Biomedical subjects

S Hirose

Publications and source records attributed to S Hirose.

At least 253 records · Page 14Linked to original sources

PubMed1995

Cloning and properties of a novel natriuretic peptide receptor, NPR-D.

A novel natriuretic peptide receptor, which we have termed natriuretic peptide receptor D (NPR-D), has been cloned and characterized. cDNAs related to the natriuretic peptide receptor (NPR) were amplified by PCR from a template of poly(A)-rich RNA isolated from the eel gill. Sequencing of the PCR products revealed the presence of a new clone that showed about 70% sequence identity to the eel type-C receptor, NPR-C. The PCR fragment was used to determine the tissue distribution of the new NPR-D message by an RNase protection assay, which gave the strongest signal in brain samples, and then used to screen a brain library to obtain a full-length cDNA clone. The cDNA clone predicted a protein of 500 amino acids containing a signal sequence and a hydrophobic transmembrane segment. The predicted sequence also contained the NPR motif which is essential for the binding of natriuretic peptides. The protein NPR-D was expressed in COS cells and shown to have high affinities for eel and rat natriuretic peptides. The newly cloned NPR-D has a short cytoplasmic tail; in this respect, NPR-C and NPR-D are very similar and form a subfamily of the NPR family. Affinity labeling indicated that NPR-D exists as a disulfide-linked tetramer. This is a marked contrast to the homodimeric structure of NPR-C. HS-142-1, a non-peptide natriuretic peptide receptor antagonist of microbial origin previously shown to be selective for the guanylate-cyclase-coupled receptors NPR-A and NPR-B, competitively inhibited the binding of 125I-labeled eel natriuretic peptide to eel NPR-D, whereas it did not affect the binding activity of eel NPR-C, suggesting that HS-142-1 is an antagonist that recognizes the tetrameric structures of NPR since the guanylate-cyclase-coupled receptors have also been demonstrated to exist as tetramers.

Amino Acid Sequence↗

PubMed1995

Cloning, characterization, and tissue distribution of porcine SPAI, a protein with a transglutaminase substrate domain and the WAP motif.

The primary and gene structures and tissue distribution of porcine SPAI-2, a protein that belongs to the WAP protein superfamily and has a sodium-potassium ATPase inhibitory activity, were determined by molecular cloning and Northern analysis. A full-length cDNA clone was isolated from a porcine duodenum cDNA library. The cDNA insert encoded a polypeptide of 187 amino acids, which is composed of three domains: a hydrophobic presequence of 21 amino acids, a prosegment of 105 amino acids ending with Asp126, and the mature SPAI-2 sequence of 61 amino acids beginning with Pro127. The prosegment contained 16 repeats of a hexapeptide that is highly homologous to the repetitive sequence found in the transglutaminase domain of the human elafin, an elastase-specific inhibitor that also belongs to the WAP superfamily. The repetitive sequence was demonstrated to be a good substrate of transglutaminase using a recombinant preparation produced in Escherichia coli. A porcine genomic library was then screened for the SPAI gene. Characterization and sequencing of positive clones indicated that the gene is similar to the elafin gene, having 3 exons encoding the 5'-untranslated region and signal sequence, proSPAI, and 3'-untranslated region, respectively. Northern blot analysis revealed intestine-specific expression of SPAI mRNA; the message was especially abundant in the small intestine. ProSPAI was also found in the circulation. The similarity of proSPAI to elafin in the domain structure, the acid-labile nature of the cleavage site (Asp126-Pro127), and the fact that the major form of SPAI in the plasma is proSPAI strongly suggest that proSPAI is not the precursor but rather it is the native form of SPAI. Like elafin, therefore, SPAI appears to be a new type of biologically active substance with a transglutaminase substrate domain that acts as an anchoring sequence.

Amino Acid Sequence↗

PubMed1995

Cloning of a cDNA for DNA supercoiling factor reveals a distinctive Ca(2+)-binding protein.

