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Y Ninomiya

Publications and source records attributed to Y Ninomiya.

At least 163 records · Page 9Linked to original sources
PubMed1996

Salt taste responses of mouse chorda tympani neurons: evidence for existence of two different amiloride-sensitive receptor components for NaCl with different temperature dependencies.

1. Inhibitory effects of amiloride on salt responses of single fibers of the chorda tympani nerve of the C57BL/6 strain of mice were examined at two different temperatures (approximately 12 and 24 degrees C). 2. Of 36 single fibers that responded to NaCl, 20 fibers showed strong suppression of responses to NaCl actuated by lingual treatment with amiloride (amiloride-sensitive fibers), whereas the remaining 16 fibers showed no such amiloride inhibition (amiloride-insensitive fibers). 3. Twenty amiloride-sensitive fibers were further classified into two subgroups according to the temperature dependency of their NaCl responses. In 15 of 20 fibers, amiloride-inhibitable NaCl responses were larger at 24 degrees C than at 12 degrees C, whereas the reverse was true for the remaining 5 fibers. All amiloride-insensitive fibers showed smaller responses to NaCl at 12 degrees C. 4. These results suggest that there exist two different amiloride-sensitive receptor components for NaCl with different temperature dependencies in mouse taste cells: one is more sensitive to NaCl at the higher temperature, and the other is more sensitive at the lower temperature.

Amiloride↗
PubMed1996

Role of extracellular matrix in experimental vasospasm. Inhibitory effect of antisense oligonucleotide on collagen induction.

BACKGROUND AND PURPOSE: Although it has been suggested that collagen plays a role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage, there has been no constructive research to prove it directly. In this study we stopped the transcription of the procollagen type I gene by introducing antisense oligonucleotides for its mRNA in a rat femoral artery model of vasospasm induced by blood and assayed the changes in the vasoconstrictive activity of the vessel and expression of the procollagen mRNA. METHODS: We applied antisense, sense, or missense oligonucleotides, located at the carboxyl propeptide region for alpha 1(I) procollagen mRNA, onto the femoral artery in a rat femoral artery model of vasospasm. The diameter of the artery was measured by angiography. The transcription level of the procollagen gene in the arterial tissue was assayed by use of reverse transcription-polymerase chain reaction. Morphological change in the artery was observed with aldehyde-fuchsin-Masson-Goldner staining. RESULTS: In the model, when the artery was exposed to antisense oligonucleotides in pluronic gel for 5 days to prevent arterial contraction, the contraction was inhibited at a significant level (76.0% +/- 5.6) when compared with that in control experiments using sense oligonucleotides (64.0% +/- 2.4), missense oligonucleotides (63.5% +/- 3.5), or gel alone (62.1% +/- 5.8). The application of antisense oligonucleotide resulted in a marked decrease in alpha 1(I) procollagen mRNA expression as determined by polymerase chain reaction, indicating that the collagen reduction by antisense oligonucleotides occurred at the transcription level. Histological staining suggested that collagen accumulation at the site in the artery where antisense oligonucleotide had been administered was indeed less than that in the control artery. CONCLUSIONS: The results indicate that the induction of procollagen type 1 could cause pathogenesis of the arterial contraction induced by blood in a rat femoral vasospasm model.

Animals↗
PubMed1996

Basement membrane abnormalities in human eyes with diabetic retinopathy.

