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Prasad A, Sreedharan S, Bakthavachalu B, Laxman S. Eggs of the mosquito Aedes aegypti survive desiccation by rewiring their polyamine and lipid metabolism. PLoS Biol 2023; 21:e3002342. [PMID: 37874799 PMCID: PMC10597479 DOI: 10.1371/journal.pbio.3002342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 09/20/2023] [Indexed: 10/26/2023] Open
Abstract
Upon water loss, some organisms pause their life cycles and escape death. While widespread in microbes, this is less common in animals. Aedes mosquitoes are vectors for viral diseases. Aedes eggs can survive dry environments, but molecular and cellular principles enabling egg survival through desiccation remain unknown. In this report, we find that Aedes aegypti eggs, in contrast to Anopheles stephensi, survive desiccation by acquiring desiccation tolerance at a late developmental stage. We uncover unique proteome and metabolic state changes in Aedes embryos during desiccation that reflect reduced central carbon metabolism, rewiring towards polyamine production, and enhanced lipid utilisation for energy and polyamine synthesis. Using inhibitors targeting these processes in blood-fed mosquitoes that lay eggs, we infer a two-step process of desiccation tolerance in Aedes eggs. The metabolic rewiring towards lipid breakdown and dependent polyamine accumulation confers resistance to desiccation. Furthermore, rapid lipid breakdown is required to fuel energetic requirements upon water reentry to enable larval hatching and survival upon rehydration. This study is fundamental to understanding Aedes embryo survival and in controlling the spread of these mosquitoes.
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Affiliation(s)
- Anjana Prasad
- Tata Institute for Genetics and Society (TIGS) Centre at inStem, Bangalore, India
- Institute for Stem Cell Science and Regenerative Medicine (DBT-inStem), Bangalore, India
| | - Sreesa Sreedharan
- Institute for Stem Cell Science and Regenerative Medicine (DBT-inStem), Bangalore, India
- SASTRA University, Thirumalaisamudram, Thanjavur, India
| | - Baskar Bakthavachalu
- Tata Institute for Genetics and Society (TIGS) Centre at inStem, Bangalore, India
- School of Biosciences and Bioengineering, Indian Institute of Technology Mandi, Mandi, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (DBT-inStem), Bangalore, India
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Franke J, Hertweck C. Biomimetic Thioesters as Probes for Enzymatic Assembly Lines: Synthesis, Applications, and Challenges. Cell Chem Biol 2016; 23:1179-1192. [PMID: 27693058 DOI: 10.1016/j.chembiol.2016.08.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/09/2016] [Accepted: 08/31/2016] [Indexed: 10/20/2022]
Abstract
Thioesters play essential roles in many biosynthetic pathways to fatty acids, esters, polyketides, and non-ribosomal peptides. Coenzyme A (CoA) and related phosphopantetheine thioesters are typically employed as activated acyl units for diverse C-C, C-O, and C-N coupling reactions. To study and control these enzymatic assembly lines in vitro and in vivo structurally simplified analogs such as N-acetylcysteamine (NAC) thioesters have been developed. This review gives an overview on experimental strategies enabled by synthetic NAC thioesters, such as the elucidation of complex biosynthetic pathways and enzyme mechanisms as well as precursor-directed biosynthesis and mutasynthesis. The review also summarizes synthetic protocols and protection group strategies to access these versatile synthetic tools, which are reactive and often unstable compounds. In addition, alternative phosphopantetheine thioester mimics are presented that can be used as protein tags or suicide inhibitors for protein crosslinking and off-loading probes to elucidate polyketide intermediates.
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Affiliation(s)
- Jakob Franke
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstraße 11a, 07745 Jena, Germany
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstraße 11a, 07745 Jena, Germany; Friedrich Schiller University, 07743 Jena, Germany.
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Gan J, Ma S, Zhang D. Non-cytochrome P450-mediated bioactivation and its toxicological relevance. Drug Metab Rev 2016; 48:473-501. [DOI: 10.1080/03602532.2016.1225756] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Brown LA, Larson TR, Graham IA, Hawes C, Paudyal R, Warriner SL, Baker A. An inhibitor of oil body mobilization in Arabidopsis. THE NEW PHYTOLOGIST 2013; 200:641-649. [PMID: 24033128 DOI: 10.1111/nph.12467] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/25/2013] [Indexed: 05/12/2023]
Abstract
Fatty acid β-oxidation is an essential process in many aspects of plant development, and storage oil in the form of triacylglycerol (TAG) is an important food source for humans and animals, for biofuel and for industrial feedstocks. In this study we characterize the effects of a small molecule, diphenyl methylphosphonate, on oil mobilization in Arabidopsis thaliana. Confocal laser scanning microscopy, transmission electron microscopy and quantitative lipid profiling were used to examine the effects of diphenyl methylphosphonate treatment on seedlings. Diphenyl methylphosphonate causes peroxisome clustering around oil bodies but does not affect morphology of other cellular organelles. We show that this molecule blocks the breakdown of pre-existing oil bodies resulting in retention of TAG and accumulation of acyl CoAs. The biochemical and phenotypic effects are consistent with a block in the early part of the β-oxidation pathway. Diphenyl methylphosphonate appears to be a fairly specific inhibitor of TAG mobilization in plants and whilst further work is required to identify the molecular target of the compound it should prove a useful tool to interrogate and manipulate these pathways in a controlled and reproducible manner.
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Affiliation(s)
- Laura-Anne Brown
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Tony R Larson
- Centre for Novel Agricultural Products, Department of Biology, University of York, Wentworth Way, Heslington, York, YO10 5DD, UK
| | - Ian A Graham
- Centre for Novel Agricultural Products, Department of Biology, University of York, Wentworth Way, Heslington, York, YO10 5DD, UK
| | - Chris Hawes
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Rupesh Paudyal
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Stuart L Warriner
- School of Chemistry, Faculty of Mathematics and Physical Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Alison Baker
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
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Marina Prendes MG, García JV, Testoni G, Fernández MA, Perazzo JC, Savino EA, Varela A. Influence of fasting on the effects of dimethylamiloride and oxfenicine on ischaemic-reperfused rat hearts. Arch Physiol Biochem 2006; 112:31-6. [PMID: 16754201 DOI: 10.1080/13813450500500357] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
To assess whether glycolysis, Na+-H+ exchange and oxidation of fatty acid derived from endogenous lipolysis are involved in the beneficial effects of 24-h fasting on the ischaemic - reperfused heart, it was studied the effects of inhibiting Na+ - H+ exchange using 10 muM dimethylamiloride and fatty acid oxidation using 2 mM oxfenicine, on the functional activity, lactate production and cell viability measured with tetrazolium stain. Since fasting accelerates heart fatty acid oxidation, data were compared to those from fed rats; using Langendorff perfused (glucose 10 mM) hearts of 250-350 g Wistar rats exposed to 25 min ischaemia - 30 min reperfusion. Fasting reduced the ischaemic rise of end diastolic pressure (contracture), improved recovery of contraction and lowered lactate production in comparison with the fed whereas cellular viability was similar in both groups. Dimethylamiloride improved the recovery of contraction (fed control 24 +/- 9%, fed treated 68 +/- 11%, P < 0.05 at the end of reperfusion), attenuated the contracture (fed control 40 +/- 9%, fed treated 24 +/- 11%, P < 0.05 at the beginning of reperfusion) and reduced lactate production in the fed group and increased cellular viability in both groups (fed control 21 +/- 6%, fed treated 69 +/- 7%, P < 0.05, and fasted control 18 +/- 7%, fasted treated 53 +/- 8%, P < 0.05). Oxfenicine reduced the recovery of contraction (fasted control 88 +/- 6%, fasted treated 60 +/- 11%, P < 0.05) and increased lactate production of fasted group and attenuated the contracture in the fed. These data suggest that beneficial effects of fasting owe, at least in part, to a lowered glycolysis probably secondary to the increased fatty acid oxidation and to the accumulation of energy supplying acyl esters. Dimethylamiloride slowing of glycolysis might explain functional improvement, whereas it seems unrelated to the protection on cell viability.
