Showing papers on "ATP citrate lyase published in 2016"
TL;DR: Short-term fasting or treatment with several chemically unrelated autophagy-inducing CRMs, including hydroxycitrate and spermidine, improved the inhibition of tumor growth by chemotherapy in vivo and improved anticancer immunosurveillance and reducing tumor mass.
382 citations
TL;DR: It is shown that, upon genetic deletion of Acly, the gene coding for ATP-citrate lyase (ACLY), cells remain viable and proliferate, although at an impaired rate, and engagement of acetate metabolism is a crucial, although partial, mechanism of compensation for ACLY deficiency.
266 citations
TL;DR: ETC-1002 is a prodrug that requires activation by very long-chain acyl-CoA synthetase-1 (ACSVL1) to modulate both targets, and that inhibition of ACL leads to LDL receptor upregulation, decreased LDL-C and attenuation of atherosclerosis, independently of AMPK.
Abstract: Despite widespread use of statins to reduce low-density lipoprotein cholesterol (LDL-C) and associated atherosclerotic cardiovascular risk, many patients do not achieve sufficient LDL-C lowering due to muscle-related side effects, indicating novel treatment strategies are required. Bempedoic acid (ETC-1002) is a small molecule intended to lower LDL-C in hypercholesterolemic patients, and has been previously shown to modulate both ATP-citrate lyase (ACL) and AMP-activated protein kinase (AMPK) activity in rodents. However, its mechanism for LDL-C lowering, efficacy in models of atherosclerosis and relevance in humans are unknown. Here we show that ETC-1002 is a prodrug that requires activation by very long-chain acyl-CoA synthetase-1 (ACSVL1) to modulate both targets, and that inhibition of ACL leads to LDL receptor upregulation, decreased LDL-C and attenuation of atherosclerosis, independently of AMPK. Furthermore, we demonstrate that the absence of ACSVL1 in skeletal muscle provides a mechanistic basis for ETC-1002 to potentially avoid the myotoxicity associated with statin therapy.
265 citations
TL;DR: The results demonstrate that increased systemic acetate concentrations are functionally integrated by CD8(+) T cells and translate into increased glycolytic and functional capacity, and the immune system thus directly relates systemic metabolism with immune alertness.
238 citations
TL;DR: It is found that increased amounts of the oncometabolite d-2-hydroxyglutarate (D2-HG), produced by IDH2 mutant leukemic cells, cause contractile dysfunction in the heart.
Abstract: Hematologic malignancies are frequently associated with cardiac pathologies. Mutations of isocitrate dehydrogenase 1 and 2 (IDH1/2) occur in a subset of acute myeloid leukemia patients, causing metabolic and epigenetic derangements. We have now discovered that altered metabolism in leukemic cells has a profound effect on cardiac metabolism. Combining mathematical modeling and in vivo as well as ex vivo studies, we found that increased amounts of the oncometabolite d-2-hydroxyglutarate (D2-HG), produced by IDH2 mutant leukemic cells, cause contractile dysfunction in the heart. This contractile dysfunction is associated with impaired oxidative decarboxylation of α-ketoglutarate, a redirection of Krebs cycle intermediates, and increased ATP citrate lyase (ACL) activity. Increased availability of D2-HG also leads to altered histone methylation and acetylation in the heart. We propose that D2-HG promotes cardiac dysfunction by impairing α-ketoglutarate dehydrogenase and induces histone modifications in an ACL-dependent manner. Collectively, our results highlight the impact of cancer cell metabolism on function and metabolism of the heart.
96 citations
TL;DR: This work identifies ubiquitin-specific peptidase 13 (USP13) as a master regulator that drives ovarian cancer metabolism and deubiquitinates and thus upregulates ATP citrate lyase and oxoglutarate dehydrogenase, two key enzymes that determine mitochondrial respiration, glutaminolysis and fatty acid synthesis.
Abstract: Dysregulated energetic metabolism has been recently identified as a hallmark of cancer. Although mutations in metabolic enzymes hardwire metabolism to tumourigenesis, they are relatively infrequent in ovarian cancer. More often, cancer metabolism is re-engineered by altered abundance and activity of the metabolic enzymes. Here we identify ubiquitin-specific peptidase 13 (USP13) as a master regulator that drives ovarian cancer metabolism. USP13 specifically deubiquitinates and thus upregulates ATP citrate lyase and oxoglutarate dehydrogenase, two key enzymes that determine mitochondrial respiration, glutaminolysis and fatty acid synthesis. The USP13 gene is co-amplified with PIK3CA in 29.3% of high-grade serous ovarian cancers and its overexpression is significantly associated with poor clinical outcome. Inhibiting USP13 remarkably suppresses ovarian tumour progression and sensitizes tumour cells to the treatment of PI3K/AKT inhibitor. Our results reveal an important metabolism-centric role of USP13, which may lead to potential therapeutics targeting USP13 in ovarian cancers.
