Hepatic Metabolic Disorders Research Articles

MiR-552-3p modulates transcriptional activities of FXR and LXR to ameliorate hepatic glycolipid metabolism disorder

The nuclear location of miRNAs has been known for more than a decade, but the exact function of miRNAs in the nucleus has not been fully elucidated. We previously discovered that intranuclear miR-552-3p has an inhibitory role on gene transcription and contains a particular AGGTCA-like sequence, the cis-elements of the NR1 subfamily of nuclear receptors. Here, we aim to explore the potential effect of miR-552-3p and its AGGTCA-like sequence on NR1s and its possible application in improving hepatic glycolipid metabolism. RNA-seq, mass spectrometry, and bioinformatics analysis were used to reveal the possible pathways influenced by miR-552-3p. High fat-high fructose diet-fed mice and db/db mice transfected with AAV2/8-miR-552-3p were established to investigate the invivo effects of miR-552-3p on hepatic glycolipid metabolism. Fluorescence resonance energy transfer, pull-down, electrophoretic mobility shift, and chromatin immunoprecipitation assays were performed to explore the mechanism by which miR-552-3p regulates NR1s. RT-PCR was conducted to analyse miR-552-3p levels in liver biopsies from patients with NAFLD and normal controls. MiR-552-3p could inhibit metabolic gene expression invitro and displayed beneficial effects on glycolipid metabolism invivo. Intranuclear miR-552-3p primarily regulated the LXRα and FXR pathways; this was achieved by its binding to the complementary sequence of AGGTCA to modulate the transcriptional activities of LXRα and FXR. Moreover, LXRα and FXR ligands could restore the effects of miR-552-3p on gene expression and glycolipid metabolism. Additionally, the hepatic miR-552-3p level was significantly decreased in liver samples from patients with NAFLD compared to normal controls. The mechanism by which miR-552-3p modulates LXRα and FXR has revealed a new method of miRNA-mediated gene regulation. In addition, the beneficial effects invivo and clinical relevance of miR-552-3p suggest that it might be a potential therapeutic target for the treatment of glycolipid metabolic disease. Glycolipid metabolic diseases, which have become a major public health concern worldwide, are triggered by abnormalities in lipid and glucose metabolism. Herein, we show that miR-552-3p has the ability to ameliorate hepatic glycolipid metabolic diseases by modulating the transcriptional activities of LXRα and FXR in the nucleus. These findings provide evidence that miR-552-3p may serve as a potential therapeutic target.

The Evolution of Gene Therapy in the Treatment of Metabolic Liver Diseases.

Monogenic metabolic disorders of hepatic origin number in the hundreds, and for many, liver transplantation remains the only cure. Liver-targeted gene therapy is an attractive treatment modality for many of these conditions, and there have been significant advances at both the preclinical and clinical stages. Viral vectors, including retroviruses, lentiviruses, adenovirus-based vectors, adeno-associated viruses and simian virus 40, have differing safety, efficacy and immunogenic profiles, and several of these have been used in clinical trials with variable success. In this review, we profile viral vectors and non-viral vectors, together with various payloads, including emerging therapies based on RNA, that are entering clinical trials. Genome editing technologies are explored, from earlier to more recent novel approaches that are more efficient, specific and safe in reaching their target sites. The various curative approaches for the multitude of monogenic hepatic metabolic disorders currently at the clinical development stage portend a favorable outlook for this class of genetic disorders.

Sirtuin 3-mediated deacetylation of acyl-CoA synthetase family member 3 by protocatechuic acid attenuates non-alcoholic fatty liver disease.