Vascular and parenchymal basement membranes (BMs) are thickened in diabetes, but alterations in individual BM components in diabetic eyes, especially in diabetic retinopathy (DR), are obscure. To identify abnormalities in the distribution of specific constituents, we analyzed cryostat sections of human eyes obtained at autopsy (seven normal, five diabetic without DR, and 13 diabetic with DR) by immunofluorescence with antibodies to 30 BM and extracellular matrix components. In non-DR eyes, no qualitative changes of ocular BM components were seen. In some DR corneas, epithelial BM was stained discontinuously for laminin-1, entactin/nidogen, and alpha3-alpha4 Type IV collagen, in contrast to non-DR corneas. Major BM alterations were found in DR retinas compared to normals and non-DR diabetics. The inner limiting membrane (retinal BM) of DR eyes had accumulations of fibronectin (including cellular) and Types I, III, IV (alpha1-alpha2), and V collagen. The BM zone of new retinal blood vessels in neovascularized areas accumulated tenascin and Type XII collagen, whereas normal, diabetic, and adjacent DR retinas showed only weak and irregular staining. In preretinal membranes, perlecan, bamacan, and Types VI, VIII, XII, and XIV collagen were newly identified. Diabetic BM thickening appears to involve qualitative alterations of specific BM markers at an advanced disease stage, with the appearance of DR.

Basement Membrane↗
PubMed1996

Steroid hormone-induced expression of the chicken ovalbumin gene and the levels of nuclear steroid hormone receptors in chick oviduct.

The induction of the chicken ovalbumin (OVA) gene by different classes of steroid hormones and the mRNA levels of estrogen (ER), progesterone (PR), and glucocorticoid (GR) receptors were studied in chick oviducts. Combined treatment with two hormones increased the induction of the OVA gene more than single treatment, when the levels of OVA mRNA were measured with Slot blot analysis. To discover the role of nuclear steroid hormone receptors as transcriptional factors in the OVA gene induction, we analyzed the levels of ER (with RT-PCR), PR, and GR mRNAs (with Northern blotting). The level of PR mRNA was increased only by estrogen, while no steroid hormone affected the levels of ER and GR mRNAs. Thus, these findings show that the levels of nuclear receptors do not reflect the OVA mRNA level in the oviduct of steroid hormone-treated chicks.

Animals↗
PubMed1996

Vitamin A is involved in estrogen-induced cell proliferation but not in cytodifferentiation of the chicken oviduct.

We examined vitamin A-deficient chicks to determine whether vitamin A affects the estrogen-induced development of the chick oviduct. When oviduct development was stimulated for 5 days with the synthetic estrogen, diethylstilbestrol, the wet weight of the oviduct in vitamin A-deficient chicks was only half that in control chicks. The DNA content in this tissue showed that the decreased oviduct weight in the vitamin A-deficient chicks was caused by the decreased proliferation of oviduct cells. However, the estrogen-induced expression of the ovalbumin gene was not affected by the vitamin A deficiency, suggesting that estrogen-induced cytodifferentiation is not affected by vitamin A. To clarify the vitamin A action on estrogen-induced development in the oviduct, transcripts of nuclear estrogen receptor (ER) and all-trans-retinoic acid (RAR alpha, beta and gamma) receptors, which exert the effects of estrogen and vitamin A, were measured. The ER, RAR alpha and RAR beta genes, but not that of RAR gamma, were expressed during oviduct development, indicating that estrogen and vitamin A may control the expression of target genes through their cognate receptors. Thus, we have shown that vitamin A is involved in estrogen-induced cell proliferation but not in cytodifferentiation of the chicken oviduct.

Animals↗
PubMed1996

Inhibition of vascular contraction by intracisternal administration of preproendothelin-1 mRNA antisense oligoDNA in a rat experimental vasospasm model.

To clarify the role of endothelin-1 (ET-1) in the etiology of hemolysate-induced contraction of vessels, the authors introduced antisense oligoDNA for preproendothelin-1 (ppET-1) messenger RNA in a rat model of vasospasm. Phosphorothioate antisense oligoDNAs for ppET-1 were injected into the cisterna magna. Fluorescein isothiocyanate-labeled phosphorothioate antisense oligoDNAs were proven by fluorescence chasing to be incorporated into the vascular wall. Striking inhibitory effects of experimental vasospasm were observed in the basilar artery (BA) in which the oligoDNAs were injected. The vascular contraction was significantly inhibited by oligoDNAs after 20 minutes of hemolysate exposure, which suggested that ET synthesis started approximately 20 minutes after hemolysate stimulation. Expression of ppET-1 in the BA in which the spasm was inhibited was markedly suppressed at the transcription level. The results indicate that ET-1 may play an important role in hemolysate-induced vasoconstriction in rats. In addition, the antisense approach in the cerebrospinal fluid might be a useful tool for preventing cerebral vasospasm.

