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Naomi Eguchi

Publications and source records attributed to Naomi Eguchi.

11 recordsLinked to original sources
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↗
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

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

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↗
PubMed2002

Endogenous prostaglandin D2 synthesis reduces an increase in plasminogen activator inhibitor-1 following interleukin stimulation in bovine endothelial cells.

OBJECTIVE: We examined the role of prostaglandin D2 (PGD2) in the formation of plasminogen activator inhibitor (PAI)-1 following interleukin-1beta (IL-1) stimulation in bovine endothelial cells (EC) transfected with lipocaline-type PGD2 synthase (L-PGDS) genes. DESIGN AND METHODS: EC were isolated from bovine thoracic aorta and incubated with 20 U/ml IL-1 and various concentrations of authentic PGD2. The isolated EC were also transfected with L-PGDS genes by electroporation. The L-PGDS-transfected EC were used to investigate the role of endogenous PGD2 in IL-1 stimulated PAI-1 biosynthesis. We also used an anti-PGD2 antibody to examine whether an intracrine mechanism was involved in PAI-1 production. PGD2 and PAI-1 levels were determined by radio- and enzyme-immunoassay, respectively. PAI-1 mRNA was assessed by reverse transcription-polymerase chain reaction. RESULT: IL-1 stimulated PAI-1 production by EC was dose-dependently inhibited by authentic PGD2 at concentrations greater than 10-6 mol/l. L-PGDS gene-transfected EC produced more PGD2 than EC transfected with the reporter gene alone. IL-1 induced increases in PAI-1 production in EC transfected with reporter genes alone. However, this effect was significantly attenuated in the case of IL-1 stimulation of EC transfected with L-PGDS genes, and accompanied by an apparent suppression of PAI-1 mRNA expression. The effects of PGD2 on PAI-I formation were reversed to the basal levels by the inhibition of synthesis of endogenous PGD2. Neutralization of extracellular PGD2 by anti-PGD2 antibody influenced neither PAI-1 mRNA expression nor PAI-1 biosynthesis. CONCLUSION: EC transfected with L-PGDS genes increased PGD2 synthesis. This was associated with attenuation of both PAI-1 formation and PAI-1 mRNA expression. It is suggested that endogenous PGD2 decreases PAI-1 synthesis and PAI-1 mRNA expression, probably through an intracrine mechanism.

Animals↗
PubMed2002

Blood sugar control reverses the increase in urinary excretion of prostaglandin D synthase in diabetic patients.

BACKGROUND/AIMS: We investigated basal levels of serum and urinary lipocalin-type prostaglandin D synthase/beta-trace (L-PGDS) in type-2 diabetic patients and explored whether glycemic control affects L-PGDS status in another 55 diabetic inpatients with normoalbuminuria. METHODS: Fifty-five type-2 diabetic outpatients (HbA1c, 9.14 +/- 0.20%; creatinine (Cr), 85.1 +/- 2.4 micromol/l), and 55 age-matched healthy control subjects were recruited. Serum and urinary levels of L-PGDS were determined with respect to the stage of diabetic nephropathy. The L-PGDS was localized by immunohistochemistry. RESULTS: The urinary L-PGDS index increased in diabetic patients, compared with the controls (234.8 +/- 27.4 vs. 73.8 +/- 7.8 microg/mmol Cr, p < 0.001). Even in normoalbuminuric patients as well as in microalbuminuric patients, urinary L-PGDS indexes were higher than the controls (166.0 +/- 21.1, p < 0.0001 and 338.6 +/- 62.5 microg/mmol Cr, p < 0.0001, respectively), although the serum L-PGDS level was equal to that in the control subjects. Multiple regression analysis revealed that the urinary L-PGDS index was predicted solely by glucose levels and type-IV collagen index, whereas the serum L-PGDS was determined mainly by age and serum Cr. Glycemic control reduced the urinary L-PGDS index towards the normal range in diabetic patients with normoalbuminuria (172.3 +/- 6.6 vs. 118.1 +/- 2.6 (SE) microg/mmol Cr, p < 0.0001). Immunohistochemistry showed that L-PGDS was uniquely present in the renal tubules in diabetes while in nondiabetics, L-PGDS occurred solely in the peritubular interstitium, not in the tubular cells. CONCLUSION: Inadequate glycemic control is responsible for urinary L-PGDS excretion in the diabetic patients. Urinary L-PGDS is useful to predict subclinical renal injury associated with type-2 diabetes.