80 citations
TL;DR: This work demonstrated that ALE may be a promising tool in modifying microalga strains by applying high oxygen as a selection pressure to improve the production capacity of Schizochytrium sp.
74 citations
TL;DR: The design of a large phase 3 program is being considered to gain more information on efficacy and safety of ETC-1002 in combination with statins and when added to ezetimibe in statin-intolerant patients.
Abstract: Bempedoic acid (ETC-1002), a novel therapeutic approach for low-density lipoprotein cholesterol (LDL-C) lowering, inhibits ATP citrate lyase (ACL), an enzyme involved in fatty acid and cholesterol synthesis. Although rodent studies suggested potential effects of ACL inhibition on both fatty acid and cholesterol synthesis, studies in humans show an effect only on cholesterol synthesis. In phase 2 studies, ETC-1002 reduced LDL-C as monotherapy, combined with ezetimibe, and added to statin therapy, with LDL-C lowering most pronounced when ETC-1002 was combined with ezetimibe in patients who cannot tolerate statins. Whether clinically relevant favorable effects on other cardiometabolic risk factors such as hyperglycemia and insulin resistance occur in humans is unknown and requires further investigation. Promising phase 2 results have led to the design of a large phase 3 program to gain more information on efficacy and safety of ETC-1002 in combination with statins and when added to ezetimibe in statin-intolerant patients.
71 citations
TL;DR: A retrovirus-based protein complementation assay is used to find LMW-E binding proteins in breast cancer, identifying ATP-citrate lyase (ACLY), an enzyme in the de novo lipogenesis pathway, as a novel L MW-E-interacting protein in the cytoplasm as well as establishing a novel relationship between low molecular weight isoforms of cyclin E and aberrant lipid metabolism pathways in Breast cancer tumorigenesis.
Abstract: Cyclin E is altered in nearly a third of invasive breast cancers where it is a powerful independent predictor of survival in women with stage I-III disease. Full-length cyclin E is posttranslationally cleaved into low molecular weight (LMW-E) isoforms, which are tumor-specific and accumulate in the cytoplasm because they lack a nuclear localization sequence. We hypothesized that aberrant localization of cytosolic LMW-E isoforms alters target binding and activation ultimately contributing to LMW-E-induced tumorigenicity. To address this hypothesis, we used a retrovirus-based protein complementation assay to find LMW-E binding proteins in breast cancer, identifying ATP-citrate lyase (ACLY), an enzyme in the de novo lipogenesis pathway, as a novel LMW-E-interacting protein in the cytoplasm. LMW-E upregulated ACLY enzymatic activity, subsequently increasing lipid droplet formation, thereby providing cells with essential building blocks to support growth. ACLY was also required for LMW-E-mediated transformation, migration, and invasion of breast cancer cells in vitro along with tumor growth in vivo In clinical specimens of breast cancer, the absence of LMW-E and low expression of adipophilin (PLIN2), a marker of lipid droplet formation, associated with favorable prognosis, whereas overexpression of both proteins correlated with a markedly worse prognosis. Taken together, our findings establish a novel relationship between LMW-E isoforms of cyclin E and aberrant lipid metabolism pathways in breast cancer tumorigenesis, warranting further investigation in additional malignancies exhibiting their expression. Cancer Res; 76(8); 2406-18. ©2016 AACR.
65 citations
TL;DR: This study incorporated an alternative mode of acetyl-CoA biosynthesis mediated by ATP citrate lyase (ACL) that may obviate such constraints in Saccharomyces cerevisiae and significantly improved mevalonate production.
