Palmitate Concentrations Research Articles

Molecular Analysis of Mutant Alleles for Elevated Palmitate Concentration in Soybean

ABSTRACTSoybean [Glycine max (L.) Merr.] oil with increased palmitate concentration may be useful for some food and industrial applications. Chemical mutagenesis was used to develop mutant alleles for elevated palmitate concentration that were designated as fap2(A21), fap4(A24), fap5(A27), fap6(A25), and fap7(A30) based on classical genetic analysis. The objective of our study was to determine whether the elevated palmitate phenotypes in any of these lines were associated with mutations in either of the two known 3‐ketoacyl‐ACP synthase II (KAS II) genes of soybean, GmKAS IIA and GmKAS IIB. Deoxyribonucleic acid sequence analysis revealed single nucleotide polymorphisms (SNPs) that differentiated mutant and wild‐type alleles in one of the GmKAS genes in lines A21, A25, A27, and A30 but not in A24. The identified SNPs resulted in nonconservative amino acid substitutions that were predicted to impair enzyme function. The fap2(A21) allele was associated with two consecutive SNPs within the GmKAS IIA gene, confirming its allelic relationship to fap2(C1727) that was known to have a mutant SNP within the same gene. The allele designated fap5(A27) also had a SNP within the GmKAS IIA gene, indicating that its designation should be changed to fap2(A27). The fap6(A25) and fap7(A30) alleles each contained a single SNP at different locations within the GmKAS IIB gene. We propose that the designation of the mutant allele in A25 remain fap6(A25) and that the allele in A30 be changed from fap7(A30) to fap6(A30).

Elevated Palmitate and Stearate Concentrations in the Oil of Low‐Phytate Soybean Lines

Crop Science 51:1997-2004 (2011) In Volume 51, Number 5, Table of Contents, the above-mentioned article was incorrectly listed as a “Note.” The article should have been listed as an “Original Research” article under the “Crop Breeding and Genetics” heading.

Effect of the Simultaneous Interaction among Ascorbic Acid, Iron and pH on the Oxidative Stability of Oil-in-Water Emulsions

The objective of this study was to demonstrate how different factors can simultaneously influence the oxidative stability of an oil-in-water emulsion, and how these factors can be used to enlarge the variation range of oxidation markers, expressed as peroxide value (PV) and TBARS. Initially, a Plackett-Burman design was used to screen seven factors (temperature, pH, and iron, copper, ascorbyl palmitate, ascorbic acid, and sodium chloride concentrations). A temperature elevation of 30 to 60 °C reduced PV and TBARS, a pH change from 3.0 to 7.0 increased PV and reduced TBARS, and the presence of ascorbic acid (1 mmol/L) had no significant effect on PV but increased TBARS (p < 0.05). Thus, the temperature was fixed at 30 °C, and an emulsion was formulated with different combinations of ascorbic acid, iron, and pH according to a central composite rotatable design. Regression models were fitted to PV and TBARs responses and optimized to get the higher values of both markers of oxidation. The optimized emulsion contained 1.70 mmol/L AH (ascorbic acid) and 0.885 mmol/L FeSO(4) · 7H(2)O (1.0 mmol/L Fe(2+)) at pH 5.51 and 30 °C. The range of variation observed for oxidation markers in the optimized emulsion model (PV, 0-4.27 mequiv/L; TBARS, 0-13.55 mmol/L) was larger than the variation observed in the nonoptimized model (PV, 0-1.05 mequiv/L; TBARS, 0-1.00 mmol/L). The antioxidant activity of six compounds (Trolox, α-tocopherol, caffeic acid, gallic acid, catechin, and TBHQ) was evaluated using the optimized emulsion conditions. After application of the Tukey HSD post hoc statistical test, the samples that were not different (p < 0.05) in the nonoptimized emulsions showed a significant difference in the optimized emulsions. Considering the importance of the interactions on oxidation studies, our model represents a significant improvement in a direct methodology that can be applied to evaluate natural compounds under different combination of factors.

