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Biomedical subjects

S Hirose

Publications and source records attributed to S Hirose.

At least 271 records · Page 15Linked to original sources
PubMed1995

Modulation of vascular natriuretic peptide receptor gene expression in hypertensive and obese hyperglycemic rats.

Receptors for natriuretic peptide (NP) consist of three subtypes: NP-A, NP-B, and NP-C. Recent studies in cultured aortic cells have suggested a phenotype-related switching of the vascular NP receptor from NP-A to NP-B. To ascertain the biological significance of the phenomenon in vivo, we developed a sensitive and reproducible ribonuclease protection assay and determined each receptor messenger RNA (mRNA) level in the vascular vessels of stroke-prone spontaneously hypertensive rats, deoxycorticosterone acetate-salt hypertensive rats, and genetically hyperglycemic. Wistar fatty rats and in cultured aortic smooth muscle cells. The aortic NP-A receptor mRNA level was significantly up-regulated in both types of hypertensive rats, whereas the NP-B receptor mRNA level did not show any significant change. Both NP-A and NP-B receptor mRNA levels were significantly up-regulated in Wistar fatty rats compared with the control values. There was no significant up-regulation of NP-A receptor mRNA in the inferior vena cava of the stroke-prone spontaneously hypertensive rats. Although the NP-A receptor was always the predominant subtype in rat aortic tissue, NP-B receptor was the predominant subtype in aortic smooth muscle cells in culture. These findings suggest that up-regulation of the NP-A receptor, but not the subtype switching, is the major modulation of receptor gene expression in both hypertensive and diabetic rats.

Animals↗
PubMed1995

Expression and localization of inducible nitric oxide synthase in anti-Thy-1 glomerulonephritis.

To elucidate a possible involvement of nitric oxide in the development of a mesangial proliferative glomerulonephritis induced by anti-Thy-1 antibody administration, glomerular expression of three isoforms of NO synthase (NOS), inducible NOS (iNOS), brain NOS, and endothelial NOS, was examined at both mRNA and protein levels by ribonuclease protection assay and immunofluorescence microscopy. Light microscopy showed an accumulation of polymorphonuclear leukocytes at 1 hour, lysis of mesangial cells at 1 day, a mesangial proliferative lesion at 4 to 10 days, and minimal residual glomerular lesions by 28 days. Ribonuclease protection assay showed that the glomerular expression of iNOS mRNA peaked at 1 hour and decreased thereafter. No substantial expression of iNOS mRNA was observed in normal glomeruli or in the nephritic glomeruli obtained at different time points (1, 4, 10, or 28 days). By immunofluorescence microscopy with a specific monoclonal antibody, an intense reaction for iNOS was demonstrated in a few cells in the glomeruli at 1 hour. Most of the iNOS-positive cells were identified as polymorphonuclear leukocytes. iNOS-positive cells were found less frequently in the glomeruli on days 1 and 4. Endothelial NOS mRNA was constitutively expressed in normal glomeruli and increased biphasically with two peaks at 1 hour and at 4 days or later; however, the peak expression was much less than that of iNOS mRNA at 1 hour. Expression of brain NOS mRNA was not detectable in either normal or nephritic glomeruli. These results show that iNOS is predominantly expressed in polymorphonuclear leukocytes accumulating at 1 hour in the glomeruli of anti-Thy-1 glomerulonephritis and suggest an involvement of NO in the initiation of the disease.

Animals↗
PubMed1995

Regulation of neutral cholesterol esterase activity by phospholipids containing negative charges in substrate liposome.

The effect of phospholipids on cholesteryl ester hydrolysis by neutral cholesterol esterase in alveolar macrophages was studied. Among the phospholipids used as emulsifiers, those with a negative charge, such as phosphatidylserine, phosphatidic acid, phosphatidylinositol, and cardiolipin, gave a higher level of hydrolysis by neutral cholesterol esterase than other less negatively charged phospholipids, such as phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, and sphingomyelin. Phospholipase D treatment of liposomes emulsified with phosphatidylcholine produced phosphatidic acid and enhanced cholesteryl ester hydrolysis. Phospholipase A2 treatment produced lysophosphatidylcholine and decreased the hydrolysis. The hydrolysis of cholesteryl ester in lipid droplets obtained from cholesterol-laden macrophages elicited by thioglycollate in the rat peritoneal cavity was low compared to artificial liposomes emulsified with phosphatidylcholine. The reason for this was speculated to be that lipid droplets were low in total phospholipids and poor in phospholipids with strong negative charges but rich in phosphatidylethanolamine and sphingomyelin. These results suggest that the polar heads of phospholipids may play an important role in cholesteryl ester hydrolysis by neutral cholesterolesterase.

