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Yoshihiro Urade

Publications and source records attributed to Yoshihiro Urade.

At least 19 recordsLinked to original sources
PubMed2003

Prostaglandin E2 activates the histaminergic system via the EP4 receptor to induce wakefulness in rats.

Prostaglandin (PG)E2 promotes the wakeful state when administered into the posterior hypothalamus, in which the histaminergic tuberomammillary nucleus (TMN) is located. To explore the neurotransmitter mechanisms responsible for PGE2-induced wakefulness in rats, we examined the effect of PGE2 on the activity of the histaminergic system and the involvement of PGE2 receptor subtypes in the response. PGE2 perfusion in the TMN at doses of 100, 200, and 400 pmol/min for 2 hr significantly increased histamine release from the medial preoptic area and frontal cortex in a dose-dependent manner, as measured by in vivo microdialysis. Among the agonists of the four distinct subtypes of PGE2 receptors (EP1-4) tested, only the EP4 receptor agonist (ONO-AE1-329) mimicked the excitatory effect of PGE2 on histamine release from both the medial preoptic area and frontal cortex. Perfusion of either PGE2 or the EP4 agonist into the TMN at a dose of 200 pmol/min for 1 hr increased histidine decarboxylase activity, histidine decarboxylase mRNA level, and histamine content in the hypothalamus. In situ hybridization revealed that EP4 receptor mRNA was expressed in histidine decarboxylase-immunoreactive neurons of the TMN region. Furthermore, EP4 agonist perfusion into the TMN induced wakefulness. These findings indicate that PGE2 induces wakefulness through activation of the histaminergic system via EP4 receptors.

Animals↗
PubMed2003

Specific regulation of lipocalin-type prostaglandin D synthase in mouse heart by estrogen receptor beta.

Estrogens have important physiological roles in the cardiovascular system. We use DNA microarray technology to study the molecular mechanism of estrogen action in the heart and to identify novel estrogen-regulated genes. In this investigation we identify genes that are regulated by chronic estrogen treatment of mouse heart. We present our detailed characterization of one of these genes, lipocalin-type prostaglandin D synthase (L-PGDS). Northern and Western blot analysis revealed that L-PGDS was induced both by acute and chronic estrogen treatment. Northern blot analysis, using estrogen receptor (ER)-disrupted mice, suggests that L-PGDS is specifically induced by ERbeta in vivo. In further support of ERbeta-selective regulation, we identify a functional estrogen-responsive element in the L-PGDS promoter, the activity of which is up-regulated by ERbeta, but not by ERalpha. We demonstrate that a one-nucleotide change (A to C) in the L-PGDS estrogen-responsive element affects receptor selectivity.

Animals↗
PubMed2003

Effect of phospholipase Cbeta4 lacking in thalamic neurons on electroencephalogram.

Activity of thalamic neurons has been shown to be modulated via type-1 metabotropic glutamate receptor (mGluR1) activation, which initiates an intracellular Ca signaling cascade involving phospholipase Cbeta4 (PLCbeta4) and leading to the activation of conventional protein kinase C (cPKC). In the present study, we investigated the role of PLCbeta4 in thalamic neuron. PLCbeta4-deficient mutant mice were found to exhibit three phenotypic characteristics: (1) a 2-Hz increase in the peak frequency of electroencephalogram (EEG) of rapid eye movement (REM) sleep, (2) an increase in the frequency of miniature excitatory postsynaptic currents (mEPSCs) recorded in thalamus, and (3) waveform distortion of EEG. We postulate here that changes in protein phosphorylation due to reduced cPKC activity by PLCbeta4 deletion in thalamic neurons may give rise to these phenotypic characteristics. Taken together, these results indicate that reduced PLCbeta4 activity in thalamic neurons may underlie high-cortical oscillation frequency.

Animals↗
PubMed2003

Hematopoietic prostaglandin D synthase is expressed in microglia in the developing postnatal mouse brain.

