scholarly journals MIF-2/D-DT is an atypical atherogenic chemokine that promotes advanced atherosclerosis and hepatic lipogenesis

2021 ◽  
Author(s):  
Omar El Bounkari ◽  
Chunfang Zan ◽  
Jonas Wagner ◽  
Elina Bugar ◽  
Priscila Bourilhon ◽  
...  
Keyword(s):  
B Cell ◽  
Lipid Accumulation ◽  
Vascular Inflammation ◽  
Foam Cell Formation ◽  
Hepatic Lipogenesis ◽  
Lesion Formation ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation

Atherosclerosis is the underlying cause of cardiovascular diseases (CVDs) such as myocardial infarction and ischemic stroke. It is a lipid-triggered chronic inflammatory condition of the arterial vascular wall that is driven by various inflammatory pathways including atherogenic cytokines and chemokines. D-dopachrome tautomerase (D-DT), also known as macrophage migration inhibitory factor-2 (MIF-2), belongs to the MIF protein family, which is best known for its pathogenic role in a variety of inflammatory and immune conditions including CVDs. While MIF is well known as a promoter of atherogenic processes, MIF-2 has not been studied in atherosclerosis. Here, we investigated atherosclerosis in hyperlipidemic Mif-2-/-Apoe-/- mice and studied the role of MIF-2 in various atherogenic assays in vitro. We found that global Mif-2 deficiency as well as its pharmacological blockade by 4-CPPC protected against atherosclerotic lesion formation and vascular inflammation in models of early and advanced atherogenesis. On cellular level, MIF-2 promoted monocyte migration in 2D and 3D and monocyte arrest on aortic endothelial monolayers, promoted B-cell chemotaxis in vitro and B-cell homing in vivo, and increased macrophage foam cell formation. Dose curves and direct comparison in a 3D migration set-up suggest that MIF-2 may be a more potent chemokine than MIF for monocytes and B cells. We identify CXCR4 as a novel receptor for MIF-2. The evidence relies on a CXCR4 inhibitor, CXCR4 internalization experiments, MIF-2/CXCR4 binding studies by yeast-CXCR4 transformants, and fluorescence spectroscopic titrations with a soluble CXCR4 surrogate. Of note, Mif-2-/- Apoe-/- mice exhibited decreased plasma cholesterol and triglyceride levels, lower body weights, smaller livers, and profoundly reduced hepatic lipid accumulation compared to Apoe-/- mice. Mechanistic experiments in Huh-7 hepatocytes suggest that MIF-2 regulates the expression and activation of sterol-regulatory element binding protein-1 and -2 (SREBP-1, SREBP-2) to induce lipogenic downstream genes such as FASN and LDLR, while it attenuated the activation of the SREBP inhibiting AMPK pathway. Studies using receptor Inhibitors showed that SREBP activation and hepatic lipoprotein uptake by MIF-2 is mediated by both CXCR4 and CD74. Lastly and in line with a combined role of MIF-2 in vascular inflammation and hepatic lipid accumulation, MIF-2 was found to be profoundly upregulated in unstable human carotid plaques, underscoring a critical role for MIF-2 in advanced stages of atherosclerosis. Together, these data identify MIF-2 as a novel atherogenic chemokine and CXCR4 ligand that not only promotes lesion formation and vascular inflammation but also strongly affects hepatic lipogenesis in an SREBP-mediated manner, possibly linking atherosclerosis and hepatic steatosis.

scholarly journals The lncRNA Gm15622 stimulates SREBP-1c expression and hepatic lipid accumulation by sponging the miR-742-3p in mice

2020 ◽  
Vol 61 (7) ◽  
pp. 1052-1064 ◽  
Author(s):  
Minjuan Ma ◽  
Rui Duan ◽  
Lulu Shen ◽  
Mengting Liu ◽  
Yaya Ji ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Lipid Deposition ◽  
In Vivo Models ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Regulatory Circuit ◽  
Murine Liver

