Fatty Hepatocytes Research Articles

TEC-mediated tRF-31R9J regulates histone lactylation and acetylation by HDAC1 to suppress hepatocyte ferroptosis and improve non-alcoholic steatohepatitis

BackgroundTectorigenin (TEC) is a monomer of anthocyanin, which we found exhibits hepatoprotective effects. tRNA-derived fragments (tRFs) and ferroptosis play important roles in the pathogenesis of non-alcoholic steatohepatitis (NASH). Recent discoveries have revealed that histone lactylation and acetylation play a crucial role in connecting cellular metabolism and epigenetic regulation through post-translational modification of histones. However, it is unclear whether TEC improves NASH by regulating histone lactylation, acetylation and hepatocyte ferroptosis through tRFs.ResultsIn this study, we demonstrated that TEC significantly inhibits free fatty acids-induced hepatocyte ferroptosis both in vitro and in vivo. We identified tRF-31R9J (tRF-31-R9JP9P9NH5HYD) involved in TEC regulation of ferroptosis in steatosis hepatocytes. Overexpression of tRF-31R9J suppressed hepatocyte ferroptosis and enhanced cell viability in steatosis HepG2 cells. Knockdown of tRF-31R9J partially counteracted the inhibitory effect of TEC on ferroptosis in hepatocytes. Mechanistically, tRF-31R9J recruited HDAC1 to reduce the levels of histone lactylation and acetylation modifications of the pro-ferroptosis genes ATF3, ATF4, and CHAC1, thereby inhibiting their gene expression.ConclusionsThis study demonstrates that TEC-mediated tRF-31R9J inhibits hepatocyte ferroptosis through HDAC1-regulated histone delactylation and deacetylation, thereby improving NASH. These discoveries offer a theoretical foundation and new strategies for the medical management of NASH.

Novel Therapies for Nonalcoholic Steatohepatitis (NASH) and Cardiovascular Risk Reduction.

Nonalcoholic steatohepatitis (NASH) is a type of nonalcoholic fatty liver disease (NAFLD) characterized by hepatocyte injury and inflammation, in addition to only the presence of steatosis NAFLD. We review the existing data on available novel therapies for NASH and NAFLD and also discuss several therapies in development. We assessed therapies for NASH by searching the databases of PubMed, EMBASE, and Web of Science (SCI) from their inception dates until September 15, 2024. Search terms used were: nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, liver inflammation and hepatocyte injury.Until very recently, therapeutic lifestyle change was the primary modality of treatment for NASH, including modification of diet and physical activity. The FDA recently approved resmetirom using its expedited approval mechanism for NASH. There are also several pharmacotherapies in development for NASH which aim at weight loss, insulin sensitization and improvement in lipid levels, although some drugs may have multiple effects which are discussed. The availability of resmetirom offers patients with NASH an effective adjunctive therapy in addition to lifestyle changes. Several other novel therapies are also currently being tested and will add to our therapeutic armamentarium.

Structural elucidation of an active arabinoglucan from Gomphrena globosa and its protection effect and mechanism against metabolic dysfunction-associated steatohepatitis

The flower of Gomphrena globosa (G. globosa.) is used as Chinese traditional medicine and functional food. Extractions from G. globosa. have been reported to exert hepatoprotective effects. We further hypothesized that the polysaccharide components, as a bioactive ingredient, might have anti-fatty and hepatitis function. Here, a novel homogeneous arabinoglucan GGL0.05S1 (Mw = 83.9 kDa) from this flower, was characterized by monosaccharide composition analysis, methylation analysis, and NMR. Structural analysis showed that the backbone of GGL0.05S1 consists of →4)-α-Glcp-(1→ and →4,6)-α-Glcp-(1→ residues, and the branched chain linked to the main chain via C-6 of →4,6)-α-Glcp-(1→ in the form α-Araf-(1→[4)-α-Glcp-(1]b→ (b > 2). In vitro experiments demonstrated that GGL0.05S1 could inhibit lipid deposition and ROS overload in free fatty acid-induced hepatocytes, meanwhile in vivo tests showed that GGL0.05S1 effectively protected against liver injury, steatohepatitis, and fibrosis in a CDA-HFD-fed MASH model. Mechanism study further uncovered that GGL0.05S1 augmented the expression and antioxidant ability of thioredoxin protein that ameliorated oxidative stress, promoted fatty acid β-oxidation and mitophagy, up to reducing lipotoxicity and alleviating inflammation via inhibiting NLRP3 signaling pathway. Overall, GGL0.05S1 might be a potential novel active compound with liver-protective effect from G. globosa., and which is informative for anti-MASH new drug development.