Animals↗
PubMed1995

Participation of non-major histocompatibility antigen complex gene in experimental autoimmune uveitis.

It is known that the susceptibility to experimental autoimmune uveitis (EAU) is controlled by both major histocompatibility antigen complex (MHC) and non-MHC genes. In this report, we studied the role of non-MHC genes in the induction of EAU. LEW, WKAH, (LEW x WKAH)F1, and (LEW x WKAH)F2 rats were examined to determine the incidence and severity of EAU induced by immunization with bovine S-antigen (S-Ag). We found that all the LEW rats developed severe EAU within 2 weeks after immunization, but no WKAH rats did. Most of the F1 rats developed mild inflammation in 3-4 weeks after immunization. A quarter of the F2 rats developed EAU within 2 weeks, half of them, in 3-6 weeks after immunization, and the others did not. These findings suggest that only one non-MHC gene controls the susceptibility to S-Ag-induced EAU in rats.

Animals↗
PubMed1994

Angiotensin converting enzyme inhibitor but not calcium blocker down-regulates gene expression of vascular natriuretic peptide receptor in hypertensive rats.

We have recently found that vascular natriuretic peptide (NP)-A receptor mRNA is upregulated in genetically hypertensive (SHR-SP/Izm) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. In the present study, we examined the effects of antihypertensive treatments on aortic NP-A receptor mRNA expression in these hypertensive rats using ribonuclease protection assay. Oral administration of an angiotensin converting enzyme inhibitor, derapril, but not a calcium channel blocker, manidipine, produced a significant decrease of the NP-A receptor mRNA level after 4 weeks, while both antihypertensive agents showed similar hypotensive effects. Plasma renin was high in SHR-SP/Izm and low in DOCA-salt rats. These results suggest that the vascular renin-angiotensin system rather than the blood pressure has an important role in the regulation of the vascular NP-A receptor.

Animals↗
PubMed1994

Diploidy of Drosophila imaginal cells is maintained by a transcriptional repressor encoded by escargot.

The Drosophila escargot (esg) gene encodes a C2-H2-type zinc finger protein that is expressed in the imaginal discs and histoblasts. In some esg mutants, the abdominal histoblasts become polyploid. It has therefore been suggested that the role of esg is to maintain diploidy of the imaginal cells. We show that esg encodes a DNA-binding protein with high affinity for G/ACAGGTG, the consensus-binding sequence for the basic helix-loop-helix (bHLH) family of transcription factors (E2 box). This DNA-binding activity is essential for esg function in vivo as the strong embryonic lethal allele esgVS8 is caused by an amino acid change within the zinc finger region, leading to reduced affinity for DNA. In cultured cells, a heterodimer of the bHLH proteins Scute and Daughterless activates transcription from promoters containing E2 boxes. The esg protein strongly inhibits this activation, suggesting that esg may regulate developmental processes dependent on bHLH proteins. In larvae, esg protein expressed by the heat shock promoter can rescue the polyploid phenotype of abdominal histoblasts, demonstrating that the phenotype is attributable to a loss of esg function. esg must be expressed continuously during the larval period for efficient rescue. Ectopic expression of esg in the salivary glands inhibits endoreplication of DNA. These results suggest that esg is involved in transcriptional inhibition of genes required for endoreplication.

Animals↗
PubMed1994

Identification and characterization of IL-2 hyper-responsive NZB/WF1 CD5- B cells.

