Protein engineering: Regulatory perspectives of stearoyl CoA desaturase

SREBP-1-mediated lipogenesis confers resistance to ferroptosis and improves endothelial injury

Atherosclerosis refers to a disease characterized by the formation of lipid plaque deposits within arterial walls, leading to reduced blood flow or blockage of blood outflow. The process of endothelial injury induced by oxidized low-density lipoprotein (ox-LDL) is considered the initial stage of atherosclerosis. Ferroptosis is a form of iron-dependent, non-apoptotic cell death, and current research suggests its association with coronary artery disease (CAD). In this study, we observed a correlation between reduced expression of SREBP-1 and the occurrence of stable CAD. Additionally, during the process of endothelial injury induced by ox-LDL, we also noted decreased expression of the SREBP-1/SCD1/FADS2 and involvement in the ferroptosis process. Mechanistically, ox-LDL induced endothelial injury by inhibiting the lipid biosynthesis process mediated by the SREBP-1/SCD1/FADS2, thereby inducing lipid peroxidation and ferroptosis. On the contrary, overexpression of SREBP-1 or supplementation with monounsaturated fatty acids counteracted iron accumulation, mitochondrial damage, and lipid peroxidation-induced ferroptosis, thereby improving endothelial injury. Our study indicated that the decreased expression of peripheral blood SREBP-1 mRNA is an independent risk factor for stable CAD. Furthermore, in endothelial cells, the lipid biosynthesis process mediated by SREBP-1 could ameliorate endothelial injury by resisting ferroptosis. The study has been registered with the Chinese Clinical Trial Registry, which serves as a primary registry in the World Health Organization International Clinical Trials Registry Platform (ChiCTR2300074315, August 3rd, 2023).

Rapid Movement of Palmitoleic Acid from Phosphatidylcholine to Phosphatidylinositol in Activated Human Monocytes

This work describes a novel route for phospholipid fatty acid remodeling involving the monounsaturated fatty acid palmitoleic acid. When administered to human monocytes, palmitoleic acid rapidly incorporates into membrane phospholipids, notably into phosphatidylcholine (PC). In resting cells, palmitoleic acid remains within the phospholipid pools where it was initially incorporated, showing no further movement. However, stimulation of the human monocytes with either receptor-directed (opsonized zymosan) or soluble (calcium ionophore A23187) agonists results in the rapid transfer of palmitoleic acid moieties from PC to phosphatidylinositol (PI). This is due to the activation of a coenzyme A-dependent remodeling route involving two different phospholipase A2 enzymes that act on different substrates to generate free palmitoleic acid and lysoPI acceptors. The stimulated enrichment of specific PI molecular species with palmitoleic acid unveils a hitherto-unrecognized pathway for lipid turnover in human monocytes which may play a role in regulating lipid signaling during innate immune activation.

Sanghuangporus vaninii extract ameliorates hyperlipidemia in rats by mechanisms identified with transcriptome analysis

The increasing incidence of hyperlipidemia is a serious threat to public health. The development of effective and safe lipid-lowering drugs with few side effects is necessary. The purpose of this study was to assess the lipid-lowering activity of Sanghuangporus vaninii extract (SVE) in rat experiments and reveal the molecular mechanism by transcriptome analysis. Hyperlipidemia was induced in the animals using a high-fat diet for 4 weeks. At the end of the 4th week, hyperlipidemic rats were assigned into two control groups (model and positive simvastatin control) and three treatment groups that received SVE at 200, 400, or 800 mg kg-1 day-1 for another 4 weeks. A last control group comprised normal chow-fed rats. At the end of the 8th week, rats were sacrificed and lipid serum levels, histopathology, and liver transcriptome profiles were determined. SVE was demonstrated to relieve the lipid disorder and improve histopathological liver changes in a dose-dependent manner. The transcriptomic analysis identified changes in hepatocyte gene activity for major pathways including steroid biosynthesis, bile secretion, cholesterol metabolism, AMPK signaling, thyroid hormone signaling, and glucagon signaling. The changed expression of crucial genes in the different groups was confirmed by qPCR. Collectively, this study revealed that SVE could relieve hyperlipidemia in rats, the molecular mechanism might be to promote the metabolism of lipids and the excretion of cholesterol, inhibit the biosynthesis of cholesterol by activating the AMPK signaling pathway, the thyroid hormone signaling pathway, and the glucagon signaling pathway.

