Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0015695 (fatty liver)
 13,941 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The use of near-infrared reflectance spectroscopy (NIRS) on a meat product is described in this report. The aim of the study was to develop calibration equations to predict the chemical composition of goose fatty liver (foie gras) with lipid contents greater than 40% of the fresh pate. Spectra of 52 foie gras samples were collected in the visible and NIR region (400 to 2,498 nm). Calibration equations were computed for DM, CP, lipids and fatty acids using modified partial least-squares regression. R2 values were high for the total lipid content (0.805) and DM (0.908) but were low for ash (0.151) and relatively low for protein content (0.255). For the major fatty acids, R2 ranged from 0.886 for palmitic acid to 0.988 for oleic acid. Oleic acid, the main fatty acid of the liver, and the stearic acid had higher R2 values than the less represented fatty acids. This study suggests that the NIRS technique can be used to predict lipid content and the fatty acid composition of goose fatty livers, but calibration must be built on a larger number of samples to generate accurate predictions.
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PMID:The use of near-infrared reflectance spectroscopy in the prediction of the chemical composition of goose fatty liver. 1173 80

Liver fatty acid-binding protein (L-Fabp) is an abundant cytosolic lipid-binding protein with broad substrate specificity, expressed in mammalian enterocytes and hepatocytes. We have generated mice with a targeted deletion of the endogenous L-Fabp gene and have characterized their response to alterations in hepatic fatty acid flux following prolonged fasting. Chow-fed L-Fabp-/- mice were indistinguishable from wild-type littermates with regard to growth, serum and tissue lipid profiles, and fatty acid distribution within hepatic complex lipid species. In response to 48-h fasting, however, wild-type mice demonstrated a approximately 10-fold increase in hepatic triglyceride content while L-Fabp-/- mice demonstrated only a 2-fold increase. Hepatic VLDL secretion was decreased in L-Fabp-/- mice suggesting that the decreased accumulation of hepatic triglyceride was not the result of increased secretion. Fatty acid oxidation, as inferred from serum beta-hydroxybutyrate levels, was increased in response to fasting, although the increase in L-Fabp-/- mice was significantly reduced in comparison to wild-type controls, despite comparable induction of PPAR alpha target genes. Studies in primary hepatocytes revealed indistinguishable initial rates of oleate uptake, but longer intervals revealed reduced rates of uptake in fasted L-Fabp-/- mice. Oleate incorporation into cellular triglyceride and diacylglycerol was reduced in L-Fabp-/- mice although incorporation into phospholipid and cholesterol ester was no different than wild-type controls. These data point to an inducible defect in fatty acid utilization in fasted L-Fabp-/- mice that involves targeting of substrate for use in triglyceride metabolism.
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PMID:Decreased hepatic triglyceride accumulation and altered fatty acid uptake in mice with deletion of the liver fatty acid-binding protein gene. 1453 95

Studies were conducted to explore altered substrate utilization and metabolism in GLUT4 null mice. Liver fatty acid synthase mRNA and fatty acid synthesis rates were dramatically increased in GLUT4 null mice compared with control mice and were supported by increased rates of the pentose phosphate pathway oxidative phase and sterol regulatory binding protein mRNA expression. Increased GLUT2 protein content, glucokinase mRNA, and glucose-6-phosphate in GLUT4 null mice may provide substrate for the enhanced fatty acid synthesis. Increased fatty acid synthesis, however, did not lead to hepatic triglyceride accumulation in GLUT4 null mice because of increased hepatic triglyceride secretion rates. GLUT4 null mice rapidly cleared orally administered olive oil, had reduced serum triglyceride concentrations in the fed and the fasted state, and increased skeletal muscle lipoprotein lipase when compared with controls. Oleate oxidation rates were increased in GLUT4 null skeletal muscle in association with mitochondrial hyperplasia/hypertrophy. This study demonstrated that GLUT4 null mice had increased hepatic glucose uptake and conversion into triglyceride for subsequent use by muscle. The ability of GLUT4 null mice to alter hepatic carbohydrate and lipid metabolism to provide proper nutrients for peripheral tissues may explain (in part) their ability to resist diabetes when fed a normal diet.
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PMID:Altered hepatic and muscle substrate utilization provoked by GLUT4 ablation. 1579 30

Lipid droplets (LDs) are intracellular storage sites of neutral lipids, which accumulate in fatty liver disease. Here, we investigated the effects of fatty acids and glucose on LD formation in a cultured human hepatocyte, HuH7, by adding them to culture media. Fatty acids with carbohydrate chains C12-C18 efficiently induced LDs, but those of C8 and C10 were ineffective. Glucose did not induce LD formation even in the presence of insulin. Oleic acid induced significant increases in cellular neutral lipids, and cell fractionation revealed that most of the newly synthesized neutral lipids were concentrated in LDs together with LD proteins. The LD formation was not abrogated by removal of medium glucose but was significantly inhibited by an ACSL inhibitor, triacsin C. These results demonstrate that long-chain fatty acids contribute to LD formation to a greater extent than glucose, possibly by being taken up into the cells, activated by ACSL, reconstituted into neutral lipids and then stored in LDs. Pregnenolone and lithium did not suppress oleic acid-dependent LD formation, despite previous reports of their ability to inhibit LD formation in macrophages and adipocytes suggesting differences among LD formations in these cells.
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PMID:Long-chain fatty acids induce lipid droplet formation in a cultured human hepatocyte in a manner dependent of Acyl-CoA synthetase. 1707 10