Abstract: With increasing concern about the environmental impact of a petroleum based economy, focus has shifted towards greener production strategies including metabolic engineering of microbes for the conversion of plant-based feedstocks to second generation biofuels and industrial chemicals. Saccharomyces cerevisiae is an attractive host for this purpose as it has been extensively engineered for production of various fuels and chemicals. Many of the target molecules are derived from the central metabolite and molecular building block, acetyl-CoA. To date, it has been difficult to engineer S. cerevisiae to continuously convert sugars present in biomass-based feedstocks to acetyl-CoA derived products due to intrinsic physiological constraints—in respiring cells, the precursor pyruvate is directed away from the endogenous cytosolic acetyl-CoA biosynthesis pathway towards the mitochondria, and in fermenting cells pyruvate is directed towards the byproduct ethanol. In this study we incorporated an alternative mode of acetyl-CoA biosynthesis mediated by ATP citrate lyase (ACL) that may obviate such constraints. We characterized the activity of several heterologously expressed ACLs in crude cell lysates, and found that ACL from Aspergillus nidulans demonstrated the highest activity. We employed a push/pull strategy to shunt citrate towards ACL by deletion of the mitochondrial NAD+-dependent isocitrate dehydrogenase (IDH1) and engineering higher flux through the upper mevalonate pathway. We demonstrated that combining the two modifications increases accumulation of mevalonate pathway intermediates, and that both modifications are required to substantially increase production. Finally, we incorporated a block strategy by replacing the native ERG12 (mevalonate kinase) promoter with the copper-repressible CTR3 promoter to maximize accumulation of the commercially important molecule mevalonate. By combining the push/pull/block strategies, we significantly improved mevalonate production. We anticipate that this strategy can be used to improve the efficiency with which industrial strains of S. cerevisiae convert feedstocks to acetyl-CoA derived fuels and chemicals.
57 citations
TL;DR: In this article, the Warburg effect has been used as an indicator of cancer aggressiveness and/or biomarker for response to therapy in human prostate cancer, where citrate levels could be monitored as a biomarker of tumor aggressiveness.
TL;DR: It is suggested that the reduction in proton pump activity is the key factor for the low citrate accumulation and the comprehensive metabolite alterations as well in ‘HAL’.
Abstract: 'Hong Anliu' (HAL, Citrus sinensis cv. Hong Anliu) is a bud mutant of 'Anliu' (AL), characterized by a comprehensive metabolite alteration, such as lower accumulation of citrate, high accumulation of lycopene and soluble sugars in fruit juice sacs. Due to carboxylic acid metabolism connects other metabolite biosynthesis and/or catabolism networks, we therefore focused analyzing citrate accumulation-related gene expression profiles and/or enzyme activities, along with metabolic fingerprinting between 'HAL' and 'AL'. Compared with 'AL', the transcript levels of citrate biosynthesis- and utilization-related genes and/or the activities of their respective enzymes such as citrate synthase, cytosol aconitase and ATP-citrate lyase were significantly higher in 'HAL'. Nevertheless, the mitochondrial aconitase activity, the gene transcript levels of proton pumps, including vacuolar H(+)-ATPase, vacuolar H(+)-PPase, and the juice sac-predominant p-type proton pump gene (CsPH8) were significantly lower in 'HAL'. These results implied that 'HAL' has higher abilities for citrate biosynthesis and utilization, but lower ability for the citrate uptake into vacuole compared with 'AL'. Combined with the metabolites-analyzing results, a model was then established and suggested that the reduction in proton pump activity is the key factor for the low citrate accumulation and the comprehensive metabolite alterations as well in 'HAL'.
TL;DR: Flux-based modeling approaches are used to improve yields of fatty acids in Saccharomyces cerevisiae and combined 13C labeling data with comprehensive genome-scale models to shed light onto microbial metabolism and improve metabolic engineering efforts.
Abstract: Efficient redirection of microbial metabolism into the abundant production of desired bioproducts remains non-trivial. Here, we used flux-based modeling approaches to improve yields of fatty acids in Saccharomyces cerevisiae. We combined 13C labeling data with comprehensive genome-scale models to shed light onto microbial metabolism and improve metabolic engineering efforts. We concentrated on studying the balance of acetyl-CoA, a precursor metabolite for the biosynthesis of fatty acids. A genome-wide acetyl-CoA balance study showed ATP citrate lyase from Yarrowia lipolytica as a robust source of cytoplasmic acetyl-CoA and malate synthase as a desirable target for downregulation in terms of acetyl-CoA consumption. These genetic modifications were applied to S. cerevisiae WRY2, a strain that is capable of producing 460 mg/L of free fatty acids. With the addition of ATP citrate lyase and downregulation of malate synthase, the engineered strain produced 26% more free fatty acids. Further increases in free fatty acid production of 33% were obtained by knocking out the cytoplasmic glycerol-3-phosphate dehydrogenase, which flux analysis had shown was competing for carbon flux upstream with the carbon flux through the acetyl-CoA production pathway in the cytoplasm. In total, the genetic interventions applied in this work increased fatty acid production by ~70%.
