1
|
The aminopeptidase B (Ap-B) is phosphorylated in HEK293 cells. Biochimie 2022; 201:204-212. [PMID: 35952945 DOI: 10.1016/j.biochi.2022.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 11/22/2022]
Abstract
Proteolysis is a post-translational modification (PTM) that affects the whole proteome. First regarded as only destructive, it is more precise than expected. It is finely regulated by other PTMs like phosphorylation. Aminopeptidase B (Ap-B), a M1 metallopeptidase, hydrolyses the peptide bond on the carbonyl side of basic residues at the NH2-terminus of peptides. 2D electrophoresis (2DE) was used to show that Ap-B is modified by phosphorylation. Detection of Ap-B by western blot after 2DE reveals several isoforms with different isoelectric points. Using alkaline phosphatase, Pro-Q Diamond phosphorylation-specific dye and kinase-specific inhibitors, we confirmed that Ap-B is phosphorylated. Phosphorylation can alter the structure of proteins leading to changes in their activity, localization, stability and association with other interacting molecules. We showed that Ap-B phosphorylation might delay its turnover. Our study illustrates the central role of the crosstalk between kinases and proteases in the regulation of many biological processes.
Collapse
|
2
|
Hijioka M, Anan J, Ishibashi H, Kurauchi Y, Hisatsune A, Seki T, Koga T, Yokomizo T, Shimizu T, Katsuki H. Inhibition of Leukotriene B4 Action Mitigates Intracerebral Hemorrhage-Associated Pathological Events in Mice. J Pharmacol Exp Ther 2016; 360:399-408. [DOI: 10.1124/jpet.116.238824] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 12/28/2016] [Indexed: 01/30/2023] Open
|
3
|
Jeffery CJ. Protein species and moonlighting proteins: Very small changes in a protein's covalent structure can change its biochemical function. J Proteomics 2015; 134:19-24. [PMID: 26455812 DOI: 10.1016/j.jprot.2015.10.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 09/23/2015] [Accepted: 10/01/2015] [Indexed: 02/03/2023]
Abstract
UNLABELLED In the past few decades, hundreds of moonlighting proteins have been identified that perform two or more distinct and physiologically relevant biochemical or biophysical functions that are not due to gene fusions, multiple RNA splice variants, or pleiotropic effects. For this special issue on protein species, this article discusses three topics related to moonlighting proteins that illustrate how small changes or differences in protein covalent structures can result in different functions. Examples are given of moonlighting proteins that switch between functions after undergoing post-translational modifications (PTMs), proteins that share high levels of amino acid sequence identity to a moonlighting protein but share only one of its functions, and several "neomorphic moonlighting proteins" in which a single amino acid mutation results in the addition of a new function. BIOLOGICAL SIGNIFICANCE For this special issue on protein species, this article discusses three topics related to moonlighting proteins : Post-translational modifications (PTMs) that can cause a switch between functions, homologs that share only one of multiple functions, and proteins in which a single amino acid mutation results in the creation of a new function. The examples included illustrate that even in an average protein of hundreds of amino acids, a relatively small difference in sequence or PTMs can result in a large difference in function, which can be important in predicting protein functions, regulation of protein functions, and in the evolution of new functions.
Collapse
Affiliation(s)
- Constance J Jeffery
- Dept. Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA; University of Illinois at Chicago, Dept. Biological Sciences, MC567, 900 S. Ashland Ave., Chicago, IL 60607, USA.