DNA supercoiling factor is a protein capable of generating negative supercoils into a relaxed DNA in conjunction with eukaryotic DNA topoisomerase II. A cDNA clone encoding the Bombyx mori supercoiling factor has been isolated and characterized. The cDNA sequence contains an open reading frame of 322 amino acids rich in acidic residues. A local region of the predicted polypeptide shares a weak homology with the central portion of bacterial DNA gyrase A subunit. The cDNA sequence also predicts two direct repeats within the factor. Each repeat unit consists of a potential EF-hand domain. The factor contains three other potential EF-hand domains and actually binds Ca2+. Moreover, the supercoiling reaction has been shown to be activated by Ca2+. These results implicate Ca2+ in the control of the superhelical state of DNA.

Amino Acid Sequence↗

PubMed1995

Sequences of two cDNAs encoding silkworm homologues of Drosophila melanogaster squid gene.

The squid (sqd) gene of Drosophila melanogaster encodes a few isoforms of a heterogeneous nuclear (hn) RNA-binding protein. We isolated two types of cDNAs coding for homologues of the Sqd protein from the silkworm Bombyx mori. The two predicted amino acid (aa) sequences are identical up to aa 280 and then diverge. The silkworm and fruit fly proteins share 80% homology in the RNA-binding motif region. These cDNAs detect 2.0-, 1.8- and 1-kb mRNAs in the middle and posterior silk glands.

Alternative Splicing↗

PubMed1995

Cloning, properties, site-directed mutagenesis analysis of the subunit structure, tissue distribution and regulation of expression of the type-C eel natriuretic peptide receptor.

Eel natriuretic peptide receptor C (NPR-C) was cloned, characterized and found to have a unique interchain disulfide linkage when compared to that of mammalian NPR-C. The NPR-C cDNA was obtained from an eel gill cDNA library; the open reading frame codes for a polypeptide of 502 amino acids exhibiting the known features of NPR-C, including a weak ligand specificity and a disulfide-linked homodimeric structure. The deduced amino acid sequence shares approximately 60% similarity with the mammalian NPR-C but it lacks the Gly-rich prosequence present in the mammalian counterparts. Site-directed mutagenesis revealed that eel and mammalian NPR-C are quite different in their interchain disulfide-bonding pattern; eel uses the second Cys residue and mammals the fifth Cys residue for the covalent dimerization. The ligand-binding activity of the extracellular domain is not independent of the short cytoplasmic tail. RNase protection analysis revealed that the eel receptor is highly expressed in the gill and heart and, to a much lesser extent, in other tissues including the brain and intestine. The NPR-C mRNA levels were found to be down-regulated in most tissues when eels were transferred from fresh water to seawater; however, in the anterior intestine, the levels were up-regulated, suggesting that NPR-C plays a role in the adaptation to salinity changes in the euryhaline eel.

Amino Acid Sequence↗

PubMed1995

Effects of shear stress on glycosaminoglycan synthesis in vascular endothelial cells.

Glycocalyx on the surface of endothelium has been suggested to be involved in vascular permeability and anticoagulation. In the present study, we demonstrated that fluid laminar shear stress enhanced a glycosaminoglycan (GAG) synthesis in porcine aortic endothelial cells, in vitro. Shear stress (15, 40 dyn/cm2) for 24 hours significantly increased GAG synthesis, assayed by [35S]sulfate incorporation, in "medium" fraction and "trypsinated" fraction which includes GAGs derived from the cell surface and from the solubilized matrix. Increased GAGs in the trypsinated and medium fractions consisted of mainly heparan sulfate and chondroitin/dermatan sulfate, respectively. Both heparan and chondroitin/dermatan sulfate increases are required to expose the cells to shear stress for more than 24 hours. Shear-stress-induced increase in GAG synthesis was concomitant with a decrease in DNA synthesis and an increase in protein synthesis. These data indicate that relatively high shear stress may suppress atherogenesis by changing endothelial GAG synthesis.

Animals↗

PubMed1995

Cholesterol metabolism in monocyte-derived macrophages from macrophage colony-stimulating factor administered rabbits.