Stearoyl-CoA desaturase-1 (SCD1), a critical regulator of energy metabolism, catalyzes the synthesis of monounsaturated fats. To understand the tissue-specific role of SCD1 in energy homeostasis, we used Cre-lox technology to generate mice with a liver-specific knockout of Scd1 (LKO). LKO mice were protected from high-carbohydrate, but not high-fat (HF), diet-induced adiposity and hepatic steatosis. Additionally, on a high-sucrose, very low-fat (HSVLF) diet, lipogenesis and levels of nuclear SREBP-1 and ChREBP were significantly decreased in the livers of LKO relative to Scd1(lox/lox) (Lox) mice. HSVLF feeding in LKO mice caused hypoglycemia and hepatic carbohydrate reduction due to an impairment of gluconeogenesis. Oleate, but not stearate, supplementation normalized adiposity, gluconeogenesis, triglyceride secretion, and hepatic lipogenesis of LKO mice. These results indicate that hepatic SCD1 expression (and thus, oleate) is required for carbohydrate-induced adiposity, but SCD1 inhibition in extrahepatic tissues is required to protect mice from HF-induced obesity and insulin resistance.
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PMID:Hepatic stearoyl-CoA desaturase-1 deficiency protects mice from carbohydrate-induced adiposity and hepatic steatosis. 1805 17

Delivery of free fatty acids to the liver in nonalcoholic fatty liver disease (NAFLD) may render hepatocytes more vulnerable to glycochenodeoxycholic acid (GCDCA)-induced apoptosis. Fat overloading was induced in HepG2-Ntcp cells and primary rat hepatocytes by incubation with palmitic or oleic acid. Apoptosis was quantified by measuring caspase 3/7 activity and transcription of interleukin (IL) 8 and IL-22 by quantitative real-time PCR. Oleic acid (500 microM) alone did not induce apoptosis, while palmitic acid (500 microM) increased apoptosis 5-fold. GCDCA did not induce significant apoptosis at low micromolar concentrations (5-30 microM) in non-steatotic cells. However, at the same concentrations, GCDCA increased apoptosis 3-fold in oleic acid-pretreated HepG2-Ntcp cells and 3.5-fold in primary rat hepatocytes. Pretreatment with oleic acid increased GCDCA-induced gene transcription of the proinflammatory cytokines IL-8 and IL-22 5-fold and 19-fold, respectively. Thus, low levels of cholestasis normally not considered harmful could advance liver injury in patients with NAFLD.
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PMID:Free fatty acids sensitize hepatocytes to bile acid-induced apoptosis. 1845 8

We investigated the effects of stearic acid (saturated), oleic acid (monounsaturated), linoleic acid (n-6 polyunsaturated), and alpha-linolenic acid (n-3 polyunsaturated) on lipid metabolism in a hepatocyte-derived cell line, HepG2. HepG2 cells were cultured in medium supplemented with either stearic acid (0.1% w/v), oleic acid (0.1% v/v), linoleic acid (0.1% v/v), or alpha-linolenic acid (0.1% v/v). After 24 h, expression of lipid metabolism-associated genes was evaluated by real-time PCR. Alpha-linolenic acid showed a suppressive effect on the hepatic fatty acid de novo synthesis and fatty acid oxidation pathways, while linoleic acid also showed a tendency to suppress these pathways although the effect was weaker. Moreover, alpha-linolenic acid enhanced the expression of enzymes associated with reactive oxygen species (ROS) elimination. In contrast, oleic acid tended to promote fatty acid synthesis and oxidation. In conclusion, alpha-linolenic acid and linoleic acid may be expected to ameliorate hepatic steatosis by downregulating fatty acid de novo synthesis and fatty acid oxidation, and by upregulating ROS elimination enzymes. Oleic acid had no distinct effects for improving steatosis or oxidative stress.
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PMID:The effects of unsaturated fatty acids on lipid metabolism in HepG2 cells. 1883 Jul 74