Hematopoietic prostaglandin D synthase (HPGDS) is a PGD(2)-synthesizing enzyme and is expressed in antigen-presenting cells, mast cells, and other immunocompetent cells. We here report the HPGDS expression in microglia and the migration pathway of microglia in the developing mouse brain as detected by HPGDS immunohistochemistry. Expression of HPGDS mRNA peaked at postnatal day (PND) 10, decreased gradually thereafter, and reached a plateau at PND 20. The mRNAs for target molecules of PGD(2), i.e., DP receptor (DPR) and CRTH2 receptor, showed developmental profiles overlapped to that of HPGDS. Most of the HPGDS(+) cells at PND 10 had morphological characteristics of ameboid microglia and gave positive immunostaining with microglia-specific markers such as RCA-1, F4/80, or ER-MP12. These specific markers became less detectable later on, but HPGDS was still expressed even in resting microglia. Thus, HPGDS is a useful marker for investigation of microglial development. Spaciotemporal evaluation of microglial development and migration with HPGDS immunostaining revealed the following three major possible migration pathways of microglia in the postnatal brain: from the lateral ventricle via subventricular zones to brain parenchyma; from the leptomeninges around the cerebellopontine angle to the cerebellar white matter; and from the overlying leptomeninges to the hippocampus, basal forebrain, and brainstem.

Aging↗
PubMed2003

Prostaglandin production from arachidonic acid and evidence for a 9,11-endoperoxide prostaglandin H2 reductase in Leishmania.

Lysates of Leishmania promastigotes can metabolise arachidonic acid to prostaglandins. Prostaglandin production was heat sensitive and not inhibited by aspirin or indomethacin. We cloned and sequenced the cDNA of Leishmania major, Leishmania donovani, and Leishmania tropica prostaglandin F(2alpha) synthase, and overexpressed their respective 34-kDa recombinant proteins that catalyse the reduction of 9,11-endoperoxide PGH(2) to PGF(2alpha). Database search and sequence alignment showed that L. major prostaglandin F(2alpha) synthase exhibits 61, 99.3, and 99.3% identity with Trypanosoma brucei, L. donovani, and L. tropica prostaglandin F(2alpha) synthase, respectively. Using polymerase chain reaction amplification, Western blotting, and immunofluorescence, we have demonstrated that prostaglandin F(2alpha) synthase protein and gene are present in Old World and absent in New World Leishmania, and that this protein is localised to the promastigote cytosol.

Animals↗
PubMed2003

Mechanism of metal activation of human hematopoietic prostaglandin D synthase.

Here we report the crystal structures of human hematopoietic prostaglandin (PG) D synthase bound to glutathione (GSH) and Ca2+ or Mg2+. Using GSH as a cofactor, prostaglandin D synthase catalyzes the isomerization of PGH2 to PGD2, a mediator for allergy response. The enzyme is a homodimer, and Ca2+ or Mg2+ increases its activity to approximately 150% of the basal level, with half maximum effective concentrations of 400 microM for Ca2+ and 50 microM for Mg2+. In the Mg2+-bound form, the ion is octahedrally coordinated by six water molecules at the dimer interface. The water molecules are surrounded by pairs of Asp93, Asp96 and Asp97 from each subunit. Ca(2+) is coordinated by five water molecules and an Asp96 from one subunit. The Asp96 residue in the Ca2+-bound form makes hydrogen bonds with two guanidium nitrogen atoms of Arg14 in the GSH-binding pocket. Mg2+ alters the coordinating water structure and reduces one hydrogen bond between Asp96 and Arg14, thereby changing the interaction between Arg14 and GSH. This effect explains a four-fold reduction in the K(m) of the enzyme for GSH. The structure provides insights into how Ca2+ or Mg2+ binding activates human hematopoietic PGD synthase.

Amino Acid Sequence↗
PubMed2003

Cloning, expression, crystallization, and preliminary X-ray analysis of recombinant mouse lipocalin-type prostaglandin D synthase, a somnogen-producing enzyme.

