Novel membrane-associated prostaglandin E synthase-2 from crustacean arthropods

Hansen, Kristella; Varvas, Külliki; Järving, Ivar; Samel, Nigulas

doi:10.1016/j.cbpb.2014.05.004

Cited by 13 publications

(9 citation statements)

References 39 publications

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“…Prostaglandin (PG) E1 and E2 (PGE1 and PGE2, respectively) are synthesized through the cyclooxygenase (COX) pathway by coupling reactions of COX-1 or COX-2 and PGE1/E2 synthases (PGES) using 20-carbon ω−6 fatty acids of dihomo-γ-linolenic acid (DGLA) and arachidonic acid (AA) as substrates, respectively [1][2][3][4] . Three PGES, noninducible types of cytosolic PGES (cPGES) 5,6 and microsomal PGES-2 (mPGES-2) 6,7 , and an inducible type of microsomal PGES-1 (mPGES-1) 5,6,8,9 have been cloned and characterized previously. PGE2 synthesized by the inducible mPGES-1 is one of the major mediators for inflammatory diseases, such as arthritis 10,11 , vascular inflammation 12,13 , angiogenesis and some types of cancers [14][15][16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

The key residue within the second extracellular loop of human EP3 involved in selectively turning down PGE2- and retaining PGE1-mediated signaling in live cells

Akasaka

Thaliachery

Zheng

et al. 2017

Archives of Biochemistry and Biophysics

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Key residues and binding mechanisms of PGE and PGE on prostanoid receptors are poorly understood due to the lack of X-ray structures for the receptors. We constructed a human EP3 (hEP3) model through integrative homology modeling using the X-ray structure of the β-adrenergic receptor transmembrane domain and NMR structures of the thromboxane A2 receptor extracellular loops. PGE and PGE docking into the hEP3 model showed differing configurations within the extracellular ligand recognition site. While PGE could form possible binding contact with S211, PGE is unable to form similar contacts. Therefore, S211 could be the critical residue for PGE recognition, but is not a significant for PGE. This prediction was confirmed using HEK293 cells transfected with hEP3 S211L cDNA. The S211L cells lost PGE binding and signaling. Interestingly, the S211L cells retained PGE-mediated signaling. It indicates that S211 within the second extracellular loop is a key residue involved in turning down PGE signaling. Our study provided information that S211L within EP3 is the key residue to distinguish PGE and PGE binding to mediate diverse biological functions at the initial recognition step. The S211L mutant could be used as a model for studying the binding mechanism and signaling pathway specifically mediated by PGE.

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Section: Introductionmentioning

confidence: 99%

The key residue within the second extracellular loop of human EP3 involved in selectively turning down PGE2- and retaining PGE1-mediated signaling in live cells

Akasaka

Thaliachery

Zheng

et al. 2017

Archives of Biochemistry and Biophysics

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“…Three PGE 2 synthases, microsomal prostaglandin E2 (PGE 2 ) synthase (mPGES)-1, mPGES-2 and cytosolic PGE 2 synthase (cPGES), have been cloned [1][2][3][4] . mPGES-1 is the major enzyme involved in producing inflammatory PGE 2 through instantly accepting the inducible cyclooxygenase (COX)-2-produced PGH 2 as a substrate.…”

Section: Introductionmentioning

confidence: 99%

Identification of the two-phase mechanism of arachidonic acid regulating inflammatory prostaglandin E2 biosynthesis by targeting COX-2 and mPGES-1

Akasaka

Ruan

2016

Archives of Biochemistry and Biophysics

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Through linking inducible cyclooxygenase (COX)-2 with microsomal prostaglandin E2 (PGE2) synthase-1 (mPGES-1), a Single-Chain Enzyme Complex (SCEC, COX-2-10aa-mPGES-1) was engineered to mimic a specific inflammatory PGE2 biosynthesis from omega-6 fatty acid, arachidonic acid (AA), by eliminating involvements of non-inducible COX-1 and other PGE2 synthases. Using the SCEC, we characterized coupling reactions between COX-2 and mPGES-1 at 1:1 ratio of inflammatory PGE2 production. AA demonstrated two phase activities to regulate inflammatory PGE2 production. In the first phase (<2 μM), AA was a COX-2 substrate and converted to increasing production of PGE2. In the second phase with a further increased AA level (2-10 μM), AA bound to mPGES-1 and inhibited the PGE2 production. The SCEC study was identical to the co-expression of COX-2 and mPGES-1. This was further confirmed by using mPGES-1 and PGH2 as a direct enzyme target and substrate, respectively. Furthermore, the carboxylic acid group of AA binding to R67 and R70 of mPGES-1 was identified by X-ray structure-based docking and mutagenesis. mPGES-1 mutants, R70A, R70K, R67A and R67K, lost 40-100% binding to [(14)C]-AA. To conclude, a cellular model, in which AA is involved in self-controlling initial initiating and later resolving inflammation by its two phase activities, was discussed.