SCD1 is the critical signaling hub to mediate metabolic diseases: Mechanism and the development of its inhibitors

Metabolic diseases, featured with dysregulated energy homeostasis, have become major global health challenges. Patients with metabolic diseases have high probability to manifest multiple complications in lipid metabolism, e.g. obesity, insulin resistance and fatty liver. Therefore, targeting the hub genes in lipid metabolism may systemically ameliorate the metabolic diseases, along with the complications. Stearoyl-CoA desaturase 1(SCD1) is a key enzyme that desaturates the saturated fatty acids (SFAs) derived from de novo lipogenesis or diet to generate monounsaturated fatty acids (MUFAs). SCD1 maintains the metabolic and tissue homeostasis by responding to, and integrating the multiple layers of endogenous stimuli, which is mediated by the synthesized MUFAs. It critically regulates a myriad of physiological processes, including energy homeostasis, development, autophagy, tumorigenesis and inflammation. Aberrant transcriptional and epigenetic activation of SCD1 regulates AMPK/ACC, SIRT1/PGC1α, NcDase/Wnt, etc, and causes aberrant lipid accumulation, thereby promoting the progression of obesity, non-alcoholic fatty liver, diabetes and cancer. This review critically assesses the integrative mechanisms of the (patho)physiological functions of SCD1 in metabolic homeostasis, inflammation and autophagy. For translational perspective, potent SCD1 inhibitors have been developed to treat various types of cancer. We thus discuss the multidisciplinary advances that greatly accelerate the development of SCD1 new inhibitors. In conclusion, besides cancer treatment, SCD1 may serve as the promising target to combat multiple metabolic complications simultaneously.

De Novo Biosynthesis of Free Vaccenic Acid with a Low Content of Oleic Acid in Saccharomyces cerevisiae

Omega-7 (ω-7) fatty acids have potential application in the fields of nutraceutical, agricultural, and food industry. The natural ω-7 fatty acids are currently from plants or vegetable oils, which are unsustainable and limited by the availability of plant sources. Here, we developed an innovative biosynthetic route to produce vaccenic acid (C18:1 ω-7) while minimizing oleic acid (C18:1 ω-9) content in Saccharomyces cerevisiae. We have engineered S. cerevisiaeto produce C18:1 ω-7 by expressing a fatty acid elongase from Rattus norvegicus. To reduce the content of C18:1 ω-9, the endogenous desaturase Ole1 was replaced by the desaturase, which has specific activity on palmitoyl-coenzyme A (C16:0-CoA). Finally, the production of free C18:1 ω-7 was improved by optimizing the source of cytochrome b5 and overexpressing endoplasmic reticulum chaperones. After combining these strategies, the yield of C18:1 ω-7 was increased from 0 to 9.3 mg/g DCW and C18:1 ω-9 was decreased from 25.2 mg/g DCW to 1.6 mg/g DCW. This work shows a de novo synthetic pathway to produce the highest amount of free C18:1 ω-7 with a low content of C18:1 ω-9 in S. cerevisiae.

TGF-β1 promotes SCD1 expression via the PI3K-Akt-mTOR-SREBP1 signaling pathway in lung fibroblasts

BACKGROUND

Lung fibroblast activation is associated with airway remodeling during asthma progression. Stearoyl-CoA desaturase 1 (SCD1) plays an important role in the response of fibroblasts to growth factors. This study aimed to explore the effects of SCD1 on fibroblast activation induced by transforming growth factor-β1 (TGF-β1) and the role of the phosphatidylinositol-3-kinase-AKT serine-threonine protein kinase-mechanistic target of rapamycin (PI3K-Akt-mTOR) pathway on the regulation of SCD1 expression in airway remodeling.

