stearoyl-CoA Desaturase mRNA Expression Research Articles

Identification of Key Proteomic Markers for Enhanced Conjugated Linoleic Acid Biosynthesis in Lactating Goats via Linseed Oil Supplementation.

This study investigated the effects of linseed oil (LO) supplementation on conjugated linoleic acid (CLA) biosynthesis in lactating Saanen goats. Goats (DIM = 96 ± 14 days) were divided into control (n = 6) and LO treatment (n = 6) groups. LO supplementation was implemented in both short- and long-term experimental settings. Short-term LO supplementation significantly increased trans-11 vaccenic acid and cis-9,trans-11 CLA in milk fat without affecting lactation performance. Using two-dimensional gel electrophoresis, we identified six upregulated proteins in milk somatic cells, including translocon-associated protein (SSRD), succinyl-CoA ligase (SUCB2), ATP synthase subunit (ATPD), stress-70 protein (GRP75), NADH dehydrogenase (NDUFS2), and cytochrome complex QCR1. Long-term LO supplementation enhanced milk fat content and cis-9,trans-11 CLA levels, while significantly elevating the mRNA expression of stearoyl-CoA desaturase (SCD) and all previously identified proteins-including proteasome 20s subunit alpha 5 (PSMA5). These findings extend beyond the known SCD pathway, revealing novel protein markers and potential mechanisms associated with CLA biosynthesis in mammary tissue and milk somatic cells.

Biological effects related to exposure to polychlorinated biphenyl (PCB) and decabromodiphenyl ether (BDE-209) on cats.

As an animal familiar to humans, cats are considered to be sensitive to chemicals; cats may be exposed to polychlorinated biphenyls (PCBs) and decabromodiphenyl ether (BDE-209) from indoor dust, household products, and common pet food, leading to adverse endocrine effects, such as thyroid hormone dysfunction. To elucidate the general biological effects resulting from exposure of cats to PCBs and PBDEs, cats were treated with a single i.p. dose of a principal mixture of 12 PCBs and observed for a short-term period. Results revealed that the testis weight, serum albumin, and total protein of the treated group decrease statistically in comparison with those in the control group. The negative correlations suggested that the decrease in the total protein and albumin levels may be disturbed by 4'OH-CB18, 3'OH-CB28 and 3OH-CB101. Meanwhile, the serum albumin level and relative brain weight decreased significantly for cats subjected to 1-year continuous oral administration of BDE-209 in comparison to those of control cats. In addition, the subcutaneous fat as well as serum high-density lipoprotein (HDL) and triglycerides (TG) levels increased in cats treated with BDE-209 and down-regulation of stearoyl-CoA desaturase mRNA expression in the liver occurred. These results suggested that chronic BDE-209 treatment may restrain lipolysis in the liver, which is associated with lipogenesis in the subcutaneous fat. Evidence of liver and kidney cell damage was not observed as there was no significant difference in the liver enzymes, blood urea nitrogen and creatinine levels between the two groups of both experiments. To the best of our knowledge, this is the first study that provides information on the biochemical effects of organohalogen compounds in cats. Further investigations on risk assessment and other potential health effects of PCBs and PBDEs on the reproductive system, brain, and lipid metabolism in cats are required.

Multiomics Analysis of IMiD/CELMoD Resistant Multiple Myeloma Models Uncovers Novel and Targetable Vulnerabilities in the SREBP Lipid Synthesis Pathway