Hepatic fatty acid metabolism disorder, a key pathogenic mechanism underlying non-alcoholic fatty liver disease (NAFLD), is associated with the hyperacetylation of mitochondrial enzymes. Acyl-CoA synthetase family member 3 (ACSF3), which is involved in the regulation of fatty acid metabolism, was predicted to contain lysine acetylation sites related to the mitochondrial deacetylase sirtuin 3 (SIRT3). The purpose of this study was to explore the underlying mechanism by which SIRT3 deacetylates ACSF3 in NAFLD and the protective effect of the natural phenolic compound protocatechuic acid (PCA) against fatty acid metabolism disorder via the SIRT3/ACSF3 pathway. The role of protocatechuic acid and its molecular mechanism in NAFLD were detected in rats and SIRT3-knockout mice fed a high-fat diet (HFD) and in AML-12 cells treated with palmitic acid (PA). Pharmacological treatment with protocatechuic acid significantly attenuated high-fat diet-induced fatty acid metabolism disorder in NAFLD. Molecular docking assays showed that protocatechuic acid specifically bound SIRT3 as a substrate and increased SIRT3 protein expression. However, the protective role of protocatechuic acid was abolished by SIRT3 knockdown, which increased ACSF3 expression and exacerbated fatty acid metabolism disorder. Mechanistically, SIRT3 was shown to specifically regulate the acetylation and degradation of ACSF3, which govern the capacity of ACSF3 to mediate fatty acid metabolism disorder during NAFLD. SIRT3-mediated ACSF3 deacetylation is a novel molecular mechanism in NAFLD therapy and protocatechuic acid confers protection against high-fat diet- and palmitic acid-induced hepatic fatty acid metabolism disorder through the SIRT3/ACSF3 pathway.

Soluble Klotho Improves Hepatic Glucose and Lipid Homeostasis in Type 2 Diabetes

Type 2 diabetes (T2D) is one of the most escalating global metabolic diseases, which is highly associated with insulin resistance (IR) and risk of combination with nonalcoholic fatty liver disease (NAFLD). Previous studies suggest that soluble klotho (sKL) could serve as a circulating hormone to mediate energy metabolism, but the detailed mechanism is poorly understood. In this study, we generated T2D models of wild-type (WT), sKL heterozygous (KL+/−), and sKL transgenic (TgKL) mice continuously fed a high-fat diet (HFD) and constructed L02 cell lines that stably overexpress sKL to investigate the effect of sKL on hepatic glucose and lipid metabolism. Surprisingly, we discovered that sKL deficiency resulted in exacerbated diabetic phenotypes and hepatic glucolipid metabolism disorders in HFD-fed KL+/− diabetic mice (KL+/− DM), whereas TgKL diabetic mice (TgKL DM) exhibited ameliorated diabetic phenotypes and decreased IR. Mechanistic studies in vitro and in vivo demonstrated that sKL could inhibit the PI3K/AKT/mTORC1 signaling to upregulate peroxisome proliferator-activated receptor α (PPARα) expression by directly interacting with type 1 insulin-like growth factor receptor (IGF1R) in HFD-fed T2D mice. Thus, sKL could improve hepatic glucolipid homeostasis to ameliorate diabetic phenotypes and lipid accumulation and may function as a potential therapeutic target for the treatment of T2D and reduce the risk of NAFLD.

Assessing the potential value of Rosa Roxburghii Tratt in arsenic-induced liver damage based on elemental imbalance and oxidative damage.

Environmental exposure to arsenic is a major public health challenge worldwide. Growing evidence indicates that coal-burning arsenic can cause hepatic oxidative damage. However, the value of Rosa roxburghii Tratt (RRT) with antioxidant properties on arsenic-caused hepatic oxidative damage has never been elucidated yet. In this study, the animals were exposed to coal-burning arsenic (10mg/kgbw) for 90days and the result showed a loss of body weight, impaired liver function and liver diseases, increased hepatic oxidative damage and metabolic disorder of multiple elements including selenium, copper, zinc which were related to synthesis of antioxidant enzymes. Another finding is that RRT restored the abnormal liver function and alleviated the procedures of liver diseases of arsenic poisoning rats. In addition, it could also effectively reduce the degree of oxidative damage in serum and liver, and restore the activity of some antioxidant enzymes. Importantly, RRT reversed the content of most disordered elements caused by arsenic in liver and reduced the excretion of several essential elements in urine, including selenium, copper and zinc. Our study provides some limited evidence that RRT can alleviate coal-burning arsenic-induced liver damage induced by regulating elemental metabolic disorders and liver oxidation and antioxidant balance. The study provides a scientific basis for further studies of the causes of the arsenic-induced liver damage, and effective intervention strategies.

