Oleic Acid Uptake Research Articles

Diflunisal activates AMP-activated protein kinase and stimulates glucose uptake, glycolysis and oxidation of glucose and oleic acid in skeletal muscle cells

Diflunisal activates AMP-activated protein kinase and stimulates glucose uptake, glycolysis and oxidation of glucose and oleic acid in skeletal muscle cells

Interplay between Cultured Human Osteoblastic and Skeletal Muscle Cells: Effects of Conditioned Media on Glucose and Fatty Acid Metabolism.

The interplay between skeletal muscle and bone is primarily mechanical; however, biochemical crosstalk by secreted mediators has recently gained increased attention. The aim of this study was to investigate metabolic effects of conditioned medium from osteoblasts (OB-CM) on myotubes and vice versa. Human skeletal muscle cells incubated with OB-CM showed increased glucose uptake and oxidation, and mRNA expression of the glucose transporter (GLUT) 1, while fatty acid uptake and oxidation, and mRNA expression of the fatty acid transporter CD36 were decreased. This was supported by proteomic analysis, where expression of proteins involved in glucose uptake, glycolytic pathways, and the TCA cycle were enhanced, and expression of several proteins involved in fatty acid metabolism were reduced. Similar effects on energy metabolism were observed in human bone marrow stromal cells differentiated to osteoblastic cells incubated with conditioned medium from myotubes (SKM-CM), with increased glucose uptake and reduced oleic acid uptake. Proteomic analyses of the two conditioned media revealed many common proteins. Thus, our data may indicate a shift in fuel preference from fatty acid to glucose metabolism in both cell types, induced by conditioned media from the opposite cell type, possibly indicating a more general pattern in communication between these tissues.

Energy metabolism in skeletal muscle cells from donors with different body mass index.

Obesity and physical inactivity have a profound impact on skeletal muscle metabolism. In the present work, we have investigated differences in protein expression and energy metabolism in primary human skeletal muscle cells established from lean donors (BMI<25kg/m2) and individuals with obesity (BMI>30kg/m2). Furthermore, we have studied the effect of fatty acid pretreatment on energy metabolism in myotubes from these donor groups. Alterations in protein expression were investigated using proteomic analysis, and energy metabolism was studied using radiolabeled substrates. Gene Ontology enrichment analysis showed that glycolytic, apoptotic, and hypoxia pathways were upregulated, whereas the pentose phosphate pathway was downregulated in myotubes from donors with obesity compared to myotubes from lean donors. Moreover, fatty acid, glucose, and amino acid uptake were increased in myotubes from individuals with obesity. However, fatty acid oxidation was reduced, glucose oxidation was increased in myotubes from subjects with obesity compared to cells from lean. Pretreatment of myotubes with palmitic acid (PA) or eicosapentaenoic acid (EPA) for 24h increased glucose oxidation and oleic acid uptake. EPA pretreatment increased the glucose and fatty acid uptake and reduced leucine fractional oxidation in myotubes from donors with obesity. In conclusion, these results suggest that myotubes from individuals with obesity showed increased fatty acid, glucose, and amino acid uptake compared to cells from lean donors. Furthermore, myotubes from individuals with obesity had reduced fatty acid oxidative capacity, increased glucose oxidation, and a higher glycolytic reserve capacity compared to cells from lean donors. Fatty acid pretreatment enhances glucose metabolism, and EPA reduces oleic acid and leucine fractional oxidation in myotubes from donor with obesity, suggesting increased metabolic flexibility after EPA treatment.

FABP5 controls macrophage alternative activation and allergic asthma by selectively programming long-chain unsaturated fatty acid metabolism.

