Triacylglycerol synthesis and diacylglycerol acyltransferase activity during skeletal myogenesis

1990 ◽  
Vol 68 (12) ◽  
pp. 1393-1401 ◽  
Author(s):  
Victor S. Sauro ◽  
Kenneth P. Strickland
Keyword(s):  
Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
Diacylglycerol Acyltransferase ◽  
Skeletal Myogenesis ◽  
Acyltransferase Activity ◽  
Triacylglycerol Synthesis ◽  
Tag Accumulation ◽  
Long Chain

The role that diacylglycerol acyltransferase (DAGAT) may play in the switch in lipid metabolism from predominantly triacylglycerol- and phospholipid-synthesizing myoblasts to predominantly phospholipid-synthesizing myotubes has been studied during L6 skeletal myogenesis. Fatty acid induced triacylglycerol (TAG) accumulation in vivo was found to be optimal with long-chain, unsaturated fatty acids. The fatty acid induced TAG accumulation was significantly greater in myoblasts than that in myotubes. DAGAT activity in vitro was found to be associated with the particulate (membrane) fraction only. The inhibition by many thiol-specific reagents (N-ethylmaleimide, p-chloromercuribenzoate, iodoacetate, 5,5′-dithiobis(2-nitrobenzoic acid)) suggest that a thiol group is at or near the active site. In general, optimal DAGAT activity in vitro was observed when long-chain unsaturated acyl-CoAs and diacylglycerols (DAGs) containing long acyl chains were used as substrates for in vitro TAG synthesis (although 1,2-didecanoin was also very effective). DAGAT activity (expressed relative to DNA) was shown to decline over twofold during skeletal myogenesis when measured in the absence of exogenous DAG. However, in the presence of exogenous (1 mM) DAG, there was no significant change in DAGAT activity, suggesting that the levels of this enzyme are not altered during skeletal myogenesis. These results indicate that endogenous DAG levels are limiting TAG synthesis in L6 myotubes. However, DAG content of myotubes was significantly greater than that of myoblasts, suggesting that there may be an increased competition for DAG (perhaps owing to enhanced phospholipid synthesis) during skeletal myogenesis. The combined effects of decreased synthesis and increased degradation (reported earlier) of TAG may account for the decrease in endogenous TAG contents observed during skeletal myogenesis.Key words: diacylglycerol acyltransferase, TAG synthesis, skeletal myogenesis.

Substrate preferences of long-chain acyl-CoA synthetase and diacylglycerol acyltransferase contribute to enrichment of flax seed oil with α-linolenic acid

2018 ◽  
Vol 475 (8) ◽  
pp. 1473-1489 ◽  
Author(s):  
Yang Xu ◽  
Roman Holic ◽  
Darren Li ◽  
Xue Pan ◽  
Elzbieta Mietkiewska ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Linolenic Acid ◽  
Seed Oil ◽  
Diacylglycerol Acyltransferase ◽  
Acyl Donor ◽  
Flax Seed ◽  
Chain Acyl ◽  
Long Chain

Seed oil from flax (Linum usitatissimum) is enriched in α-linolenic acid (ALA; 18:3Δ9cis,12cis,15cis), but the biochemical processes underlying the enrichment of flax seed oil with this polyunsaturated fatty acid are not fully elucidated. Here, a potential process involving the catalytic actions of long-chain acyl-CoA synthetase (LACS) and diacylglycerol acyltransferase (DGAT) is proposed for ALA enrichment in triacylglycerol (TAG). LACS catalyzes the ATP-dependent activation of free fatty acid to form acyl-CoA, which in turn may serve as an acyl-donor in the DGAT-catalyzed reaction leading to TAG. To test this hypothesis, flax LACS and DGAT cDNAs were functionally expressed in Saccharomyces cerevisiae strains to probe their possible involvement in the enrichment of TAG with ALA. Among the identified flax LACSs, LuLACS8A exhibited significantly enhanced specificity for ALA over oleic acid (18:1Δ9cis) or linoleic acid (18:2Δ9cis,12cis). Enhanced α-linolenoyl-CoA specificity was also observed in the enzymatic assay of flax DGAT2 (LuDGAT2-3), which displayed ∼20 times increased preference toward α-linolenoyl-CoA over oleoyl-CoA. Moreover, when LuLACS8A and LuDGAT2-3 were co-expressed in yeast, both in vitro and in vivo experiments indicated that the ALA-containing TAG enrichment process was operative between LuLACS8A- and LuDGAT2-3-catalyzed reactions. Overall, the results support the hypothesis that the cooperation between the reactions catalyzed by LACS8 and DGAT2 may represent a route to enrich ALA production in the flax seed oil.