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Affiliation(s)
- M G Marina Prendes
- Cátedra de Fisiología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires and IQUIMEFA-CONICET, Buenos Aires, Argentina.
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Zhang L, Frederich M, He H, Balschi JA. Relationship between 5-aminoimidazole-4-carboxamide-ribotide and AMP-activated protein kinase activity in the perfused mouse heart. Am J Physiol Heart Circ Physiol 2005; 290:H1235-43. [PMID: 16258030 DOI: 10.1152/ajpheart.00906.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
AMP-activated protein kinase (AMPK) is a cellular energy sensor whose activity responds to AMP concentration ([AMP]). An agent that activates AMPK in cells is 5-aminoimidazole-4-carboxamide-1-riboside (AICA-riboside). Phosphorylated AICA-riboside or AICA-ribotide (ZMP) is an AMP analog. It is generally assumed that ZMP accumulation does not alter [AMP]. Additionally, the effect of AICA-riboside on AMPK activity of the heart is uncertain. Two hypotheses were tested in the isolated mouse heart: 1) sufficient ZMP concentration ([ZMP]) forms to increase AMPK activity, and 2) [ZMP] accumulation increases [AMP]. Perfusion of isolated mouse hearts with Krebs-Henseleit buffer containing 0.15-2 mM AICA-riboside concentration resulted in [ZMP] of 2-8 mM. ZMP accumulation reduced phosphocreatine concentration, which increased cytosolic [AMP]. In hearts with [ZMP] less than approximately 3 mM, in vivo AMPK allosteric activity effects of ZMP were observed; AMPK phosphorylation and [AMP] were not increased. With [ZMP] between 3 and 5 mM, in vitro AMPK activity and phosphorylation increased with unchanged [AMP]. This occurred in hearts perfused with 0.25 mM AICA-riboside for 48 min and 0.5 mM AICA-riboside for 24 min. The [ZMP] resulting in 50% AMPK activity (covalent phosphorylation of AMPK) was 4.1 +/- 0.6 mM. Hearts with [ZMP] >5 mM displayed increased [AMP] and AMPK activity that was not different from hearts with similar [AMP] with no [ZMP]; the half-maximal activity of AMP was 5.6 +/- 1.6 microM. Thus, in mouse hearts, AICA-riboside was metabolized to [ZMP] adequately to increase AMPK activity. Higher [ZMP] also increased cytosolic [AMP], which affects AMPK activity.
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Affiliation(s)
- Li Zhang
- NMR Laboratory for Physiological Chemistry, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
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Prueksaritanont T, Qiu Y, Mu L, Michel K, Brunner J, Richards KM, Lin JH. Interconversion pharmacokinetics of simvastatin and its hydroxy acid in dogs: effects of gemfibrozil. Pharm Res 2005; 22:1101-9. [PMID: 16028010 DOI: 10.1007/s11095-005-6037-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2005] [Accepted: 04/22/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE To characterize the pharmacokinetics of simvastatin (SV) and simvastatin acid (SVA), a lactone-acid pair known to undergo reversible metabolism, and to better understand mechanisms underlying pharmacokinetic interactions observed between SV and gemfibrozil. METHODS Pharmacokinetic studies were conducted after intravenous administration of SV and SVA to dogs pretreated with a vehicle or gemfibrozil. In vitro metabolism of SVA in dog hepatocytes as well as in vitro hepatic and plasma conversion of SV/SVA were investigated in the absence and presence of gemfibrozil. RESULTS In control animals, the irreversible elimination clearances of SV (CL10) and SVA (CL20) were 10.5 and 18.6 ml min(-1) kg(-1), respectively. The formation clearance of SVA from SV (CL12 = 4.8 ml min(-1) kg(-1)) was 8-fold greater than that of SV from SVA (CL21 = 0.6 ml min(-1) kg(-1)), and the recycled fraction was relatively minor (0.009). In gemfibrozil-treated animals, CL10 was essentially unchanged, whereas CL12, CL20, CL21, and recycled fraction were significantly decreased to 2.9, 9, 0.14 ml min(-1) kg(-1), and 0.003, respectively. In control dogs, values for real volume of distribution at steady state (Vss,real) of SV (2.3 L kg(-1)) were much larger than the corresponding values of SVA (0.3 L kg(-1)). Gemfibrozil treatment did not affect Vss,real of either SV or SVA. In dog hepatocytes, gemfibrozil modestly affected the formation of CYP3A-mediated oxidative metabolites (IC50 > 200 microM) and beta-oxidative products (IC5) approximately 100 microM), but markedly inhibited the glucuronidation-mediated lactonization of SVA and the glucuronidation of an SVA beta-oxidation product (IC50 = 18 microM). In in vitro dog and human liver S9 and plasma, hydrolysis of SV to SVA was much faster than that of SVA to SV. Gemfibrozil (250 microM) had a minimal inhibitory effect on the hydrolysis of either SV to SVA or SVA to SV in dog and human liver S9, but had a significant ( approximately 60%) inhibitory effect on the SV to SVA hydrolysis in both dog and human plasma. CONCLUSIONS In dogs, the interconversion process favored the formation of SVA and was less efficient than the irreversible elimination processes of SV and SVA. Treatment with gemfibrozil did not affect the distribution of SV/SVA, but rather affected the elimination of SVA and the SV/SVA interconversion processes. Gemfibrozil decreased CL20 and CL21 likely via its inhibitory effect on the glucuronidation of SVA, and not on the CYP3A-mediated oxidative metabolism of SV or SVA, the beta-oxidation of SVA, nor the SVA to SV hydrolysis. The decrease in CL12 might be due in part to the inhibitory effect of gemfibrozil on SV to SVA hydrolysis in plasma. Similar rationales may also be applicable to studies in humans and/or other statin lactone-acid pairs.
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Narayan SB, Boriack RL, Messmer B, Bennett MJ. Establishing a reference interval for measurement of flux through the mitochondrial fatty acid oxidation pathway in cultured skin fibroblasts. Clin Chem 2005; 51:644-6. [PMID: 15738519 DOI: 10.1373/clinchem.2004.045005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Srinivas B Narayan
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
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Frederich M, Zhang L, Balschi JA. Hypoxia and AMP independently regulate AMP-activated protein kinase activity in heart. Am J Physiol Heart Circ Physiol 2005; 288:H2412-21. [PMID: 15637122 DOI: 10.1152/ajpheart.00558.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hypothesis was tested that hypoxia increases AMP-activated protein kinase (AMPK) activity independently of AMP concentration ([AMP]) in heart. In isolated perfused rat hearts, cytosolic [AMP] was changed from 0.2 to 16 microM using metabolic inhibitors during both normal oxygenation (95% O2-5% CO2, normoxia) and limited oxygenation (95% N2-5% CO2, hypoxia). Total AMPK activity measured in vitro ranged from 2 to 40 pmol.min(-1).mg protein(-1) in normoxic hearts and from 5 to 55 pmol.min(-1).mg protein(-1) in hypoxic hearts. The dependence of the in vitro total AMPK activity on the in vivo cytosolic [AMP] was determined by fitting the measurements from individual hearts to a hyperbolic equation. The [AMP] resulting in half-maximal total AMPK activity (A0.5) was 3 +/- 1 microM for hypoxic hearts and 28 +/- 13 microM for normoxic hearts. The A0.5 for alpha2-isoform AMPK activity was 2 +/- 1 microM for hypoxic hearts and 13 +/- 8 microM for normoxic hearts. Total AMPK activity correlated with the phosphorylation of the Thr172 residue of the AMPK alpha-subunit. In potassium-arrested hearts perfused with variable O2 content, alpha-subunit Thr172 phosphorylation increased at O2 < or = 21% even though [AMP] was <0.3 microM. Thus hypoxia or O2 < or = 21% increased AMPK phosphorylation and activity independently of cytosolic [AMP]. The hypoxic increase in AMPK activity may result from either direct phosphorylation of Thr172 by an upstream kinase or reduction in the A0.5 for [AMP].
