Adipogenic Effects of Cresyl Diphenyl Phosphate (Triphenyl Phosphate Alternative) through Peroxisome Proliferator-Activated Receptor Gamma Pathway: A Comprehensive Study Integrating In Vitro, In Vivo, and In Silico from Molecule to Health Risk.

Cresyl diphenyl phosphate (CDP), a novel organophosphate ester (OPE), has been detected in various environmental and human samples. However, there is very limited knowledge regarding its toxicity, mechanisms of action, and potential health risks. Using new alternative methods (NAMs), across the molecular interactions, signaling pathways, cell functions, animal effects, and population risks, we investigated the potential adipogenic effects and associated risks of CDP and legacy OPE triphenyl phosphate (TPHP) by acting on peroxisome proliferator-activated receptor gamma (PPARγ). Among the 19 screened OPEs, CDP bound to PPARγ with the highest binding potency, followed by TPHP. CDP activated PPARγ through fitting into the binding pocket with strong hydrophobicity and hydrogen bond interactions; CDP exhibited higher potency compared to TPHP. In 3T3-L1 cells, CDP enhanced the PPARγ-mediated adipogenesis activity, exhibiting greater potency than TPHP. The intracellular concentration and receptor-bound concentrations (RBC) of CDP were also higher than those of TPHP in both HEK293 cells and 3T3-L1 cells. In mice, exposure to CDP activated the PPARγ-mediated adipogenic pathway, leading to an increased white adipose tissue weight gain. Overall, CDP could bind to and activate PPARγ, thereby promoting preadipocyte differentiation and the development of white adipose tissue. Its potential obesogenic risks should be of high concern.

Ultrasensitive detection of circulating tumor DNA using a CRISPR/Cas9 nickase-driven 3D DNA walker based on a COF-AuNPs sensing platform.

A electrochemical biosensor was designed utilizing a CRISPR Cas9n-driven DNA walker combined with gold-nanosphere-like covalent organic frameworks (COFs-AuNPs) to detect breast cancer markers (PIK3CA E545K ctDNA). The DNA walker probe is activated only in the presence of circulating tumor deoxyribonucleic acid (ctDNA), binding to a support probe to form a double strand that is then specifically cleaved by the Cas9n/sgRNA complex. This cleavage produces numerous DNA fragments for signal amplification. The COF-AuNPs as electrode materials facilitate electronic transfer and provide additional active sites for the immobilization of nucleic acid probes. This setup achieves a detection limit of 1.76 aM, demonstrating high sensitivity. Additionally, Cas9n improves the specificity of the sensor, accurately distinguishing a pair of base-mismatched sequences, and reducing the occurrence of false positives. Overall, the sensor exhibits excellent selectivity, reproducibility, and potential for early diagnosis of breast cancer.

Integration of metabolomics and proteomics reveals the underlying hepatotoxic mechanism of perfluorooctane sulfonate (PFOS) and 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA) in primary human hepatocytes.

Perfluorooctane sulfonate (PFOS) and its alternative 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) are ubiquitous in various environmental and human samples. They have been reported to have hepatotoxicity effects, but the potential mechanisms remain unclear. Herein, we integrated metabolomics and proteomics analysis to investigate the altered profiles in metabolite and protein levels in primary human hepatocytes (PHH) exposed to 6:2 Cl-PFESA and PFOS at human exposure relevant concentrations. Our results showed that 6:2 Cl-PFESA exhibited higher perturbation effects on cell viability, metabolome and proteome than PFOS. Integration of metabolomics and proteomics revealed that the alteration of glycerophospholipid metabolism was the critical pathway of 6:2 Cl-PFESA and PFOS-induced lipid metabolism disorder in primary human hepatocytes. Interestingly, 6:2 Cl-PFESA-induced cellular metabolic process disorder was associated with the cellular membrane-bounded signaling pathway, while PFOS was associated with the intracellular transport process. Moreover, the disruption effects of 6:2 Cl-PFESA were also involved in inositol phosphate metabolism and phosphatidylinositol signaling system. Overall, this study provided comprehensive insights into the hepatic lipid toxicity mechanisms of 6:2 Cl-PFESA and PFOS in human primary hepatocytes.

Binding and activity of bisphenol analogues to human peroxisome proliferator-activated receptor ß/δ.