Evaluating the therapeutic effect of different forms of silymarin on liver status and expression of some genes involved in fat metabolism, antioxidants and anti-inflammatory in older laying hens.

Silymarin, the predominant compound of milk thistle, is an extract took out from milk thistle (Silybum marianum) seeds, containing a mixture of flavonolignans with strong antioxidant capability. The experiment was conducted using 70 Lohmann LSL-Lite hens at 80 weeks of age with 7 treatments each with 10 replicates. Treatments included: (1) control diet without silymarin, (2) daily intake of 100mg silymarin powder/kg body weight (BW) (PSM100), (3) daily intake of 200mg silymarin powder/kg BW (PSM200), (4) daily intake of 100mg nano-silymarin/kg BW (NSM100), (5) daily intake of 200mg nano-silymarin/kg BW (NSM200), (6) daily intake of 100mg lecithinized silymarin/kg BW (LSM100) and (7) daily intake of 200mg lecithinized silymarin/kg BW (LSM200). The birds were housed individually, and diets were fed for 12 weeks. Scanning electron microscopy showed that NSM was produced with the average particle size of 20.30nm. Silymarin treatment improved serum antioxidant enzyme activity. All groups receiving silymarin showed a decrease in liver malondialdehyde content, expression of fatty acid synthase, tumour necrosis factor alpha, interleukin 6 (IL-6) genes in the liver, and hepatic steatosis than the control, except those fed the PSM100 diet. There were decreases in liver dry matter and fat contents, non-alcoholic fatty liver disease and hepatocyte ballooning, and an increase in glutathione peroxidase gene expression and a decrease in iNOS gene expression in birds fed the NSM100, NSM200, LSM100 and LSM200 diets compared to the control group. Moreover, all groups receiving silymarin showed a significant decrease in liver weight compare to the control group. Overall, the effects of silymarin when converted to NSM or LSM and offered at the level of 200mg/kg BW were more pronounced on the hepatic variables and may be useful in the prevention of the liver disease in older laying hens.

Plant miR6262 Modulates the Expression of Metabolic and Thermogenic Genes in Human Hepatocytes and Adipocytes.

Edible plants have been linked to the mitigation of metabolic disturbances in liver and adipose tissue, including the decrease of lipogenesis and the enhancement of lipolysis and adipocyte browning. In this context, plant microRNAs could be key bioactive molecules underlying the cross-kingdom beneficial effects of plants. This study sought to explore the impact of plant-derived microRNAs on the modulation of adipocyte and hepatocyte genes involved in metabolism and thermogenesis. Plant miR6262 was selected as a candidate from miRBase for the predicted effect on the regulation of human metabolic genes. Functional validation was conducted after transfection with plant miRNA mimics in HepG2 hepatocytes exposed to free fatty acids to mimic liver steatosis and hMADs cells differentiated into brown-like adipocytes. miR6262 decreases the expression of the predicted target RXRA in the fatty acids-treated hepatocytes and in brown-like adipocytes and affects the expression profile of critical genes involved in metabolism and thermogenesis, including PPARA, G6PC, SREBF1 (hepatocytes) and CIDEA, CPT1M and PLIN1 (adipocytes). Nevertheless, plant miR6262 mimic transfections did not decrease hepatocyte lipid accumulation or stimulate adipocyte browning. these findings suggest that plant miR6262 could have a cross-kingdom regulation relevance through the modulation of human genes involved in lipid and glucose metabolism and thermogenesis in adipocytes and hepatocytes.