An 11-bp Insertion in Zea mays fatb Reduces the Palmitic Acid Content of Fatty Acids in Maize Grain

The ratio of saturated to unsaturated fatty acids in maize kernels strongly impacts human and livestock health, but is a complex trait that is difficult to select based on phenotype. Map-based cloning of quantitative trait loci (QTL) is a powerful but time-consuming method for the dissection of complex traits. Here, we combine linkage and association analyses to fine map QTL-Pal9, a QTL influencing levels of palmitic acid, an important class of saturated fatty acid. QTL-Pal9 was mapped to a 90-kb region, in which we identified a candidate gene, Zea mays fatb (Zmfatb), which encodes acyl-ACP thioesterase. An 11-bp insertion in the last exon of Zmfatb decreases palmitic acid content and concentration, leading to an optimization of the ratio of saturated to unsaturated fatty acids while having no effect on total oil content. We used three-dimensional structure analysis to explain the functional mechanism of the ZmFATB protein and confirmed the proposed model in vitro and in vivo. We measured the genetic effect of the functional site in 15 different genetic backgrounds and found a maximum change of 4.57 mg/g palmitic acid content, which accounts for ∼20–60% of the variation in the ratio of saturated to unsaturated fatty acids. A PCR-based marker for QTL-Pal9 was developed for marker-assisted selection of nutritionally healthier maize lines. The method presented here provides a new, efficient way to clone QTL, and the cloned palmitic acid QTL sheds lights on the genetic mechanism of oil biosynthesis and targeted maize molecular breeding.

Lípidos sanguíneos en cerdos alimentados con pijiguao (Bactris gasipaes Kunth) y lisina sintética

RESUMENObjetivo. Evaluar el efecto de la harina de pijiguao y lisina sintética sobre los lípidossanguíneos de cerdos en crecimiento y engorde. Materiales y métodos. El estudio serealizó en dos etapas. En la primera etapa se utilizaron 72 cerdos castrados en crecimientode 30 ± 0.5 kg, en un arreglo factorial 2x3: dos niveles de lisina sintética (0 y 2.70 g/kg)y tres niveles de harina de pijiguao (0, 160 y 320 g/kg). En la segunda etapa se utilizaron16 cerdos en engorde de 67.25 ± 1.17 kg, en un arreglo factorial 2x2: dos niveles de lisinasintética (0 y 2.70 g/kg) y dos niveles de pijiguao (0 y 175 g/kg). Se determinaron lasconcentraciones séricas de triacilgliceroles, colesterol total y ácidos grasos. Resultados.Los cerdos en crecimiento que consumieron pijiguao presentaron menores (p&lt;0.001)concentraciones de colesterol que el grupo control (2.27 y 2.23 mmol/l vs 2.56 mmol/l) ytriacilgliceroles (0.34 y 0.28 mmol/l vs 0.42 mmol/l). El ácido oleico incrementó (p&lt;0.01)con el mayor nivel de pijiguao (20.78% a 28.84%), y la lisina aumentó (p&lt;0.05) el ácidolinoleico (27.83% a 31.29%). Los cerdos alimentados con pijiguao y lisina mostraronmenor (p&lt;0.001) ácido palmítico que el grupo con pijiguao sin lisina (0.23 y 0.19% vs0.45 y 0.62%, respectivamente). En la etapa de engorde los triacilgliceroles disminuyeron(p&lt;0.05) en los cerdos alimentados con pijiguao y lisina (0.46 a 0.36 mmol/l). Los cerdosalimentados con pijiguao mostraron menor ácido linoleico y mayor ácido oleico (p&lt;0.001).Conclusiones. Las dietas con pijiguao y lisina sintética no causaron efectos negativossobre los lípidos sanguíneos de cerdos.