Excessive lipid deposition is a hallmark of NAFLD. Although much has been learned about the enzymes and metabolites involved in NAFLD, few studies have focused on the role of long noncoding RNAs (lncRNAs) in hepatic lipid accumulation. Here, using in vitro and in vivo models of NAFLD, we found that the lncRNA Gm15622 is highly expressed in the liver of obese mice fed a HFD and in murine liver (AML-12) cells treated with free fatty acids. Investigating the molecular mechanism in the liver-enriched expression of Gm15622 and its effects on lipid accumulation in hepatocytes and on NAFLD pathogenesis, we found that Gm15622 acts as a sponge for the microRNA miR-742-3p. This sponging activity increased the expression of the transcriptional regulator SREBP-1c and promoted lipid accumulation in the liver of the HFD mice and AML-12 cells. Moreover, further results indicated that metformin suppresses Gm15622 and alleviates NAFLD-associated lipid deposition in mice. In conclusion, we have identified an lncRNA Gm15622/miR-742-3p/SREBP-1c regulatory circuit associated with NAFLD in mice, a finding that significantly advances our insight into how lipid metabolism and accumulation are altered in this metabolic disorder. Our results also suggest that Gm15622 may be a potential therapeutic target for managing NAFLD.

scholarly journals Hepatic Lipid Accumulation Induced by a High-fat Diet Is Regulated by Nrf2 Through Multiple Pathways

2021 ◽  
Author(s):  
sheng Qiu ◽  
Zerong Liang ◽  
Qinan Wu ◽  
Miao Wang ◽  
Mengliu Yang ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Lipid Accumulation ◽  
High Fat Diet ◽  
Underlying Mechanism ◽  
Luciferase Assay ◽  
High Fat ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation

Abstract BackgroundNuclear factor erythroid 2-related factor 2 (Nrf2) is reportedly involved in hepatic lipid metabolism, but the results are contradictory and the underlying mechanism thus remains unclear. Herein we focused on elucidating the effects of Nrf2 on hepatic adipogenesis and on determining the possible underlying mechanism. We established a metabolic associated fatty liver disease (MAFLD) model in high fat diet (HFD) fed Nrf2 knockout (Nrf2 KO) mice; further, a cell model of lipid accumulation was established using mouse primary hepatocytes (MPHs) treated with free fatty acids (FAs). Using these models, we investigated the relationship between Nrf2 and autophagy and its role in the development of MAFLD.ResultsWe observed that Nrf2 expression levels were up-regulated in patients with MAFLD and diet-induced obese mice. Nrf2 deficiency led to hepatic lipid accumulation in vivo and in vitro, in addition to, promoting lipogenesis mainly by increasing SREBP-1 activity. Moreover, Nrf2 deficiency attenuated autophagic flux and inhibited the fusion of autophagosomes and lysosomes in vivo and in vitro. Weakened autophagy caused reduced lipolysis in the liver. Importantly, Chromatin immunoprecipitation-qPCR (ChIP-qPCR) and dual-luciferase assay results proved that Nrf2 bound to LAMP1 promoter and regulated its transcriptional activity. We accordingly report that Nrf2-LAMP1 interaction has an indispensable role in Nrf2-regulated hepatosteatosis. ConclusionsThese data collectively confirm that Nrf2 deficiency promotes hepatosteatosis by enhancing SREBP-1 activity and attenuating autophagy. To conclude, our data reveal a novel multi-pathway effect of Nrf2 on lipid metabolism in the liver, and we believe that multi-target intervention of Nrf2 signaling is a promising new strategy for the prevention and treatment of MAFLD.

scholarly journals Understanding the Role of Exercise in Nonalcoholic Fatty Liver Disease: ERS-Linked Molecular Pathways

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yong Zou ◽  
Zhengtang Qi
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
Nonalcoholic Fatty Liver Disease ◽  
Lipid Accumulation ◽  
Fatty Liver Disease ◽  
Molecular Pathways ◽  
Nonalcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation

Nonalcoholic fatty liver disease (NAFLD) is globally prevalent and characterized by abnormal lipid accumulation in the liver, frequently accompanied by insulin resistance (IR), enhanced hepatic inflammation, and apoptosis. Recent studies showed that endoplasmic reticulum stress (ERS) at the subcellular level underlies these featured pathologies in the development of NAFLD. As an effective treatment, exercise significantly reduces hepatic lipid accumulation and thus alleviates NAFLD. Confusingly, these benefits of exercise are associated with increased or decreased ERS in the liver. Further, the interaction between diet, medication, exercise types, and intensity in ERS regulation is more confusing, though most studies have confirmed the benefits of exercise. In this review, we focus on understanding the role of exercise-modulated ERS in NAFLD and ERS-linked molecular pathways. Moderate ERS is an essential signaling for hepatic lipid homeostasis. Higher ERS may lead to increased inflammation and apoptosis in the liver, while lower ERS may lead to the accumulation of misfolded proteins. Therefore, exercise acts like an igniter or extinguisher to keep ERS at an appropriate level by turning it up or down, which depends on diet, medications, exercise intensity, etc. Exercise not only enhances hepatic tolerance to ERS but also prevents the malignant development of steatosis due to excessive ERS.