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Affiliation(s)
- Markus Frederich
- Nuclear Magnetic Resonance Laboratory for Physiological Chemistry, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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Pesenti C, Viani F. The Influence of Fluorinated Molecules (Semiochemicals and Enzyme Substrate Analogues) on the Insect Communication System. Chembiochem 2004; 5:590-613. [PMID: 15122631 DOI: 10.1002/cbic.200300829] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Can the introduction of fluorine atoms affect the bioactivity of natural semiochemicals? Can fluorine contribute in the creation of specific enzyme inhibitors to interrupt or disrupt the insect communication system? The first step for the bioactivity of a molecule is interaction with the biological sensor. Hydrogen and fluorine are almost bioisosteric and the receptor site of the enzyme can still recognize and accept the fluoro analogue of its natural substrate. However, the peculiar electronegativity of the fluorine atom can affect the binding, absorption, and transport of the molecule. The differences in the molecule's electronic properties can lead to differences in the chemical interactions between the receptor and the fluorinated substrate. Fluorine introduction can modify the metabolic stability and pathway of the semiochemicals in many different ways. Fluorinated analogues can show synergism, inhibition, or hyperagonism effects on insect behaviors, that is, the activity of the nonfluorinated parent compounds can be mimicked, lost, or increased. In any case, the fluorinated molecules can interact with the bioreceptors in a new and disrupting way. The semiochemicals are olfactory substances: fluorine can affect their volatility or smell. Production of semiochemicals from exogenous substances, perception at antennal receptors, and processing of biological responses are the main steps of communication among insects. In the production step, the fluorinated molecules can interact with enzymes that catalyze the biosynthesis of the natural pheromones. In the perception step, fluorinated semiochemicals can interact with the olfactory receptor cells; this often leads to totally unpredictable behaviors. Fluorinated molecules have been developed as probes to elucidate the complex chemorecognition processes of insects. Many of these molecules have been tested to find highly effective behavior-modifying chemicals. New analogues have been synthesized to investigate the metabolic pathway of a pheromone molecule and many of them are promising disrupting agents. Despite such titanic research efforts, the results have often been random, rational trends in the induced behaviors have sometimes been impossible to find, and practical applications of the fluorinated semiochemicals are still uncertain.
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Affiliation(s)
- Cristina Pesenti
- Istituto di Chimica per il Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mancinelli 7, 20131 Milano, Italy
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Jansen MA, Shen H, Zhang L, Wolkowicz PE, Balschi JA. Energy requirements for the Na+ gradient in the oxygenated isolated heart: effect of changing the free energy of ATP hydrolysis. Am J Physiol Heart Circ Physiol 2003; 285:H2437-45. [PMID: 12958035 DOI: 10.1152/ajpheart.00534.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study tests the hypothesis that a decrease of the free energy of ATP hydrolysis (Delta GATP) below a threshold value will inhibit Na+-K+-ATPase (Na+ pump) activity and result in an increase of intracellular Na+ concentration ([Na+]i) in the heart. Conditions were designed in which hearts were solely dependent on ATP derived from oxidative phosphorylation. The only substrate supplied was the fatty acid butyrate (Bu) at either low, 0.1 mM (LowBu), or high, 4 mM (HighBu), concentrations. Escalating work demand reduced the Delta GATP of the LowBu hearts. 31P, 23Na, and 87Rb NMR spectroscopy measured high-energy phosphate metabolites, [Na+]i, and Rb+ uptake. Rb+ uptake was used to estimate Na+ pump activity. To measure [Na+]i using a shift reagent for cations, extracellular Ca2+ was reduced to 0.85 mM, which eliminated work demand Delta GATP reductions. Increasing extracellular Na+ (Nae+) to 200 mM restored work demand Delta GATP reductions. In response to higher [Na+]e, [Na+]i increased equally in LowBu and HighBu hearts to approximately 8.6 mM, but Delta GATP decreased only in LowBu hearts. At lowest work demand the LowBu heart Delta GATP was -53 kJ/mol, Rb+ uptake was similar to that of HighBu hearts, and [Na+]i was constant. At highest work demand the LowBu heart Delta GATP decreased to -48 kJ/mol, the [Na+]i increased to 25 mM, and Rb+ uptake was 56% of that in HighBu hearts. At the highest work demand the HighBu heart Delta GATP was -54 kJ/mol and [Na+]i increased only approximately 10%. We conclude that a Delta GATP below -50 kJ/mol limits the Na+ pump and prevents maintenance of [Na+]i homeostasis.
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Affiliation(s)
- Maurits A Jansen
- Division of Cardiovascular Disease, Department o fMedicine, Universityof Alabama, Birmingham, 35294-4470, USA
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Adams DJ, Beveridge DJ, van der Weyden L, Mangs H, Leedman PJ, Morris BJ. HADHB, HuR, and CP1 bind to the distal 3'-untranslated region of human renin mRNA and differentially modulate renin expression. J Biol Chem 2003; 278:44894-903. [PMID: 12933794 DOI: 10.1074/jbc.m307782200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Production of renin is critically dependent on modulation of REN mRNA stability. Here we sought to elucidate the molecular mechanisms involved. Transfections of renin-expressing Calu-6 cells with reporter constructs showed that a cis-acting 34-nucleotide AU-rich "renin stability regulatory element" in the REN 3'-untranslated region (3'-UTR) contributes to basal REN mRNA instability. Yeast three-hybrid screening with the REN 3'-UTR as bait isolated HADHB (hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase (trifunctional protein) beta-subunit) as a novel REN mRNA-binding protein. Recombinant HADHB bound specifically to the 3'-UTR of REN mRNA, as did the known mRNA stabilizers HuR and CP1 (poly(C)-binding protein-1). This required the renin stability regulatory element. Forskolin, which augments REN mRNA stability in Calu-6 cells, increased binding of several proteins, including HuR and CP1, to the REN 3'-UTR, whereas 4-bromocrotonic acid, a specific thiolase inhibitor, decreased binding and elevated renin protein levels. Upon decreasing HADHB mRNA with RNA interference, renin protein and mRNA stability increased, whereas RNA interference against HuR caused these to decrease. Immunoprecipitation and reverse transcription-PCR of Calu-6 extracts confirmed that HADHB, HuR, and CP1 each associate with REN mRNA in vivo. Intracellular imaging revealed distinct localization of HADHB to mitochondria, HuR to nuclei, and CP1 throughout the cell. Immunohistochemistry demonstrated enrichment of HADHB in renin-producing renal juxtaglomerular cells. In conclusion, HADHB, HuR, and CP1 are novel REN mRNA-binding proteins that target a cis-element in the 3'-UTR of REN mRNA and regulate renin production. cAMP-mediated increased REN mRNA stability may involve stimulation of HuR and CP1, whereas REN mRNA decay may involve thiolase-dependent pathways.
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Affiliation(s)
- David J Adams
- Basic & Clinical Genomics Laboratory, School of Medical Sciences and Institute for Biomedical Research, The University of Sydney, New South Wales 2006, Australia
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Prueksaritanont T, Tang C, Qiu Y, Mu L, Subramanian R, Lin JH. Effects of fibrates on metabolism of statins in human hepatocytes. Drug Metab Dispos 2002; 30:1280-7. [PMID: 12386136 DOI: 10.1124/dmd.30.11.1280] [Citation(s) in RCA: 257] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study investigated the metabolic interaction between fibrates and statin hydroxy acids in human hepatocytes. Gemfibrozil (GFZ) modestly affected the formation of beta-oxidative products and CYP3A4-mediated oxidative metabolites of simvastatin hydroxy acid (SVA) but markedly inhibited the glucuronidation-mediated lactonization of SVA and the glucuronidation of a beta-oxidation product (IC(50) approximately 50 and 15 microM, respectively). In contrast, fenofibrate had a minimal effect on all the metabolic pathways of SVA. GFZ also significantly inhibited (IC(50) approximately 50-60 microM) the oxidation of cerivastatin (CVA) and rosuvastatin (RVA), but not of atorvastatin (AVA), while effectively decreasing (IC(50) approximately 30 to 60 microM) the lactonization of all three statins. As was observed previously with other statin hydroxy acids, RVA underwent significant glucuronidation to form an acyl glucuronide conjugate and lactonization to form RVA lactone in human liver microsomes and by UGT 1A1 and 1A3. While GFZ is not an inhibitor of CYP3A4, it is a competitive inhibitor (K(i) = 87 microM) of CYP2C8, a major catalyzing enzyme for CVA oxidation. These results suggest that 1) the pharmacokinetic interaction observed between GFZ and statins was not likely mediated by the inhibitory effect of GFZ on the beta-oxidation, but rather by its effect primarily on the glucuronidation and non-CYP3A-mediated oxidation of statin hydroxy acids, and 2) there is a potential difference between fibrates in their ability to affect the pharmacokinetics of statins, and among statins in their susceptibility to metabolic interactions with GFZ in humans.