The responsiveness of CD5- and CD5+ B cells of BALB/c and NZB/WF1 mice to various cytokines was examined with respect to their growth and differentiation. BALB/c splenic CD5- B cells required longer incubation with IL-2 or pretreatment with IL-4 to respond to IL-2 by DNA synthesis, whereas NZB/WF1 CD5- B cells were highly competent to IL-2. Flow cytometric analysis demonstrated that NZB/WF1 and BALB/c CD5- B cells had higher and intermediate proportions of B cells positive for IL-2R beta, respectively. On the other hand, BALB/c and NZB/WF1 splenic CD5+ B cells consisted of lower proportion of B cells positive for IL-2R beta than did their corresponding CD5- B cells and grew meagerly in response to IL-2. Peritoneal exudative CD5+ B cells of NZB/WF1 mice lacked IL-2R beta mRNA expression and failed to respond to IL-2. Although both BALB/c and NZB/WF1 CD5- B cells pretreated with anti-IgM, IL-4, and IL-5 responded to IL-2 by DNA synthesis, only BALB/c CD5- B cells developed into IgM-producing cells. Furthermore, BALB/c, but not NZB/WF1 CD5-, B cells pretreated with anti-IgM and IL-5 responded to IL-2 by IgM production without DNA synthesis. Thus, cross-talk between IL-4 and IL-2 operated in the growth responses of both BALB/c and NZB/WF1 splenic CD5- B cells, whereas cross-talk between IL-5 and IL-2 operated only in the differentiation of BALB/c CD5- B cells, providing us with another intriguing functional abnormality of NZB/WF1 B cells.

Animals↗
PubMed1994

Cloning and expression of eel natriuretic-peptide receptor B and comparison with its mammalian counterparts.

A comparative study of the natriuretic-peptide receptor NPR-B was performed by cloning and expressing, in COS-1 cells, the NPR-B receptor subtype from the eel gill which exhibited a strong C-type-natriuretic-peptide (CNP)-induced guanylate cyclase activity. Like other mammalian NPR-B receptors, the eel NPR-B receptor consisted of a ligand-binding extracellular domain, a hydrophobic transmembrane domain, a kinase-like domain and a guanylate cyclase domain. Sequence comparison among the eel and mammalian receptors revealed a relatively low similarity (approximately 44%) in the extracellular domain compared to a very high similarity (approximately 84%) in the cytoplasmic regulatory and catalytic domains. This low similarity allowed identification of the amino acid residues or candidate regions important for the ligand-binding activity. RNase protection analysis of the eel NPR-B mRNA demonstrated that the message was predominantly expressed in the liver and atrium as well as in the gill with moderate-to-small amounts in the brain, ventricle, esophageal sphincter, stomach, posterior intestine and kidney. The high NPR-B mRNA levels in the liver, atrium and gill were found to decrease markedly when eels were transferred from fresh water to seawater and kept there for 2 weeks. Since similar changes are known to occur in the ligand CNP levels when eels are facing osmotic challenges, the CNP/NPR-B system appears to play an important role in their successful adaptation to salinity changes.

Amino Acid Sequence↗
PubMed1994

Impact of monocyte colony-stimulating factor upon beta-very low density lipoprotein (beta-VLDL) cholesterol metabolism in tetradecanoyl phorbol acetate-derived THP-1 cells.

The effect of monocyte colony stimulating factor (M-CSF) on the beta-very low density lipoprotein (beta-VLDL) metabolism in THP-1 cells (human leukemia cell line) was studied. THP-1 cells treated with M-CSF decreased Latex Bead phagocytosis, but the cells incubated with 12-tetradecanoyl-phorbol-13-acetate (TPA) enhanced phagocytosis 2.5-fold. Binding activity of 125I-M-CSF to THP-1 cells was higher than that in THP-1 cells elicited with TPA. THP-1 cells incubated with M-CSF before TPA treatment were designated MT macrophages, and those incubated with M-CSF after TPA treatment were called TM macrophages. When these cells were incubated with beta-VLDL, the cholesterol ester content in MT macrophages was less than in TM macrophages. The uptake of [3H]cholesterol oleate-beta-VLDL in MT macrophages was the same as in TM macrophages. The released radioactivity from [3H]cholesterol oleate-beta-VLDL loaded MT macrophages was higher than that from TM macrophages. Acid cholesterol esterase activity and ACAT activity were the same in both types of macrophages. Neutral cholesterol esterase activity was higher in MT than in TM macrophages. These results suggested that beta-VLDL-induced cholesterol ester deposition in THP-1 cells-derived macrophages was suppressed by M-CSF, when M-CSF acted at the stage of monocytes (THP-1 cells), and that the reduction of cholesterol ester might be due to enhanced release of cholesterol from the cells with high neutral cholesterol esterase activity.

