The response of gut microbiota to arsenic metabolism is involved in arsenic-induced liver injury, which is influenced by the interaction between arsenic and methionine synthase.

The drivers of changes in gut microbiota under arsenic exposure and the mechanism by which microbiota affect arsenic metabolism are still unclear. Here, C57BL/6 mice were exposed to 0, 5, or 10 ppm NaAsO2 in drinking water for 6 months. The results showed that arsenic exposure induced liver injury and increased the abundance of folic acid (FA)/vitamin B12 (VB12)- and butyrate-synthesizing microbiota. Statistical analysis and in vitro cultures showed that microbiota were altered to meet the demand for FA/VB12 by arsenic metabolism and to resist the toxicity of unmetabolized arsenic. However, at higher arsenic levels, changes of these microbiota were inconsistent. A 3D molecular simulation showed that arsenic bound to methionine synthase (MTR), which was confirmed by SEC-UV-DAD (1 µM recombinant human MTR was purified with 0 or 2 µM NaAsO2 at room temperature for 1 h) and fluorescence-labeled arsenic co-localization (primary hepatocytes were exposed to 0, 0.5, or 1 µM ReAsH-EDT2 for 24 h) in non-cellular and cellular systems. Mechanistically, the arsenic-MTR interaction in the liver interferes with the utilization of FA/VB12, which increases arsenic retention and thus results in a substantial increase in the abundance of butyrate-synthesizing microbiota compared to FA/VB12-synthesizing microbiota. By exposing C57BL/6J mice to 0 or 10 ppm NaAsO2 with or without FA (6 mg/L) and VB12 (50 µg/L) supplementation in their drinking water for 6 months, we constructed an FA/VB12 intervention mouse model and found that FA/VB12 supplementation blocked the disturbance of gut microbiota, restored MTR levels, promoted arsenic metabolism, and alleviated liver injury. We demonstrate that the change of gut microbiota is a response to arsenic metabolism, a process influenced by the arsenic-MTR interaction. This study provides new insights for understanding the relationship between gut microbiota and arsenic metabolism and present therapeutic targets for arseniasis.

miR-21-Mediated Endothelial Senescence and Dysfunction Are Involved in Cigarette Smoke-Induced Pulmonary Hypertension through Activation of PI3K/AKT/mTOR Signaling.

Smoking is a pathogenic factor for pulmonary hypertension (PH). Our previous study showed that serum miR-21 levels are elevated in smokers. miR-21 is considered as engaged in the PH process; however, its mechanisms remain unclear. In this investigation, we found that in the lung tissue of smoking-induced PH patients, the levels of miR-21 and aging markers (p21 and p16) were upregulated, and the function of pulmonary vascular endothelial cells was also impaired. Exposure of mice to cigarette smoke (CS) for four months caused similar changes in lung tissues and increased pulmonary arterial pressure, which were attenuated by knockout of miR-21. Further, human umbilical vein endothelial cells (HUVECs) exposed to cigarette smoke extract (CSE) revealed upregulation of miR-21 levels, depression of PTEN, activation of PI3K/AKT/mTOR signaling, an increase in senescence indexes, and enhanced dysfunction. Inhibiting miR-21 overexpression reversed the PTEN-mTOR signaling pathway and prevented senescence and dysfunction of HUVECs. In sum, our data indicate that miR-21-mediated endothelial senescence and dysfunction are involved in CS-induced PH through the activation of PI3K/AKT/mTOR signaling, which suggests that selective miR-21 inhibition offers the potential to attenuate PH.

circADAMTS6 via stabilizing CAMK2A is involved in smoking-induced emphysema through driving M2 macrophage polarization.