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Abstract
The control of mitochondrial beta-oxidation, including the delivery of acyl moieties from the plasma membrane to the mitochondrion, is reviewed. Control of beta-oxidation flux appears to be largely at the level of entry of acyl groups to mitochondria, but is also dependent on substrate supply. CPTI has much of the control of hepatic beta-oxidation flux, and probably exerts high control in intact muscle because of the high concentration of malonyl-CoA in vivo. beta-Oxidation flux can also be controlled by the redox state of NAD/NADH and ETF/ETFH(2). Control by [acetyl-CoA]/[CoASH] may also be significant, but it is probably via export of acyl groups by carnitine acylcarnitine translocase and CPT II rather than via accumulation of 3-ketoacyl-CoA esters. The sharing of control between CPTI and other enzymes allows for flexible regulation of metabolism and the ability to rapidly adapt beta-oxidation flux to differing requirements in different tissues.
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Affiliation(s)
- Simon Eaton
- Surgery Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
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15
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Frederich M, Balschi JA. The relationship between AMP-activated protein kinase activity and AMP concentration in the isolated perfused rat heart. J Biol Chem 2002; 277:1928-32. [PMID: 11707445 DOI: 10.1074/jbc.m107128200] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The objective of this study was to define the relationship among AMP-activated protein kinase (AMPK) activity, AMP concentration ([AMP]), and [ATP] in perfused rat hearts. Bromo-octanoate, an inhibitor of beta-oxidation, and amino-oxyacetate, an inhibitor of the malate-aspartate shuttle, were used to modify substrate flux and thus increase cytosolic [AMP]. Cytosolic [AMP] was calculated using metabolites measured by (31)P NMR spectroscopy. Rat hearts were perfused with Krebs-Henseleit solution containing glucose and either no inhibitor, the inhibitors, or the inhibitors plus butyrate, a substrate that bypasses the metabolic blocks. In this way, [AMP] changed from 0.2 to 27.9 microm, and [ATP] varied between 11.7 and 6.8 mm. AMPK activity ranged from 7 to 60 pmol.min(-1).microg of protein(-1). The half-maximal AMPK activation (A(0.5)) was 1.8 +/- 0.3 microm AMP. Measurements in vitro have reported similar AMPK A(0.5) at 0.2 mm ATP, but found that A(0.5) increased 10-20-fold at 4 mm ATP. The low A(0.5) of this study despite a high [ATP] suggests that in vivo the ATP antagonism of AMPK activation is reduced, and/or other factors besides AMP activate AMPK in the heart.
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Affiliation(s)
- Markus Frederich
- NMR Laboratory for Physiological Chemistry, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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16
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Djouadi F, Weinheimer CJ, Saffitz JE, Pitchford C, Bastin J, Gonzalez FJ, Kelly DP. A gender-related defect in lipid metabolism and glucose homeostasis in peroxisome proliferator- activated receptor alpha- deficient mice. J Clin Invest 1998; 102:1083-91. [PMID: 9739042 PMCID: PMC509091 DOI: 10.1172/jci3949] [Citation(s) in RCA: 328] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The peroxisome proliferator-activated receptor alpha (PPARalpha) is a nuclear receptor implicated in the control of cellular lipid utilization. To test the hypothesis that PPARalpha is activated as a component of the cellular lipid homeostatic response, the expression of PPARalpha target genes was characterized in response to a perturbation in cellular lipid oxidative flux caused by pharmacologic inhibition of mitochondrial fatty acid import. Inhibition of fatty acid oxidative flux caused a feedback induction of PPARalpha target genes encoding fatty acid oxidation enzymes in liver and heart. In mice lacking PPARalpha (PPARalpha-/-), inhibition of cellular fatty acid flux caused massive hepatic and cardiac lipid accumulation, hypoglycemia, and death in 100% of male, but only 25% of female PPARalpha-/- mice. The metabolic phenotype of male PPARalpha-/- mice was rescued by a 2-wk pretreatment with beta-estradiol. These results demonstrate a pivotal role for PPARalpha in lipid and glucose homeostasis in vivo and implicate estrogen signaling pathways in the regulation of cardiac and hepatic lipid metabolism.
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Affiliation(s)
- F Djouadi
- INSERM U319, Université Paris 7, Paris, France
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17
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Intrasuksri U, Rangwala SM, O'Brien M, Noonan DJ, Feller DR. Mechanisms of peroxisome proliferation by perfluorooctanoic acid and endogenous fatty acids. GENERAL PHARMACOLOGY 1998; 31:187-97. [PMID: 9688458 DOI: 10.1016/s0306-3623(98)00029-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
1. The effects of endogenous fatty acids and perfluorooctanoic acid (PFOA) and its analogs on peroxisomal acyl CoA oxidase (ACO) and microsomal laurate hydroxylase (LH) activities were evaluated in primary cultures of rat hepatocytes and activation of peroxisome proliferator-activated receptor alpha (PPARalpha) in CV-1 cells. The rank order for the stimulation of ACO activity in hepatocytes for selected compounds was PFOA >> octanoic acid>octanedioic acid, perfluorooctanol (inactive). Increases in ACO activity by PFOA, like those of ciprofibrate, were associated with a marked increase in peroxisome number and cytosolic occupancy volume. Maximal effects of ciprofibrate and PFOA on the stimulation of ACO activity were not additive, suggesting that these two compounds share a common pathway of peroxisome proliferation. 2. Saturated monocarboxylic acids of C4 to C18 chain length were inactive, and, among dicarboxylic acids, only small elevations (40-45%) in ACO activity were observed with the long-chain C12 and C16 dioic acids. Of the C18 fatty acids tested, only oleic and linoleic acids, at 1 mM, produced a two- to three-fold elevation in ACO and LH activities. In comparison with endogenous fatty acids, PFOA was more potent and exhibited a different time course and greater magnitude of stimulation of ACO and LH activities in cultured hepatocytes. 3. Addition of mitochondrial beta-oxidation inhibitors (3-mercaptopropionic and 2-bromooctanoic acids) did not alter ACO activity in the presence of octanoic acid or octanedioic acid; nor did they modify the stimulation of ACO activity by PFOA. The carnitine palmitoyltransferase I inhibitor 2-bromopalmitic acid produced a 2.5-fold increase in ACO stimulatory activity and reduced both ciprofibrate- and PFOA-mediated stimulations of ACO activity. 4. Cycloheximide treatment reduced PFOA- and ciprofibrate-induced ACO activities; however, the response to oleic acid was not blocked and increased slightly. 5. In rat and human PPARalpha transactivation assays, the rank order of activation was ciprofibrate > PFOA > oleic acid > or = octanoic acid > octanedioic acid or perfluorooctanol (inactive). PFOA, ciprofibrate and oleic acid were activators of rPPARalpha at concentrations that correlated favorably with the changes in ACO activity in cell culture. Octanoic acid did not increase ACO activity and was a weak activator of PPARalpha. 6. Our findings suggest that fatty acids such as oleic acid (endogenous fatty acids) and PFOA (a stable fatty acid) act through more than one pathway to increase ACO activity in rat hepatocytes. We conclude that the potent effects of PFOA are primarily mediated by a mechanism that includes the activation of liver PPARalpha.