Elevated Palmitate and Stearate Concentrations in the Oil of Low‐Phytate Soybean Lines

The combination of low phytate (LP) and low saturated fatty esters in a soybean [Glycine max (L.) Merr.] cultivar could improve the availability of inorganic phosphorus (Pi) in livestock rations and improve the nutrition of the oil used in human diets. Previous studies indicated that lines with the lpa1 and lpa2 alleles for LP and the fap1(C1726) and fap3(A22) alleles for reduced palmitate had greater palmitate plus stearate (saturate) concentrations than normal‐phytate (NP) lines. The objective of our study was to evaluate possible causes of the association between LP and saturate concentration. Low‐phytate and NP F3 individuals and their progeny were evaluated from three single‐cross populations segregating for Lpa1, lpa1, Lpa2, and lpa2 and homozygous for fap1(C1726) and fap3(A22). The mean palmitate, stearate, and saturate concentrations of the LP lines were significantly greater than the NP lines in all the populations. The frequency of F3:4 lines with a saturate concentration of ≤70 g kg−1 averaged across populations was 8% for the LP lines and 74% for the NP lines. The elevated saturates was not attributable to genetic factors linked to lpa1 or lpa2 but was associated with a greater concentration of Pi in LP individuals. The apparent relationship between elevated Pi and elevated saturate concentrations would hinder the development of LP cultivars with low saturated fatty esters.

Storage of Circulating Free Fatty Acid in Adipose Tissue of Postabsorptive Humans

OBJECTIVEPreferential upper-body fat gain, a typical male pattern, is associated with a greater cardiometabolic risk. Regional differences in lipolysis and meal fat storage cannot explain sex differences in body fat distribution. We examined the potential role of the novel free fatty acid (FFA) storage pathway in determining body fat distribution in postabsorptive humans and whether adipocyte lipogenic proteins (CD36, acyl-CoA synthetases, and diacylglycerol acyltransferase) predict differences in FFA storage.RESEARCH DESIGN AND METHODSRates of postabsorptive FFA (palmitate) storage into upper-body subcutaneous (UBSQ) and lower-body subcutaneous (LBSQ) fat were measured in 28 men and 53 premenopausal women. Stable and radiolabeled palmitate tracers were intravenously infused followed by subcutaneous fat biopsies. Body composition was assessed with a combination of dual-energy X-ray absorptiometry and computed tomography.RESULTSWomen had greater FFA (palmitate) storage than men in both UBSQ (0.37 ± 0.15 vs. 0.27 ± 0.18 μmol · kg−1 · min−1, P = 0.0001) and LBSQ (0.42 ± 0.19 vs. 0.22 ± 0.11 μmol · kg−1 · min−1, P < 0.0001) fat. Palmitate storage rates were significantly greater in LBSQ than UBSQ fat in women, whereas the opposite was true in men. Plasma palmitate concentration positively predicted palmitate storage in both depots and sexes. Adipocyte CD36 content predicted UBSQ palmitate storage and sex-predicted storage in LBSQ fat. Palmitate storage rates per kilogram fat did not decrease as a function of fat mass, whereas lipolysis did.CONCLUSIONSThe FFA storage pathway, which had remained undetected in postabsorptive humans until recently, can have considerable, long-term, and sex-specific effects on body fat distribution. It can also offer a way of protecting the body from excessive circulating FFA in obesity.

Molecular Characterization of the Mutant fap3(A22) Allele for Reduced Palmitate Concentration in Soybean