Several studies have indicated metabolic function disruption effects of bisphenol analogues through peroxisome proliferator-activated receptor (PPAR) alpha and gamma pathways. In the present study, we found for the first time that PPARß/δ might be a novel cellular target of bisphenol analogues. By using the fluorescence competitive binding assay, we found seven bisphenol analogues could bind to PPARß/δ directly, among which tetrabromobisphenol A (TBBPA, 18.38-fold) and tetrachlorobisphenol A (TCBPA, 12.06-fold) exhibited stronger binding affinity than bisphenol A (BPA). In PPARß/δ-mediated luciferase reporter gene assay, the seven bisphenol analogues showed transcriptional activity toward PPARß/δ. Bisphenol AF (BPAF), bisphenol F (BPF) and bisphenol B (BPB) even showed higher transcriptional activity than BPA, while TBBPA and TCBPA showed comparable activity with BPA. Moreover, in human liver HL-7702 cells, the bisphenol analogues promoted the expression of two PPARß/δ target genes PDK4 and ANGPTL4. Molecular docking simulation indicated the binding potency of bisphenol analogues to PPARß/δ might depend on halogenation and hydrophobicity and the transcriptional activity might depend on their binding affinity and hydrogen bond interactions. Overall, the PPARß/δ pathway may provide a new mechanism for the metabolic function disruption of bisphenol analogues, and TBBPA and TCBPA might exert higher metabolic disruption effects than BPA via PPARß/δ pathway.

Lipid metabolism disorders effects of 6:2 chlorinated polyfluorinated ether sulfonate through Hsa-miRNA-532-3p/Acyl-CoA oxidase 1(ACOX1) pathway.

6:2 Chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), an alternative product of perfluorooctane sulfonate (PFOS), has been frequently detected in various environmental, wildlife, and human samples. A few studies revealed the hepatotoxicity of 6:2 Cl-PFESA in animals, but the underlying toxicity mechanisms remain largely unknown. In this study, we investigated the lipid metabolism disorders of 6:2 Cl-PFESA through miRNA-gene interaction mode in Huh-7 cells. Our results showed that 6:2 Cl-PFESA significantly promoted cellular lipid accumulation and increased the expression of Acyl-CoA oxidase 1 (ACOX1), with the lowest effective concentrations (LOECs) of 3 µM. In silico analysis showed that hsa-miR-532-3p is a potential miRNA molecule targeting ACOX1. Fluorescent-based RNA electrophoretic mobility shift assay (FREMSA) and ACOX1-mediated luciferase reporter gene assays showed that hsa-miR-532-3p could directly bind to ACOX1 and inhibit its transcription activity. Besides, 6:2 Cl-PFESA decreased the expression of hsa-miR-532-3p in the PPARα-independent manner. Overexpression of hsa-miR-532-3p promoted 6:2 Cl-PFESA-induced cellular lipid accumulation and decreased the ACOX1 production in Huh-7 cells. Taken together, at human exposure relevant concentrations, 6:2 Cl-PFESA might upregulate the expression levels of ACOX1 through downregulating hsa-miR-532-3p, and disturbed lipid homeostasis in Huh-7 cells, which revealed a novel epigenetic mechanism of 6:2 Cl-PFESA-induced hepatic lipid toxic effects.

MicroRNA hsa-miR-1301-3p Regulates Human ADH6, ALDH5A1 and ALDH8A1 in the Ethanol-Acetaldehyde-Acetate Metabolic Pathway.

Alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs) are vital enzymes involved in the metabolism of a variety of alcohols. Differences in the expression and enzymatic activity of human ADHs and ALDHs correlate with individual variability in metabolizing alcohols and drugs and in the susceptibility to alcoholic liver disease. MicroRNAs (miRNAs) function as epigenetic modulators to regulate the expression of drug-metabolizing enzymes. To characterize miRNAs that target ADHs and ALDHs in human liver cells, we carried out a systematic bioinformatics analysis to analyze free energies of the interaction between miRNAs and their cognate sequences in ADH and ALDH transcripts and then calculated expression correlations between miRNAs and their targeting ADH and ALDH genes using a public data base. Candidate miRNAs were selected to evaluate bioinformatic predictions using a series of biochemical assays. Our results showed that 11 miRNAs have the potential to modulate the expression of two ADH and seven ALDH genes in the human liver. We found that hsa-miR-1301-3p suppressed the expression of ADH6, ALDH5A1, and ALDH8A1 in liver cells and blocked their induction by ethanol. In summary, our results revealed that hsa-miR-1301-3p plays an important role in ethanol metabolism by regulating ADH and ALDH gene expression. SIGNIFICANCE STATEMENT: Systematic bioinformatics analysis showed that 11 microRNAs might play regulatory roles in the expression of two alcohol dehydrogenase (ADH) and seven aldehyde dehydrogenase (ALDH) genes in the human liver. Experimental evidences proved that hsa-miR-1301-3p suppressed the expression of ADH6, ALDH5A1, and ALDH8A1 in liver cells and decreased their inducibility by ethanol.