Fatty acids (FAs) are widely involved in diverse biological functions. In mice with myeloid-specific deletion of fatty acid-binding protein 5 (FABP5), OVA-induced allergic airway inflammation (AAI) is significantly exacerbated by increasing alternatively activated macrophages (M2). Fabp5 deficiency increases IL-4-induced M2 invitro. In macrophages, Fabp5 deletion causes significant accumulation of free long-chain unsaturated FAs, such as oleic acid, but does not cause detectable changes to other groups of FAs. Interestingly, excessive uptake of oleic acid aggravates AAI pathogenesis, with increased M2 polarization in bronchoalveolar lavage fluid. Informatics and mechanistic studies indicate that Fabp5 deficiency may reprogram metabolic pathways by enhancing FA β oxidation, tricarboxylic acid cycle, and oxidative phosphorylation, in addition to producing more ATP through activation of the PPARγ signaling pathway, reshaping macrophages in favor of M2 polarization. These results emphasize the importance of FABP5 and oleic acid in AAI, suggesting preventive and therapeutic strategies for allergic asthma.

Insulin prevents fatty acid induced increase of adipocyte size

ABSTRACT Metabolic disorders related to obesity are largely dependent on adipose tissue hypertrophy, which involves adipocyte hypertrophy and increased adipogenesis. Adiposize is regulated by lipid accumulation as a result of increased lipogenesis (mainly lipid uptake in mature adipocytes) and reduced lipolysis. Using realtime 2D cell culture analyses of lipid uptake, we show 1) that high glucose concentration (4.5 g/L) was required to accumulate oleic acid increasing lipid droplet size until unilocularisation similar to mature adipocytes in few days, 2) oleic acid reduced Peroxisome-Proliferator Activated Receptor Gamma (PPARG) gene transcription and 3) insulin counteracted oleic acid-induced increase of lipid droplet size. Although the lipolytic activity observed in high versus low glucose (1g/L) conditions was not altered, insulin was found to inhibit oleic acid induced gene transcription required for lipid storage such as CIDEC (Cell Death Inducing DFFA Like Effectors) and G0S2 (G0 switch gene S2), possibly through PPARA activity. Although this signaling pathway requires more detailed investigation, the results point out the differential mechanisms involved in the pro-adipogenic effect of insulin in absence versus its protective effect on adiposity in presence of oleic acid uptake.

3-tert-Butyl-4-hydroxyanisole Impairs Hepatic Lipid Metabolism in Male Mice Fed with a High-Fat Diet.

3-tert-Butyl-4-hydroxyanisole (3-BHA), one of the widely used food antioxidants, has been found to act as a potential obesogen by promoting adipogenesis in vitro and inducing white adipose tissue development in vivo. Whether 3-BHA-induced visceral obesity was accompanied by a disruption of hepatic lipid homeostasis in mammals remained unclear. In this study, we evaluated the effect of 3-BHA on the development of nonalcoholic fatty liver disease (NAFLD) in male C57BL/6J mice. After 18 weeks of oral administration of 10 mg/kg 3-BHA, the mice fed with a high-fat diet (HFD) had higher hepatic triglyceride concentrations (0.32 mg/mg protein) and severer steatosis (1.57 for the NAFLD score) than the control ones. The in vivo hepatic lipid deposition disturbed by 3-BHA was transcriptionally regulated by the genes involved in lipid uptake, de novo lipogenesis, fatty acid oxidation, and lipid export. The in vitro studies further confirmed that 24 h of exposure to 50 μM 3-BHA could induce intracellular oleic acid (OA) uptake and triglyceride accumulation (1.5-fold of the OA control) in HepG2 cells. Lipidomic analysis indicated the perturbation of 3-BHA in the levels of 30 lipid species related to sphingolipids, glycerophospholipids, and glycerolipids under HFD conditions. The findings herein first revealed the disruption effect of 3-BHA on hepatic lipid homeostasis, thus exacerbating the development of HFD-induced NAFLD.

