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Biomedical subjects

Y Tashiro

Publications and source records attributed to Y Tashiro.

At least 91 records · Page 5Linked to original sources
PubMed1994

Immunocytochemical analyses of distributions of Na, K-ATPase and GLUT1, insulin and transferrin receptors in the developing retinal pigment epithelial cells.

The retinal pigment epithelium (RPE) is unique in that Na,K-ATPase is predominantly localized on its apical surface. We studied the distributions of Na,K-ATPase and glucose transporter GLUT1, insulin and transferrin receptors in developing rat RPE cells immunocytochemically. Na,K-ATPase, first detected in 17-day-old embryonic eyes, was already distributed predominantly on the apical surface. This reversed distribution of Na,K-ATPase was maintained throughout their life. Insulin receptor and transferrin receptor were distributed exclusively on the basolateral surface. By quantitative immunogold electron microscopic technique we found that glucose transporter GLUT1 is distributed almost equal in amount on both the apical and basolateral surfaces of RPE cells, thus presumably constructing an efficient pathway for glucose transport from the choriocapillaries to the neural retina through the blood-retinal barrier. These results suggest that in the RPE cells the intrinsic basolateral plasma membrane proteins are sorted out at least in three different ways.

Animals↗
PubMed1994

Sodium pump distribution is not reversed in the DBA/2FG-pcy, polycystic kidney disease model mouse.

Recently, it has been reported that Na,K-ATPase in the renal epithelia of human autosomal dominant polycystic kidney disease and cpk mouse, a murine model of autosomal recessive polycystic kidney disease, mislocates to apical plasma membrane and that mislocated Na,K-ATPase causes the cyst formation. Whether the DBA/2FG-pcy mice, which are presumably a suitable model for autosomal dominant polycystic kidney disease, also exhibit the reversal polarity of Na,K-ATPase localization was examined. Kidneys of newborn DBA/2FG-pcy mice, and those at early and late stages of cyst development were examined by immunohistochemical techniques. At any stage, abnormal distribution of Na,K-ATPase on the apical membranes of tubular epithelial cells could not be detected. It is suggested that cysts can be formed without reversed polarity of Na,K-ATPase distribution in pcy mice.

Animals↗
PubMed1994

[Multicentric Castleman's disease accompanied with both lymphoid interstitial pneumonia and interstitial nephritis].

A 60-year old man admitted in November, 1991 because of hyperproteinemia. He had shown a gradual increase in serum levels of gamma-globulin since 1981, and idiopathic plasmacytic lymphadenopathy with hyperimmunoglobulinemia was diagnosed in 1989 when he was admitted to another hospital because of persistent swelling of bilateral inguinal lymph nodes since 1986. Multiple swelling of lymph nodes was observed in the right supraclavicle fossa, the left axillary and bilateral inguinal region, and diffuse reticulo-nodular shadows were observed on his chest roentogenogram. Other laboratory findings were as follows; erythrocyte sedimentation rate 143 mm/hr, CRP 3+, Hb 9.4 g/dl, TP 13.7 g/dl with 69.4% of beta-gamma bridge, BUN 21.1 mg/dl, creatinine 1.6 mg/dl, PaO2 77.6 mmHg, plasma cell count in bone marrow 6.4% and positive tests for autoantibodies such as rheumatoid factor, anti-DNA antibody, anti-smooth muscle antibody, and direct Coombs test. Serum interleukin-6 (IL-6) level increased to 259 pg/ml and IL-1 beta was 39.1 pg/ml. Specimens of both transbronchial lung biopsy and fine-needle kidney biopsy revealed a marked infiltration of lymphocytes and plasma cells into interstitial regions of lung and kidney. We reported here a case of multicentric Castleman's disease (MCD) who also demonstrated lymphoid interstitial pneumonia and interstitial nephritis. The present study suggests that some cytokines including IL-6 and IL-1 beta may be closely related to the pathophysiology of MCD.

