A selective estrogen receptor α agonist ameliorates hepatic steatosis in the male aromatase knockout mouse

Male aromatase knockout mice (ArKO; an estrogen-deficient model) present with male-specific hepatic steatosis that is reversible upon 17β-estradiol replacement. This study aims to elucidate which estrogen receptor (ER) subtype, ERα or ERβ, is involved in the regulation of triglyceride (TG) homeostasis in the liver. Nine-month-old male ArKO mice were treated with vehicle, ERα- or ERβ-specific agonists via s.c. injection, daily for 6 weeks. Male ArKO mice treated with ERα agonist had normal liver histology and TG contents compared with vehicle-treated ArKO; omental (gonadal) and infra-renal (visceral) fat pad weights were normalized to those of vehicle-treated wild-type (WT). In contrast, ERβ agonist treatment did not result in the similar reversal of these ArKO phenotypes. In vehicle-treated ArKO mice, hepatic transcript expression of fatty acid synthase (Fasn) and stearoyl-coenzyme A desaturase 1 (key enzymes inde novoFA synthesis) were significantly elevated compared with vehicle-treated WT, but onlyFasnexpression was lowered to WT level after ERα agonist treatment. There were no significant changes in the transcript levels of carnitine palmitoyl transferase 1 (required for transfer of FA residues into the mitochondria for β-oxidation) and sterol regulatory element-binding factor 1c (the upstream regulator ofde novoFA synthesis). We also confirmed by RT-PCR that only ERα is expressed in the mouse liver. There were no changes in hepatic androgen receptor transcript level across all treatment groups. Our data suggest that estrogens act via ERα to regulate TG homeostasis in the ArKO liver. Since the liver, adipose tissue and arcuate nucleus express mainly ERα, estrogens could regulate hepatic functions via peripheral and central pathways.

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Abstract 325: Response Gene to Complement 32 Deficiency Protects Against Hepatic Steatosis by Inhibiting Lipogenesis in Mice

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.35.suppl_1.325 ◽

2015 ◽

Vol 35 (suppl_1) ◽

Author(s):

Xiaobing Cui ◽

Junna Luan ◽

Shiyou Chen

Keyword(s):

Hepatic Steatosis ◽

Fatty Acid Synthase ◽

De Novo ◽

Regulatory Element ◽

In Vitro Study ◽

De Novo Lipogenesis ◽

Dependent Manner ◽

Response Gene ◽

Normal Chow

Hepatic steatosis is associated with obesity due to the increased lipogenesis. Previously, we have found that RGC-32 (response gene to complement 32) deficiency prevents the mice from high-fat diet (HFD)-induced obesity and insulin resistance. The present study was conducted to determine the role of RGC-32 in the control of hepatic steatosis. We observed that hepatic RGC-32 expression was dramatically induced by HFD challenge. RGC-32 knockout (RGC32-/-) mice were resistant to HFD-induced hepatic steatosis. More importantly, hepatic triglyceride contents of RGC32-/- mice were significantly decreased compared with wild-type (WT) controls on both normal chow and HFD. Mechanistically, RGC-32 deficiency decreased expression of lipogenesis-related genes, sterol regulatory element (SRE) binding protein (SREBP)-1c, fatty acid synthase (FAS) and stearoyl-CoA desaturase-1 (SCD1). Our in vitro study showed that RGC-32 knockdown decreased while RGC-32 overexpression increased SCD1 expression in hepatocytes. Deletion or mutation of SRE in the SCD1 promoter abolished the function of RGC-32. These data demonstrate that RGC-32 contributes to HFD-induced hepatic steatosis by facilitating de novo lipogenesis in a SREBP-1c dependent manner. Therefore, RGC-32 may be a novel drug target in the treatment of hepatic steatosis and its related diseases.

