Regulation Of Lipogenesis Research Articles

E2F1 mediates sustained lipogenesis and contributes to hepatic steatosis.

E2F transcription factors are known regulators of the cell cycle, proliferation, apoptosis, and differentiation. Here, we reveal that E2F1 plays an essential role in liver physiopathology through the regulation of glycolysis and lipogenesis. We demonstrate that E2F1 deficiency leads to a decrease in glycolysis and de novo synthesis of fatty acids in hepatocytes. We further demonstrate that E2F1 directly binds to the promoters of key lipogenic genes, including Fasn, but does not bind directly to genes encoding glycolysis pathway components, suggesting an indirect effect. In murine models, E2F1 expression and activity increased in response to feeding and upon insulin stimulation through canonical activation of the CDK4/pRB pathway. Moreover, E2F1 expression was increased in liver biopsies from obese, glucose-intolerant humans compared with biopsies from lean subjects. Finally, E2f1 deletion completely abrogated hepatic steatosis in different murine models of nonalcoholic fatty liver disease (NAFLD). In conclusion, our data demonstrate that E2F1 regulates lipid synthesis and glycolysis and thus contributes to the development of liver pathology.

Caffeine reduces hepatic lipid accumulation through regulation of lipogenesis and ER stress in zebrafish larvae.

BackgroundCaffeine, the main component of coffee, has showed its protective effect on non-alcoholic fatty liver disease (NAFLD) in many studies. However, the hepatoprotection of caffeine and its mechanisms in zebrafish were unexplored. Thus, this study’s intentions are to establish a NAFLD model of zebrafish larvae and to examine the role of caffeine on fatty liver with the model.ResultsGrowth and the incidence of fatty liver of zebrafish larvae increased with the increased amount of feeding in a dose-dependent manner. The degree of hepatic steatosis of larvae also gradually aggravated with the increased quantity and duration of feeding. Triglyceride contents of zebrafish fed for 20 days significantly increased in model group (180 mg/d) compared with control group (30 mg/d) (P < 0.001). Significant decreases in body weight and hepatic steatosis rate were observed in 2.5, 5, 8 % caffeine treatment group compared with model group (P < 0.05). Hepatic lipid accumulation was also significantly reduced in caffeine treatment larvae. Moreover, caffeine treatment was associated with upregulation of lipid β-oxidation gene ACO and downregulation of lipogenesis-associated genes (SREBP1, ACC1, CD36 and UCP2), ER stress-associated genes (PERK, IRE1, ATF6 and BIP), the inflammatory cytokine genes (IL-1beta and TNF-alpha) and autophagy associated genes (ATG12 and Beclin-1). Protein expression of CHOP, BIP and IL-1beta remarkably reduced in caffeine treatment group compared with model group.ConclusionsWe induced hepatoteatosis in zebrafish by overfeeding regimen and demonstrated caffeine have a role in suppression of hepatosteatosis by downregulation of genes associated with lipogenesis, ER stress, inflammatory response and enhancement of lipid oxidation, indicating zebrafish model may be used to identify putative pharmacological targets and to test novel drugs for human NAFLD treatment.

Wnt/β-catenin signaling participates in the regulation of lipogenesis in the liver of juvenile turbot (Scophthalmus maximus L.).

In this study, the mechanism that Wnt/β-catenin signaling inhibits lipogenesis was investigated in the liver of juvenile turbot (Scophthalmus maximus L.) by LiCl or XAV939 treatment. Wnt/β-catenin signaling was activated by LiCl treatment or inhibited by XAV939 treatment through regulating the expression of glycogen synthase kinase-3β (GSK-3β) and Wnt10b. In addition, the expression of lipoprotein lipase (LPL), fatty acid synthetase (FAS), peroxisome proliferator-activated receptor γ (PPARγ), and CCAAT/enhancer binding protein α (C/EBPα) was inhibited by LiCl treatment, but induced by XAV939 treatment. In the plasma of juvenile turbot, the level of nonesterified fatty acid (NEFA), glycerol, triglyceride (TG), total cholesterol (TC), and low density lipoprotein cholesterol (LDL-C) was decreased by LiCl treatment, which was related to the decrease of the activity of LPL and FAS. Thus the inhibitory effect of Wnt/β-catenin signaling on lipogenesis was associated with the expression of key enzymes and transcriptional factors. Wnt/β-catenin signaling may participate in inhibiting lipogenesis by inhibiting the expression of PPARγ and C/EBPα in the liver of juvenile turbot.

