scholarly journals Thioesterase superfamily member 2 (Them2)/acyl-CoA thioesterase 13 (Acot13): a homotetrameric hotdog fold thioesterase with selectivity for long-chain fatty acyl-CoAs

2009 ◽  
Vol 421 (2) ◽  
pp. 311-322 ◽  
Author(s):  
Jie Wei ◽  
Hye Won Kang ◽  
David E. Cohen
Keyword(s):  
Acyl Chain ◽  
Substrate Inhibition ◽  
Fatty Acyl ◽  
Mouse Heart ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Chain Acyl ◽  
Hotdog Fold ◽  
Long Chain ◽  
Myristoyl Coa

Them2 (thioesterase superfamily member 2) is a 140-amino-acid protein of unknown biological function that comprises a single hotdog fold thioesterase domain. On the basis of its putative association with mitochondria, accentuated expression in oxidative tissues and interaction with StarD2 (also known as phosphatidylcholine-transfer protein, PC-TP), a regulator of fatty acid metabolism, we explored whether Them2 functions as a physiologically relevant fatty acyl-CoA thioesterase. In solution, Them2 formed a stable homotetramer, which denatured in a single transition at 59.3 °C. Them2 exhibited thioesterase activity for medium- and long-chain acyl-CoAs, with Km values that decreased exponentially as a function of increasing acyl chain length. Steady-state kinetic parameters for Them2 were characteristic of long-chain mammalian acyl-CoA thioesterases, with minimal values of Km and maximal values of kcat/Km observed for myristoyl-CoA and palmitoyl-CoA. For these acyl-CoAs, substrate inhibition was observed when concentrations approached their critical micellar concentrations. The acyl-CoA thioesterase activity of Them2 was optimized at physiological temperature, ionic strength and pH. For both myristoyl-CoA and palmitoyl-CoA, the addition of StarD2 increased the kcat of Them2. Enzymatic activity was decreased by the addition of phosphatidic acid/phosphatidylcholine small unilamellar vesicles. Them2 expression, which was most pronounced in mouse heart, was associated with mitochondria and was induced by activation of PPARα (peroxisome-proliferator-activated receptor α). We conclude that, under biological conditions, Them2 probably functions as a homotetrameric long-chain acyl-CoA thioesterase. Accordingly, Them2 has been designated as the 13th member of the mammalian acyl-CoA thioesterase family, Acot13.

Distinct transcriptional regulation of long-chain acyl-CoA synthetase isoforms and cytosolic thioesterase 1 in the rodent heart by fatty acids and insulin

2006 ◽  
Vol 290 (6) ◽  
pp. H2480-H2497 ◽  
Author(s):  
David J. Durgan ◽  
Justin K. Smith ◽  
Margaret A. Hotze ◽  
Oluwaseun Egbejimi ◽  
Karalyn D. Cuthbert ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acyl ◽  
Null Mouse ◽  
Peroxisome Proliferator ◽  
Futile Cycle ◽  
Peroxisome Proliferator Activated Receptor ◽  
Rat Cardiomyocytes ◽  
Adult Rat ◽  
Chain Acyl ◽  
Long Chain

The molecular mechanism(s) responsible for channeling long-chain fatty acids (LCFAs) into oxidative versus nonoxidative pathways is (are) poorly understood in the heart. Intracellular LCFAs are converted to long-chain fatty acyl-CoAs (LCFA-CoAs) by a family of long-chain acyl-CoA synthetases (ACSLs). Cytosolic thioesterase 1 (CTE1) hydrolyzes cytosolic LCFA-CoAs to LCFAs, generating a potential futile cycle at the expense of ATP utilization. We hypothesized that ACSL isoforms and CTE1 are differentially regulated in the heart during physiological and pathophysiological conditions. Using quantitative RT-PCR, we report that the five known acsl isoforms ( acsl1, acsl3, acsl4, acsl5, and acsl6) and cte1 are expressed in whole rat and mouse hearts, as well as adult rat cardiomyocytes (ARCs). Streptozotocin-induced insulin-dependent diabetes (4 wk) and fasting (≤24 h) both dramatically induced cte1 and repressed acsl6 mRNA, with no significant effects on the other acsl isoforms. In contrast, high-fat feeding (4 wk) induced cte1 without affecting expression of the acsl isoforms in the heart. Investigation into the mechanism(s) responsible for these transcriptional changes uncovered roles for peroxisome proliferator-activated receptor-α (PPARα) and insulin as regulators of specific acsl isoforms and cte1 in the heart. Culturing ARCs with oleate (0.1–0.4 mM) or the PPARα agonists WY-14643 (1 μM) and fenofibrate (10 μM) consistently induced acsl1 and cte1. Conversely, PPARα null mouse hearts exhibited decreased acsl1 and cte1 expression. Culturing ARCs with insulin (10 nM) induced acsl6, whereas specific loss of insulin signaling within the heart (cardiac-specific insulin receptor knockout mice) caused decreased acsl6 expression. Our data expose differential regulation of acsl isoforms and cte1 in the heart, where acsl1 and cte1 are PPARα-regulated genes, whereas acsl6 is an insulin-regulated gene.