The metabolism of beta-very-low-density lipoproteins (beta-VLDL) in macrophages from the blood monocytes of rabbits, which had been administered macrophage colony-stimulating factor (M-CSF) in vivo, was investigated in order to clarify the mechanism of the suppressive effect of M-CSF on cholesterol accumulation in macrophages. Cholesterol ester content after incubation with beta-VLDL, and [3H]cholesterol oleate-beta-VLDL incorporation remarkably increased in cultured macrophages from blood monocytes in the high cholesterol diet control group compared to those in the normal diet control group. Those in macrophages from M-CSF-treated groups, both normal diet and high cholesterol diet, were the same as in the normal diet control group. The ratio of released [3H]cholesterol to incorporated [3H]cholesterol oleate-beta-VLDL in macrophages from control was smaller than that from the M-CSF group. The acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity was enhanced in the high cholesterol diet groups, and the activity in M-CSF-treated groups decreased. The neutral cholesterol esterase activity was enhanced in the M-CSF-treated groups compared with that in the non-treated control groups. These results suggest that high cholesterol diet induced further cholesterol esterification and that M-CSF treatment enhanced cholesterol clearance in macrophages.

Animals↗

PubMed1995

Preferential dependence of autoantibody production in murine lupus on CD86 costimulatory molecule.

Blockade of the interactions between CD28/CTLA-4 and their ligands, CD80 (B7, B7.1)/CD86 (B70, B7.2), seems an attractive means to induce antigen-specific peripheral tolerance in organ transplantation and autoimmune disease. Recently, diversities between CD80 and CD86 in expression, regulation, and function have been reported in certain cell populations and murine experimental disease models. To investigate the possible differential role of CD80 and CD86 in the development of lupus, we treated lupus-prone NZB/W F1 mice with specific monoclonal antibodies (mAb) against CD80, CD86, or both. The treatment with a combination of anti-CD80 and CD86 mAb before the onset of lupus completely prevented autoantibody production and nephritis, and prolonged survival. Interestingly, we found that anti-CD86 mAb alone, but not anti-CD80 mAb, efficiently inhibited autoantibody production. Subclass study on IgG anti-double-stranded (ds) DNA antibody revealed that the treatment with anti-CD86 mAb almost completely inhibited both IgG1 and IgG2b, but not IgG2a production. The incomplete reduction of IgG2a anti-dsDNA antibody by anti-CD86 mAb was compensated by the addition of anti-CD80 mAb. A significant reduction of mRNA for interleukin (IL)-2, interferon-gamma, IL-4 and IL-6 was observed in mice treated with a combination of anti-CD80 and CD86 mAb or anti-CD86 mAb alone. Treatment with both mAb after the onset of lupus resulted in a significantly prolonged survival with reduction of autoantibody production. These results suggest that CD86 plays a more critical role in autoantibody production, and CD86, but not CD80, contributes to Th2-mediated Ig production. However, the blockade of both CD80 and CD86 are required for preventing the development and progression of lupus.

Animals↗

PubMed1995

Abnormal T cell activation and skewed T cell receptor V beta repertoire usage in Japanese patients with idiopathic portal hypertension.

Idiopathic portal hypertension (IPH), a disorder of unknown etiology, is characterized by a noncirrhotic portal hypertension associated with splenomegaly, hypersplenism, and anemia. We examined the surface phenotypes of T cells and the T cell receptor V beta repertoire in patients with IPH. The T cells in peripheral blood samples and from spleens showed a marked increase in frequencies of HLA-DP(+)- and HLA-DR(+)-activated T cells and the observed high frequencies in the blood were to a considerable extent reduced after splenectomy. Thus, the continuous activation of T cells may occur initially in the spleen. Investigation of T cell receptor V beta repertoire revealed a significant skewing of V beta 9 and V beta 11 in both peripheral blood and splenic T cells and V beta 12 in splenic T cells. The IPH may be a disease mediated by a continuous stimulation with either a certain antigen or more likely a superantigen.