Cigarette smoke (CS), an indoor environmental pollutant, is a prominent risk factor for emphysema, which is a pathological feature of chronic obstructive pulmonary disease (COPD). Emerging function of circRNAs in immune responses and disease progression shed new light to explore the pathogenesis of emphysema. In this research, we demonstrated, by single-cell RNA sequencing (scRNAseq), that the ratio of M2 macrophages were increased in lung tissues of humans and mice with smoking-related emphysema. Further, our data showed that circADAMTS6 was associated with cigarette smoke extract (CSE)-induced M2 macrophage polarization. Mechanistically, in macrophages, circADAMTS6 stabilized CAMK2A mRNA via forming a circADAMTS6/IGF2BP2/CAMK2A RNA-protein ternary complex to activate CREB, which drives M2 macrophage polarization and leads to emphysema. In addition, in macrophages of mouse lung tissues, downregulation of circADAMTS6 reversed M2 macrophage polarization, the proteinase/anti-proteinase imbalance, and the elastin degradation, which protecting against CS-induced emphysema. Moreover, for macrophages and in a model with co-cultured lung organoids, the target of circADAMTS6 restored the growth of lung organoids compared to CSE-treated macrophages. Our results also demonstrated that, for smokers and COPD smokers, elevation of circADAMTS6 negatively correlated with lung function. Overall, this study reveals a novel mechanism for circADAMTS6-driven M2 macrophage polarization in smoking-related emphysema and postulates that circADAMTS6 could serve as a diagnostic and therapeutic marker for smoking-related emphysema.

Highly Stable Amorphous (Pyro)phosphate Aggregates: Pyrophosphate as a Carrier for Bioactive Ions and Drugs in Bone Repair Applications.

Pyrophosphate is widely used as an iron supplement because of its excellent complexation and hydrolysis ability; however, there are few reports on the use of pyrophosphate in active ionophores for bone repair. In this research, we proposed a simple and efficient ultrasonic method to prepare magnesium-calcium (pyro)phosphate aggregates (AMCPs). Due to strong hydration, AMCPs maintain a stable amorphous form even at high temperatures (400 °C). By changing the molar ratio of calcium and magnesium ions, the content of calcium and magnesium ions can be customized. AMCPs had surface negativity and complexing ability that realized the controlled release of ions (Ca2+, Mg2+, and P) and drugs (such as doxorubicin) over a long period. Pyrophosphate gave it an excellent bacteriostatic effect. Increasingly released Mg2+ exhibited improved bioactivity though the content of Ca2+ decreased. While Mg2+ content was regulated to 15 wt %, it performed significantly enhanced stimulation on the proliferation, attachment, and differentiation (ALP activity, calcium nodules, and the related gene expression of osteogenesis) of mouse embryo osteoblast precursor cells (MC3T3-E1). Furthermore, the high content of Mg2+ also effectively promoted the proliferation, attachment, and migration of human umbilical vein endothelial cells (HUVECs) and the expression of angiogenic genes. In conclusion, pyrophosphate was an excellent carrier for bioactive ions, and the AMCPs we prepared had a variety of active functions for multiscenario bone repair applications.

Urea cycle promotion via ammonia-upregulated CPS1 is involved in arsenite-induced pulmonary fibrosis through enhancing collagen synthesis.

Arsenic exposure is connected with lung toxicity and is related to lung fibrotic changes. Idiopathic pulmonary fibrosis (IPF) is characterized by extracellular matrix (ECM) deposition. Various genetic mechanisms and environmental factors induce or exacerbate pulmonary fibrosis. Collagen synthesis induced by sodium arsenite (NaAsO2) is closely associated with IPF. Fibroblasts tend to fine-tune their metabolic networks to support their synthetic requirements in response to environmental stimuli. Alterations in metabolism have an influential role in the pathogenesis of IPF. However, it is unclear how arsenic affects the metabolism in IPF. The urea cycle (UC) is needed for collagen formation, which provides adequate levels of proline (Pro) for biosynthesis of collagen. Carbamoyl phosphate synthetase 1 (CPS1) converts the ammonia to carbamoyl phosphate, which controls the first reaction of the UC. We show that, in arsenite-exposed mice, high amounts of ammonia in the lung microenvironment promotes the expression levels of CPS1 and the Pro metabolism. Reduction of ammonia and CPS1 ablation inhibit collagen synthesis and ameliorate IPF phenotypes induced by arsenite. This work takes advantage of multi-omics data to enhance understanding of the underlying pathogenic mechanisms, the key molecules and the complicated cellular responses to this pollutant, which provide a target for the prevention of pulmonary fibrosis caused by arsenic.

Stenotrophomonas maltophilia contributes to smoking-related emphysema through IRF1-triggered PANoptosis of alveolar epithelial cells.