Animals↗
PubMed1996

Posttranslational regulation of type I collagen in corneal endothelial cells.

PURPOSE: Type I collagen synthesis in corneal endothelial cells does not correlate with steady state collagen RNA levels; although substantial amounts of alpha 2(I) collagen RNA are present in these cells, type I collagen is not detected. This allowed the authors to investigate the possibility of posttranscriptional control of type I collagen in corneal endothelial cells. METHODS: The alpha 2(I) collagen RNA structures of normal and modulated corneal endothelial cells were analyzed by S1 nuclease protection analysis, whereas the nucleotide sequences were obtained by rapid amplification of cDNA ends technique. In situ hybridization of type I collagen was demonstrated with immunofluorescence; synthesis and degradation of the molecule were analyzed by pulse-chase experiments and then by immunoprecipitation with antiprocollagen I antibody. RESULTS: The cDNA covering the 5'-untranslated region (UTR) of alpha 2(I) collagen RNA obtained from normal corneal endothelial cells and from modulated corneal endothelial cells that predominantly produce type I collagen demonstrate identical sequences in their 5' untranslated and coding sequences. In both mRNA, the length of the 5'-untranslated segment is 127 nucleotides. There were also two AUG codons; the second AUG codon, which is 17 nucleotides upstream from the translation initiation codon, is conserved, as observed in human and chicken alpha 2(I) mRNA. When the sequence covering the 3'-UTR of corneal endothelial alpha 2(I) mRNA was compared with that of alpha 2(I) mRNA obtained from the modulated cells, there were differences in only two nucleotides. The length of the 3'-untranslated segment of each mRNA is 297 nucleotides up to the consensus polyadenylation recognition site (AAUAAAAUAAA), which both cells use. Immunofluorescent staining of corneal tissue in vivo demonstrated that the corneal endothelium stains with anti-type I collagen antibodies, but there is no staining in the underlying Descemet's membrane. In pulse-chase experiments, the newly synthesized type I procollagen, composed of pro alpha 1(I) and pro alpha 2(I) chains as determined by V8 protease peptide mapping, reached the highest intracellular level at 45 minutes, after which its detection decreased. Cells chased for 120 minutes demonstrated no trace of type I procollagen in the cell layer; medium fractions showed no detectable type I procollagen during the entire 120-minute chase. CONCLUSIONS: These results suggest that type I collagen is synthesized in corneal endothelial cells and that such undesired expression is regulated at the posttranslational level, perhaps by intracellular degradation.

Amino Acid Sequence↗
PubMed1996

Extracellular matrix alterations in human corneas with bullous keratopathy.

PURPOSE: To uncover abnormalities of extracellular matrix (ECM) distribution in human corneas with pseudophakic and aphakic bullous keratopathy (PBK/ABK). METHODS: Indirect immunofluorescence with antibodies to 27 ECM components was used on frozen sections of 14 normal and 20 PBK/ABK corneas. RESULTS: Fibrillar deposits of an antiadhesive glycoprotein tenascin in the anterior and posterior stroma, epithelial basement membrane (BM), bullae and subepithelial fibrosis (SEF) areas, and posterior collagenous layer (PCL) were revealed in disease corneas. Tenascin in midstroma, which was observed in some cases, correlated with decreased visual acuity. In normal central corneas, tenascin was never found. Other major ECM abnormalities in PBK/ABK corneas compared to normals included: discontinuous epithelial BM straining for laminin-1 (alpha 1 beta 1 gamma 1), entactin/nidogen and fibronectin; accumulation of fibronectin and alpha 1-alpha 2 type IV collagen on the endothelial face of the Descemet's membrane; and abnormal deposition of stromal ECM (tenascin, fibronectin, decorin, types I, III, V, VI, VIII, XII, XIV collagen) and BM components (type IV, collagen, perlecan, bamacan, laminin-1, entactin-nidogen, fibronectin) in SEF areas and in PCL. CONCLUSIONS: The study provides a molecular description of an ongoing fibrosis on the epithelial, stomal, and endothelial levels in PBK/ABK corneas. These fibrotic changes may follow initial endothelial damage after cataract surgery, may be caused by the upregulation of fibrogenic cytokines, and may play a significant role in the progression of bullous keratopathy.