ABSTRACTReduction of the palmitate concentration in soybean [Glycine max (L.) Merr.] oil is desirable for reducing the amount of saturated fat in the human diet. Chemical mutagenesis was used to develop the line A22 with the mutant allele designated fap3(A22) that reduces palmitate concentration in the seed oil. The objective of our study was to determine the molecular basis of the fap3(A22) mutation and develop a corresponding molecular marker to assist in future efforts for developing soybean cultivars with low saturated fat. DNA sequence analysis of the GmFATB1a gene of soybean revealed a single nucleotide polymorphism (SNP) resulting in a nonconservative amino acid substitution that was likely to be detrimental to the function of the 16:0–acyl carrier protein (ACP) thioesterase (TE) enzyme. An association analysis was conducted using F2–derived lines from a cross between the cultivar Archer (Fap3Fap3) and A22 (fap3fap3) that had been analyzed for their palmitate concentration by gas chromatography. Molecular genotyping of these lines established a perfect correlation between lines phenotypically classified as homozygous for the Fap3 allele or homozygous for the fap3(A22) allele based on their palmitate concentration. The polymorphism in the GmFATB1a gene was used to develop a functional, codominant marker that could be used to distinguish the Fap3 and fap3(A22) alleles in segregating populations. This marker will be useful for breeders who are developing low‐saturate cultivars with the fap3(A22) allele.

Prolonged QT interval and lipid alterations beyond β-oxidation in very long-chain acyl-CoA dehydrogenase null mouse hearts

Patients with very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency frequently present cardiomyopathy and heartbeat disorders. However, the underlying factors, which may be of cardiac or extra cardiac origins, remain to be elucidated. In this study, we tested for metabolic and functional alterations in the heart from 3- and 7-mo-old VLCAD null mice and their littermate counterparts, using validated experimental paradigms, namely, 1) ex vivo perfusion in working mode, with concomitant evaluation of myocardial contractility and metabolic fluxes using (13)C-labeled substrates under various conditions; as well as 2) in vivo targeted lipidomics, gene expression analysis as well as electrocardiogram monitoring by telemetry in mice fed various diets. Unexpectedly, when perfused ex vivo, working VLCAD null mouse hearts maintained values similar to those of the controls for functional parameters and for the contribution of exogenous palmitate to β-oxidation (energy production), even at high palmitate concentration (1 mM) and increased energy demand (with 1 μM epinephrine) or after fasting. However, in vivo, these hearts displayed a prolonged rate-corrected QT (QTc) interval under all conditions examined, as well as the following lipid alterations: 1) age- and condition-dependent accumulation of triglycerides, and 2) 20% lower docosahexaenoic acid (an omega-3 polyunsaturated fatty acid) in membrane phospholipids. The latter was independent of liver but affected by feeding a diet enriched in saturated fat (exacerbated) or fish oil (attenuated). Our finding of a longer QTc interval in VLCAD null mice appears to be most relevant given that such condition increases the risk of sudden cardiac death.

Fruit and vegetable intakes in relation to plasma nutrient concentrations in women in Shanghai, China

To evaluate the validity of fruit and vegetable intakes as it relates to plasma carotenoid and vitamin C concentrations in Chinese women, using three classification schemes. Intakes were calculated using an interviewer-administered FFQ. Fruits and vegetables, botanical groups and high-nutrient groups were evaluated. These three classification schemes were compared with plasma carotenoid and vitamin C concentrations from blood samples collected within 1 week of questionnaire completion. Shanghai, China. Participants (n 2031) comprised women who had participated in a case-control study of diet and breast-related diseases nested within a randomized trial of breast self-examination among textile workers (n 266 064) Fruit intake was significantly (P < 0·05) and positively associated with plasma concentrations of α-tocopherol, β-cryptoxanthin, lycopene, α-carotene, β-carotene, retinyl palmitate and vitamin C. Fruit intake was inversely associated with γ-tocopherol and lutein + zeaxanthin concentrations. Vegetable consumption was significantly and positively associated with γ-tocopherol and β-cryptoxanthin concentrations. Each botanical and high-nutrient group was also significantly associated with particular plasma nutrient concentrations. Fruit and vegetable intakes and most plasma nutrient concentrations were significantly associated with season of interview. These results suggest that the manner in which fruits and vegetables are grouped leads to different plasma nutrient exposure information, which may be an important consideration when testing and generating hypotheses regarding disease risk in relation to diet. Interview season should be considered when evaluating the associations of reported intake and plasma nutrients with disease outcomes.