TL;DR: It is concluded that adding OAA to SH‐SY5Y cells can support or enhance both glycolysis and respiration fluxes, and appears to depend, at least partly, on OAA causing a shift in the cell redox balance to a more oxidized state.
Abstract: We tested how the addition of oxaloacetate (OAA) to SH-SY5Y cells affected bioenergetic fluxes and infrastructure, and compared the effects of OAA to malate, pyruvate, and glucose deprivation. OAA displayed pro-glycolysis and pro-respiration effects. OAA pro-glycolysis effects were not a consequence of decarboxylation to pyruvate because unlike OAA, pyruvate lowered the glycolysis flux. Malate did not alter glycolysis flux and reduced mitochondrial respiration. Glucose deprivation essentially eliminated glycolysis and increased mitochondrial respiration. OAA increased, while malate decreased, the cell NAD+/NADH ratio. Cytosolic malate dehydrogenase 1 protein increased with OAA treatment, but not with malate or glucose deprivation. Glucose deprivation increased protein levels of ATP citrate lyase, an enzyme which produces cytosolic OAA, whereas OAA altered neither ATP citrate lyase mRNA nor protein levels. OAA, but not glucose deprivation, increased cytochrome oxidase subunit 2, PGC1α, PGC1β, and PGC1 related co-activator protein levels. OAA increased total and phosphorylated SIRT1 protein. We conclude that adding OAA to SH-SY5Y cells can support or enhance both glycolysis and respiration fluxes. These effects appear to depend, at least partly, on OAA causing a shift in the cell redox balance to a more oxidized state, that it is not a glycolysis pathway intermediate, and possibly its ability to act in an anaplerotic fashion. We examined how oxaloacetate (OAA) affects bioenergetic fluxes. To advance the understanding of how OAA mediates these changes, we compared the effects of OAA to malate, pyruvate, and glucose deprivation. We further examined how OAA affects levels of enzymes that facilitate its cytosolic metabolism, and found OAA increased the expression of malate dehydrogenase 1 (MDH1-cytosolic). We propose the following: OAA supports both glycolysis and respiration fluxes, shifts the cell redox balance toward a more oxidized state, and acts in an anaplerotic fashion. Abbreviations not defined in the text: MDH2, malate dehydrogenase 2 (mitochondrial).
TL;DR: It is revealed that hyperphosphorylation in ATP citrate lyase (ACL) occurs frequently in human breast tumors and correlates well with HER2+ and/or PIK3CA-mutant (HER2+/PIK3CAmut) status in breast tumor cell lines, revealing mTORC2 as a critical regulator of breast cancer metabolism.
Abstract: The mechanistic target of rapamycin (mTOR) is a major regulator of cell growth and is frequently dysregulated in cancer. While mTOR complex-1 (mTORC1) is a validated cancer target, the role of mTOR complex-2 (mTORC2) remains less defined. Here, we reveal mTORC2 as a critical regulator of breast cancer metabolism. We showed that hyperphosphorylation in ATP citrate lyase (ACL) occurs frequently in human breast tumors and correlates well with HER2+ and/or PIK3CA-mutant (HER2+/PIK3CAmut) status in breast tumor cell lines. In HER2+/PIK3CAmut cells, mTORC2 controls Ser-455 phosphorylation of ACL thereby promoting acetyl-CoA production, de novo lipogenesis and mitochondrial physiology, all of which were inhibited by an mTORC1/mTORC2 kinase inhibitor (mTOR-KI) or cellular depletion of mTORC2 or ACL. mTOR-KI but not rapamycin blocked the IGF-1-induced ACL phosphorylation and glucose to lipid conversion. Depletion of mTORC2 but not mTORC1 specifically inhibited the ACL-dependent acetyl-CoA production. In the HER2+/PIK3CAmut MDA361, MDA453, BT-474 and T47D cells, depletion of mTORC2 or ACL led to growth inhibition and mitochondrial hyperpolarization, which were partially rescued by an alternate source of acetyl-CoA. These same changes were not apparent in mTORC2- or ACL-depleted HER2-/PIK3CAwt MDA231 and HCC1806 cells, highlighting a differential dependence of mTORC2-ACL for survival in these two cell types. Moreover, ACL Ser-455 mutants S455E (phosphomimetic) and S455A (non-phosphorylatable) each increased or decreased, respectively, the acetyl-CoA production, mitochondrial homeostasis and survival in ACL-depleted MDA453 cells. These studies define a new and rapamycin-resistant mechanism of mTORC2-ACL in lipogenesis and acetyl-CoA biology and provide a rationale for targeting of mTORC1 and mTORC2 in HER2+/PIK3CAmut breast cancer.