Transcriptional regulation of hepatic lipogenesis.

Fatty acid and fat synthesis in the liver is a highly regulated metabolic pathway that is important for very low-density lipoprotein (VLDL) production and thus energy distribution to other tissues. Having common features at their promoter regions, lipogenic genes are coordinately regulated at the transcriptional level. Transcription factors, such as upstream stimulatory factors (USFs), sterol regulatory element-binding protein 1C (SREBP1C), liver X receptors (LXRs) and carbohydrate-responsive element-binding protein (ChREBP) have crucial roles in this process. Recently, insights have been gained into the signalling pathways that regulate these transcription factors. After feeding, high blood glucose and insulin levels activate lipogenic genes through several pathways, including the DNA-dependent protein kinase (DNA-PK), atypical protein kinase C (aPKC) and AKT-mTOR pathways. These pathways control the post-translational modifications of transcription factors and co-regulators, such as phosphorylation, acetylation or ubiquitylation, that affect their function, stability and/or localization. Dysregulation of lipogenesis can contribute to hepatosteatosis, which is associated with obesity and insulin resistance.

SH2 domain-containing inositol 5-phosphatase (SHIP2) inhibition ameliorates high glucose-induced de-novo lipogenesis and VLDL production through regulating AMPK/mTOR/SREBP1 pathway and ROS production in HepG2 cells

Hepatic de-novo lipogenesis and production of triglyceride rich very low density lipoprotein (VLDL) is increased in the state of insulin resistance, however, the role of a negative regulator of the insulin signaling pathway, the SH2 domain-containing inositol 5-phosphatase (SHIP2) in this process, remains unknown. In the present study, we studied the molecular mechanisms linking SHIP2 expression to metabolic dyslipidemia using overexpression or suppression of SHIP2 gene in HepG2 cells exposed to high glucose (33mM). The results showed that high glucose induced SHIP2 mRNA and protein levels in HepG2 cells. Overexpression of the dominant negative mutant SHIP2 (SHIP2-DN) ameliorated high glucose-induced de-novo lipogenesis and secretion of apoB containing lipoprotein in HepG2 cells, as demonstrated by a reduction in both secreted apoB and MTP expression, and decreased triglyceride levels and the expression of lipogenic genes such as SREBP1c, FAS and ACC. Overexpression of the SHIP2-DN decreased high glucose-induced apoB containing lipoproteins secretion via reduction in ROS generation, JNK phosphorylation and Akt activation. Furthermore, using the specific inhibitor and activator, it was found that the AMPK/mTOR/SREBP1 is the signaling pathway that mediates the effects of SHIP2 modulation on hepatic de-novo lipogenesis. Taken together, these findings suggest that SHIP2 is an important regulator of hepatic lipogenesis and lipoprotein secretion in insulin resistance state.

Tribbles-1: a novel regulator of hepatic lipid metabolism in humans.

The protein tribbles-1, encoded by the gene TRIB1, is increasingly recognized as a major regulator of multiple cellular and physiological processes in humans. Recent human genetic studies, as well as molecular biological approaches, have implicated this intriguing protein in the aetiology of multiple human diseases, including myeloid leukaemia, Crohn's disease, non-alcoholic fatty liver disease (NAFLD), dyslipidaemia and coronary artery disease (CAD). Genome-wide association studies (GWAS) have repeatedly identified variants at the genomic TRIB1 locus as being significantly associated with multiple plasma lipid traits and cardiovascular disease (CVD) in humans. The involvement of TRIB1 in hepatic lipid metabolism has been validated through viral-mediated hepatic overexpression of the gene in mice; increasing levels of TRIB1 decreased plasma lipids in a dose-dependent manner. Additional studies have implicated TRIB1 in the regulation of hepatic lipogenesis and NAFLD. The exact mechanisms of TRIB1 regulation of both plasma lipids and hepatic lipogenesis remain undetermined, although multiple signalling pathways and transcription factors have been implicated in tribbles-1 function. Recent reports have been aimed at developing TRIB1-based lipid therapeutics. In summary, tribbles-1 is an important modulator of human energy metabolism and metabolic syndromes and worthy of future studies aimed at investigating its potential as a therapeutic target.