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Regulation of the SREBP transcription factors by mTORC1

Biochemical Society Transactions ◽

10.1042/bst0390495 ◽

2011 ◽

Vol 39 (2) ◽

pp. 495-499 ◽

Cited By ~ 42

Author(s):

Caroline A. Lewis ◽

Beatrice Griffiths ◽

Claudio R. Santos ◽

Mario Pende ◽

Almut Schulze

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthase ◽

Target Genes ◽

De Novo ◽

Regulatory Element ◽

Cholesterol Biosynthesis ◽

Mammalian Target Of Rapamycin ◽

Lipid Biosynthesis ◽

De Novo Lipogenesis ◽

Genes Encoding

In recent years several reports have linked mTORC1 (mammalian target of rapamycin complex 1) to lipogenesis via the SREBPs (sterol-regulatory-element-binding proteins). SREBPs regulate the expression of genes encoding enzymes required for fatty acid and cholesterol biosynthesis. Lipid metabolism is perturbed in some diseases and SREBP target genes, such as FASN (fatty acid synthase), have been shown to be up-regulated in some cancers. We have previously shown that mTORC1 plays a role in SREBP activation and Akt/PKB (protein kinase B)-dependent de novo lipogenesis. Our findings suggest that mTORC1 plays a crucial role in the activation of SREBP and that the activation of lipid biosynthesis through the induction of SREBP could be part of a regulatory pathway that co-ordinates protein and lipid biosynthesis during cell growth. In the present paper, we discuss the increasing amount of data supporting the potential mechanisms of mTORC1-dependent activation of SREBP as well as the implications of this signalling pathway in cancer.

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Arazyme Suppresses Hepatic Steatosis and Steatohepatitis in Diet-Induced Non-Alcoholic Fatty Liver Disease-Like Mouse Model

International Journal of Molecular Sciences ◽

10.3390/ijms20092325 ◽

2019 ◽

Vol 20 (9) ◽

pp. 2325 ◽

Cited By ~ 2

Author(s):

Hua Li ◽

Wonbeak Yoo ◽

Hye-Mi Park ◽

Soo-Youn Lim ◽

Dong-Ha Shin ◽

...

Keyword(s):

Fatty Acid ◽

Liver Disease ◽

Fatty Liver ◽

Hepatic Steatosis ◽

Fatty Liver Disease ◽

Fatty Acid Synthase ◽

Regulatory Element ◽

Diet Group ◽

Alcoholic Fatty Liver ◽

Alcoholic Fatty Liver Disease

Arazyme, a metalloprotease from the spider Nephila clavata, exerts hepatoprotective activity in CCL4-induced acute hepatic injury. This study investigated the hepatoprotective effects in high-fat diet (HFD)-induced non-alcoholic fatty liver disease-like C57BL/6J mice. The mice were randomly divided into four groups (n = 10/group): the normal diet group, the HFD group, the arazyme group (HFD with 0.025% arazyme), and the milk thistle (MT) group (HFD with 0.1% MT). Dietary supplementation of arazyme for 13 weeks significantly lowered plasma triglyceride (TG) and non-esterified fatty acid levels. Suppression of HFD-induced hepatic steatosis in the arazyme group was caused by the reduced hepatic TG and total cholesterol (TC) contents. Arazyme supplementation decreased hepatic lipogenesis-related gene expression, sterol regulatory element-binding transcription protein 1 (Srebf1), fatty acid synthase (Fas), acetyl-CoA carboxylase 1 (Acc1), stearoyl-CoA desaturase-1 (Scd1), Scd2, glycerol-3-phosphate acyltransferase (Gpam), diacylglycerol O-acyltransferase 1 (Dgat1), and Dgat2. Arazyme directly reduced palmitic acid (PA)-induced TG accumulation in HepG2 cells. Arazyme suppressed macrophage infiltration and tumor necrosis factor α (Tnfa), interleukin-1β (Il1b), and chemokine-ligand-2 (Ccl2) expression in the liver, and inhibited secretion of TNFα and expression of inflammatory mediators, Tnfa, Il1b, Ccl2, Ccl3, Ccl4, and Ccl5, in PA-induced RAW264.7 cells. Arazyme effectively protected hepatic steatosis and steatohepatitis by inhibiting SREBP-1-mediated lipid accumulation and macrophage-mediated inflammation.