Adult↗

PubMed1995

Inhibitory effect of the immunosuppressant FK506 on apoptotic cell death induced by HIV-1 gp120.

Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 may play a central role in inducing immunoregulatory disorders after HIV infection. The apoptotic death of normal human peripheral blood mononuclear cells was induced by priming with gp120 followed by stimulation with an anti-T cell receptor (TCR) antibody. Tumor necrosis factor-alpha produced by gp120-binding macrophages may be important to induce this cell death. Treatment of gp120-primed cells with an immunosuppressant (FK506) before TCR signaling inhibited apoptotic cell death, and this blocking effect of FK506 was concentration dependent. FK506 did not have any influence on cell growth and viability over the range of concentrations tested. These findings suggest that FK506 is a potentially useful drug in delaying the onset of AIDS after HIV infection.

Antiviral Agents↗

PubMed1995

Mammalian glycosylphosphatidylinositol-anchored proteins and intracellular precursors.

Glycosylphosphatidylinositol-anchored proteins can be specifically identified by several methods. PI-PLC digestion analyses, the most widely used technique, can be performed more reliably when conducted with purified protein and phase partitioning to exclude steric effects and when combined with alkaline hydrolysis to control for inositol acylation. Reductive radiomethylation not only can definitively identify a candidate protein as being GPI anchored, but also can provide information on the number of amine components (GlcN, ethanolamine) in the anchor structure. Biosynthetic labeling with anchor precursors is relatively specific when performed with [3H]ethanolamine or [3H]inositol. Incorporation of the precursors additionally can be used to (1) document anchor transfer to primary translation products, (2) identify soluble derivatives of GPI-anchored proteins that have been released from cell surfaces, and (3) localize the site of GPI anchor attachment within a GPI-anchored protein. A pathway for mammalian GP anchor assembly is depicted in Fig. 12. Initially GlcNAc is transferred to PI. The resulting GlcNAc-PI is then deacetylated to yield GlcN-PI. After that step, several points of divergence are identifiable between the mammalian and T. brucei pathways: (1) all mammalian Man-containing intermediates are built on acylated inositol phospholipids; (2) a proximal phosphoethanolamine is found in mammalian GPI anchor intermediates and is added to Man 1 prior to incorporation of Man 2 and Man 3; (3) no Gal branching substituent is added to the mammalian core glycan; and (4) the most polar mammalian GPI contains a third phosphoethanolamine substituent linked to the 6 position of Man 2.

Acetylglucosamine↗

PubMed1995

Ruptured aneurysm associated with arachnoid cyst: intracystic hematoma without subarachnoid hemorrhage.

BACKGROUND: It is well-known that arachnoid cysts of the middle fossa are associated often with chronic subdural hematomas and/or intracystic hemorrhages. However, reports of an arachnoid cyst associated with an aneurysm are rare. CASE DESCRIPTION: A 45-year-old man was admitted with headache due to intracystic hemorrhage in the sylvian fissure, associated with a saccular aneurysm at the bifurcation of the internal carotid artery. The aneurysm ruptured into the arachnoid cyst, without causing a subarachnoid hemorrhage. Subsequently, the neck of the aneurysm was clipped successfully. The patient's postoperative course was uneventful, and there was no vasospasm. CONCLUSIONS: This is the first reported case of an intracystic hematoma due to a ruptured aneurysm. We discuss the possible etiology of the association between the aneurysm and the arachnoid cyst, and the formation mechanism for the intracystic hematoma that did not result in a subarachnoid hemorrhage.

Arachnoid Cysts↗

PubMed1995

Functional CD4+ T cell subsets defined by expression of CD45RC and NTA260 antigens and age-associated polarization in murine lupus.

