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Y Sugimoto

Publications and source records attributed to Y Sugimoto.

At least 325 records · Page 18Linked to original sources
PubMed1994

Enhancement of adenylate cyclase stimulation by prostaglandin E receptor EP3 subtype isoforms with different efficiencies.

We recently cloned the mouse prostaglandin (PG) E receptor EP3 subtype that is coupled to adenylate cyclase inhibition through Gi and identified two isoforms of EP3, EP3 alpha and EP3 beta, which are produced through alternative splicing and differ only in the carboxyl-terminal domain. Preincubation of Chinese hamster ovary cells expressing each isoform with PGE2 concentration-dependently enhanced both the basal and forskolin-stimulated cAMP formation, but two orders higher concentrations of PGE2 were required for EP3 beta than EP3 alpha for 50% enhancement of both formations. This enhancement by EP3 isoforms was completely blocked by pertussis toxin treatment, indicating that it is mediated through Gi activation. Thus, the two EP3 isoforms with different carboxyl-terminal tails induce enhancement of adenylate cyclase stimulation with different efficiencies.

Adenylate Cyclase Toxin↗
PubMed1994

Molecular cloning and expression of rat prostaglandin E receptor EP2 subtype.

A cDNA clone encoding the rat prostaglandin (PG) E receptor EP2 subtype was cloned from a rat lung cDNA library. It encodes 488 amino acid residues with putative seven-transmembrane domains. Specific binding of [3H]PGE2 was found in COS-7 cells transfected with the cDNA and was displaced with unlabeled prostaglandins in the order of PGE2 = PGE1 >> iloprost > or = PGF2 alpha > or = PGD2. The binding was also inhibited by misoprostol, an EP2 and EP3 agonist, but not by sulprostone, an EP1 and EP3 agonist. Northern blot analysis demonstrated that the EP2 mRNA is widely expressed in various tissues, the significant expression being observed in the thymus, lung, spleen, heart stomach, and pancreas.

Amino Acid Sequence↗
PubMed1994

Cloning and expression of a cDNA for the human prostacyclin receptor.

A functional cDNA for the human prostacyclin receptor was isolated from a cDNA library of CMK cells, a human megakaryocytic leukaemia cell line. The cDNA encodes a protein consisting of 386 amino acid residues with seven putative transmembrane domains and a deduced molecular weight of 40,956. [3H]Iloprost specifically bound to the membrane of CHO cells stably expressing the cDNA with a Kd of 3.3 nM. This binding was displaced by unlabelled prostanoids in the order of iloprost = cicaprost >> carbacyclin > prostaglandin E1 (PGE1) > STA2. PGE2, PGD2 and PGF 2 alpha did not inhibit it. Iloprost in a concentration-dependent manner increased the cAMP level and generated inositol trisphosphate in these cells, indicating that this human receptor can couple to multiple signal transduction pathways.

Amino Acid Sequence↗
PubMed1994

cDNA cloning of a mouse prostacyclin receptor. Multiple signaling pathways and expression in thymic medulla.

A functional cDNA for a mouse prostacyclin receptor was isolated from a mouse cDNA library by reverse transcription polymerase chain reaction and hybridization screening. The cDNA encodes a polypeptide of 417 amino acid residues with putative seven transmembrane domains and an calculated molecular weight of 44,722. The amino acid sequence is 30-40% identical in the transmembrane domains to those of the mouse prostaglandin (PG) E receptor subtypes and thromboxane A2 receptor. [3H]Iloprost, a specific prostacyclin receptor radioligand, specifically bound to the membrane of Chinese hamster ovary cells permanently expressing the cDNA with Kd of 4.6 nM. This binding was displaced with unlabeled prostanoids in the order of cicaprost > iloprost, both prostacyclin agonists > PGE1 > carbacyclin >> PGD2 approximately STA2, a thromboxane A2 agonist approximately PGE2 > PGF2 alpha. Iloprost in a concentration-dependent fashion increased cAMP level and generated inositol phosphates in these cells, indicating that the receptor couples to multiple signal transduction pathways. Northern blot analysis revealed that the mRNA is expressed most abundantly in thymus, followed by spleen, heart, and lung. In situ hybridization of thymus showed that it is expressed exclusively in medulla and not in cortex.

Amino Acid Sequence↗
PubMed1994

Cloning and expression of a cDNA for mouse prostaglandin F receptor.