Background Acquired resistance to immunomodulatory drugs (IMiDs)/cereblon (CRBN) E3 ligase modulators (CELMoDs) is a major challenge in multiple myeloma (MM) treatment. These drugs bind to the CRBN component of the CRL4CRBN E3 ubiquitin ligase and designate a new set of substrates for degradation via the proteasome. Generation of resistance is frequently associated with decreased CRBN expression and this is due to genetic alteration in ~1/3rd of patients. Alternative drivers of the low CRBN state, and other mechanisms of resistance, need to be elucidated. To tackle this complex problem, MM models with acquired IMiD/CELMoD resistance were generated and multiomics analysis performed. Methods IMiD/CELMoD resistant human MM cell lines were generated by treating MM1s and H929 cells with lenalidomide (Len), pomalidomide (Pom) or iberdomide (Iber) at ~10x GI50 concentration for ~12 weeks until resistance was achieved. Resistant cell lines and controls were characterised by whole exome sequencing (WES), RNA-Seq and proteomics. A genome-wide loss-of-function CRISPR screen (Brunello library) was carried out in Iber-resistant MM1s; gene effect scores were calculated with the Chronos model and compared to parental MM1s using data from the Broad Institute DepMap portal. Pathway analysis was performed using g:Profiler. The Membrane Bound Transcription Factor Peptidase, Site 1 (MBTPS1) inhibitor PF-429242 was used to inhibit activation of the Sterol Regulatory-Element Binding Protein (SREBP) pathway and the effect on cell viability measured using CellTiter-Blue®. The Multiple Myeloma Research Foundation CoMMpass database was used to explore the correlation between mRNA expression of SREBP pathway genes in newly diagnosed patients and progression-free survival (PFS). Results All models were resistant to the IMiD/CELMoD with which they were generated (to 20-100x the GI50 concentration) and exhibited cross-resistance to other IMiDs/CELMoDs. Functional assays showed that well-characterised effects of IMiD/CELMoD treatment, e.g. degradation of Ikaros/Aiolos, were abrogated. WES showed Pom-resistant MM1S and Pom- and Iber-resistant H929 cells had acquired mutations in CRBN predicted to have a high impact on function. Len-resistant H929 cells had new copy number loss at the CRBN locus but Len- and Iber-resistant MM1s cells had no genetic changes in CRBN. CRBN protein expression was reduced in all resistant lines compared to control (log2 fold changes (FCs) by proteomics ranging from -0.25 to -1.95, adj p <0.05). Together these models display diverse resistance mechanisms, reflecting the clinical picture. Proteomic analysis of the resistant lines identified key changes in the SREBP pathway. The proteomes of the resistant lines were heterogeneous and the only pathway with common significant enrichment was SREBP/fatty acid metabolism (on analysis performed per cell line of proteins with significantly decreased expression). Stearoyl-CoA Desaturase (SCD), a key effector of the SREBP pathway, was one of only 5 proteins with significantly altered expression in all 6 cell lines compared to control. SCD had log2FCs ranging from -0.37 to -1.50 (adj p <0.05). Other key pathway members are shown in Figure 1. A genome-wide CRISPR screen using Iber-resistant MM1s cells identified potential new dependencies (gene effect score <-1 in resistant cells and >-0.5 in parental cells) in 47 genes including SCD and MBTPS1. MBTPS1 is critical for activation of the SREBP pathway and demonstrated one of the largest changes in gene effect (-1.4 vs -0.3). The activity of PF-429242, an inhibitor of MBTPS1, was explored in the resistant lines. A significant difference in GI50 between Iber-resistant H929 cells and control was found (1uM and >10uM respectively) with greater activity in the resistant cells. The same pattern was observed with the other resistant H929 cell lines, but not the resistant MM1s. Other pathway inhibitors are being explored. The expression of genes encoding SREBP pathway components was explored in the CoMMpass dataset. High SCD or MBTPS1 mRNA expression was associated with significantly worse PFS (logrank p<0.01), providing a further rationale for targeting the pathway. Conclusions Models representing multiple different IMiD/CELMoD resistance mechanisms have unified alterations in the SREBP pathway, highlighting a role in resistance biology and potential novel and targetable vulnerabilities. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract P3008: Endothelial Stearoyl-CoA Desaturase-1 Catalyzes Fatty Acid Metabolites To Mitigate Arterial Inflammation And Stiffness

Introduction: Vascular metabolic plasticity is intimately linked with endothelial homeostasis. Stearoyl-CoA desaturase-1 (SCD1), the enzyme that catalyzes the saturated long-chain fatty acids (FA) into monounsaturated FA (MUFA), is responsive to pulsatile shear stress (PSS), and is associated with cancer cell metabolism. We assessed whether exercise-mediated PSS activates PPARγ-SCD1 to mediate anti-inflammatory metabolites for vascular protection. Methods and Results: Human aortic endothelial cells (HAEC) were subjected to PSS (τ avg = 23±8 dyne/cm 2 at 1 Hz) for 4 hours, followed by metabolomic analysis. SCD1-mediated fatty acid metabolites, azelaic acid (AZA) and oleic acid (OA), were identified to mitigate NFκB luciferase activity and monocyte binding ( p &lt; 0.05, n= 5, vs. static condition). PSS upregulated PPARγ and SCD1 mRNA expression, whereas knockdown of PPARγ using siRNA downregulated SCD1. Wild type mice (C57BL/6J) undergoing 2-wk voluntary exercise developed increased perinuclear SCD1 expression in the aortic endothelium ( p &lt; 0.05, n=6, vs. sedentary controls), whereas SCD1 expression was reduced in PPARγ -dominant negative mice following exercise. LDLR -/- mice with endothelial-specific SCD1 deletion (SCD1 EC-KO : Cdh5 Cre , Scd1 f/f ) on 4-wk high-fat diet (HFD) developed significantly increased VCAM-1 and Oil Red O positive lesions in the aortic arch, whereas exercise or selective overexpression (OE) of SCD1 in endothelial cells by pAd5/F35/CD144 adenoviral vector mitigated the lesions ( p &lt; 0.05, n=5, HFD + exercise or HFD+Ad-SCD1 vs. HFD). Arterial stiffness as measured by Pulse Wave Velocity of the left common carotid was elevated in LDLR -/- SCD1 EC-KO on HF diet, but was decreased with exercise or SCD1 OE. Conclusion: PPARγ-SCD1 signaling is flow-responsive to mitigate arterial inflammation and stiffness. Despite SCD1-associated cancer cell metabolism, endothelial-specific SCD1 confers vascular protection, consistent with the reported skeletal muscle-specific model. Thus, we demonstrate that exercise activates PPARγ-SCD1 and SCD1 catalyzes AZA and OA as biomarkers with therapeutic potential.

