scholarly journals L-theanine Prevents Progression of Nonalcoholichepatic Steatosis by Regulating Hepatocyte Lipid Metabolic Pathways via the CaMKKβ-AMPK Signaling Pathway

2021 ◽  
Author(s):  
Juanjuan Liang ◽  
Lili Gu ◽  
Xianli Liu ◽  
Xintong Yan ◽  
Xiaowen Bi ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Protein Kinase ◽  
Signaling Pathway ◽  
Hepatic Steatosis ◽  
Metabolic Pathways ◽  
Alcoholic Fatty Liver ◽  
Ampk Signaling ◽  
Nonalcoholic Hepatic Steatosis

Abstract Background: L-theanine, a non-protein amino acid found principally in the green tea, has been previously shown to possess potent anti-obesity property and hepatoprotective effect. Herein, we investigated the effects of L-theanine on alleviating nonalcoholic hepatic steatosis in vitro and in vivo, and explored the underlying molecular mechanism. Methods: In vitro, HepG2 and AML12 cells were treated with 500 μM oleic acid (OA) or treated with OA accompanied by L-theanine. In vivo, C57BL/6J mice were fed with normal control diet (NCD), high‐fat diet (HFD), or HFD along with L-theanine for 16 weeks. The levels of TG, accumulation of lipid droplets and the expression of genes related to hepatocyte lipid metabolic pathways were detected in vitro and in vivo.Results: Our data indicated that, in vivo, L-theanine significantly reduced body weight, hepatic steatosis, serum levels of alanine transaminase (ALT), aspartate transaminase (AST), TG and LDL cholesterol (LDL-C) in HFD-induced Non-alcoholic fatty liver disease (NAFLD) mice. In vitro, L-theanine also significantly alleviated OA induced hepatocytes steatosis. Mechanic studies showed that L-theanine significantly inhibited the nucleus translocation of sterol regulatory element binding protein 1c (SREBP-1c) through AMPK-mTOR signaling pathway, thereby contributing to the reduction of fatty acid synthesis. We also identified that L-theanine enhanced fatty acid β-oxidation by increasing the expression of peroxisome proliferator–activated receptor α (PPARα) and carnitine palmitoyltransferase-1 A (CPT1A) through AMP-activated protein kinase (AMPK). Furthermore, our study indicated that L-theanine can active AMPK via its upstream kinase Calmodulin-dependent protein kinase kinase-β (CaMKKβ). Conclusions: Taken together, our findings suggest that L-theanine alleviates nonalcoholic hepatic steatosis by regulating hepatocyte lipid metabolic pathways via the CaMKKβ-AMPK signaling pathway.

scholarly journals Glucagon regulates ACC activity in adipocytes through the CAMKKβ/AMPK pathway

2012 ◽  
Vol 302 (12) ◽  
pp. E1560-E1568 ◽  
Author(s):  
I-Chen Peng ◽  
Zhen Chen ◽  
Wei Sun ◽  
Ying-Shiuan Li ◽  
Traci LaNai Marin ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Lipid Metabolism ◽  
Protein Kinase ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Dependent Protein Kinase ◽  
Ampk Signaling ◽  
Dependent Protein

Glucagon is important for regulating lipid metabolism in part through its inhibition of fatty acid synthesis in adipocytes. Acetyl-CoA carboxylase 1 (ACC1) is the rate-limiting enzyme for fatty acid synthesis. Glucagon has been proposed to activate cAMP-dependent protein kinase A (PKA), which phosphorylates ACC1 to attenuate the lipogenic activity of ACC1. Because AMP-activated protein kinase (AMPK) also inhibits fatty acid synthesis by phosphorylation of ACC1, we examined the involvement of AMPK and its upstream kinase in the glucagon-elicited signaling in adipocytes in vitro and in vivo. LC-MS-MS analysis suggested that ACC1 was phosphorylated only at Ser79, an AMPK-specific site, in glucagon-treated adipocytes. Pharmacological inhibitors and siRNA knockdown of AMPK or PKA in adipocytes demonstrate that glucagon regulates ACC1 and ACC2 activity through AMPK but not PKA. By using Ca2+/calmodulin-dependent protein kinase kinase-β knockout (CaMKKβ−/−) mice and cultured adipocytes, we further show that glucagon activates the CaMKKβ/AMPK/ACC cascade. Additionally, fasting increases the phosphorylation of AMPK and ACC in CaMKKβ+/+ but not CaMKKβ−/− mice. These results indicate that CaMKKβ/AMPK signaling is an important molecular component in regulating lipid metabolism in adipocytes responding to glucagon and could be a therapeutic target for the dysregulation of energy storage.