Sub-chronic carbendazim exposure induces hepatic glycolipid metabolism disorder accompanied by gut microbiota dysbiosis in adult zebrafish (Daino rerio)

Carbendazim (CBZ) as a broad spectrum fungicide is widely used in the whole world to contorl plant diseases. With the application of CBZ in the agriculture, it has been detected in vegetables and fruits. Nowadays, it even has been detected in the watercourse and indoor dust. However, the toxic effects of CBZ on aquatic organisms have received limited attention. In this study, male adult zebrafish were exposed at 0, 30 and 100 μg/L CBZ for 21 days to assess its effects on hepatic glycolipid metabolism. After exposure, the body weight and length decreased, but the condition factor increased significantly. Some hepatic biochemical parameters including the levels of glucose, pyruvate, low density lipoprotein (LDL) and triglyceride (TG) decreased significantly in the liver of zebrafish after exposure with CBZ. Two transaminases alanine transaminase (ALT) and aspartate transaminase (AST) also increased significantly, indicating that subchronic CBZ exposure influenced the liver function. Moreover, the relative mRNA levels of some key genes related to the glycolysis and lipid metabolism in the liver also changed significantly. Furthermore, the transcriptome analysis showed that the carbon metabolism, lipid metabolism and detoxification metabolism were also affected in the liver of CBZ exposed zebrafish. Interestingly, we also found the amounts of the Firmicutes, Bacteroidetes, Actinobacteria, α-Proteobacteria, γ-Proteobacteria and Verrucomicrobia at phylum level significantly decreased in the gut. Sequencing V3-V4 region of 16S rRNA also demonstrated gut microbiota composition changed significantly according to weighted UniFrac distance analysis. Consequently, subchronic CBZ exposure induced hepatic metabolic disorder accompanied by gut microbiota dysbiosis in adult male zebrafish.

Proteome characteristics of liver tissue from patients with parenteral nutrition-associated liver disease

BackgroundParenteral nutrition (PN)-associated liver disease (PNALD) is a common and life-threatening complication in patients receiving PN. However, its definitive etiology is not yet clear. Therefore, performed proteomic analyses of human liver tissue to explore the same.MethodsLiver tissue was derived and compared across selected patients with (n = 3) /without (n = 4) PNALD via isobaric Tag for Relative and Absolute Quantitation (iTRAQ)-based quantitative proteomics. Bioinformatics analysis was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases to explore the mechanisms of PNALD based on differentially expressed proteins (DEPs). The essential proteins that were differentially expressed between the two groups were explored and verified by western blotting.ResultsA total of 112 proteins were found to be differentially expressed, of which 73 were downregulated, and 39 were upregulated in the PNALD group. Bioinformatics analysis showed DEPs to be associated with mitochondrial oxidative phosphorylation (mainly involved in mitochondrial respiratory chain complex I assembly), hepatic glycolipid metabolism (involved primarily in glycogen formation and gluconeogenesis), and oxidative stress (mainly involved in antioxidant change).ConclusionOverall, our results indicated that mitochondrial energy metabolism impairment, hepatic glycolipid metabolism disorder, and excessive oxidative stress injury might explain the comprehensive mechanism underlying PNALD. Moreover, we have provided multiple potential targets for further exploring the PNALD mechanism.

1854-P: Kcnh6 Improves Glucose Metabolism by Inhibiting Oxidative Stress

Mitochondria plays an important role in maintaining intracellular Ca2+homeostasis, and its defects may be responsible for disorders in glucose metabolism and type 2 diabetes (T2D). Mitochondrial Ca2+overload causes superoxide production and functional impairment, culminating in apoptosis. In previous studies, we first demonstrated that Kcnh6 knockout mice exhibited impaired glucose tolerance or diabetes. However, the precise role of Kcnh6 on glucose metabolism remains unknown. Here, we show that Kcnh6 can improve glucose metabolism in the liver. Kcnh6 increases glucose uptake and decreases glycogen synthesis in the liver accompanied by increased expression of glucose transporters, insulin receptor substrates and decreased expression of enzymes for glycogen synthesis. Kcnh6knockout mice display elevated levels of oxidative stress accompanied by increased mitochondrial and intracellular ROS and calcium. As a result of anti-oxidative stress, Kcnh6 improves hepatic glucose metabolism disorder through the JNK and p38MAPKsignaling pathways. In summary, Kcnh6 can improve hepatic glucose metabolism by regulating mitochondrial Ca2+and Inhibiting oxidative stress. As in glucose metabolism in the liver is considered to be the primary cause of the development of T2D, Kcnh6 may serve as a new diabetes target. Disclosure J. Lu: None. L. Zhang: None. T. Shi: None. Funding National Key Research and Development Program of China (2017YFC0909600); National Natural Science Foundation of China (81800688); Beijing Municipal Administration of Hospitals Incubating Program (PX2019006)