Castleman Disease↗
PubMed1994

Acidification of phagosomes and degradation of rod outer segments in rat retinal pigment epithelium.

PURPOSE: The authors investigated the phagocytic processes of the rod outer segments (ROS) in rat retinal pigment epithelium (RPE) cells, and the appearance of lysosomal enzymes, acidification, and degradation of the contents in the phagolysosomes. In particular, they examined the effect of bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, on the degradation of ROS in the RPE cells in vivo. METHODS: A lysosomal enzyme (cathepsin D), a lysosomal membrane protein (LGP107), and opsin were localized in the RPE cells by the immunogold electron microscopic technique. Bafilomycin A1 was injected into the vitreous, and acidification of the phagosomes was measured in vivo by injecting 3-[2,4-dinitroanilino]3'amino-N-methyldipropylamine (DAMP) in the vitreous and detecting the accumulation of DAMP in the phagolysosomes using anti-dinitrophenol antibody. RESULTS: Opsin was abundantly detected in phagosomes that did not contain cathepsin D, but the immunolabeling of opsin rapidly disappeared soon after the appearance of cathepsin D. By double staining with cathepsin D and DAMP, it was shown that the pH of the phagosomes dramatically decreased after fusion with lysosomes. When bafilomycin A1 was injected into the vitreous, many large phagolysosomes containing cathepsin D appeared in the RPE cells, in which the immunoreactivity of opsin was well preserved. CONCLUSIONS: Degradation of opsin and acidification proceeded almost parallel with the appearance of cathepsin D in the phagolysosomes. Bafilomycin A1 did not inhibit the fusion of phagosomes with lysosomes, but it increased intraphagosomal pH and markedly inhibited the degradation of ROS in the phagolysosomes. This result indicates that vacuolar-type H(+)-ATPase is essential for acidifying the lumen of phagolysosomes and subsequent protein degradation of ROS in the RPE cells.

Animals↗
PubMed1994

Xanthogranulomatous cholecystitis masquerading as gallbladder carcinoma.

We herein present a case of xanthogranulomatous cholecystitis which involved both the liver and transverse colon, clinically mimicking gallbladder carcinoma. Such cases may sometimes be judged inoperable due to extensive extra-gallbladder invasion, and thus it is necessary for physicians to take this lesion into consideration when making a diagnosis. An intraoperative biopsy is necessary, therefore, even when the features seem to clearly indicate inoperable carcinoma.

Aged↗
PubMed1993

Correlation between phospholipase A2 activity and intra-Golgi protein transport reconstituted in a cell-free system.

A wide variety of phospholipase A2 inhibitors blocks intra-Golgi protein transport reconstituted in a cell-free system. Phospholipase A2 activity detectable under the protein transport assay conditions is actually inhibited by the inhibitors. There is a good correlation between the inhibition of protein transport and that of phospholipase A2 activity. Prolactin secretion from GH3 cells is also blocked by a membrane-permeable phospholipase A2 inhibitor, suggesting the physiological relevance to inhibition of protein transport in vitro by phospholipase A2 inhibitors.

Acetylglucosamine↗
PubMed1993

Inhibitors of vacuolar-type H(+)-ATPase suppresses proliferation of cultured cells.

We investigated effects of bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase (V-ATPase), and its analogues on proliferation of various cultured cells. The proliferation of the various cell lines was suppressed by adding bafilomycin A1 to the culture medium. This inhibitory effect appeared at a concentration of nanomolar order and was dose dependent. Although the suppression was reversible, the drug exerted not only suppression of the proliferation but also death to some cell lines. Drug concentration required for 50% inhibition of the cell proliferation during 48 h differed markedly depending on cell species and the sensitivity appears to increase by the transformation of the cells. Two derivatives of concanamycin A, an analogue of bafilomycin A1, also inhibited strongly V-ATPase in vitro and in vivo, and simultaneously cell proliferation. Two concanamycin A derivatives which have lost inhibitory effect on V-ATPase lost inhibitory effect on cell proliferation as well. These results suggest that V-ATPase is involved in the machinery maintaining the cell proliferation.