Fucoidans from Cucumaria frondosa ameliorates renal interstitial fibrosis via inhibition of PI3K/Akt/NF-κB signaling pathway

2022 ◽  
Author(s):  
Zhuo-yue Song ◽  
Mengru Zhu ◽  
Jun Wu ◽  
Tian Yu ◽  
Yao Chen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Interstitial Fibrosis ◽  
Protein Kinase B ◽  
Nuclear Factor Κb ◽  
Nuclear Factor ◽  
Renal Interstitial Fibrosis ◽  
Cucumaria Frondosa

The effects of Cucumaria frondosa polysaccharides (CFP) on renal interstitial fibrosis via regulating phosphatidylinositol-3-hydroxykinase/protein kinase-B/Nuclear factor-κB (PI3K/AKT/NF-κB) signaling pathway were investigated in vivo and in vitro in this research. A...

scholarly journals Betatrophin knockdown induces beiging and mitochondria biogenesis of white adipocytes

2020 ◽  
Vol 245 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Zhe-Zhen Liao ◽  
Xiao-Yan Qi ◽  
Ya-Di Wang ◽  
Jiao-Yang Li ◽  
Qian-Qian Gu ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Ampk Signaling ◽  
White Adipocytes ◽  
Beige Adipocytes ◽  
Beige Fat ◽  
Mitochondria Biogenesis ◽  
Paracrine Actions ◽  
White Fat

Remodeling of energy-storing white fat into energy-consuming beige fat has led to a promising new approach to alleviate adiposity. Several studies have shown adipokines can induce white adipose tissue (WAT) beiging through autocrine or paracrine actions. Betatrophin, a novel adipokine, has been linked to energy expenditure and lipolysis but not clearly clarified. Here, we using high-fat diet-induced obesity to determine how betatrophin modulate beiging and adiposity. We found that betatrophin-knockdown mice displayed less white fat mass and decreased plasma TG and NEFA levels. Consistently, inhibition of betatrophin leads to the phenotype change of adipocytes characterized by increased mitochondria contents, beige adipocytes and mitochondria biogenesis-specific markers both in vivo and in vitro. Of note, blocking AMP-activated protein kinase (AMPK) signaling pathway is able to abolish enhanced beige-like characteristics in betatrophin-knockdown adipocytes. Collectively, downregulation of betatrophin induces beiging in white adipocytes through activation of AMPK signaling pathway. These processes suggest betatrophin as a latent therapeutic target for obesity.

scholarly journals Activation of TAF9 via Danshensu-Induced Upregulation of HDAC1 Expression Alleviates Non-alcoholic Fatty Liver Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Ruiwen Wang ◽  
Zhecheng Wang ◽  
Ruimin Sun ◽  
Rong Fu ◽  
Yu Sun ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Liver Disease ◽  
Fatty Liver ◽  
Protective Effect ◽  
Fatty Liver Disease ◽  
Cell Model ◽  
Signaling Mechanism ◽  
Alcoholic Fatty Liver