| |
Collapse
|
4
|
Sacerdoti D, Pesce P, Di Pascoli M, Brocco S, Cecchetto L, Bolognesi M. Arachidonic acid metabolites and endothelial dysfunction of portal hypertension. Prostaglandins Other Lipid Mediat 2015; 120:80-90. [PMID: 26072731 DOI: 10.1016/j.prostaglandins.2015.05.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/20/2015] [Accepted: 05/25/2015] [Indexed: 12/12/2022]
Abstract
Increased resistance to portal flow and increased portal inflow due to mesenteric vasodilatation represent the main factors causing portal hypertension in cirrhosis. Endothelial cell dysfunction, defined as an imbalance between the synthesis, release, and effect of endothelial mediators of vascular tone, inflammation, thrombosis, and angiogenesis, plays a major role in the increase of resistance in portal circulation, in the decrease in the mesenteric one, in the development of collateral circulation. Reduced response to vasodilators in liver sinusoids and increased response in the mesenteric arterioles, and, viceversa, increased response to vasoconstrictors in the portal-sinusoidal circulation and decreased response in the mesenteric arterioles are also relevant to the pathophysiology of portal hypertension. Arachidonic acid (AA) metabolites through the three pathways, cyclooxygenase (COX), lipoxygenase, and cytochrome P450 monooxygenase and epoxygenase, are involved in endothelial dysfunction of portal hypertension. Increased thromboxane-A2 production by liver sinusoidal endothelial cells (LSECs) via increased COX-1 activity/expression, increased leukotriens, increased epoxyeicosatrienoic acids (EETs) (dilators of the peripheral arterial circulation, but vasoconstrictors of the portal-sinusoidal circulation), represent a major component in the increased portal resistance, in the decreased portal response to vasodilators and in the hyper-response to vasoconstrictors. Increased prostacyclin (PGI2) via COX-1 and COX-2 overexpression, and increased EETs/heme-oxygenase-1/K channels/gap junctions (endothelial derived hyperpolarizing factor system) play a major role in mesenteric vasodilatation, hyporeactivity to vasoconstrictors, and hyper-response to vasodilators. EETs, mediators of liver regeneration after hepatectomy and of angiogenesis, may play a role in the development of regenerative nodules and collateral circulation, through stimulation of vascular endothelial growth factor (VEGF) inside the liver and in the portal circulation. Pharmacological manipulation of AA metabolites may be beneficial for cirrhotic portal hypertension.
Collapse
Affiliation(s)
- David Sacerdoti
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy.
| | - Paola Pesce
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Marco Di Pascoli
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Silvia Brocco
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Lara Cecchetto
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Massimo Bolognesi
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| |
Collapse
|
5
|
Influence of Plum ( Prunus Mume Siebold and Zucc.) Products on Growth Performance, Intestinal Function and Immunity in Broiler Chicks. J Poult Sci 2013. [DOI: 10.2141/jpsa.0120028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
6
|
Juchem G, Weiss DR, Knott M, Senftl A, Förch S, Fischlein T, Kreuzer E, Reichart B, Laufer S, Nees S. Regulation of coronary venular barrier function by blood borne inflammatory mediators and pharmacological tools: insights from novel microvascular wall models. Am J Physiol Heart Circ Physiol 2012; 302:H567-81. [DOI: 10.1152/ajpheart.00360.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that postcapillary venules play a central role in the control of the tightness of the coronary system as a whole, particularly under inflammatory conditions. Sandwich cultures of endothelial cells and pericytes of precapillary arteriolar or postcapillary venular origin from human myocardium as models of the respective vascular walls (sandwich cultures of precapillary arteriolar or postcapillary venular origin) were exposed to thrombin and components of the acutely activatable inflammatory system, and their hydraulic conductivity ( LP) was registered. LP of SC-PAO remained low under all conditions (3.24 ± 0.52·10−8cm·s−1·cmH2O−1). In contrast, in the venular wall model, PGE2, platelet-activating factor (PAF), leukotriene B4 (LTB4), IL-6, and IL-8 induced a prompt, concentration-dependent, up to 10-fold increase in LP with synergistic support when combined. PAF and LTB4 released by metabolically cooperating platelets, and polymorphonuclear leucocytes (PMNs) caused selectively venular endothelial cells to contract and to open their clefts widely. This breakdown of the barrier function was preventable and even reversible within 6–8 h by the presence of 50 μM quercetin glucuronide (QG). LTB4 synthesis was facilitated by biochemical involvement of erythrocytes. Platelets segregated in the arterioles and PMNs in the venules of blood-perfused human myocardium (histological studies on donor hearts refused for heart transplantation). Extrapolating these findings to the coronary microcirculation in vivo would imply that the latter's complex functionality after accumulation of blood borne inflammatory mediators can change rapidly due to selective breakdown of the postcapillary venular barrier. The resulting inflammatory edema and venulo-thrombosis will severely impair myocardial performance. The protection afforded by QG could be of particular relevance in the context of cardiosurgical intervention.