Metabolomic profiling of goslings with visceral gout reveals a distinct metabolic signature

ABSTRACT 1.The objective of the experiment was to analyse serum profiles of goslings with visceral gout and compare them with those of healthy individuals to identify differentially-abundant metabolites as potential biomarkers. 2.Untargeted gas chromatography and time-of-flight mass spectrometry (GC-TOF-MS) metabolomic profiling was used to compare the serum metabolome of 15 goslings (Anser cygnoides) with gout and 15 healthy goslings (control). 3.Goslings with gout had a metabolic profile distinct from that of the controls, with 45 metabolite levels differing significantly (VIP > 1; P < 0.05) between both groups. Nine metabolites (hydrocortisone, glucose, trans-4-hydroxy-L-proline, galactose, 2-deoxy-D-galactose, beta-mannosylglycerate, d-glucoheptose, zymosterol, and hypoxanthine) were selected through receiver operating characteristics (ROC) analysis (area under curve (AUC) score ≥0.85) as potential biomarkers. Pathway analysis revealed that metabolites with differing levels were mainly involved in galactose, arginine and proline and purine metabolisms. 4.These results provided new insights into the pathogenesis of gout. Increased xanthine and hypoxanthine with decreased hydrocortisone provide promising biomarkers for gosling gout diagnosis. The findings suggested that hepatic metabolic disorders frequently occur in the development of avian gout.

Sex-dependent effects of ambient PM2.5 pollution on insulin sensitivity and hepatic lipid metabolism in mice

Background & aimsEmerging evidence supports ambient fine particulate matter (PM2.5) exposure is associated with insulin resistance (IR) and hepatic lipid accumulation. In this study, we aimed to evaluate the sex-dependent vulnerability in response to PM2.5 exposure and investigate the underlying mechanism by which PM2.5 modulates hepatic lipid metabolism.MethodsBoth male and female C57BL/6 mice were randomly assigned to ambient PM2.5 or filtered air for 24 weeks via a whole body exposure system. High-coverage quantitative lipidomics approaches and liquid chromatography-mass spectrometry techniques were performed to measure hepatic metabolites and hormones in plasma. Metabolic studies, histological analyses, as well as gene expression levels and molecular signal transduction analysis were applied to examine the effects and mechanisms by which PM2.5 exposure-induced metabolic disorder.ResultsFemale mice were more susceptible than their male counterparts to ambient PM2.5 exposure-induced IR and hepatic lipid accumulation. The hepatic lipid profile was changed in response to ambient PM2.5 exposure. Levels of hepatic triacylglycerols (TAGs), free fatty acids (FFAs) and cholesterol were only increased in female mice from PM group compared to control group. Plasmalogens were dysregulated in the liver from PM2.5-exposed mice as well. In addition, exposure to PM2.5 led to enhanced hepatic ApoB and microsomal triglyceride transport protein expression in female mice. Finally, PM2.5 exposure inhibited hypothalamus-pituitary-adrenal (HPA) axis and decreased glucocorticoids levels, which may contribute to the vulnerability in PM2.5-induced metabolic dysfunction.ConclusionsAmbient PM2.5 exposure inhibited HPA axis and demonstrated sex-associated differences in its effects on IR and disorder of hepatic lipid metabolism. These findings provide new mechanistic evidence of hormone regulation in air pollution-mediated metabolic abnormalities of lipids and more personalized care should be considered in terms of sex-specific risk factors.

Defects in mTORC1 Network and mTORC1-STAT3 Pathway Crosstalk Contributes to Non-inflammatory Hepatocellular Carcinoma.

