Myostatin suppresses adipogenic differentiation and lipid accumulation by activating crosstalk between ERK1/2 and PKA signaling pathways in porcine subcutaneous preadipocytes

Author(s):  
Shifeng Pan ◽  
Lin Zhang ◽  
Zhuang Liu ◽  
Hua Xing

Abstract The current study was undertaken to determine the effect of myostatin (MSTN) on lipid accumulation in porcine subcutaneous preadipocytes (PSPAs) and to further explore the potential molecular mechanisms. PSPAs isolated from Meishan weaned piglets were added with various concentrations of MSTN recombinant protein during the entire period of adipogenic differentiation process. Results showed that MSTN treatment significantly reduced the lipid accumulation, intracellular triglyceride (TG) content, glucose consumption and glycerol phosphate dehydrogenase activity, while increased glycerol and free fatty acid release. Consistent with above results, the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway was obviously activated and thus key adipogenic transcription factors peroxisome proliferator-activated receptor-gamma (PPAR-γ), CCAAT/enhancer-binding protein-alpha (C/EBP-α) and their downstream engymes fatty acid synthase and acetyl-CoA carboxylase were all inhibited. However, chemical inhibition of ERK1/2 signaling pathway by PD98059 markedly reversed the decreased TG content by increasing PPAR-γ expression. In addition, MSTN activated the cyclic AMP/protein kinase A (cAMP/PKA) pathway and stimulated lipolysis by reducing the expression of antilipolytic gene perilipin, thus elevated key lipolytic enzymes adipose triglyceride lipase and hormone-sensitive lipase expression and enzyme activity. On the contrary, pretreatment with PKA inhibitor H89 significantly reversed TG accumulation by increasing PPAR-γ expression and thus inhibiting ERK1/2, perilipin and HSL phosphorylation, supporting the crosstalk between PKA and ERK1/2 pathways in both the anti-adipogenic and pro-lipolytic effects. In summary, our results suggested that MSTN suppressed adipogenesis and stimulated lipolysis, which was mainly mediated by activating crosstalk of ERK1/2 and PKA signaling pathways, and consequently decreased lipid accumulation in PSPAs, our findings may provide novel insights for further exploring MSTN as a potent inhibitor of porcine subcutaneous lipid accumulation.

2014 ◽  
Vol 53 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Amélie Gormand ◽  
Christine Berggreen ◽  
Lahouari Amar ◽  
Emma Henriksson ◽  
Ingrid Lund ◽  
...  

cAMP-response element-binding protein (CREB) is required for the induction of adipogenic transcription factors such as CCAAT/enhancer-binding proteins (C/EBPs). Interestingly, it is known from studies in other tissues that LKB1 and its substrates AMP-activated protein kinase (AMPK) and salt-inducible kinases (SIKs) negatively regulate gene expression by phosphorylating the CREB co-activator CRTC2 and class IIa histone deacetylases (HDACs), which results in their exclusion from the nucleus where they co-activate or inhibit their targets. In this study, we show that AMPK/SIK signalling is acutely attenuated during adipogenic differentiation of 3T3-L1 preadipocytes, which coincides with the dephosphorylation and nuclear translocation of CRTC2 and HDAC4. When subjected to differentiation, 3T3-L1 preadipocytes in which the expression of LKB1 was stably reduced using shRNA (Lkb1-shRNA), as well as Lkb1-knockout mouse embryonic fibroblasts (Lkb1−/− MEFs), differentiated more readily into adipocyte-like cells and accumulated more triglycerides compared with scrambled-shRNA-expressing 3T3-L1 cells or Wt MEFs. In addition, the phosphorylation of CRTC2 and HDAC4 was reduced, and the mRNA expression of adipogenic transcription factors Cebpa, peroxisome proliferator-activated receptor γ (Pparg) and adipocyte-specific proteins such as hormone-sensitive lipase (HSL), fatty acid synthase (FAS), aP2, GLUT4 and adiponectin was increased in the absence of LKB1. The mRNA and protein expression of Ddit3/CHOP10, a dominant-negative member of the C/EBP family, was reduced in Lkb1-shRNA-expressing cells, providing a potential mechanism for the up-regulation of Pparg and Cebpa expression. These results support the hypothesis that LKB1 signalling keeps preadipocytes in their non-differentiated form.