Collapse
Affiliation(s)
- Gerd Juchem
- Department of Cardiac Surgery, University of Munich (Ludwig Maximilians University), Munich
| | - Dominik R. Weiss
- Department of Transfusion Medicine and Hemostaseology, University of Erlangen-Nuremberg (Friedrich Alexander University), Erlangen
| | - Maria Knott
- Department of Physiology, University of Munich (Ludwig Maximilians University), Munich
| | - Anton Senftl
- Department of Physiology, University of Munich (Ludwig Maximilians University), Munich
| | - Stefan Förch
- Department of Physiology, University of Munich (Ludwig Maximilians University), Munich
| | - Theodor Fischlein
- Department of Cardiac Surgery, Hospital Nuremberg South, Nuremberg; and
| | - Eckart Kreuzer
- Department of Cardiac Surgery, University of Munich (Ludwig Maximilians University), Munich
| | - Bruno Reichart
- Department of Cardiac Surgery, University of Munich (Ludwig Maximilians University), Munich
| | - Stefan Laufer
- Department of Pharmaceutical Chemistry, University of Tuebingen (Eberhard Karls University), Munich, Germany
| | - Stephan Nees
- Department of Physiology, University of Munich (Ludwig Maximilians University), Munich
| |
Collapse
|
7
|
Lee CY, Lim JW, Ko YH, Kang SY, Park MJ, Ko TG, Lee JH, Hyun Y, Jeong KS, Jang IS. Intestinal Growth and Development of Weanling Pigs in Response to Dietary Supplementation of Antibiotics, Phytogenic Products and Brewer's Yeast plus Bacillus Spores. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2011. [DOI: 10.5187/jast.2011.53.3.227] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
8
|
Affiliation(s)
- Motonao Nakamura
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Tokyo, Japan.
| | | |
Collapse
|
9
|
Effects of a Blend of Prunus Mume Extract as an Alternative to Antibiotics on Growth Performance, Activity of Digestive Enzymes and Microflora Population in Broiler Chickens. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2007. [DOI: 10.5187/jast.2007.49.5.611] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
10
|
Kim D, Kim S, Yu D, Kang G, Kim J, Kang H, Jang B, Na J, Suh O, Jang I, Lee K. Effects of Single or Mixed Supplements of Plant Extract, Fermented Medicinal Plants and Lactobacillus on Growth Performance in Broilers. ACTA ACUST UNITED AC 2007. [DOI: 10.5536/kjps.2007.34.3.187] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
11
|
Jang I, Ko Y, Kang S, Lee C. Effect of a commercial essential oil on growth performance, digestive enzyme activity and intestinal microflora population in broiler chickens. Anim Feed Sci Technol 2007. [DOI: 10.1016/j.anifeedsci.2006.06.009] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
12
|
Luo M, Flamand N, Brock TG. Metabolism of arachidonic acid to eicosanoids within the nucleus. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:618-25. [PMID: 16574479 DOI: 10.1016/j.bbalip.2006.02.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 02/20/2006] [Accepted: 02/20/2006] [Indexed: 11/18/2022]
Abstract
The eicosanoids are a diverse family of molecules that have powerful effects on cell function. They are best known as intercellular messengers, having autocrine and paracrine effects following their secretion from the cells that synthesize them. Many of the eicosanoids are produced from one polyunsaturated fatty acid, arachidonic acid. The diversity of possible products that can be synthesized from arachidonic acid is due, in part to the variety of enzymes that can act on it. Over the past 15 years, studies have placed many, but not all, of these enzymes at or inside the nucleus. In some cases, the nuclear import or export of arachidonic acid-processing enzymes is highly regulated. Furthermore, nuclear receptors that are activated by specific eicosanoids are known to exist. Taken together, these findings indicate that the enzymatic conversion of arachidonic acid to specific signaling molecules can occur in the nucleus, that it is regulated, and that the synthesized products may act within the nucleus. The objectives of this commentary are to review what is known about the metabolism of arachidonic acid to eicosanoids within the nucleus and to point to important areas for future discovery.