TL;DR: The preliminary findings provide evidence for a citrate pathway dysregulation, which could be related to some phenotypic traits of people with Down syndrome, as well as in lipid peroxidation levels.
Abstract: Summary
Inflammatory conditions and oxidative stress have a crucial role in Down syndrome (DS). Emerging studies have also reported an altered lipid profile in the early stages of DS patient life. Our previous works demonstrate that the citrate pathway activation is required for oxygen radical production during inflammation. Here, we find an upregulation of the citrate pathway and a downregulation of carnitine/acylcarnitine carrier and carnitine palmitoyl-transferase 1 genes in cells from children with DS. Interestingly, when the citrate pathway is inhibited, we observe a reduction in oxygen radicals as well as in lipid peroxidation levels. Our preliminary findings provide evidence for a citrate pathway dysregulation, which could be related to some phenotypic traits of subjects with DS.
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TL;DR: Metabolic flux analysis of Y. lipolytica showed that flux through the pentose phosphate pathway was not significantly regulated by nitrogen concentration, suggesting that NADPH generation is not the limiting factor for lipid accumulation in this yeast.
Abstract: The oleaginous yeast Yarrowia lipolytica has considerable potential for producing single cell oil, which can be converted to biodiesel, a sustainable alternative to fossil fuels. However, extensive fundamental and engineering efforts must be carried out before commercialized production become cost-effective. Therefore, in this study, metabolic flux analysis of Y. lipolytica was performed using 13C-labeled glucose as a sole carbon source in nitrogen sufficient and insufficient media. The nitrogen limited medium inhibited cell growth while promoting lipid accumulation (from 8.7% of their biomass to 14.3%). Metabolic flux analysis showed that flux through the pentose phosphate pathway was not significantly regulated by nitrogen concentration, suggesting that NADPH generation is not the limiting factor for lipid accumulation in Y. lipolytica. Furthermore, metabolic flux through malic enzyme was undetectable, confirming its non-regulatory role in lipid accumulation in this yeast. Nitrogen limitation significantly increased flux through ATP:citrate lyase (ACL), implying that ACL plays a key role in providing acetyl-CoA for lipid accumulation in Y. lipolytica.
TL;DR: This work suggests that the malate transporter plays an important role in regulating lipid accumulation in oleaginous fungus M. circinelloides.
Abstract: Fatty acid biosynthesis in oleaginous fungi requires the supply of reducing power, NADPH, and the precursor of fatty acids, acetyl-CoA, which is generated in the cytosol being produced by ATP: citrate lyase which requires citrate to be, transported from the mitochondrion by the citrate/malate/pyruvate transporter. This transporter, which is within the mitochondrial membrane, transports cytosolic malate into the mitochondrion in exchange for mitochondrial citrate moving into the cytosol (Fig. 1). The role of malate transporter in lipid accumulation in oleaginous fungi is not fully understood, however. Therefore, the expression level of the mt gene, coding for a malate transporter, was manipulated in the oleaginous fungus Mucor circinelloides to analyze its effect on lipid accumulation. The results showed that mt overexpression increased the lipid content for about 70 % (from 13 to 22 % dry cell weight, CDW), whereas the lipid content in mt knockout mutant decreased about 27 % (from 13 to 9.5 % CDW) compared with the control strain. Furthermore, the extracellular malate concentration was decreased in the mt overexpressing strain and increased in the mt knockout strain compared with the wild-type strain. This work suggests that the malate transporter plays an important role in regulating lipid accumulation in oleaginous fungus M. circinelloides.
TL;DR: Differential behavior in citrate transport, metabolism and aroma generation of three strains are described and results that link citrate metabolism and genetic organizations in E. faecium are presented for the first time.
TL;DR: A broad view of storage lipid production in Scenedesmus species is provided with potential implications in designing suitable genetic interventions towards increase in lipid content vis-a-vis central carbon metabolism.