TAMI-37. STEAROYL-COA DESATURASE 1 IS ESSENTIAL FOR THE GROWTH OF IDH MUTANT GLIOMA

Abstract BACKGROUND Increased de novo lipogenesis is a hallmark of cancer metabolism. In this study, we interrogated the role of de novo lipogenesis in IDH1 mutated glioma’s growth and identified the key enzyme, Stearoyl-CoA desaturase 1 (SCD1) that provides this growth advantage. MATERIALS ANDMETHODS We prepared genetically engineered glioma cell lines (U251 wild-type: U251WT and U251 IDHR132H mutant: U251RH) and normal human astrocytes (empty vector induced-NHA: NHAEV and IDHR132H mutant: NHARH). Lipid metabolic analysis was conducted by using LC-MS and Raman imaging microscopy. SCD1 expression was investigated by The Cancer Genome Atlas (TCGA) data analysis and Western-blotting method. Knock-out of SCD1 was conducted by using CRISPR/Cas9 and shRNA. RESULTS Previously, we showed that IDH1 mut glioma cells have increased monounsaturated fatty acids (MUFAs). TCGA data revealed IDH mut glioma shows significantly higher SCD1 mRNA expression than wild-type glioma. Our model systems of IDH1 mut (U251RH, NHARH) showed increased expression of this enzyme compared with their wild-type counterpart. Moreover, addition of D-2HG to U251WT increased SCD1 expression. Herein, we showed that inhibition of SCD1 with CAY10566 decreased relative cell number and sphere forming capacity in a dose-dependent manner. Furthermore, addition of MUFAs were able to rescue the SCD1 inhibitor induced-cell death and sphere forming capacity. Knock out of SCD1 revealed decreased cell proliferation and sphere forming ability. Decreasing lipid content from the media did not alter the growth of these cells, suggesting that glioma cells rely on de novo lipid synthesis rather than scavenging them from the microenvironment. CONCLUSION Overexpression of IDH mutant gene altered lipid composition in U251 cells to enrich MUFA levels and we confirmed that D-2HG caused SCD1 upregulation in U251WT. We demonstrated the glioma cell growth requires SCD1 expression and the results of the present study may provide novel insights into the role of SCD1 in IDH mut gliomas growth.

Gualou Xiebai Banxia decoction ameliorates Poloxamer 407-induced hyperlipidemia.

Ethnopharmacological relevance: Gualou Xiebai Banxia (GLXBBX) decoction is a well-known traditional Chinese herbal formula that was first discussed in the Synopsis of the Golden Chamber by Zhang Zhongjing in the Eastern Han Dynasty. In traditional Chinese medicine, GLXBBX is commonly prescribed to treat cardiovascular diseases, such as coronary heart disease and atherosclerosis.Objective: The present study aimed to examine GLXBBX’s preventative capacity and elucidate the potential molecular mechanism of Poloxamer 407 (P407)-induced hyperlipidemia in rats.Materials and methods: Both the control and model groups received pure water, and the test group also received a GLXBBX decoction. For each administration, 3 ml of the solution was administered orally. To establish hyperlipidemia, a solution mixed with 0.25 g/kg P407 dissolved in 0.9% normal saline was injected slowly into the abdominal cavity. At the end of the study, the rats’ plasma lipid levels were calculated using an automatic biochemical analyzer to evaluate the preventative capability of the GLXBBX decoction, and the serum and liver of the rats were collected.Results: The GLXBBX decoction significantly improved P407-induced hyperlipidemia, including increased plasma triglycerides (TGs), aspartate aminotransferase (AST) elevation, and lipid accumulation. Moreover, GLXBBX decoction treatment increased lipoprotein lipase (LPL) activity and mRNA expression of LPL. Furthermore, GLXBBX significantly suppressed the mRNA expression of stearoyl-CoA desaturase (SCD1).Conclusion: GLXBBX significantly improved P407-induced hyperlipidemia, which may have been related to enhanced LPL activity, increased LPL mRNA expression, and decreased mRNA expression of SCD1.

Comparison of performance, fatty acid composition, enzymes and gene expression between overfed Xupu geese with large and small liver

The aim of our study was to compare overfeeding performance, fatty acid composition, enzymes activity and gene expression between overfed Xupu geese with large and small liver. A total of sixty 80 d male Xupu geese were overfed by the same feed intake under the same conditions. The liver weight exhibited normal distribution. Based on the weight of liver, samples were divided into large liver (LL) and small liver (SL) Xupu geese. After overfeeding for 28 d: compared with the SL-Xupu geese, liver weight and liver-to-body weight ratio increased (p < .05), while abdominal fat weight and feed-to-liver weight ratio decreased (p < .05); the level of palmitic acid and methyltetracosanoate acid decreased (p < .05), and the level of oleic acid, linoleic acid, arachidonic acid, and docosahexaenoic acid increased (p < .05) in liver of LL-Xupu geese. Compared with the SL-Xupu geese, LL-Xupu geese had a higher plasma concentration of TG (triglyceride) (p < .05), and had a lower plasma concentration of VLDL-C (very low density lipoprotein cholesterol) (p < .05); and had a higher CHE (cholinesterase), LPS (lipase), LPL (lipoproteinlipase) activities (p < .05) in the liver. The mRNA expression of FABP4 (adipocyte fatty acid binding protein), SCD (stearoyl-CoA desaturase), FADS (fatty acid dehydrogenase), ELOVL1 (elongase of long-chain fatty acid 1), ACAT2 (acyl-Co A: cholesterol acyltransferase 2), and FASN (fatty acid synthase) (p < .05) were significantly upregulated in LL-Xupu geese than in SL-Xupu geese. The results showed that the level of unsaturated fatty acid in liver of LL-Xupu geese was higher than that of SL-Xupu geese, which may be closely related to enzymes and genes expression related to lipid metabolism. Highlights The content of unsaturated fatty acids in liver of LL-Xupu geese were significantly higher than in SL-Xupu geese. The mRNA expression of FABP4, SCD, FADS, ELOVL1, ACAT2, and FASN were significantly upregulated in LL-Xupu geese than in SL-Xupu geese. The level of unsaturated fatty acid in liver of LL-Xupu geese was higher than that of SL-Xupu geese, which may be closely related to enzymes and genes expression related to lipid metabolism.