scholarly journals Effects of streptozotocin-diabetes and insulin administration in vivo or in vitro on the activities of five enzymes in the adipose-tissue triacylglycerol-synthesis pathway

1987 ◽  
Vol 243 (1) ◽  
pp. 289-292 ◽  
Author(s):  
E D Saggerson ◽  
C A Carpenter
Keyword(s):  
Insulin Treatment ◽  
Streptozotocin Diabetes ◽  
Diacylglycerol Acyltransferase ◽  
Fatty Acyl ◽  
Diabetic Rats ◽  
Insulin Administration ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase

At 2 days after administration of streptozotocin (100 mg/kg), activities in rat epididymal fat-pads of the following enzymes were significantly decreased: fatty acyl-CoA synthetase (FAS), mitochondrial and microsomal forms of glycerolphosphate acyltransferase (GPAT), monoacylglycerolphosphate acyltransferase (MGPAT) and Mg2+-dependent phosphatidate phosphohydrolase (PPH). There were no significant changes in diacylglycerol acyltransferase or Mg2+-independent PPH. Insulin administration to diabetic rats over 2 days restored activities of FAS, both forms of GPAT, MGPAT and Mg2+-dependent PPH. Significant restoration of all five activities was also seen 2 h after a single administration of insulin, but was not observed 45 min after insulin treatment. Insulin significantly increased all five enzyme activities when adipocytes from diabetic rats were incubated for 2 h with a mixture of glucose, lactate, pyruvate and amino acids.

Myocardial carnitine palmitoyltransferase I expression and long-chain fatty acid oxidation in fetal and newborn lambs

2004 ◽  
Vol 286 (6) ◽  
pp. H2243-H2248 ◽  
Author(s):  
Beatrijs Bartelds ◽  
Janny Takens ◽  
Gioia B. Smid ◽  
Victor A. Zammit ◽  
Carina Prip-Buus ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Left Ventricular ◽  
Chain Fatty Acid ◽  
Carnitine Palmitoyltransferase ◽  
Long Chain Fatty Acid ◽  
Carnitine Palmitoyltransferase I ◽  
Cpt I ◽  
Long Chain

Carnitine palmitoyltransferase I (CPT I) catalyzes the conversion of acyl-CoA to acylcarnitine at the outer mitochondrial membrane and is a key enzyme in the control of long-chain fatty acid (LC-FA) oxidation. Because myocardial LC-FA oxidation increases dramatically after birth, we determined the extent to which CPT I expression contributes to these changes in the perinatal lamb. We measured the steady-state level of transcripts of the CPT1A and CPT1B genes, which encode the liver (L-CPT I) and muscle CPT I (M-CPT I) isoforms, respectively, as well as the amount of these proteins, their total activity, and the amount of carnitine in left ventricular tissue from fetal and newborn lambs. We compared these data with previously obtained myocardial FA oxidation rates in vivo in the same model. The results showed that CPT1B was already expressed before birth and that total CPT I expression transiently increased after birth. The protein level of M-CPT I was high throughout development, whereas that of L-CPT I was only transiently upregulated in the first week after birth. The total CPT I activity in vitro also increased after birth. However, the increase in myocardial FA oxidation measured in vivo (112-fold) by far exceeded the increase in gene expression (2.2-fold), protein amount (1.1-fold), and enzyme activity (1.2-fold) in vitro. In conclusion, these results stress the importance of substrate supply per se in the postnatal increase in myocardial FA oxidation. M-CPT I is expressed throughout perinatal development, making it a primary target for metabolic modulation of myocardial FA oxidation.