Extracts and lignans of Schisandra chinensis fruit alter lipid and glucose metabolism in vivo and in vitro

The antihyperlipidaemic effect and potential mechanisms of Schisandra chinensis fruit extract were investigated in hamsters fed with a high-fat diet. Treating with SF extract significantly decreased the serum levels of total cholesterol, triacylglycerol and low-density lipoprotein cholesterol, alleviated insulin resistance, attenuated inflammation and declined liver lipid accumulation. The expression and activities of key lipid-metabolic regulators were altered to the lipid-lowering side. Screening of different fractions of SF extract for lipid-lowering activities revealed that the lignan-rich fraction was the most effective. Eight abundant lignans were isolated from the major active fraction of SF extract, in which schisandrols A, B and schisandrins B, C showed significant lipid-lowering effects in HepG2 cells, and schisandrin C was potent in decreasing the blood lipids in Triton WR-1339 induced hyperlipidaemic mice. Overall, these results indicated that the extract and lignans in SF were effective regulators of lipogenesis and could be useful for treating hyperlipidaemia.

Expression of Adenosine Monophosphate-Activated Protein Kinase Subunit Related to the Rate of Intramuscular Lipogenesis in Fast and Slow-Growing Chicken Strains

The objective of this study was to compare the expression of adenosine monophosphate-activated protein kinase ( AMPK) and its relation to rates of lipogenesis in the muscle of fast (Arbor Acres, AA chickens)-and slow (Bei-Jing-You, BJY chickens)-growing chicken strains. Twelve birds for each strain were selected and slaughtered at 8 weeks of age for AA chickens and week 8, week 16 for BJY chickens. The amount of intramuscular fat (IMF) content, expression of AMPK subunits and key regulators of lipogenesis in the thigh and breast muscle tissue were determined. Results showed that the content of IMF and expression of peroxisome proliferator activated receptors γ, FA translocase CD36 and fatty acid synthase in the thigh and breast muscle of week 16 BJY were significantly higher than those for week 8 AA and week 8 BJY chickens ( P &lt; 0.05). Compared with AA chickens at 8 weeks, at 16 weeks, the BJY showed a significantly lower expression of AMPK subunits (except subunits α1 and γ3 in thigh and β1 and γ2 in breast) in the muscle ( P &lt; 0.05). To examine the role of AMPK on adipogenesis, the muscle-derived stromal-vascular cells were cultured in adipogenic medium and treated with AICAR and Compound C. The administration of compound C significantly induced expression of CCAAT/enhancer-binding protein factors β, sterol regulatory element-binding protein 1 and peroxisome proliferator activated receptors γ ( P &lt; 0.05), and AICAR-induced AMPK activation inhibited adipogenic gene expression. In conclusion, there was a significantly higher IMF content and lipogenic gene expression in week 16 BJY than week 8 AA. AMPK expression negatively related to intramuscular lipid in chickens.

Abstract 1142: COP1 functions as a sensor of cellular lipids and regulator of lipogenesis in human cancer cells