2019 ◽  
Vol 22 (6) ◽  
pp. 500-505
Author(s):  
Chiara Valtolina ◽  
Joris H Robben ◽  
Monique E van Wolferen ◽  
Hedwig S Kruitwagen ◽  
Ronald J Corbee ◽  
...  

Objectives The aim of this study was to evaluate if de novo hepatic lipid synthesis contributes to fatty acid overload in the liver of cats with feline hepatic lipidosis (FHL). Methods Lipogenic gene expression of peroxisome proliferator-activated receptor-alpha ( PPAR-α), peroxisome proliferator-activated receptor-gamma ( PPAR-γ), fatty acid synthase ( FASN) and sterol regulatory element-binding factor ( SREBF1) were evaluated using quantitative RT-PCR in liver tissue of six cats with FHL and compared with the liver tissue of eight healthy cats. Results In liver tissue, PPAR-α, PPAR-γ and FASN mRNA expression levels were not significantly different ( P >0.12, P >0.89 and P >0.5, respectively) in the FHL group compared with the control group. SREBF1 gene expression was downregulated around 10-fold in the FHL group vs the control group ( P = 0.039). Conclusions and relevance The downregulation of SREBF1 in the liver tissue of cats with FHL does not support the hypothesis that de novo lipogenesis in the liver is an important pathway of fatty acid accumulation in FHL.


2019 ◽  
Vol 74 (9-10) ◽  
pp. 265-273 ◽  
Author(s):  
Jung Im Lee ◽  
Jung Hwan Oh ◽  
Chang-Suk Kong ◽  
Youngwan Seo

Abstract This study was performed to isolate antiobesity components from the crude extract of Portulaca oleracea. The crude extract was partitioned into n-hexane, 85% aqueous methanol, n-butanol, and water fractions. Their effects on adipogenic differentiation were evaluated in 3T3-L1 cells. Among the solvent fractions from P. olearacea, the 85% aq. MeOH effectively reduced the levels of lipid accumulation. Further purification of 85% aq. MeOH led to the isolation of the known homoisoflavonoids 1–4, as the active substances. The administration of homoisoflavonoids to adipocyte cells decreased the lipid accumulation and glucose consumption and increased the release of glycerol into culture medium. In particular, homoisoflavonoid 3 effectively down-regulated the adipogenic transcription genes such as peroxisome proliferator activated receptor-γ (PPARγ) and CCAAT/enhancer-binding proteins (C/EBPα), and adipogenic target genes such as fatty acid binding protein 4 (FABP4), fatty acid transport protein 1 (FATP1), and acyl-CoA synthase 1 (ACS1).


2005 ◽  
Vol 288 (6) ◽  
pp. E1195-E1205 ◽  
Author(s):  
Susan E. Schadinger ◽  
Nancy L. R. Bucher ◽  
Barbara M. Schreiber ◽  
Stephen R. Farmer

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.


2018 ◽  
Vol 19 (9) ◽  
pp. 2555 ◽  
Author(s):  
Wei-Wei Guo ◽  
Xing Wang ◽  
Xiao-Qing Chen ◽  
Yin-Ying Ba ◽  
Nan Zhang ◽  
...  