Background and AimsMammalian target of rapamycin complex 1 (mTORC1) is frequently hyperactivated in hepatocellular carcinoma (HCC). Cases of HCC without inflammation and cirrhosis are not rarely seen in clinics. However, the molecular basis of non-inflammatory HCC remains unclear.MethodsSpontaneous non-inflammatory HCC in mice was triggered by constitutive elevation of mTORC1 by liver-specific TSC1 knockout (LTsc1KO). A multi-omics approach was utilized on tumor tissues to better understand the molecular basis for the development of HCC in the LTsc1KO model.ResultsWe showed that LTsc1KO in mice triggered spontaneous non-inflammatory HCC, with molecular characteristics similar to those of diethylnitrosamine-mediated non-cirrhotic HCC. Mitochondrial and autophagy defects, as well as hepatic metabolic disorder were manifested in HCC development by LTsc1KO. mTORC1 activation on its own regulated an oncogenic network (DNA-damage-inducible transcript 4, nuclear protein 1, and fibroblast growth factor 21), and mTORC1–signal transducer and activator of transcription pathway crosstalk that altered specific metabolic pathways contributed to the development of non-inflammatory HCC.ConclusionOur findings reveal the mechanisms of mTORC1-driven non-inflammatory HCC and provide insight into further development of a protective strategy against non-inflammatory HCC.

Transcranial sonography changes in patients with Wilson's Disease during de-coppering therapy.

Wilson's Disease (WD) is an inherited disorder of impaired hepatic copper metabolism that leads to copper accumulation in organs such as the liver and brain. Using transcranial sonography (TCS), we investigated brain changes in WD patients during de-coppering treatment. Forty-one consecutive treatment-naïve WD patients were classified as having hepatic (WDh; n = 20) or neurological WD (WDn; n = 21) based on symptoms at diagnosis; all patients received either D-penicillamine or zinc sulfate and were observed for 24 months. TCS was performed at regular intervals from study entry (month 0) to month 24. At study entry, bilateral lenticular nucleus (LN) hyperechogenicity was found in 18 patients with WDn and in nine with WDh (p = 0.006). Substantia nigra (SN) hyperechogenicity was found in nine patients with WDn) and four with WDh (p = ns). After 24 months of treatment, bilateral LN hyperechogenicity was still present in 17 patients with WDn and 14 with WDh (p = ns). SN hyperechogenicity was present in one patient with WDn and two with WDh (p = ns). The decrease in the number of patients with SN hyperechogenicity was significant in the WDn group (p < 0.05). LN hyperechogenicity is the most common TCS abnormality in WD patients, and was observed despite two years of de-coppering treatment. SN hyperechogenicity was less common, and decreased after treatment introduction.

Early Hepatic Gene Expression Profile of Lipid Metabolism of Mice on High Fat Diet after Treatment with Anti‐Obesity Drugs

Obesity is a multifactorial disorder of global scale. The liver plays a vital role in fat metabolism. Disorder of hepatic fat metabolism is associated with obesity and fatty liver disease. This study aimed to detect the effects of anti‐obesity drugs (sulforaphane; SFN and leptin) on hepatic gene expression of fat metabolism in mice that were fed HFD during an early time of DIO.Thirty‐two wild type (WT) ten‐week‐old CD1 male mice were fed high fat diet for four weeks in order to induce diet‐induced obesity (DIO). The mice were treated with a vehicle, or SFN for one week and then each group is treated with leptin or saline for 24 hours. Four groups of treatment were obtained; control group (vehicle + saline), group 2 (vehicle + leptin), group 3 (SFN + saline), and group 4 (SFN + leptin). Body weight and food intake were monitored during the treatment period. Following the treatments, liver tissue was collected, and total RNA was extracted to assess the expression of 84 genes involved in hepatic fat metabolism using RT‐PCR profiler array technique.Leptin treatment upregulated the genes involved in fatty acid beta‐oxidation (Acsbg2, Acsm4) and fatty acyl‐CoA biosynthesis (Acot6, Acsl6), and down‐regulated the fatty acid transport gene (Slc27a2). SFN upregulated acyl‐CoA hydrolase (Acot3) and long chain fatty acid activation for lipids synthesis and beta‐oxidation (Acsl1). Leptin + SFN upregulated fatty acid beta‐oxidation‐related genes (Acad11, Acam) and acyl‐CoA hydrolases (Acot3, Acot7), and downregulated fatty acid elongation gene, Acot2. As a result, treatment with both SFN and leptin has a more profound effect in ameliorating the pathways involved in hepatic lipogenesis and TG accumulation and body weight gain than other types of intervention.We conclude that early intervention of obesity pathogenesis could ameliorate the metabolic changes of fat metabolism in the liver, as observed in mice on HFD in response to SFN anti‐obesity treatment.Support or Funding InformationThis publication was made possible by NPRP Grant No. 9‐351‐3‐075 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. Qatar university grant QUST‐1‐CHS‐2019‐3