Receptor-Bound Perfluoroalkyl Carboxylic Acids Dictate Their Activity on Human and Mouse Peroxisome Proliferator-Activated Receptor γ.

In in vitro cell assays, nominal concentrations of a test chemical are most frequently used in the description of its dose-response curves. Although the biologically effective concentration (BEC) is considered as the most relevant dose metric, in practice, it is very difficult to measure. In this work, we attempted to determine the BEC of long-chain perfluoroalkyl carboxylic acids (PFCAs) in peroxisome proliferator-activated receptor γ (PPARγ) activity assays. In both adipogenesis and transcriptional activity assays with human and mouse cells, PPARγ activity of 7 PFCAs first increased and then decreased with their carbon chain length. The binding affinity of these PFCAs with the ligand-binding domain of PPARγ was measured by fluorescence competitive binding assay and showed very poor correlation with their receptor activity (r2 = 0.002-0.047). Internal concentrations of the PFCAs in the cells were measured by LC-MS/MS. Although their correlation with the receptor activity increased significantly, it is still low (r2 = 0.41-0.82). Using the binding affinity constant, internal concentration, and PPARγ concentration measured by immunoassays, concentrations of receptor-bound PFCAs in cells were calculated, which exhibited excellent correlation with PPARγ activity in both adipogenesis and transcriptional activity assays (r2 = 0.91-0.93). These results demonstrate that the concentration of receptor-bound PFCA is the BEC that dictates its activity on human and mouse PPARγ in cell assays. In the absence of any direct detection method, our approach can be used to calculate the target-site concentration of other ligands.

Perfluoroalkyl Substances Stimulate Insulin Secretion by Islet ß Cells via G Protein-Coupled Receptor 40.

The potential causal relationship between exposure to environmental contaminants and diabetes is troubling. Exposure of perfluoroalkyl substances (PFASs) is found to be associated with hyperinsulinemia and the enhancement of insulin secretion by islet ß cells in humans, but the underlying mechanism is still unclear. Here, by combining in vivo studies with both wild type and gene knockout mice and in vitro studies with mouse islet ß cells (ß-TC-6), we demonstrated clearly that 1 h exposure of perfluorooctanesulfonate (PFOS) stimulated insulin secretion and intracellular calcium level by activating G protein-coupled receptor 40 (GPR40), a vital free fatty acid regulated membrane receptor on islet ß cells. We further showed that the observed effects of PFASs on the mouse model may also exist in humans by investigating the molecular binding interaction of PFASs with human GPR40. We thus provided evidence for a novel mechanism for how insulin-secretion is disrupted by PFASs in humans.

Integration of proteomics, lipidomics, and metabolomics reveals novel metabolic mechanisms underlying N, N-dimethylformamide induced hepatotoxicity.

N, N-Dimethylformamide (DMF) is a universal organic solvent which widely used in various industries, and a considerable amount of DMF is detected in industrial effluents. Accumulating animal and epidemiological studies have identified liver injury as an early toxic effect of DMF exposure; however, the detailed mechanisms remain poorly understood. In this study, we systematically integrated the quantitative proteomics, lipidomics, and metabolomics data obtained from the primary human hepatocytes exposed to DMF, to depict the complicated biochemical reactions correlated to liver damage. Eventually, we identified 284 deregulated proteins (221 downregulated and 63 upregulated) and 149 deregulated lipids or metabolites (99 downregulated and 50 upregulated) induced by DMF exposure. Further, the integration of the protein-metabolite (lipid) interactions revealed that N-glycan biosynthesis (involved in the endoplasmic reticulum stress and the unfolded protein response), bile acid metabolism (involved in the lipid metabolism and the inflammatory process), and mitochondrial dysfunction and glutathione depletion (both contributed to reactive oxygen species) were the typical biochemical reactions disturbed by DMF exposure. In summary, our study identified the versatile protein, lipid, and metabolite molecules in multiple signaling and metabolic pathways involved in DMF induced liver injury, and provided new insights to elucidate the toxic mechanisms of DMF.