METHODS

Female C57BL/6 mice were sensitized and challenged with house dust mites to generate a chronic asthma model. The inhibitor of SCD1 was injected i.g. before each challenge. The airway hyper-responsiveness to methacholine was evaluated, and airway remodeling and airway inflammation were assessed by histology. The effects of SCD1 on fibroblast activation were evaluated in vitro using an SCD1 inhibitor and oleic acid and via the knockdown of SCD1. The involvement of the PI3K-Akt-mTOR-sterol regulatory element-binding protein 1 (SREBP1) pathway in lung fibroblasts was investigated using relevant inhibitors.

RESULTS

The expression of SCD1 was increased in fibroblasts exposed to TGF-β1. The inhibition of SCD1 markedly ameliorated airway remodeling and lung fibroblast activation in peripheral airways. The knockdown or inhibition of SCD1 resulted in significantly reduced extracellular matrix production in TGF-β1-treated fibroblasts, but this effect was reversed by the addition of exogenous oleic acid. The PI3K-Akt-mTOR-SREBP1 pathway was found to be involved in the regulation of SCD1 expression and lung fibroblast activation.

CONCLUSIONS

The data obtained in this study indicate that SCD1 expression contributes to fibroblast activation and airway remodeling and that the inhibition of SCD1 may be a therapeutic strategy for airway remodeling in asthma.

Complex Interactions Between Circulating Fatty Acid Levels, Desaturase Activities, and the Risk of Gestational Diabetes Mellitus: A Prospective Cohort Study

Objective

Maternal abnormal fatty acid desaturation has previously been linked to gestational diabetes mellitus (GDM). However, few studies have investigated this relationship longitudinally throughout pregnancy. In this study, we investigated the relationship between GDM and desaturase activities across the pregnancy trimesters.

Methods

A total of 661 women (GDM = 189, non-GDM = 472) were selected from the Complex Lipids in Mothers and Babies (CLIMB) cohort study. Clinical information and maternal serum were collected at 11–14, 22–28, and 32–34 weeks of gestation. Totally, 20 serum fatty acids were quantified using gas chromatography–mass spectrometry (GC-MS) analysis at each timepoint. Polyunsaturated fatty acid (PUFA) product-to-precursor ratios were used to estimate desaturase and elongase activities including delta-5 desaturase, delta-6 desaturase, stearoyl-CoA desaturase, and elongase.

Results

After adjusting for major potential confounders including maternal age, BMI, primiparity, smoking, and alcohol consumption, we observed a significant increase in the levels of γ-linolenic acid (GLA) and eicosatrienoic acid (DGLA) in the first trimester of women with GDM, whereas GLA and DGLA were reduced in the third trimester, when compared to the non-GDM group. Arachidonic acid (AA) showed an upward trend in the GDM group throughout pregnancy. Estimated delta-6 desaturase and delta-5 desaturase activity were elevated in the first trimester (OR = 1.40, 95% CI 1.03–1.91; OR = 0.56, 95% CI 0.32–0.96) but attenuated in the third trimester (OR = 0.78, 95% CI 0.58–1.07; OR = 2.64, 95% CI 1.46–4.78) in GDM pregnancies, respective to controls. Estimated delta-9–18 desaturase activity (OR = 3.70, 95% CI 1.49–9.19) was increased in women with GDM in later pregnancy.

Conclusions

Our study highlights the potential importance of fatty acid desaturase activities, particularly estimated delta-5 desaturase and delta-9–18 desaturase in the pathophysiology of GDM. These findings may have applications for the early diagnosis and management of GDM.

