Polyunsaturated Fatty Acids Regulation Research Articles

Ancestry-driven metabolite variation provides insights into disease states in admixed populations

BackgroundMetabolic pathways are related to physiological functions and disease states and are influenced by genetic variation and environmental factors. Hispanics/Latino individuals have ancestry-derived genomic regions (local ancestry) from their recent admixture that have been less characterized for associations with metabolite abundance and disease risk.MethodsWe performed admixture mapping of 640 circulating metabolites in 3887 Hispanic/Latino individuals from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Metabolites were quantified in fasting serum through non-targeted mass spectrometry (MS) analysis using ultra-performance liquid chromatography-MS/MS. Replication was performed in 1856 nonoverlapping HCHS/SOL participants with metabolomic data.ResultsBy leveraging local ancestry, this study identified significant ancestry-enriched associations for 78 circulating metabolites at 484 independent regions, including 116 novel metabolite-genomic region associations that replicated in an independent sample. Among the main findings, we identified Native American enriched genomic regions at chromosomes 11 and 15, mapping to FADS1/FADS2 and LIPC, respectively, associated with reduced long-chain polyunsaturated fatty acid metabolites implicated in metabolic and inflammatory pathways. An African-derived genomic region at chromosome 2 was associated with N-acetylated amino acid metabolites. This region, mapped to ALMS1, is associated with chronic kidney disease, a disease that disproportionately burdens individuals of African descent.ConclusionsOur findings provide important insights into differences in metabolite quantities related to ancestry in admixed populations including metabolites related to regulation of lipid polyunsaturated fatty acids and N-acetylated amino acids, which may have implications for common diseases in populations.

Milk fat as a source of bioactive compounds

Milk fat as a source of bioactive compounds

Hepatic Levels of DHA-Containing Phospholipids Instruct SREBP1-Mediated Synthesis and Systemic Delivery of Polyunsaturated Fatty Acids.

SummaryPolyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA) and arachidonic acid (ARA), play fundamental roles in mammalian physiology. Although PUFA imbalance causes various disorders, mechanisms of the regulation of their systemic levels are poorly understood. Here, we report that hepatic DHA-containing phospholipids (DHA-PLs) determine the systemic levels of PUFAs through the SREBP1-mediated transcriptional program. We demonstrated that liver-specific deletion of Agpat3 leads to a decrease of DHA-PLs and a compensatory increase of ARA-PLs not only in the liver but also in other tissues including the brain. Together with recent findings that plasma lysophosphatidylcholine (lysoPC) is the major source of brain DHA, our results indicate that hepatic AGPAT3 contributes to brain DHA accumulation by supplying DHA-PLs as precursors of DHA-lysoPC. Furthermore, dietary fish oil-mediated suppression of hepatic PUFA biosynthetic program was blunted in liver-specific Agpat3 deletion. Our findings highlight the central role of hepatic DHA-PLs as the molecular rheostat for systemic homeostasis of PUFAs.

Уміст жирних кислот у м’язовій тканині свиней за застосування кормових добавок LG-MAX і Сел-Плекс

Уміст жирних кислот у м’язовій тканині свиней за застосування кормових добавок LG-MAX і Сел-Плекс

Integrated metabolomic and transcriptomic analyses identify critical genes in eicosapentaenoic acid biosynthesis and metabolism in the sea urchin Strongylocentrotus intermedius

Gonads are the only edible part of the sea urchin and have great potential as a health-promoting food for human consumption. Polyunsaturated fatty acids (PUFAs) are important necessary nutrients that determine not only the nutritional value of sea urchins but guarantee their normal growth and reproduction. However, the information on the molecular mechanisms of PUFA biosynthesis and metabolism in this species remains elusive. In this study, we used Strongylocentrotus intermedius as our model species and conducted integrated metabolomic and transcriptomic analyses of potentially critical genes involved in PUFA biosynthesis and metabolism during gonad growth and development, mainly focusing on eicosapentaenoic acid (EPA). We found six differentially accumulated metabolites associated with PUFA in the metabolomic analysis. More differentially expressed genes (DEGs) were related to PUFA in testis than ovary (1823 DEGs in testis and 1499 DEGs in ovary). We verified 12 DEGs by RNA-Seq results and found that Aldh7a1, Ecm3, Fads2, and Hsd17b12 genes had similar expression patterns in EPA concentration during gonad growth and development. In contrast, the other DEGs were downregulated and we inferred that EPA or PUFA may be metabolized as energy during certain periods. Our metabolic and genetic data will facilitate a better understanding of PUFA regulation networks during gonad growth and development in S. intermedius.