Adipogenic Activity of Oligomeric Hexafluoropropylene Oxide (Perfluorooctanoic Acid Alternative) through Peroxisome Proliferator-Activated Receptor γ Pathway.

Hexafluoropropylene oxide trimer acid (HFPO-TA) and hexafluoropropylene oxide dimer acid (HFPO-DA) have been used as perfluorooctanoic acid (PFOA) alternatives in the fluoropolymer industry for years. Their widespread environmental distribution, high bioaccumulation capability, and human exposure have caused great concern. Nevertheless, their potential toxicity and health risk remain largely unknown. In the present study, we compared potential disruption effects of HFPO-TA, HFPO-DA, and PFOA on peroxisome proliferator-activated receptor γ (PPARγ) via the investigation of receptor binding, receptor activity, and cell adipogenesis effects. The receptor binding experiment showed HFPO-TA exhibited 4.8-7.5 folds higher binding affinity with PPARγ than PFOA, whereas HFPO-DA exhibited weaker binding affinity than PFOA. They also showed agonistic activity toward PPARγ signaling pathway in HEK 293 cells in the order of HFPO-TA > PFOA > HFPO-DA. Molecular docking simulation indicated HFPO-TA formed more hydrogen bonds than PFOA, whereas HFPO-DA formed fewer hydrogen bonds than PFOA. HFPO-TA promoted adipogenic differentiation and lipid accumulation in both mouse and human preadipocytes with potency higher than PFOA. Adipogenesis in human preadipocytes is a more sensitive end point than mouse preadipocytes. Collectively, HFPO-TA exerts higher binding affinity, agonistic activity, and adipogenesis activity than PFOA. The potential health risk of HFPO-TA should be of concern.

Binding and activity of sulfated metabolites of lower-chlorinated polychlorinated biphenyls towards thyroid hormone receptor alpha.

There has been long-standing evidence that the lower-chlorinated polychlorinated biphenyls (LC-PCBs) can be metabolized to hydroxylated metabolites (OH-PCBs), which play important roles in the LC-PCBs induced toxicity. Recently, multiple studies have demonstrated the further metabolic transformation of OH-PCBs to LC-PCB sulfates in vitro and in vivo. Several studies found LC-PCB sulfates could bind with thyroid hormone (TH) transport proteins in the serum, indicating the potential relevance of these metabolites in the TH system disruption effects. However, the interaction of LC-PCB sulfates with the TH nuclear receptor (TR), another kind of important functional protein in the TH system, has not been explored. Here, by using a fluorescence competitive binding assay, we demonstrated that LC-PCB sulfates could bind with TRα. Moreover, the LC-PCB sulfates had higher binding potency than their corresponding OH-PCB precursors. By using a luciferase reporter gene assay, we found the LC-PCB sulfates showed agonistic activity towards the TRα signaling pathway. Molecular docking simulation showed all the tested LC-PCB sulfates could fit into the ligand binding pocket of the TRα. The LC-PCB sulfates formed hydrogen bond interaction with arginine 228 residue of TRα by their sulfate groups, which might facilitate the TR binding and agonistic activity. The present study suggests that interaction with the TR might be another possible mechanism by which LC-PCB sulfate induce TH system disruption effects.

Chlorinated Polyfluoroalkylether Sulfonates Exhibit Similar Binding Potency and Activity to Thyroid Hormone Transport Proteins and Nuclear Receptors as Perfluorooctanesulfonate.

Chlorinated polyfluoroalkylether sulfonates (Cl-PFAESs) have been used as perfluorooctanesulfonate (PFOS) alternatives in the chrome plating industry for years. Although Cl-PFAESs have become ubiquitous environmental contaminants, knowledge on their toxicological mechanism remains very limited. We compared potential thyroid hormone (TH) disruption effects of Cl-PFAESs and PFOS via the mechanisms of competitive binding to TH transport proteins and activation of TH receptors (TRs). Fluorescence binding assays revealed that 6:2 Cl-PFAES, 8:2 Cl-PFAES and F-53B (a mixture of 6:2 and 8:2 Cl-PFAES) all interacted with a TH transport protein transthyretin (TTR), with 6:2 Cl-PFAES showing the highest affinity. It was also found that the chemicals interacted with TRs, with the affinity following the order of 6:2 Cl-PFAES > PFOS > 8:2 Cl-PFAES. In reporter gene assays the chemicals exhibited agonistic activity toward TRs, with the potency of 6:2 Cl-PFAES comparable to that of PFOS. The chemicals also promoted GH3 cell proliferation, with 6:2 Cl-PFAES displaying the highest potency. Molecular docking and molecular dynamic simulation revealed that both Cl-PFAESs fit into the ligand binding pockets of TTR and TRs with the binding modes similar to PFOS. Collectively, our results demonstrate that Cl-PFAESs might cause TH disruption effects through competitive binding to transport proteins and activation of TRs.