scholarly journals Metformin Ameliorates Ethanol-Induced Liver Triglyceride Accumulation by LKB1/AMPK/ACC Pathway

2021 ◽  
Author(s):  
Fotian Xie ◽  
Dongmei Wang ◽  
Kwok Fai So ◽  
Jia Xiao ◽  
Yi Lv
Keyword(s):  
Lipid Accumulation ◽  
Therapeutic Potential ◽  
Lipid Lowering ◽  
Liver Triglyceride ◽  
Hepatic Lipid Accumulation ◽  
Triglyceride Accumulation ◽  
Lipid Formation

Abstract Background: Hepatic lipid accumulation is one of the main pathological features of alcoholic liver disease. Metformin is an AMPK activator that has been shown to have lipid lowering effects. The purpose of this study was to investigate whether metformin had a beneficial effect on lipid accumulation in the pathogenesis of ALD.Methods: AML12 cells and male C57BL/6 mice were used to establish ALD models in vitro and in vivo, respectively. The effects of metformin on hepatocyte lipid accumulation and ALD progression in mice were detected. The role of LKB1/AMPK/ACC axis in metformin against ethanol-induced lipid accumulation was evaluated by siRNA and AAV-shRNA interference.Results: Metformin reduced the ethanol-induced lipid accumulation in AML12 cells through activating AMPK/ACC and SREBP1c and inhibiting PPARα. In addition, compared with control mice, metformin treatment inhibited ethanol-induced liver adipose accumulation and the increase of ALT and AST in serum. Interference with LKB1 attenuated the effect of metformin on ethanol-induced lipid accumulation both in vitro and in vivo.Conclusion: Metformin protects against lipid formation in ALD by activating LKB1/AMPK/ACC axis. Thus, metformin has therapeutic potential for the prevention of ALD.

scholarly journals Ginseng seed oil ameliorates hepatic lipid accumulation in vitro and in vivo

2018 ◽  
Vol 42 (4) ◽  
pp. 419-428 ◽  
Author(s):  
Go Woon Kim ◽  
Hee Kyung Jo ◽  
Sung Hyun Chung
Keyword(s):  
Lipid Accumulation ◽  
Seed Oil ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation

scholarly journals Qushi Huayu Decoction Inhibits Hepatic Lipid Accumulation by Activating AMP-Activated Protein KinaseIn VivoandIn Vitro

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Qin Feng ◽  
Xiao-jun Gou ◽  
Sheng-xi Meng ◽  
Cheng Huang ◽  
Yu-quan Zhang ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Lipid Accumulation ◽  
Nuclear Protein ◽  
Nonalcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Element Binding Protein ◽  
L02 Cells

Qushi Huayu Decoction (QHD), a Chinese herbal formula, has been proven effective on alleviating nonalcoholic fatty liver disease (NAFLD) in human and rats. The present study was conducted to investigate whether QHD could inhibit hepatic lipid accumulation by activating AMP-activated protein kinase (AMPK)in vivoandin vitro. Nonalcoholic fatty liver (NAFL) model was duplicated with high-fat diet in rats and with free fatty acid (FFA) in L02 cells. Inin vivoexperimental condition, QHD significantly decreased the accumulation of fatty droplets in livers, lowered low-density lipoprotein cholesterol (LDL-c), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels in serum. Moreover, QHD supplementation reversed the HFD-induced decrease in the phosphorylation levels of AMPK and acetyl-CoA carboxylase (ACC) and decreased hepatic nuclear protein expression of sterol regulatory element-binding protein-1 (SREBP-1) and carbohydrate-responsive element-binding protein (ChREBP) in the liver. Inin vitro, QHD-containing serum decreased the cellular TG content and alleviated the accumulation of fatty droplets in L02 cells. QHD supplementation reversed the FFA-induced decrease in the phosphorylation levels of AMPK and ACC and decreased the hepatic nuclear protein expression of SREBP-1 and ChREBP. Overall results suggest that QHD has significant effect on inhibiting hepatic lipid accumulation via AMPK pathwayin vivoandin vitro.

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