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Affiliation(s)
- U Intrasuksri
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus 43210, USA
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18
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Asaka N, Muranaka Y, Kirimoto T, Miyake H. Cardioprotective profile of MET-88, an inhibitor of carnitine synthesis, and insulin during hypoxia in isolated perfused rat hearts. Fundam Clin Pharmacol 1998; 12:158-63. [PMID: 9565769 DOI: 10.1111/j.1472-8206.1998.tb00936.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
3-(2,2,2-trimethylhydrazinium) propionate (MET-88) is an inhibitor of carnitine synthesis. This study was carried out to investigate whether or not reduction of carnitine content could attenuate hypoxic damage in isolated perfused rat hearts. Rats were divided into four groups: 1) vehicle control; 2) pretreatment with MET-88 (MET-88); 3) application of insulin (500 muU/mL) in the perfusate (insulin); and 4) pretreatment with MET-88 and application of insulin (MET-88 + insulin). MET-88 (100 mg/kg) was orally administered once a day for 10 days until the day before the experiments. Hearts were initially perfused for a 10 min period under normoxia, followed by a 30 min period under hypoxia. Hearts were frozen at the end of hypoxia for the measurement of high-energy phosphates, carnitine derivatives, and glycolysis intermediates. In a separate series of untreated and MET-88 treated hearts, exogenous glucose and palmitate oxidation was measured. MET-88 decreased the extent of the depression of cardiac contractility (+dP/dt), and aortic flow during the hypoxic state. Insulin also improved cardiac function, and co-treatment of MET-88 and insulin additionally improved cardiac function during hypoxia. MET-88 prevented the decrease of high-energy phosphate and the increase of long-chain acylcarnitine after 30 min of hypoxic perfusion. In addition, MET-88 increased the steady state of glucose oxidation in hypoxic perfused rat hearts. These results indicate that MET-88 has cardioprotective effects on contractile function and energy metabolism of isolated perfused rat hearts in a hypoxic condition. Preventing the accumulation of long-chain acylcarnitine may serve to protect hypoxic hearts.
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Affiliation(s)
- N Asaka
- Pharmacology Research Laboratory, Taiho Pharmaceutical Co Ltd, Tokushima, Japan
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19
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Qin YM, Haapalainen AM, Conry D, Cuebas DA, Hiltunen JK, Novikov DK. Recombinant 2-enoyl-CoA hydratase derived from rat peroxisomal multifunctional enzyme 2: role of the hydratase reaction in bile acid synthesis. Biochem J 1997; 328 ( Pt 2):377-82. [PMID: 9371691 PMCID: PMC1218931 DOI: 10.1042/bj3280377] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Rat liver peroxisomes contain two multifunctional enzymes: (1) perMFE-1 [2-enoyl-CoA hydratase 1/Delta3,Delta2-enoyl-CoA isomerase/(S)-3-hydroxyacyl-CoA dehydrogenase] and (2) perMFE-2 [2-enoyl-CoA hydratase 2/(R)-3-hydroxyacyl-CoA dehydrogenase]. To investigate the role of the hydratase activity of perMFE-2 in beta-oxidation, a truncated version of perMFE-2 was expressed in Escherichia coli as a recombinant protein. The protein catalyses the hydration of straight-chain (2E)-enoyl-CoAs to (3R)-hydroxyacyl-CoAs, but it is devoid of hydratase 1 [(2E)-enoyl-CoA to (3S)-hydroxyacyl-CoA] and (3R)-hydroxyacyl-CoA dehydrogenase activities. The purified enzyme (46 kDa hydratase 2) can be stored as an active enzyme for at least half a year. The recombinant enzyme hydrates (24E)-3alpha,7alpha,12alpha-trihydroxy- 5beta-cholest-24-enoyl-CoA to (24R,25R)-3alpha,7alpha,12alpha, 24-tetrahydroxy-5beta-cholestanoyl-CoA, which has previously been characterized as a physiological intermediate in bile acid synthesis. The stereochemistry of the products indicates that the hydration reaction catalysed by the enzyme proceeds via a syn mechanism. A monofunctional 2-enoyl-CoA hydratase 2 has not been observed as a wild-type protein. The recombinant 46 kDa hydratase 2 described here survives in a purified form under storage, thus being the first protein of this type amenable to application as a tool in metabolic studies.
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Affiliation(s)
- Y M Qin
- Biocenter Oulu, University of Oulu, Linnanmaa, FIN-90570 Oulu, Finland
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20
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Ostretsova IB, Nikiforov AA. Weak organic acid uptake in rat renal tubules in vitro: stimulation by pent-4-enoic acid. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART C, PHARMACOLOGY, TOXICOLOGY & ENDOCRINOLOGY 1997; 117:1-6. [PMID: 9185322 DOI: 10.1016/s0742-8413(96)00200-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A hypoglycemic agent, pent-4-enoic acid (4-PA; 0.1-1.0 mM), stimulated baseline uptake of a weak organic anion, fluorescein, in superficial proximal tubules of rat kidney and inhibited the rate of glucose production from pyruvate (but not lactate or endogenous substrates) by rat renal cortex fragment suspension. The stimulation of the fluorescein uptake was not observed in a low Na+ medium. Maleate (0.1-1.0 mM) and Cd2+ (0.1 mM), known similarly to 4-PA to induce the renal Fanconi syndrome, also stimulated the fluorescein uptake in the Na-dependent manner. Both 4-PA and Cd2+ and maleate elevated intracellular content of alpha-ketoglutarate and increased ammonia formation from endogenous substrates in the suspension of the rat renal cortex fragments. The stimulatory effects of 4-PA, maleate and Cd2+ on the fluorescein uptake were markedly attenuated by LiCl (5 mM), suggesting that the Na-coupled re-uptake of alpha-ketoglutarate is involved in energization of the fluorescein uptake in the exchange for the cytoplasmic dicarboxylate.
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Affiliation(s)
- I B Ostretsova
- Laboratory of Comparative Physiology and Biochemistry of Tissue Barriers, Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
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21
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Affiliation(s)
- P A Watkins
- Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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22
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Fong JC, Leu SJ, Chai SP. Differential inhibition of lipolysis by 2-bromopalmitic acid and 4-bromocrotonic acid in 3T3-L1 adipocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1344:65-73. [PMID: 9022756 DOI: 10.1016/s0005-2760(96)00133-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Two inhibitors of fatty acid oxidation, 2-bromopalmitic acid (Br-C16) and 4-bromocrotonic acid (Br-C4) were examined for their effect on lipolysis in 3T3-L1 adipocytes. Both agents inhibited in a dose-dependent manner the rate of oxidation of exogenously added [1-14C]palmitate with similar time-courses, reaching a plateau at 3-9 h. While Br-C16 at 50 microM and 100 microM inhibited palmitate oxidation by approximately 40% and 60%, respectively, pretreatment with both concentrations inhibited lipolysis in washed cells in an almost identical manner. The magnitude of inhibition increased with time of pretreatment. On the other hand, like inhibition of fatty acid oxidation, inhibition of lipolysis by Br-C4 pretreatment was dose-dependent with maximal inhibition reached after 3 h pretreatment. The finding that isoproterenol- and dibutyryl cAMP-stimulated lipolysis were similarly suppressed by either Br-C4 or Br-C16 pretreatment, suggesting that a step distal to cAMP formation was involved. In addition, while the inhibitory effect of Br-C16 was not significantly influenced, the inhibition of lipolysis caused by Br-C4 was attenuated by pretreating cells with crotonic acid, octanoate, or palmitate. The longer chain-length of the fatty acids the cells were exposed, the stronger attenuation of the inhibition caused by Br-C4 was observed. Moreover, whereas pretreatment with Br-C16 was without effect, pretreatment with Br-C4 significantly decreased hormone-sensitive lipase (HSL) activity in cell extracts, albeit to an extent much smaller than its inhibitory effect on lipolysis. In conclusion, these results indicate that irreversible inhibition of lipolysis by Br-C16 or Br-C4 cannot be attributed to their effect on fatty acid oxidation. Some factor capable of modulating HSL activity seems to be involved.