Fatty acid β-oxidation is an essential pathogenic mechanism in nonalcoholic fatty liver disease (NAFLD), and TATA-box binding protein associated factor 9 (TAF9) has been reported to be involved in the regulation of fatty acid β-oxidation. However, the function of TAF9 in NAFLD, as well as the mechanism by which TAF9 is regulated, remains unclear. In this study, we aimed to investigate the signaling mechanism underlying the involvement of TAF9 in NAFLD and the protective effect of the natural phenolic compound Danshensu (DSS) against NAFLD via the HDAC1/TAF9 pathway. An in vivo model of high-fat diet (HFD)-induced NAFLD and a palmitic acid (PA)-treated AML-12 cell model were developed. Pharmacological treatment with DSS significantly increased fatty acid β-oxidation and reduced lipid droplet (LD) accumulation in NAFLD. TAF9 overexpression had the same effects on these processes both in vivo and in vitro. Interestingly, the protective effect of DSS was markedly blocked by TAF9 knockdown. Mechanistically, TAF9 was shown to be deacetylated by HDAC1, which regulates the capacity of TAF9 to mediate fatty acid β-oxidation and LD accumulation during NAFLD. In conclusion, TAF9 is a key regulator in the treatment of NAFLD that acts by increasing fatty acid β-oxidation and reducing LD accumulation, and DSS confers protection against NAFLD through the HDAC1/TAF9 pathway.

Abstract 344: FNDC5, a PGC1-a-Dependent Myokine, Increases Glucose Utilization and Fatty-Acid Oxidation by AMPK Signaling Pathway

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Ling Tao ◽  
Yi Liu ◽  
Chao Xin ◽  
Weidong Huang ◽  
Lijian Zhang ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Glucose Uptake ◽  
Fatty Acid Oxidation ◽  
Glucose Utilization ◽  
C2c12 Cells ◽  
Time Dependent ◽  
Acid Oxidation ◽  
Ampk Signaling

FNDC5 is a hormone secreted by myocytes that could reduce obesity and insulin resistance, However, the exact effect of FNDC5 on glucose and lipid metabolism remain poorly identified; More importantly, the signaling pathways that mediate the metabolic effects of FNDC5 is completely unknown. Here we showed that FNDC5 stimulates β-oxidation and glucose uptake in C2C12 cells in a dose- and time-dependent fashion in vitro (n=8, all P<0.01). In vivo study revealed that FNDC5 also enhanced glucose tolerance in diabetic mice and increased the glucose uptake evidenced by increased [18F] FDG accumulation in hearts by PET scan (n=6, all P<0.05). FNDC5 decreased the expression of gluconeogenesis related molecules (PEPCK and G6Pase) and increased the phosphorylation of ACC, a key modulator of fatty-acid oxidation, both in hepatocytes and C2C12 cells (n=3, all P<0.05). In parallel with its stimulation of β-oxidation and glucose uptake, FNDC5 increased the phosphorylation of AMPK both in hepatocytes and C2C12 cells in a dose- and time-dependent fashion in vitro and in vivo. More importantly, the β-oxidation and glucose uptake, the expression of PEPCK and G6Pase and the phosphorylation of ACC induced by FNDC5 were attenuated by AMPK inhibitor in hepatocytes and C2C12 cells (P<0.05). Most importantly, the FNDC5 induced glucose uptake and phosphorylation of ACC were attenuated in AMPK-DN mice (n=6, all P<0.05). The glucose-lowering effect of FNDC5 in diabetic mice was also attenuated by AMPK inhibitor. Our data presents the direct evidence that FNDC5 stimulates glucose utilization and fatty-acid oxidation by AMPK signaling pathway, suggesting that FNDC5 be a novel pharmacological approach for type 2 diabetes.

Adiponectin promotes VEGF-C-dependent lymphangiogenesis by inhibiting miR-27b through a CaMKII/AMPK/p38 signaling pathway in human chondrosarcoma cells

2016 ◽  
Vol 130 (17) ◽  
pp. 1523-1533 ◽  
Author(s):  
Chun-Yin Huang ◽  
An-Chen Chang ◽  
Hsien-Te Chen ◽  
Shih-Wei Wang ◽  
Yuan-Shun Lo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Tube Formation ◽  
Human Chondrosarcoma ◽  
Dependent Protein ◽  
And Migration ◽  
Factor C ◽  
Amp Activated Protein Kinase