Euphorbia milii and propolis combination tea reduced hepatic steatosis and hepatocyte apoptosis in high-fat diet rat model

Background: Dyslipidemia can cause various organ disorders, such as fatty liver disease. Over time, fatty liver disease has become more commonplace worldwide and may cause mortality if the progression worsens. Natural components from Euphorbia milii (E. milii) and propolis (EMP) have been demonstrated as immunomodulators that reduce total cholesterol levels.Objective: To prove the effect of EMP tea on inhibiting fatty liver and hepatocyte apoptosis in high-fat diet (HFD)-induced rats.Methods: This study applied a post-test-only control group design using 18 Wistar rats, which were divided into three groups: K0 (received standard feed), KN (received HFD of 2 g/200 g Body weight (BW) in a day), and P (received HFD of 2 g/200 g BW in a day and EMP of tea 40 mg/100 g BW in a day). The interventions were conducted for 30 days, followed by termination on day 31 for liver tissue collection and analysis. We calculated the hepatic steatosis with the help of hematoxylin-eosin (HE) staining. Hepatocyte apoptosis was also determined with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining.Results: The K0 group had a lower hepatic steatosis percentage (17.87 ± 1.81) than KN (63.75 ± 15.88). We also found no hepatocyte apoptosis in the K0 but a high hepatocyte apoptosis index in the KN (3.98 ± 0.29). The combination of EMP tea in HFD-induced rats significantly reduced hepatic steatosis and apoptosis percentage (25.33 ± 1.17 and 0.91 ± 0.61, respectively). Conclusion: We demonstrated that combining EMP tea reduced hepatic steatosis and hepatocyte apoptotic index in HFD-induced rats, suggesting its potential as a treatment for these conditions.

Regulation of lipid metabolism in grass carpprimaryhepatocytes by exosomes derived from fatty hepatocytes though GRP78.

Exosomes regulate lipid metabolism by carrying miRNAs, nucleic acids, and proteins, thereby influencing the function of receptor cells. Glucose-regulated protein 78 (GRP78) is also involved in the regulation of lipid metabolism. However, it remains unclear whether exosomes derived from fatty hepatocytes (OA-Exo) regulate lipid metabolism through the enrichment of GRP78. In this study, we observed the expression of GRP78 was significantly increased in fatty hepatocytes (incubating hepatocytes with oleic acid (OA) for 24h) and OA-Exo (P < 0.05). In addition, OA-Exo (50μg/mL) and GRP78 protein (1μg/mL) significant increasedthe content of triacylglycerol (TG) and total cholesterol (TC), as well as up-regulatedthe expression of GRP78 and inositol-requiring enzyme-1alpha (IRE1α) protein (P < 0.05). We further used YUM70 (an inhibitor of GRP78) to inhibit endogenous GRP78, and compared with the YUM70 group, OA-Exo reversed the effect of YUM70 and increased the content of TG, TC, and the expression of GRP78 protein in hepatocytes (P < 0.05). Furthermore, the inhibition of the IRE1α pathway with 4μ8C resulted in a significant decrease in TG content compared to the control group (P < 0.05). However, when compared with the 4μ8C group, OA-Exo and GRP78 reversed the effect of 4μ8C and significantly increased TG content (P < 0.05). Taken together, these results indicated that OA-Exo activated IRE1α to promote lipid accumulation in hepatocytes through the enrichment of GRP78. This study provided a new perspective for further exploration of exosomal lipid metabolism in fish.

All-trans retinoic acid induces lipophagy by reducing Rubicon in Hepa1c1c7 cells

All-trans retinoic acid (atRA), a metabolite of vitamin A, reduces hepatic lipid accumulation in liver steatosis model animals. Lipophagy, a new lipolysis pathway, degrades a lipid droplet (LD) via autophagy in adipose tissue and the liver. We recently found that atRA induces lipophagy in adipocytes. However, it remains unclear whether atRA induces lipophagy in hepatocytes. In this study, we investigated the effects of atRA on lipophagy in Hepa1c1c7 cells and the liver of mice fed a high-fat diet (HFD). First, we confirmed that atRA induced autophagy in Hepa1c1c7 cells by Western blotting and the GFP-LC3-mCherry probe. Next, we evaluated the lipolysis in fatty Hepa1c1c7 cells treated with the knockdown of Atg5, an essential gene in autophagy induction. Atg5-knockdown partly suppressed the atRA-induced lipolysis in fatty Hepa1c1c7 cells. We also found that atRA reduced the protein, but not mRNA, expression of Rubicon, a negative regulator of autophagy, in Hepa1c1c7 cells and the liver of HFD-fed mice. Rubicon-knockdown partly inhibited the atRA-induced lipolysis in fatty Hepa1c1c7 cells. In addition, atRA reduced hepatic Rubicon expression in young mice, but the effect of atRA on it diminished in aged mice. Finally, we investigated the mechanism underlying reduced Rubicon protein expression by atRA in hepatocytes. A protein synthesis inhibitor, but not proteasome or lysosomal inhibitors, significantly blocked the reduction of Rubicon protein expression by atRA in Hepa1c1c7 cells. These results suggest that atRA may promote lipophagy in fatty hepatocytes by reducing hepatic Rubicon expression via inhibiting protein synthesis.