Cell Line↗
PubMed1994

Autocrine regulation of rat chondrocyte proliferation by natriuretic peptide C and its receptor, natriuretic peptide receptor-B.

Natriuretic peptide receptor-B (NPR-B) was identified in rat chondrocytes, and its physiological functions were investigated. Rat tissues, including the xiphoid cartilage, brain, lung, liver, adrenal gland, and kidney, were screened for NPR-B activity, which we assayed by receptor guanylate cyclase activity specifically stimulated by C-type natriuretic peptide (CNP), a known selective activator of NPR-B. Cartilage showed distinctly higher NPR-B activity. Furthermore, exposure of cultured rat chondrocytes to CNP (10(-6) M) resulted in a large increase in intracellular cGMP production (376 +/- 38 pmol/well), with threshold responses occurring between 10(-10) and 10(-9) M CNP. Atrial natriuretic peptide and brain natriuretic peptide also stimulated cGMP production in rat chondrocytes but with a potency that was at least 10 times less than that of CNP. Polymerase chain reaction analysis also demonstrated NPR-B gene expression in adult rat xiphisternum and cultured chondrocytes. These findings indicate that NPR-B is present in rat chondrocytes. In rat chondrocytes exposed to CNP, [3H]thymidine incorporation was inhibited in a dose-dependent manner (half-maximal response, 10(-11)M). However, much higher concentrations of atrial natriuretic peptide were required to induce the inhibition of thymidine incorporation. Interestingly, CNP-like immunoreactivity was detected in the conditioned medium from chondrocyte cultures. In addition, TGF-beta 1, a multifunctional cytokine, induced a marked increase in CNP secretion and CNP mRNA levels in chondrocytes. These results indicate that autocrine CNP inhibits mitogenesis in chondrocytes via NPR-B under the control of TGF-beta 1.

Animals↗
PubMed1994

Cloning, amino acid sequence and tissue distribution of porcine thimet oligopeptidase. A comparison with soluble angiotensin-binding protein.

We have previously determined the amino acid sequence of porcine soluble angiotensin-binding protein (sABP) by cDNA cloning and sequencing. In this study, we have cloned a sABP homologue (PABH) from the same porcine cDNA libraries used for sABP cloning. PABH and sABP have 65% sequence identity. Sequence comparisons with other proteins revealed very high similarities between porcine PABH and rat thimet oligopeptidase (90%), and between porcine sABP and rabbit microsomal endopeptidase (93%). This suggests that PABH and thimet oligopeptidase are identical and that sABP and microsomal endopeptidase are also the same. Indeed, sABP was shown to have a peptidase activity that is sensitive to the metal-chelating agents EDTA and 1,10-phenanthroline; sABP was also sensitive to the thiol reagent p-chloromercuriphenylsulfonic acid. RNase-protection assays, using RNA preparations from various porcine tissues, indicated that thimet oligopeptidase mRNA is ubiquitously expressed whereas sABP mRNA is predominantly expressed in the liver, kidney and adrenal gland. This assay also revealed tissue-specific alternative splicing of the sABP-encoding message.

Amino Acid Sequence↗
PubMed1994

Mutational analysis of disulfide bridges in the type C atrial natriuretic peptide receptor.