Abstract Background Constitutive photomorphogenesis protein 1 (COP1; also known as Rfwd2), an evolutionally conserved E3 ubiquitin ligase, has been defined to mediate the degradation of several important proteins, such as p53, c-Jun, ETS, FOXO1 and ACC1, being involved in tumorigenesis. In response to DNA damage, COP1 is autodegraded in the context of ATM, which is triggered by 14-3-3σ. However, the biological function and expression regulation of COP1 remain to be fully understood. This study reports a novel function of COP1 in lipid metabolism. Methods We targeted COP1 expression in cancer cells MCF-7 and HepG2 with COP1 shRNA lentivirus and COP1 overexpression lentivirus, respectively. We investigated the lipid synthesis, glucose oxidation and conversion into lipids in these cells using radiolabeled acetate and glucose and lipid complex analysis. Quantitative real-time PCR and Western blot were used to examine gene expression. Acetyl CoA carboxylase-1 (ACC1) siRNA and TOFA, an inhibitor of ACC1, were used to modulate the intracellular lipid synthesis. Results Lipid depletion induced by acetyl CoA carboxylase-1 (ACC1) knockdown or the inhibition of ACC1 by TOFA induced COP1 expression, but palmatic acid, the end-product of de novo fatty acid synthesis pathway, reversed TOFA-induced COP1 expression. In addition, U73122, an inhibitor of phospholipase C that cleaves PIP2 into DAG and IP3, triggered COP1 expression. These data suggest that COP1 expression is mediated by cellular lipid state, and the lipid second messengers (PIP2 and DAG) are involved in the expression regulation of COP1. In contrast, the ectopic expression of COP1 greatly reduced pAMPK and pACC1 levels, but elevated fatty acid synthase (FASN) expression, leading to the increase of fatty acid (FA)/lipid synthesis. In sharp contrast, siRNA-mediated COP1 knockdown in cancer cells significantly increased pACC1 and pAMPK levels and reduced FASN expression, leading to decrease of lipid synthesis. The cell growth and proliferation was accordingly changed in response to the alterations of lipid synthesis. Altogether our data suggest that COP1 expression is regulated through the lipid second messenger mediated signaling, and the upregulated COP1 in turn enhances lipid synthesis, functioning as a positive feedback. Conclusion COP1 functions as a sensor of cellular lipid state and promoter of lipogenesis, facilitating tumorigenesis. Note: This abstract was not presented at the meeting. Citation Format: Chenfei Huang, Yiwen Bu, Deliang Cao. COP1 functions as a sensor of cellular lipids and regulator of lipogenesis in human cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1142. doi:10.1158/1538-7445.AM2015-1142

Abstract 1132: Gluconeogenesis, lipogenesis, and HBV replication are commonly regulated by PGC-1α-dependent pathway

Abstract Peroxisome proliferator-activated receptor-γ coactivator 1 (PGC-1α), a major metabolic regulator of gluconeogenesis and lipogenesis, is known to be strongly induced to coactivate HBV gene expression in the liver of fasting mice. In this study, we found that the combination of 8-Br-cAMP and glucocorticoids showed the synergistic induction of PGC-1α and its downstream gene expression, including the expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). Moreover, HBV corepromoter activity was synergistically enhanced by the combination of 8-Br-cAMP and glucocorticoid treatment. Graptopetalum paraguayense (GP), a herbal medicine, is commonly used in Taiwan to treat liver disorders. Here, we found that a partially purified fraction of GP (named HH-F3) dose dependently suppressed 8-Br-cAMP/glucocorticoid-induced G6Pase, PEPCKand PGC-1α expression as well as suppressed HBV core promoter activity. Additionally, HH-F3 blocked HBV core promoter activity via the inhibition of PGC-1α expression. The ectopic expression of PGC-1α effectively reversed the HH-F3-mediated inhibition of HBV core promoter activity.HH-F3-reduced HBV surface antigen expression, HBV mRNA production, core protein level, and HBV replication were drastically rescued by ectopically expressed PGC-1α. In addition, HH-F3 could also inhibit fatty acid synthase (FASN) expression as well as decrease lipid accumulation by the down-regulation of PGC-1α in human hepatocarcinoma cell lines. In conclusion, HH-F3 could inhibit HBV replication, gluconeogenesis, and lipogenesis through the down-regulation of PGC-1α. Our study indicates that targeting PGC-1α may be a novel therapeutic strategy for HBV infection. Together, HH-F3mighthave potential use for the treatment of chronic hepatitis B patients with associated metabolic syndrome. Citation Format: Wei-Hsiang Hsu, Hong-Jhih Jhuang, Chi-Ying Huang. Gluconeogenesis, lipogenesis, and HBV replication are commonly regulated by PGC-1α-dependent pathway. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1132. doi:10.1158/1538-7445.AM2015-1132

A Compartmental Comparison of Major Lipid Species in a Coral-Symbiodinium Endosymbiosis: Evidence that the Coral Host Regulates Lipogenesis of Its Cytosolic Lipid Bodies