Knockdown of long non-coding RNA Gm10804 suppresses disorders of hepatic glucose and lipid metabolism in diabetes with non-alcoholic fatty liver disease.

Deregulated glucose and lipid metabolism are the primary underlying manifestations associated with diabetes mellitus (DM) and non-alcoholic fatty liver disease (NAFLD). This study aims to investigate the role of Gm10804, a novel long non-coding RNA (lncRNA), in regulating hepatic glucose and lipid metabolism in DM complicated with NAFLD (DM-NAFLD). Mouse primary hepatocytes exposed to high glucose (HG) were used as a cell model. A mouse DM-NAFLD model was established by high-energy feeding combined with intraperitoneal injection of streptozotocin. The results showed that Gm10804 expression was upregulated in HG-treated hepatocytes and livers from DM-NAFLD mice. Results in hepatocytes in vitro demonstrated that Gm10804 overexpression aggravated, whereas Gm10804 silencing abrogated HG-induced increase in intracellular triglyceride (TG) content, lipid accumulation and expression of hepatic lipogenic proteins (sterol regulatory element-binding proteins 1-c [SREBP-1c] and fatty acid synthase [FAS]) and enzymes for gluconeogenesis (phosphoenolpyruvate carboxykinase [PEPCK] and glucose-6-phosphatase [G6Pase]). Further in vivo assays showed that lentivirus-mediated hepatic knockdown of Gm10804 alleviated hepatic steatosis and lipid accumulation, and decreased expression of hepatic PEPCK, G6Pase, SREBP-1c and FAS in DM-NAFLD mice. In summary, Gm10804 knockdown attenuates hepatic lipid accumulation by ameliorating disorders of hepatic glucose and lipid metabolism in DM-NAFLD. SIGNIFICANCE OF THE STUDY: We first discovered that Gm10804 knockdown attenuated hepatic lipid accumulation by ameliorating disorders of hepatic glucose and lipid metabolism in DM-NAFLD. These results help to understand the pathogenesis and development of DM-NAFLD and provide some clues for further understanding the regulation of lncRNAs in glucose and lipid metabolism.

Hepatocyte TMEM16A Deletion Retards NAFLD Progression by Ameliorating Hepatic Glucose Metabolic Disorder.

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent form of chronic liver disease, and the mechanisms underpinning its pathogenesis have not been completely established. Transmembrane member 16A (TMEM16A), a component of the Ca2+‐activated chloride channel (CaCC), has recently been implicated in metabolic events. Herein, TMEM16A is shown to be responsible for CaCC activation in hepatocytes and is increased in liver tissues of mice and patients with NAFLD. Hepatocyte‐specific ablation of TMEM16A in mice ameliorates high‐fat diet‐induced obesity, hepatic glucose metabolic disorder, steatosis, insulin resistance, and inflammation. In contrast, hepatocyte‐specific TMEM16A transgenic mice exhibit the opposite phenotype. Mechanistically, hepatocyte TMEM16A interacts with vesicle‐associated membrane protein 3 (VAMP3) to induce its degradation, suppressing the formation of the VAMP3/syntaxin 4 and VAMP3/synaptosome‐associated protein 23 complexes. This leads to the impairment of hepatic glucose transporter 2 (GLUT2) translocation and glucose uptake. Notably, VAMP3 overexpression restrains the functions of hepatocyte TMEM16A in blocking GLUT2 translocation and promoting lipid deposition, insulin resistance, and inflammation. In contrast, VAMP3 knockdown reverses the beneficial effects of TMEM16A downregulation. This study demonstrates a role for TMEM16A in NAFLD and suggests that inhibition of hepatic TMEM16A or disruption of TMEM16A/VAMP3 interaction may provide a new potential therapeutic strategy for NAFLD.

