymus atlanticus: A Source of Nutrients with Numerous Health Benefits and Important Therapeutic Potential for Age-Related Diseases

Thymus atlanticus (Lamiaceae) is a plant endemic to the Mediterranean basin that is found in significant quantities in the arid regions of Morocco. Thymus atlanticus is used in traditional medicine to treat infectious and non-infectious diseases. It is also used for the isolation of essential oils and for the seasoning of many dishes in the Mediterranean diet. The major constituents of Thymus atlanticus are saponins, flavonoids, tannins, alkaloids, various simple and hydroxycinnamic phenolic compounds, and terpene compounds. Several of these compounds act on signaling pathways of oxidative stress, inflammation, and blood sugar, which are parameters often dysregulated during aging. Due to its physiochemical characteristics and biological activities, Thymus atlanticus could be used for the prevention and/or treatment of age-related diseases. These different aspects are treated in the present review, and we focused on phytochemistry and major age-related diseases: dyslipidemia, cardiovascular diseases, and type 2 diabetes.

N6-methyladenosine RNA modification: an emerging molecule in type 2 diabetes metabolism

Type 2 diabetes (T2D) is a metabolic disease with an increasing rate of incidence worldwide. Despite the considerable progress in the prevention and intervention, T2D and its complications cannot be reversed easily after diagnosis, thereby necessitating an in-depth investigation of the pathophysiology. In recent years, the role of epigenetics has been increasingly demonstrated in the disease, of which N6-methyladenosine (m6A) is one of the most common post-transcriptional modifications. Interestingly, patients with T2D show a low m6A abundance. Thus, a comprehensive analysis and understanding of this phenomenon would improve our understanding of the pathophysiology, as well as the search for new biomarkers and therapeutic approaches for T2D. In this review, we systematically introduced the metabolic roles of m6A modification in organs, the metabolic signaling pathways involved, and the effects of clinical drugs on T2D.

A Descriptive Review of the Action Mechanisms of Berberine, Quercetin and Silymarin on Insulin Resistance/Hyperinsulinemia and Cardiovascular Prevention

Insulin resistance (IR) and the associated hyperinsulinemia are early pathophysiological changes which, if not well treated, can lead to type 2 diabetes, endothelial dysfunction and cardiovascular disease. While diabetes care is fairly well standardized, the prevention and treatment of IR lacks a single pharmaceutical approach and many lifestyle and dietary interventions have been proposed, including a wide range of food supplements. Among the most interesting and well-known natural remedies, alkaloid berberine and the flavonol quercetin have particular relevance in the literature, while silymarin-the active principle of the Silybum marianum thistle-was traditionally used for lipid metabolism disorders and to sustain liver function. This review describes the major defects of insulin signaling leading to IR and the main properties of the three mentioned natural substances, their molecular targets and synergistic action mechanisms. The actions of berberine, quercetin and silymarin are partially superimposable as remedies against reactive oxygen intermediates generated by a high-lipid diet and by NADPH oxidase, which is triggered by phagocyte activation. Furthermore, these compounds inhibit the secretion of a battery of pro-inflammatory cytokines, modulate intestinal microbiota and are especially able to control the various disorders of the insulin receptor and post-receptor signaling systems. Although most of the evidence on the effects of berberine, quercetin and silymarin in modulating insulin resistance and preventing cardiovascular disease derive from experimental studies on animals, the amount of pre-clinical knowledge strongly suggests the need to investigate the therapeutic potential of these substances in human pathology.

The Epigenetic Regulation of RNA N6-Methyladenosine Methylation in Glycolipid Metabolism

The highly conserved and dynamically reversible N6-methyladenine (m6A) modification has emerged as a critical gene expression regulator by affecting RNA splicing, translation efficiency, and stability at the post-transcriptional level, which has been established to be involved in various physiological and pathological processes, including glycolipid metabolism and the development of glycolipid metabolic disease (GLMD). Hence, accumulating studies have focused on the effects and regulatory mechanisms of m6A modification on glucose metabolism, lipid metabolism, and GLMD. This review summarizes the underlying mechanism of how m6A modification regulates glucose and lipid metabolism-related enzymes, transcription factors, and signaling pathways and the advances of m6A regulatory mechanisms in GLMD in order to deepen the understanding of the association of m6A modification with glycolipid metabolism and GLMD.