Adult↗
PubMed2002

Immunohistochemical localization of microsomal PGE synthase-1 and cyclooxygenases in male mouse reproductive organs.

We investigated the tissue distribution and cellular localization of microsomal PGE synthase-1 (mPGES-1) and cyclooxygenase (COX)-1 and -2 in the male mouse reproductive organs. Northern blotting revealed that the mPGES-1 mRNA was expressed intensely in the epididymis and weakly in the lung, spleen, skin, kidney, colon, and brain. In the male reproductive tract, the expression of mPGES-1 increased from the testis to the cauda epididymis and was highest in the vas deferens when examined by Northern blotting, RT-PCR, and Western blotting. By immunohistochemistry, mPGES-1 was detected in Leydig cells of the testis and in epithelial cells of the epididymis, vas deferens, and seminal vesicles. In addition, the caput and cauda regions of the epididymis and the vas deferens in this order showed a progressive increase in the expression of COX-1 mRNA and immunoreactivity, whereas COX-2 was dominantly expressed in the vas deferens. COX-1 was localized in epithelial cells of the caput, corpus and cauda epididymis and of the vas deferens, and COX-2 was evident in epithelial cells of the distal cauda epididymis and vas deferens. These results show that mPGES-1 is expressed coordinately with COX-1 and COX-2 and is involved in PGE(2) production in male genital organs.

Animals↗
PubMed2002

Development and evaluation of a practical ELISA for human urinary lipocalin-type prostaglandin D synthase.

BACKGROUND: Urinary excretion of lipocalin-type prostaglandin D synthase (L-PGDS) is significantly increased in patients with chronic renal failure, but its diagnostic potential in less advanced stages of renal diseases remains to be elucidated. METHODS: Six mouse monoclonal antibodies (MAbs) were raised against recombinant human L-PGDS. We constructed a sandwich ELISA with two MAbs that recognized different epitopes with high affinities and assessed its assay performance and clinical utility with urine samples from healthy controls, diabetic patients, and patients with various renal diseases. RESULTS: Western blot analyses with NH(2)-terminus-truncated L-PGDS mapped the epitopes to Ala(23)-Val(28) (MAb-7F5 and -10A3), Ser(52)-Ala(73) (MAb-9A6), Tyr(107)-Val(120) (MAb-1B7 and -6F5), and Gly(140)-Pro(155) (MAb-6B9). A sandwich ELISA was constructed with MAb-1B7 and -7F5, the K(d) values of which were 3.6 and 3.9 nmol/L, respectively, for native L-PGDS. Recoveries were 91-111%, and intra- and interassay CVs were <6% and <9%, respectively. The ELISA showed parallelism of standard and urine samples and no significant interference by a variety of urinary constituents. Urinary L-PGDS excretion was significantly increased in patients with diabetic nephropathy, IgA nephropathy, and chronic glomerulonephritis even when serum creatinine was not increased. In patients with renal diseases, urinary L-PGDS was correlated with urinary albumin (r = 0.64; P <0.0001), N-acetyl-beta-D-glucosaminidase (r = 0.43; P <0.001), and serum creatinine (r = 0.66; P <0.0001). At a cutoff value of 284 mg/mol creatinine, the assay had sensitivities of 74% for diabetic nephropathy and 83% for chronic glomerulonephritis and a specificity of 93%. CONCLUSIONS: This ELISA system is suitable for measurement of urinary L-PGDS in a routine clinical assay and may be useful to detect less advanced stages of renal diseases.

Animals↗