Proteomic analysis of exosomes derived from fatty hepatocytes of grass carp.

Exosomes participate in intercellular communication by carrying proteins, messenger RNA, microRNAs, and non-coding RNA. Fatty liver is a common phenomenon in farmed fish, but there has been little study of fatty hepatocytes-derived exosomes. Here, we successfully isolated exosomes from hepatocytes of grass carp, named Exos (hepatocytes-derived exosomes) and OA-Exos (fatty hepatocytes-derived exosomes), from which 617 differentially expressed proteins were identified using liquid chromatography tandem mass spectrometry. Of these, 320 proteins were promoted and 297 proteins were restrained, which were gathered in biological processes and cellular components (cellular processes, cells, and intracellular structures). The results of kyoto encyclopedia of genes and genomes (KEGG) analysis revealed that the differential expression proteins were gathered in "carbohydrate transport and metabolism", "translation, ribosomal structure and biogenesis", "posttranslational modification, protein turnover, chaperones", and "intracellular trafficking, secretion, and vesicular transport". In addition, five differentially expressed exosomal proteins were further confirmed by parallel reaction monitoring, including 2-phospho-D-glycerate hydrolyase, cytochrome b5, fatty acid-binding protein domain-containing protein, metallothionein, and malate dehydrogenas, which were downregulated. These findings provided evidence that exosomes derived from fatty hepatocytes of grass carp may be biomarkers for the early diagnosis, treatment, and prevention of fatty liver in fishery development.

Diosgenin attenuates nonalcoholic hepatic steatosis through the hepatic SIRT1/PGC-1α pathway

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing worldwide in recent years, causing severe economic and social burdens. Therefore, the lack of currently approved drugs for anti-NAFLD has gradually gained attention. SIRT1, as a member of the sirtuins family, is now the most widely studied in the pathophysiology of many metabolic diseases, and has great potential for preventing and treating NAFLD. Natural products such as Diosgenin (DG) have the potential to be developed as clinical drugs for the treatment of NAFLD due to their excellent multi-target therapeutic effects. In this study, we found that DG can activate the SIRT1/PGC-1α pathway and upregulate the expression of its downstream targets nuclear respiratory factor 1 (NRF1), complex IV (COX IV), mitofusin-2 (MFN2), and PPARα (perox-isome proliferator-activated receptor α) in SD rats induced by high-fat diet (HFD) and HepG2 cells caused by free fatty acids (FFAs, sodium oleate: sodium palmitate = 2:1). Conversely, the levels of dynamin-related protein 1 (DRP1) and inflammatory factors, including NF-κB p65, IL6, and TNFα, were downregulated both in vitro and in vivo. This improved mitochondrial dysfunction, fatty acid oxidation (FAO), lipid accumulation, steatosis, oxidative stress, and hepatocyte inflammation. Subsequently, we applied SIRT1 inhibitor EX527 and SIRT1 agonist SRT1720 to confirm further the necessity of activating SIRT1 for DG to exert therapeutic effects on NAFLD. In summary, these results further demonstrate the potential therapeutic role of DG as a SIRT1 natural agonist for NAFLD. (Graphical Abstracts)

Competitive adsorption of microRNA-532-3p by circular RNA SOD2 activates Thioredoxin Interacting Protein/NLR family pyrin domain containing 3 pathway and promotes pyroptosis of non-alcoholic fatty hepatocytes