Polyunsaturated Fatty Acid Regulation of the Acid-Sensing Ion Channels

The Acid Sensing Ion Channels (ASICS) are proton activated, voltage-insensitive, sodium channels found throughout the peripheral and central nervous systems. Tissue acidosis can occur due to injury, ischemia, and inflammation which can lead to ASIC activation. Pain that occurs with several of these conditions, including ischemia and inflammation, has previously been linked to the activation of ASICs. In addition, ASICs have been shown to be able to sense several pro-inflammatory agents that are increased under these pathophysiological conditions. The polyunsaturated fatty acid (PUFA), Arachidonic Acid, is one such molecule that potentiates ASIC isoforms 1a, 2 and 3 at concentrations reached during inflammation. Interestingly, several other PUFAs have been shown to similarly potentiate ASIC1a. However, no study has yet to elucidate the mechanism of PUFA potentiation, nor has there been a thorough investigation of the how different properties of PUFAs modulate their effect on ASICs. Here we characterized how PUFA chain length, number of double bonds, location of double bonds and head group relate to potentiation of several ASIC isoforms. First, we demonstrate that PUFAs potentiates ASICs via an alkaline shift in the pH dependence of activation. In contrast to a previous finding, we show that the head group is critical for ASIC regulation by PUFAs. PUFAs with a negatively charged head group, like Arachidonoyl Glycine, dramatically shift the pH dependence of ASIC activation while uncharged head groups like Arachidonic Acid methyl ester have no effect on channel function. In addition, we show that the position of double bonds in the fatty acid tail are important for ASIC regulation as well. Finally, mutagenesis is used to localize possible PUFA interaction sites with ASICs.

Imbalance of n6/n3 fatty acids in the training period and after competition in cross-country Skiers

The aim of the study was to investigate the level of essential polyunsaturated fatty acids (PUFAs) in athletes into the training period and after endurance race (n=15 high-trained male cross-country skiers, real members of national skiing team). The PUFAs in plasma was determined by the gas-liquid chromatography method. Results demonstrate a deficiency of plasma level of the n-3 PUFA of the almost all skiers during the training period. Competition activity modified the essential PUFA profile in blood across more twice increase of the n-3 docosahexaenoic acids (DHA) (p=0.112) and n-3 alpha-linolenic (ALA) (p=0.048) levels and decrease n-6 PUFA relative to baselines, which expressed in a decrease in n6/n3 ratio (p=0.017). Relationships between n-3/n-6 ratio and base heart rate, diastolic pressure and Maximal oxygen uptake, show on the significant role essential PUFAs in regulation of the cardiovascular system in cross-country skiers.

Imbalance of n6/n3 fatty acids in the training period and after competition in cross-country Skiers

The aim of the study was to investigate the level of essential polyunsaturated fatty acids (PUFAs) in athletes into the training period and after endurance race (n=15 high-trained male cross-country skiers, real members of national skiing team). The PUFAs in plasma was determined by the gas-liquid chromatography method. Results demonstrate a deficiency of plasma level of the n-3 PUFA of the almost all skiers during the training period. Competition activity modified the essential PUFA profile in blood across more twice increase of the n-3 docosahexaenoic acids (DHA) (p=0.112) and n-3 alpha-linolenic (ALA) (p=0.048) levels and decrease n-6 PUFA relative to baselines, which expressed in a decrease in n6/n3 ratio (p=0.017). Relationships between n3/n-6 ratio and base heart rate, diastolic pressure and Maximal oxygen uptake, show on the significant role essential PUFAs in regulation of the cardiovascular system in cross-country skiers.