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Affiliation(s)
- J C Fong
- Institute of Biochemistry, National Yang-Ming University, Taipei, Taiwan, ROC
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23
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Bosch MP, Pérez R, Lahuerta G, Hernanz D, Camps F, Guerrero A. Difluoropalmitic acids as potential inhibitors of the biosynthesis of the sex pheromone of the Egyptian armyworm Spodoptera littoralis--IV. Bioorg Med Chem 1996; 4:467-72. [PMID: 8733628 DOI: 10.1016/0968-0896(96)00027-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
2,2-, 3,3- and 4,4-Difluoropalmitic acids (1-3) have been synthesized and fully characterized. Acids 2 and 3 were prepared through fluorination of the corresponding dithioacetal-protected ketoesters followed by enzymatic saponification. The acids 1-3 were evaluated in vivo as inhibitors of the beta-oxidation step of the biosynthesis of (Z,E)-9,11-tetradecadienyl acetate, the major component of the sex pheromone of the Egyptian armyworm Spodoptera littoralis. Only, the 2,2- and 3,3-derivatives, i.e. those containing the two fluorine atoms at the positions involved in the chain-shortened step, have been found to be active, the activity being similar to or lower than that displayed by the corresponding monofluorinated acids.
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Affiliation(s)
- M P Bosch
- Department of Technology of Tensioactives, C.I.D. (CSIC), Barcelona, Spain
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24
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Schulz H. Oxidation of fatty acids. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0167-7306(08)60510-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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25
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Docosahexaenoic acid synthesis in human skin fibroblasts involves peroxisomal retroconversion of tetracosahexaenoic acid. J Lipid Res 1995. [DOI: 10.1016/s0022-2275(20)39724-8] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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26
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Carregal M, Varela A, Dalamon V, Sacks S, Savino EA. Beneficial effects of oxfenicine on the hypoxic rat atria. Arch Physiol Biochem 1995; 103:45-9. [PMID: 8574776 DOI: 10.3109/13813459509007562] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
During hypoxia the isolated rat atria released lactate into the bathing medium and underwent a rise of resting tension and a decline of the peak developed tension and pacemaker frequency. The atria from 24 h fasted rats, which oxidize faster their endogenous triacylglycerol pool, showed greater functional disturbances during hypoxia and a smaller recovery after reoxygenation than those from fed rats. Oxfenicine, which is a selective inhibitor of carnitine palmitoyltransferase I, attenuated the rise of resting tension and improved the post-hypoxic recovery of peak tension in the atria from fasted rats. The decline of the pacemaker frequency as well as the lactate output were not altered by the inhibitor. Present data show that oxfenicine ameliorated some of the hypoxic functional disturbances. Inasmuch lactate output did not change and these effects manifested only in the atria predisposed to the utilization of endogenous lipids, it may be inferred that oxfenicine preserved the atrial functions through the inhibition of fatty acid oxidation.
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Affiliation(s)
- M Carregal
- Cátedra de Fisiología, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina
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27
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Gordon J, Broekemeier K, Spector A, Pfeiffer D. Mitochondrial metabolism of 12- and 15-hydroxyeicosatetraenoic acids. J Lipid Res 1994. [DOI: 10.1016/s0022-2275(20)41184-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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28
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Abstract
Coenzyme A (CoASH) has a clearly defined role as a cofactor for a number of oxidative and biosynthetic reactions in intermediary metabolism. Formation of acyl-CoA thioesters from organic carboxylic acids activates the acid for further biotransformation reactions and facilitates enzyme recognition. Xenobiotic carboxylic acids can also form CoA-thioesters, and the resulting acyl-CoA may contribute to the compound's toxicity. Generation of an unusual or poorly-metabolized acyl-CoA from a xenobiotic may lead to cellular metabolic dysfunction through several types of mechanisms including: (1) inhibition of key metabolic enzymes by the acyl-CoA; (2) sequestration of the total cellular CoA pool as the unusual acyl-CoA; (3) physical-chemical effects of the acyl-CoA; and (4) sequestration and depletion of carnitine as the acyl group is transformed from the acyl-CoA to form the corresponding acylcarnitine. Many of these toxicities are similar to sequelae observed in the inherited organic acidurias in which endogenously-generated acyl-CoAs accumulate secondary to an enzymopathy. Insights into the cellular mechanisms of xenobiotic acyl-CoA accumulation have been derived from model systems developed to understand organic acidemias, such as the methylmalonyl-CoA accumulation of the methylmalonic acidurias. The relevance of acyl-CoA accretion to human pathophysiology has now been well established, and identification of the relevant mechanism of toxicity can allow implementation of strategies to minimize the metabolic injury. Additionally, recognition of the potential for acyl-CoA mediated xenobiotic injury should result in improved rational drug design and earlier recognition of such toxicity when it develops.
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Affiliation(s)
- E P Brass
- Department of Medicine, Case Western Reserve University, Cleveland, OH 44106-4981
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29
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Yao KW, Mao LF, Luo MJ, Schulz H. The relationship between mitochondrial activation and toxicity of some substituted carboxylic acids. Chem Biol Interact 1994; 90:225-34. [PMID: 8168171 DOI: 10.1016/0009-2797(94)90012-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The activation of 4-bromocrotonic acid, 4-bromo-2-octenoic acid, valproic acid, and 3-methylglycidic acid by conversion to their CoA thioesters and the effects of these carboxylic acids on palmitoylcarnitine-supported respiration were studied with rat liver and rat heart mitochondria. 4-Bromocrotonic acid was activated by both liver and heart mitochondria, whereas 4-bromo-2-octenoic acid and valproic acid were only activated by liver mitochondria. 3-Methylglycidic acid was not a substrate of mitochondrial activation. All of the carboxylic acids that were activated also inhibited palmitoylcarnitine-supported respiration. 3-Methylglycidoyl-CoA was found to irreversibly inhibit 3-ketoacyl-CoA thiolase in a concentration-dependent and time-dependent manner. Together, these results lead to the conclusion that substituted medium-chain carboxylic acids, which enter mitochondria directly, may inhibit beta-oxidation as long as they are activated and perhaps further metabolized in the mitochondrial matrix to compounds that sequester CoA and/or inhibit beta-oxidation enzymes. Liver is more susceptible to inhibition by such xenobiotic carboxylic acids due to the broader substrate specificity of its mitochondrial medium-chain acyl-CoA synthetase (EC 6.2.1.2).
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Affiliation(s)
- K W Yao
- Department of Chemistry, City College of the City University of New York, NY 10031
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30
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Varela A, Carregal M, Espósito S, Bruno-Magnasco C, Savino EA. Effects of oxfenicine on the atria from fed and fasted rats. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE, DE BIOCHIMIE ET DE BIOPHYSIQUE 1994; 102:125-8. [PMID: 7519459 DOI: 10.3109/13813459408996119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The aim of the investigation was to assess whether endogenous triacylglycerol contributes to the maintenance of the atrial functions. To attain this information, the atria from fed and fasted rats were treated with oxfenicine which is a cardioselective inhibitor of carnitine palmitoyltransferase I. In the presence of glucose, oxfenicine suppressed lipolysis without affecting the pacemaker and contractile activities. When exposed to 2-deoxyglucose in a substrate-free medium, the atria displayed a progressive fall of the contractile strength and pacemaker rate. The dysfunctions appeared faster in the atria from fed rats coinciding with a smaller triacylglycerol mobilization. Under this condition, oxfenicine abolished the triacylglycerol breakdown, increased the fall in the peak tension, elicited a rise in the resting tension and accelerated the decline of the pacemaker rate, leading in a significant number of atria to a complete cessation of the spontaneous contractions. These effects proceeded faster in the fed rats atria. Present data suggest that glucose oxidation is sufficient to meet the atrial energy demand when the fatty acid catabolism is impeded. The noxious effects of oxfenicine, attained after the glucose metabolism was eliminated, lend direct evidence to the notion that endogenous triacylglycerol supports, at least partly, the atrial functions.