Lipocalin-type prostaglandin D synthase is the key enzyme for the production of prostaglandin D(2), a potent endogenous somnogen, in the brain. We cloned, produced, and crystallized the native enzyme and selenomethionyl Cys(65)Ala mutants of the recombinant mouse protein by the hanging drop vapor-diffusion method with both malonate and citrate as precipitants. The native crystals obtained with malonate belong to orthorhombic space group P2(1)2(1)2(1) with lattice constants a = 46.2, b = 66.8, and c = 105.3 A. The selenomethionyl crystals obtained with citrate belong to orthorhombic space group C222(1) with lattice constants a = 45.5, b = 66.8, and c = 104.5 A. The native crystals diffracted beyond 2.1 A resolution.

Animals↗
PubMed2002

Prostaglandin production from arachidonic acid and evidence for a 9,11-endoperoxide prostaglandin H2 reductase in Leishmania.

Lysates of Leishmania promastigotes can metabolise arachidonic acid to prostaglandins. Prostaglandin production was heat sensitive and not inhibited by aspirin or indomethacin. We cloned and sequenced the cDNA of Leishmania major, Leishmania donovani, and Leishmania tropica prostaglandin F(2alpha) synthase, and overexpressed their respective 34-kDa recombinant proteins that catalyse the reduction of 9,11-endoperoxide PGH(2) to PGF(2alpha). Database search and sequence alignment alignment showed that L. major prostaglandin F(2alpha) synthase exhibits 61, 99.3, and 99.3% identity with Trypanosoma brucei, L. donovani, and L. tropica prostaglandin F(2alpha) synthase, respectively. Using polymerase chain reaction amplification, Western blotting, and immunofluorescence, we have demonstrated that prostaglandin F(2alpha) synthase protein and gene are present in Old World and absent in New World Leishmania, and that this protein is localised to the promastigote cytosol.

Animals↗
PubMed2002

Regulation of lipocalin-type prostaglandin D synthase gene expression by Hes-1 through E-box and interleukin-1 beta via two NF-kappa B elements in rat leptomeningeal cells.

The promoter function of the rat lipocalin-type prostaglandin D synthase (L-PGDS) gene was characterized in primary cultures of leptomeningeal cells prepared from the neonatal rat brain. Luciferase reporter assays with deletion and site-directed mutation of the promoter region (-1250 to +77) showed that an AP-2 element at -109 was required for activation and an E-box at +57, for repression. Binding of nuclear factors to each of these cis-elements was demonstrated by an electrophoretic mobility shift assay. Several components of the Notch-Hes signaling pathway, Jagged, Notch1, Notch3, and Hes-1, were expressed in the leptomeningeal cells. Human Hes-1 co-expressed in the leptomeningeal cells bound to the E-box of the rat L-PGDS gene, and repressed the promoter activity of the rat L-PGDS gene in a dose-dependent manner. The L-PGDS gene expression was up-regulated slowly by interleukin-1 beta to the maximum level at 24 h. The reporter assay with deletion and mutation revealed that two NF-kappa B elements at -1106 and -291 were essential for this up-regulation. Binding of two NF-kappa B subunits, p65 and c-Rel, to these two NF-kappa B elements occurred after the interleukin-1 beta treatment. Therefore, the L-PGDS gene is the first gene identified as the target for the Notch-Hes signal through the E-box among a variety of genes involved in the prostanoid biosynthesis, classified to the lipocalin family, and expressed in the leptomeninges. Moreover, the L-PGDS gene is a unique gene that is activated slowly by the NF-kappa B system.

Animals↗
PubMed2002

Characterization of the unfolding process of lipocalin-type prostaglandin D synthase.