Abstract: Scenedesmus is considered as a potential oil-producing green microalgae having higher lipid content with suitable fatty acid profile (high oleic acid) for biodiesel production. Comparative transcriptome analysis of two Scenedesmus sp., viz. Scenedesmus dimorphus (26%) and Scenedesmus quadricauda (14%) having equivalent biomass and variable lipid content was performed to uncover molecular mechanisms controlling differential lipid production. 76,969 and 40,979 CDSs were predicted from the transcriptomes of S. dimorphus and S. quadricauda respectively, which were subsequently mapped to metabolic pathways. Overall up-regulation of metabolic pathways contributing precursors to storage lipid biosynthesis was observed in S. dimorphus. Glyceraldehyde 3-phosphate dehydrogenase, enolase, acetyl-CoA synthetase, pyruvate dehydrogenase, ATP citrate lyase, glycerol kinase, citrate synthase were identified as major regulators of high lipid content in S. dimorphus. Further, WRINKLED1 transcription factor significantly correlated with high lipid accumulation as revealed by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) in three growth stages of two species. This study provides a broad view of storage lipid production in Scenedesmus species with potential implications in designing suitable genetic interventions towards increase in lipid content vis-a-vis central carbon metabolism.
TL;DR: The fatty acid niacin conjugate 5 has been shown to be an inhibitor of the sterol regulatory element binding protein (SREBP), a key regulator of cholesterol metabolism proteins such as PCSK9, HMG-CoA reductase, ATP citrate lyase, and NPC1L1.
Abstract: This report describes the synthesis and preliminary biological characterization of novel fatty acid niacin conjugates and fatty acid salicylate conjugates. These molecular entities were created by covalently linking two bioactive molecules, either niacin or salicylic acid, to an omega-3 fatty acid. This methodology allows the simultaneous intracellular delivery of two bioactives in order to elicit a pharmacological response that could not be replicated by administering the bioactives individually or in combination. The fatty acid niacin conjugate 5 has been shown to be an inhibitor of the sterol regulatory element binding protein (SREBP), a key regulator of cholesterol metabolism proteins such as PCSK9, HMG-CoA reductase, ATP citrate lyase, and NPC1L1. On the other hand, the fatty acid salicylate conjugate 11 has been shown to have a unique anti-inflammatory profile based on its ability to modulate the NF-κB pathway through the intracellular release of the two bioactives.
TL;DR: The integrative analysis of transcriptomic, miRNA, degradome, metabolomics and proteomic data provided a strengthened understanding of radish response to Pb stress at multiple levels, and would be helpful for further dissecting molecular mechanism underlying plant response to HM stresses.
Abstract: Lead (Pb) is one of the most abundant heavy metal pollutants, which can penetrate the plant through the root and then enter the food chain causing in potential health risks for human beings. Radish is an important root vegetable crop worldwide. To investigate the mechanism underlying plant response to Pb stress in radish, the protein profile changes of radish roots were comprehensively analyzed using iTRAQ (Isobaric Tag for Relative and Absolute Quantification) respectively upon Pb(NO3)2 at 500 mg L-1(Pb500) and Pb(NO3)2 at 1000 mg L-1(Pb1000) exposure. A total of 3, 898 protein species were successfully detected and 2,141 were quantified. Among them, a subset of 721 protein species were differentially accumulated upon at least one Pb treatment, and 135 ones showed significantly abundance changes during both two Pb-stressed conditions. Many critical protein species related to protein translation, processing, and degradation, reactive oxygen species (ROS) scavenging, photosynthesis and respiration and carbon metabolism were successfully identified. Gene Ontology (GO) and pathway enrichment analysis of the 135 differential abundance protein species revealed that the overrepresented GO terms were include in ‘cell wall’, ‘apoplast’, ‘response to metal ion’, ‘vacuole’ and ‘peroxidase activity’, and the critical enriched pathways were involved in ‘citric acid (TCA) cycle and respiratory electron transport’, ‘pyruvate metabolism’, ‘phenylalanine metabolism’, ‘phenylpropanoid biosynthesis’ and ‘carbon metabolism’. Furthermore, the integrative analysis of transcriptomic, miRNA, degradome, metabolomic and proteomic data provided a strengthened understanding of radish response to Pb stress at multiple levels. Under Pb stress, many key enzymes (i.e. ATP citrate lyase, Isocitrate dehydrogenase, fumarate hydratase and malate dehydrogenase) involved in the glycolysis and TCA cycle were severely affected, which ultimately cause alteration of some metabolites including glucose, citrate, and malate. Meanwhile, a series of other defense responses including ascorbate (ASA)–glutathione (GSH) cycle for ROS scavenging and Pb-defense protein species (glutaredoxin, aldose 1-epimerase malate dehydrogenase and thioredoxin), were triggered to cope with Pb-induced injuries. The results would be helpful for further dissecting molecular mechanism underlying plant response to HM stresses, and facilitate effective management of HM contamination in vegetable crops by genetic manipulation.