scholarly journals Involvement of the peroxisome proliferator-activated receptor α in regulating long-chain acyl-CoA thioesterases

2000 ◽  
Vol 41 (5) ◽  
pp. 814-823 ◽  
Author(s):  
Mary C. Hunt ◽  
Per J.G. Lindquist ◽  
Jeffrey M. Peters ◽  
Frank J. Gonzalez ◽  
Ulf Diczfalusy ◽  
...  
Keyword(s):  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Chain Acyl ◽  
Long Chain

scholarly journals Liver-specific knockdown of long-chain acyl-CoA synthetase 4 reveals its key role in VLDL-TG metabolism and phospholipid synthesis in mice fed a high-fat diet

2019 ◽  
Vol 316 (5) ◽  
pp. E880-E894 ◽  
Author(s):  
Amar B. Singh ◽  
Chin Fung K. Kan ◽  
Fredric B. Kraemer ◽  
Raymond A. Sobel ◽  
Jingwen Liu
Keyword(s):  
High Fat Diet ◽  
Plasma Cholesterol ◽  
Peroxisome Proliferator ◽  
Synthetase Activity ◽  
High Fat ◽  
Peroxisome Proliferator Activated Receptor ◽  
Insulin Resistant ◽  
Chain Acyl ◽  
Long Chain

Long-chain acyl-CoA synthetase 4 (ACSL4) has a unique substrate specificity for arachidonic acid. Hepatic ACSL4 is coregulated with the phospholipid (PL)-remodeling enzyme lysophosphatidylcholine (LPC) acyltransferase 3 by peroxisome proliferator-activated receptor δ to modulate the plasma triglyceride (TG) metabolism. In this study, we investigated the acute effects of hepatic ACSL4 deficiency on lipid metabolism in adult mice fed a high-fat diet (HFD). Adenovirus-mediated expression of a mouse ACSL4 shRNA (Ad-shAcsl4) in the liver of HFD-fed mice led to a 43% reduction of hepatic arachidonoyl-CoA synthetase activity and a 53% decrease in ACSL4 protein levels compared with mice receiving control adenovirus (Ad-shLacZ). Attenuated ACSL4 expression resulted in a substantial decrease in circulating VLDL-TG levels without affecting plasma cholesterol. Lipidomics profiling revealed that knocking down ACSL4 altered liver PL compositions, with the greatest impact on accumulation of abundant LPC species (LPC 16:0 and LPC 18:0) and lysophosphatidylethanolamine (LPE) species (LPE 16:0 and LPE 18:0). In addition, fasting glucose and insulin levels were higher in Ad-shAcsl4-transduced mice versus control (Ad-shLacZ). Glucose tolerance testing further indicated an insulin-resistant phenotype upon knockdown of ACSL4. These results provide the first in vivo evidence that ACSL4 plays a role in plasma TG and glucose metabolism and hepatic PL synthesis of hyperlipidemic mice.

scholarly journals Immunohistochemical staining reveals differential expression of ACSL3 and ACSL4 in hepatocellular carcinoma and hepatic gastrointestinal metastases

2020 ◽  
Vol 40 (4) ◽  
Author(s):  
Haarith Ndiaye ◽  
Jorlin Y. Liu ◽  
Andrew Hall ◽  
Shane Minogue ◽  
Marsha Y. Morgan ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Acyl Chain ◽  
Hepatic Metastases ◽  
Normal Liver ◽  
Subcellular Fractionation ◽  
Fatty Acyl ◽  
Liver Malignancies ◽  
Tissue Arrays ◽  
Chain Acyl ◽  
Long Chain