Aged↗
PubMed1996

[Visual functional changes in idiopathic macular holes treated by vitrectomy].

We evaluated visual functional measurements, visual acuity, central retinal sensitivity in a Humphrey field analyzer, and binocular function in Stereotest, Amsler grid testing, of 51 idiopathic macular holes before and after vitrectomy. In 36 of 51 eyes (71%) where the macular hole was closed after vitrectomy, there were improvements in all visual functional measurements postoperatively. The eyes in which the macular hole was closed had significantly better visual acuity before vitrectomy than those in which the hole was not closed. In 16 of 51 eyes that had visual acuity of less than 20/200 preoperatively, central retinal sensitivity before vitrectomy was higher in the eyes where the macular hole was closed than in those in which it was not closed. These measurements are useful for evaluation of visual functional improvements after vitrectomy and can help to choose candidates for macular hole surgery.

Adult↗
PubMed1996

Regulation of interleukin-2 receptor gamma chain mRNA expression in human monocytic cell line THP-1.

The interleukin-2 receptor (IL-2R) gamma chain (gamma c chain) is shared by IL-4R, IL-7R, IL-9R, and IL-15R and plays an important role in regulation of the immune system. However, its regulation in monocytic cell lines has not been well clarified. We examined the expression and regulation of the IL-2R alpha, IL-2R beta, gamma c chain, IL-4R and IL-7R mRNA in a human monoblastic leukemia cell line, THP-1. Unstimulated THP-1 cells constitutively expressed a low level of gamma c chain and IL-4R mRNA. Phorbol myristate acetate (PMA) induced macrophage-like differentiation and up-regulated the gamma c chain mRNA expression in THP-1 cells. This effect of PMA was suppressed by the protein kinase inhibitors H-7 and staurosporine. PMA did not affect the expression of the other IL-R mRNAs examined. 1 alpha, 25(OH)2D3 and interferon-gamma also induced differentiation of THP-1 cells, but these reagents did not affect the expression of the IL-R mRNAs in THP-1 cells. These findings suggest that the expression of the gamma c chain mRNA is regulated by the PMA-dependent pathway and is not associated with that of the other IL-R mRNAs.

Calcitriol↗
PubMed1995

Association of minisatellite instability with c-myc amplification and K-ras mutation in methylcholanthrene-induced mouse sarcomas.

Instability of microsatellite sequences are frequently found in human tumors. In addition, minisatellite sequences, another group of highly unstable sequences, serve as sensitive markers of genetic instability. We have studied minisatellite instability in methylcholanthrene-induced mouse sarcomas. These sarcomas frequently carry the amplified c-myc gene. Seven sarcomas without the amplification and seven others with the amplification were selected randomly. Regardless of the state of the c-myc gene amplification, these sarcomas exhibited a varying degree of transplantability in syngeneic mice. The hypervariable mouse minisatellite locus Ms6hm was found to be highly unstable, specifically among sarcomas with the amplified c-myc gene. However, chromosome instability, as analyzed by micronucleus assay, was observed similarly for two groups of sarcomas. In addition, transversion of G to C and A to T was detected at the K-ras gene in four of the seven sarcomas with the amplified c-myc gene, and these mutations are thought to be induced directly by methylcholanthrene. Thus, concomitant occurrence was observed for three seemingly unrelated mutations, amplification of the c-myc locus, point mutation of the K-ras gene, and instability at the hypervariable mouse minisatellite locus. The present study indicates a possible involvement of K-ras mutation and c-myc amplification in induction of genetic instability in methylcholanthrene-induced mouse sarcomas.