Retraction Note to: Effect of a high fat diet on lipid absorption and fatty acid transport in a rat model of short bowel syndrome

Long chain fatty acids (LCFAs) appear to be powerful stimulants for small bowel adaptation in patients with short bowel syndrome (SBS). However, the dietary lipid content may alter intestinal lipid transport. The aim of this study was to investigate the effects of a high fat diet (HFD) on in vivo lipid absorption and molecular and cellular mechanisms of LCFAs uptake by the remaining bowel. Male Sprague-Dawley rats (240–280) were randomly assigned to one of three groups: sham rats fed normal chow (sham-NC), SBS rats fed NC (SBS-NC) and SBS rats fed HFD (SBS-HFD). SBS rats underwent a 75% small bowel resection. Rats were sacrificed on day 3 or 14. Body weight, fat intake and fat clearance (total fecal fat) were measured twice a week. Fat absorbability was calculated as intake minus clearance and was expressed as percent of intake. Total RNA from the mucosa of duodenum, jejunum and ileum was extracted using TRIZOL Reagent. Northern blot analysis was performed to determine FAT/CD36 mRNA levels. Enterocyte LCFA transport was measured on day 14. LCFA uptake was determined by measuring cellular [3H]-oleate uptake over time (4–120 s). Mean (±SE) FAT/CD36 mRNA levels and oleate uptake kinetic parameters were analyzed using ANOVA. Fat absorbability diminished after bowel resection, suggesting fat malabsorption. Remaining bowel in SBS-NC rats responded by an increase in FAT/CD36 mRNA levels in the duodenum and ileum on day 3, and the duodenum and jejunum on day 14 compared to sham-NC animals, and was accompanied by an increase in enterocyte LCFA transport in all segments. Exposure to a HFD for 14 days resulted in significantly increased fat absorbability after 3 days compared to SBS-NC rats. However, FAT/CD36 mRNA levels (vs. SBS-NC) decreased in all segments on day 3. On day 14, FAT/CD36 mRNA levels were decreased in the duodenum and ileum and were accompanied by reduced oleate uptake by isolated enterocytes in the ileum (vs. SBS-NC). In a rat model of SBS, early high fat diet increased lipid absorptive capacity of the intestinal remnant as seen by increased fat absorbability. The main mechanisms of this effect may be an acceleration of structural intestinal adaptation resulting in an increased number of enterocytes. However, at molecular and cellular levels HFD decreased mucosal FAT/CD36 mRNA levels and oleic acid uptake by isolated enterocytes.

Effect of Green Tea Extract on the Luminal Uptake of Dioxin and Oleic Acid by the Intestinal Mucosa in a Rat Model

Effect of Green Tea Extract on the Luminal Uptake of Dioxin and Oleic Acid by the Intestinal Mucosa in a Rat Model

Chronic treatment with terbutaline increases glucose and oleic acid oxidation and protein synthesis in cultured human myotubes

ObjectiveIn vivo studies have reported several beneficial metabolic effects of β-adrenergic receptor agonist administration in skeletal muscle, including increased glucose uptake, fatty acid metabolism, lipolysis and mitochondrial biogenesis. Although these effects have been widely studied in vivo, the in vitro data are limited to mouse and rat cell lines. Therefore, we sought to discover the effects of the β2-adrenergic receptor agonist terbutaline on metabolism and protein synthesis in human primary skeletal muscle cells. MethodsHuman cultured myotubes were exposed to terbutaline in various concentrations (0.01–30 ​μM) for 4 or 96 ​h. Thereafter uptake of [14C]deoxy-D-glucose, oxydation of [14C]glucose and [14C]oleic acid were measured. Incorporation of [14C]leucine, gene expression by qPCR and proteomics analyses by mass spectrometry by the STAGE-TIP method were performed after 96 ​h exposure to 1 and 10 ​μM of terbutaline. ResultsThe results showed that 4 ​h treatment with terbutaline in concentrations up to 1 ​μM increased glucose uptake in human myotubes, but also decreased both glucose and oleic acid oxidation along with oleic acid uptake in concentrations of 10–30 ​μM. Moreover, administration of terbutaline for 96 ​h increased glucose uptake (in terbutaline concentrations up to 1 ​μM) and oxidation (1 ​μM), as well as oleic acid oxidation (0.1–30 ​μM), leucine incorporation into cellular protein (1–10 ​μM) and upregulated several pathways related to mitochondrial metabolism (1 ​μM). Data are available via ProteomeXchange with identifier PXD024063. ConclusionThese results suggest that β2-adrenergic receptor have direct effects in human skeletal muscle affecting fuel metabolism and net protein synthesis, effects that might be favourable for both type 2 diabetes and muscle wasting disorders.