We found that low concentrations of guanidine hydrochloride (GdnHCl, <0.75 M) or urea (<1.5 M) enhanced the enzyme activity of lipocalin-type prostaglandin (PG) D synthase (L-PGDS) maximally 2.5- and 1.6-fold at 0.5 M GdnHCl and 1 M urea, respectively. The catalytic constants in the absence of denaturant and in the presence of 0.5 M GdnHCl or 1 m urea were 22, 57, and 30 min(-1), respectively, and the K(m) values for the substrate, PGH(2), were 2.8, 8.3, and 2.3 microm, respectively, suggesting that the increase in the catalytic constant was mainly responsible for the activation of L-PGDS. The intensity of the circular dichroism (CD) spectrum at 218 nm, reflecting the beta-sheet content, was also increased by either denaturant in a concentration-dependent manner, with the maximum at 0.5 M GdnHCl or 1 M urea. By plotting the enzyme activities against the ellipticities at 218 nm of the CD spectra of L-PGDS in the presence or absence of GdnHCl or urea, we found two states in the reversible folding process of L-PGDS: one is an activity-enhanced state and the other, an inactive state. The NMR analysis of L-PGDS revealed that the hydrogen-bond network was reorganized to be increased in the activity-enhanced state formed in the presence of 0.5 M GdnHCl or 1 m urea and to be decreased but still remain in the inactive intermediate observed in the presence of 2 M GdnHCl or 4 M urea. Furthermore, binding of the nonsubstrate ligands, bilirubin or 13-cis-retinal, to L-PGDS changed from a multistate mode in the native form of L-PGDS to a simple two-state mode in the activity-enhanced form, as monitored by CD spectra of the bound ligands. Therefore, L-PGDS is a unique protein whose enzyme activity and ligand-binding property are biphasically altered during the unfolding process by denaturants.

Animals↗
PubMed2002

A key role for old yellow enzyme in the metabolism of drugs by Trypanosoma cruzi.

Trypanosoma cruzi is the etiological agent of Chagas' disease. So far, first choice anti-chagasic drugs in use have been shown to have undesirable side effects in addition to the emergence of parasite resistance and the lack of prospect for vaccine against T. cruzi infection. Thus, the isolation and characterization of molecules essential in parasite metabolism of the anti-chagasic drugs are fundamental for the development of new strategies for rational drug design and/or the improvement of the current chemotherapy. While searching for a prostaglandin (PG) F(2alpha) synthase homologue, we have identified a novel "old yellow enzyme" from T. cruzi (TcOYE), cloned its cDNA, and overexpressed the recombinant enzyme. Here, we show that TcOYE reduced 9,11-endoperoxide PGH(2) to PGF(2alpha) as well as a variety of trypanocidal drugs. By electron spin resonance experiments, we found that TcOYE specifically catalyzed one-electron reduction of menadione and beta-lapachone to semiquinone-free radicals with concomitant generation of superoxide radical anions, while catalyzing solely the two-electron reduction of nifurtimox and 4-nitroquinoline-N-oxide drugs without free radical production. Interestingly, immunoprecipitation experiments revealed that anti-TcOYE polyclonal antibody abolished major reductase activities of the lysates toward these drugs, identifying TcOYE as a key drug-metabolizing enzyme by which quinone drugs have their mechanism of action.

Amino Acid Sequence↗
PubMed2002

Perineuronal oligodendrocytes protect against neuronal apoptosis through the production of lipocalin-type prostaglandin D synthase in a genetic demyelinating model.

The genetic demyelinating mouse "twitcher" is a model of the human globoid cell leukodystrophy, caused by galactosylceramidase (GALC) deficiency. Demyelination in the twitcher brain is secondary to apoptotic death of oligodendrocytes (OLs). Lipocalin-type prostaglandin (PG) D synthase (L-PGDS), a protein expressed in mature OLs, was progressively upregulated in twitcher OLs; whereas expression of OL-associated proteins such as carbonic anhydrase II, myelin basic protein, and myelin-associated glycoprotein was downregulated during demyelination in twitcher brains. The upregulation of L-PGDS was more remarkable in perineuronal OLs than in interfascicular OLs. A larger number of L-PGDS-positive OLs was found in selected fiber tracts of twitcher brains where fewer apoptotic cells were detected. The distribution of L-PGDS-positive OLs was inversely related to the severity of demyelination, as assessed by accumulation of scavenger macrophages. Mice doubly deficient for L-PGDS and GALC disclosed a large number of apoptotic neurons, which were never seen in twitcher brains, in addition to an increased number of apoptotic OLs. A linear positive correlation was observed between the population of L-PGDS-positive OLs in the twitcher brain and the ratio of apoptotic nuclei in the double mutant versus those in the twitcher, suggesting a dose-dependent effect of L-PGDS against apoptosis. These lines of evidence suggest that L-PGDS is an anti-apoptotic molecule protecting neurons and OLs from apoptosis in the twitcher mouse. This is a novel example of OL-neuronal interaction.