Animals↗
PubMed1995

Isolation and structure of the COL4A6 gene encoding the human alpha 6(IV) collagen chain and comparison with other type IV collagen genes.

The genes COL4A5 and COL4A6, coding for the basement membrane collagen chains, alpha 5(IV) and alpha 6(IV), respectively, are located head-to-head in close proximity on human chromosome Xq22, and COL4A6 is transcribed from two alternative promoters in a tissue-specific fashion (Sugimoto M., Oohashi T., and Ninomiya Y. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 11679-11683). Immunofluorescence studies using alpha chain-specific antibodies demonstrated that the two genes are expressed in a tissue-specific manner (Ninomiya, Y., Kagawa, M., Iyama, K., Naito, L., Kishiro, Y., Seyer, J. M., Sugimoto, M., Oohashi, T., and Sado, Y. (1995) J. Cell Biol. 130, 1219-1229). We report here for the first time the isolation and the structural organization of the human COL4A6 gene. The entire gene presumably exceeds 200 kilobase pairs and contains 46 exons. Exons 1' and 1 encode the two different 5'-UTRs and the two amino-terminal parts of of the signal peptide. The carboxyl part of the signal peptide and the 7 S domain are coded for by the following 6 different exons, 2-7, whereas the exons 7-42 encode the central COL 1 domain, which contains the Gly-X-Y repeats. The last three exons, 43-45, encode the carboxyl-terminal NC1 domain. Sizes of more than a half of the exons of the gene are the same as those of Col4a2 but quite different from those of COL4A5. Within the COL4A6 gene we found three CA repeat markers that can be used for allele detection. The detailed structure of the COL4A6 gene and the high heterozygosity microsatellite markers located within the gene will be useful for linkage analysis and familial diagnosis of diseases caused by mutations of this gene.

Amino Acid Sequence↗
PubMed1995

Coding sequence and alternative splicing of the mouse alpha 1(XI) collagen gene (Col11a1).

Several overlapping cDNA clones corresponding to the entire coding sequence of the mouse alpha 1(XI) collagen gene (Col11 a1) were isolated. The conceptual amino acid translation indicated a high degree of sequence identity (93%) with the human alpha 1(XI) chain. The cloning experiments also revealed alternative splicing of the sequence coding for 85 residues located within the acidic region of the amino-globular domain of alpha 1(XI). Analysis of RNA samples from different embryonic tissues suggested that alternative splicing might be confined to tissue destined to become bone.

Amino Acid Sequence↗
PubMed1995

A fibrillar collagen gene, Col11a1, is essential for skeletal morphogenesis.

Mice that are homozygous for the autosomal recessive chondrodysplasia (cho) mutation die at birth with abnormalities in cartilage of limbs, ribs, mandible, and trachea. Limb bones of newborn cho/cho mice are wider at the metaphyses than normal bones and only about half the normal length. By linkage analysis, the cho gene and the gene encoding the alpha 1 (XI) chain of cartilage collagen XI were mapped to the same region of chromosome 3. Deletion of a cytidine residue about 570 nt downstream of the translation initiation codon in cho alpha 1 (XI) mRNA causes a reading frame shift and introduces a premature stop codon. The data demonstrate that collagen XI is essential for normal formation of cartilage collagen fibrils and the cohesive properties of cartilage. The results also suggest that the normal differentiation and spatial organization of growth plate chondrocytes is critially dependent on the presence of type XI collagen in cartilage extracellular matrix.

Amino Acid Sequence↗
PubMed1995

Structural and functional analysis of the promoter of the human alpha 1(XI) collagen gene.