The small molecule SERCA activator CDN1163 increases energy metabolism in human skeletal muscle cells

Background and objectiveA number of studies have highlighted muscle-specific mechanisms of thermogenesis involving futile cycling of Ca2+ driven by sarco (endo)plasmic reticulum Ca2+-ATPase (SERCA) and generating heat from ATP hydrolysis to be a promising strategy to counteract obesity and metabolic dysfunction. However, to the best of our knowledge, no experimental studies concerning the metabolic effects of pharmacologically targeting SERCA in human skeletal muscle cells have been reported. Thus, in the present study, we aimed to explore the effects of SERCA-activating compound, CDN1163, on energy metabolism in differentiated human skeletal muscle cells (myotubes). MethodsIn this study, we used primary myotube cultures derived from muscle biopsies of the musculus vastus lateralis and musculi interspinales from lean, healthy male donors. Energy metabolism in myotubes was studied using radioactive substrates. Oxygen consumption rate was assessed with the Seahorse XF24 bioanalyzer, whereas metabolic genes and protein expressions were determined by qPCR and immunoblotting, respectively. ResultsBoth acute (4 ​h) and chronic (5 days) treatment of myotubes with CDN1163 showed increased uptake and oxidation of glucose, as well as complete fatty acid oxidation in the presence of carbonyl cyanide 4-(trifluromethoxy)phenylhydrazone (FCCP). These effects were supported by measurement of oxygen consumption rate, in which the oxidative spare capacity and maximal respiration were enhanced after CDN1163-treatment. In addition, chronic treatment with CDN1163 improved cellular uptake of oleic acid (OA) and fatty acid β-oxidation. The increased OA metabolism was accompanied by enhanced mRNA-expression of carnitine palmitoyl transferase (CPT) 1B, pyruvate dehydrogenase kinase (PDK) 4, as well as increased AMP-activated protein kinase (AMPK)Thr172 phosphorylation. Moreover, following chronic CDN1163 treatment, the expression levels of stearoyl-CoA desaturase (SCD) 1 was decreased together with de novo lipogenesis from acetic acid and formation of diacylglycerol (DAG) from OA. ConclusionAltogether, these results suggest that SERCA activation by CDN1163 enhances energy metabolism in human myotubes, which might be favourable in relation to disorders that are related to metabolic dysfunction such as obesity and type 2 diabetes mellitus.

4-Hexylphenol influences adipogenic differentiation and hepatic lipid accumulation in vitro

Finding the potential environmental obesogens is crucial to explain the prevalence of obesity and the related pathologies. Increasing evidence has showed that many chemicals with endocrine disrupting effects can disturb lipid metabolism. Whether 4-hexylphenol (4-HP), a widely-used surfactant and a potential endocrine disrupting chemical (EDC), is associated to influence adipogenesis and hepatic lipid accumulation remained to be elucidated. In this study, both the 3T3-L1 differentiation model and oleic acid (OA)-treated HepG2 cells were used to investigate the effects of 4-HP on lipid metabolism, and the underlying estrogen receptor (ER)-involved mechanism was explored using MVLN assay, molecular docking simulation and the antagonist test. The results based on lipid droplet staining and triglyceride accumulation assay showed that 4-HP treatment promoted the adipogenic differentiation of 3T3-L1 cells and increased hepatic cellular OA accumulation in exposure concentration-dependent manners. The study on the elaborated transcription networks indicated that 4-HP activated peroxisome proliferator-activated receptor γ (PPARγ) as well as the subsequent adipogenic gene program in 3T3-L1 cells. This chemical also induced the increase of OA uptake and decreases of de novo lipogenesis and fatty acid oxidation in HepG2 cells. The agonistic activity of 4-HP in triggering ER-mediated pathway was shown to correlate with its perturbation in lipid metabolism, as evidenced by the enhanced development of mature lipid-laden adipocytes and suppression of excessive hepatic lipid accumulation upon its co-treatment with ER antagonist. Altogether, these findings provide new insights into the potential health impacts of 4-HP exposure as it may relate to obesity and nonalcoholic fatty liver disease.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Substrate oxidation in primary human skeletal muscle cells is influenced by donor age