A functional cDNA clone for mouse prostaglandin (PG) F receptor was isolated from a mouse cDNA library using polymerase chain reaction based on the sequence of cloned prostanoid receptors, and cross-hybridization screening. The mouse PGF receptor consists of 366 amino acid residues with putative seven transmembrane domains. The sequence revealed the highest homology to the EP1 subtype of PGE receptor and thromboxane (TX) A2 receptor. Ligand binding studies using membranes of COS cells transfected with the cDNA revealed specific [3H]PGF2 alpha binding. The binding was displaced with unlabeled PGs in the order of PGF2 alpha = 9 alpha, 11 beta PGF2 > PGF 1 alpha > PGD2 > STA2 (a stable TXA2 agonist) > PGE2 > iloprost (a stable PGI2 agonist). PGF2 alpha increased inositol trisphosphate formation in a concentration-dependent manner in COS cells expressing PGF receptor. RNA blot and in situ hybridization analyses demonstrated that the PGF receptor transcripts are abundantly expressed in luteal cells of corpus luteum and in a lesser amount in kidney, heart, stomach, and lung.

Amino Acid Sequence↗
PubMed1994

Mapping of the genes encoding mouse thromboxane A2 receptor and prostaglandin E receptor subtypes EP2 and EP3.

Thromboxane A2 (TXA2) and prostaglandin E2 (PGE2) are two of the most representative eicosanoids that are formed from arachidonic acid. They produce a broad spectrum of biological effects mediated through specific cell surface receptors. We have mapped genetic loci for TXA2 receptor, Tbxa2r, and for PGE2 receptor subtypes EP2 and EP3, Ptgerep2 and Ptgerep3, respectively, using restriction fragment length variants in interspecific backcross mice. None of the three loci cosegregated with each other. Tbxa2r mapped to Chr 10, Ptgerep2 mapped to the distal end of Chr 3. Possible human loci for these receptors are predicted based on the homology between mouse and human chromosomes.

Animals↗
PubMed1994

Mechanism of the vasodilatory action of nicorandil on coronary circulation in dogs.

Nicorandil possesses hybrid properties as a nitrate and a potassium (K) channel opener. We have previously reported that large coronary arteries responded to nicorandil at low plasma concentrations, while dilatation of small coronary arteries only occurred at higher plasma concentrations (above 200 ng/ml) in chronically instrumented dogs. In this study we examined the effects of intravenous nicorandil on epicardial coronary artery diameter (CoD) and coronary blood flow (CBF) in the absence and presence of glibenclamide, a K+ channel blocker, as well as the effects of nitroglycerin and cromakalim as reference drugs. The increase in CBF induced by nicorandil and cromakalim was significantly suppressed by glibenclamide. However, the increase in CoD induced by nicorandil and nitroglycerin was not suppressed by glibenclamide. These findings suggest that nicorandil-induced dilatation of the large coronary arteries was related to its nitrate action, while nicorandil-induced dilatation of the small coronary arteries was closely related to its effect as a K+ channel opener. In addition, the former response to nicorandil occurred at low concentrations, while the latter occurred at higher concentrations.

Animals↗
PubMed1994

Effects of tryptamine on plasma glucagon levels in mice.

Our previous study indicated that tryptamine induces a dose-related increase in plasma glucagon levels of mice and that this effect is mediated by the peripheral serotonin2 (5-HT2) receptor. The present paper further investigated the involvement of serotonergic and catecholaminergic systems in hyperglucagonemia elicited by tryptamine. An inhibitor of 5-HT synthesis, p-chlorophenylalanine, did not affect tryptamine-induced increases in plasma glucagon levels. Tryptamine-induced hyperglucagonemia was not inhibited by adrenalectomy or by an inhibition of catecholamine synthesis by alpha-methyl-p-tyrosine. These findings indicate that tryptamine-induced hyperglucagonemia is elicited by its direct activation of 5-HT2 receptors and is not mediated by levels of endogenous 5-HT and catecholamines. The results further suggest that the peripheral 5-HT2 receptor has a possible role in the release of glucagon.

Adrenalectomy↗
PubMed1994

Inhibitory effects of tryptamine on tolbutamide-induced hypoglycemia in mice: mediation by 5-HT receptors.

Effects of tryptamine on tolbutamide-induced hypoglycemia were investigated in mice. Tryptamine significantly inhibited hypoglycemia elicited by tolbutamide. The inhibitory effects of tryptamine were strongly blocked by the 5-HT1 and 5-HT2 receptor antagonist methysergide and the 5-HT2 receptor antagonist ketanserin, while the 5-HT3 receptor antagonist ICS 205-930 was without effect. Tryptamine induced hyperglucagonemia in tolbutamide-treated mice, and this effect elicited by tryptamine was strongly inhibited by the 5-HT2 receptor antagonist ketanserin. These results suggest that the inhibitory effects of tryptamine on tolbutamide-induced hypoglycemia are mediated by 5-HT2 receptors and that tryptamine is involved in glucagon release.