Collapse
Affiliation(s)
- Ming Luo
- Department of Internal Medicine, University of Michigan Health System, 6301 MSRB III, Ann Arbor, MI 48109-0642, USA
| | | | | |
Collapse
|
13
|
Newman JW, Morisseau C, Hammock BD. Epoxide hydrolases: their roles and interactions with lipid metabolism. Prog Lipid Res 2005; 44:1-51. [PMID: 15748653 DOI: 10.1016/j.plipres.2004.10.001] [Citation(s) in RCA: 320] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The epoxide hydrolases (EHs) are enzymes present in all living organisms, which transform epoxide containing lipids by the addition of water. In plants and animals, many of these lipid substrates have potent biologically activities, such as host defenses, control of development, regulation of inflammation and blood pressure. Thus the EHs have important and diverse biological roles with profound effects on the physiological state of the host organisms. Currently, seven distinct epoxide hydrolase sub-types are recognized in higher organisms. These include the plant soluble EHs, the mammalian soluble epoxide hydrolase, the hepoxilin hydrolase, leukotriene A4 hydrolase, the microsomal epoxide hydrolase, and the insect juvenile hormone epoxide hydrolase. While our understanding of these enzymes has progressed at different rates, here we discuss the current state of knowledge for each of these enzymes, along with a distillation of our current understanding of their endogenous roles. By reviewing the entire enzyme class together, both commonalities and discrepancies in our understanding are highlighted and important directions for future research pertaining to these enzymes are indicated.
Collapse
Affiliation(s)
- John W Newman
- Department of Entomology, UCDavis Cancer Center, University of California, One Shields Avenue, Davis, CA 95616, USA
| | | | | |
Collapse
|
14
|
Haeggström JZ. Leukotriene A4 hydrolase/aminopeptidase, the gatekeeper of chemotactic leukotriene B4 biosynthesis. J Biol Chem 2004; 279:50639-42. [PMID: 15339917 DOI: 10.1074/jbc.r400027200] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Jesper Z Haeggström
- Department of Medical Biochemistry and Biophysics, Division of Chemistry 2, Karolinska Institutet, S-171 77 Stockholm, Sweden.
| |
Collapse
|
15
|
Zhang YY, Walker JL, Huang A, Keaney JF, Clish CB, Serhan CN, Loscalzo J. Expression of 5-lipoxygenase in pulmonary artery endothelial cells. Biochem J 2002; 361:267-76. [PMID: 11772398 PMCID: PMC1222306 DOI: 10.1042/0264-6021:3610267] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Increased expression of 5-lipoxygenase (5LO) in pulmonary artery endothelial cells (PAECs) has been observed in disease states such as pulmonary hypertension and allergen challenge. To understand the function of endothelial 5LO, we examined the expression of this enzyme in normally cultured human PAECs and its characteristics when overexpressed. A small amount of 5LO message and protein was detected by reverse-transcriptase-mediated PCR (RT-PCR) and Western blotting in PAECs. Sequencing of the RT-PCR products that overlapped the entire coding region of 5LO mRNA indicated that the sequence of PAEC 5LO was identical with that of leucocyte 5LO. Incubation of the PAECs with A23187 and arachidonic acid led to a small production of 5-hydroxyeicosatetraenoic acid (5-HETE) (46-98 pmol/4x10(6) cells) but no leukotrienes. Overexpression of 5LO in PAECs by adenovirus-mediated gene transfer revealed that the enzyme was localized in the nucleus. Incubation of the transduced cells with A23187 (5 microM) caused the production of both 5LO products and downstream leukotrienes. The proportions of the produced leukotriene A(4) (LTA(4)) hydrolates (sum of 6-trans-LTB(4) and 12-epi-6-trans-LTB(4)), LTB(4) and cysteinyl leukotriene were approx. 17:14:10. cGMP production in the 5LO-transduced PAECs was decreased by 33+/-14% on stimulation with A23187. These results show that cultured PAECs express a minimal amount of 5LO, which can generate some 5-HETE, but not leukotrienes. However, increased expression of 5LO in PAECs can lead to the production of all downstream leukotrienes, which could potentially cause endothelial dysfunction in the pulmonary vasculature.