CRISPR/Cas9-mediated ablation of elovl2 in Atlantic salmon (Salmo salar L.) inhibits elongation of polyunsaturated fatty acids and induces Srebp-1 and target genes

Atlantic salmon can synthesize polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (20:5n-3), arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3) via activities of very long chain fatty acyl elongases (Elovls) and fatty acyl desaturases (Fads), albeit to a limited degree. Understanding molecular mechanisms of PUFA biosynthesis and regulation is a pre-requisite for sustainable use of vegetable oils in aquafeeds as current sources of fish oils are unable to meet increasing demands for omega-3 PUFAs. By generating CRISPR-mediated elovl2 partial knockout (KO), we have shown that elovl2 is crucial for multi-tissue synthesis of 22:6n-3 in vivo and that endogenously synthesized PUFAs are important for transcriptional regulation of lipogenic genes in Atlantic salmon. The elovl2-KOs showed reduced levels of 22:6n-3 and accumulation of 20:5n-3 and docosapentaenoic acid (22:5n-3) in the liver, brain and white muscle, suggesting inhibition of elongation. Additionally, elovl2-KO salmon showed accumulation of 20:4n-6 in brain and white muscle. The impaired synthesis of 22:6n-3 induced hepatic expression of sterol regulatory element binding protein-1 (srebp-1), fatty acid synthase-b, Δ6fad-a, Δ5fad and elovl5. Our study demonstrates key roles of elovl2 at two penultimate steps of PUFA synthesis in vivo and suggests Srebp-1 as a main regulator of endogenous PUFA synthesis in Atlantic salmon.

Sterol regulatory element binding protein-1: Molecular cloning, tissue distribution and gene expression level in response to nutritional regulation in mud crab, Scylla paramamosain

In the present study, SREBP-1 cDNA was cloned from the hepatopancreas of mud crab (Scylla paramamosain) and characterized by performing rapid-amplification of cDNA ends. The 3361bp long full-length cDNA encodes a polypeptide with 1039 amino acids. Tissue distribution analysis revealed that SREBP-1 transcripts were widely distributed in various organs, with higher mRNA levels in the eyestalk and cranial ganglia. Further, expression level of SREBP-1 mRNA were up-regulated in proportion to the replacement of dietary fish oil (FO) with soybean oil (SO). These results may contribute to better understanding of the long-chain polyunsaturated fatty acids (LC-PUFA) biosynthetic pathway and regulation mechanism in mud crab.

Cloning, tissue distribution and nutritional regulation of a fatty acyl Elovl4-like elongase in mud crab, Scylla paramamosain (Estampador, 1949).

In this report, the full-length cDNA of fatty acyl Elovl4-like elongase was cloned from the hepatopancreas of Scylla paramamosain by rapid-amplification of cDNA ends (RACE). To the best of our knowledge, this is the first report of Elovl4-like elongase in crustaceans. The full-length cDNA of Elovl4-like was 1119bp, which included a 5'-terminal untranslated region (UTR) of 58bp, a 3'-terminal UTR of 44bp and an open reading frame (ORF) of 1017bp encoding a polypeptide of 338 amino acids. Tissue distribution analysis revealed that Elovl4-like transcripts are widely distributed in various organs, with high mRNA levels in the hepatopancreas and cranial ganglia. Further, Elovl4-like transcriptional levels in hepatopancreas were up-regulated in proportion to the replacement of dietary fish oil (FO) with soybean oil (SO). The result showed that Elovl4-like transcripts increased about 0.83 and 1.12-fold respectively when SO constituted 80% and 100% of total oil (P<0.05). These results may contribute to better understanding of the long-chain polyunsaturated fatty acids (LC-PUFA) biosynthetic pathway and regulation mechanism in this species.