The lipid body (LB) formation in the host coral gastrodermal cell cytoplasm is a hallmark of the coral-Symbiodinium endosymbiosis, and such lipid-based entities are not found in endosymbiont-free cnidarian cells. Therefore, the elucidation of lipogenesis regulation in LBs and how it is related to the lipid metabolism of the host and endosymbiont could provide direct insight to understand the symbiosis mechanism. Herein, the lipid composition of host cells of the stony coral Euphyllia glabrescens, as well as that of their cytoplasmic LBs and in hospite Symbiodinium populations, was examined by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS), and six major lipid species were identified: wax esters, sterol esters, triacylglycerols, cholesterols, free fatty acids, and phospholipids. Their concentrations differed significantly between host coral cells, LBs, and Symbiodinium, suggesting compartmental regulation. WE were only present in the host coral and were particularly highly concentrated in LBs. Amongst the four species of WE, the monoene R = C18:1/R = C16 was found to be LB-specific and was not present in the host gastrodermal cell cytoplasm. Furthermore, the acyl pool profiles of the individual LB lipid species were more similar, but not equal to, those of the host gastrodermal cells in which they were located, indicating partially autonomous lipid metabolism in these LBs. Nevertheless, given the overall similarity in the host gastrodermal cell and LB lipid profiles, these data suggest that a significant portion of the LB lipids may be of host coral origin. Finally, lipid profiles of the in hospite Symbiodinium populations were significantly distinct from those of the cultured Symbiodinium, potentially suggesting a host regulation effect that may be fundamental to lipid metabolism in endosymbiotic associations involving clade C Symbiodinium.

The CREB coactivator CRTC2 controls hepatic lipid metabolism by regulating SREBP1.

Abnormal accumulation of triglycerides in the liver, caused in part by increased de novo lipogenesis, results in non-alcoholic fatty liver disease and insulin resistance. Sterol regulatory element-binding protein 1 (SREBP1), an important transcriptional regulator of lipogenesis, is synthesized as an inactive precursor that binds to the endoplasmic reticulum (ER). In response to insulin signalling, SREBP1 is transported from the ER to the Golgi in a COPII-dependent manner, processed by proteases in the Golgi, and then shuttled to the nucleus to induce lipogenic gene expression; however, the mechanisms underlying enhanced SREBP1 activity in insulin-resistant obesity and diabetes remain unclear. Here we show in mice that CREB regulated transcription coactivator 2 (CRTC2) functions as a mediator of mTOR signalling to modulate COPII-dependent SREBP1 processing. CRTC2 competes with Sec23A, a subunit of the COPII complex, to interact with Sec31A, another COPII subunit, thus disrupting SREBP1 transport. During feeding, mTOR phosphorylates CRTC2 and attenuates its inhibitory effect on COPII-dependent SREBP1 maturation. As hepatic overexpression of an mTOR-defective CRTC2 mutant in obese mice improved the lipogenic program and insulin sensitivity, these results demonstrate how the transcriptional coactivator CRTC2 regulates mTOR-mediated lipid homeostasis in the fed state and in obesity.

Linking diet to acne metabolomics, inflammation, and comedogenesis: an update.