Collapse
Affiliation(s)
- Ying-Yi Zhang
- Whitaker Cardiovascular Institute, and Evans Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA.
| | | | | | | | | | | | | |
Collapse
|
16
|
Brock TG, Maydanski E, McNish RW, Peters-Golden M. Co-localization of leukotriene a4 hydrolase with 5-lipoxygenase in nuclei of alveolar macrophages and rat basophilic leukemia cells but not neutrophils. J Biol Chem 2001; 276:35071-7. [PMID: 11451962 DOI: 10.1074/jbc.m105676200] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The synthesis of leukotriene B(4) from arachidonic acid requires the sequential action of two enzymes: 5-lipoxygenase and leukotriene A(4) hydrolase. 5-Lipoxygenase is known to be present in the cytoplasm of some leukocytes and able to accumulate in the nucleoplasm of others. In this study, we asked if leukotriene A(4) hydrolase co-localizes with 5-lipoxygenase in different types of leukocytes. Examination of rat basophilic leukemia cells by both immunocytochemistry and immunofluorescence revealed that leukotriene A(4) hydrolase, like 5-lipoxygenase, was most abundant in the nucleus, with only minor occurrences in the cytoplasm. The finding of abundant leukotriene A(4) hydrolase in the soluble nuclear fraction was substantiated by two different cell fractionation techniques. Leukotriene A(4) hydrolase was also found to accumulate together with 5-lipoxygenase in the nucleus of alveolar macrophages. This result was obtained using both in situ and ex vivo techniques. In contrast to these results, peripheral blood neutrophils contained both leukotriene A(4) hydrolase and 5-lipoxygenase exclusively in the cytoplasm. After adherence of neutrophils, 5-lipoxygenase was rapidly imported into the nucleus, whereas leukotriene A(4) hydrolase remained cytosolic. Similarly, 5-lipoxygenase was localized in the nucleus of neutrophils recruited into inflamed appendix tissue, whereas leukotriene A(4) hydrolase remained cytosolic. These results demonstrate for the first time that leukotriene A(4) hydrolase can be accumulated in the nucleus, where it co-localizes with 5-lipoxygenase. As with 5-lipoxygenase, the subcellular distribution of leukotriene A(4) hydrolase is cell-specific and dynamic, but differences in the mechanisms regulating nuclear import must exist. The degree to which these two enzymes are co-localized may influence their metabolic coupling in the conversion of arachidonic acid to leukotriene B(4).
Collapse
Affiliation(s)
- T G Brock
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Michigan Health System, Ann Arbor, Michigan 48109-0642, USA.
| | | | | | | |
Collapse
|
17
|
Abstract
Leukotriene B4 (LTB4) is known as one of the most potent chemoattractants and activators of leukocytes and is involved in inflammatory diseases. Enzymes involved in the biosynthesis and metabolism of LTB4 have been cloned, and their properties are well understood. Two G-protein-coupled receptors (BLT1 and BLT2) have been cloned and characterized. BLT1 and BLT2 are high- and low-affinity LTB4 receptors, respectively, and form a gene cluster in human and mouse. In this article recent findings on the metabolism of and the receptors for LTB4 are reviewed. We also discuss briefly a coreceptor role of BLT in HIV infection, and ion channel modification by LTB4.
Collapse
Affiliation(s)
- T Yokomizo
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, CREST of Japan, Science and Technology Corporation.
| | | | | |
Collapse
|
18
|
Abstract
Epoxides are organic three-membered oxygen compounds that arise from oxidative metabolism of endogenous, as well as xenobiotic compounds via chemical and enzymatic oxidation processes, including the cytochrome P450 monooxygenase system. The resultant epoxides are typically unstable in aqueous environments and chemically reactive. In the case of xenobiotics and certain endogenous substances, epoxide intermediates have been implicated as ultimate mutagenic and carcinogenic initiators Adams et al. (Chem. Biol. Interact. 95 (1995) 57-77) Guengrich (Properties and Metabolic roles 4 (1982) 5-30) Sayer et al. (J. Biol. Chem. 260 (1985) 1630-1640). Therefore, it is of vital importance for the biological organism to regulate levels of these reactive species. The epoxide hydrolases (E.C. 3.3.2. 3) belong to a sub-category of a broad group of hydrolytic enzymes that include esterases, proteases, dehalogenases, and lipases Beetham et al. (DNA Cell Biol. 14 (1995) 61-71). In particular, the epoxide hydrolases are a class of proteins that catalyze the hydration of chemically reactive epoxides to their corresponding dihydrodiol products. Simple epoxides are hydrated to their corresponding vicinal dihydrodiols, and arene oxides to trans-dihydrodiols. In general, this hydration leads to more stable and less reactive intermediates, however exceptions do exist. In mammalian species, there are at least five epoxide hydrolase forms, microsomal cholesterol 5,6-oxide hydrolase, hepoxilin A(3) hydrolase, leukotriene A(4) hydrolase, soluble, and microsomal epoxide hydrolase. Each of these enzymes is distinct chemically and immunologically. Table 1 illustrates some general properties for each of these classes of hydrolases. Fig. 1 provides an overview of selected model substrates for each class of epoxide hydrolase.