Effects of nonenzymatic glycation and fatty acids on functional properties of human albumin

Human serum albumin nonenzymatically condenses with glucose to form stable Amadori adducts that are increased with the hyperglycemia of diabetes. The present study evaluated the influence of fatty acids, which are major endogenous ligands, on albumin glycation and of glycation on albumin conformation and exogenous ligand binding. Physiologic concentrations of palmitate, oleate, and linoleate reduced the ability of albumin to form glucose adducts, whereas glycation decreased intrinsic fluorescence, lowered the affinity for dansylsarcosine, and diminished the fatty acid–induced increase in limiting fluorescence of protein-bound warfarin that was observed with nonglycated albumin. The findings indicate that fatty acids impede the ability of albumin to undergo Amadori glucose modification and induce conformational changes affecting exogenous ligand binding, and that nonenzymatic glycation of albumin induces alterations in structural and functional properties that may have import in lipid transport and atherogenesis.

Impact of the MON89788 Event for Glyphosate Tolerance on Agronomic and Seed Traits of Soybean

ABSTRACTGlyphosate [N‐(phosphonomethyl)glycine] is a popular herbicide for weed control in fields planted to soybean [Glycine max (L.) Merr.] cultivars with a transgene that provides tolerance to the chemical. A transgenic event MON89788, known commercially as Roundup Ready 2 Yield (Monsanto Co., St. Louis, MO), was developed by the Monsanto Co. as an alternative to the event 40–3–2 for glyphosate tolerance in soybean. The objective of our study was to compare the agronomic and seed traits of glyphosate‐tolerant (GT) lines and glyphosate‐susceptible (GS) lines from populations segregating for MON89788. The transgene was backcrossed into three GS cultivars to develop BC2 populations. There were 27 GT and 27 GS BC2F2–derived lines from each backcross population evaluated at four Iowa environments in 2010. The means of the GT lines were not significantly different from the GS lines in any of the populations for seed yield, lodging score, and palmitate, oleate, and linoleate concentrations. The maximum significant difference between the means of the two types was 0.4 d for maturity date, 2 cm for plant height, 5 mg sd−1 for seed weight, and 2 g kg−1 for protein, 1 g kg−1 for oil, 1 g kg−1 for stearate, and 0.2 g kg−1 for linolenate concentrations. The significant differences among lines within each type and the overlap in their distributions for all of the traits indicated that it would be possible to select GT or GS lines with comparable performance from populations developed by crossing a GS parent to a GT parent with the MON89788 event.

Free fatty acids as inducers and regulators of uncoupling of oxidative phosphorylation in liver mitochondria with participation of ADP/ATP- and aspartate/glutamate-antiporter

In liver mitochondria fatty acids act as protonophoric uncouplers mainly with participation of internal membrane protein carriers - ADP/ATP and aspartate/glutamate antiporters. In this study the values of recoupling effects of carboxyatractylate and glutamate (or aspartate) were used to assess the degree of participation of ADP/ATP and aspartate/glutamate antiporters in uncoupling activity of fatty acids. These values were determined from the ability of these recoupling agents to suppress the respiration stimulated by fatty acids and to raise the membrane potential reduced by fatty acids. Increase in palmitic and lauric acid concentration was shown to increase the degree of participation of ADP/ATP antiporter and to decrease the degree of participation of aspartate/glutamate antiporter in uncoupling to the same extent. These data suggest that fatty acids are not only inducers of uncoupling of oxidative phosphorylation, but that they also act the regulators of this process. The linear dependence of carboxyatractylate and glutamate recoupling effects ratio on palmitic and lauric acids concentration was established. Comparison of the effects of fatty acids (palmitic, myristic, lauric, capric, and caprylic having 16, 14, 12, 10, and 8 carbon atoms, respectively) has shown that, as the hydrophobicity of fatty acids decreases, the effectiveness decreases to a greater degree than the respective values of their specific uncoupling activity. The action of fatty acids as regulators of uncoupling is supposed to consist of activation of transport of their anions from the internal to the external monolayer of the internal membrane with participation of ADP/ATP antiporter and, at the same time, in inhibition of this process with the participation of aspartate/glutamate antiporter.