PSXII-38 Differential expression of adipogenic genes in fetus longissimus dorsi during Hanwoo gestation periods

Abstract This study was conducted to investigate the mRNA expression of adipogenic makers in Hanwoo fetus during the pregnancy periods. Eighteen Hanwoo cows (Average body weight: 561 ± 90.1kg, Parity: 4.4 ± 2.6) were used for experimental animals. Artificial insemination was performed on all the experimental animals after estrus synchronization. Pregnant cows were slaughtered at 3 gestation periods. Three cows were harvested at 3 months of gestation, 6 cows at 6 months of gestation, and 9 cows at 9 months of gestation. After exsanguination, fetus was removed immediately by collecting the gravid uterus. After measuring the body weight and length of the fetus, sample of fetal longissimus dorsi (LD) were collected for mRNA expression and histological analysis. The relative level of mRNA expression for peroxisome proliferator-activated receptor γ (PPARγ), stearoyl-CoA desaturase (SCD), CCAAT/ enhancer-binding proteins β (C/EBPβ) were measured by real-time quantitative PCR. Data were analyzed using the GLM procedure, and compared using Tukey’s method at α = 0.05. The body weight and length of the fetus continued to increase as the fetus grew (P &amp;lt; 0.01), and it was confirmed that the growth rate progressed rapidly between the 6 and 9 months of the fetus. The adipocyte were observed from the age of 6 months of fetus, and were mainly formed around blood vessels. The level of PPARγ (P &amp;lt; 0.02) and SCD (P &amp;lt; 0.01) mRNA expression in LD were highest at 6 months of fetus, and the C/EBPβ expression was significantly increased as the fetus grew (P &amp;lt; 0.01). As a result of this study, it was confirmed that not only the adipocyte in LD of the fetus was formed at least after 3 months of gestation, but also the adipogenic makers was differentially expressed during the growth stage of the fetus.

MRNA expression of myogenic-adipogenic makers and adipocyte in skeletal muscle of Hanwoo calves at newborn and 6 months of age.

This study was conducted to compare the mRNA expression levels of myogenic-adipogenic makers in the skeletal muscle and adipocytes formation, body weight, rumen weight, and papilla length on Hanwoo calves at newborn and 6 months of age. Animals used three newborn Hanwoo calves (NC) and three Hanwoo calves 6 months of age (SC). Body weight and rumen weight were significantly increased in SC compared to NC (p < 0.01), and papilla length was longer about 10-fold in SC than NC. Adipocytes was possible to visually identify more adipocytes in SC compared to NC, and were mainly formed around the blood vessels. mRNA expression of myogenin, myosin heavy chain 1 and myosin heavy chain 2A in both longissimus dorsi (LD) and semimembranosus (SM) was found to increase with calves growth (p < 0.01), and it was confirmed that have higher levels of mRNA expression in SM than LD. In LD tissues, the mRNA expression of stearoyl-CoA desaturase (SCD, p < 0.03) and peroxisome proliferator activated receptor γ (PPARγ, p < 0.04) was significantly higher in SC than NC. In SM tissues, mRNA expression levels of SCD (p < 0.02) and CCAAT/enhancer binding protein β (C/EBPβ, p < 0.01) were higher in SC than NC, and also mRNA expression levels of PPARγ increased, but there was no significant difference. Thus, the calves period suggests that it is an important step in the development of the rumen and the myogenesis and adipogenesis.

Prohibitin 1 Deficiency Causes Impairment of Lipid Metabolism and the Disruption Is Deteriorated by Excessive Palmitic Acids in Hepatocytes (P08-106-19)

ObjectivesNon-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of lipid in hepatocytes. In spite of the growing number of NAFLD patients with the increased prevalence of obesity, the pathogenesis of NAFLD remains to be fully elucidated. Prohibitin1 (Phb1) is an evolutionarily conserved protein, which is expressed predominantly on the inner mitochondrial membrane. Several studies have provided evidences that the Phb1 plays a crucial role not only in proliferation of hepatocytes, but also in lipid metabolism in adipocytes. Since the liver is the major site for lipid metabolism, this study was aimed to understand the lipid metabolism regulated by Phb1 in hepatocytes. MethodsNormal murine hepatocyte cell line, AML12 was used in this study and Phb1 was disrupted by small interfering RNA (siRNA). These siRNA transfected cells were further treated with saturated fatty acids (SFAs), palmitic acid (PA) for 24 hours. Then the cell viability and the mRNA expression level of key enzymes involved in lipid metabolism were determined. ResultsApproximately 20% cell viability decreased when Phb1 was silenced and the cell viability diminished dramatically after PA treatment in both control and Phb1 deficiency groups. Without excessive fatty acids (FAs) inside the cells, Phb1 deficiency led to significant mRNA expression of stearoyl-CoA desaturase-1 (Scd1) to generate triglycerides (TG) and activated the endoplasmic reticulum (ER) stress response by upregulating the mRNA expression level of C/EBP homologous protein (Chop). The elevated expression of peroxisome proliferator activated receptor gamma (PPARγ), which was reported to be upregulated in the livers of NAFLD patients, was also found in this study. When intracellular FAs were surplus, the catabolism of FAs was inhibited by downregulation of carnitine palmitoyltransferase 1a (Ctp1a), while the synthesis of TG was further promoted by significantly increased mRNA expression level of Scd1. The elevated mRNA expression level of Chop and Pparγ induced by Phb1 disruption were further elevated. ConclusionsThis study, Phb1 deficiency led to altered lipid metabolism, resulting in the of lipid accumulation inside the cells and ER stress, and these cytotoxic effects were further deteriorated upon the excessive PA treatment. Funding SourcesNational Research Foundation of Korea, 2-1604-001.