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Affiliation(s)
- A Varela
- Cátedra de Fisiología, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina
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31
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Gordon J, Heller S, Kaduce T, Spector A. Formation and release of a peroxisome-dependent arachidonic acid metabolite by human skin fibroblasts. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)41749-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Affiliation(s)
- U Diczfalusy
- Department of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden
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33
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Kaikaus RM, Sui Z, Lysenko N, Wu NY, Ortiz de Montellano PR, Ockner RK, Bass NM. Regulation of pathways of extramitochondrial fatty acid oxidation and liver fatty acid-binding protein by long-chain monocarboxylic fatty acids in hepatocytes. Effect of inhibition of carnitine palmitoyltransferase I. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74191-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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34
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Alpert SE, Walenga RW. Human tracheal epithelial cells selectively incorporate 15-hydroxyeicosatetraenoic acid into phosphatidylinositol. Am J Respir Cell Mol Biol 1993; 8:273-81. [PMID: 8448017 DOI: 10.1165/ajrcmb/8.3.273] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
15-hydroxyeicosatetraenoic acid (15-HETE) is the major lipoxygenase metabolite of arachidonic acid produced by human airway epithelial cells. Because HETEs have been shown to be rapidly metabolized and/or incorporated into cellular lipids in other cell types, we investigated the uptake, metabolism, and intracellular distribution of exogenous 15-HETE by primary monolayer cultures of human tracheal epithelial (HTE) cells. At concentrations of 0.1 microM, [3H]15-HETE was rapidly incorporated by HTE cells and also metabolized primarily by beta-oxidation to several more polar products that were released extracellularly. The majority of cell-associated [3H]15-HETE radiolabel was distributed into phospholipids, with phosphatidylinositol (PI) accounting for approximately 75% of phospholipid radiolabel. Exogenous 5- and 12-HETE were also metabolized by HTE cells but were less extensively incorporated into phospholipids and were distributed primarily into phosphatidylcholine and phosphatidylethanolamine. Phospholipase A2 hydrolysis indicated selective esterification of unmodified 15-HETE to the sn-2 position of phospholipids. 15-HETE incorporation into total phospholipids and into PI was saturable (half maximal incorporation at 0.82 and 0.68 microM, respectively), while incorporation into neutral lipids continued to increase at concentrations of 15-HETE up to 5 microM. The incorporation of 15-HETE into PI was metabolically stable, with an intracellular half-life of 12 h, and was not subject to mobilization in response to 5 microM calcium ionophore A23187. HTE cells can incorporate and metabolize HETEs that the cells themselves produce as well as those that might be released by inflammatory cells recruited into the airway.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S E Alpert
- Pediatric Pulmonary Division, Rainbow Babies and Childrens Hospital, Case Western Reserve University, Cleveland, Ohio 44106
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35
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Camps F, Hospital S, Rosell G, Delgado A, Guerrero A. Synthesis of biosynthetic inhibitors of the sex pheromone of Spodoptera littoralis. Part II: Acetylenic and cyclopropane fatty acids. Chem Phys Lipids 1992; 61:157-67. [PMID: 1511488 DOI: 10.1016/0009-3084(92)90008-d] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The synthesis of new acetylenic and cyclopropane fatty acids, as potential inhibitors of the beta-oxidation step in the proposed biosynthesis of the sex pheromone of the Egyptian armyworm Spodoptera littoralis, is reported. The biological activity of the compounds has been determined by in vitro and in vivo bioassays, and among all the compounds tested, dichlorocyclopropane acid has shown the highest inhibition activity displayed so far.
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Affiliation(s)
- F Camps
- Department of Biological Organic Chemistry, CID (CSIC), Barcelona, Spain
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36
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Rainsford KD. Mechanisms of rash formation and related skin conditions induced by non-steroidal anti-inflammatory drugs. SIDE-EFFECTS OF ANTI-INFLAMMATORY DRUGS 3 1992. [DOI: 10.1007/978-94-011-2982-4_34] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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37
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Abdel-Aleem S, Youssef J, Frangakis C, Badr M. Selective inhibition of hepatic peroxisomal fatty acid beta-oxidation by enoximone. Life Sci 1992; 51:53-7. [PMID: 1535408 DOI: 10.1016/0024-3205(92)90218-e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although beta-oxidation of fatty acids occurs in both peroxisomes and mitochondria, beta-oxidizing enzymes in these organelles have distinct differences in their specifity and sensitivity to inhibitors. In this study, the effects of the phosphodiesterase inhibitor enoximone on hepatic peroxisomal and mitochondrial beta-oxidation were investigated. In liver homogenates from control rats, cyanide-insensitive peroxisomal beta-oxidation of palmitoyl-CoA was inhibited progressively by increasing concentrations of enoximone. Similar results were obtained in liver homogenates from rats pretreated with the known peroxisomal proliferator diethylhexylphthalate. In contrast, mitochondrial beta-oxidation of palmitoyl-CoA was not inhibited by enoximone. These data show that enoximone selectively inhibits basal as well as induced peroxisomal, but not mitochondrial, beta-oxidation of the CoA thioester of long-chain fatty acids. The availability of specific inhibitors of peroxisomal beta-oxidation should prove useful in elucidating regulatory mechanisms operative in this pathway in normal as well as in proliferated peroxisomes.
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Affiliation(s)
- S Abdel-Aleem
- Glaxo Research Institute, Glaxo Inc. Research Triangle Park, NC 27709
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38
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Tserng KY, Jin SJ, Hoppel CL. Spiropentaneacetic acid as a specific inhibitor of medium-chain acyl-CoA dehydrogenase. Biochemistry 1991; 30:10755-60. [PMID: 1931995 DOI: 10.1021/bi00108a021] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To study the structure-activity relationship between pentanoic acid analogues and the inhibition of fatty acid oxidation, a number of 4-pentenoic and methylenecyclopropaneacetic acid derivatives were prepared. All compounds inhibited palmitoylcarnitine oxidation in rat liver mitochondria, with 50% inhibition occurring at a concentration between 6 and 100 microM. However, only methylenecyclopropaneacetic acid (MCPA) and spiropentaneacetic acid (SPA) showed in vivo inhibitory activity in rats as indicated by the occurrence of dicarboxylic aciduria. Rats treated with SPA excreted metabolites derived only from fatty acid oxidation whereas MCPA-treated rats also excreted metabolites derived from branch-chained amino acid and lysine metabolism. SPA is a specific inhibitor of fatty acid oxidation without affecting amino acid metabolism. The site of inhibition is medium-chain acyl-CoA dehydrogenase (MCAD). In contrast, MCPA inhibited both MCAD and short-chain acyl-CoA dehydrogenase with a stronger inhibition toward the latter. The inhibition of fatty acid oxidation by both inhibitors was partially reversible by glycine or l-carnitine. Since SPA does not form a ring-opened nucleophile such as that proposed for MCPA in the inhibition of FAD prosthetic group in acyl-CoA dehydrogenases, we propose that the irreversible inhibition by SPA occurs by a tight complex without forming a covalent bond to the isoalloxazine ring in FAD.