In order to eventually elucidate the mechanisms regulating alpha 1(XI) collagen expression in cartilaginous and non-cartilaginous tissues, we performed an initial analysis of the structural-functional features of the promoter of the human gene (COL11A1). After cloning and sequencing the 5' portion of COL11A1, primer extension and nuclease protection assays identified several minor transcriptional start sites clustered around a major one located 318 base pairs from the ATG codon. Consistent with this finding, analysis of the upstream sequence revealed the absence of a TATA motif and the presence of several GC boxes. Transient transfection experiments delineated the smallest promoter sequence directing relatively high expression of a reporter gene in a cell type-specific manner. Nine nuclear protein-bound areas were located within this promoter sequence of the COL11A1 gene. Sequence homologies suggested that the majority of the footprints correspond to potential binding sites for ubiquitous nuclear proteins, such as AP2 and Sp1. Additional experimental evidence indicated that one of the protected areas may bind a transcriptional complex that is identical or closely related to the one that regulates tissue specificity in the coordinately expressed alpha 2(V) collagen gene.

Animals↗
PubMed1995

Developmental defects of the ventromedial hypothalamic nucleus and pituitary gonadotroph in the Ftz-F1 disrupted mice.

Ad4BP (or SF-1) has been identified as a transcription factor which regulates all the steroidogenic P450 genes in the peripheral organs, and is encoded by the mammalian homologue of Drosophila FTZ-F1 gene. mRNA coding for Ad4BP was detected in the hypothalamus and pituitary of rats by RT-PCR. Immunohistochemical analyses using an antiserum to Ad4BP in the brain and pituitary revealed that the transcription factor is expressed in nuclei of the dorsomedial part of the ventromedial hypothalamus (dmVMH) and in some subpopulation of the adenohypophysial cells. Double immunostaining of the pituitary for Ad4BP and trophic peptide hormones, FSH, TSH, and ACTH, indicated a restricted localization of Ad4BP to the gonadotroph. Disruption of the mouse Ftz-F1 gene was clarified to induce severe defects in the organization of the dmVMH and the function of the pituitary gonadotroph. However, some of the dm VMH neurons and pituitary gonadotrophs persisted, which provided a sharp contrast to complete agenesis of the peripheral steroidogenic tissues (adrenal and gonads) in the mutant mouse. Additional abnormalities were seen in the ventrolateral part of VMH and dorsomedial hypothalamic nucleus, both of which do not express Ad4BP but have strong reciprocal fiber-connections with the dmVMH. Aromatase P450-containing cells in the medial preoptico-amygdaloid region, which were devoid of Ad4BP, persisted even in the brain of the gene disrupted mice. The present results clearly showed that the hypothalamic and pituitary Ad4BPs are essential to normal development of the functional VMH and gonadotroph through some mechanism distinct from that in the peripheral steroidogenic tissues.

Animals↗
PubMed1995

Developmental pattern of expression of the mouse alpha 1 (XI) collagen gene (Col11a1).

Fibrillar networks are intimately involved in several morphogenetic processes which underlie the harmonious development of the vertebrate embryo. Recent genetic evidence has demonstrated that the minor types V and XI collagen are key regulators of types I and II fibrillogenesis in non-cartilaginous and cartilaginous matrices, respectively. A comprehensive understanding of the expression and regulation of the genes coding for the chains of the minor collagen types is therefore relevant to animal morphogenesis and development. The present study was undertaken to elucidate the embryonic pattern of expression of the gene coding for the mouse alpha 1 chain of type XI colagen (Col11a1) using the technique of in situ hybridization. Transcripts of the Col11a1 gene were detected as early as 11 days of gestation. The alpha 1(XI) transcripts were found to accumulate mostly in cartilaginous tissues, such as the chondrocranium and the developing limbs. Like the major cartilage-specific collagen (type II), Col11a1 expression was also noted in the neuro-epithelium of the brain. However, alpha 1(XI) transcripts accumulated in several other non-cartilaginous sites. They include odontoblasts, trabecular bones, atrioventricular valve of the heart, the tongue, the intestine, and the otic vesicle. Altogether, the data confirm that Col11a1 has a broader spectrum of expression than previously thought. This finding raises the possibility that the alpha 1(XI) chain may participate in the formation of stage- and tissue-specific trimers with distinct functional properties.

Animals↗