1
|
Sarparast M, Pourmand E, Hinman J, Vonarx D, Reason T, Zhang F, Paithankar S, Chen B, Borhan B, Watts JL, Alan J, Lee KSS. Dihydroxy-Metabolites of Dihomo-γ-linolenic Acid Drive Ferroptosis-Mediated Neurodegeneration. ACS CENTRAL SCIENCE 2023; 9:870-882. [PMID: 37252355 PMCID: PMC10214511 DOI: 10.1021/acscentsci.3c00052] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Indexed: 05/31/2023]
Abstract
Even after decades of research, the mechanism of neurodegeneration remains understudied, hindering the discovery of effective treatments for neurodegenerative diseases. Recent reports suggest that ferroptosis could be a novel therapeutic target for neurodegenerative diseases. While polyunsaturated fatty acid (PUFA) plays an important role in neurodegeneration and ferroptosis, how PUFAs may trigger these processes remains largely unknown. PUFA metabolites from cytochrome P450 and epoxide hydrolase metabolic pathways may modulate neurodegeneration. Here, we test the hypothesis that specific PUFAs regulate neurodegeneration through the action of their downstream metabolites by affecting ferroptosis. We find that the PUFA dihomo-γ-linolenic acid (DGLA) specifically induces ferroptosis-mediated neurodegeneration in dopaminergic neurons. Using synthetic chemical probes, targeted metabolomics, and genetic mutants, we show that DGLA triggers neurodegeneration upon conversion to dihydroxyeicosadienoic acid through the action of CYP-EH (CYP, cytochrome P450; EH, epoxide hydrolase), representing a new class of lipid metabolites that induce neurodegeneration via ferroptosis.
Collapse
Affiliation(s)
- Morteza Sarparast
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Elham Pourmand
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Jennifer Hinman
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Derek Vonarx
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Tommy Reason
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Fan Zhang
- Department
of Pharmacology and Toxicology, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Shreya Paithankar
- Department
of Pediatrics and Human Development, Michigan
State University, Grand Rapids, Michigan 49503, United States
| | - Bin Chen
- Department
of Pharmacology and Toxicology, Michigan
State University, East Lansing, Michigan 48824, United States
- Department
of Pediatrics and Human Development, Michigan
State University, Grand Rapids, Michigan 49503, United States
| | - Babak Borhan
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Jennifer L. Watts
- School
of Molecular Biosciences, Washington State
University, Pullman, Washington 99164, United States
| | - Jamie Alan
- Department
of Pharmacology and Toxicology, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Kin Sing Stephen Lee
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
- Department
of Pharmacology and Toxicology, Michigan
State University, East Lansing, Michigan 48824, United States
| |
Collapse
|
2
|
Sarparast M, Pourmand E, Hinman J, Vonarx D, Reason T, Zhang F, Paithankar S, Chen B, Borhan B, Watts JL, Alan J, Lee KSS. Dihydroxy-Metabolites of Dihomo-gamma-linolenic Acid Drive Ferroptosis-Mediated Neurodegeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.05.522933. [PMID: 36711920 PMCID: PMC9881903 DOI: 10.1101/2023.01.05.522933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Even after decades of research, the mechanism of neurodegeneration remains understudied, hindering the discovery of effective treatments for neurodegenerative diseases. Recent reports suggest that ferroptosis could be a novel therapeutic target for neurodegenerative diseases. While polyunsaturated fatty acid (PUFA) plays an important role in neurodegeneration and ferroptosis, how PUFAs may trigger these processes remains largely unknown. PUFA metabolites from cytochrome P450 and epoxide hydrolase metabolic pathways may modulate neurodegeneration. Here, we test the hypothesis that specific PUFAs regulate neurodegeneration through the action of their downstream metabolites by affecting ferroptosis. We find that the PUFA, dihomo gamma linolenic acid (DGLA), specifically induces ferroptosis-mediated neurodegeneration in dopaminergic neurons. Using synthetic chemical probes, targeted metabolomics, and genetic mutants, we show that DGLA triggers neurodegeneration upon conversion to dihydroxyeicosadienoic acid through the action of CYP-EH, representing a new class of lipid metabolite that induces neurodegeneration via ferroptosis.