Adenosine Triphosphatases↗
PubMed1993

Immunoelectron microscopic localization of the HPC-1 antigen in rat cerebellum.

HPC-1 antigen is a neuron-specific 34 kDa protein, identical to p35A (syntaxin), and is thought to play important roles in docking or fusion of synaptic vesicles to presynaptic active zones. In the present study we analyze the distribution of HPC-1 antigen in rat cerebellum by a cryoimmunogold technique using an antibody against the fusion protein of beta-galactosidase and the HPC-1 antigen. HPC-1 antigen was detected at high density on the plasma membranes and synaptic vesicles of presynaptic boutons which formed synapses with dendrites of Purkinje cells, and on the plasma membranes of parallel fibres in the cerebellar molecular layer. In the granule cell layer, gold particles were also detected on the endoplasmic reticulum, nuclear membranes and the plasma membranes of granule cells. Presynaptic membranes and synaptic vesicles in glomeruli were also labelled by gold particles. To determine the topology of HPC-1 antigen on the membranes, the synaptosome fraction prepared from rat cerebellum was embedded in agarose, and processed for the pre-embedding protein A-gold technique. Intact synaptosomes were not labelled by gold particles. However, when fixed in hypotonic fixative to rupture plasma membranes, or when ruptured after fixation in normotonic fixative, the cytoplasmic surfaces of presynaptic membranes and synaptic vesicles were labelled by gold particles. These results suggest that most of the epitopes of HPC-1 antigen are located on the cytoplasmic surface of plasma membranes and synaptic vesicle membranes.

Animals↗
PubMed1993

Microsomal aldehyde dehydrogenase or its cross-reacting protein exists in outer mitochondrial membranes and peroxisomal membranes in rat liver.

We investigated the subcellular distribution of microsomal aldehyde dehydrogenase (msALDH) in rat liver and revealed by the immunoblotting method that msALDH or a cross-reacting 54-kDa protein(s) exists in the outer mitochondrial membranes and peroxisomes. Anti-msALDH antibody markedly inhibited the decanal aldehyde dehydrogenase activity of the outer mitochondrial membranes as well as that of the microsomes. Immunogold electron microscopic observations showed that gold particles are localized over the ER, outer mitochondrial membranes and peroxisomal membranes. These results suggest that msALDH or its cross-reacting related protein is distributed not only in the ER membranes but also in the mitochondrial outer membranes and peroxisomal membranes.

Aldehyde Dehydrogenase↗
PubMed1993

[An adult case of acute lymphoblastic leukemia preceded by aplasia resembling aplastic anemia].

Although aplastic anemia (AA) is well known to precede acute leukemia, commonly acute myeloblastic leukemia, an adult case of acute lymphoblastic leukemia (ALL) preceded by aplasia similar to severe AA is very rare. An 18-year-old female was admitted to our hospital for scrutiny of pancytopenia in October 3, 1991. She was diagnosed as severe AA because of severe bone marrow hypoplasia and no abnormal or dysplastic cell. Recovery of hematopoiesis was achieved by pulse therapy of methylprednisolone combined with granulocyte colony stimulating factor (G-CSF). 3 months after AA onset, she was readmitted because of high fever and paralytic ileus. Then, she was diagnosed as ALL (L1; common ALL) and was successfully treated by remission induction chemotherapy. Retrospectively, this case was atypical AA with respect to serum iron and LDH level.

Adolescent↗
PubMed1993

Inhibition of intracellular transport of newly synthesized prolactin by bafilomycin A1 in a pituitary tumor cell line, GH3 cells.