Branched-Chain Amino Acids Exacerbate Obesity-Related Hepatic Glucose and Lipid Metabolic Disorders via Attenuating Akt2 Signaling.

Branched chain amino acids (BCAAs) are associated with the progression of obesity-related metabolic disorders, including type 2 diabetes and nonalcoholic fatty liver disease. However, whether BCAAs disrupt the homeostasis of hepatic glucose and lipid metabolism remains unknown. In this study, we observed that BCAAs supplementation significantly reduced high-fat (HF) diet-induced hepatic lipid accumulation while increasing the plasma lipid levels and promoting muscular and renal lipid accumulation. Further studies demonstrated that BCAAs supplementation significantly increased hepatic gluconeogenesis and suppressed hepatic lipogenesis in HF diet-induced obese (DIO) mice. These phenotypes resulted from severe attenuation of Akt2 signaling via mTORC1- and mTORC2-dependent pathways. BCAAs/branched-chain α-keto acids (BCKAs) chronically suppressed Akt2 activation through mTORC1 and mTORC2 signaling and promoted Akt2 ubiquitin-proteasome-dependent degradation through the mTORC2 pathway. Moreover, the E3 ligase Mul1 played an essential role in BCAAs/BCKAs-mTORC2-induced Akt2 ubiquitin-dependent degradation. We also demonstrated that BCAAs inhibited hepatic lipogenesis by blocking Akt2/SREBP1/INSIG2a signaling and increased hepatic glycogenesis by regulating Akt2/Foxo1 signaling. Collectively, these data demonstrate that in DIO mice, BCAAs supplementation resulted in serious hepatic metabolic disorder and severe liver insulin resistance: insulin failed to not only suppress gluconeogenesis but also activate lipogenesis. Intervening BCAA metabolism is a potential therapeutic target for severe insulin-resistant disease.

The Role of High Fat Diets and Liver Peptidase Activity in the Development of Obesity and Insulin Resistance in Wistar Rats.

High-fat diets (HFD) have been widely associated with an increased risk of metabolic disorders and overweight. However, a high intake of sources that are rich in monounsaturated fatty acids has been suggested as a dietary agent that is able to positively influence energy metabolism and vascular function. The main objective of this study was to analyze the role of dietary fats on hepatic peptidases activities and metabolic disorders. Three diets: standard (S), HFD supplemented with virgin olive oil (VOO), and HFD supplemented with butter plus cholesterol (Bch), were administered over six months to male Wistar rats. Plasma and liver samples were collected for clinical biochemistry and aminopeptidase activities (AP) analysis. The expression of inducible nitric oxide synthase (iNOS) was also determined by Western blot in liver samples. The diet supplement with VOO did not induce obesity, in contrast to the Bch group. Though the VOO diet increased the time that was needed to return to the basal levels of plasma glucose, the fasting insulin/glucose ratio and HOMA2-%B index (a homeostasis model index of insulin secretion and valuation of β-cell usefulness (% β-cell secretion)) were improved. An increase of hepatic membrane-bound dipeptidyl-peptidase 4 (DPP4) activity was found only in VOO rats, even if no differences in fasting plasma glucagon-like peptide 1 (GLP-1) were obtained. Both HFDs induced changes in hepatic pyroglutamyl-AP in the soluble fraction, but only the Bch diet increased the soluble tyrosyl-AP. Angiotensinase activities that are implicated in the metabolism of angiotensin II (AngII) to AngIV increased in the VOO diet, which was in agreement with the higher activity of insulin-regulated-AP (IRAP) in this group. Otherwise, the diet that was enriched with butter increased soluble gamma-glutamyl transferase (GGT) and Leucyl-AP, iNOS expression in the liver, and plasma NO. In summary, VOO increased the hepatic activity of AP that were related to glucose metabolism (DPP4, angiotensinases, and IRAP). However, the Bch diet increased activities that are implicated in the control of food intake (Tyrosine-AP), the index of hepatic damage (Leucine-AP and GGT), and the expression of hepatic iNOS and plasma NO. Taken together, these results support that the source of fat in the diet affects several peptidases activities in the liver, which could be related to alterations in feeding behavior and glucose metabolism.