Prepartum fatty acid supplementation in sheep. IV. Effect of calcium salts with eicosapentaenoic acid and docosahexaenoic acid in the maternal and finishing diet on lamb liver and adipose tissue during the lamb finishing period1.

The objective of this study was to evaluate the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation to ewes during late gestation on finishing lamb liver and adipose tissue fatty acid (FA) profile and gene expression. Lambs born from ewes supplemented with Ca salts of EPA + DHA, or palm FA distillate (PFAD) high in palmitic and oleic acid at 0.39% DM during the last 50 d of gestation were used. Lambs were weaned at 61 d of age and adapted to a high concentrate diet for 1.5 mo. After adaptation, 74 lambs (28 pens) were blocked by sex and BW and used in a 2 × 2 factorial arrangement of treatments using the factors of dam supplementation (DS) and lamb supplementation (LS) of Ca salts of EPA + DHA or PFAD at 1.48% DM. Lambs were slaughtered after 42 d and liver and adipose tissue collected for FA and gene expression analysis. Liver concentrations of EPA and DHA were greater (P < 0.01) with LS of EPA + DHA vs. PFAD during the finishing period. In adipose tissue, a lamb × dam interaction was observed for EPA (P = 0.02) and DHA (P = 0.04); LS of EPA + DHA increased EPA and DHA, but the increase was greatest in lambs born from ewes supplemented with PFAD. No lamb × dam treatment interactions were observed for gene expression in liver tissue (P > 0.10). Hepatic mRNA abundance of hormone-sensitive lipase (HSL; P = 0.01) was greater in lambs born from EPA + DHA ewes vs. lambs from PFAD ewes. mRNA expression of stearoyl-CoA desaturase (P < 0.01), fatty acid synthase (P = 0.01), Δ5-desaturase (P < 0.01), and Δ6-desaturase (P < 0.01) were decreased in liver of EPA + DHA lambs. A significant lamb × dam diet interaction was observed for elongation of very long chain fatty acid 2 in adipose tissue (P = 0.01); lambs supplemented with the same FA as their dams had lower expression. Expression of HSL tended (P = 0.08) to be decreased in adipose of EPA + DHA lambs born from EPA + DHA ewes. The changes in mRNA expression suggest that lipogenesis decreased, and lipolysis increased in lamb liver with EPA + DHA vs. PFAD supplementation during the finishing period. In adipose tissue, changes suggest that lipogenesis decreased in lambs born from EPA + DHA supplemented dams and supplemented with EPA + DHA during the finishing period. In addition, these results suggest an interaction between supplementation of FA to dams during late gestation on lamb response of adipose tissue, but not liver, to FA supplementation during the finishing period.

Influences of sterol regulatory element binding protein-1c silencing on glucose production in HepG2 cells treated with free fatty acid

BackgroundElevation of exogenous free fatty acid (FFA) level leads to insulin resistance (IR) in liver, IR is manifested by elevated hepatic glucose production. We aim to study whether inhibition of endogenous fatty acid synthesis could decrease hepatic glucose production.MethodsLow-passage HepG2 cells derived from human liver tissue were cultured in medium supplemented with FFA to induce IR, the influences of sterol regulatory element binding protein-1c (SREBP-1c) silencing on glucose production of HepG2 cells were investigated, and genes responsible for fatty acid and glucose metabolism were detected by real-time PCR.ResultsCompared with HepG2 cells cultured in normal growth medium, glucose production of HepG2 cells treated by FFA was significantly increased {[(0.28 ± 0.01) vs (0.83 ± 0.02)] umol.ug− 1 protein, n = 6 wells, P < 0.01}; the mRNA expression of phosphoenolpyruvate carboxylase kinase (PEPCK) and glucose-6-phosphatase (G6PC) in HepG2 cells increased by more than 5-fold and 3-fold, respectively; the mRNA expression of fatty acid synthase (FAS) and stearoyl-CoA desaturase-1 (SCD1) increased by approximately 4-fold and 1.1-fold, respectively; the mRNA expression of carnitine palmitoyltransferase-1 (CPT-1) changed slightly. Compared with the scrambled siRNA control, glucose production of HepG2 cells treated by FFA significantly increased after SREBP-1c silencing {[(0.018 ± 0.001) vs (0.028 ± 0.002)] umol.ug− 1 protein, n = 6 wells, P < 0.01}; the mRNA expression of PEPCK and G6PC increased by approximately 1.5-fold and 5-fold, respectively, but the mRNA expression of FAS, SCD1 and CPT-1 changed slightly.ConclusionsSREBP-1c silencing further augmented glucose production of HepG2 cells treated by FFA significantly, genes responsible for fatty acid synthesis and gluconeogenesis played an important role in this process. SREBP-1c functions not only as a lipid regulator but also plays an important role in regulation of glucose metabolism.