PPARγ regulates exocrine pancreas lipase

AimPancreatic lipase (triacylglycerol lipase EC 3.1.1.3) is an essential enzyme in hydrolysis of dietary fat. Dietary fat, especially polyunsaturated fatty acids (PUFA), regulate pancreatic lipase (PNLIP); however, the molecular mechanism underlying this regulation is mostly unknown. As PUFA are known to regulate expression of proliferator-activated receptor gamma (PPARγ), and as we identified in-silico putative PPARγ binding sites within the putative PNLIP promoter sequence, we hypothesized that PUFA regulation of PNLIP might be mediated by PPARγ. Materials and methodsWe used in silico bioinformatics tools, reporter luciferase assay, PPARγ agonists and antagonists, PPARγ overexpression in exocrine pancreas AR42J and primary cells to study PPARγ regulation of PNLIP. ResultsUsing in silico bioinformatics tools we mapped PPARγ binding sites (PPRE) to the putative promoter region of PNLIP. Reporter luciferase assay in AR42J rat exocrine pancreas acinar cells transfected with various constructs of the putative PNLIP promoter showed that PNLIP transcription is significantly enhanced by PPARγ dose-dependently, reaching maximal levels with multi PPRE sites. This effect was significantly augmented in the presence of PPARγ agonists and reduced by PPARγ antagonists or mutagenesis abrogating PPRE sites. Over-expression of PPARγ significantly elevated PNLIP transcript and protein levels in AR42J cells and in primary pancreas cells. Moreover, PNLIP expression was up-regulated by PPARγ agonists (pioglitazone and 15dPGJ2) and significantly down-regulated by PPARγ antagonists in non-transfected rat exocrine pancreas AR42J cell line cells. ConclusionPPARγ transcriptionally regulates PNLIP gene expression. This transcript regulation resolves part of the missing link between dietary PUFA direct regulation of PNLIP.

Alternative splicing generates novel Fads3 transcript in mice.

Fads3 is the third member of the fatty acid desaturase gene cluster; with at least eight evolutionarily conserved alternative transcripts (AT), having no clearly established function as are known for FADS2 and FADS1. Here we present identification of a novel Fads3 transcript in mice (Fads3AT9), characterize Fads3AT9 expression in mouse tissues and evaluate correlations with metabolite profiles. Total RNA obtained from mouse tissues is reverse-transcribed into cDNA and used as template for PCR reactions. Tissue fatty acids were extracted and quantified by gas chromatography. Sequencing analysis revealed complete absence of exon 2 resulting in an open reading frame of 1239bp, encoding a putative protein of 412 aa with loss of 37 aa compared to classical Fads3 (Fads3CS). FADS3AT9 retains all the conserved regions characteristic of front end desaturase (cytochrome b5 domain and three histidine repeats). Both Fads3CS and Fads3AT9 are ubiquitously expressed in 11 mouse tissues. Fads3AT9 abundance was greater than Fads3CS in pancreas, liver, spleen, brown adipose tissue and thymus. Fads3CS expression is low in pancreas while Fads3AT9 is over ten-fold greater abundance. The eicosanoid precursor fatty acid 20:4n-6, the immediate desaturation product of the Fads1 coded Δ5-desaturase, was highest in pancreas where Fads3CS is low. Changes in expression patterns and fatty acid profiles suggest that Fads3AT9 may play a role in the regulation and/or biosynthesis of long chain polyunsaturated fatty acids from precursors.

Fatty Acid Desaturases, Polyunsaturated Fatty Acid Regulation, and Biotechnological Advances.

Polyunsaturated fatty acids (PUFAs) are considered to be critical nutrients to regulate human health and development, and numerous fatty acid desaturases play key roles in synthesizing PUFAs. Given the lack of delta-12 and -15 desaturases and the low levels of conversion to PUFAs, humans must consume some omega-3 and omega-6 fatty acids in their diet. Many studies on fatty acid desaturases as well as PUFAs have shown that fatty acid desaturase genes are closely related to different human physiological conditions. Since the first front-end desaturases from cyanobacteria were cloned, numerous desaturase genes have been identified and animals and plants have been genetically engineered to produce PUFAs such as eicosapentaenoic acid and docosahexaenoic acid. Recently, a biotechnological approach has been used to develop clinical treatments for human physiological conditions, including cancers and neurogenetic disorders. Thus, understanding the functions and regulation of PUFAs associated with human health and development by using biotechnology may facilitate the engineering of more advanced PUFA production and provide new insights into the complexity of fatty acid metabolism.