Animals↗
PubMed1994

Thyroid imaging in a typical case of acute suppurative thyroiditis with abscess formation due to infection from a persistent thyroglossal duct.

The clinical evaluation of thyroid imaging with 99mTc, 201Tl, and 67Ga in the uncommon, but potentially serious, disorder of acute suppurative thyroiditis (AST) with abscess formation due to infection from a persistent thyroglossal duct is reported. The 99mTc image showed functioning areas of the diseased thyroid gland and the 201Tl image demonstrated abscess formation in the thyroid gland of this patient. In addition, marked 67Ga accumulation was demonstrated in a wide area covering not only the area of the thyroid gland involved, but also associated circumferential inflammatory lesions in a patient with AST. The net thyroid uptake of 67Ga at 72 hours was calculated to be 13.8% of the injected dose.

Abscess↗
PubMed1994

TEI-3356, a highly selective agonist for the prostaglandin EP3 receptor.

Recently, we cloned cDNAs for the three mouse PGE receptor subtypes, EP1, EP2 and EP3, and the prostacyclin receptor, and established cells that stably express each receptor. We examined the selectivity of TEI-3356, an isocarbacyclin analogue, compared with other EP agonists, sulprostone and misoprostol, using Chinese hamster ovary cells expressing each cloned receptor. TEI-3356 selectively displaced the [3H]PGE2 binding to EP3-expressing cell membranes, but showed very low affinity for both EP1 and EP2. Although TEI-3356 is an isocarbacyclin analogue, it showed low affinity for the prostacyclin receptor. On the other hand, sulprostone strongly displaced the [3H]PGE2 binding to EP1 and EP3, but not to EP2. Misoprostol weakly bound to the three subtypes without selectivity. TEI-3356 decreased the forskolin-induced cAMP formation in a concentration-dependent manner in the EP3-expressing cells, the half-maximal concentration for the inhibition being similar to that of sulprostone but lower than that of PGE2. These results demonstrate that TEI-3356 is a potent and highly selective agonist for the EP3 receptor.

Animals↗
PubMed1994

Cloning and expression of a cDNA for rat prostaglandin F2 alpha receptor.

We have cloned a cDNA for rat prostaglandin (PG) F2 alpha receptor from cultured rat astrocytes. The cDNA encodes a polypeptide of 366 amino acids with seven putative transmembrane domains. Specific binding of [3H]PGF2 alpha in membranes of COS-7 cells transfected with the cDNA was displaced with unlabeled PGs in the order of PGF2 alpha > PGD2 > PGE2 > PGI2. In the cDNA-transfected LLC-PK1 cells, PGF2 alpha stimulated phosphoinositide hydrolysis. A significant 4.7-kb mRNA transcript was detected in cultured rat astrocytes and whole brain and pregnant ovary of adult rats by Northern blot analysis.

Amino Acid Sequence↗
PubMed1994

Distribution of the messenger RNA for the prostaglandin E receptor subtype EP3 in the mouse nervous system.

Distribution of the messenger RNA for the prostaglandin E receptor subtype EP3 was investigated by in situ hybridization in the nervous system of the mouse. The hybridization signals for EP3 were widely distributed in the brain and sensory ganglia and specifically localized to neurons. In the dorsal root and trigeminal ganglia, about half of the neurons were labeled intensely. In the brain, intensely labeled neurons were found in Ammon's horn, the preoptic nuclei, lateral hypothalamic area, dorsomedial hypothalamic nucleus, lateral mammillary nucleus, entopeduncular nucleus, substantia nigra pars compacta, locus coeruleus and raphe nuclei. Moderately labeled neurons were seen in the mitral cell layer of the main olfactory bulb, layer V of the entorhinal and parasubicular cortices, layers V and VI of the cerebral neocortex, nuclei of the diagonal band, magnocellular preoptic nucleus, globus pallidus and lateral parabrachial nucleus. In the thalamus, moderately labeled neurons were distributed in the anterior, ventromedial, laterodorsal, paraventricular and central medial nuclei. Based on these distributions, we suggest that EP3 not only mediates prostaglandin E2 signals evoked by blood-borne cytokines in the areas poor in the blood-brain barrier, but also responds to those formed intrinsically within the brain to modulate various neuronal activities. Possible EP3 actions are discussed in relation to the reported neuronal activities of prostaglandin E2 in the brain.

Animals↗
PubMed1994

X-ray diffraction evidence for the extensibility of actin and myosin filaments during muscle contraction.