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Phloretin ameliorates hepatic steatosis through regulation of lipogenesis and Sirt1/AMPK signaling in obese mice

Cell & Bioscience ◽

10.1186/s13578-020-00477-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Chian-Jiun Liou ◽

Shu-Ju Wu ◽

Szu-Chuan Shen ◽

Li-Chen Chen ◽

Ya-Ling Chen ◽

...

Keyword(s):

Oleic Acid ◽

Fatty Acid ◽

Hepatic Steatosis ◽

Lipid Accumulation ◽

Hepg2 Cells ◽

Fatty Acid Synthase ◽

Regulatory Element ◽

Liver Lipid ◽

Obese Mice ◽

Alcoholic Fatty Liver

Abstract Background Phloretin is isolated from apple trees and could increase lipolysis in 3T3-L1 adipocytes. Previous studies have found that phloretin could prevent obesity in mice. In this study, we investigated whether phloretin ameliorates non-alcoholic fatty liver disease (NAFLD) in high-fat diet (HFD)-induced obese mice, and evaluated the regulation of lipid metabolism in hepatocytes. Methods HepG2 cells were treated with 0.5 mM oleic acid to induce lipid accumulation, and then treated with phloretin to evaluate the molecular mechanism of lipogenesis. In another experiment, male C57BL/6 mice were fed normal diet or HFD (60% fat, w/w) for 16 weeks. After the fourth week, mice were treated with or without phloretin by intraperitoneal injection for 12 weeks. Results Phloretin significantly reduced excessive lipid accumulation and decreased sterol regulatory element-binding protein 1c, blocking the expression of fatty acid synthase in oleic acid-induced HepG2 cells. Phloretin increased Sirt1, and phosphorylation of AMP activated protein kinase to suppress acetyl-CoA carboxylase expression, reducing fatty acid synthesis in hepatocytes. Phloretin also reduced body weight and fat weight compared to untreated HFD-fed mice. Phloretin also reduced liver weight and liver lipid accumulation and improved hepatocyte steatosis in obese mice. In liver tissue from obese mice, phloretin suppressed transcription factors of lipogenesis and fatty acid synthase, and increased lipolysis and fatty acid β-oxidation. Furthermore, phloretin regulated serum leptin, adiponectin, triglyceride, low-density lipoprotein, and free fatty acid levels in obese mice. Conclusions These findings suggest that phloretin improves hepatic steatosis by regulating lipogenesis and the Sirt-1/AMPK pathway in the liver.

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Cholesterol biosynthesis supports the growth of hepatocarcinoma lesions depleted of fatty acid synthase in mice and humans

Gut ◽

10.1136/gutjnl-2018-317581 ◽

2019 ◽

Vol 69 (1) ◽

pp. 177-186 ◽

Cited By ~ 20

Author(s):

Li Che ◽

Wenna Chi ◽

Yu Qiao ◽

Jie Zhang ◽

Xinhua Song ◽

...

Keyword(s):