Association Study and Expression Analysis of Stearoyl Co-A Desaturase as a Candidate Gene for Fatty Acid Composition in Indonesian Crossbred Chickens

Background and Objective: The stearoyl-CoA desaturase (SCD) gene encodes an enzyme involved in fatty acid (FA) biosynthesis. The aim of the present study was to investigate the association and expression of SCD as a candidate gene for FA composition in Indonesian crossbred chickens. Materials and Methods: Sixty-two Indonesian crossbred, unsexed chickens (F2 Kampung×broilers) were used. FA composition was measured at 12 weeks of age from thigh meat of crossbred chicken. Results: A single nucleotide polymorphism in coding region c.17492542 C>G of SCD was associated with FA composition, including both unsaturated [linoleic (C18:2n6c) and eicosadienoic (C20:2) acids] and saturated [lauric acid (C12:0)] forms. SCD mRNA expression analysis in liver revealed 6 chickens with extremely high and low FA compositions, of them, high FA birds (n = 3) had higher unsaturated and lower saturated FAs, while the low FA group (n = 3) had lower unsaturated and higher saturated FA levels. SCD expression was higher (p<0.05) in tissues collected from high FA chickens than low FA chickens. Conclusion: These results will improve the understanding of SCD function in FA composition and will shed light on SCD as a potential candidate in the selection of chickens with higher levels of unsaturated and lower levels of saturated FA.

Neonatal overfeeding induced glucocorticoid overexposure accelerates hepatic lipogenesis in male rats

BackgroundPostnatal overfeeding activates tissue glucocorticoid (GC) activity by up-regulating 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) and increasing sensitivity to high-fat (HF) diet-induced non-alcoholic fatty liver disease (NAFLD). The present study aimed to evaluate the effects of postnatal overfeeding on GC regulation and lipogenesis in the liver and to observe the impact of GC on hepatocyte lipid metabolism.MethodsIn vivo, Male Sprague-Dawley rat pup litters were adjusted to litter sizes of three (small litter, SL) or ten (normal litter, NL) on postnatal day 3 and then given standard chow from postnatal week 3 (W3) to W13. In vitro, HepG2 cells were stimulated by GC, mifepristone (Mi) or GC + Mi within 48 h, followed by sodium oleate (OA) intervention (or not) for 24 h. Intracellular lipid droplets, triglyceride (TG) concentrations and gene expression related to lipid metabolism were measured in hepatic tissues or HepG2 cells.ResultsIn vivo, weight gain in the body and liver and TG concentrations in the liver were significantly increased in the SL rats compared to the NL rats at W3 and W13 (p < 0.05); mRNA expression of hepatic 11β-HSD1, acetyl-CoA carboxylase 1 (ACC), stearoyl-CoA desaturase-1 (SCD1), fatty acid synthase (FASN) and their nuclear transcription factor, sterol regulatory element binding protein-1c (SREBP-1c) (p < 0.05), was also increased. In vitro, intracellular lipid droplets and TG content in HepG2 cells increased under stimulation with GC or OA (p < 0.05); the increase was more significant following treatment with GC and OA together (p < 0.05). The ACC, SCD1, FASN and SREBP-1c mRNA expression changes were highly similar to the changes in TG content in cells. All the changes induced by GC disappeared when the glucocorticoid receptor (GR) was blocked by Mi.ConclusionsPostnatal overfeeding induced GC overexposure through 11β-HSD1 up-regulation in the liver. GC activated hepatic de novo lipogenesis (DNL) via GR and led to hepatic lipid accumulation, which increased the risk of NAFLD during adulthood.

Fatty acid elongase 5 (ELOVL5) alters the synthesis of long-chain unsaturated fatty acids in goat mammary epithelial cells

Increased production of long-chain unsaturated fatty acids (LCUFA) can have a positive effect on the nutritional value of ruminant milk for human consumption. In nonruminant species, fatty acid elongase 5 (ELOVL5) is a key enzyme for endogenous synthesis of long-chain unsaturated fatty acids. However, whether ELOVL5 protein plays a role (if any) in ruminant mammary tissue remains unclear. In the present study, we assessed the mRNA abundance of ELOVL5 at 3 stages of lactation in goat mammary tissue. Results revealed that ELOVL5 had the lowest expression at peak lactation compared with the nonlactating and late-lactating periods. The ELOVL5 was overexpressed or knocked down to assess its role in goat mammary epithelial cells. Results revealed that ELOVL5 overexpression increased the expression of perilipin2 (PLIN2) and decreased diacylglycerolacyltransferase 2 (DGAT2) and fatty acid desaturase 2 (FADS2) mRNA, but had no effect on the expression of DGAT1, FADS1, and stearoyl-CoA desaturase 1 (SCD1). Overexpression of ELOVL5 decreased the concentration of C16:1n-7, whereas no significant change in C18:1n-7 and C18:1n-9 was observed. Knockdown of ELOVL5 decreased the expression of PLIN2 but had no effect on DGAT1, DGAT2, FADS1, FADS2, and SCD1 mRNA expression. Knockdown of ELOVL5 increased the concentration of C16:1n-7 and decreased that of C18:1n-7. The alterations of expression of genes related to lipid metabolism after overexpression or knockdown of ELOVL5 suggested a negative feedback regulation by the products of ELOVL5 activation. However, the content of triacylglycerol was not altered by knockdown or overexpression of ELOVL5 in goat mammary epithelial cells, which might have been due to the insufficient availability of substrate in vitro. Collectively, these are the first in vitro results highlighting an important role of ELOVL5 in the elongation of 16-carbon to 18-carbon unsaturated fatty acids in ruminant mammary cells.