Pinocembrin-7-O-β-d-glucoside (PCBG), pinocembrin (PCB), and 5-methoxy-pinocembrin-7-O-β-d-glucoside (MPG) are three flavonones isolated from Penthorum chinense Pursh (P. chinense). The effects of the three flavonones on hepatic steatosis and their molecular mechanisms in HepG2 cells were investigated in this study for the first time. A model of hepatic steatosis in HepG2 cells was induced by free fatty acid (FFA), and co-treated with the three flavonones as mentioned. Intracellular lipid droplets were detected by Oil Red O staining. PCB, PCBG, and MPG suppressed oxidative stress by decreasing malondialdehyde (MDA) levels and increasing superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. The levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were ameliorated. Moreover, these flavonones enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and the expression of silent mating type information regulation 2 homolog 1 (SIRT1) and peroxisome proliferator-activated receptor α (PPARα), and reduced the expression of sterol regulatory element binding protein-1c (SREBP1c) and the downstream targets fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), and stearoyl-CoA desaturase 1 (SCD1). Molecular docking was used to predict the interaction and combination patterns between the three flavonones and the enzymes above. The results revealed that the SIRT1/AMPK pathway is involved in the functions of the three flavonones, and the most effective flavonone against hepatic steatosis might be PCBG, followed by MPG and PCB. Therefore, the three flavonones from P. chinense were found to exert preventive effects against hepatic steatosis by regulating the SIRT1/AMPK pathway.


2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1608-1608
Author(s):  
Olugbenga Balogun ◽  
Ya Pei ◽  
Hye Won Kang

Abstract Objectives Excessive fat accumulation in the body, indicated as obesity causes development of other metabolic diseases, such as diabetes and cardiovascular diseases. Due to limitations of current strategies such as long-term engagement and high cost, new strategies to reduce the prevalence of obesity are needed. Garlic scape (Allium sativum L.) is the flower bud of the garlic plant that is removed to promote the growth of the bulb. Although most of garlic scape are trashed as a byproduct of garlic in the farm, it is still edible and includes various phytochemicals to improve human health. The purpose of this study was to investigate anti-obesity effect of garlic scape and its mechanism using 3T3-L1 cells. Methods Garlic scape extract (GSE) was prepared by solvent extraction using 80% methanol (v/v). 3T3-L1 cells, mouse embryonic fibroblast cells that mimic preadipocytes, were incubated with GSE during the differentiation. Total RNA and proteins from the cells were extracted. The expression of genes related to lipid metabolism such as peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer-binding protein (C\EBP) α and β, adipocyte protein (aP) 2, acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), sterol regulated element binding protein (SREBP) 1c, and carnitine palmitoyltransferase (CPT) 1α was determined using a quantitative PCR. The expression of proteins such as hormone sensitive lipase (HSL), ACC, and AMPK-activated protein kinase (AMPK) was measured using a western blot. Effect of GSE on lipid accumulation were visualized and quantified using Oil Red O staining. Results GSE decreased the expression of genes related to adipogenesis (PPARγ, C\EBPα, and C\EBPβ) and lipogenesis (ACC, FAS, and SREBP1c) whereas HSL and CPT1α genes and proteins related to lipolysis and fatty acid oxidation were not changed. Phosphorylation on both AMPK and ACC were increased. Adipocytes that were treated with GSE showed reduced lipid accumulation. Conclusions GSE inhibits fat accumulation in white adipocytes by decreasing adipogenesis and lipogenesis through possibly a AMPK pathway. Garlic scape may be a potential candidate to improve obese conditions. Funding Sources This work was supported by USDA.


Nutrients ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1857 ◽  
Author(s):  
Simona Terzo ◽  
Gaetano Caldara ◽  
Vincenzo Ferrantelli ◽  
Roberto Puleio ◽  
Giovanni Cassata ◽  
...  