Fatty Acid ◽

Cell Lines ◽

Knockout Mice ◽

Fatty Acid Synthase ◽

De Novo ◽

Therapeutic Option ◽

Regulatory Element ◽

Cholesterol Biosynthesis ◽

Dominant Negative ◽

Comparative Genomic

ObjectiveIncreased de novo fatty acid (FA) synthesis and cholesterol biosynthesis have been independently described in many tumour types, including hepatocellular carcinoma (HCC).DesignWe investigated the functional contribution of fatty acid synthase (Fasn)-mediated de novo FA synthesis in a murine HCC model induced by loss of Pten and overexpression of c-Met (sgPten/c-Met) using liver-specificFasnknockout mice. Expression arrays and lipidomic analysis were performed to characterise the global gene expression and lipid profiles, respectively, of sgPten/c-Met HCC from wild-type andFasnknockout mice. Human HCC cell lines were used for in vitro studies.ResultsAblation ofFasnsignificantly delayed sgPten/c-Met-driven hepatocarcinogenesis in mice. However, eventually, HCC emerged inFasnknockout mice. Comparative genomic and lipidomic analyses revealed the upregulation of genes involved in cholesterol biosynthesis, as well as decreased triglyceride levels and increased cholesterol esters, in HCC from these mice. Mechanistically, loss ofFasnpromoted nuclear localisation and activation of sterol regulatory element binding protein 2 (Srebp2), which triggered cholesterogenesis. Blocking cholesterol synthesis via the dominant negative form of Srebp2 (dnSrebp2) completely prevented sgPten/c-Met-driven hepatocarcinogenesis inFasnknockout mice. Similarly, silencing ofFASNresulted in increasedSREBP2activation and hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase (HMGCR)expression in human HCC cell lines. Concomitant inhibition of FASN-mediated FA synthesis and HMGCR-driven cholesterol production was highly detrimental for HCC cell growth in culture.ConclusionOur study uncovers a novel functional crosstalk between aberrant lipogenesis and cholesterol biosynthesis pathways in hepatocarcinogenesis, whose concomitant inhibition might represent a therapeutic option for HCC.

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Coumarin attenuates hepatic steatosis by down-regulating lipogenic gene expression in mice fed a high-fat diet

British Journal Of Nutrition ◽

10.1017/s0007114512005260 ◽

2013 ◽

Vol 109 (9) ◽

pp. 1590-1597 ◽

Cited By ~ 23

Author(s):

Min Young Um ◽

Mi Kyeong Moon ◽

Jiyun Ahn ◽

Tae Youl Ha

Keyword(s):

Gene Expression ◽

Hepatic Steatosis ◽

High Fat Diet ◽

Fatty Acid Synthase ◽

Binding Protein ◽

Regulatory Element ◽

Thiobarbituric Acid Reactive Substance ◽

High Fat ◽

Lipogenic Gene ◽

Lipogenic Gene Expression

Coumarin is a natural compound abundant in plant-based foods such as citrus fruits, tomatoes, vegetables and green tea. Although coumarin has been reported to exhibit anti-coagulant, anti-inflammation and cholesterol-lowering properties, the effect of coumarin on hepatic lipid metabolism remains unclear. In the present study, we evaluated the ability of coumarin to protect against hepatic steatosis associated with a high-fat diet (HFD) and investigated potential mechanisms underlying this effect. C57BL/6J mice were fed a normal diet, HFD and HFD containing 0·05 % courmarin for 8 weeks. The present results showed that coumarin reduced weight gain and abdominal fat mass in mice fed the HFD for 8 weeks (P< 0·05). Coumarin also significantly reduced the HFD-induced elevation in total cholesterol, apoB, leptin and insulin (P< 0·05). In the liver of HFD-fed mice, coumarin significantly reduced total lipids, TAG and cholesterol (38, 22 and 9 % reductions, respectively; P< 0·05), as well as lipid droplet number and size. Additionally, thiobarbituric acid-reactive substance levels, as an indicator of hepatic steatosis, were attenuated by coumarin (P< 0·05). Finally, coumarin suppressed the HFD-induced up-regulation in fatty acid synthase (FAS) activity, and the expression of sterol regulatory element-binding protein-1, FAS, acetyl-CoA carboxylase 1, PPARγ and CCAAT/enhancer-binding protein-α in the liver. Taken together, these results demonstrate that coumarin could prevent HFD-induced hepatic steatosis by regulating lipogenic gene expression, suggesting potential targets for preventing hepatic steatosis.