We have investigated the effects of bafilomycin A1, a specific inhibitor of vacuolar type H(+)-ATPase, on the secretion and intracellular distribution of prolactin in cultured rat pituitary tumor cells (GH3 cells). Pulse-labeling the cells with L-[35S]methionine for 5 min and subsequently incubating in chase medium containing 1 microM bafilomycin A1 showed inhibition of basal secretion of labeled prolactin. The inhibition of the secretion by the drug was clearly observed when it was added within 7.5 min after the pulse-labeling, whereas inhibition was barely observed when added at 22 min. When the pulse-labeled cells were chased with 1 microM bafilomycin A1 for 1 h and then washed and incubated in the presence of 10 micrograms/ml brefeldin A (BFA) for 2 h, BFA barely affected the secretion during the latter 2 h period. This result suggested that the labeled prolactin had passed through a BFA-sensitive step(s) in the intracellular transport during the treatment with 1 microM bafilomycin A1. Immunofluorescence microscopy and immunogold electron microscopy revealed that, when the cells were incubated with 0.1 to 1.0 microM bafilomycin A1, small, dense secretory granules containing prolactin decreased markedly, and numerous large vacuoles appeared, which also contained prolactin, and were partially coated with clathrin-like materials. The Golgi apparatus itself was preserved except for some dilatation of the trans-Golgi cisternae and trans-Golgi network (TGN) where these vacuoles were likely to be formed. These results suggest that acidification in immature secretory granules generated by a vacuolar type H(+)-ATPase is necessary for the intracellular transport of prolactin, maturation and concentration processes of the secretory granules.

Animals↗
PubMed1992

Non-lysosomal degradation of misfolded human lysozymes with and without an asparagine-linked glycosylation site.

Human lysozyme is a monomeric secretory protein composed of 130 amino acid residues, with four intramolecular disulfide bonds and no oligosaccharides. In this study, a mutant protein, [Ala128] lysozyme, which cannot fold because it lacks a disulfide bond, Cys6-Cys128, was expressed in mouse fibroblasts and was found to be mostly degraded in the cells, whereas the control wild-type lysozyme was quantitatively secreted into the media. The degradation of [Ala128]lysozyme was independent of the transport from the endoplasmic reticulum to the Golgi apparatus. The degradation was greatly inhibited by incubation of cells at 15 degrees C, but was minimally affected by treatment of cells with the lysosomotropic agent, chloroquine, implying a non-lysosomal process. Additional mutations (Gly48-->Ser or Met29-->Thr) were created to make asparagine-linked (N-linked) glycosylation site in the [Ala128]lysozyme, and the resultant double mutants, [Ser48, Ala128]lysozyme and [Thr29, Ala128]lysozyme, were analyzed with respect to their intracellular degradation. These mutant proteins were susceptible to N-linked glycosylation, and were degraded in a similar manner to that of [Ala128] lysozyme, except that the onset of degradation of [Ser48, Ala128]lysozyme and [Thr29, Ala128] lysozyme, but not of [Ala128]lysozyme, was preceded by a lag period of up to 60 min. Furthermore, the degradative double mutants, [Ser48, Ala128]lysozyme and [Thr29, Ala128]lysozyme, were glycosylated post-translationally as well as co-translationally. These observations suggest that there is some interaction between the mechanisms of glycosylation and degradation.

Animals↗
PubMed1992

Two forms of the low-affinity Fc receptor for IgE differentially mediate endocytosis and phagocytosis: identification of the critical cytoplasmic domains.

We have previously identified two species of the low-affinity human Fc receptor for IgE, Fc epsilon RIIa and Fc epsilon RIIb, which differ only in a short stretch of amino acids at the N-terminal cytoplasmic end. Their differential expressions on B cells and monocytes suggest that Fc epsilon RIIa and Fc epsilon RIIb are involved in B-cell function and IgE-mediated immunity, respectively. Here we show that Fc epsilon RII-mediated endocytosis is observed only in Fc epsilon RIIa-expressing cells, whereas IgE-dependent phagocytosis is observed only in Fc epsilon RIIb-expressing cells, demonstrating the functional difference between Fc epsilon RIIa and Fc epsilon RIIb. Furthermore, site-directed mutagenesis revealed that the tyrosine residue in the Fc epsilon RIIa-specific region is important for endocytosis, and the Asn-Pro residues in the Fc epsilon RIIb-specific region are required for phagocytosis. These findings suggest that endocytosis and phagocytosis are functionally separable phenomena involving distinct amino acid residues.