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Affiliation(s)
- K Y Tserng
- Research Service, Department of Veterans Affairs (VA) Medical Center, Cleveland, Ohio 44106
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39
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Synthesis of potential inhibitors of the biosynthesis of the sex pheromone of Spodoptera littoralis. Part I: Monofluorinated fatty acids. Chem Phys Lipids 1991. [DOI: 10.1016/0009-3084(91)90002-s] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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40
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41
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Mathur SN, Albright E, Field FJ. 12-Hydroxyeicosatetraenoic acid is metabolized by beta-oxidation in mouse peritoneal macrophages. Identification of products and proposed pathway. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45325-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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42
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Roediger WE, Nance S. Selective reduction of fatty acid oxidation in colonocytes: correlation with ulcerative colitis. Lipids 1990; 25:646-52. [PMID: 2127822 DOI: 10.1007/bf02536016] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Attempts were made to define which fatty acid (2:0 to 18:1) was optimally oxidized by isolated colonocytes (colonic epithelial cells) and to select inhibitors of fatty acid oxidation which would be analogous in their action to the inhibition of fatty acid oxidation observed in colonocytes involved with ulcerative colitis. Isolated colonic epithelial cells of Sprague-Dawley rats were used with 2-mercaptoacetate, dichloroacetate, 3-mercaptopropionate, 4-mercaptobutyrate, 4-sulfatebutyrate, 2-bromobutyrate, sulfite ions and nitrite ions. n-Butyrate (4:0) was maximally oxidized to CO2 and ketone bodies (mean value 5.46 mumols/min/g dry wt). Oxidation of butyrate to CO2 was diminished by 2-bromobutyrate, sulfite ions and all mercapto fatty acids. Both fatty acid oxidation and glucose oxidation were significantly inhibited by 2-bromobutyrate, while mercapto fatty acids and sulfite inhibited fatty acid oxidation (p less than 0.01) without significantly changing glucose oxidation. Observation with 2-mercaptoacetate and sulfite correlate with early changes of fatty acid oxidation observed in cases of ulcerative colitis, and warrant further study with isolated colonocytes of man.
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Affiliation(s)
- W E Roediger
- Department of Surgery, Queen Elizabeth Hospital, Australia
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43
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Moore SA, Yoder E, Spector AA. Role of the blood-brain barrier in the formation of long-chain omega-3 and omega-6 fatty acids from essential fatty acid precursors. J Neurochem 1990; 55:391-402. [PMID: 2115069 DOI: 10.1111/j.1471-4159.1990.tb04150.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Elongated, more highly polyunsaturated derivatives of linoleic acid (18:2 omega-6) and linolenic acid (18:3 omega-3) accumulate in brain, but their sites of synthesis and mechanism of entry are not well characterized. To investigate the role of the blood-brain barrier in this process, cultured murine cerebromicrovascular endothelia were incubated with [1-14C]18:2 omega-6 or [1-14C]18:3 omega-3 and their elongation/desaturation products determined. The major metabolite of 18:2 omega-6 was 20:4 omega-6, whereas the primary product from 18:3 omega-3 was 20:5 omega-3. Although these products were found primarily in cell lipids, they were also released from the cells and gradually accumulated in the extracellular fluid. Eicosanoid production was observed from the 20:4 omega-6 and 20:5 omega-3 that were formed. No 22:5 omega-6 or 22:6 omega-3 fatty acids were detected, suggesting that these endothelial cells are not the site of the final desaturation step. Although the uptake of 18:3 omega-3 and 18:2 omega-6 was nearly identical, 18:3 omega-3 was more extensively elongated and desaturated. Competition experiments demonstrated a preference for 18:3 omega-3 by the elongation/desaturation pathway. These findings suggest that the blood-brain barrier can play an important role in the elongation and desaturation of omega-3 and omega-6 essential fatty acids during their transfer from the circulation into the brain.
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Affiliation(s)
- S A Moore
- Department of Pathology, University of Iowa, Iowa City 52242
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44
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A Role for Malonyl-CoA in Glucose-Stimulated Insulin Secretion from Clonal Pancreatic β-Cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(20)88227-1] [Citation(s) in RCA: 199] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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45
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Varela A, Lanzetta D, Savino EA. The effects of 4-pentenoic and pentanoic acid on the hypoxic rat atria. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1989; 97:375-80. [PMID: 2480093 DOI: 10.3109/13813458909104550] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
When exposed to hypoxia, the isolated rat atria released lactate into the bathing medium and underwent a rise in resting tension and a decline of the contractions frequency. In some of them, it also occurred a complete cessation of the pacemaker activity. Atria from 24-h fasted rats, when compared to those from fed ones, exhibited a lower lactate output, a higher rise in resting tension, a faster decay of the contraction frequency and an increased occurrence of atrial arrest. In both the fed and fasted rats atria, some triacylglycerol lipolysis remained throughout the hypoxic incubation. Addition of 2 mM 4-pentenoic acid abolished the lipolytic activity and reduced lactate output in both groups of atria. In the fed rats atria it also accelerated the decrease of the pacemaker frequency. Pentanoic acid reduced lactate output in both groups of atria and in those from fed rats it did not alter lipolysis but increased the rise in resting tension, the decline of the pacemaker frequency and the occurrence of atrial arrest. Present data indicate that although 4-pentenoic acid inhibits fatty acid oxidation and endogenous lipolysis, it was not able to reduce the noxious effects of hypoxia. Since the effects of 4-pentenoic acid were rather similar to those of fasting and pentanoic acid, they might be ascribed to the accumulation of its own oxidative metabolites which could be detrimental for the hypoxic atria.
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Affiliation(s)
- A Varela
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina
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46
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Gordon JA, Figard PH, Spector AA. Identification of the major metabolite of 12-HETE produced by renal tubular epithelial cells. J Lipid Res 1989. [DOI: 10.1016/s0022-2275(20)38332-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Van Rafelghem MJ, Vanden Heuvel JP, Menahan LA, Peterson RE. Perfluorodecanoic acid and lipid metabolism in the rat. Lipids 1988; 23:671-8. [PMID: 3419281 DOI: 10.1007/bf02535666] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Alterations in lipid metabolism were examined in adult male Sprague-Dawley rats seven days after a single intraperitoneal injection of perfluorodecanoic acid (PFDA; 20, 40 or 80 mg/kg). Because PFDA treatment caused a dose-related reduction in feed intake, the response of vehicle-treated rats pair-fed to those receiving PFDA was monitored to distinguish direct effects of the perfluorinated fatty acid from those secondary to hypophagia. Carcass content of lipid phosphorus and free cholesterol decreased in dose-dependent fashion in both PFDA-treated and pair-fed rats. Carcass triacylglycerols diminished in a similar manner, yet PFDA-treated rats at each dose had a higher concentration of neutral acylglycerols than their vehicle-treated, pair-fed counterparts. In vehicle-treated, pair-fed rats at the 80 mg/kg dose level, lipid phosphorus and free cholesterol as a proportion of carcass fat increased, whereas the share of the triacylglycerols declined. Because of the higher concentration of triacylglycerols in the carcass of rats treated with 80 mg/kg PFDA, enrichment of lipid phosphorus and free cholesterol in carcass fat was less than in their pair-fed partners. The amount of lipid phosphorus and free cholesterol per hepatocyte was similar in both PFDA-treated rats and their pair-fed partners. Liver triacylglycerols were markedly increased in PFDA-treated rats. A similar but less extensive augmentary effect of PFDA on hepatic esterified cholesterol was found. Concentration of triacylglycerols in plasma was not elevated in PFDA-treated rats, in spite of hepatic accumulation of esterified compounds. Also, the plasma level of free fatty acids and 3-hydroxybutyrate was similar in all treatment groups, including those receiving PFDA.(ABSTRACT TRUNCATED AT 250 WORDS)
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Yen TT. MTP-1307, a novel antidiabetic agent, improves the glucose intolerance of viable yellow obese-diabetic mice. Life Sci 1987; 41:2349-54. [PMID: 3683081 DOI: 10.1016/0024-3205(87)90658-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
MTP-1307 is an oral antidiabetic agent with a unique profile. It improves the glucose intolerance of viable yellow obese-diabetic mice at 25 mg/kg whereas at 300 mg/kg, it only marginally lowers the basal glucose levels of the same mice. This selective activity on exogenous glucose makes MTP-1307 potentially a useful agent to treat postprandial glucose intolerance without causing hypoglycemia.
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Affiliation(s)
- T T Yen
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285
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