scholarly journals In Vivo Optical Metabolic Imaging of Long-Chain Fatty Acid Uptake in Orthotopic Models of Triple-Negative Breast Cancer

Cancers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 148
Author(s):  
Megan C. Madonna ◽  
Joy E. Duer ◽  
Joyce V. Lee ◽  
Jeremy Williams ◽  
Baris Avsaroglu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Fatty Acid ◽  
Triple Negative ◽  
Fatty Acid Uptake ◽  
Chain Fatty Acid ◽  
Acid Uptake ◽  
Long Chain Fatty Acid ◽  
Long Chain

Targeting a tumor’s metabolic dependencies is a clinically actionable therapeutic approach; however, identifying subtypes of tumors likely to respond remains difficult. The use of lipids as a nutrient source is of particular importance, especially in breast cancer. Imaging techniques offer the opportunity to quantify nutrient use in preclinical tumor models to guide development of new drugs that restrict uptake or utilization of these nutrients. We describe a fast and dynamic approach to image fatty acid uptake in vivo and demonstrate its relevance to study both tumor metabolic reprogramming directly, as well as the effectiveness of drugs targeting lipid metabolism. Specifically, we developed a quantitative optical approach to spatially and longitudinally map the kinetics of long-chain fatty acid uptake in in vivo murine models of breast cancer using a fluorescently labeled palmitate molecule, Bodipy FL c16. We chose intra-vital microscopy of mammary tumor windows to validate our approach in two orthotopic breast cancer models: a MYC-overexpressing, transgenic, triple-negative breast cancer (TNBC) model and a murine model of the 4T1 family. Following injection, Bodipy FL c16 fluorescence increased and reached its maximum after approximately 30 min, with the signal remaining stable during the 30–80 min post-injection period. We used the fluorescence at 60 min (Bodipy60), the mid-point in the plateau region, as a summary parameter to quantify Bodipy FL c16 fluorescence in subsequent experiments. Using our imaging platform, we observed a two- to four-fold decrease in fatty acid uptake in response to the downregulation of the MYC oncogene, consistent with findings from in vitro metabolic assays. In contrast, our imaging studies report an increase in fatty acid uptake with tumor aggressiveness (6NR, 4T07, and 4T1), and uptake was significantly decreased after treatment with a fatty acid transport inhibitor, perphenazine, in both normal mammary pads and in the most aggressive 4T1 tumor model. Our approach fills an important gap between in vitro assays providing rich metabolic information at static time points and imaging approaches visualizing metabolism in whole organs at a reduced resolution.

scholarly journals Dietary Coleus Amboinicus Herb Decreases Ruminal Methanogenesis and Biohydrogenation, and Improves Meat Quality and Fatty Acid Composition in Longissimus Thoracis of Lambs

2021 ◽  
Author(s):  
Yulianri Rizki Yanza ◽  
Malgorzata Szumacher-Strabel ◽  
Dorota Lechniak ◽  
Sylwester Ślusarczyk ◽  
Pawel Kolodziejski ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Meat Quality ◽  
Methane Production ◽  
Fatty Acid Synthase ◽  
Unsaturated Fatty Acids ◽  
Biologically Active ◽  
Coleus Amboinicus