Acne vulgaris, an epidemic inflammatory skin disease of adolescence, is closely related to Western diet. Three major food classes that promote acne are: 1) hyperglycemic carbohydrates, 2) milk and dairy products, 3) saturated fats including trans-fats and deficient ω-3 polyunsaturated fatty acids (PUFAs). Diet-induced insulin/insulin-like growth factor (IGF-1)-signaling is superimposed on elevated IGF-1 levels during puberty, thereby unmasking the impact of aberrant nutrigenomics on sebaceous gland homeostasis. Western diet provides abundant branched-chain amino acids (BCAAs), glutamine, and palmitic acid. Insulin and IGF-1 suppress the activity of the metabolic transcription factor forkhead box O1 (FoxO1). Insulin, IGF-1, BCAAs, glutamine, and palmitate activate the nutrient-sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), the key regulator of anabolism and lipogenesis. FoxO1 is a negative coregulator of androgen receptor, peroxisome proliferator-activated receptor-γ (PPARγ), liver X receptor-α, and sterol response element binding protein-1c (SREBP-1c), crucial transcription factors of sebaceous lipogenesis. mTORC1 stimulates the expression of PPARγ and SREBP-1c, promoting sebum production. SREBP-1c upregulates stearoyl-CoA- and Δ6-desaturase, enhancing the proportion of monounsaturated fatty acids in sebum triglycerides. Diet-mediated aberrations in sebum quantity (hyperseborrhea) and composition (dysseborrhea) promote Propionibacterium acnes overgrowth and biofilm formation with overexpression of the virulence factor triglyceride lipase increasing follicular levels of free palmitate and oleate. Free palmitate functions as a “danger signal,” stimulating toll-like receptor-2-mediated inflammasome activation with interleukin-1β release, Th17 differentiation, and interleukin-17-mediated keratinocyte proliferation. Oleate stimulates P. acnes adhesion, keratinocyte proliferation, and comedogenesis via interleukin-1α release. Thus, diet-induced metabolomic alterations promote the visible sebofollicular inflammasomopathy acne vulgaris. Nutrition therapy of acne has to increase FoxO1 and to attenuate mTORC1/SREBP-1c signaling. Patients should balance total calorie uptake and restrict refined carbohydrates, milk, dairy protein supplements, saturated fats, and trans-fats. A paleolithic-like diet enriched in vegetables and fish is recommended. Plant-derived mTORC1 inhibitors and ω-3-PUFAs are promising dietary supplements supporting nutrition therapy of acne vulgaris.

Ethanol-induced hepatic steatosis is modulated by glycogen level in the liver

Alcoholic liver disease (ALD) is a major health problem worldwide and hepatic steatosis is an early response to alcohol consumption. Fat and glycogen are two major forms of energy storage in the liver; however, whether glycogen metabolism in the liver impacts alcohol-induced steatosis has been elusive. In this study, we used a mouse model with overexpression of PPP1R3G in the liver to dissect the potential role of glycogen on alcohol-induced fatty liver formation. PPP1R3G is a regulatory subunit of protein phosphatase 1 and stimulates glycogenesis in the liver. Chronic and binge ethanol (EtOH) feeding reduced glycogen level in the mouse liver and such inhibitory effect of EtOH was reversed by PPP1R3G overexpression. In addition, PPP1R3G overexpression abrogated EtOH-induced elevation of serum levels of alanine aminotransferase and aspartate aminotransferase, increase in liver triglyceride concentration, and lipid deposition in the liver. EtOH-stimulated sterol regulatory element-binding protein (SREBP)-1c, a master regulator of lipogenesis, was also reduced by PPP1R3G overexpression in vivo. In AML-12 mouse hepatocytes, PPP1R3G overexpression could relieve EtOH-induced lipid accumulation and SREBP-1c stimulation. In conclusion, our data indicate that glycogen metabolism is closely linked to EtOH-induced liver injury and fatty liver formation.

Long term vitamin A restriction improves meat quality parameters and modifies gene expression in Iberian pigs.