Roles of Palmitoleic Acid and Its Positional Isomers, Hypogeic and Sapienic Acids, in Inflammation, Metabolic Diseases and Cancer

In the last few years, the monounsaturated hexadecenoic fatty acids are being increasingly considered as biomarkers of health with key functions in physiology and pathophysiology. Palmitoleic acid (16:1n-7) and sapienic acid (16:1n-10) are synthesized from palmitic acid by the action of stearoyl-CoA desaturase-1 and fatty acid desaturase 2, respectively. A third positional isomer, hypogeic acid (16:1n-9) is produced from the partial β-oxidation of oleic acid. In this review, we discuss the current knowledge of the effects of palmitoleic acid and, where available, sapienic acid and hypogeic acid, on metabolic diseases such as diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and cancer. The results have shown diverse effects among studies in cell lines, animal models and humans. Palmitoleic acid was described as a lipokine able to regulate different metabolic processes such as an increase in insulin sensitivity in muscle, β cell proliferation, prevention of endoplasmic reticulum stress and lipogenic activity in white adipocytes. Numerous beneficial effects have been attributed to palmitoleic acid, both in mouse models and in cell lines. However, its role in humans is not fully understood, and is sometimes controversial. Regarding sapienic acid and hypogeic acid, studies on their biological effects are still scarce, but accumulating evidence suggests that they also play important roles in metabolic regulation. The multiplicity of effects reported for palmitoleic acid and the compartmentalized manner in which they often occur, may suggest the overlapping actions of multiple isomers being present at the same or neighboring locations.

Adipose Dysfunction in Adulthood Insulin Resistance of Low-Birth Weight Mice: A Proteomics Study

PURPOSE

To investigate changes in the protein expression profile of white adipose tissue in low-birth weight (LBW) mice with high-fat diets using tandem mass tag (TMT) and liquid chromatography-mass spectrometry (LC-MS/MS) and parallel reaction monitoring (PRM).

METHODS

Institute of Cancer Research (ICR) mice were used to establish an LBW model using malnutrition during pregnancy. Male pups were randomly selected from LBW and normal-birth weight (NBW) offspring, then all given a high-fat diet. Blood glucose, serum insulin, total cholesterol (TC) and triglyceride (TG) levels were measured. The weight ratio of liver, muscle, and adiposity index were calculated. Hematoxylin and eosin staining was used to visualize adipose tissue morphology. Oil red O staining of liver and TG content of muscle were used to determine ectopic lipid deposition. TMT combined with LC-MS/MS was used to analyze protein expression in white adipose tissue. PRM and Western blot were used to verify the expression of CD36, SCD1, PCK1 and PPARγ.

RESULTS

Compared with NBW mice, fasting blood glucose, insulin and HOMA-IR significantly increased in LBW mice, indicating insulin resistance and impaired glucose regulation; TC, TG, adipocyte size, and adiposity index were increased in LBW mice, suggesting obesity and disorder of lipid metabolism. We observed ectopic lipid deposition in liver and muscle. There were 996 differentially expressed proteins (DEPs) in the LBW/NBW groups. Peroxisome proliferator-activated receptor (PPAR) was a relatively important signaling pathway regulating metabolic process in functional enrichment analysis of DEPs. Up-regulated expression of CD36, SCD1, and PCK1 in the adipose tissue of LBW mice was observed through PPAR pathways cluster analysis. And PRM and Western blot assay validated the proteomics findings.

CONCLUSION

When exposed to high-fat diets, LBW mice exhibited insulin resistance and disorder of lipid metabolism compared with NBW mice. The expression of PPARγ was elevated, as well as upstream CD36, downstream SCD1 and PCK1 of the PPARγ in the adipose tissue of LBW mice. It was suggested that the activation in CD36/PPARγ/SCD1 and CD36/PPARγ/PCK1 pathways may induce adipose dysfunction, thereby increasing susceptibility to insulin resistance.