TL;DR: An improvement of the SAT inflammatory and immune profile and an induction of genes involved in the regulation of lipid metabolism are shown when weight loss stabilizes 2 years after RYGB.
TL;DR: The results establish the involvement of the acetoacetate pathway in insulin secretion in pancreatic beta cells.
Abstract: Objective
Glucose-stimulated insulin secretion in pancreatic beta cells requires metabolic signals including the generation of glucose-derived short chain acyl-CoAs in the cytosol from mitochondrially-derived metabolites. One concept of insulin secretion is that ATP citrate lyase generates short chain acyl-CoAs in the cytosol from mitochondrially-derived citrate. Of these, malonyl-CoA, is believed to be an important signal in insulin secretion. Malonyl-CoA is also a precursor for lipids. Our recent evidence suggested that, in the mitochondria of beta cells, glucose-derived pyruvate can be metabolized to acetoacetate that is exported to the cytosol and metabolized to the same short chain acyl-CoAs and fatty acids that can be derived from citrate. We tested for redundancy of the citrate pathway.
TL;DR: Mild, but not severe, hypoxia stimulates lipolysis and promotes adipocyte differentiation, probably through excess of acetyl-CoA originating from tricarboxylic acid cycle independently of HIF activation.
TL;DR: It is concluded that, unlike rodents or humans, hepatic fatty acid biosynthetic gene expression in rainbow trout is more responsive to dietary protein intake/AAs than dietary carbohydrate intake/glucose during acute stimulations.
Abstract: The link between dietary carbohydrate/protein and de novo lipogenesis (DNL) remains debatable in carnivorous fish. We aimed to evaluate and compare the response of hepatic lipogenic gene expression to dietary carbohydrate intake/glucose and dietary protein intake/amino acids (AAs) during acute stimulations using both in vivo and in vitro approaches. For the in vivo trial, three different diets and a controlled-feeding method were employed to supply fixed amount of dietary protein or carbohydrate in a single meal; for the in vitro trial, primary hepatocytes were stimulated with a low or high level of glucose (3 mM or 20 mM) and a low or high level of AAs (one-fold or four-fold concentrated AAs). In vitro data showed that a high level of AAs upregulated the expression of enzymes involved in DNL [fatty acid synthase (FAS) and ATP citrate lyase (ACLY)], lipid bioconversion [elongation of very long chain fatty acids like-5 (Elovl5), Elovl2, Δ6 fatty acyl desaturase (D6D) and stearoyl-CoA desaturase-1 (SCD1)], NADPH production [glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme (ME)], and transcriptional factor sterol regulatory element binding protein 1-like, while a high level of glucose only elevated the expression of ME. Data in trout liver also showed that high dietary protein intake induced higher lipogenic gene expression (FAS, ACLY, and Elovl2) regardless of dietary carbohydrate intake, while high carbohydrate intake markedly suppressed the expression of acetyl-CoA carboxylase (ACC) and Elovl5. Overall, we conclude that, unlike rodents or humans, hepatic fatty acid biosynthetic gene expression in rainbow trout is more responsive to dietary protein intake/AAs than dietary carbohydrate intake/glucose during acute stimulations. This discrepancy probably represents one important physiological and metabolic difference between carnivores and omnivores.
TL;DR: The results are the first to show the crosstalk between polyamine and acetyl-CoA metabolism, and it is hypothesize that AZ may promote acetyl -CoA synthesis to downregulate spermidine and spermine through acetylation.
TL;DR: Investigation of the effect of HCA on lipid and lipoproteins content in the blood serum, as well as lipid content and activity of some lipid metabolism enzymes in the liver of hamsters with IR found the treatment by HCA reduces the manifestations of hyperlipidemia, but enhances the lipid accumulation in the Liver.