Triazole fungicides induce hepatic lesions and metabolic disorders in rats

Triazole fungicides induce hepatic lesions and metabolic disorders in rats

Hypertensive Rats Treated Chronically With Nω-Nitro-L-Arginine Methyl Ester (L-NAME) Induced Disorder of Hepatic Fatty Acid Metabolism and Intestinal Pathophysiology.

Nω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) biosynthesis, results in hypertension and liver injury. This study aimed at investigating the changes of liver lipometabonomics and exploring the underlying mechanisms of liver injury in the L-NAME-treated rats. The male Sprague-Dawley (SD) rats were treated with L-NAME (40 mg/kg, p.o.) for 8 weeks. After that, the liver, aorta, fecal, and serum were collected for analysis. The results showed that L-NAME induced hypertension and disordered the endothelial nitric oxide synthase (eNOS)-NO pathway in the treated rats. L-NAME could also increase the levels of serum total cholesterol (TC), triglyceride (TG), alanine transaminase (ALT), and aspartate transaminase (AST). The multidimensional mass spectrometry-based shotgun lipidomics (MDMS-SL) analysis showed that L-NAME could induce significant changes of the total hepatic lipids and most hepatic triglycerides, as well as fatty acid (FA). A positive correlation was found between the blood pressure and TAG. Immunofluorescence and Western-Blot experiments indicated that the L-NAME treatment significantly influenced some FA β-oxidation, desaturation, and synthesis-related proteins. The increase of intestinal inflammation, decrease of microcirculation and tight junction proteins, as well as alterations of microbial communities were observed in the L-NAME induced hypertensive rats, as well as alterations of microbial communities were notable correlation to TAG and FA species. This study demonstrated that the L-NAME-induced hypertensive rats exhibiting liver injury were the joint action of hepatic abnormal fatty acid metabolism and microcirculation disorder. Furthermore, the gut microflora, as well as the changes of FA β-oxidation (ACOX, CPT1α), desaturation (SCD-1), and synthesis (FAS) may be the potential mechanisms for abnormal fatty acid metabolism.

Defects in mTORC1 Network and mTORC1-STAT3 Pathway Crosstalk Contributes to Noninflammatory Hepatocellular Carcinoma

Background & Aims: Mammalian target of rapamycin complex 1 (mTORC1) is frequently hyperactivated in hepatocellular carcinoma (HCC). Cases of HCC without inflammation and cirrhosis are not rarely seen in clinics. However, the molecular basis of noninflammatory HCC remains unclear. Methods: Spontaneous noninflammatory HCC in mice was triggered by constitutive elevation of mTORC1 by liver-specific Tsc1 knockout (LTsc1KO). A multi-omics approach was utilized on tumor tissues to better understand the molecular basis for the development of HCC in the LTsc1KO model. Results: We showed that LTsc1KO in mice triggered spontaneous noninflammatory HCC, with molecular characteristics similar to those of diethylnitrosamine-mediated noncirrhotic HCC. Mitochondrial and autophagy defects, as well as hepatic metabolic disorder were manifested in HCC development by LTsc1KO. mTORC1 activation on its own regulated an oncogenic network (DNA-damage-inducible transcript 4, nuclear protein 1 and fibroblast growth factor 21), and mTORC1–signal transducer and activator of transcription pathway crosstalk that altered specific metabolic pathways contributed to the development of noninflammatory HCC. Conclusion: Our findings reveal the mechanisms of mTORC1-driven noninflammatory HCC and provide insight into further development of a protective strategy against noninflammatory HCC. Funding Statement: This work was supported by the National Key R&D Program of China (2018YFC1106400, 018YFA0108200), Science and Technology Planning Project of Guangdong Province (2015B020229002), the National Natural Science Foundation of China (81470875, 81701580, 81600489), the Natural Science Foundation of Guangdong Province (2014A030312013, 2018A030313128, 2018A030313214), Guangdong key research and development plan (2019B020234003), and Science and Technology Program of Guangzhou (201604020002, 201803010086). Declaration of Interests: The authors declare that they have no competing financial interest to disclose. Ethics Approval Statement: All of the animal experiments were approved by the Animal Ethics Committee of Southern Medical University (approval number SYXK 2011-0074) and performed in accordance with animal ethics guidelines and approved protocols.