Primary human myotubes represent an alternative system to intact skeletal muscle for the study of human diseases related to changes in muscle energy metabolism. This work aimed to study if fatty acid and glucose metabolism in human myotubes in vitro were related to muscle of origin, donor gender, age, or body mass index (BMI). Myotubes from a total of 82 donors were established from three different skeletal muscles, i.e., musculus vastus lateralis, musculus obliquus internus abdominis, and musculi interspinales, and cellular energy metabolism was evaluated. Multiple linear regression analyses showed that donor age had a significant effect on glucose and oleic acid oxidation after correcting for gender, BMI, and muscle of origin. Donor BMI was the only significant contributor to cellular oleic acid uptake, whereas cellular glucose uptake did not rely on any of the variables examined. Despite the effect of age on substrate oxidation, cellular mRNA expression of pyruvate dehydrogenase kinase 4 (PDK4) and peroxisome proliferator–activated receptor gamma coactivator 1 alpha (PPARGC1A) did not correlate with donor age. In conclusion, donor age significantly impacts substrate oxidation in cultured human myotubes, whereas donor BMI affects cellular oleic acid uptake.

Improvement and Metabolomics-Based Analysis of d-Lactic Acid Production from Agro-Industrial Wastes by Lactobacillus delbrueckii Submitted to Adaptive Laboratory Evolution.

To decrease d-lactic acid production cost, sugarcane molasses and soybean meal, low-cost agro-industrial wastes, were selected as feedstock. First, sugarcane molasses was used directly by Lactobacillus delbrueckii S-NL31, and the nutrients were released from soybean meal by protease hydrolysis. Subsequently, to ensure intensive substrate utilization and enhanced d-lactic acid production from sugarcane molasses and soybean meal, adaptation of L. delbrueckii S-NL31 to substrates was performed through adaptive laboratory evolution. After two-phase adaptive laboratory evolution, the evolved strain L. delbrueckii S-NL31-CM3-SBM with improved cell growth and d-lactic acid production on sugarcane molasses and soybean meal was obtained. To decipher the potential reasons for improved fermentation performance, a metabolomics-based approach was developed to profile the differences of intracellular metabolism between initial and evolved strain. The in-depth analysis elucidated how the key factors exerted influence on d-lactic acid biosynthesis. The results revealed that the enhancement of glycolysis pathway and cofactor supply was directly associated with increased lactic acid production, and the reinforcement of pentose phosphate pathway, amino acid metabolism, and oleic acid uptake improved cell survival and growth. These might be the main reasons for significantly improved d-lactic acid production by adaptive laboratory evolution. Finally, fed-batch simultaneous enzymatic hydrolysis of soybean meal and fermentation process by evolved strain resulted in d-lactic acid levels of 112.3 g/L, with an average production efficiency of 2.4 g/(L × h), a yield of 0.98 g/g sugar, and optical purity of 99.6%. The results show the applicability of d-lactic acid production in L. delbrueckii fed on agro-industrial wastes through adaptive laboratory evolution.

Pancreatic cancer cells show lower oleic acid oxidation and their conditioned medium inhibits oleic acid oxidation in human myotubes

Background/Objectives: We aimed to metabolically compare healthy primary human pancreatic epithelial cells (hPEC) to a pancreatic cancer cell line (PANC-1) and explore the effect on energy metabolism of exposing primary human myotubes to conditioned medium from hPEC and PANC-1 cells. MethodsDifferences in metabolism were examined with radiolabeled glucose, oleic acid and lactic acid, and by qPCR. Mass spectrometry-based proteomics was used to study global protein secretion from the two cell types. Pathway analyses were performed. ResultsPANC-1 cells tended to have higher glucose uptake, production of lactic acid, and glucose oxidation compared to hPEC cells. PANC-1 cells had higher uptake but lower oxidation of oleic acid, and mitochondrial reserve capacity from oleic acid was lower in PANC-1 cells. These differences in energy metabolism were reflected by differences in gene expressions and pathway analyses of the secretome. Conditioned medium from PANC-1 cells attenuated oleic acid oxidation in primary human myotubes. ConclusionsMetabolic characterization of the PANC-1 cells revealed a glycolytic phenotype since they had an active glucose oxidation. Furthermore, PANC-1 cells showed a lower oleic acid oxidation and secreted a high amount of proteins into conditioned medium that also induced a reduced oleic acid oxidation in myotubes.