ObjectiveThere is a growing body of evidence indicating that pyroptosis, a programmed cell death mechanism, plays a crucial role in the exacerbation of inflammation and fibrosis in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Circular RNAs (circRNAs), functioning as vital regulators within NAFLD, have been shown to mediate the process of cell pyroptosis. This study aims to elucidate the roles and mechanisms of circRNAs in NAFLD.MethodsUtilizing a high-fat diet (HFD)-induced rat model for in vivo experimentation and hepatocytes treated with palmitic acid (PA) for in vitro models, we identified circular RNA SOD2 (circSOD2) as our circRNA of interest through analysis with the circMine database. The expression levels of associated genes and pyroptosis-related proteins were determined using quantitative real-time polymerase chain reaction and Western blotting, alongside immunohistochemistry. Serum liver function markers, cellular inflammatory cytokines, malondialdehyde, lactate dehydrogenase levels, and mitochondrial membrane potential, were assessed using enzyme-linked immunosorbent assay, standard assay kits, or JC-1 staining. Flow cytometry was employed to detect pyroptotic cells, and lipid deposition in liver tissues was observed via Oil Red O staining. The interactions between miR-532-3p/circSOD2 and miR-532-3p/Thioredoxin Interacting Protein (TXNIP) were validated through dual-luciferase reporter assays and RNA immunoprecipitation experiments.ResultsOur findings demonstrate that, in both in vivo and in vitro NAFLD models, there was an upregulation of circSOD2 and TXNIP, alongside a downregulation of miR-532-3p. Mechanistically, miR-532-3p directly bound to the 3'-UTR of TXNIP, thereby mediating inflammation and cell pyroptosis through targeting the TXNIP/NLR family pyrin domain containing 3 (NLRP3) inflammasome signaling pathway. circSOD2 directly interacted with miR-532-3p, relieving the suppression on the TXNIP/NLRP3 signaling pathway. Functionally, the knockdown of circSOD2 or TXNIP improved hepatocyte pyroptosis; the deletion of miR-532-3p reversed the effects of circSOD2 knockdown, and the deletion of TXNIP reversed the effects of circSOD2 overexpression. Furthermore, the knockdown of circSOD2 significantly mitigated the progression of NAFLD in vivo.ConclusioncircSOD2 competitively sponges miR-532-3p to activate the TXNIP/NLRP3 inflammasome signaling pathway, promoting pyroptosis in NAFLD.

Lipidomics and biodistribution of extracellular vesicles‐secreted by hepatocytes from Zucker lean and fatty rats

AbstractExtracellular vesicles (EVs) have been involved in metabolic syndrome, although their specific role in the development of the pathology is still unknown. To further study the role of EVs, we have analysed by Raman tweezers microspectroscopy and mass spectrometry‐based lipidomics the small EVs population secreted by fatty (ZF) and lean (ZL) hepatocytes obtained from Zucker rats. We have also explored in vivo and ex vivo biodistribution of these EVs through fluorine‐18‐radiolabelling using a positron emission tomography imaging. Based on the proportion of proteins to lipids and the types of lipids, our results indicate that within the range of small EVs, primary hepatocytes secrete different subpopulations of particles. These differences were observed in the enrichment of triglyceride species in EVs secreted by ZF hepatocytes. Biodistribution experiments showed accumulation in the brain, heart, lungs, kidney and specially in bladder after intravenous administration. In summary, we show that EVs released by a fatty hepatocytes carry a different lipid signature compared to their lean counterpart. Biodistribution experiment has shown no difference in the distribution of EVs secreted by ZF and ZL hepatocytes but has given us a first view of possible target organs for these particles. Our results might open a door to both pathology studies and therapeutic interventions.

Osteocalcin activates lipophagy via the ADPN-AMPK/PPARα-mTOR signaling pathway in chicken embryonic hepatocyte