Vitamin A is a key regulator of gene expression, influencing adipogenesis and lipid metabolism in animal tissues. This experiment was conducted to assess the effect of dietary vitamin A level and administration time on productive traits, intramuscular fat (IMF) content in ham muscles, tissue fatty acid composition, and expression of a panel of adipogenic and lipogenic candidate genes in Iberian pigs. Sixty piglets of 16.3 kg (SD = 2.5 kg) live weight (LW) were either fed a vitamin A-enriched diet (10,000 IU vitamin A/kg; CONTROL, n = 20) or a diet without supplemented vitamin A, applied from 16.3 kg (SD = 2.5 kg; early restriction group, ER, n = 20) or from an average weight of 35.8 kg (SD = 3.1 kg; late restriction group, LR, n = 20). Two slaughters were performed when pigs reached the averaged weights of 101.4 (SD = 4.1 kg) and 157.9 kg LW (SD = 7 kg) and samples from liver, heart, and backfat were obtained in both sacrifice times. In addition, ham subcutaneous fat and Semimembranosus (SM) and Biceps Femoris (BF) muscles were sampled at the last sacrifice. Dietary vitamin A level produced no effect on carcass traits in any of the harvests, while a small effect was observed on fatty acid composition in backfat at 101.4 kg LW. However, at 157.9 kg LW, the ER and LR groups showed higher MUFA content and lower SFA content in backfat, ham fat, and IMF (P < 0.01). In IMF, a decrease in n-6/n-3 PUFA ratio was observed in the restricted groups (P < 0.005). Intramuscular fat content in SM muscle was greater (P < 0.05) in the ER group than in the CONTROL and LR groups, while no difference was detected in BF muscle. Little effect of dietary vitamin A was observed in liver. Regarding changes in gene expression, ACSL4, CEBPB, and IGF1 genes were upregulated (P < 0.0001, P < 0.0001, and P < 0.05, respectively) in the ER group in hepatic tissue, whereas CRABPII and SCD genes were upregulated (P < 0.05) in the same group in adipose tissue. On the other hand, was downregulated ( < 0.05) in the ER group in adipose tissue. Results found in this experiment show that long-term restriction of dietary vitamin A has a positive effect on nutritional and sensorial parameters of ham meat. Moreover, gene expression results were consistent with the vitamin A transcriptional regulation of adipogenesis and lipogenesis and with the changes observed in meat and fat composition.

Molecular cloning, characterization and expression of the energy homeostasis-associated gene in piglet.

The energy homeostasis-associated (Enho) gene encodes a secreted protein, adropin, which regulates the expression of hepatic lipogenic genes and adipose tissue peroxisome proliferator-activated receptor γ, a major regulator of lipogenesis. In the present study, the porcine (Sus scrofa) homologue of the Enho gene, which was named pEnho, was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) using oligonucleotide primers derived from in silico sequences. The gene sequence was submitted into the GenBank of NCBI, and the access number is GQ414763. The pEnho encodes a protein of 76 amino acids which shows 75% similarity to Homo sapiens adropin. The expression profile of pEnho in tissues (liver, muscle, anterior jejunum, posterior jejunum, and ileum) was determined by quantitative real-time RT-PCR. pEnho was localized on porcine chromosome 10 and no introns were found. In conclusion, pEnho was cloned and analysed with the aim of increasing knowledge about glucose and lipid metabolism in piglets and helping to promote the health and growth of piglets through adropin regulation.

Tumor suppressor Menin acts as a corepressor of LXRα to inhibit hepatic lipogenesis

Menin, encoded by the MEN1 gene, was initially identified as a tumor suppressor for endocrine neoplasia. Our previous report showed that Menin enhances PPARα transactivity preventing triglyceride accumulation in the liver. Here, we further explore the role of Menin in liver steatosis. Transient transfection assays demonstrate that Menin inhibits the transcriptional activity of nuclear receptor liver X receptor α (LXRα). Accordingly, Menin overexpression results in reduced expression of LXRα target genes, such as lipogenic enzymes including SREBP-1c, FASN and SCD-1. Co-immunoprecipitation assays revealed physical interaction between Menin and LXRα. Collectively, our data suggest that Menin acts as a novel corepressor of LXRα and functions as a negative regulator of hepatic lipogenesis.

The Regulation of Lipid Deposition by Insulin in Goose Liver Cells Is Mediated by the PI3K-AKT-mTOR Signaling Pathway.

BackgroundWe previously showed that the fatty liver formations observed in overfed geese are accompanied by the activation of the PI3K-Akt-mTOR pathway and an increase in plasma insulin concentrations. Recent studies have suggested a crucial role for the PI3K-Akt-mTOR pathway in regulating lipid metabolism; therefore, we hypothesized that insulin affects goose hepatocellular lipid metabolism through the PI3K-Akt-mTOR signaling pathway.MethodsGoose primary hepatocytes were isolated and treated with serum-free media supplemented with PI3K-Akt-mTOR pathway inhibitors (LY294002, rapamycin, and NVP-BEZ235, respectively) and 50 or 150 nmol/L insulin.ResultsInsulin induced strong effects on lipid accumulation as well as the mRNA and protein levels of genes involved in lipogenesis, fatty acid oxidation, and VLDL-TG assembly and secretion in primary goose hepatocytes. The stimulatory effect of insulin on lipogenesis was significantly decreased by treatment with PI3K-Akt-mTOR inhibitors. These inhibitors also rescued the insulin-induced down-regulation of fatty acid oxidation and VLDL-TG assembly and secretion.ConclusionThese findings suggest that the stimulatory effect of insulin on lipid deposition is mediated by PI3K-Akt-mTOR regulation of lipogenesis, fatty acid oxidation, and VLDL-TG assembly and secretion in goose hepatocytes.