Abstract Background: This study aimed to investigate the effect of biologically active compounds (BAC) of Coleus amboinicus Lour. (CAL) herb fed to growing lambs on ruminal methane production, ruminal biohydrogenation of unsaturated fatty acids and meat characteristics. An in vitro trial (Experiment 1) comprising of control and three experimental diets (CAL constituting 10%, 15%, and 20% of the total diet) was conducted to determine an effective dose for in vivo experiments. After the in vitro trial, two in vivo experiments were conducted on six growing, rumen-cannulated lambs (Experiment 2) and 16 growing lambs (Experiment 3), which were assigned into the control (CON) and one experimental diet (20% of CAL). Several parameters were examined in vitro (pH, ammonia and VFA concentrations, protozoa, methanogens and select bacteria populations) and in vivo (methane production, digestibility, ruminal microorganism populations, meat quality, fatty acids profiles in rumen fluid and meat, transcript expression of 5 genes in meat). Results: The CAL lowered in vitro methane production by 51%. In the in vivo experiments, lambs fed CAL decreased methane production by 20% compared with the CON animals (Experiment 3), which corresponded to the reduced total methanogens counts in all experiments up to 28%, notably Methanobacteriales. In Experiment 3, CAL increased or tended to increase the numbers of Ruminococcus albus, Megasphaeraelsdenii, Butyrivibrioproteoclasticus, and Butyrivibriofibrisolvens. Dietary CAL suppressed the Holotricha population, but increased or tended to increase Entodiniomorpha population in Experiments 2 and 3. An increase in the polyunsaturated fatty acid (PUFA) proportion in the rumen of lambs was noted in response to the CAL diet, which was mainly attributable to the increase in C18:3 cis-9 cis-12 cis-15 (LNA) proportion. The CAL reduced the mRNA expressions of four investigated genes in meat (fatty acid synthase, stearoyl-CoA desaturase, lipoprotein lipase, and fatty acid desaturase 1). Conclusions:Summarizing, polyphenols of CAL (20% in diet) origin can mitigate ruminal methane production by inhibiting the methanogens communities. Supplementation of CAL also provides favorable conditions in the rumen by modulating ruminal bacteria involved in fermentation and biohydrogenation of fatty acids. CAL elevated the LNA concentration, which led to improved meat quality through increased deposition of n-3 PUFA.

scholarly journals Type II Diacylglycerol Acyltransferase from Claviceps purpurea with Ricinoleic Acid, a Hydroxyl Fatty Acid of Industrial Importance, as Preferred Substrate

2009 ◽  
Vol 76 (4) ◽  
pp. 1135-1142 ◽  
Author(s):  
Ioannis Mavraganis ◽  
Dauenpen Meesapyodsuk ◽  
Patricia Vrinten ◽  
Mark Smith ◽  
Xiao Qiu
Keyword(s):  
Fatty Acid ◽  
Ricinoleic Acid ◽  
Biochemical Characterization ◽  
Diacylglycerol Acyltransferase ◽  
Acyl Donor ◽  
Claviceps Purpurea ◽  
Type Ii ◽  
Acyl Acceptor

ABSTRACT Claviceps purpurea, the fungal pathogen that causes the cereal disease ergot, produces glycerides that contain high levels of ricinoleic acid [(R)-12-hydroxyoctadec-cis-9-enoic acid] in its sclerotia. Recently, a fatty acid hydroxylase (C. purpurea FAH [CpFAH]) involved in the biosynthesis of ricinoleic acid was identified from this fungus (D. Meesapyodsuk and X. Qiu, Plant Physiol. 147:1325-1333, 2008). Here, we describe the cloning and biochemical characterization of a C. purpurea type II diacylglycerol acyltransferase (CpDGAT2) involved in the assembly of ricinoleic acid into triglycerides. The CpDGAT2 gene was cloned by degenerate RT-PCR (reverse transcription-PCR). The expression of this gene restored the in vivo synthesis of triacylglycerol (TAG) in the quadruple mutant strain Saccharomyces cerevisiae H1246, in which all four TAG biosynthesis genes (DGA1, LRO1, ARE1, and ARE2) are disrupted. In vitro enzymatic assays using microsomal preparations from the transformed yeast strain indicated that CpDGAT2 prefers ricinoleic acid as an acyl donor over linoleic acid, oleic acid, or linolenic acid, and it prefers 1,2-dioleoyl-sn-glycerol over 1,2-dipalmitoyl-sn-glycerol as an acyl acceptor. The coexpression of CpFAH with CpDGAT2 in yeast resulted in an increased accumulation of ricinoleic acid compared to the coexpression of CpFAH with the native yeast DGAT2 (S. cerevisiae DGA1 [ScDGA1]) or the expression of CpFAH alone. Northern blot analysis indicated that CpFAH is expressed solely in sclerotium cells, with no transcripts of this gene being detected in mycelium or conidial cells. CpDGAT2 was more widely expressed among the cell types examined, although expression was low in conidiospores. The high expression of CpDGAT2 and CpFAH in sclerotium cells, where high levels of ricinoleate glycerides accumulate, provided further evidence supporting the roles of CpDGAT2 and CpFAH as key enzymes for the synthesis and assembly of ricinoleic acid in C. purpurea.