Abstract: The syndrome of insulin resistance (IR) is one of the leading reasons for the increased risk of cardiovascular diseases and their complications. Among the key components of IR are obesity and dyslipidemia. Hydroxycitric acid (HCA), an inhibitor of a key enzyme of lipogenesis ATP citrate lyase (ACLY) is a promising obesity treatment agent. The aim of this work was to investigate the effect of HCA on lipid and lipoproteins content in the blood serum, as well as lipid content and activity of some lipid metabolism enzymes in the liver of hamsters with IR. IR was modeled by keeping animals on high-fat diet with addition of fructose. Lipid content was determined by using standard reagent kits, the level of lipoproteins, the activity of glucose 6-phosphate dehydrogenase and ACLY – spectrophotometrically, lysosomal lipase activity – fluorimetrically. Development of hyperlipidemia and atherogenic dyslipidemia, lipid accumulation in the liver, activation of lysosomal lipase and ACLY and reduction of glucose 6-phosphate dehydrogenase activity were shown under IR. The treatment by HCA reduces the manifestations of hyperlipidemia, but enhances the lipid accumulation in the liver.
TL;DR: An overall suppression of lipogenesis due to AGP inhibition of lipogenic gene expression in vitro is demonstrated, which the metabolic data and SREBP, ChREBP and IRS1 gene expression analysis suggest is through an inhibition in insulin-mediated events.
Abstract: Serum α1-acid glycoprotein (AGP) is elevated during late gestation and at birth in the pig and rapidly declines postnatally. In contrast, the pig is born with minimal lipid stores in the adipose tissue, but rapidly accumulates lipid during the first week. The present study examined if AGP can affect adipose tissue metabolism in the neonatal pig. Isolated cell cultures or tissue explants were prepared from dorsal subcutaneous adipose tissue of preweaning piglets. Porcine AGP was used at concentrations of 0, 100, 1000 and 5000 ng/ml medium in 24 h incubations. AGP reduced the messenger RNA (mRNA) abundance of the lipogenic enzymes, malic enzyme (ME), fatty acid synthase and acetyl coA carboxylase by at least 40% (P<0.001). The activity of ME and citrate lyase were also reduced by AGP (P<0.05). Glucose oxidation was reduced by treatment with 5000 ng AGP/ml medium (P<0.05). The 14C-glucose incorporation into fatty acids was reduced by ~25% by AGP treatment for 24 h with 1000 ng AGP/ml medium (P<0.05). The decrease in glucose metabolism by AGP appears to function through an inhibition in insulin-mediated glucose oxidation and incorporation into fatty acids. This was supported by the analysis of the mRNA abundance for sterol regulatory element-binding protein (SREBP), carbohydrate regulatory element-binding protein (ChREBP) and insulin receptor substrate 1 (IRS1), which all demonstrated reductions of at least 23% in response to AGP treatment (P<0.05). These data demonstrate an overall suppression of lipogenesis due to AGP inhibition of lipogenic gene expression in vitro, which the metabolic data and SREBP, ChREBP and IRS1 gene expression analysis suggest is through an inhibition in insulin-mediated events. Second, these data suggest that AGP may contribute to limiting lipogenesis within adipose tissue during the perinatal period, as AGP levels are highest for any serum protein at birth.
TL;DR: In this article, cDNAs of the small and large subunits of ACL (DtACLA and DtACLB) and their genomic sequences were isolated from Dunaliella tertiolecta using RT-PCR, RACEs and genomic walking techniques.
Abstract: ATP-citrate lyase (ACL) catalyzes the formation of cytosolic acetyl-CoA, which is responsible for the biosynthesis of fatty acids, lipids, and flavonoid. Here, cDNAs of the small and large subunits of ACL (DtACLA and DtACLB) and their genomic sequences were isolated from Dunaliella tertiolecta using RT-PCR, RACEs and genomic walking techniques. It was found that there were 12 exons and 11 introns in DtACLA, and 20 exons and 19 introns in DtACLB. PlantPAN and PlantCARE revealed a number of putative transcription factor binding sites in the 5′-flanking regions of DtACLA and DtACLB. Conserved domain analysis and phylogenetic analysis showed that ACLA and SCSβ may share the common evolutionary origin, and ACLB may have a common origin from the fusion and divergence of SCSα and CS. The recombinant DtACLA and DtACLB in E. coli BL21 (DE3) seemed to be expressed mainly in the form of insoluble fraction. The transcription levels of DtACLA and DtACLB were fairly consistent with lipid accumulation in response to nitrogen deficiency, suggesting that both subunits of ACL from D. tertiolecta may be coordinate to function in the catalysis, and their activity was related to the lipid accumulation in D. tertiolecta.