Fatty acids stimulate lipid accumulation in parallel with increased expression of adipose differentiation-related protein (ADRP) in liver cells. Although it is generally considered that the fatty acid effect on ADRP expression is mediated by peroxisome proliferator-activated receptors (PPARs), we identified here an additional molecular mechanism using the NMuLi mouse liver nonparenchymal cell line, which expresses PPARgamma and delta but not alpha. Oleic acid (OA) and specific ligands for PPARgamma and -delta stimulated ADRP expression as well as the -2,090-bp ADRP promoter activity which encompasses the PPAR response element (PPRE) adjacent to an Ets/activator protein (AP)-1 site. When the AP-1 site was mutated, OA failed to stimulate the activity despite the presence of the PPRE, whereas ligands for PPARgamma and -delta did stimulate it and so did a PPARalpha ligand under the coexpression of PPARalpha. DNA binding of AP-1 was stimulated by OA but not by PPAR ligands. Because we previously demonstrated that Pycnogenol (PYC), a French maritime pine bark extract, suppressed ADRP expression in macrophages partly by suppression of AP-1 activity, we tested the effect of PYC on NMuLi cells. PYC reduced the OA-induced ADRP expression along with suppression of lipid droplet formation. However, PYC neither suppressed the OA-stimulated ADRP promoter activity nor DNA binding of AP-1 but, instead, reduced the ADRP mRNA half-life. All these results indicate that the effect of OA on ADRP expression requires AP-1 as well as PPRE, and PYC suppresses the ADRP expression in part by facilitating mRNA degradation. PYC, a widely used dietary supplement, could be beneficial for the prevention of excessive lipid accumulation such as hepatic steatosis.
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PMID:Oleic acid-induced ADRP expression requires both AP-1 and PPAR response elements, and is reduced by Pycnogenol through mRNA degradation in NMuLi liver cells. 1938 73

Intracellular lipid droplets are associated with a myriad of afflictions including obesity, fatty liver disease, coronary artery disease, and infectious diseases (eg, HCV and tuberculosis). To develop high-content analysis (HCA) techniques to analyze lipid droplets and associated proteins, primary human preadipocytes were plated in 96-well dishes in the presence of rosiglitazone (rosi), a PPAR-(c) agonist that promotes adipogenesis. The cells were then labeled for nuclei, lipid droplets, and proteins such as perilipin, protein kinase C (PKC), and hormone-sensitive lipase (HSL). The cells were imaged via automated digital microscopy and algorithms were developed to quantify lipid droplet (Lipid Droplet algorithm) and protein expression and colocalization (Colocalization algorithm). The algorithms, which were incorporated into Vala Science Inc's CyteSeer((R)) image cytometry program, quantified the rosi-induced increases in lipid droplet number, size, and intensity, and the expression of perilipin with exceptional consistency (Z' values of 0.54-0.71). Regarding colocalization with lipid droplets, Pearson's correlation coefficients of 0.38 (highly colocalized), 0.16 (moderate), and -0.0010 (random) were found for perilipin, PKC, and HSL, respectively. For hepatocytes (AML12, HuH-7, and primary cells), the algorithms also quantified the stimulatory and inhibitory effect of oleic acid and triacsin C on lipid droplets (Z's > 0.50) and ADFP expression/colocalization. Oleic acid-induced lipid droplets in HeLa cells and macrophages (THP-1) were also well quantified. The results suggest that HCA techniques can be utilized to quantify lipid droplets and associated proteins in many cell models relevant to a variety of diseases.
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PMID:Quantification of lipid droplets and associated proteins in cellular models of obesity via high-content/high-throughput microscopy and automated image analysis. 1989 45

The upsurge in prevalence of obesity has spawned an epidemic of nonalcoholic fatty liver disease (NAFLD). Previously, we identified a sequence variant (I148M) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) that confers susceptibility to both hepatic triglyceride (TG) deposition and liver injury. To glean insights into the biological role of PNPLA3, we examined the molecular mechanisms by which nutrient status controls hepatic expression of PNPLA3. PNPLA3 mRNA levels, which were low in fasting animals, increased approximately 90-fold with carbohydrate feeding. The increase was mimicked by treatment with a liver X receptor (LXR) agonist and required the transcription factor SREBP-1c. The site of SREBP-1c binding was mapped to intron 1 of Pnpla3 using chromatin immunoprecipitation and electrophoretic mobility shift assays. SREBP-1c also promotes fatty acid synthesis by activating several genes encoding enzymes in the biosynthetic pathway. Addition of fatty acids (C16:0, C18:1, and C18:2) to the medium of cultured hepatocytes (HuH-7) increased PNPLA3 protein mass without altering mRNA levels. The posttranslational increase in PNPLA3 levels persisted after blocking TG synthesis with triascin C. Oleate (400 muM) treatment prolonged the half-life of PNPLA3 from 2.4 to 6.7 h. These findings are consistent with nutritional control of PNPLA3 being effected by a feed-forward loop; SREBP-1c promotes accumulation of PNPLA3 directly by activating Pnpla3 transcription and indirectly by inhibiting PNPLA3 degradation through the stimulation of fatty acid synthesis.
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PMID:A feed-forward loop amplifies nutritional regulation of PNPLA3. 2038 13


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