Suppression of long chain acyl-CoA synthetase blocks intracellular fatty acid flux and glucose uptake in skeletal myotubes

Alterations in fatty acid metabolism are associated with impaired glucose uptake in skeletal muscle. Long-chain acyl-CoA synthetase (Acsl) 6 is the one of the Acsl isoforms expressed in skeletal muscle although its role in muscle energy metabolism has not been studied. Thus, the aims of this study were to investigate the role of Acsl6 in fatty acid partitioning and glucose uptake in differentiated skeletal myotubes using a siRNA-mediated knockdown approach. Compared with cells transfected with control siRNA, cells transfected with Acsl6 siRNA exhibited reduced intracellular triacylglycerol (TAG) accumulation. The initial rate of [1‑14C]‑oleic acid uptake was not altered while the incorporation of [1‑14C]‑acetic acids into total cellular lipids decreased under Acsl6 knockdown (p < 0.05). In a metabolic labeling study, Acsl6 suppression decreased the incorporation of [1‑14C]‑oleic acids and [1‑14C]‑acetic acids into TAG and diacylglycerol (DAG) (p < 0.05). During the chase period of a pulse-chase experiment, Acsl6 suppression increased the intracellular free fatty acids and decreased the fatty acid channeling toward the reacylation of TAG (p < 0.05). The incorporation of the labeled fatty acids into acid-soluble metabolites, β-oxidation product, was not changed under Acsl6 knockdown. Acsl6 siRNA decreased the insulin-induced uptake of [1‑14C]‑2‑deoxyglucose (p < 0.05) but did not change the glucose uptake in the presence of acipimox, inhibitor of lipolysis. Suppression of Acsl6 deteriorated Akt phosphorylation and Glut4 mRNA expression in response to insulin. These results suggest that Acsl6 activates and channels fatty acids toward anabolic pathways and has a role in glucose and fatty acid cycling through the re-esterification of fatty acids in skeletal muscle.

Utilization of lactic acid in human myotubes and interplay with glucose and fatty acid metabolism

Once assumed only to be a waste product of anaerobe glycolytic activity, lactate is now recognized as an energy source in skeletal muscles. While lactate metabolism has been extensively studied in vivo, underlying cellular processes are poorly described. This study aimed to examine lactate metabolism in cultured human myotubes and to investigate effects of lactate exposure on metabolism of oleic acid and glucose. Lactic acid, fatty acid and glucose metabolism were studied in myotubes using [14C(U)]lactic acid, [14C]oleic acid and [14C(U)]glucose, respectively. Myotubes expressed both the MCT1, MCT2, MCT3 and MCT4 lactate transporters, and lactic acid was found to be a substrate for both glycogen synthesis and lipid storage. Pyruvate and palmitic acid inhibited lactic acid oxidation, whilst glucose and α-cyano-4-hydroxycinnamic acid inhibited lactic acid uptake. Acute addition of lactic acid inhibited glucose and oleic acid oxidation, whereas oleic acid uptake was increased. Pretreatment with lactic acid for 24 h did not affect glucose or oleic acid metabolism. By replacing glucose with lactic acid during the whole culturing period, glucose uptake and oxidation were increased by 2.8-fold and 3-fold, respectively, and oleic acid oxidation was increased 1.4-fold. Thus, lactic acid has an important role in energy metabolism of human myotubes.