Collapse
Affiliation(s)
- Morteza Sarparast
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Elham Pourmand
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Jennifer Hinman
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Derek Vonarx
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Tommy Reason
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Fan Zhang
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - Shreya Paithankar
- Department of Pediatrics and Human Development, Michigan State University, Grand Rapids, MI, USA
| | - Bin Chen
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA,Department of Pediatrics and Human Development, Michigan State University, Grand Rapids, MI, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Jennifer L. Watts
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA
| | - Jamie Alan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA,Corresponding Authors
| | - Kin Sing Stephen Lee
- Department of Chemistry, Michigan State University, East Lansing, MI, USA,Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA,Corresponding Authors
| |
Collapse
|
3
|
Barnych B, Rand AA, Cajka T, Lee KSS, Hammock BD. Synthesis of cyclooxygenase metabolites of 8,9-epoxyeicosatrienoic acid (EET): 11- and 15-hydroxy 8,9-EETs. Org Biomol Chem 2018; 15:4308-4313. [PMID: 28470279 DOI: 10.1039/c7ob00789b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
COX metabolites of 8,9-EET, previously observed as potent mitogenic lipid mediators, were synthesized for the first time by using two synthetic approaches. These synthetic materials allow for structural confirmation of COX metabolites of 8,9-EET and further study of their biological roles.
Collapse
Affiliation(s)
- Bogdan Barnych
- Departments of Entomology and Nematology and UC Davis Comprehensive Cancer Center, University of California Davis, One Shields Avenue, Davis, California 95616, USA.
| | | | | | | | | |
Collapse
|
4
|
Ueberbacher BT, Oberdorfer G, Gruber K, Faber K. Epoxide-hydrolase-initiated hydrolysis/rearrangement cascade of a methylene-interrupted bis-epoxide yields chiral THF moieties without involvement of a "cyclase". Chembiochem 2009; 10:1697-704. [PMID: 19496106 DOI: 10.1002/cbic.200900176] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In contrast with electrophilic enzyme-catalysed cyclisations in terpenoid biosynthesis, cyclisations of tetrahydrofuran moieties found in several groups of natural products, such as annonaceous acetogenins, neurofurans and phytooxylipins, appear to proceed through a nucleophilic cascade mechanism starting from bis-epoxy fatty acid precursors. This hypothesis was verified by epoxide-hydrolase-catalysed hydrolytic ring-opening/cyclisation cascades starting from a methylene-interrupted meso-bis-epoxide model substrate, which furnished the corresponding THF products with excellent de and ee values. Molecular modelling showed that the points of enzyme attack were consistent with the stereospecificities of the enzymes, whereas the stereochemical courses of the cyclisation were solely governed by Baldwin's rules and did not invoke the involvements of a "cyclase".
Collapse
Affiliation(s)
- Barbara T Ueberbacher
- Department of Chemistry, Organic and Bioorganic Chemistry, University of Graz, Heinrichstrasse 28, Graz, Austria
| | | | | | | |
Collapse
|
5
|
Falck JR, Reddy LM, Byun K, Campbell WB, Yi XY. Epoxygenase eicosanoids: synthesis of tetrahydrofuran-diol metabolites and their vasoactivity. Bioorg Med Chem Lett 2007; 17:2634-8. [PMID: 17293113 PMCID: PMC1950572 DOI: 10.1016/j.bmcl.2007.01.096] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 01/27/2007] [Accepted: 01/30/2007] [Indexed: 12/30/2022]
Abstract
Eight members of a recently identified family of tetrahydrofuran-diols (THFDs), originating from epoxyeicosatrienoic acids (EETs), were prepared stereospecifically from D-(+)-glucose. The THFDs potently induced relaxation of pre-contracted bovine arteries.