Using two mAb, one specific to the alternative exon 6-dependent epitope of CD45 molecules (JH6.2) and one a natural thymocytotoxic autoantibody (NTA) with an unknown reactive epitope (NTA260), we subdivided splenic CD4+ T cells from 2-month-old BALB/c mice into five phenotypically distinct subsets. CD45RC+NTA260- (S I) cells were phenotypically analogous to CD4+ T cells predominating in newborn mice and produced a significant amount of IL-2, but not so IL-4, IL-10 or IFN-gamma when stimulated with immobilized anti-CD3 mAb in vitro. They appeared to consist mainly of naive ThP cells. The CD45RC+NTA260+ (S II) subset also produced IL-2, but not other cytokines; however, the IL-2 levels produced were much higher than seen with the S I subset, thereby suggesting the predominance of further maturated ThP cells. The CD45RC-NTA260+ (S III) subset mainly produced IL-4, IL-10, IFN-gamma and less IL-2, and contained memory cells that helped the secondary antibody response to a recall antigen, and hence contained Th2 and probably a mixture of Th0 and Th1 cells. The CD45RC-NTA260- (S IV) subset was a poor responder to the immobilized anti-CD3 mAb. The CD45RCbrightNTA260dull (S V) subset consisted of a small number of cells that were phenotypically analogous to activated CD4+ T cells. While an age-associated decrease in the proportion of S I and less markedly in S II and in turn increase in S III subsets of CD4+ T cells occurred in normal BALB/c mice, autoimmune disease-prone (NZB x NZW)F1 mice showed a marked age-associated decrease in the proportion of not only S I, II but also III subsets. As aged (NZB x NZW)F1 mice carry CD4+ T helper cells for IgG anti-DNA antibody production, such age-associated polarization to the S IV subset appears to be critical in the pathogenesis of autoimmune disease in these mice.

Aging↗

PubMed1995

Food restriction inhibits an autoimmune disease resembling systemic lupus erythematosus in (NZB x NZW) F1 mice.

To investigate the beneficial effects of food restriction on systemic lupus erythematosus in NZB x NZW F1 mice, we separated the mice into three groups. One was fed a diet in which total food intake was reduced to 60% of normal from age 2 mo onward, while the animals were still healthy (group 2R). A second group was selected at age 7 mo based on a positive lupus nephritis (proteinuria) and fed the 40% restricted diet thereafter (group 7R); a third group was allowed to consume food ad libitum (control). All control mice died of renal disease by age 14 mo, whereas all mice in group 2R and 80% of those in group 7R were living at that age. Measurements of anti-double stranded DNA antibody concentrations in sera and in supernatants of in vitro spleen cell cultures revealed that the production of the immunoglobulin G, but not immunoglobulin M, class of antibodies was markedly and significantly reduced in food-restricted mice. Age-associated changes in lymphocyte subsets seen in control mice, i.e., increases in B:T and CD4:CD8 T cell ratios, decreases in NTA260+ T cell subsets, and increases in aberrant activated NTA204+CD4+ T cells and cycling cells, were all significantly lessened in underfed mice. Food restriction did not suppress the secondary acquired antibody responses to a foreign antigen. Thus, the beneficial effects of food restriction in these mice may be related to the lessening of the age-related onset of T cell subset abnormalities, including activation of autoreactive T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Localization and characterization of a novel receptor for endothelin in the gills of the rainbow trout.

Endothelin (ET) receptors were identified in trout tissues that included the gill, heart, liver, kidney, and intestine. Since both the presence and the physiological function of endothelin-1 (ET-1) in trout gills have been determined, we examined the localization and characterization of ET receptors in the gills. Ligand specificity of the receptors, determined by using members of the endothelin family, revealed that endothelin receptors specific for ET-1 were predominant in the gills, but the binding sites of such receptors had low affinity for BQ-123, which is selective for mammalian endothelin A receptors (ETA). We propose that this subtype of receptor be called a fish-type ETA receptor (ETAF) to distinguish it from the mammalian ETA receptor. Affinity labeling of binding sites on gill membranes with 125I-labeled ET-1 and the cross-linking reagent 1,5-difluoro-2,4-dinitrobenzene revealed one major protein with an M(r) of 58,000, similar to that found in mammals. Autoradiographic studies demonstrated a high density of endothelin-binding sites in the lamellar sinusoid, which is involved in gas exchange in gills. No binding was detected in the chondrocytes or cartilaginous matrix. Our observations suggest that the endothelin and ET receptor system found in mammals might play a physiological role in the regulation of metabolic functions in fish.