Palmitoleic acid ameliorates palmitic acid-induced proinflammation in J774A.1 macrophages via TLR4-dependent and TNF-α-independent signallings

Adipose tissue resident macrophages play an important role in the regulation of the inflammatory response. Monounsaturated fatty acids assist in the prevention of cardiovascular diseases via an anti-inflammatory effect. However, the mechanisms by which monounsaturated fatty acids, such as palmitoleic acid, regulate the inflammatory response has not been well investigated. In this study, we found that a high concentration of palmitic acid induced J774A.1 murine macrophages toward a pro-inflammatory state, possibly through the activation of the TLR2 or TLR4 genes, and their downstream signaling pathways. In contrast, palmitoleic acid induced a protective effect against inflammation in macrophage of non-obese rodents by inducing an alternative activation pathway via reducing TLR2 or TLR4 signaling. This study indicates that the balance of palmitic acid (saturated fatty acid) and palmitoleic acid (monounsaturated fatty acid) effects macrophage activation. The potential therapeutic impact of palmitoleic acid to ameliorate non-obese-mediated inflammation warrants further investigation.

Effects of maternal dietary omega-3 polyunsaturated fatty acids and methionine during late gestation on fetal growth, DNA methylation, and mRNA relative expression of genes associated with the inflammatory response, lipid metabolism and DNA methylation in placenta and offspring's liver in sheep

BACKGROUND

Omega-3 PUFA or methionine (Met) supply during gestation alters offspring physiology. However, the effect of both nutrients on fetal development has not been explored. Our objective was to determine the effects of supplementation of these two nutrients during late gestation on fetal growth, DNA methylation, and mRNA expression of genes associated with the inflammatory response, and DNA methylation. Ewes (n = 5/treatment) were fed from day 100 to 145 of gestation one of the following treatments: 1) basal diet (NS) without fatty acids (FS) or methionine (MS) supplementation; 2) FS (10 g/kg Ca salts, source omega-3 PUFA); 3) MS (1 g/kg rumen protected methionine); and 4) FS and MS (FS-MS). On day 145, ewes were euthanized, and data from dams and fetus was recorded. Placenta (cotyledon), fetal liver, and blood samples were collected.

RESULTS

A treatments interaction on fetal liver weight, ewe body weight and body condition score (BCS) was observed; FS-MS were heavier (P <  0.01) than FS and MS, and FS-MS ewes had a better (P = 0.02) BCS than NS. Methionine increased (P = 0.03) ewe plasma glucose concentration. Fetal liver global DNA methylation increased (P <  0.01) in FS and MS. Dietary treatments modify the mRNA relative expression on some of the genes evaluated. In the fetal liver, FS increased (P = 0.04) the mRNA relative expression of arachidonate-5-lipoxygenase-activating-protein and tended to decrease (P = 0.06) methionine-adenosyltransferase-1A. Moreover, MS decreased (P = 0.04) DNA-methyltransferase-1 and tended to decrease (P = 0.08) free-fatty-acid-receptor-1 mRNA relative expression. Furthermore, FS-MS decreased mRNA relative expression of tumor-necrosis-factor-alpha (P = 0.05), peroxisome-proliferator-activated-receptor-delta (P = 0.03) and gamma (P = 0.04), tended to decrease (P ≤ 0.09) interleukin-6, fatty-acid-transport-protein-1, and delta-5-desaturase, and increased adenosylhomocysteinase (P = 0.04) mRNA relative expression. In cotyledon, FS tended to decrease fatty acid binding protein 4 (P = 0.09) mRNA relative expression.

CONCLUSION

Omega-3 PUFA and Met supplementation improves dam's performance in late gestation, which was positively correlated with an increase in offspring's liver development. Moreover, FS-MS decreased mRNA relative expression of proinflammatory cytokines, and lipogenic genes, and increased the expression on an enzyme that has an important role in methylation.

Bovine Stearoyl-CoA Desaturase 1 Promotes Adipogenesis by Activating the PPARγ Receptor