Collapse
Affiliation(s)
- J R Falck
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | | | | | | | | |
Collapse
|
6
|
Markaverich BM, Alejandro M, Thompson T, Mani S, Reyna A, Portillo W, Sharp J, Turk J, Crowley JR. Tetrahydrofurandiols (THF-diols), leukotoxindiols (LTX-diols), and endocrine disruption in rats. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:702-8. [PMID: 17520056 PMCID: PMC1868002 DOI: 10.1289/ehp.9311] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Accepted: 01/29/2007] [Indexed: 05/11/2023]
Abstract
BACKGROUND Ground corncob animal bedding and corn food products contain substances that disrupt endocrine function in rats. The disruptors were identified as isomeric mixtures of tetrahydrofurandiols (THF-diols; 9,12-oxy-10,13-dihydroxyoctadecanoic acid and 10,13-oxy-9,12-dihydroxyoctadecanoic acid) and leukotoxindiols (LTX-diols; 9,10-dihydroxy-12-octadecenoic acid and 12,13-dihydroxy-9-octadecenoic acid). The authentic compounds blocked sexual behavior in male rats and estrous cyclicity in female rats at oral doses of 2 ppm. OBJECTIVES To define the lowest observed adverse effect level (LOAEL) for the THF-diols and LTX-diols in rats, we examined the nature of their interaction (additive or synergistic) and quantified the concentration of THF-diols in rat tissues. METHODS Adult male and female rats were provided drinking solutions containing various doses of THF-diols and/or LTX-diols, and we evaluated their effects on male sexual behavior and female estrous cyclicity. Tissues were collected for THF-diol determination by gas chromatography-mass spectrometry. RESULTS The LOAEL for THF-diols and LTX-diols for blocking estrous cyclicity was 0.5-1.0 ppm and 0.2-0.5 ppm, respectively. Higher concentrations (1-2 ppm) of THF-diols were required to block male sexual behavior. Combination studies with subthreshold doses of 0.05 ppm THF-diols plus 0.05 ppm LTX-diols revealed that their effects on estrous cyclicity were not synergistic. We were unable to detect THF-diols in tissues from rats treated with 10 ppm of the compounds, suggesting that metabolism may be involved. DISCUSSION THF-diols, LTX-diols, and/or their metabolites likely act additively to disrupt endocrine function in male and female rats at concentrations (0.5-1 ppm) that are 200-fold lower than those of classical phytoestrogen endocrine disruptors.
Collapse
Affiliation(s)
- Barry M Markaverich
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Preparation of fatty amide polyols via
epoxidation of vegetable oil amides by oat seed peroxygenase. J AM OIL CHEM SOC 2005. [DOI: 10.1007/s11746-005-1097-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
8
|
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
|
9
|
Piazza GJ, Nuñez A, Foglia TA. Hydrolysis of mono- and diepoxyoctadecanoates by alumina. J AM OIL CHEM SOC 2003. [DOI: 10.1007/s11746-003-0792-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- George J. Piazza
- ; Eastern Regional Research Center; USDA, ARS; 600 E. Mermaid Lane 19038 Wyndmoor Pennsylvania
| | - Alberto Nuñez
- ; Eastern Regional Research Center; USDA, ARS; 600 E. Mermaid Lane 19038 Wyndmoor Pennsylvania
| | - Thomas A. Foglia
- ; Eastern Regional Research Center; USDA, ARS; 600 E. Mermaid Lane 19038 Wyndmoor Pennsylvania
| |
Collapse
|
10
|
Biosynthesis of tetrahydrofuranyl fatty acids from linoleic acid by clavibacter
sp. ALA2. J AM OIL CHEM SOC 2003. [DOI: 10.1007/s11746-003-0667-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
11
|
Markaverich BM, Alejandro MA, Markaverich D, Zitzow L, Casajuna N, Camarao N, Hill J, Bhirdo K, Faith R, Turk J, Crowley JR. Identification of an endocrine disrupting agent from corn with mitogenic activity. Biochem Biophys Res Commun 2002; 291:692-700. [PMID: 11855846 DOI: 10.1006/bbrc.2002.6499] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A mitogenic agent in corncob bedding and fresh corn products disrupts sexual behavior and estrous cyclicity in rats. The mitogenic activity resides in an isomeric mixture of linoleic acid derivatives with a tetrahydrofuran ring and two hydroxyl groups (THF-diols) that include 9, (12)-oxy-10,13-dihydroxystearic acid and 10, (13)-oxy-9,12-dihydroxystearic acid. Synthetic THF-diols stimulated breast cancer cell proliferation in vitro and disrupted the estrous cycle in female rats at oral doses of approximately 0.30 mg/kg body weight/day. Exposure to THF-diols may disrupt endocrine function in experimental animals at doses approximately 200 times lower than classical phytoestrogens, promote proliferation of breast or prostate cancer, and adversely affect human health.