Palmitoylation Controls Dopamine Transporter Kinetics, Degradation, and Protein Kinase C-dependent Regulation

Palmitoylation is a lipid modification that confers diverse functions to target proteins and is a contributing factor for many neuronal diseases. In this study, we demonstrate using [(3)H]palmitic acid labeling and acyl-biotinyl exchange that native and expressed dopamine transporters (DATs) are palmitoylated, and using the palmitoyl acyltransferase inhibitor 2-bromopalmitate (2BP), we identify several associated functions. Treatment of rat striatal synaptosomes with 2BP using lower doses or shorter times caused robust inhibition of transport V(max) that occurred with no losses of DAT protein or changes in DAT surface levels, indicating that acute loss of palmitoylation leads to reduction of transport kinetics. Treatment of synaptosomes or cells with 2BP using higher doses or longer times resulted in DAT protein losses and production of transporter fragments, implicating palmitoylation in regulation of transporter degradation. Site-directed mutagenesis indicated that palmitoylation of rat DAT occurs at Cys-580 at the intracellular end of transmembrane domain 12 and at one or more additional unidentified site(s). Cys-580 mutation also led to production of transporter degradation fragments and to increased phorbol ester-induced down-regulation, further supporting palmitoylation in opposing DAT turnover and in opposing protein kinase C-mediated regulation. These results identify S-palmitoylation as a major regulator of DAT properties that could significantly impact acute and long term dopamine transport capacity.

The Effects of Glyburide on Apoptosis and Endoplasmic Reticulum Stress in INS-1 Cells in a Glucolipotoxic Condition

Backgroundβ-cell death due to endoplasmic reticulum (ER) stress has been regarded as an important pathogenic component of type 2 diabetes. The possibility has been suggested that sulfonylurea, currently being used as one of the main oral hypoglycemic agents of type 2 diabetes, increases ER stress, which could lead to sulfonylurea failure. The authors of the present study examined ER stress of β-cells in a glucolipotoxic condition using glyburide (GB) in an environment mimicking type 2 diabetes.MethodsApoptosis was induced by adding various concentrations of GB (0.001 to 200 µM) to a glucolipotoxic condition using 33 mM glucose, and the effects of varied concentrations of palmitate were evaluated via annexin V staining. The markers of ER stress and pro-apoptotic markers were assessed by Western blotting and semi-quantitative reverse transcription-polymerase chain reaction. Additionally, the anti-apoptotic markers were evaluated.ResultsAddition of any concentration of GB in 150 µM palmitate and 33 mM glucose did not increase apoptosis. The expression of phosphorylated eukaryotic initiation factor (eIF-2α) was increased and cleaved caspase 3 was decreased by adding GB to a glucolipotoxic condition. However, other ER stress-associated markers such as Bip-1, X-box binding protein-1, ATF-4 and C/EBP-homologous protein transcription factor and anti-apoptotic markers phosphor-p85 phosphatidylinositol 3-kinase and phosphorylation of Akt did not change significantly.ConclusionGB did not show further deleterious effects on the degree of apoptosis or ER stress of INS-1 cells in a glucolipotoxic condition. Increased phosphorylation of eIF-2α may attenuate ER stress for adaptation to increased ER protein load.