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Ishige okamurae Extract Suppresses Obesity and Hepatic Steatosis in High Fat Diet-Induced Obese Mice

Nutrients ◽

10.3390/nu10111802 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1802 ◽

Cited By ~ 10

Author(s):

Young-Jin Seo ◽

Kippeum Lee ◽

Ji-Hyeon Song ◽

Sungwoo Chei ◽

Boo-Yong Lee

Keyword(s):

Fatty Acid ◽

Hepatic Steatosis ◽

High Fat Diet ◽

Fatty Acid Synthase ◽

Metabolic Diseases ◽

Binding Protein ◽

Regulatory Element ◽

Hormone Sensitive Lipase ◽

High Fat ◽

Ishige Okamurae

Obesity is caused by the expansion of white adipose tissue (WAT), which stores excess triacylglycerol (TG), this can lead to disorders including type 2 diabetes, atherosclerosis, metabolic diseases. Ishige okamurae extract (IOE) is prepared from a brown alga and has anti-oxidative properties. We investigated the detailed mechanisms of the anti-obesity activity of IOE. Treatment with IOE blocked lipid accumulation by reducing expression of key adipogenic transcription factors, such as CCAAT/enhancer-binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ), in 3T3-L1 cells. Administration of IOE to high fat diet (HFD)-fed mice inhibited body and WAT mass gain, attenuated fasting hyperglycemia and dyslipidemia. The obesity suppression was associated with reductions in expression of adipogenic proteins, such as C/EBPα and PPARγ, increases in expression of lipolytic enzymes, such as adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), in WAT of HFD-fed mice. In addition, IOE-treated mice had lower hepatic TG content, associated with lower protein expression of lipogenic genes, such as diglyceride acyltransferase 1 (DGAT1), sterol regulatory element-binding protein 1 (SREBP1), fatty acid synthase (FAS). IOE treatment also reduced serum free fatty acid concentration, probably through the upregulation of β-oxidation genes, suggested by increases in AMPKα and CPT1 expression in WAT and liver. In summary, IOE ameliorates HFD-induced obesity and its related metabolic disease, hepatic steatosis, by regulating multiple pathways.

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Estrogen receptor-α signaling maintains immunometabolic function in males and is obligatory for exercise-induced amelioration of nonalcoholic fatty liver

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00259.2018 ◽

2019 ◽

Vol 316 (2) ◽

pp. E156-E167 ◽

Cited By ~ 10

Author(s):

Nathan C. Winn ◽

Thomas J. Jurrissen ◽

Zachary I. Grunewald ◽

Rory P. Cunningham ◽

Makenzie L. Woodford ◽

...

Keyword(s):

Estrogen Receptor ◽

Adipose Tissue ◽

Protein Expression ◽

Hepatic Steatosis ◽

Estrogen Receptor Α ◽

Male Mice ◽

Inflammatory Gene ◽

Gene Transcripts ◽

Exercise Induced ◽

Lower Expression

The role of estrogen receptor-α (ERα) signaling in immunometabolic function is established in females. However, its necessity in males, while appreciated, requires further study. Accordingly, we first determined whether lower metabolic function in male mice compared with females is related to reduced ERα expression. ERα protein expression in metabolically active tissues was lower in males than in females, and this lower expression was associated with worse glucose tolerance. Second, we determined whether ERα is required for optimal immunometabolic function in male mice consuming a chow diet. Despite lower expression of ERα in males, its genetic ablation (KO) caused an insulin-resistant phenotype characterized by enhanced adiposity, glucose intolerance, hepatic steatosis, and metaflammation in adipose tissue and liver. Last, we determined whether ERα is essential for exercise-induced metabolic adaptations. Twelve-week-old wild-type (WT) and ERα KO mice either remained sedentary (SED) or were given access to running wheels (WR) for 10 wk while fed an obesogenic diet. Body weight and fat mass were lower in WR mice regardless of genotype. Daily exercise obliterated immune cell infiltration and inflammatory gene transcripts in adipose tissue in both genotypes. In the liver, however, wheel running suppressed hepatic steatosis and inflammatory gene transcripts in WT but not in KO mice. In conclusion, the present findings indicate that ERα is required for optimal immunometabolic function in male mice despite their reduced ERα protein expression in metabolically active tissues. Furthermore, for the first time, we show that ERα signaling appears to be obligatory for exercise-induced prevention of hepatic steatosis.