Collapse
Affiliation(s)
- Barry M Markaverich
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Weijers CA, de Bont JA. Epoxide hydrolases from yeasts and other sources: versatile tools in biocatalysis. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s1381-1177(98)00123-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
13
|
Andberg MB, Hamberg M, Haeggström JZ. Mutation of tyrosine 383 in leukotriene A4 hydrolase allows conversion of leukotriene A4 into 5S,6S-dihydroxy-7,9-trans-11,14-cis-eicosatetraenoic acid. Implications for the epoxide hydrolase mechanism. J Biol Chem 1997; 272:23057-63. [PMID: 9287304 DOI: 10.1074/jbc.272.37.23057] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Leukotriene A4 hydrolase is a bifunctional zinc metalloenzyme that catalyzes the final step in the biosynthesis of the proinflammatory mediator leukotriene B4. In previous studies with site-directed mutagenesis on mouse leukotriene A4 hydrolase, we have identified Tyr-383 as a catalytic amino acid involved in the peptidase reaction. Further characterization of the mutants in position 383 revealed that [Y383H], [Y383F], and [Y383Q] leukotriene A4 hydrolases catalyzed hydrolysis of leukotriene A4 into a novel enzymatic metabolite. From analysis by high performance liquid chromatography, gas chromatography/mass spectrometry of material generated in the presence of H216O or H218O, steric analysis of the hydroxyl groups, treatment with soybean lipoxygenase, and comparison with a synthetic standard, the novel metabolite was assigned the structure 5S, 6S-dihydroxy-7,9-trans-11,14-cis-eicosatetraenoic acid (5S,6S-DHETE). The kinetic parameters for the formation of 5S,6S-DHETE and leukotriene B4 were found to be similar. Also, both activities were susceptible to suicide inactivation and were equally sensitive to inhibition by bestatin. Moreover, from the stereochemical configuration of the vicinal diol, it could be inferred that 5S, 6S-DHETE is formed via an SN1 mechanism involving a carbocation intermediate, which in turn indicates that enzymatic hydrolysis of leukotriene A4 into leukotriene B4 follows the same mechanism. Inasmuch as soluble epoxide hydrolase utilizes leukotriene A4 as substrate to produce 5S,6R-DHETE, our results also suggest a functional relationship between leukotriene A4 hydrolase and xenobiotic epoxide hydrolases.
Collapse
Affiliation(s)
- M B Andberg
- Department of Medical Biochemistry and Biophysics, Division of Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | | | | |
Collapse
|
14
|
Borhan B, Jones AD, Pinot F, Grant DF, Kurth MJ, Hammock BD. Mechanism of soluble epoxide hydrolase. Formation of an alpha-hydroxy ester-enzyme intermediate through Asp-333. J Biol Chem 1995; 270:26923-30. [PMID: 7592938 DOI: 10.1074/jbc.270.45.26923] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
18O-Labeled epoxides of trans-1,3-diphenylpropene oxide (tDPPO) and cis-9,10-epoxystearic acid were synthesized and used to determine the regioselectivity of sEH. The nucleophilic nature of sEH catalysis was demonstrated by comparing the enzymatic and nonenzymatic hydrolysis products of tDPPO. The results from single turnover experiments with greater or equal molar equivalents of sEH:substrate were consistent with the existence of a stable intermediate formed by a nucleophilic amino acid attacking the epoxide group. Tryptic digestion of sEH previously subjected to multiple turnovers with tDPPO in H2 18O resulted in the isolation and purification of a tryptic fragment containing Asp-333. Electrospray mass spectrometry of this fragment conclusively illustrated the incorporation of 180. After complete digestion of the latter peptide it was shown that Asp-333 of sEH exhibited an increased mass. The attack by Asp-333 initiates enzymatic activity, leading to the formation of an alpha-hydroxyacyl-enzyme intermediate. Hydrolysis of the acyl-enzyme occurs by the addition of an activated water to the carbonyl carbon of the ester bond, after which the resultant tetrahedral intermediate collapses, yielding the active enzyme and the diol product.