Chlorinated Polyfluorinated Ether Sulfonates Exhibit Higher Activity toward Peroxisome Proliferator-Activated Receptors Signaling Pathways than Perfluorooctanesulfonate.

Chlorinated polyfluorinated ether sulfonates (Cl-PFAESs) are the alternative products of perfluorooctanesulfonate (PFOS) in the metal plating industry in China. The similarity in chemical structures between Cl-PFAESs and PFOS makes it reasonable to assume they possess similar biological activities. In the present study, we investigated whether Cl-PFAESs could induce cellular effects through peroxisome proliferator-activated receptors (PPARs) signaling pathways like PFOS. By using fluorescence competitive binding assay, we found two dominant Cl-PFAESs (6:2 Cl-PFAES and 8:2 Cl-PFAES) bound to PPARs with affinity higher than PFOS. Based on the luciferase reporter gene transcription assay, the two Cl-PFAESs also showed agonistic activity toward PPARs signaling pathways with potency similar to (6:2 Cl-PFAES) or higher than (8:2 Cl-PFAES) PFOS. Molecular docking simulation showed the two Cl-PFAESs fitted into the ligand binding pockets of PPARs with very similar binding mode as PFOS. The cell function results showed Cl-PFAESs promoted the process of adipogenesis in 3T3-L1 cells with potency higher than PFOS. Taken together, we found for the first time that Cl-PFAESs have the ability to interfere with PPARs signaling pathways, and current exposure level of 6:2 Cl-PFAES in occupational workers has exceeded the margin of safety. Our study highlights the potential health risks of Cl-PFAESs as PFOS alternatives.

Bisphenol AF and Bisphenol B Exert Higher Estrogenic Effects than Bisphenol A via G Protein-Coupled Estrogen Receptor Pathway.

Numerous studies have indicated estrogenic disruption effects of bisphenol A (BPA) analogues. Previous mechanistic studies were mainly focused on their genomic activities on nuclear estrogen receptor pathway. However, their nongenomic effects through G protein-coupled estrogen receptor (GPER) pathway remain poorly understood. Here, using a SKBR3 cell-based fluorescence competitive binding assay, we found six BPA analogues bound to GPER directly, with bisphenol AF (BPAF) and bisphenol B (BPB) displaying much higher (∼9-fold) binding affinity than BPA. Molecular docking also demonstrated the binding of these BPA analogues to GPER. By measuring calcium mobilization and cAMP production in SKBR3 cells, we found the binding of these BPA analogues to GPER lead to the activation of subsequent signaling pathways. Consistent with the binding results, BPAF and BPB presented higher agonistic activity than BPA with the lowest effective concentration (LOEC) of 10 nM. Moreover, based on the results of Boyden chamber and wound-healing assays, BPAF and BPB displayed higher activity in promoting GPER mediated SKBR3 cell migration than BPA with the LOEC of 100 nM. Overall, we found two BPA analogues BPAF and BPB could exert higher estrogenic effects than BPA via GPER pathway at nanomolar concentrations.

A High-Throughput Screening Approach for Evaluating the Binding Affinity of Environmental Pollutants to Nuclear Receptors.

Increasing levels of compounds have been detected in the environment, causing widespread pollution and posing risks to human health. However, despite their high environmental occurrence, there is very limited information regarding their toxicological effects. It is urgent to develop high-throughput screening (HTS) methods to guide toxicological studies. In this study, a receptor-ligand binding assay using an HTS system was developed to determine the binding potency of environmental pollutants on nuclear receptors. The test is conducted using a microplate reader (i.e., a 96-well plate containing various chemicals) by measuring the fluorescence polarization (FP) of a specific fluorescent probe. This assay consists of four parts: the construction and transformation of recombinant vectors, the expression and purification of the receptor protein (ligand-binding domain), receptor-probe binding, and competitive binding of chemicals with the receptor. The binding potency of two environmental pollutants, perfluorooctanesulfonic acid (PFOS) and triphenyl phosphate (TPHP), with peroxisome proliferator-activated receptor gamma (PPARγ) was determined to illustrate the assay procedure. Finally, the advantages and disadvantages of this method and its potential applications were also discussed.