Animals↗
PubMed2002

Induction of hematopoietic prostaglandin D synthase in hyalinated necrotic muscle fibers: its implication in grouped necrosis.

Prostaglandin (PG) D(2) exerts pro-inflammatory and anti-inflammatory functions under various pathological conditions. We found that the immunoreactivity of hematopoietic PGD synthase (HPGDS) appeared in necrotic muscle fibers, mainly in foci of grouped necrosis, in Duchenne's muscular dystrophy (DMD) and polymyositis (PM), but not in Becker's muscular dystrophy or in Fukuyama-type congenital muscular dystrophy. The HPGDS expression in DMD and PM was observed to be transient in hyalinated fibers at the early necrotic stage but not detected in opaque fibers, in fibers infiltrated by monocytes/lymphocyte, or in regenerating fibers. The immunoreactivities of a cytosolic form of phospholipase A(2) and cyclooxygenase-2, the upstream enzymes of the arachnoid acid cascade, were similarly observed in the HPGDS-positive fibers, suggesting that PGD(2) was produced in situ in those necrotic muscle fibers.

Adolescent↗
PubMed2002

Regulation of prostaglandin endoperoxide synthase-2 and IL-6 expression in mouse bone marrow-derived mast cells by exogenous but not endogenous prostanoids.

Mouse bone marrow-derived mast cells (BMMC), stimulated with stem cell factor, IL-1beta, and IL-10, secrete IL-6 and demonstrate a delayed phase of PGD(2) generation that is dependent upon the induced expression of PG endoperoxide synthase (PGHS)-2. We have examined the potential for exogenous prostanoids, acting in a paracrine fashion, and endogenous prostanoids, acting in an autocrine fashion, to regulate PGHS-2 induction and IL-6 secretion in mouse BMMC. Exogenous PGE(2), which acts through G protein-coupled receptors, and 15-deoxy-Delta(12,14)-PGJ(2), which is a ligand for peroxisome proliferator-activated receptor (PPAR)gamma, elicited a 2- to 3-fold amplification of PGHS-2 induction, delayed-phase PGD(2) generation, and IL-6 secretion in response to stem cell factor, IL-1beta, and IL-10. The effect of PGE(2) was reproduced by the E prostanoid (EP)1 receptor agonist 17-trinor-PGE(2), and the EP1/EP3 agonist, sulprostone, but not the EP2 receptor agonist, butaprost. Although BMMC express PPARgamma, the effects of 15-deoxy-Delta(12,14)-PGJ(2) were not reproduced by the PPARgamma agonists, troglitazone and ciglitazone. PGHS-2 induction, but not IL-6 secretion, was impaired in cPLA(2)-deficient BMMC. However, there was no impairment of PGHS-2 induction in BMMC deficient in hematopoietic PGD synthase or PGHS-1 in the presence or absence of the PGHS-2 inhibitor, NS-398. Thus, although exogenous prostanoids may contribute to amplification of the inflammatory response by augmenting PGD(2) generation and IL-6 secretion from mast cells, endogenous prostanoids do not play a role.

Adjuvants, Immunologic↗
PubMed2002

Biochemical characterization of mouse microsomal prostaglandin E synthase-1 and its colocalization with cyclooxygenase-2 in peritoneal macrophages.