Abstract Long-chain fatty acyl CoA synthetases (ACSLs) activate fatty acids by CoA addition thus facilitating their intracellular metabolism. Dysregulated ACSL expression features in several cancers and can affect processes such as ferroptosis, fatty acid β-oxidation, prostaglandin biosynthesis, steroidogenesis and phospholipid acyl chain remodelling. Here we investigate long chain acyl-CoA synthetase 3 (ACSL3) and long chain acyl-CoA synthetase 4 (ACSL4) expression in liver malignancies. The expression and subcellular localisations of the ACSL3 and ACSL4 isoforms in hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA) and hepatic metastases were assessed by immunohistochemical analyses of multiple tumour tissue arrays and by subcellular fractionation of cultured HepG2 cells. The expression of both enzymes was increased in HCC compared with normal liver. Expression of ACSL3 was similar in HCC and hepatic metastases but lower in healthy tissue. Increased ACSL3 expression distinguished HCC from CCA with a sensitivity of 87.2% and a specificity of 75%. ACSL4 expression was significantly greater in HCC than in all other tumours and distinguished HCC from normal liver tissue with a sensitivity of 93.8% and specificity of 93.6%. Combined ACSL3 and ACSL4 staining scores distinguished HCC from hepatic metastases with 80.1% sensitivity and 77.1% specificity. These enzymes had partially overlapping intracellular distributions, ACSL4 localised to the plasma membrane and both isoforms associated with lipid droplets and the endoplasmic reticulum (ER). In conclusion, analysis of ACSL3 and ACSL4 expression can distinguish different classes of hepatic tumours.

scholarly journals Peroxisomal β-oxidation of long-chain fatty acids possessing different extents of unsaturation

1987 ◽  
Vol 247 (3) ◽  
pp. 531-535 ◽  
Author(s):  
R Hovik ◽  
H Osmundsen
Keyword(s):  
Fatty Acids ◽  
Substrate Inhibition ◽  
Fatty Acyl ◽  
Long Chain Fatty Acids ◽  
Beta Oxidation ◽  
Long Chain ◽  
Myristoyl Coa ◽  
Chain Fatty Acids

Rates of peroxisomal beta-oxidation were measured as fatty acyl-CoA-dependent NAD+ reduction, by using solubilized peroxisomal fractions isolated from livers of rats treated with clofibrate. Medium- to long-chain saturated fatty acyl-CoA esters as well as long-chain polyunsaturated fatty acyl-CoA esters were used. Peroxisomal beta-oxidation shows optimal specificity towards long-chain polyunsaturated acyl-CoA esters. Eicosa-8,11,14-trienoyl-CoA, eicosa-11,14,17-trienoyl-CoA and docosa-7,10,13,16-tetraenoyl-CoA all gave Vmax. values of about 150% of that obtained with palmitoyl-CoA. The Km values obtained with these fatty acyl-CoA esters were 17 +/- 6, 13 +/- 4 and 22 +/- 3 microM respectively, which are in the same range as the value for palmitoyl-CoA (13.8 +/- 1 microM). Myristoyl-CoA gave the higher Vmax. (110% of the palmitoyl-CoA value) of the saturated fatty acyl-CoAs tested. Substrate inhibition was mostly observed with acyl-CoA esters giving Vmax. values higher than 50% of that given by palmitoyl-CoA.

scholarly journals Effect of long-chain fatty acyl-CoA on mitochondrial and cytosolic ATP/ADP ratios in the intact liver cell

1984 ◽  
Vol 220 (2) ◽  
pp. 371-376 ◽  
Author(s):  
S Soboll ◽  
H J Seitz ◽  
H Sies ◽  
B Ziegler ◽  
R Scholz
Keyword(s):  
Liver Cell ◽  
Adenine Nucleotide ◽  
Intact Cell ◽  
Inhibitory Effect ◽  
Fatty Acyl ◽  
Fed State ◽  
Physiological Relevance ◽  
Chain Acyl ◽  
Long Chain

The effect of long-chain acyl-CoA on subcellular adenine nucleotide systems was studied in the intact liver cell. Long-chain acyl-CoA content was varied by varying the nutritional state (fed and starved states) or by addition of oleate. Starvation led to an increase in the mitochondrial and a decrease in the cytosolic ATP/ADP ratio in liver both in vivo and in the isolated perfused organ as compared with the fed state. The changes were reversed on re-feeding glucose in liver in vivo or on infusion of substrates (glucose, glycerol) in the perfused liver, respectively. Similar changes in mitochondrial and cytosolic ATP/ADP ratios occurred on addition of oleate, but, importantly, not with a short-chain fatty acid such as octanoate. It is concluded that long-chain acyl-CoA exerts an inhibitory effect on mitochondrial adenine nucleotide translocation in the intact cell, as was previously postulated in the literature from data obtained with isolated mitochondria. The physiological relevance with respect to pyruvate metabolism, i.e. regulation of pyruvate carboxylase and pyruvate dehydrogenase by the mitochondrial ATP/ADP ratio, is discussed.

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