Competitive relationships due to similar nutrient preferences reshape soil bacterial metacommunities.

Paddy soil, as an ecosystem with alternating drained and flooded conditions, microorganisms in it can maintain the stability of the ecosystem by regulating the composition and diversity of its species when disturbed by external biotic or abiotic factors, and the regulatory mechanism in this process is a controversial topic in ecological research. In this study, we investigate the effects of pigeon feces addition on bacterial communities in three textured soils, two conditions (drained and flooded) based on microcosm experiment using high-throughput sequencing techniques. Our results show that pigeon feces addition reduced environmental heterogeneity and community diversity, both under flooded and drained conditions and in all textured soils, thereby decreasing the effectiveness of environmental selection and increasing diffusion limitations among bacterial communities. Bacterial communities are altered by environmental factors including total organic carbon, available nitrogen, total phosphorus, available phosphorus and available potassium, resulting in the formation of new community structures and dominant genera. Bacteria from pigeon feces did not colonize the original soil in large numbers, and the soil bacterial community structure changed, with some species replaced the indigenous ones as new dominant genera. As nutrient diffusion increases the nutrient content of the soil, this does not lead to species extinction; however, nutrient diffusion creates new nutrient preferences of the bacterial community, which causes direct competition between species, and contributes to the extinction and immigration species. Our results suggest that species replacement is an adaptive strategy of soil bacterial community in response to dispersal of pigeon feces, and that bacterial community regulate diversity and abundance of the community by enhancing species extinction and immigration, thereby preventing bacteria in pigeon feces from colonizing paddy soils and maintaining ecosystem stability.

Fine particulate matter disrupts bile acid homeostasis in hepatocytes via binding to and activating farnesoid X receptor.

Fine particulate matter (PM2.5)-induced metabolic disorders have attracted increasing attention, however, the underlying molecular mechanism of PM2.5-induced hepatic bile acid disorder remains unclear. In this study, we investigated the effects of PM2.5 components on the disruption of bile acid in hepatocytes through farnesoid X receptor (FXR) pathway. The receptor binding assays showed that PM2.5 extracts bound to FXR directly, with half inhibitory concentration (IC50) value of 21.7 µg/mL. PM2.5 extracts significantly promoted FXR-mediated transcriptional activity at 12.5 µg/mL. In mouse primary hepatocytes, we found PM2.5 extracts (100 µg/mL) significantly decreased the total bile acid levels, inhibited the expression of bile acid synthesis gene (Cholesterol 7 alpha-hydroxylase, Cyp7a1), and increased the expression of bile acid transport genes (Multidrug resistance associated protein 2, Abcc2; and Bile salt export pump, Abcb11). Moreover, these alterations were significantly attenuated by knocking down FXR in hepatocytes. We further divided the organic components and water-soluble components from PM2.5, and found that two components bound to and activated FXR, and decreased the bile acid levels in hepatocytes. In addition, benzo[a]pyrene (B[a]P) and cadmium (Cd) were identified as two bioactive components in PM2.5-induced bile acid disorders through FXR signaling pathway. Overall, we found PM2.5 components could bind to and activate FXR, thereby disrupting bile acid synthesis and transport in hepatocytes. These new findings also provide new insights into PM2.5-induced toxicity through nuclear receptor pathways.

Triclocarban exhibits higher adipogenic activity than triclosan through peroxisome proliferator-activated receptors pathways.