Abnormal metabolism flexibility in response to high palmitate concentrations in myotubes derived from obese type 2 diabetic patients

Insulin resistance in type 2 diabetes (T2D) is associated with intramuscular lipid (IMCL) accumulation. To determine whether impaired lipid oxidation is involved in IMCL accumulation, we measured expression of genes involved in mitochondrial oxidative metabolism or biogenesis, mitochondrial content and palmitate beta-oxidation before and after palmitate overload (600μM for 16h), in myotubes derived from healthy subjects and obese T2D patients. Mitochondrial gene expression, content and network were not different between groups. Basal palmitate beta-oxidation was not affected in T2D myotubes, whereas after 16h of palmitate pre-treatment, T2D myotubes in contrast to control myotubes, showed an inability to increase palmitate beta-oxidation (p<0.05). Interestingly, acetyl-CoA carboxylase (ACC) phosphorylation was increased with a tendency for statistical significance after palmitate pre-treatment in control myotubes (p=0.06) but not in T2D myotubes which can explain their inability to increase palmitate beta-oxidation after palmitate overload. To determine whether the activation of the AMP activated protein kinase (AMPK)-ACC pathway was able to decrease lipid content in T2D myotubes, cells were treated with AICAR and metformin. These AMPK activators had no effect on ACC and AMPK phosphorylation in T2D myotubes as well as on lipid content, whereas AICAR, but not metformin, increased AMPK phosphorylation in control myotubes. Interestingly, metformin treatment and mitochondrial inhibition by antimycin induced increased lipid content in control myotubes. We conclude that T2D myotubes display an impaired capacity to respond to metabolic stimuli.

Translationally controlled tumour protein (TCTP) is a novel glucose-regulated protein that is important for survival of pancreatic beta cells.

This study used proteomics and biochemical approaches to identify novel glucose-regulated proteins and to unveil their role in pancreatic beta cell function. Translationally controlled tumour protein (TCTP) was identified to be one such protein, and further investigations into its function and regulation were carried out. Global protein profiling of beta cell homogenates following glucose stimulation was performed using two-dimensional gel electrophoresis. Proteins were identified by mass spectroscopy analysis. Immunoblotting was used to investigate alterations in TCTP protein levels in response to glucose stimulation or cell stress induced by palmitate. To investigate the biological function of TCTP, immunolocalisation, gene knockdown and overexpression of Tctp (also known as Tpt1) were performed. Apoptosis was measured in Tctp knockdown or Tctp-overexpressing cells. Glucose-stimulated insulin secretion was carried out in Tctp knockdown cells. TCTP was identified as a novel glucose-regulated protein, the level of which is increased at stimulatory glucose concentration. Glucose also induced TCTP dephosphorylation and its partial translocation to the mitochondria and the nucleus. TCTP protein levels were downregulated in response to cell stress induced by palmitate or thapsigargin treatments. Gene knockdown by small interfering RNA led to increased apoptosis, whereas overproduction of TCTP prevented palmitate-induced cell death. Regulation of TCTP protein levels by glucose is likely to be an important cyto-protective mechanism for pancreatic beta cells against damage caused by hyperglycaemia. In contrast, high concentration of palmitate causes cell stress, reduction in TCTP levels and consequently reduced cell viability. Our results imply that TCTP levels influence the sensitivity of beta cells to apoptosis.

Different effects of oleate vs. palmitate on mitochondrial function, apoptosis, and insulin signaling in L6 skeletal muscle cells: role of oxidative stress.