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“…More than 30 mPGES2-like sequences have been identified in insects and other arthropod genomes ( Hansen et al, 2014 ). Two mPGES2 proteins purified from amphipod crustaceans, Gammarus sp.…”

Section: Discussionmentioning

confidence: 99%

“…However, phylogenetic analysis indicates that the arthropod mPGES2 sequences are distinctively clustered, separate from vertebrate orthologs ( Eichner et al, 2015 ). Unlike vertebrate mPGES2s, the arthropod type exhibits a very low heme-binding affinity ( Hansen et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

“…Third, the synthesized PGH 2 is likely to be isomerized into PGE 2 by mPGES2 because other cellular PGES or mPGES1 are not identified in insect genomes. Two amphipod mPGES2s produce PGE 2 from PGH 2 ( Hansen et al, 2014 ), from which we posed the hypothesis that Se-mPGES2 catalyzes biosynthesis of physiologically active PGE 2 through its cognate protein. Here, we report on the outcomes of experiments designed to test our hypothesis.…”

Section: Introductionmentioning

confidence: 99%

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An Insect Prostaglandin E2 Synthase Acts in Immunity and Reproduction

2018

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Eicosanoids, oxygenated metabolites of C20 polyunsaturated fatty acids (PUFAs), mediate fundamental physiological processes, including immune reactions and reproduction, in insects. Prostaglandins (PGs) make up one group of eicosanoids, of which PGE2 is a relatively well-known mediator in various insect taxa. While PG biosynthesis has been reported, the specific biosynthetic pathway for PGE2 is not known in insects. Here, we posed the hypothesis that Se-mPGES2 mediates biosynthesis of physiologically active PGE2 through its cognate protein. To test this hypothesis, we interrogated a transcriptome of the lepidopteran insect, Spodoptera exigua, to identify a candidate PGE2 synthase (Se-mPGES2) and analyzed its sequence and expression. Its predicted amino acid sequence contains a consensus thioredoxin homology sequence (Cys-x-x-Cys) responsible for catalytic activity along with an N-terminal membrane-associated hydrophobic domain and C-terminal cytosolic domain. It also shares sequence homology (36.5%) and shares almost overlapping three dimensional structures with a membrane-bound human PGES2 (mPGES2). Se-mPGES2 was expressed in all developmental stages with high peaks during the late larval instar and adult stages. Immune challenge significantly up-regulated its expression levels in hemocytes and fat body. Injecting double-stranded RNA (dsRNA) specific to Se-mPGES2 significantly impaired two cellular immune responses, hemocyte-spreading behavior and nodule formation following bacterial challenge. Humoral immunity was also significantly suppressed, registered as reduced phenoloxidase activity and antimicrobial peptide expression levels. The suppressed immune responses were reversed following PGE2, but not arachidonic acid (AA), treatments. RNAi treatments also reduced the egg-laying behavior of females. Control females mated with the RNAi-treated males led to substantially reduced egg-laying behavior, which was also reversed following PGE2 injections into females. These results strongly bolster our hypothesis that Se-mPGES2 acts in the biosynthesis of PGE2, a crucial biochemical signal mediating immune and reproductive physiology of S. exigua.

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Novel membrane-associated prostaglandin E synthase-2 from crustacean arthropods

Cited by 13 publications

References 39 publications

The key residue within the second extracellular loop of human EP3 involved in selectively turning down PGE2- and retaining PGE1-mediated signaling in live cells

The key residue within the second extracellular loop of human EP3 involved in selectively turning down PGE2- and retaining PGE1-mediated signaling in live cells

Identification of the two-phase mechanism of arachidonic acid regulating inflammatory prostaglandin E2 biosynthesis by targeting COX-2 and mPGES-1

An Insect Prostaglandin E2 Synthase Acts in Immunity and Reproduction

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