Previous epidemiological and animal studies have showed the lipid metabolic disruption of antimicrobial triclocarban (TCC) and triclosan (TCS). However, the present in vivo researches were mainly devoted to the hepatic lipid metabolism, while the evidence about the impacts of TCC/TCS on the adipose tissue is very limited and the potential mechanism is unclear, especially the molecular initiation events. Moreover, little is known about the toxic difference between TCC and TCS. This study aimed to demonstrate the differential adipogenic activity of TCC/TCS as well as the potential molecular mechanism via peroxisome proliferator-activated receptors (PPARα/ß/γ). The in vitro experiment based on 3T3-L1 cells showed that TCC/TCS promoted the differentiation of preadipocytes into mature adipocytes at nanomolar to micromolar concentrations, which was approach to their human exposure levels. We revealed for the first time by reporter gene assay that TCC could activate three PPARs signaling pathways in a concentration-dependent manner, while TCS only activate PPARß. The molecular docking strategy was applied to simulate the interactions of TCC/TCS with PPARs, which explained well the different PPARs activities between TCC and TCS. TCC up-regulated the mRNA expression of three PPARs, but TCS only up-regulated PPARß and PPARγ significantly. Meanwhile, TCC/TCS also promoted the expression of adipogenic genes targeted by PPARs to different extent. The cellular and simulating studies demonstrated that TCC exerted higher adipogenic effects and PPARs activities than TCS. Our mice in vivo experiment showed that TCC could lead to adipocyte size increase, adipocyte lipid accumulation growing, fat weight and body weight gain at human-related exposure levels, and high fat diet exacerbated these effects. Moreover, male mice tended to be more susceptible to TCC induced obesogenic effect than female mice. This work highlights the potential obesogenic risks of TCC/TCS via PPARs signaling pathways, and TCC deserves more concerns for its higher activity.

piR-27222 mediates PM2.5-induced lung cancer by resisting cell PANoptosis through the WTAP/m6A axis.

PM2.5 pollution has been associated with the incidence of lung cancer, but the underlying mechanism is still unclear. PIWI-interacting RNAs (piRNAs), initially identified in germline cells, have emerged as a novel class of small non-coding RNAs (26 - 32 nucleotides) with diverse functions in various diseases, including cancer. However, the role and mechanism of piRNAs in the development of PM2.5-induced lung cancer remain to be clarified. In the presented study, we used a PM2.5-induced malignant transformation cell model to analyze the change of piRNA profiles. Among the disturbed piRNAs, piR-27222 was identified as an oncogene that inhibited cell death in a m6A-dependent manner. Mechanistically, we found that piR-27222 could deubiquitinate and stabilize eIF4B by directly binding to eIF4B and reducing its interaction with PARK2. The enhanced expression of eIF4B, in turn, promoted the expression of WTAP, leading to increased m6A modification in the Casp8 transcript. Consequently, the stability of Casp8 transcripts was reduced, rendering lung cancer cells resistant to PANoptosis. Collectively, our findings reveal that PM2.5 exposure up-regulated piR-27222 expression, which could affect EIF4B/WTAP/m6A axis, thereby inhibiting PANoptosis of cells and promoting lung cancer. Our study provides new insights into understanding the epigenetic mechanisms underlining PM2.5-induced lung cancer.

Lysine ß-hydroxybutyrylation promotes lipid accumulation in alcoholic liver disease.

Continuous (chronic or sub-chronic) alcohol consumption induces a metabolic byproduct known as ketone bodies, and the accumulation of ketones leads to a life-threatening syndrome called alcoholic ketoacidosis. However, the mechanism underlining the physiological effects of ketone accumulation in alcoholic liver disease (ALD) is still in its infancy. Here, we discovered that mitochondrial acetyl-CoA accumulation was diverted into the ketogenesis pathway in ethanol-fed mice and ethanol-exposed hepatocytes. Unexpectedly, global protein lysine ß-hydroxybutyrylation (Kbhb) was induced in response to increased ketogenesis-derived ß-hydroxybutyrate (BHB) levels both in hepatocytes and in livers of mice. Focusing on the solute carrier family (SLCs), we found that SLC25A5 presented obvious Kbhb at lysine residues 147 and 166. Kbhb modifications at these two lysine residues stabilized SLC25A5 expression by blocking ubiquitin-proteasome pathway. Subsequent mutation analysis revealed that Kbhb of SLC25A5 at K147 and K166 had site-specific regulatory roles by increasing peroxisome proliferator activated receptor gamma (PPARγ) expression, which further promoting lipogenesis. Additionally, 3-hydroxy-3-methylglutaryl-coenzyme A synthase 2 (HMGCS2), a rate-limiting enzyme for BHB production, was profoundly induced by ethanol exposure, and knockout of Hmgcs2 with CRISPR/Cas9 attenuated SLC25A5 Kbhb. Together, our study demonstrated a widespread Kbhb landscape under ethanol exposure and clarified a physiological effect of Kbhb modification on liver lipid accumulation.