Cigarette smoke (CS), the main source of indoor air pollution and the primary risk factor for respiratory diseases, contains chemicals that can perturb microbiota through antibiotic effects. Although smoking induces a disturbance of microbiota in the lower respiratory tract, whether and how it contributes to initiation or promotion of emphysema are not well clarified. Here, we demonstrated an aberrant microbiome in lung tissue of patients with smoking-related COPD. We found that Stenotrophomonas maltophilia (S. maltophilia) was expanded in lung tissue of patients with smoking-related COPD. We revealed that S. maltophilia drives PANoptosis in alveolar epithelial cells and represses formation of alveolar organoids through IRF1 (interferon regulatory factor 1). Mechanistically, IRF1 accelerated transcription of ZBP1 (Z-DNA Binding Protein 1) in S. maltophilia-infected alveolar epithelial cells. Elevated ZBP1 served as a component of the PANoptosome, which triggered PANoptosis in these cells. By using of alveolar organoids infected by S. maltophilia, we found that targeting of IRF1 mitigated S. maltophilia-induced injury of these organoids. Moreover, the expansion of S. maltophilia and the expression of IRF1 negatively correlated with the progression of emphysema. Thus, the present study provides insights into the mechanism of lung dysbiosis in smoking-related COPD, and presents a potential target for mitigation of COPD progression.

Decreased Ubiquitination and Acetylation of Histones 3 and 4 Are Associated with Obesity-Induced Disorders of Spermatogenesis in Mice.

BACKGROUND: Obesity, a chronic metabolic disorder, is related to cardiovascular diseases, diabetes, cancer, and reproductive disorders. The relationship between obesity and male infertility is now well recognized, but the mechanisms involved are unclear. We aimed to observe the effect of obesity on spermatogenesis and to investigate the role of histone ubiquitination and acetylation modifications in obesity-induced spermatogenesis disorders. METHODS: Thirty male C57BL/6J mice were randomly divided into two groups. The control group was fed with a general maintenance diet (12% fat), while a high-fat diet (HFD) group was fed with 40% fat for 10 weeks; then, they were mated with normal females. The fertility of male mice was calculated, testicular and sperm morphology were observed, and the expression levels of key genes and the levels of histone acetylation and ubiquitination modification during spermatogenesis were detected. RESULTS: The number of sperm was decreased, as well as the sperm motility, while the number of sperm with malformations was increased. In the testes, the mRNA and protein expression levels of gonadotropin-regulated testicular RNA helicase (GRTH/DDX25), chromosome region maintenance-1 protein (CRM1), high-mobility group B2 (HMGB2), phosphoglycerate kinase 2 (PGK2), and testicular angiotensin-converting enzyme (tACE) were decreased. Furthermore, obesity led to a decrease in ubiquitinated H2A (ubH2A) and reduced levels of histone H3 acetylation K18 (H3AcK18) and histone H4 acetylation K5, K8, K12, and K16 (H4tetraAck), which disrupted protamine 1 (Prm1) deposition in testis tissue. CONCLUSION: These results suggest that low levels of histone ubiquitination and acetylation are linked with obesity-induced disorders during spermatogenesis, contributing to a better understanding of obesity-induced damage to male reproduction.

NSUN2 promotes lung adenocarcinoma progression through stabilizing PIK3R2 mRNA in an m5C-dependent manner.

It is well known that 5-methylcytosine (m5C) is involved in variety of crucial biological processes in cancers. However, its biological roles in lung adenocarcinoma (LAUD) remain to be determined. The LUAD samples were used to assess the clinical value of NOP2/Sun RNA Methyltransferase 2 (NSUN2). Dot blot was used to determine global m5C levels. ChIP and dual-luciferase assays were performed to investigate the MYC-associated zinc finger protein (MAZ)-binding sites in NSUN2 promoter. RNA-seq was used to explore the downstream molecular mechanisms of NSUN2. Dual luciferase reporter assay, m5C-RIP-qPCR, and mRNA stability assay were conducted to explore the effect of NSUN2-depletion on target genes. Cell viability, transwell, and xenograft mouse model were designed to demonstrate the characteristic of NSUN2 in promoting LUAD progression. The m5C methyltransferase NSUN2 was highly expressed and caused elevated m5C methylation in LUAD samples. Mechanistically, MAZ positively regulated the transcription of NSUN2 and was related to poor survival of LUAD patients. Silencing NSUN2 decreased the global m5C levels, suppressed proliferation, migration and invasion, and inhibited activation of PI3K-AKT signaling in A549 and SPAC-1 cells. Phosphoinositide-3-Kinase Regulatory Subunit 2 (PIK3R2) was upregulated by NSUN2-mediated m5C methylation by enhancing its mRNA stabilization and activated the phosphorylation of the PI3K-AKT signaling. The present study explored the underlying mechanism and biological function of NSUN2-meditated m5C RNA methylation in LUAD. NSUN2 was discovered to facilitate the malignancy progression of LUAD through regulating m5C modifications to stabilize PIK3R2 activating the PI3K-AKT signaling, suggesting that NSUN2 could be a novel biomarker and promising therapeutic target for LUAD patients.