We cloned the cDNA for mouse microsomal prostaglandin (PG) E synthase-1 (mPGES-1) and expressed the recombinant enzyme in Escherichia coli. The membrane fraction containing recombinant mPGES-1 catalyzed the isomerization of PGH2 to PGE2 in the presence of GSH with K(m) values of 130 microM for PGH2 and 37 microM for GSH, a turnover number of 600 min(-1), and a k(cat)/K(m) ratio of 4.6 min(-1) microM(-1). Recombinant mPGES-1 was purified and used to generate a polyclonal antibody highly specific for mPGES-1. The antibody showed a single band on Western blotting of microsomal fractions from lipopolysaccharide-treated mouse peritoneal macrophages. Northern and Western blotting analyses revealed that mPGES-1 was induced together with cyclooxygenase-2 in mouse macrophages after treatment of the cells with lipopolysaccharide. Confocal immunofluorescence microscopy revealed that both mPGES-1 and cyclooxygenase-2 were colocalized in the lipopolysaccharide-treated macrophages. Taken together, these results demonstrate that mPGES-1 is an efficient downstream enzyme for the production of PGE2 in the activated macrophages treated by lipopolysaccharide.

Animals↗
PubMed2002

Pronounced eosinophilic lung inflammation and Th2 cytokine release in human lipocalin-type prostaglandin D synthase transgenic mice.

PGD(2) is a major lipid mediator released from mast cells, but little is known about its role in the development of allergic reactions. We used transgenic (TG) mice overexpressing human lipocalin-type PGD synthase to examine the effect of overproduction of PGD(2) in an OVA-induced murine asthma model. The sensitization of wild-type (WT) and TG mice was similar as judged by the content of OVA-specific IgE. After OVA challenge, PGD(2), but not PGE(2), substantially increased in the lungs of WT and TG mice with greater PGD(2) increment in TG mice compared with WT mice. The numbers of eosinophils and lymphocytes in the bronchoalveolar lavage (BAL) fluid were significantly greater in TG mice than in WT mice on days 1 and 3 post-OVA challenge, whereas the numbers of macrophages and neutrophils were the same in both WT and TG mice. The levels of IL-4, IL-5, and eotaxin in BAL fluid were also significantly higher in TG mice than in WT mice, although the level of IFN-gamma in the BAL fluid of TG mice was decreased compared with that in WT mice. Furthermore, lymphocytes isolated from the lungs of TG mice secreted less IFN-gamma than those from WT mice, whereas IL-4 production was unchanged between WT and TG mice. Thus, overproduction of PGD(2) caused an increase in the levels of Th2 cytokines and a chemokine, accompanied by the enhanced accumulation of eosinophils and lymphocytes in the lung. These results indicate that PGD(2) plays an important role in late phase allergic reactions in the pathophysiology of bronchial asthma.

Animals↗
PubMed2002

Lipocalin-type and hematopoietic prostaglandin D synthases as a novel example of functional convergence.

Prostaglandin (PG) D2 is a major PG produced in the central nervous system and is involved in the regulation of sleep and pain responses through DP receptors. It is also actively produced by mast cells, basophils, and Th2 cells, acting as an allergic mediator through DP and CRTH2 receptors. PGD2 is further dehydrated to produce PGJ2, delta12-PGJ2, and 15-deoxy-delta(12,14)-PGJ2, the last being a ligand for the nuclear receptor PPARgamma. PGD synthase (PGDS) catalyzes the isomerization of PGH2 to PGD2 in the presence of sulfhydryl compounds. Two distinct types of PGDS have been identified: one is the lipocalin-type PGDS (L-PGDS); and the other, the hematopoietic PGDS (H-PGDS). We isolated the human and mouse cDNAs and genes for L-PGDS and H-PGDS, determined their X-ray crystallographic structures, examined their tissue distribution profiles and cellular localization, and generated gene-knockout mice and human enzyme-overexpressing transgenic mice. L-PGDS and H-PGDS are quite different from each other, in terms of their amino acid sequence, tertiary structure, evolutional origin, chromosomal and cellular localization, tissue distribution, and also functional relevance. Therefore, L-PGDS and H-PGDS are considered to be a novel example of functional convergence.

Animals↗