Fatty liver hemorrhage syndrome (FLHS) is the leading cause of noninfectious mortality in caged layers worldwide. Osteocalcin (OCN) is a protein secreted by osteoblasts, and its undercarboxylated form (ucOCN) acts as a multifunctional hormone that protects laying hens from FLHS. Lipophagy is a form of selective autophagy that breaks down lipid droplets (LDs) through lysosomes, and defective lipophagy is associated with FLHS. The aim of this study was to investigate the effects of ucOCN on the lipophagy of chicken embryonic hepatocytes and associated the function of the adiponectin (ADPN) signaling pathway. In this study, chicken embryonic hepatocytes were divided into 5 groups: control (CONT), fat emulsion (FE, 10% FE, v/v), FE with ucOCN at 1 ng/mL (FE-LOCN), 3 ng/mL (FE-MOCN), and 9 ng/mL (FE-HOCN). In addition, 4 μM AdipoRon, an adiponectin receptor agonist, was used to investigate the function of ADPN. The results showed that compared with CONT group, FE promoted the levels of phosphorylation of mammalian target of rapamycin (p-mTOR) (P < 0.05) and decreased the mRNA expression of ADNP receptors (AdipoR1 and AdipoR2). Compared with FE group, 3 and 9 ng/mL ucOCN inhibited the levels of autophagy adaptor p62 and p-mTOR (P < 0.05), increased the ratios of LC3-II/LC3-I (P < 0.05) and phosphorylated adenosine 5'-monophosphate-activated protein kinase (p-AMPK)/AMPK (P < 0.05), as well as the levels of peroxisome proliferator-activated receptor α (PPAR-α) and ADPN (P < 0.05). In addition, ucOCN at the tested concentrations increased the colocalization of LC3 and LDs in fatty hepatocytes. Administrated 4 μM AdipoRon activated AdipoR1 and AidpoR2 mRNA expression (P < 0.05), decreased the concentrations of triglyceride (P < 0.05), without effects on cell viability (P > 0.05). AdipoRon also increased the LC3-II/LC3-I ratio (P < 0.05) and the levels of p-AMPK/AMPK and PPAR-α (P < 0.05). In conclusion, the results reveal that ucOCN regulates lipid metabolism by activating lipophagy via the ADPN-AMPK/PPARα-mTOR signaling pathway in chicken embryonic hepatocytes. The results may provide new insights for controlling FLHS in laying hens.

MiR-484 promotes nonalcoholic fatty liver disease progression in mice via downregulation of Sorbs2.

MicroRNA 484 (miR-484) plays a pivotal role in the development and progression of different diseases and is typically described as a mitochondrial regulator. Whether miR-484 is involved in lipid metabolism or exerts a role in nonalcoholic fatty liver disease remains unclear. miR-484 levels were examined in the livers of male mice fed a high-fat diet and in hepatocytes treated with free fatty acids. Sorbin and SH3 structural domain-containing protein 2 (Sorbs2) were identified as a novel target of miR-484 by sequencing mRNA in the livers of miR-484 knockout mice. Sorbs2 liver-specific knockdown mice were constructed by tail vein injection of adeno-associated virus vector to miR-484 knockout mice. In addition, genetic manipulation of SORBS2 was performed in human hepatocyte lines, mouse primary hepatocytes, and the liver. Serum and hepatic miR-484 levels are upregulated in nonalcoholic fatty liver disease mice. miR-484 knockdown ameliorated hepatocyte steatosis, whereas miR-484 overexpression increased hepatocyte lipid load. miR-484 knockdown-mediated alleviation of hepatic steatosis, liver injury, inflammation, and apoptosis was compromised after high-fat diet-induced knockdown of Sorbs2 in mouse liver and free fatty acid-induced primary mouse hepatocytes. These results identify Sorbs2-mediated mitochondrial β-oxidation and apoptosis that promote miR-484 knockdown-mediated remission of hepatic steatosis.

Menin orchestrates hepatic glucose and fatty acid uptake via deploying the cellular translocation of SIRT1 and PPARγ

BackgroundMenin is a scaffold protein encoded by the Men1 gene, which interacts with various transcriptional proteins to activate or repress cellular processes and is a key mediator in multiple organs. Both liver-specific and hepatocyte-specific Menin deficiency promotes high-fat diet-induced liver steatosis in mice, as well as insulin resistance and type 2 diabetic phenotype. The potential link between Menin and hepatic metabolism homeostasis may provide new insights into the mechanism of fatty liver disease.ResultsDisturbance of hepatic Menin expression impacts metabolic pathways associated with non-alcoholic fatty liver disease (NAFLD), including the FoxO signaling pathway, which is similar to that observed in both oleic acid-induced fatty hepatocytes model and biopsied fatty liver tissues, but with elevated hepatic Menin expression and inhibited FABP1. Higher levels of Menin facilitate glucose uptake while restraining fatty acid uptake. Menin targets the expression of FABP3/4/5 and also CD36 or GK, PCK by binding to their promoter regions, while recruiting and deploying the cellular localization of PPARγ and SIRT1 in the nucleus and cytoplasm. Accordingly, Menin binds to PPARγ and/or FoxO1 in hepatocytes, and orchestrates hepatic glucose and fatty acid uptake by recruiting SIRT1.ConclusionMenin plays an orchestration role as a transcriptional activator and/or repressor to target downstream gene expression levels involved in hepatic energy uptake by interacting with the cellular energy sensor SIRT1, PPARγ, and/or FoxO1 and deploying their translocations between the cytoplasm and nucleus, thereby maintaining metabolic homeostasis. These findings provide more evidence suggesting Menin could be targeted for the treatment of hepatic steatosis, NAFLD or metabolic dysfunction-associated fatty liver disease (MAFLD), and even other hepatic diseases.Graphical