Human CYP1A1-activated aneugenicity of aflatoxin B1 in mammalian cells and its combined effect with benzo(a)pyrene.

Aflatoxin B1 (AFB1) is the most toxic mycotoxin and a proven human carcinogen that requires metabolic activation, known by cytochrome P450 (CYP) 1A2 and 3A4. Previous evidence showed that AFB1 is activated by human recombinant CYP1A1 expressed in budding yeast. Yet, the toxicity, in particular the genotoxicity of the reactive metabolites formed from AFB1 remains unclear. Humans could be exposed to both AFB1 and benzo(a)pyrene (BaP) simultaneously, thus we were interested in their combined genotoxic effects subsequent to metabolic activation by CYP1A1. In this study, molecular docking of AFB1 to human CYP1A1 indicated that AFB1 is valid as a substrate. In the incubations with AFB1 in human CYP1A1-expressed microsomes, AFM1 as a marking metabolite of AFB1 was detected. Moreover, AFB1 induced micronucleus formation in a Chinese hamster V79-derived cell line and in a human lung epithelial BEAS-2B cell line, both expressing recombinant human CYP1A1, V79-hCYP1A1 and 2B-hCYP1A1 cells, respectively. Immunofluorescence of centromere protein B stained micronuclei was dominant in AFB1-treated BEAS-2B cells exposed to AFB1, suggesting an aneugenic effect. Moreover, AFB1 elevated the levels of ROS, 8-OHdG, AFB1-DNA adduct, and DNA breaks in 2B-hCYP1A1 cells, compared with those in the parental BEAS-2B cells. Meanwhile, AFB1 increased CYP1A1, RAD51, and γ-H2AX protein levels in 2B-hCYP1A1 cells, which were attenuated by the CYP1A1 inhibitor bergamottin. Co-exposure of AFB1 with BaP increased 8-OHdG, RAD51, and γ-H2AX levels (indicating DNA damage). In conclusion, AFB1 could be activated by human CYP1A1 for potent aneugenicity, which may be further enhanced by co-exposure to BaP.

Intrauterine arsenic exposure induces glucose metabolism disorders in adult offspring by targeting TET2-mediated DNA hydroxymethylation reprogramming of HNF4α in developing livers, an effect alleviated by ascorbic acid.

Exposure to arsenic during gestation has lasting health-related effects on the developing fetus, including an increase in the risk of metabolic disease later in life. Epigenetics is a potential mechanism involved in this process. Ten-eleven translocation 2 (TET2) has been widely considered as a transferase of 5-hydroxymethylcytosine (5hmC). Here, mice were exposed, via drinking water, to arsenic or arsenic combined with ascorbic acid (AA) during gestation. For adult offspring, intrauterine arsenic exposure exhibited disorders of glucose metabolism, which are associated with DNA hydroxymethylation reprogramming of hepatic nuclear factor 4 alpha (HNF4α). Further molecular structure analysis, by SEC-UV-DAD, SEC-ICP-MS, verified that arsenic binds to the cysteine domain of TET2. Mechanistically, arsenic reduces the stability of TET2 by binding to it, resulting in the decrease of 5hmC levels in Hnf4α and subsequently inhibiting its expression. This leads to the disorders of expression of its downstream key glucose metabolism genes. Supplementation with AA blocked the reduction of TET2 and normalized the 5hmC levels of Hnf4α, thus alleviating the glucose metabolism disorders. Our study provides targets and methods for the prevention of offspring glucose metabolism abnormalities caused by intrauterine arsenic exposure.

TXNIP-NLRP3-GSDMD axis-mediated inflammation and pyroptosis of islet ß-cells is involved in cigarette smoke-induced hyperglycemia, which is alleviated by andrographolide.