Chondrosarcoma is the second most frequently occurring type of bone malignancy characterized by distant metastatic propensity. Vascular endothelial growth factor-C (VEGF-C) is the major lymphangiogenic factor, and makes crucial contributions to tumour lymphangiogenesis and lymphatic metastasis. Adiponectin is a protein hormone secreted predominantly by differentiated adipocytes. In recent years, adiponectin has also been indicated as facilitating tumorigenesis, angiogenesis and metastasis. However, the effect of adiponectin on VEGF-C regulation and lymphangiogenesis in chondrosarcoma has remained largely a mystery. In the present study, we have shown a clinical correlation between adiponectin and VEGF-C, as well as tumour stage, in human chondrosarcoma tissues. We further demonstrated that adiponectin promoted VEGF-C expression and secretion in human chondrosarcoma cells. The conditioned medium from adiponectin-treated cells significantly induced tube formation and migration of human lymphatic endothelial cells. In addition, adiponectin knock down inhibited lymphangiogenesis in vitro and in vivo. We also found that adiponectin-induced VEGF-C is mediated by the calmodulin-dependent protein kinase II (CaMKII), AMP-activated protein kinase (AMPK) and p38 signaling pathway. Furthermore, the expression of miR-27b was negatively regulated by adiponectin via the CaMKII, AMPK and p38 cascade. The present study is the first to describe the mechanism of adiponectin-promoted lymphangiogenesis by up-regulating VEGF-C expression in chondrosarcomas. Thus, adiponectin could serve as a therapeutic target in chondrosarcoma metastasis and lymphangiogenesis.

scholarly journals Naringin protects against non-alcoholic fatty liver disease by promoting autophagic flux and lipophagy

2021 ◽  
Author(s):  
Lingling Guan ◽  
Lan Guo ◽  
Heng Zhang ◽  
Hao Liu ◽  
Yuan Qiao ◽  
...  
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
Hepatic Steatosis ◽  
Fatty Liver Disease ◽  
Autophagic Flux ◽  
Mechanism Study ◽  
Alcoholic Fatty Liver ◽  
Alcoholic Fatty Liver Disease

Abstract Background and Purpose: The autophagic degradation of lipid droplets (LDs), termed lipophagy, is the main mechanism contributing to lipid consumption in hepatocytes. The identification of effective and safe natural compounds that target lipophagy to eliminate excess lipids may be a potential therapeutic strategy for non-alcoholic fatty liver disease (NAFLD). Here, we investigated the effects of naringin on NAFLD and the underlying mechanism. Experimental Approach: The role of naringin was investigated in mice fed a high-fat diet (HFD) to induce NAFLD, as well as in AML12 cells and primary hepatocytes stimulated by palmitate (PA). Transcription factor EB (TFEB)-knockdown AML12 cells and hepatocyte-specific TFEB-knockout mice were also used for the mechanism study. In vivo and in vitro studies were conducted using transmission electron microscopy, immunofluorescence techniques and western blot analysis. Key Results: We found that naringin treatment effectively relieved HFD-induced hepatic steatosis in mice and inhibited palmitate (PA)-induced lipid accumulation in hepatocytes. The increased p62 and LC3-II levels observed with excess lipid-support autophagosome accumulation and impaired autophagic flux. Treatment with naringin restored TFEB-mediated lysosomal biogenesis, thereby promoting the fusion of autophagosomes and lysosomes, restoring impaired autophagic flux and further inducing lipophagy. However, the knockdown of TFEB in hepatocytes or the hepatocyte-specific knockout of TFEB in mice abrogated naringin-induced lipophagy, which eliminated the therapeutic effect of naringin on hepatic steatosis. Conclusion and Implications: These results demonstrate that TFEB-mediated lysosomal biogenesis and subsequent lipophagy play essential roles in the ability of naringin to mitigate hepatic steatosis and suggest that naringin is a promising drug for treating or relieving NAFLD.

scholarly journals Docosahexaenoic Acid Lessens Hepatic Lipid Accumulation and Inflammation via the AMP-Activated Protein Kinase and Endoplasmic Reticulum Stress Signaling Pathway in Grass Carp (Ctenopharyngodon Idella)

2021 ◽  
Author(s):  
Xiaocheng Huang ◽  
Jian Sun ◽  
Chenchen Bian ◽  
Shanghong Ji ◽  
Hong ji
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Kinase ◽  
Hepatic Steatosis ◽  
Grass Carp ◽  
Lipid Accumulation ◽  
Ctenopharyngodon Idella ◽  
Hepatic Inflammation ◽  
Amp Activated Protein Kinase