Metabolic and molecular regulation of dietary polyunsaturated fatty acids on prostate cancer.

The aim of this study is to investigate the role of n-3 and n-9 fatty acids in crucial processes involved in prostate cancer cell growth through a large-scale proteomic analysis. We used a label-free protein quantification method to profile global protein expression of fish oil and oleic acid treated PCa cells and validated a panel of differentially expressed proteins by either Western blot or multiple reaction monitoring. Bioinformatic analysis was also performed to uncover the pathways involved in fatty acid metabolism. Fish oil, not oleic acid, suppresses prostate cancer cell viability. Assessment of fatty acid synthesis pathway activity also shows that oleic acid is a more potent inhibitor than fish oil on de novo fatty acid synthesis. Although fatty acid synthase activity decreases with fish oil treatment, the inhibition of its activity occurs over time while reduction in viability occurs within 24 h. Bioinformatic analysis revealed the pathways altered by these fatty acid treatments. This study suggests that suppression of cell viability by fish oil is independent of fatty acid synthase and fish oil regulates prostate cancer cells through activation of other pathways depending upon length of exposure to fish oil.

Reciprocal Modulation of Surface Expression of Annexin A2 in a Human Umbilical Vein Endothelial Cell-Derived Cell Line by Eicosapentaenoic Acid and Docosahexaenoic Acid

BackgroundAnnexin A2 (ANXA2), a member of the annexin family of cytosolic Ca2+-binding proteins, plays a pivotal role in vascular biology. Small amounts of this protein and S100A10 protein are exposed on the surface of endothelial cells (ECs). They control fibrinolysis by recruiting tissue-type and urokinase-type plasminogen activators from the plasma. Nutritional studies indicate that two major long-chain polyunsaturated fatty acids (PUFAs), i.e., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), provide benefits for EC functions. The effects of EPA and DHA on the plasminogen/plasmin system have not been characterized.Methodology/Principal FindingsProteomic analysis of a cultured human umbilical vein EC-derived cell line, HUV-EC-C, showed that cell-associated ANXA2 decreased with EPA treatment and increased with DHA. A small fraction of ANXA2 was bound to the cell surface, which was also affected by these PUFAs following the same trends. Cell surface expression was negatively regulated by protein kinase C (PKC) α-mediated Ser-phosphorylation, which was up- and down-regulated by EPA and DHA, respectively. These PUFAs differentially affected a small fraction of caveolae/rafts-associated ANXA2. In addition to chymotrypsin-like activity in the serum, newly activated plasmin cleaved the ANXA2 on the cell surface at distinct sites in the N-terminal sequence. ANXA2 also bound to membranes released in the medium, which was similarly processed by these proteases. Both the PUFAs did not directly affect the release.Conclusion/SignificanceThese results suggest that EPA and DHA reciprocally control cell surface location of ANXA2. Moreover, cleavage of this protein by plasmin likely resulted in autodigestion of the platform for formation of this protease. In conjunction with termination of the proteolysis by rapid inactivation of plasmin by α-2-antiplasmin and other polypeptide inhibitors, this feedback mechanism may emphasize the benefits of these PUFA in regulation of the initiation of fibrinolysis on the surface of ECs.