The type C receptor (ANP-C or NPR-C) for the natriuretic peptides was demonstrated, by site-directed mutagenesis, to have an immunoglobulin-like disulfide bonding pattern that is very similar to that of the cytokine receptor superfamily. The mature form of ANP-C has a disulfide-linked homodimeric structure and contains 5 conserved cysteine residues per subunit, all in the extracellular domain. To identify the cysteine residue involved in the dimerization and further to determine the intramolecular disulfide bridges and their functional roles, cysteine to serine mutations of the 5 cysteine residues were constructed. An analysis of the mutant receptors expressed in COS-1 cells by 125I-ANP binding assay and by measuring difference in their electrophoretic mobilities on sodium dodecyl sulfate-polyacrylamide gels indicated that 1) the first 4 cysteine residues are joined sequentially, forming the Cys104-Cys132 and Cys209-Cys257 loops of 29 and 49 residues, respectively; 2) the two disulfide-linked loops are essential for the ligand binding activity; 3) the 5th cysteine residue Cys469 is used in the formation of covalently linked dimers; and 4) the covalent association of the subunit through the disulfide bond involving Cys469 has no apparent influence on ligand-receptor interactions. The intramolecular disulfide bond Cys104-Cys132 was also confirmed by direct protein sequencing of tryptic fragments of purified ANP-C receptor. The secondary structural features revealed here will be useful in understanding the structure and function relationships of not only the dimeric ANP-C receptor, which has only a short cytoplasmic tail, but also the ANP-A (GC-A) and ANP-B (GC-B) receptor subtypes, which have a guanylate cyclase domain in their long cytoplasmic tail and have recently been shown to possess an oligomeric structure, since they have similarly spaced cysteine residues in their extracellular domains.

Amino Acid Sequence↗
PubMed1994

Glycoinositol phospholipid anchor-defective K562 mutants with biochemical lesions distinct from those in Thy-1- murine lymphoma mutants.

Deficient expression of glycoinositol phospholipid (GPI)-anchored surface proteins has been linked to six different genetic defects in Thy-1- murine lymphoma mutants. In this study, human K562 cell mutants defective in GPI anchoring were derived by anti-decay-accelerating factor (CD55) based negative fluorescent cell sorting of N-methyl-N'-nitro-N-nitrosoguanidine pretreated cells. Homologous cell fusions of six clones that complemented a previously described K562 mutant corresponding to one of the Thy-1- mutant classes (Hirose, S., Mohney, R. P., Mutka, S. C., Ravi, L., Singleton, D. R., Perry, G., Tartakoff, A., and Medof, M. E. (1992) J. Biol. Chem. 267, 5272-5278) showed that they segregated into two complementation groups. In heterologous cell fusions, representative clones of each group complemented Thy-1 expression by all of the previously described GPI anchor pathway-defective Thy-1- murine lymphoma classes (A, B, C, E, F, and H) but not class(es) D (and I) defective in the Thy-1 structural gene. Analyses of putative GPI anchor precursors synthesized by the two lines revealed that one mutant exhibited a complete block in deacetylation of N-acetyl-D-glucosamine-inositol phospholipid to glucosamine (GlcN)-inositol phospholipid, whereas the other mutant assembled GlcN-inositol phospholipid and subsequent mannose (Man)-containing intermediates but showed markedly increased amounts of the terminal ethanolamine (EthN)-phosphate (P)-substituted putative anchor precursors, EthN-P-6ManMan(EthN-P-->)ManGlcN- and EthN-P-6Man(EthN-P-6)Man(EthN- P-->)ManGlcN-acylinositol phospholipid (H7 and H8). We designate these new complementation classes J, harboring a defect in N-acetyl-D-glucosamine-inositol phospholipid deacetylation, and K, deficient in a step preliminary to or associated with protein transfer of assembled anchor precursors. The availability of these new mutant classes should aid in characterization of the GPI anchor pathway enzymes providing for these reactions.

Animals↗
PubMed1994

Suppression of IgE production in unseparated spleen cell cultures.

When B cells from BALB/c mice were cultured with lipopolysaccharide (LPS) and interleukin-4 (IL-4), a large amount of IgE was detected in the culture supernatants. The IgE production from unseparated spleen cells cultured with LPS and IL-4 was less than the amount of IgE obtained from separated B cells. When syngeneic T cells were added to separated B cells cultures, which were subsequently stimulated with LPS and IL-4, less IgE was produced, as compared to cultures without T cells. The hypothesis that T cells, or factors secreted by these cells, inhibit IgE production is supported by the fact that the degree of suppression of IgE production paralleled the number of T cells added. CD8(+)-enriched T cells were slightly more suppressive than CD4(+)-enriched T cells. Addition of exogenous IL-3 was only partially suppressive. These observations suggest that IL-4 added to unseparated spleen cells in vitro stimulates B cells for IgE production and also stimulates T cells. Lymphokines secreted by these stimulated T cells may in turn act on B cells. Some of these lymphokines, such as interferon-gamma and IL-2, may have a suppressive action on IgE production.

Animals↗