Abstract Background: The liver is the primary organ for frontline immune defense and lipid metabolism. Excessive lipid accumulation in the liver severely affects its metabolic homeostasis and causes metabolic diseases. Docosahexaenoic acid (DHA) is known for its beneficial effects on lipid metabolism and anti-inflammation, but its molecular mechanism remains unknown, especially in fish. In this study, we evaluated the protective effects of DHA on hepatic steatosis of grass carp (Ctenopharyngodon idella) in vivo and in vitro and mainly focused on lipogenesis and inflammation. Grass carp were fed with purified diets supplemented with 0%, 0.5% and 1% DHA for 8 weeks in vivo. Hepatocytes were treated with palmitic acid (PA) (200 μM) with or without DHA (50 or 100 μM) for 24 h in vitro. In addition, Compound C (CC, the inhibitor of AMP-activated protein kinase) was used to examine the mechanism of DHA on hepatic steatosis in vitro.Results: In this study, 1% DHA significantly decreased the liver triglyceride (TG), malondialdehyde (MDA), serum tumor necrosis factor α (TNFα) and nuclear factor kappa B (NFκB) contents. DHA (100 μM) effectively attenuated PA-induced lipid accumulation (P<0.05). Furthermore, DHA significantly inhibited endoplasmic reticulum (ER) stress and stimulated the expression of AMP-activated protein kinase (AMPK) and its downstream factors related to hepatic inflammation and lipogenesis in vivo and in vitro. However, the effects of DHA could be abrogated by CC in vitro.Conclusions: DHA exerted a protective effect on hepatic steatosis by inhibiting ER stress, improving antioxidant ability, relieving hepatic inflammation and inhibiting hepatic lipogenesis in an AMPK-dependent manner. Our findings give a theoretical foundation for further elucidation of the beneficial role of DHA in vertebrates.

scholarly journals TMEM88 Modulates Lipid Synthesis and Metabolism Cytokine by Regulating Wnt/β-Catenin Signaling Pathway in Non-Alcoholic Fatty Liver Disease

2022 ◽  
Vol 12 ◽  
Author(s):  
Huan Zhou ◽  
Xingyu Zhu ◽  
Yan Yao ◽  
Yue Su ◽  
Jing Xie ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Western Blotting ◽  
Lipid Synthesis ◽  
Alcoholic Fatty Liver ◽  
Downstream Target ◽  
New Ideas ◽  
Mice Liver ◽  
Alcoholic Fatty Liver Disease

Objective: To clarify the molecular mechanism of TMEM88 regulating lipid synthesis and metabolism cytokine in NAFLD.Methods:In vivo, NAFLD model mice were fed by a Methionine and Choline-Deficient (MCD) diet. H&amp;E staining and immunohistochemistry experiments were used to analyze the mice liver tissue. RT-qPCR and Western blotting were used to detect the lipid synthesis and metabolism cytokine. In vitro, pEGFP-C1-TMEM88 and TMEM88 siRNA were transfected respectively in free fat acid (FFA) induced AML-12 cells, and the expression level of SREBP-1c, PPAR-α, FASN, and ACOX-1 were evaluated by RT-qPCR and Western blotting.Results: The study found that the secretion of PPAR-α and its downstream target ACOX-1 were upregulated, and the secretion of SREBP-1c and its downstream target FASN were downregulated after transfecting with pEGFP-C1-TMEM88. But when TMEM88 was inhibited, the experimental results were opposite to the aforementioned conclusions. The data suggested that it may be related to the occurrence, development, and end of NAFLD. Additionally, the study proved that TMEM88 can inhibit Wnt/β-catenin signaling pathway. Meanwhile, TMEM88 can accelerate the apoptotic rate of FFA-induced AML-12 cells.Conclusion: Overall, the study proved that TMEM88 takes part in regulating the secretion of lipid synthesis and metabolism cytokine through the Wnt/β-catenin signaling pathway in AML-12 cells. Therefore, TMEM88 may be involved in the progress of NAFLD. Further research will bring new ideas for the study of NAFLD.

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