To clarify the extensibility of thin actin and thick myosin filaments in muscle, we examined the spacings of actin and myosin filament-based reflections in x-ray diffraction patterns at high resolution during isometric contraction of frog skeletal muscles and steady lengthening of the active muscles using synchrotron radiation as an intense x-ray source and a storage phosphor plate as a high sensitivity, high resolution area detector. Spacing of the actin meridional reflection at approximately 1/2.7 nm-1, which corresponds to the axial rise per actin subunit in the thin filament, increased about 0.25% during isometric contraction of muscles at full overlap length of thick and thin filaments. The changes in muscles stretched to approximately half overlap of the filaments, when they were scaled linearly up to the full isometric tension, gave an increase of approximately 0.3%. Conversely, the spacing decreased by approximately 0.1% upon activation of muscles at nonoverlap length. Slow stretching of a contracting muscle increased tension and increased this spacing over the isometric contraction value. Scaled up to a 100% tension increase, this corresponds to a approximately 0.26% additional change, consistent with that of the initial isometric contraction. Taken together, the extensibility of the actin filament amounts to 3-4 nm of elongation when a muscle switches from relaxation to maximum isometric contraction. Axial spacings of the layer-line reflections at approximately 1/5.1 nm-1 and approximately 1/5.9 nm-1 corresponding to the pitches of the right- and left-handed genetic helices of the actin filament, showed similar changes to that of the meridional reflection during isometric contraction of muscles at full overlap. The spacing changes of these reflections, which also depend on the mechanical load on the muscle, indicate that elongation is accompanied by slight changes of the actin helical structure possibly because of the axial force exerted by the actomyosin cross-bridges. Additional small spacing changes of the myosin meridional reflections during length changes applied to contracting muscles represented an increase of approximately 0.26% (scaled up to a 100% tension increase) in the myosin periodicity, suggesting that such spacing changes correspond to a tension-related extension of the myosin filaments. Elongation of the myosin filament backbone amounts to approximately 2.1 nm per half sarcomere. The results indicate that a large part (approximately 70%) of the sarcomere compliance of an active muscle is caused by the extensibility of the actin and myosin filaments; 42% of the compliance resides in the actin filaments, and 27% of it is in the myosin filaments.

Actins↗
PubMed1994

Ketoconazole effectively reverses multidrug resistance in highly resistant KB cells.

The antifungal agent ketoconazole was found to overcome resistance to vinblastine and doxorubicin in multidrug resistant KB-V1 cells in vitro. These cells are several hundred-fold more resistant than the parental cell line KB-3-1. Ketoconazole had little or no effect on the parental KB-3-1 cells. The concentrations used to overcome drug resistance in vitro have already been safely used in vivo for treatment of fungal infections and in the monotherapy of hormone independent prostate carcinomas to block adrenal androgen production. Because of a possible beneficial effect of a combination of ketoconazole and a chemotherapeutic drug in multidrug resistant cancers, we examined a panel of 11 prostate carcinoma tissues for the expression of the MDR1 gene by an RNA-PCR assay. MDR1 expression was detectable, albeit at low levels, in 8 of the 11 tumors, suggesting a possible role of this gene in the drug resistance of prostate carcinomas. Our data suggest that ketoconazole might be useful in overcoming multidrug resistance in concentrations that are achievable in humans.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Efficient expression of drug-selectable genes in retroviral vectors under control of an internal ribosome entry site.

We describe a new retroviral vector system pSXLC/pHa that utilizes a putative internal ribosome entry site (IRES) from encephalomyocarditis virus downstream from a multicloning site to co-express drug-selectable markers with a second non-selectable cDNA in a eukaryotic expression vector. The positive drug-selectable marker, MDR1, and the positive-negative marker, herpes simplex virus thymidine kinase (HSV-TK), were successfully introduced and expressed in the pSXLC/pHa system. The pSXLC-MDR and pSXLC-TK vectors contain the drug-selectable genes under translational control of the IRES and multiple cloning sites upstream for insertion of second cDNAs which can be co-expressed in this system. The inserts of these pSXLC plasmids were designed for easy transfer to the pHa retrovirus vector which has a strong promoter from Harvey murine sarcoma virus. The IRES-MDR-carrying retroviral vector, pHa-MCS-IRES-MDR, conferred resistance to vincristine and adriamycin. The IRES-TK-containing vector, pHa-MCS-IRES-TK conferred HAT-resistance in TK-deficient cells and the transfectants showed hypersensitivity to ganciclovir. These "flexible" vectors should be useful for co-expression of genes for selectable gene transfer and for positive-negative (suicide) selections in vitro and in vivo.

3T3 Cells↗