The type of free fatty acids (FFAs), saturated or unsaturated, is critical in the development of insulin resistance (IR), since the degree of saturation correlates with IR. We compared the effects of the saturated FFA palmitate, the unsaturated FFA oleate, and a mixture of each on the production of mitochondrial reactive oxygen species (mtROS), mitochondrial DNA (mtDNA) damage, mitochondrial function, apoptosis, and insulin-signaling pathway in skeletal muscle cells. Only palmitate caused a significant increase of mtROS production, which correlated with concomitant mtDNA damage, mitochondrial dysfunction, induction of JNK, apoptosis, and inhibition of insulin signaling. Blocking de novo synthesis of ceramide abolished the effects of palmitate on mtROS production, viability, and insulin signaling. Oleate alone did not cause mtROS generation and mtDNA damage, and its addition to palmitate prevented palmitate-induced mtDNA damage, increased total ATP levels and cell viability, and prevented palmitate-induced apoptosis and inhibition of insulin-stimulated Akt (Ser(473)) phosphorylation. The peroxisome proliferator activator receptor-γ coactivator 1α (PGC-1α) protein level and promoter activity were decreased at concentrations of palmitate ≥0.5 mM, whereas addition of oleate increased both PGC-1α level and promoter activity. Expression of the mitochondrial transcription factor (TFAM) was significantly diminished after palmitate but not oleate treatment. Addition of the ROS scavenger, N-acetylcystein (NAC), to palmitate restored both the expression and promoter activity of PGC-1α as well as TFAM expression. We propose that 1) mtROS generation is the initial event in the induction of mitochondrial dysfunction and consequent apoptosis and the inhibition of insulin signaling and that 2) oleate ameliorates palmitate-induced mitochondrial dysfunction and thus may contribute to the prevention of palmitate-induced IR.

Activation of PPARδ promotes mitochondrial energy metabolism and decreases basal insulin secretion in palmitate-treated β-cells

The peroxisome proliferator-activated receptor δ (PPARδ) regulates the expression of genes involved in cellular lipid and cell energy metabolism in many metabolically active tissues, such as liver, muscle, and fat, and plays a role in the cellular response to stress and environmental stimuli. The particular role of PPARδ in insulin-secreting β-cells, however, is not well understood; we recently identified the cell-specific role of PPARδ on mitochondrial energy metabolism and insulin secretion in lipotoxic β-cells. After treatment of HIT-T15 cells, a syrian hamster pancreatic β-cell line, with high concentrations of palmitate and/or the specific PPARδ agonist GW501516, we detected the gene expression changes for transcripts, such as peroxisome proliferator-activated receptor gamma co-activator 1 (PGC-1α), nuclear respiratory factor 1 (NRF-1), mitochondrial transcription factor A (mtTFA), the protein levels of the mitochondria uncoupling protein 2 (UCP2), mitochondrial morphology, the insulin secretion capacity and ATP/ADP ratio. Our results show that GW501516 treatment promoted generation of mitochondrial ATP, as well as expression levels of PGC-1α, NRF-1 and mtTFA, decreased basal insulin secretion, but had no effect on glucose-stimulated insulin secretion (GSIS), increased amounts of UCP2 and changed ATP-to-ADP ratio, improved mitochondrial morphology in palmitate-treated β-cells. GW501516-induced activation of PPARδ enhanced mitochondrial energy metabolism, but also promoted a concomitant mitochondrial uncoupling and resulted in decreased basal insulin secretion and restricted GSIS; this observation indicated the possible action of a protective mechanism responding to the alleviation of excessive lipid load and basal insulin secretion in lipotoxic β-cells.

Effects of palmitic fatty acid on mechanical, thermal and permeability attributes of pistachio globulin edible film.

Novel edible emulsified films were made using pistachio globulin protein (PGP) and palmitic fatty acid at concentrations of 2, 4, and 6 % w/w protein by Tween-80 and homogenization technique. Addition of palmitic acid to the PGP filmogenic solution resulted in great reduction of WVP in the emulsified films (37-40 %). Concentration of palmitic acid did not create significant difference (P>0.05) among WVP of the emulsified films. The WVP decreased as function of palmitic acid concentration. Water solubility of PGP films was 44.8 % and slightly decreased in the emulsified films. Oxygen permeability of the emulsified films were lower than the PGP films, but the differences were not significant (P>0.05). Tensile strength and elongation at break of the emulsified films were diminished as a result of palmitic acid addition. Incorporation of palmitic acid led to produce the opaque films, which opacity increased as function of palmitic acid concentration. Glass transition temperature (Tg) was determined by differential scanning calorimetry. The Tg of the PGP film revealed at 127.19 °C and was not affected by palmitic acid. Keywords: Pistachio globulin protein, Palmitic acid, Gas permeability, Elongation, Tensile strength