Arteriovenous blood metabolomics: An efficient method to determine the key metabolic pathway for milk synthesis in the intra-mammary gland

The present study aimed to identify metabolic signature changes of the arteriovenous metabolome and the new metabolites that involved in mammary biological process during milk synthesis. GC/MS-based metabolomics profiling of arteriovenous plasma from 30 lactating dairy cows fed three diets identified a total of 144 metabolites. Phenylalanine and tyrosine, involved in aminoacyl-tRNA biosynthesis and phenylalanine metabolism, were shown higher expression in the artery than in the vein based on both GC/MS and targeted analysis for cows fed both alfalfa hay diet and rice straw diet. Mammary uptake or clearance of citric acid, stearic acid, oleic acid, fructose, β-mannosylglycerate, 4-hydroxybutyrate, and D-talose were significantly correlated with milk performance or feed intake, indicating that these metabolites might be newly identified precursors or indicators of milk synthesis. This comprehensive assessment of metabolic changes in the arteriovenous metabolome will provide a fundamental understanding of the key metabolites involved in milk synthesis and shows implications of how metabolites from arteriovenous plasma across MG are involved in biological processes or physiological functions for milk synthesis. The newly identified metabolites from the present study provide potential new targeted insights into the study of physiological process for milk synthesis in the MG.

Cathepsin B regulates hepatic lipid metabolism by cleaving liver fatty acid–binding protein

Synthesis and secretion of hepatic triglycerides (TAG) associated with very-low-density lipoprotein (VLDL) play a major role in maintaining overall lipid homeostasis. This study aims to identify factors affecting synthesis and secretion of VLDL-TAG using the growth hormone-deficient Ames dwarf mouse model, which has reduced serum TAG. Proteomic analysis coupled with a bioinformatics-driven approach revealed that these mice express greater amounts of hepatic cathepsin B and lower amounts of liver fatty acid-binding protein (LFABP) than their wildtype littermates. siRNA-mediated knockdown of cathepsin B in McA-RH7777 cells resulted in a 39% increase in [3H]TAG associated with VLDL secretion. Cathepsin B knockdown was accompanied by a 74% increase in cellular LFABP protein levels, but only when cells were exposed to 0.4 mm oleic acid (OA) complexed to BSA. The cathepsin B knockdown and 24-h treatment with OA resulted in increased CD36 expression alone and additively. Co-localization of LFABP and cathepsin B was observed in a distinct Golgi apparatus-like pattern, which required a 1-h OA treatment. Moreover, we observed co-localization of LFABP and apoB, independent of the OA treatment. Overexpression of cathepsin B resulted in decreased OA uptake and VLDL secretion. Co-expression of cathepsin B and cathepsin B-resistant mutant LFABP in McA-RH7777 cells resulted in an increased TAG secretion as compared with cells co-expressing cathepsin B and wildtype LFABP. Together, these data indicate that cathepsin B regulates VLDL secretion and free fatty acid uptake via cleavage of LFABP, which occurs in response to oleic acid exposure.

Thermoexfoliated and hydrophobized vermiculites for oleic acid removal

The aim of the present study was to investigate the removal efficiency of oleic acid from aqueous solutions by thermally expanded and hydrophobized vermiculites. The expansion of the samples was carried out in a furnace at 1000°C for 2min. The hydrophobization using polymethyl-hydro-siloxane as hydrophobing derivatizing reagent was performed by immersion and hydrophobizing atmosphere methods. The investigation was started with two vermiculites from Brazil, the Goiás and Piauí states, respectively. After some previous tests the Goiás vermiculite was selected to investigate five effects: 1) Adsorption at different pH. 2) Adsorption at different concentrations of hydrophobizing reactive and different weights of vermiculite. 3) Adsorbent mass. 4) Influence of the number of stages of adsorption. 5) Influence of salinity. Oleic acid uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) models. In addition, the adsorption equilibrium was described well by the DKR isotherm model, indicative of a cooperative process. The maximum adsorption capacity obtained with DKR model was of 1.29mol/g of oleic acid. The hydrophobization Goiás vermiculite and the adsorption of oleic acid were verified using infrared spectroscopy. The findings of this study showed that this thermally expanded and hydrophobized vermiculite: 1) was very suitable for the recovery of oleic acid in water; 2) the adsorption increased with the increase of the salinity of the aqueous medium; 3) it was possible to reuse vermiculite unsaturated to recover more oleic acid.