METTL3 exacerbates insulin resistance in hepatocytes by regulating m6A modification of cytochrome P450 2B6

BackgroundInsulin resistance (IR) in hepatocytes endangers human health, and frequently results in the development of non-alcoholic fatty liver disease (NAFLD). Research on m6A methylation of RNA molecules has gained popularity in recent years; however, the molecular mechanisms regulating the processes of m6A modification and IR are not known. The cytochrome P450 (CYP450) enzyme system, which is mainly found in the liver, is associated with the pathogenesis of NAFLD. However, few studies have been conducted on CYP450 related m6A methylation. Here, we investigated the role of the methyltransferase METTL3 in exacerbating IR in hepatocytes, mainly focusing on the regulation of m6A modifications in CYP2B6.Methods and resultsAnalysis using dot blot and epitranscriptomic chips revealed that the m6A modification pattern of the transcriptome in high-fat diet (HFD)-induced fatty liver and free fatty acid (FFA)-induced fatty hepatocytes showed significant changes. CYP450 family members, especially Cyp2b10, whose homolog in humans is CYP2B6, led to a noticeable increase in m6A levels in HFD-induced mice livers. Application of the METTL3 methyltransferase inhibitor, STM2457, increased the level of insulin sensitivity in hepatocytes. We then analyzed the role of METTL3 in regulating m6A modification of CYP2B6 in hepatocytes. METTL3 regulated the m6A modification of CYP2B6, and a positive correlation was found between the levels of CYP2B6 translation and m6A modifications. Furthermore, interference with METTL3 expression and exposure to STM2457 inhibited METTL3 activity, which in turn interfered with the phosphorylated insulin receptor substrate (pIRS)-glucose transporter 2 (GLUT2) insulin signaling pathway; overexpression of CYP2B6 hindered IRS phosphorylation and translocation of GLUT2 to membranes, which ultimately exacerbated IR.ConclusionThese findings offer unique insights into the role that METTL3-mediated m6A modifications of CYP2B6 play in regulating insulin sensitivity in hepatocytes and provide key information for the development of strategies to induce m6A modifications for the clinical treatment of NAFLD.

Bifidobacterium animalis subspecies lactis HN019 can reduce the sequelae of experimental periodontitis in rats modulating intestinal parameters, expression of lipogenic genes, and levels of hepatic steatosis.

To determine whether Bifidobacterium animalis subspecies lactis HN019 (B. lactis HN019) can reduce the sequelae of experimental periodontitis (EP) in rats modulating systemic parameters. This study evaluated the effects of probiotic therapy (PROB) in the prevention of local and systemic damage resulting from EP. Forty-eight rats were allocated into four groups: C (control), PROB, EP, and EP-PROB. PROB (1 × 1010 CFU/mL) administration lasted 8 weeks and PE was induced on the 7th week by placing ligature on the animals' lower first molars. All animals were euthanized in the 9th week of the experiment. Biomolecular analyses, RT-PCR, and histomorphometric analyses were performed. The data obtained were analyzed statistically (ANOVA, Tukey, p < .05). The EP group had higher dyslipidemia when compared to the C group, as well as higher levels of insulin resistance, proteinuria levels, percentages of systolic blood pressure, percentage of fatty hepatocytes in the liver, and expression of adipokines was up-regulated (LEPR, NAMPT, and FABP4). All these parameters (except insulin resistance, systolic blood pressure, LEPR and FABP4 gene expression) were reduced in the EP-PROB group when compared to the EP group. The EP group had lower villus height and crypt depth, as well as a greater reduction in Bacteroidetes and a greater increase in Firmicutes when compared to the EP-PROB group. Greater alveolar bone loss was observed in the EP group when compared to the EP-PROB group. Bifidobacterium lactis HN019 can reduce the sequelae of EP in rats modulating intestinal parameters, attenuating expression of lipogenic genes and hepatic steatosis.