GLP-1 Elicits an Intrinsic Gut–Liver Metabolic Signal to Ameliorate Diet-Induced VLDL Overproduction and Insulin Resistance

Perturbations in hepatic lipid and very-low-density lipoprotein (VLDL) metabolism are involved in the pathogenesis of obesity and hepatic insulin resistance. The objective of this study is to delineate the mechanism of subdiaphragmatic vagotomy in preventing obesity, hyperlipidemia, and insulin resistance. By subjecting the complete subdiaphragmatic vagotomized mice to various nutritional conditions and investigating hepatic de novo lipogenesis pathway, we found that complete disruption of subdiaphragmatic vagal signaling resulted in a significant decrease of circulating VLDL-triglyceride compared with the mice obtained sham procedure. Vagotomy further prevented overproduction of VLDL-triglyceride induced by an acute fat load and a high-fat diet-induced obesity, hyperlipidemia, hepatic steatosis, and glucose intolerance. Mechanistic studies revealed that plasma glucagon-like peptide-1 was significantly raised in the vagotomized mice, which was associated with significant reductions in mRNA and protein expression of SREBP-1c (sterol regulatory element-binding protein 1c), SCD-1 (stearoyl-CoA desaturase-1), and FASN (fatty acid synthase), as well as enhanced hepatic insulin sensitivity. In vitro, treating mouse primary hepatocytes with a glucagon-like peptide-1 receptor agonist, exendin-4, for 48 hours inhibited free fatty acid, palmitic acid treatment induced de novo lipid synthesis, and VLDL secretion from hepatocytes. Elevation of glucagon-like peptide-1 in vagotomized mice may prevent VLDL overproduction and insulin resistance induced by high-fat diet. These novel findings, for the first time, delineate an intrinsic gut-liver regulatory circuit that is mediated by glucagon-like peptide-1 in regulating hepatic energy metabolism.

Increased lipogenesis in spite of upregulated hepatic 5'AMP-activated protein kinase in human non-alcoholic fatty liver.

Molecular adaptations in human non-alcoholic fatty liver disease (NAFLD) are incompletely understood. This study investigated the main gene categories related to hepatic de novo lipogenesis and lipid oxidation capacity. Liver specimens of 48 subjects were histologically classified according to steatosis severity. In-depth analyses were undertaken using real-time polymerase chain reaction, immunoblotting, and immunohistochemistry. Lipid profiles were analyzed by gas chromatography/flame ionization detection, and effects of key fatty acids were studied in primary human hepatocytes. Real-time polymerase chain reaction, immunoblotting, and immunohistochemistry indicated 5'AMP-activated protein kinase (AMPK) to be increased with steatosis score ≥ 2 (all P <0.05), including various markers of de novo lipogenesis and lipid degradation (all P <0.05). Regarding endoplasmic reticulum stress, X-Box binding protein-1 (XBP1) was upregulated in steatosis score ≥ 2 (P = 0.029) and correlated with plasma palmitate (r = 0.34; P = 0.035). Palmitate incubation of primary human hepatocytes increased XBP1 and downstream stearoyl CoA desaturase-1 mRNA expression (both P <0.05). Moreover, plasma and liver tissue exposed a NAFLD-related lipid profile with reduced polyunsaturated/saturated fatty acid ratio, increased palmitate and palmitoleate, and elevated lipogenesis and desaturation indices with steatosis score ≥ 2 (all P <0.05). In humans with advanced fatty liver disease, hepatic AMPK protein is upregulated, potentially in a compensatory manner. Moreover, pathways of lipid synthesis and degradation are co-activated in subjects with advanced steatosis. Palmitate may drive lipogenesis by activating XBP1-mediated endoplasmic reticulum stress and represent a target for future dietary or pharmacological intervention.

Effect of hypoxia-inducible factor-2α/stearoyl-CoA desaturase-1 pathway on biological behaviors of hepatoma cells induced by hypoxia