Regulation of lipogenesis in human hepatocytes by androgens, glucocorticoids, and 5[alpha]-reductase

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Abstract P1-08-08: Reduction of HER2-associated lipogenic phenotype by docosahexaenoic acid (DHA) induces apoptosis in breast tumor cells harboring HER2 overexpression

Abstract The lipogenic phenotype is associated with oncogenic transformation and malignancy in the cancer setting. Our hypothesis is that the oncogenic nature of lipogenesis depends on the expression of HER2 oncogene, and its modulation by docosahexaenoic acid-DHA, might induce apoptosis in breast tumor cells with HER2 overexpression. To evaluate if the lipogenic phenotype might be induced by HER2 overexpression, we used a oncogenic transformation cell model in which, cells were engineered to overexpress HER-2 receptor (HB4aC5.2), but are identical to their parental strain (HB4a) in all other aspects, permitting an specific analysis of enhanced HER-2 effects. Toward this end the lipogenesis profiling was characterized, evaluating several molecular features, including synthesis (FASN), uptake(CD36), transport(FABP4) and storage(DGAT) of FA by RT-PCR and lipogenic regulatory pathways (mTOR, DEPTOR, SREBP1 and PPARγ) in both cells. Lipogenic contribution to lipid rafts formation, which is necessary to HER2 receptor location and activation in the cell membrane, was evaluated by gas chromatography and confocal microscopy. The influence of HER2 overexpression and lipogenic phenotype on proteins activated by HER-2 (AKT, ERK1/2 and FASN) was analyzed by western blot. Next, HB4a and HB4aC5.2 cells were treated, alone or in combination, with DHA, Trastuzumab (anti-HER2), and GW9662 (PPARγ inhibitor) for 72h, and the above experiments were repeated. Cell death was analyzed by flow cytometry and confocal microscopy. Results: In HB4aC5.2 cells, the oncogenic transformation by HER2 overexpression was associated with a lipogenic phenotype, which contributed to increase of lipid rafts formation, activation of survival and proliferation signals, as compared to HB4a normal cells (p&amp;lt;0.001). It is believed that PPARγ is the main regulator of cell lipogenesis. However, our data have shown that mTOR/SREBP pathway, exclusively mTORC1, was decreased concomitantly to increase of DEPTOR gene expression and AKT activation, in HB4aC5.2 cells. Also, the treatment with GW9662 did not change the expression of lipogenic genes, suggesting that lipogenesis seems independent of PPARγ activation, and that HER-2 overexpressing cells may use alternative mechanisms to maintain the lipogenic phenotype. DEPTOR is overexpressed in white adipose tissue and is associated with regulation of lipogenesis. Moreover, DEPTOR overexpression suppresses S6K1 but, by relieving feedback inhibition from mTORC1 to PI3K signaling, activates Akt. In HB4aC5.2 cells, only the DHA treatment decreased the lipogenic phenotype, DEPTOR expression, disrupted lipid raft, inhibited HER-2 signaling, and induced apoptosis (p&amp;lt;0.001). In addition the combined treatment using DHA and Trastuzumab increased cell death. Conclusion: We show that lipogenic phenotype was associated with HER-2 in breast cancer, can be induced early in the oncogenic transformation, and it seems important to promote survival and proliferation. Otherwise, Its modulation by DHA increased death in tumor cells, suggesting this kind of FA may represent a useful tool for controlling the HER2-positive breast cancer. Citation Format: Graziela R Ravacci, Maria M Brentani, William Festuccia, Tharcisio Tortelli, Angela F Waitzberg, Dan L Waitzberg. Reduction of HER2-associated lipogenic phenotype by docosahexaenoic acid (DHA) induces apoptosis in breast tumor cells harboring HER2 overexpression [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-08-08.