A near-infrared fluorescent probe for monitoring abnormal mitochondrial viscosity in cancer and fatty-liver mice model

Viscosity is an important component of cell microenvironment, and abnormal mitochondrial viscosity is associated with many diseases such as tumor and fatty liver. Herein, a near-infrared fluorescence probe (QX-V) based on quinoline-xanthene dye for detecting viscosity is constructed. In high viscosity medium, the free rotation of single bond is inhibited and the fluorescence is released. The probe shows high sensitivity together with good selectivity. Notably, QX-V has a long excitation wavelength (710 nm) and emission wavelength (786 nm). At the same time, the probe is a positively charged molecule that can target mitochondria. QX-V can not only distinguish cancer cells from normal cells, but also make a distinction between normal cells and fatty hepatocytes. In addition, QX-V is used to image viscosity abnormality in tumor-bearing mice. The probe also has a good ability to image viscosity abnormality caused by liver injury in fatty-liver mice.

Isolation of Regenerating Hepatocytes after Partial Hepatectomy in Mice.

Partial hepatectomy has been widely used to investigate liver regeneration in mice, but the isolation of high yields of viable hepatocytes for downstream single-cell applications is challenging. A marked accumulation of lipids within regenerating hepatocytes is observed during the first 2 days of normal liver regeneration in mice. This so-called transient regeneration-associated steatosis (TRAS) is temporary but partially overlaps the major proliferative phase. Density-gradient purification is the backbone of most existing protocols for the isolation of primary hepatocytes. As gradient purification relies on the density and size of cells, it separates non-steatotic from steatotic hepatocyte populations. Therefore, fatty hepatocytes often are lost, yielding non-representative hepatocyte fractions. The presented protocol describes an easy and reliable method for the in vivo isolation of regenerating hepatocytes regardless of their lipid content. Hepatocytes from male C57BL/6 mice are isolated 24-48 h after hepatectomy by a classic two-step collagenase perfusion approach. A standard peristaltic pump drives the warmed solutions via the catheterized inferior vena cava into the remnant, using a retrograde perfusion technique with outflow through the portal vein. Hepatocytes are dissociated by collagenase for their release from the Glisson's capsule. After washing and careful centrifugation, the hepatocytes can be used for any downstream analyses. In conclusion, this paper describes a straightforward and reproducible technique for the isolation of a representative population of regenerating hepatocytes after partial hepatectomy in mice. The method may also aid the study of fatty liver disease.

Fatty hepatocyte-derived exosomal miR-122 promotes lipid synthesis and reduces immunocompetence in grass carp (Ctenopharyngodon idella)

Exosomes are nano-sized extracellular vesicles (EVs) secreted by all cell types and are a large component of the broader class of EVs, which feature a bimolecular phospholipid membrane and are critical in inter-tissue communication. Cellular crosstalk between the liver and the immune system is known to be closely mediated by exosomes. Nevertheless, information is scarce regarding the exact interaction between the lipid metabolism and inflammatory functions of exosomal microRNAs (miRNAs) in aquatic animals. The current investigation first analyzes exosomes derived from fatty hepatocytes treated with oleic acid (OA). Fatty hepatocyte-derived exosomes (OA-Exosomes, OA-Exos) were sequenced by BGISEQ-500 sequencing technology and injected intraperitoneally into the grass carp. A total of 298 differentially expressed miRNAs were characterized in the grass carp fatty hepatocyte exosomes, of which 132 were upregulated miRNAs and 166 were downregulated miRNAs. Among the top 9 upregulated miRNAs with the highest differential expression, miR-18a-5p, miR-144, miR-122, and miR-143 were primarily involved in lipid metabolism. AST levels were remarkably elevated in the OA-Exos group (P < 0.05), while it demonstrated swollen hepatocytes, vacuolar degeneration, and increased hepatic lipid droplets in this group, indicating that exosomes promoted the formation of fatty liver and subsequent liver injury. In addition, the lipid synthesis genes ACC, FAS, PPARγ and SPEBP-1 were significantly upregulated (P < 0.05), while PPARα and LPL expressions were significantly downregulated (P < 0.05) after treatment with OA-Exos and miR-122 agomir. Levels of proinflammatory mediator TNF-α, NF-κB, and IL-1β were also upregulated in the hepatopancreatic system of grass carp that received intraperitoneal injections of OA-Exos and miR-122 agomir (P < 0.05). These results suggested that the exosome of interest and its miR-122 may promote the occurrence of fatty liver and inflammation, thus laying the foundation for further studies on lipid metabolism and immune regulation of exosomes in fish.