Collapse
Affiliation(s)
- B Borhan
- Department of Chemistry, University of California, Davis 95616, USA
| | | | | | | | | | | |
Collapse
|
15
|
Pinot F, Grant DF, Spearow JL, Parker AG, Hammock BD. Differential regulation of soluble epoxide hydrolase by clofibrate and sexual hormones in the liver and kidneys of mice. Biochem Pharmacol 1995; 50:501-8. [PMID: 7646556 DOI: 10.1016/0006-2952(95)00167-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Soluble epoxide hydrolase (sEH) activity was measured in the liver and kidneys of male, female, and castrated male mice in order to evaluate sex- and tissue-specific differences in enzyme expression. sEH activity was found to be higher in liver than in kidneys. Activity increased with age in the liver of females, males and castrated males, but only in males did activity in the kidneys increase. There was greater activity in both the liver and kidneys of adult males than females. This sexual dimorphism was more pronounced in the kidneys (283% higher) than in the liver (55% higher). Castration of males led to a decrease in activity in both organs, but it had a greater effect on renal activity (67% decrease) than on hepatic activity (27% decrease). Treatment of castrated mice with testosterone led to an increase in sEH activity of 400% in kidneys and 49% in liver compared with surgical controls. These results suggest differential regulation of sEH by testosterone in kidneys and liver. Ovariectomized female mice had renal and hepatic activities approximately 30% greater than control females. Feeding mice with the hypolipidemic drug clofibrate produced stronger induction of sEH in liver than in kidneys. Testosterone treatment, however, caused greater induction in kidneys than in liver of females and castrated males and had no effect in either kidneys or liver in males. When given together, the effects of these two compounds appeared to be additive in both liver and kidneys. Results from western blot showed that the increase in sEH enzyme activity in kidneys is correlated with an increase in sEH protein. These results suggest that clofibrate and testosterone independently regulate sEH activity in vivo, and that kidneys and liver respond differently to clofibrate and testosterone.
Collapse
Affiliation(s)
- F Pinot
- Department of Entomology, University of California, Davis 95616-8584, USA
| | | | | | | | | |
Collapse
|
16
|
Pinot F, Grant DF, Beetham JK, Parker AG, Borhan B, Landt S, Jones AD, Hammock BD. Molecular and biochemical evidence for the involvement of the Asp-333-His-523 pair in the catalytic mechanism of soluble epoxide hydrolase. J Biol Chem 1995; 270:7968-74. [PMID: 7713895 DOI: 10.1074/jbc.270.14.7968] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In order to investigate the involvement of amino acids in the catalytic mechanism of the soluble epoxide hydrolase, different mutants of the murine enzyme were produced using the baculovirus expression system. Our results are consistent with the involvement of Asp-333 and His-523 in a catalytic mechanism similar to that of other alpha/beta hydrolase fold enzymes. Mutation of His-263 to asparagine led to the loss of approximately half the specific activity compared to wild-type enzyme. When His-332 was replaced by asparagine, 96.7% of the specific activity was lost and mutation of the conserved His-523 to glutamine led to a more dramatic loss of 99.9% of the specific activity. No activity was detectable after the replacement of Asp-333 by serine. However, more than 20% of the wild-type activity was retained in an Asp-333-->Asn mutant produced in Spodoptera frugiperda cells. We purified, by affinity chromatography, the wild-type and the Asp-333-->Asn mutant enzymes produced in Trichoplusia ni cells. We labeled these enzymes by incubating them with the epoxide containing radiolabeled substrate juvenile hormone III (JH III). The purified Asp-333-->Asn mutant bound 6% of the substrate compared to the wild-type soluble epoxide hydrolase. The mutant also showed 8% of the specific activity of the wild-type. Preincubation of the purified Asp-333-->Asn mutant at 37 degrees C (pH 8), however, led to a complete recovery of activity and to a change of isoelectric point (pI), both of which are consistent with hydrolysis of Asn-333 to aspartic acid. This intramolecular hydrolysis of asparagine to aspartic acid may explain the activity observed in this mutant. Wild-type enzyme that had been radiolabeled with the substrate was digested with trypsin. Using reverse phase-high pressure liquid chromatography, we isolated four radiolabeled peptides of similar polarity. These peptides were not radiolabeled if the enzyme was preincubated with a selective competitive inhibitor of soluble epoxide hydrolase 4-fluorochalcone oxide. This strongly suggested that these peptides contained a catalytic amino acid. Each peptide was characterized with N-terminal amino acid sequencing and electrospray mass spectrometry. All four radiolabeled peptides contained overlapping sequences. The only aspartic acid present in all four peptides and conserved in all epoxide hydrolases was Asp-333. These peptides resulted from cleavage at different trypsin sites and the mass of each was consistent with the covalent linkage of Asp-333 to the substrate.