Retinoid X receptor activation is essential for docosahexaenoic acid protection of retina photoreceptors

We have established that docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in the retina, promotes survival of rat retina photoreceptors during early development in vitro and upon oxidative stress by activating the ERK/MAPK signaling pathway. Here we have investigated whether DHA turns on this pathway through activation of retinoid X receptors (RXRs) or by inducing tyrosine kinase (Trk) receptor activation. We also evaluated whether DHA release from phospholipids was required for its protective effect. Addition of RXR antagonists (HX531, PA452) to rat retinal neuronal cultures inhibited DHA protection during early development in vitro and upon oxidative stress induced with Paraquat or H2O2. In contrast, the Trk inhibitor K252a did not affect DHA prevention of photoreceptor apoptosis. These results imply that activation of RXRs was required for DHA protection whereas Trk receptors were not involved in this protection. Pretreatment with 4-bromoenol lactone, a phospholipase A2 inhibitor, blocked DHA prevention of oxidative stress-induced apoptosis of photoreceptors. It is noteworthy that RXR agonists (HX630, PA024) also rescued photoreceptors from H2O2-induced apoptosis. These results provide the first evidence that activation of RXRs prevents photoreceptor apoptosis and suggest that DHA is first released from phospholipids and then activates RXRs to promote the survival of photoreceptors.

Membrane lipid raft organization is uniquely modified by n-3 polyunsaturated fatty acids

Fish oil, enriched in bioactive n-3 polyunsaturated fatty acids (PUFA), has been shown to play a role in prevention of colon cancer. The effects of n-3 PUFA are pleiotropic and multifaceted, resulting in an incomplete understanding of their molecular mechanisms of action. Here, we focus on a highly conserved mechanism of n-3 PUFA, which is the alteration of the organization of the plasma membrane. We highlight recent work demonstrating that enrichment of n-3 PUFA in the plasma membrane alters the lateral organization of membrane signaling assemblies (i.e. lipid rafts). This mechanism is central for n-3 PUFA regulation of downstream signaling, T-cell activation, transcriptional activation, and cytokine secretion. We conclude that these studies provide strong evidence for a predominant mechanism by which n-3 PUFA function in colon cancer prevention.

Bimodal Distribution of Polyunsaturated Fatty Acids in Schizophrenia Suggests Two Endophenotypes of the Disorder

There is conflicting evidence of whether polyunsaturated fatty acids (PUFA) in red blood cells are bimodally distributed in schizophrenia. The purpose of this study was to examine the distribution of PUFA, as well as its links to plausible causal factors. A 16-week cohort study and a case-control study as part of a randomized controlled trial. Ninety-nine patients with DSM-IV schizophrenia, schizoaffective disorder, or schizophreniform disorder, aged 18 to 39, were consecutively included at admission to psychiatric departments of nine Norwegian hospitals. Fatty acids were measured in 97 of these patients and in 20 healthy control subjects. The primary outcome measure was the bimodality test statistic T, assessed by a χ(2) test of the likelihood of one or two normal distributions of PUFA. At baseline, levels of polyunsaturated fatty acids were highly significantly bimodally distributed among patients. One third of patients constituted a group (low PUFA) who had PUFA levels at one fifth (p < .001) of those in high PUFA patients and healthy control subjects, which did not differ. Bimodality was mainly accounted for by docosahexaenoic acid and arachidonic acid. Bimodality was confirmed after 16 weeks. α-tocopherol was a robust predictor of PUFA at both occasions. Desaturase and elongase indexes differed between PUFA groups. Smoking, gender, antipsychotic medication, and dietary factors did not explain the bimodal distribution. Red blood cell PUFA were bimodally distributed among acutely ill patients with schizophrenia and schizoaffective disorder. Endogenous deficiencies of redox regulation or synthesis of long-chain PUFA in the low PUFA group may explain our findings.

Increased preconception omega-3 polyunsaturated fatty acid intake improves embryo morphology

The association between preconception dietary intake of the polyunsaturated fatty acids (LC-PUFAs) omega-6 and omega-3 and the E(2) levels and IVF/intracytoplasmic sperm injection (ICSI) outcome were investigated in women in a prospective study. It revealed that high intakes of omega-3 LC-PUFA alpha-linolenic acid increase baseline E(2), high intakes of eicosapentaenoic acid and docosahexaenoic acid reduce E(2) response and the number of follicles after ovarian stimulation, and total omega-3 intake, in particular alpha-linolenic acid and docosahexaenoic acid, improve embryo morphology.