Epidemiologic surveys have indicated that cigarette smoking is an important risk factor for diabetes, but its mechanisms remain unclear. Andrographolide, an herb traditionally utilized in medicine, provides anti-inflammatory benefits for various diseases. In the present work, 265 patients with Type 2 diabetes (T2D) were investigated, and male C57BL/6 mice were exposed to cigareete smoke (CS) and/or to intraperitoneally injected andrographolide for 3 months. To elucidate the mechanism of CS-induced hyperglycemia and the protective mechanism of andrographolide, MIN6 cells were exposed to cigarette smoke extract (CSE) and/or to andrographolide. Our data from 265 patients with T2D showed that urinary creatinine and serum inflammatory cytokines (interleukin 6 (IL-6), IL-8, IL-1ß, and tumor necrosis factor α (TNF-α)) increased with smoking pack-years. In a mouse model, CS induced hyperglycemia, decreased insulin secretion, and elevated inflammation and pyroptosis in ß-cells of mice. Treatment of mice with andrographolide preserved pancreatic function by reducing the expression of inflammatory cytokines; the expression of TXNIP, NLRP3, cleaved caspase 1, IL-1ß; and the N-terminal of gasdermin D (GSDMD) protein. For MIN6 cells, CSE caused increasing secretion of the inflammatory cytokines IL-6 and IL-1ß, and the expression of TXNIP and pyroptosis-related proteins; however, andrographolide alleviated these changes. Furthermore, silencing of TXNIP showed that the blocking effect of andrographolide may be mediated by TXNIP. In sum, our results indicate that CS induces hyperglycemia through TXNIP-NLRP3-GSDMD axis-mediated inflammation and pyroptosis of islet ß-cells and that andrographolide is a potential therapeutic agent for CS-induced hyperglycemia.

Construction of an adverse outcome pathway framework based on integrated data to evaluate arsenic-induced non-alcoholic fatty liver disease.

Arsenic is a recognized environmental pollutant naturally occurring in aquifers through geological processes. Toxicological studies have revealed that liver is the main target organ harmed by arsenic exposure. However, systematic studies of non-alcoholic fatty liver disease (NAFLD) are not comprehensive, and information regarding threats and risk assessment remains insufficient. This research aimed to examine the association between arsenic exposure and NAFLD and uncover the role of molecular initiating events and key events in disease development using the Adverse Outcome Pathway (AOP). Data from 8,104 adults in the National Health and Nutrition Examination Survey were used to explore the relationship between urinary arsenic and NAFLD. In a logistic regression model, urinary inorganic arsenic levels positively correlated with NAFLD (odds ratio = 1.12, 95 % confidence interval = 1.07-1.16). Subsequently, to gain a deeper understanding of arsenic-induced NAFLD, an AOP framework was constructed, revealing that arsenic exposure led to elevate levels of TNF-α, which regulated the NF-κB pathway and led to hepatic lipid deposition, causing NAFLD. This AOP was assessed as "high" according to the Organization for Economic Co-operation and Development users' handbook, and in vitro and in vivo models validated the AOP framework. In summary, this study highlights the potential mechanisms of arsenic-induced NAFLD. We combined the AOP with classical toxicological approaches with a view of establishing, rapidly and accurately, the lowest level at which environmental arsenic exposure can have adverse effects on the body, thereby contributing to risk assessment strategies for arsenic exposure through iterative and animal modeling at the population level.

miR-153-3p via PIK3R1 Is Involved in Cigarette Smoke-Induced Neurotoxicity in the Brain.

Cigarettes contain various chemicals that cause damage to nerve cells. Exposure to cigarette smoke (CS) causes insulin resistance (IR) in nerve cells. However, the mechanisms for a disorder in the cigarette-induced insulin signaling pathway and in neurotoxicity remain unclear. Therefore, we evaluated, by a series of pathology analyses and behavioral tests, the neurotoxic effects of chronic exposure to CS on C57BL/6 mice. Mice exposed to CS with more than 200 mg/m3 total particulate matter (TPM) exhibited memory deficits and cognitive impairment. Pathological staining of paraffin sections of mouse brain tissue revealed that CS-exposed mice had, in the brain, neuronal damage characterized by thinner pyramidal and granular cell layers and fewer neurons. Further, the exposure of SH-SY5Y cells to cigarette smoke extract (CSE) resulted in diminished insulin sensitivity and reduced glucose uptake in a dose-dependent fashion. The PI3K/GSK3 insulin signaling pathway is particularly relevant to neurotoxicity. microRNAs are involved in the PI3K/GSK3ß/p-Tau pathway, and we found that cigarette exposure activates miR-153-3p, decreases PI3K regulatory subunits PIK3R1, and induces Tau hyperphosphorylation. Exposure to an miR-153 inhibitor or to a PI3K inhibitor alleviated the reduced insulin sensitivity caused by CS. Therefore, our results indicate that miR-153-3p, via PIK3R1, causes insulin resistance in the brain, and is involved in CS-induced neurotoxicity.