Objective: To investigate whether hypoxia-inducible factor-2α (HIF-2α) affects the biological behaviors of hepatoma cells through regulating stearoyl-CoA desaturase-1 (SCD1) in a hypoxic environment. Methods: HepG2 and SMMC-7721 cells were exposed to 1% O2 to establish the hypoxic models. After hepatoma cells were stimulated by hypoxia for 0, 3, 6, 12, and 24 hours, fluorescent quantitative PCR and Western blot were used to measure the mRNA and protein expression of HIF-2α and SCD1 over time. HIF-2α interfering plasmids and SCD1 inhibitor CAY10566 were used to divide the cells into blank group (nomoxia), hypoxic group (1% O2 for 12 h), hypoxic negative control group (negative HIF-2α plasmid+1% O2 for 12 h), hypoxic interference group (HIF-2α interfering plasmid+1% O2 for 12 h), hypoxic CAY group (CAY10566 10 μmol+1% O2 for 12 h), and hypoxic interference+CAY group (HIF-2α interfering plasmid+CAY10566 10 μmol+1% O2 for 12 h). Western blot was used to measure the protein expression of HIF-2α and SCD1 in hepatoma cells, CCK8 assay was used to measure the proliferative capacity of hepatoma cells, Annexin-V/PE flow cytometry was used to measure the apoptosis of hepatoma cells, and transwell invasion assay was used to measure the invasion of hepatoma cells. A one-way analysis of variance was used to compare the means of multiple samples. Results: Both HepG2 and SMMC-7721 cells showed increasing mRNA and protein expression of HIF-2α and SCD1 over the time of hypoxic induction. After the expression of HIF-2α was downregulated in a hypoxic environment, hepatoma cells showed a significant reduction in the protein expression of SCD1; inhibition of SCD1 expression had no significant effect on the protein expression of HIF-2α in hepatoma cells. After HIF-2α was interfered with and SCD1 expression was inhibited, HepG2 and SMMC-7721 cells showed significantly greater reduction in the protein expression of SCD1 than those with HIF-2α or SCD1 inhibition alone (0.53±0.04 vs 1.12±0.04 or 1.12±0.04; 0.44±0.10 vs 0.90±0.10 or 0.99±0.13) (HIF-2α: FhepG2 = 1026.89, PhepG2 = 0.00, FSMMC-7721 = 2186.22, PSMMC-7721 = 0.00; SCD1: FhepG2 = 1347.93, PhepG2 = 0.00, FSMMC-7721 = 46.43, PSMMC-7721 = 0.00). Inhibition of the expression of HIF-2α or SCD1 reduced the proliferation and invasion of HepG2 and SMMC-7721 cells and promoted apoptosis (P < 0.05); interference and downregulation of HIF-2α combined with inhibition of SCD1 expression by CAY10566 achieved significantly greater reductions in proliferation and invasion and a significantly greater increase in apoptosis rate of hepatoma cells, compared with inhibition of HIF-2α or SCD1 alone (P <0.05). Conclusion: HIF-2α/SCD1 pathway may be one of the important mechanisms for hypoxia to regulate the energy metabolism of hepatoma cells and affect their biological behaviors.

Inhibition of fatty acid desaturation is detrimental to cancer cell survival in metabolically compromised environments.

BackgroundEnhanced macromolecule biosynthesis is integral to growth and proliferation of cancer cells. Lipid biosynthesis has been predicted to be an essential process in cancer cells. However, it is unclear which enzymes within this pathway offer the best selectivity for cancer cells and could be suitable therapeutic targets.ResultsUsing functional genomics, we identified stearoyl-CoA desaturase (SCD), an enzyme that controls synthesis of unsaturated fatty acids, as essential in breast and prostate cancer cells. SCD inhibition altered cellular lipid composition and impeded cell viability in the absence of exogenous lipids. SCD inhibition also altered cardiolipin composition, leading to the release of cytochrome C and induction of apoptosis. Furthermore, SCD was required for the generation of poly-unsaturated lipids in cancer cells grown in spheroid cultures, which resemble those found in tumour tissue. We also found that SCD mRNA and protein expression is elevated in human breast cancers and predicts poor survival in high-grade tumours. Finally, silencing of SCD in prostate orthografts efficiently blocked tumour growth and significantly increased animal survival.ConclusionsOur data implicate lipid desaturation as an essential process for cancer cell survival and suggest that targeting SCD could efficiently limit tumour expansion, especially under the metabolically compromised conditions of the tumour microenvironment.Electronic supplementary materialThe online version of this article (doi:10.1186/s40170-016-0146-8) contains supplementary material, which is available to authorized users.

Conjugated linoleic acids influence fatty acid metabolism in ovine ruminal epithelial cells

Conjugated linoleic acids (CLA), particularly cis-9,trans-11 (c9t11) and trans-10,cis-12 (t10c12), are used as feed additives to adapt to constantly increasing demands on the performance of lactating cows. Under these feeding conditions, the rumen wall, and the rumen epithelial cells (REC) in particular, are directly exposed to high amounts of CLA. This study determined the effect of CLA on the fatty acid (FA) metabolism of REC and expression of genes known to be modulated by FA. Cultured REC were incubated with c9t11, t10c12, and the structurally similar FA linoleic acid (LA), oleic acid (OA), and trans-vaccenic acid (TVA) for 48 h at a concentration of 100µM. Cellular FA levels were determined by gas chromatography. Messenger RNA expression levels of stearoyl-CoA desaturase (SCD) and monocarboxylate transporter (MCT) 1 and 4 were quantified by reverse transcription-quantitative PCR. Fatty acid evaluation revealed significant effects of CLA, LA, OA, and TVA on the amount of FA metabolites of β-oxidation and elongation and of metabolites related to desaturation by SCD. The observed changes in FA content point (among others) to the ability of REC to synthesize c9t11 from TVA endogenously. The mRNA expression levels of SCD identified a decrease after CLA, LA, OA, or TVA treatment. In line with the changes in mRNA expression, we found reduced amounts of C16:1n-7 cis-9 and C18:1n-9 cis-9, the main products of SCD. The expression of MCT1 mRNA increased after c9t11 and t10c12 treatment, and CLA c9t11 induced an upregulation of MCT4. Application of peroxisome proliferator-activated receptor (PPAR) α antagonist suggested that activation of PPARα is involved in the changes of MCT1, MCT4, and SCD mRNA expression induced by c9t11. Participation of PPARγ in the changes of MCT1 and SCD mRNA expression was shown by the application of the respective antagonist. The study demonstrates that exposure to CLA affects both FA metabolism and regulatory pathways within REC.