Amino Acid Sequence↗
PubMed1992

Quantitative immunogold localization of Na, K-ATPase along rat nephron.

Ultrastructural localization of Na, K-ATPase alpha-subunit along rat nephron segments was investigated quantitatively by immunogold electron microscopy on LR-White ultrathin sections using affinity-purified antibody against alpha-subunit of the enzyme. Ultrathin sections were incubated with the antibody at a saturation level and the number of gold particles bound per micron of the plasma membrane (particle density) of the tubular epithelial cells from the proximal tubule to the collecting duct was determined. In all the tubular epithelial cells, gold particles were located exclusively on the basolateral surface, and no significant binding of gold particles to the apical surface was observed. Distribution of gold particles on the basolateral membranes was quite heterogeneous; lateral membranes and infolded basal membranes were highly labeled, whereas the basal membranes which are in direct contact with the basal lamina were scarcely labeled. The average particle density on the basal surface was highest in the distal straight tubule cells (11.4 units), very high in the distal convoluted tubule cells (9.8 units), intermediate in the proximal tubule cells (3.3 units), in the connecting tubule cells (4.3 units), and in the principal cells of the collecting duct (5.6-3.8 units), low in the thin limb of Henle's loop (1.0 unit), and at the control level in the intercalated cells in the connecting and collecting duct. The relative number of gold particles/mm nephron segment and the relative number of gold particles in the various nephron segments were calculated using quantitative morphological data. The estimated distribution profile of the former was in good agreement with the Na, K-ATPase activity profile in rat nephron, which was determined biochemically with a microenzymatic method.

Animals↗
PubMed1992

Heavy chain binding protein (BiP/GRP78) and endoplasmin are exported from the endoplasmic reticulum in rat exocrine pancreatic cells, similar to protein disulfide-isomerase.

Previously we found that in rat exocrine pancreatic cells, protein disulfide-isomerase (PDI), one of the major resident proteins in the lumen of the endoplasmic reticulum (ER) of many cells, is localized not only in the ER but also in the Golgi apparatus, secretory granules, plasma membranes, and even in the glandular lumens, despite possessing the ER retention signal KDEL (Lys-Asp-Glu-Leu) at the carboxyl terminus. In this report, we examined whether other ER luminal proteins bearing the KDEL signal at their C-termini, such as BiP/GRP78 and endoplasmin/GRP94 are also exported from the ER. We prepared two kinds of affinity-purified polyclonal antibodies; one against a synthetic peptide with 12 amino acids which is identical to the carboxyl terminus of BiP and another against purified endoplasmin. Immunoblot analysis using these two antibodies showed that BiP and endoplasmin exist in both the plasma membrane and the microsomal fractions, similar to the intracellular distribution of PDI in rat exocrine pancreas. The ratios of the amount of the three proteins in the two fractions, however, were variable, suggesting that the KDEL-bearing proteins such as PDI, BiP, and endoplasmin are exported from the ER with different efficiencies. Postembedding protein A-immunogold electron microscopy revealed that endoplasmin was exported from the ER and secreted to the extracellular space. The secretion of PDI in rat pancreatic lobules was inhibited by Brefeldin A (BFA) and by guanidino acid esters (FOY-305), which are known to be the inhibitors of the intracellular transport. Taken together with the previous immunogold electron microscopic analyses by Akagi et al. (1988), it is strongly suggested that in rat exocrine pancreatic cells PDI and the other KDEL-bearing proteins found in the extracellular space were not artificially released by cell damage during incubation but were secreted via the normal secretory pathway.

Amino Acid Sequence↗