Collapse
Affiliation(s)
- F Pinot
- Department of Entomology, University of California, Davis 95616-8584, USA
| | | | | | | | | | | | | | | |
Collapse
|
17
|
|
18
|
Arand M, Grant DF, Beetham JK, Friedberg T, Oesch F, Hammock BD. Sequence similarity of mammalian epoxide hydrolases to the bacterial haloalkane dehalogenase and other related proteins. Implication for the potential catalytic mechanism of enzymatic epoxide hydrolysis. FEBS Lett 1994; 338:251-6. [PMID: 8307189 DOI: 10.1016/0014-5793(94)80278-5] [Citation(s) in RCA: 129] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Direct comparison of the amino acid sequences of microsomal and soluble epoxide hydrolase superficially indicates that these enzymes are unrelated. Both proteins, however, share significant sequence similarity to a bacterial haloalkane dehalogenase that has earlier been shown to belong to the alpha/beta hydrolase fold family of enzymes. The catalytic mechanism for the dehalogenase has been elucidated in detail [Verschueren et al. (1993) Nature 363, 693-698] and proceeds via an ester intermediate where the substrate is covalently bound to the enzyme. From these observations we conclude (i) that microsomal and soluble epoxide hydrolase are distantly related enzymes that have evolved from a common ancestral protein together with the haloalkane dehalogenase and a variety of other proteins specified in the present paper, (ii) that these enzymes most likely belong to the alpha/beta hydrolase fold family of enzymes and (iii) that the enzymatic epoxide hydrolysis proceeds via a hydroxy ester intermediate, in contrast to the presently favoured base-catalyzed direct attack of the epoxide by an activated water.
Collapse
Affiliation(s)
- M Arand
- Institute of Toxicology, University of Mainz, Germany
| | | | | | | | | | | |
Collapse
|
19
|
Nourooz-Zadeh J, Uematsu T, Borhan B, Kurth MJ, Hammock BD. Characterization of the cytosolic epoxide hydrolase-catalyzed hydration products from 9,10:12,13-diepoxy stearic esters. Arch Biochem Biophys 1992; 294:675-85. [PMID: 1567223 DOI: 10.1016/0003-9861(92)90741-e] [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: 12/27/2022]
Abstract
In a previous report we hypothesized that diepoxy fatty methylesters are metabolized to tetraols and/or tetrahydrofurandiols through an epoxydiol intermediate. In this study, p-nitrophenyldiepoxystearate was incubated with affinity-purified liver cytosolic epoxide hydrolase and product formation was monitored by reverse phase HPLC. The diepoxystearate was converted to the corresponding 9,10,12,13-tetraol using a concentrated enzyme (greater than or equal to 100 micrograms/ml). When lower concentration of the enzyme was used, simultaneous elevation of 9,10-epoxy-12,13-dihydroxy and 12,13-epoxy-9,10-dihydroxystearate along with disappearance of tetraol was observed. The epoxydiols were intermediates which could be isolated and cyclized quantitatively to form two chromatographically distinct tetrahydrofurandiols (A with a low Rf value and B with a high Rf value on TLC). Gas chromatographic analysis on a cyclodex-beta capillary column revealed that each compound was composed of two different isomers. The structure of these isomers was 9(12)-oxy-10,13-dihydroxystearate and 10(13)-oxy-9,12-dihydroxystearate using mass spectrometry. Stereochemistry of the aliphatic chain across the tetrahydrofuran moiety was determined by nuclear Overhauser effect spectroscopy. Chemically and enzymatically generated tetrahydrofurandiols had similar retention time on GC and HPLC, and identical mass spectra using the electron impact mode.
Collapse
Affiliation(s)
- J Nourooz-Zadeh
- Department of Entomology, University of California, Davis 95616
| | | | | | | | | |
Collapse
|