Collapse
Affiliation(s)
- A J Fretland
- Department of Environmental Health,of Washington, 4225 Roosevelt Way NE, #100 Seattle, WA 98105-6099, USA
| | | |
Collapse
|
19
|
Haeggström JZ. Leukotriene A4 hydrolase and the committed step in leukotriene B4 biosynthesis. Clin Rev Allergy Immunol 1999; 17:111-31. [PMID: 10436862 DOI: 10.1007/bf02737600] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- J Z Haeggström
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
20
|
Rybina IV, Feinmark SJ. Alteration of human leukotriene A4 hydrolase activity after site-directed mutagenesis: serine-415 is a regulatory residue. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1438:199-203. [PMID: 10320802 DOI: 10.1016/s1388-1981(99)00046-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Leukotriene A4 hydrolase (LTA-H) is a bifunctional protein that has aminopeptidase activity, but also contains an epoxide hydrolase activity that converts leukotriene (LT)A4 to LTB4. The lipid metabolic activity of this enzyme plays a central role in the control of polymorphonuclear leukocyte function and in the development of inflammation. LTA-H is widely spread in many mammalian tissues, although it appears to be inactive in many cases. Regulation of this enzyme's activity by phosphorylation of a serine at residue 415 has recently been described. Since the activation of LTA-H in the presence of activated PMNL would likely lead to a substantial increase in the production of inflammatory lipids, regulation of LTA-H presents a novel potential target for anti-inflammatory therapy. We have now made a series of site-directed mutants at this site to test the importance of this residue to the activity of LTA-H. Replacement of the critical serine with threonine or glutamine has little effect on either the epoxide hydrolase or aminopeptidase activities. However, replacing serine with a negatively charged amino acid (either aspartate or glutamate), intended to mimic phosphorylation at that site, causes significant reduction in epoxide hydrolase activity (50-70%). These mutations have little effect on the aminopeptidase activity of the LTA-H, suggesting that the mutation models the regulatory event and is not simply due to improper folding of the protein.
Collapse
Affiliation(s)
- I V Rybina
- Department of Pharmacology, Columbia University, 630 West 168th Street, New York, NY 10032, USA
| | | |
Collapse
|
21
|
Gupta N, Nicholson DW, Ford-Hutchinson AW. Demonstration of cell-specific phosphorylation of LTC4 synthase. FEBS Lett 1999; 449:66-70. [PMID: 10225430 DOI: 10.1016/s0014-5793(99)00397-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PMA-induced leukotriene C4 synthase (LTC4S) phosphorylation was investigated over a period of 8 h in a monocytic cell line (THP-1). The level of LTC4S phosphorylation was increased 3-5 fold over a 4 h period decreasing to basal levels after 8 h. This phosphorylation event was found to be specific to THP-1 cells as there was a lack of LTC4S phosphorylation in both COS-7 and K-562 cells, and was also found to be dependent on the cellular confluency. In the presence of specific protein kinase C (PKC) inhibitors, a dose-dependent inhibition of the phosphorylation of LTC4S became evident, an effect not seen with PKA and tyrosine kinase inhibitors. This represents the first direct demonstration of LTC4S phosphorylation in whole cells.
Collapse
Affiliation(s)
- N Gupta
- Merck Frosst Centre for Therapeutic Research, Pointe Claire-Dorval, Que., Canada.
| | | | | |
Collapse
|