Pistachios contain beneficial substances such as unsaturated fatty acids, phytosterols, and polyphenols. In the present study, we investigated if pistachio consumption is able to prevent or to revert hyperglycemia, dyslipidemia, hepatic steatosis, and adipose tissue morphological alterations caused by high fat diet (HFD) in the mouse. Moreover, the impact of pistachio intake on the mRNA expression of peroxisome proliferator-activated receptor γ (PPAR-γ), fatty acid transport proteins (FAT-P), fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD1), and sterol regulatory element-binding transcription factor-1c (SREBP-1c) in liver and adipose tissue was also analyzed. No change in body weight, food intake, and hyperglycemia was observed between mice consuming pistachios (HFD-P) and HFD mice. Pistachio intake was able to prevent but not to reverse HFD-induced hypertriglyceridemia. Cholesterol plasma levels, steatosis grading, body fat mass, and adipocyte size were significantly lower in HFD-P group compared to HFD in both prevention and reversal protocol. Pistachio-diet was able to prevent HFD-induced overexpression of PPAR-γ, FAS, and SCD1 in the liver and SREBP-1c, PPAR-γ, and FAT-P in adipose tissue. Similarly, HFD-P significantly ameliorated the expression levels of FAT-P and SCD1 in the liver and SREBP-1c, FAS, and SCD1 in adipose tissue of obese mice. The present study shows that pistachio consumption is able to prevent and to ameliorate obesity-related dysfunctions by positively modulating the expression of genes linked to lipid metabolism.


2008 ◽  
Vol 416 (2) ◽  
pp. 219-230 ◽  
Author(s):  
KyeongJin Kim ◽  
Kook Hwan Kim ◽  
Hyeong Hoe Kim ◽  
JaeHun Cheong

HBV (hepatitis B virus) is a primary cause of chronic liver disease, which frequently results in hepatitis, cirrhosis and ultimately HCC (hepatocellular carcinoma). Recently, we showed that HBx (HBV protein X) expression induces lipid accumulation in hepatic cells mediated by the induction of SREBP1 (sterol-regulatory-element-binding protein 1), a key regulator of lipogenic genes in the liver. However, the molecular mechanisms by which HBx increases SREBP1 expression and transactivation remain to be clearly elucidated. In the present study, we demonstrated that HBx interacts with LXRα (liver X receptor α) and enhances the binding of LXRα to LXRE (LXR-response element), thereby resulting in the up-regulation of SREBP1 and FAS (fatty acid synthase) in the presence or absence of the LXR agonist T0901317 in the hepatic cells and HBx-transgenic mice. Furthermore, HBx also augments the ability to recruit ASC2 (activating signal co-integrator 2), a transcriptional co-activator that controls liver lipid metabolic pathways, to the LXRE with LXRα. These studies place LXRα in a key position within the HBx-induced lipogenic pathways, and suggest a molecular mechanism through which HBV infection can stimulate the SREBP1-mediated control of hepatic lipid accumulation.


Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3598
Author(s):  
Mei-Chih Tsai ◽  
Shih-Chien Huang ◽  
Wei-Tang Chang ◽  
Shiuan-Chih Chen ◽  
Chin-Lin Hsu

Obesity is defined as a condition of excessive fat tissue accumulation. It was the major factor most closely associated with lifestyle-related diseases. In the present study, we investigated the effect of astaxanthin on the inhibition of lipid accumulation in 3T3-L1 adipocytes. 3T3-L1 adipocytes were treated with 0–25 µg/mL of astaxanthin for 0–48 h. The result indicated that astaxanthin significantly decreased the oil Red O stained material (OROSM), intracellular triglyceride accumulation, and glycerol 3-phosphate dehydrogenase (GPDH) activity in 3T3-L1 adipocytes (p < 0.05). At the molecular level, astaxanthin significantly down-regulated the mRNA expression of peroxisome proliferator-activated receptor-γ (PPARγ) in 3T3-L1 adipocytes (p < 0.05). Moreover, target genes of PPARγ on the inhibition of lipogenesis, such as Acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), fatty acid binding protein (aP2), cluster of differentiation 36 (CD36), and lipoprotein lipase (LPL) in 3T3-L1 adipocytes were significantly down-regulated at a time-dependent manner (p < 0.05). These results suggested that astaxanthin efficiently suppressed lipid accumulation in 3T3-L1 adipocytes and its action is associated with the down-regulation of lipogenesis-related genes and the triglyceride accumulation in 3T3-L1 adipocytes. Therefore, astaxanthin can be developed as a potential nutraceutical ingredient for the prevention of obesity in a niche market.


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