Retraction Notice to: METTL3-mediated m6A modification of ZBTB4 mRNA is involved in the smoking-induced EMT in cancer of the lung.

[This retracts the article DOI: 10.1016/j.omtn.2020.12.001.].

The lncRNA H19/miR-29a-3p/SNIP1/c-myc regulatory axis is involved in pulmonary fibrosis induced by Nd2O3.

Some rare earth elements are occupational and environmental toxicants and can cause organ and systemic damage; therefore, they have attracted global attention. Neodymium oxide (Nd2O3) is a rare earth element that is refined and significantly utilized in China. The long noncoding RNA (lncRNA) H19 is encoded by the H19/IGF2 imprinted gene cluster located on human chromosome 11p15.5. H19 has become a research focus due to its ectopic expression leading to the promotion of fibrosis. However, the mechanisms by which it causes pulmonary fibrosis are elusive. This investigation indicates that biologically active Nd2O3 increases H19, SNIP1, and c-myc, decreases miR-29a-3p, accelerates macrophage M2 polarization, and causes pulmonary fibrosis in mice lung tissues. In macrophage-differentiated THP-1 cells, Nd2O3 (25 µg/ml) enhanced H19, SNIP1, and c-myc, reduced miR-29a-3p, accelerated macrophages M2 polarization, and stimulated fibrogenic cytokine (TGF-ß1) secretion. Furthermore, the coculturing of Nd2O3-treated macrophage-differentiated THP-1 cells. And human embryonic lung fibroblast cells activated lung fibroblast, which increases the levels of collagen I, α-SMA, p-Smad2/3, and Smad4, whereas H19 knockdown or miR-29a-3p upregulation in macrophages had opposite effects. Moreover, it was revealed that H19/miR-29a-3p/SNIP1/c-myc regulatory axis is involved in pulmonary fibrosis induced by Nd2O3. Therefore, this study provides new molecular insights into the mechanism of pulmonary fibrosis by Nd2O3.

Non-coding RNA therapeutics: Towards a new candidate for arsenic-induced liver disease.

Arsenic, a metalloid toxicant, has caused serious environmental pollution and is presently a global health issue. Long-term exposure to arsenic causes diverse organ and system dysfunctions, including liver disease. Arsenic-induced liver disease comprises a spectrum of liver pathologies, ranging from hepatocyte damage, steatosis, fibrosis, to hepatocellular carcinoma. Various mechanisms, including an imbalance in redox reactions, mitochondrial dysfunction and epigenetic changes, participate in the pathogenesis of arsenic-induced liver disease. Altered epigenetic processes involved in its initiation and progression. Dysregulated modulations of non-coding RNAs (ncRNAs), including miRNAs, lncRNAs and circRNAs, exert regulating effects on these processes. Here, we have reviewed the underlying pathogenic mechanisms that lead to progressive arsenic-induced liver disease, and we provide a discussion focusing on the effects of ncRNAs on dysfunctions in intercellular communication and on the activation of hepatic stellate cells and malignant transformation of hepatocytes. Further, we have discussed the roles of ncRNAs in intercellular communication via extracellular vesicles and cytokines, and have provided a perspective for the application of ncRNAs as biomarkers in the early diagnosis and evaluation of the pathogenesis of arsenic-induced liver disease. Further investigations of ncRNAs will help us to understand the nature of arsenic-induced liver disease and to identify biomarkers and therapeutic targets.

As3MT via consuming SAM is involved in arsenic-induced nonalcoholic fatty liver disease by blocking m6A-mediated miR-142-5p maturation.