Amino Acid Sequence↗

PubMed1995

Gene expression of vascular natriuretic peptide receptor in the aorta of hypertensive rats.

1. To elucidate the pathophysiologic role of vascular natriuretic peptide (NP) receptor in hypertension, we determined NP-A and NP-B receptor mRNA levels by means of ribonuclease protection assay in aorta of three types of hypertensive rats. 2. The NP-A receptor mRNA level was higher in stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) and deoxycorticosterone acetate-salt hypertensive rats than that in their respective control rats. On the contrary, the NP-A receptor mRNA level was lower in NG-nitro-L-arginine-methyl ester (L-NAME)-induced hypertensive rats compared with that in the control. 3. The NP-B receptor mRNA level did not show any significant change in all three hypertensive rats compared with their respective controls. 4. The present study suggests that high blood pressure is not the major factor regulating the NP receptor gene expression and also that the receptor subtype is independently regulated from each other.

Animals↗

PubMed1995

Perichondrial localization of ETA receptor in rat tracheal and xiphoid cartilage and in fetal rat epiphysis.

Autoradiographic studies using 125I-labeled endothelin-1 (ET-1) on sections of rat cartilage tissues, including the trachea, xiphisternum, and fetal rat epiphysis, revealed dense localization of endothelin receptors in the perichondrium. In contrast, the binding of ET-1 was not detected in the chondrocytes, cartilage matrix, and other connective tissues of the cartilage tissues tested. The perichondrial binding of 125I-ET-1 was completely abolished with BQ-123 [an endothelin receptor subtype A (ETA) antagonist] but not with BQ-3020 (an ETB agonist), and we demonstrated the perichondrial localization of ETA receptors. [3H]thymidine incorporation in vitro was significantly increased in rat xiphoid cartilage tissues exposed to ET-1. These findings suggest that the ET-1/ETA receptor system plays an important role in regulating cartilage metabolism and endochondral bone formation.

Animals↗

PubMed1995

Genetic differences of lipid metabolism in macrophages from C57BL/6J and C3H/HeN mice.

Cholesterol metabolism in macrophages from atherosclerosis-prone C57BL/6J mice was compared with that in macrophages from atherosclerosis-resistant C3H/HeN mice. Plasma total cholesterol levels of both types of mice were significantly increased, but HDL cholesterol level was increased only in C3H/HeN mice when a high-cholesterol diet (1% cholesterol) was fed for 5 weeks. After incubation of macrophages from male and female mice on the high-cholesterol diet with beta-VLDL for 24 hours, cholesterol content in macrophages from C57BL/6J was approximately 1.5- to 2.0-fold higher than in those from C3H/HeN mice. [3H]Cholesterol oleate-beta-VLDL incorporation into macrophages from C57BL/6J mice on the high-cholesterol diet was greater than incorporation into those from C3H/HeN mice. The release of [3H]cholesterol from macrophages from C57BL/6J mice on the high-cholesterol diet was one seventh that from macrophages from C57BL/6J mice on the basal diet or that from macrophages from C3H/HeN mice on the basal or high-cholesterol diet. Acid cholesterol esterase activity was almost the same in macrophages from any group. Acyl CoA:cholesterol acyltransferase activity in macrophages from C57BL/6J mice on the high-cholesterol diet increased compared with that from macrophages from C57BL/6J mice on the normal diet. Neutral cholesterol esterase activity in macrophages from C57BL/6J mice was about half of that in macrophages from C3H/HeN mice independent of the type of diet. There were no sex differences in these metabolisms. Considered with our previous data, these results suggested that a high-cholesterol diet may cause metabolic changes to accumulate cholesterol ester in macrophages from C57BL/6J mice in accordance with genetic abnormalities.

Animals↗