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PPARγ2 regulates lipogenesis and lipid accumulation in steatotic hepatocytes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00513.2004 ◽

2005 ◽

Vol 288 (6) ◽

pp. E1195-E1205 ◽

Cited By ~ 241

Author(s):

Susan E. Schadinger ◽

Nancy L. R. Bucher ◽

Barbara M. Schreiber ◽

Stephen R. Farmer

Keyword(s):

Fatty Acid ◽

Cell Line ◽

Lipid Accumulation ◽

Fatty Acid Synthase ◽

Molecular Mechanisms ◽

De Novo ◽

Binding Protein ◽

Regulatory Element ◽

Fatty Acid Binding ◽

Triacylglycerol Synthesis

Peroxisome proliferator-activated receptor-γ (PPARγ) is considered to be one of the master regulators of adipocyte differentiation. PPARγ2 is abundantly expressed in mature adipocytes and is elevated in the livers of animals that develop fatty livers. The aim of this study was to determine the ability of PPARγ2 to induce lipid accumulation in hepatocytes and to delineate molecular mechanisms driving this process. The hepatic cell line AML-12 was used to generate a cell line stably expressing PPARγ2. Oil Red O staining revealed that PPARγ2 induces lipid accumulation in hepatocytes. This phenotype is accompanied by a selective upregulation of several adipogenic and lipogenic genes including adipose differentiation-related protein (ADRP), adipocyte fatty acid-binding protein 4, sterol regulatory element-binding protein-1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase, genes whose expression levels are known to increase in steatotic livers of ob/ob mice. Furthermore, the PPARγ2-regulated induction of both SREBP-1 and FAS parallels an increase in de novo triacylglycerol synthesis in hepatocytes. Triacylglycerol synthesis and lipid accumulation are further enhanced by culturing hepatocytes with troglitazone in the absence of exogenous lipids. These results correspond with an increase in the lipid droplet protein, ADRP, and the data demonstrate that ADRP functions to coat lipid droplets in hepatocytes as observed by confocal microscopy. Taken together, these observations propose a role for PPARγ2 as an inducer of steatosis in hepatocytes and suggest that this phenomenon occurs through an induction of pathways regulating de novo lipid synthesis.

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Inhibition of ADORA1 attenuates hepatic steatosis by gut microbiota-derived acetic acid from Astragalus polysaccharides

10.1101/639195 ◽

2019 ◽

Author(s):

Ying Hong ◽

Ningning Zheng ◽

Xuyun He ◽

Jing Zhong ◽

Junli Ma ◽

...

Keyword(s):

Acetic Acid ◽

Fatty Acid ◽

Gut Microbiota ◽

Hepatic Steatosis ◽

Fatty Acid Synthase ◽

De Novo ◽

Critical Role ◽

Gut Dysbiosis

AbstractGut dysbiosis contributes to nonalcoholic fatty liver disease (NAFLD) formation. However, the underlying molecular mechanism is not fully understood. Here, we report a novel therapeutic target for NAFLD, the hepatic adenosine receptor A1 (ADORA1) that is inhibited by gut microbiota-derived acetic acid from Astragalus polysaccharides (APS). APS supplement attenuated hepatic steatosis by reversing gut dysbiosis in high-fat diet fed mice, and reduced hepatic ADORA1 expression. Patients with hepatic steatosis showed increased expression of hepatic ADORA1, and specific ADORA1 antagonist ameliorated hepatic steatosis as well. Meanwhile, the metabolic benefits of APS were microbiota-dependent due to the production of acetic acid, which improved hepatic steatosis by suppressing ADORA1 both in vitro and in vivo resulting to the inhibition of rate-limiting enzyme for fatty acid de novo synthesis, fatty acid synthase. Our results highlight the critical role of gut microbiota-acetic acid-hepatic ADORA1 axis in NAFLD development and reveal the novel mechanism underlying the metabolic benefits of APS.

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