Arsenic, a common environmental hazard, is a risk factor for nonalcoholic fatty liver disease (NAFLD). However, the mechanism remains unclear. Here, we found that chronic exposure to environmental-related doses of arsenic disturbed fatty acid and methionine metabolism in mice, caused liver steatosis, increased arsenic (3) methyltransferase (As3MT), sterol regulatory element binding protein 1 (SREBP1) and lipogenic gene levels, and decreased N6-methyladenosine (m6A) and S-adenosylmethionine (SAM) levels. Mechanistically, arsenic blocks m6A-mediated miR-142-5p maturation by consuming SAM via As3MT. miR-142-5p was involved in arsenic-induced cellular lipid accumulation by targeting SREBP1. SAM supplementation or As3MT deficiency blocked arsenic-induced lipid accumulation by promoting the maturation of miR-142-5p. Moreover, in mice, folic acid (FA) and vitamin B12 (VB12) supplementation blocked arsenic-induced lipid accumulation by restoring SAM levels. Arsenic-exposed heterozygous As3MT mice showed low liver lipid accumulation. Our study demonstrates that SAM consumption caused by arsenic, through As3MT, blocks m6A-mediated miR-142-5p maturation, thereby elevating the levels of SREBP1 and lipogenic genes, leading to NAFLD, which provides a new mechanism and biological insights into the therapy of NAFLD induced by environmental factors.

Cigarette smoking, by accelerating the cell cycle, promotes the progression of non-small cell lung cancer through an HIF-1α-METTL3-m6A/CDK2AP2 axis.

Cigarette smoking killed about 8 million people every year and promoted non-small cell lung cancer (NSCLC). We investigated the molecular mechanism of smoking-promoted NSCLC progression. Relative to non-smokers, NSCLC patients who were smokers had a higher tumor malignancy. For NSCLC cells, cigarette smoke extract (CSE) increased levels of HIF-1α, METTL3, Cyclin E1, and CDK2 and promoted the G1/S transition, which promoted cell proliferation. Down-regulation HIF-1α or METTL3 reversed these effects. meRIP-seq and RNA-seq revealed the m6A modification in Cyclin Dependent Kinase 2 Associated Protein 2 (CDK2AP2) mRNA as the key downstream target. Further, for NSCLC cells exposed to CSE, HIF-1α activated METTL3 transcription. Xenografts in nude mice demonstrated that HIF-1α via METTL3 participated in tumor growth. In NSCLC tissues of smokers, protein levels of HIF-1α and METTL3 were higher, and levels of CDK2AP2 were lower. In conclusion, HIF-1α via METTL3 regulation of the m6A modification of CDK2AP2 mRNA drives smoking-induced progression of NSCLC through promoting cell proliferation. This is a previously unknown molecular mechanism for smoking-induced NSCLC progression. The results have potential value for treatment of NSCLC, especially for patients who smoke.

Smoking-Induced M2-TAMs, via circEML4 in EVs, Promote the Progression of NSCLC through ALKBH5-Regulated m6A Modification of SOCS2 in NSCLC Cells.

Lung cancer is a commonly diagnosed disease worldwide, with non-small cell lung cancers (NSCLCs) accounting for ≈ 85% of cases. Cigarette smoke is an environmental exposure promoting progression of NSCLC, but its role is poorly understood. This study reports that smoking-induced accumulation of M2-type tumor-associated macrophages (M2-TAMs) surrounding NSCLC tissues promotes malignancy. Specifically, extracellular vesicles (EVs) from cigarette smoke extract (CSE)-induced M2 macrophages promoted malignancy of NSCLC cells in vitro and in vivo. circEML4 in EVs from CSE-induced M2 macrophages is transported to NSCLC cells, where it reduced the distribution of ALKBH5 in the nucleus by interacting with Human AlkB homolog H5 (ALKBH5), resulting in elevated N6-methyladenosine (m6A) modifications. m6A-seq and RNA-seq revealed suppressor of cytokine signaling 2 (SOCS2)-mediated activation of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway by regulating m6A modification of SOCS2 via ALKBH5. Down-regulation of circEML4 in EVs from CSE-induced M2 macrophages reversed EVs-enhanced tumorigenicity and metastasis in NSCLC cells. Furthermore, this study found that smoking patients showed an increase in circEML4-positive M2-TAMs. These results indicate that smoking-induced M2-TAMs via circEML4 in EVs promote the NSCLC progression through ALKBH5-regulated m6A modification of SOCS2. This study also reveals that circEML4 in EVs from TAMs acts as a diagnostic biomarker for NSCLC, especially for patients with smoking history.