scholarly journals Factors influencing triacylglycerol synthesis in permeabilized rat hepatocytes

1992 ◽  
Vol 283 (3) ◽  
pp. 719-725 ◽  
Author(s):  
H K Stals ◽  
G P Mannaerts ◽  
P E Declercq
Keyword(s):  
Fatty Acid ◽  
Acid Concentration ◽  
Rat Hepatocytes ◽  
Diacylglycerol Acyltransferase ◽  
Relative Activity ◽  
Fatty Acid Concentration ◽  
Permeabilized Cells ◽  
Triacylglycerol Synthesis ◽  
Esterification Rate

Rat hepatocytes were treated with Staphylococcus aureus alpha-toxin to permeabilize their plasma membrane for low-molecular-mass compounds. During incubation with 1 mM labelled fatty acid, phosphatidate and, less clearly, lysophosphatidate rapidly reached a steady state, whereas labelled diacylglycerol accumulated to some extent, at least in the absence of exogenous CDP-choline. Esterification and oxidation were linearly related to the fatty acid concentration, and there was no indication for saturation with acyl-CoA. However, when permeabilized cells were incubated with labelled sn-glycerol 3-phosphate and 1 mM unlabelled fatty acid, glycerolipid synthesis and the level of esterification intermediates reached a plateau between 0.25 and 0.50 mumol of the triose phosphate/ml. The synthesis of phosphatidylcholine was dependent on addition of CDP-choline. In presence of the latter, diacylglycerol no longer accumulated and triacylglycerol synthesis was suppressed, although the sum of synthesized diacylglycerol, triacylglycerol and phosphatidylcholine remained constant. This indicates that the same pool of diacylglycerol is shared by choline-phosphotransferase and diacylglycerol acyltransferase and that the relative activity of these enzymes depends on the CDP-choline supply. Comparison of the levels of the esterification intermediates with the activity of the respective steps of the pathway reveals that, at a fixed fatty acid concentration, glycerophosphate acyltransferase determines the esterification rate, whereas lysophosphatidate acyltransferase and, at low CDP-choline levels, diacylglycerol acyltransferase approach saturation at elevated sn-glycerol 3-phosphate concentration. There is, however, no indication for a regulatory role of phosphatidate phosphohydrolase in this system. The significance of these findings for the regulation of triacylglycerol synthesis under conditions in vivo is discussed.

scholarly journals A Bi-Enzymatic Cascade Pathway Towards FAHFAs

2021 ◽  
Author(s):  
Yan Zhang ◽  
Bekir Engin Eser ◽  
Zheng Guo
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
Operation Mode ◽  
Hydroxy Fatty Acids ◽  
Fatty Acid Esters ◽  
One Pot ◽  
Preparative Scale

Recently discovered endogenous mammalian lipids fatty acid esters of hydroxy fatty acids (FAHFAs), proved to <a></a><a>have anti-inflammatory and anti-diabetic effects</a>. Due to their extremely low abundancies <i>in vivo</i>, forging a feasible scenario for FAHFA synthesis is critical for their use in uncovering biological mechanism or clinical trials. Here, we showcase a fully enzymatic approach, a novel <i>in vitro</i> bi-enzymatic cascade system, enabling an effective conversion of nature-abundant fatty acid into FAHFAs. Two hydratases <a></a><a>from <i>L. acidophilus</i> </a>were used for converting unsaturated fatty acids to various stereospecific hydroxy fatty acids, followed by esterification with another fatty acid catalyzed by <i>C. antarctica</i> lipase A (CALA). Various FAHFAs were synthesized in a preparative scale using this bi-enzymatic approach in a one-pot two-step operation mode. In all, we demonstrated that hydratase-CALA system promises a sustainable solution to the synthesis of structure-diverse stereospecific FAHFAs.

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