Stearoyl-CoA desaturase 1 (SCD1) is a rate-limiting enzyme that mainly catalyzes the saturated fatty acids (SFAs) into the monounsaturated fatty acids (MUFAs). The expression level of SCD1 is positively correlated with the marbling score. However, the functional mechanism of SCD1 in adipogenesis is still unclear. In this study, we identified SCD1 as highly expressed in subcutaneous and visceral fat, peaking at 2 days after differentiation in bovine stromal vascular fraction (SVF) cells. When the SCD1 was overexpressed in bovine SVF cells, lipid droplets accumulation was increased from 142.46 ± 21.77 to 254.89 ± 11.75 μg/mg (P < 0.01). Further, the expression levels of FABP4, FASN, and ACCα were increased (P < 0.01), while the expression of PPARγ or C/EBPα was not changed at mRNA or protein level (P > 0.05). Dual-luciferase reporter assay showed that the activity of the PPARγ receptor was enhanced by 3.69 times (P < 0.01). Moreover, the contents of palmitoleate (C16:1) and oleate (C18:1) were significantly increased (P < 0.05). Furthermore, 100 μM exogenous oleate increased the lipid accumulation by 22.28 times (P < 0.01). These results suggest that oleate is probably a strong ligand of the PPARγ receptor to enhance adipogenesis.

Metabolomic Analysis of SCD during Goose Follicular Development: Implications for Lipid Metabolism

Stearoyl-CoA desaturase (SCD) is known to be an important rate-limiting enzyme in the production of monounsaturated fatty acids (MUFAs). However, the role of this enzyme in goose follicular development is poorly understood. To investigate the metabolic mechanism of SCD during goose follicular development, we observed its expression patterns in vivo and in vitro using quantitative reverse-transcription (qRT)-PCR. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine a cellular model of SCD function in granulosa cells (GCs) via SCD overexpression and knockdown. qRT-PCR analysis showed that SCD was abundantly expressed in the GC layer, and was upregulated in preovulatory follicles. Peak expression was found in F1 and prehierarchal follicles with diameters of 4–6 mm and 8–10 mm, respectively. We further found that mRNA expression and corresponding enzyme activity occur in a time-dependent oscillation pattern in vitro, beginning on the first day of GC culture. By LC-MS/MS, we identified numerous changes in metabolite activation and developed an overview of multiple metabolic pathways, 10 of which were associated with lipid metabolism and enriched in both the overexpressed and knockdown groups. Finally, we confirmed cholesterol and pantothenol or pantothenate as potential metabolite biomarkers to study SCD-related lipid metabolism in goose GCs.

A comprehensive metabolic profiling of the metabolically healthy obesity phenotype

BACKGROUND

The ever-increasing prevalence of obesity constitutes a major health problem worldwide. A subgroup of obese individuals has been described as "metabolically healthy obese" (MHO). In contrast to metabolically unhealthy obese (MUO), the MHO phenotype has a favorable risk profile. Despite this, the MHO phenotype is still sub-optimally characterized with respect to a comprehensive risk assessment. Our aim was to increase the understanding of metabolic alterations associated with healthy and unhealthy obesity.

METHODS

In this cross-sectional study, men and women (18-70 years) with obesity (body mass index (BMI) ≥ 30 kg/m²) or normal weight (NW) (BMI ≤ 25 kg/m²) were classified with MHO (n = 9), MUO (n = 10) or NW (n = 11) according to weight, lipid profile and glycemic regulation. We characterized individuals by comprehensive metabolic profiling using a commercial available high-throughput proton NMR metabolomics platform. Plasma fatty acid profile, including short chain fatty acids, was measured using gas chromatography.

RESULTS

The concentrations of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) subclasses were overall significantly higher, and high density lipoprotein (HDL) subclasses lower in MUO compared with MHO. VLDL and IDL subclasses were significantly lower and HDL subclasses were higher in NW compared with MHO. The concentration of isoleucine, leucine and valine was significantly higher in MUO compared with MHO, and the concentration phenylalanine was lower in NW subjects compared with MHO. The fatty acid profile in MHO was overall more favorable compared with MUO.

CONCLUSIONS

Comprehensive metabolic profiling supports that MHO subjects have intermediate-stage cardiovascular disease risk marker profile compared with NW and MUO subjects.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01034436, Fatty acid quality and overweight (FO-study).

Supplementation with eicosapentaenoic and docosahexaenoic acids in late gestation in ewes changes adipose tissue gene expression in the ewe and growth and plasma concentration of ghrelin in the offspring1

Omega-3 long chain fatty acids have a positive impact on production. When consumed during late gestation, it might have fetal programming effects on the fetus, which will have lifelong impacts on development and production. The objectives of the present study were to evaluate the effect of increasing doses of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the diet of ewes in the last third of gestation on their body weight (BW), subcutaneous adipose tissue relative mRNA abundance of genes associated with adipose tissue metabolism, and growth performance and plasma metabolites and hormones of their offspring during the finishing phase. Ewes (n = 72) were blocked by BW and allotted to pens (8 per treatment) with 3 ewes per pen. Ewes were supplemented with an EPA and DHA source (Strata G113) at concentrations of 0, 1, or 2% of dry matter intake during the last 50 d of gestation. At lambing, all ewes were penned together and offered the same diet. After weaning at 60 d of age, lambs were blocked by BW and sex and fed for 56 d. All lambs were fed the same pellet diet (61.09% ground corn, 24.08% soy hulls, 11.09% soybean meal, 1.48% Ca salt of palm oil, and 2.26% mixed mineral vitamin), and were weighed every 14 d until the end of the trial. Blood samples were collected on the weight sampling days. Dry matter intake and refusals were weighed daily. Data were analyzed as a randomized complete block design with repeated measurements (SAS 9.4). Polynomial contrast (linear-L and quadratic-Q) was used for mean separation. There were no differences in ewe body condition score, milk production, milk fat, or milk protein, but there was a trend for increased (L, P = 0.06) lactose concentration, and also differences in DGAT1 (L, P = 0.04), Δ5-desaturase (Q, P = 0.06) and Δ6-desaturase (Q, P = 0.07), PPARα (Q, P = 0.03), ELOVL2 and 5 (Q, P < 0.07), FABP4 (Q, P = 0.04), FATP1 (Q, P = 0.06), leptin (Q, P = 0.02), and resistin (L, P = 0.05). Feeding pregnant ewes an increased amount of EPA and DHA in late gestation increased final BW (L, P = 0.01), ADG (L, P = 0.04; Q, P = 0.01), DMI (Q, P ≤ 0.01), plasma glucose concentration (L, P = 0.04), and trended to decrease ghrelin concentrations (L, P = 0.07) in offspring during the finishing period. Dam supplementation did not affect G:F, nor plasma NEFA concentration (P ≥ 0.53) of lambs. Therefore, increasing supplementation of EPA and DHA in pregnant ewes has an impact on offspring performance, increasing DMI, ADG, and BW.

SCD1 activation impedes foam cell formation by inducing lipophagy in oxLDL-treated human vascular smooth muscle cells

The formation of fat-laden foam cells, which contributes to the fatty streaks in the plaques of atheromas, is an important process in atherosclerosis. Vascular smooth muscle cells (VSMCs) are a critical origin of foam cells. However, the mechanisms that underlie VSMC foam cell formation are not yet completely understood. Here, we demonstrated that oxidized low-density lipoprotein (oxLDL) inhibited lipophagy by suppressing lipid droplet (LD)-lysosome fusion and increased VSMC foam cell formation. Moreover, although oxLDL treatment inhibited lysosomal biogenesis, it had no significant effect on lysosomal proteolysis and lysosomal pH. Notably, through TMT-based quantitative proteomic analysis and database searching, 94 differentially expressed proteins were identified, of which 54 were increased and 40 were decreased in the oxLDL group compared with those in the control group. Subsequently, SCD1, a protein of interest, was further investigated. SCD1 levels in the VSMCs were down-regulated by exposure to oxLDL in a time-dependent manner and the interaction between SCD1 and LDs was also disrupted by oxLDL. Importantly, SCD1 overexpression enhanced LD-lysosome fusion, increased lysosomal biogenesis and inhibited VSMC foam cell formation by activating TFEB nuclear translocation and its reporter activity. Modulation of the SCD1/TFEB-mediated lipophagy machinery may offer novel therapeutic approaches for the treatment of atherosclerosis.