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Biomedical subjects

K Toyoshima

Publications and source records attributed to K Toyoshima.

At least 199 records · Page 11Linked to original sources
PubMed1989

Dense-cored vesicles and unusual lamellar bodies in type III gustatory cells in taste buds of rabbit foliate papillae.

Some type III cells in taste buds of rabbit foliate papillae have greatly increased numbers of dense-cored vesicles. Such cells also contain unusual lamellar bodies that resemble those in alveolar type II cells; they consist of alternating dense and light layers with a periodicity of about 4.4 nm. The precise relationship between the vesicles and the lamellar bodies is unknown.

Animals↗
PubMed1989

Chemoreceptive and mechanoreceptive paraneurons in the tongue.

Chemoreceptive and mechanoreceptive paraneurons in the tongue include gustatory cells and basal cells of the taste buds, Merkel cells in the lingual epithelium and Merkel or Grandry corpuscles in avian subepithelial connective tissue. Neuron-specific enolase immunoreactivity is recognized in the basal cells, a type of Merkel cells, in the taste buds of teleost fishes and amphibia, certain taste bud cells of mammals and the Merkel cells in birds. The present study also concerns itself with the ultrastructural features of the gustatory cells of the rabbit taste buds, and the Merkel cells of the finch tongue. The functional significance of the dense-cored granules in the gustatory cell is still enigmatic. On the other hand, the dense-cored granules in the Merkel cells may have dual functions storing both neurotransmitters and local hormones. Shortly after giving a mechanical stimulus to the finch tongue, we could demonstrate massive exocytotic changes of the Merkel cell granules.

Amphibians↗
PubMed1989

Bronchoconstrictive effect of ultrasonic nebulized distilled water on asthmatic children.

We studied the airway responsiveness of asthmatic and normal children to ultrasonic nebulized distilled water (UNDW inhalation test). It was found that this stimulus induced a fall in FEV1 (forced expiratory volume in 1 s) in asthmatic children, but little fall in normal children. This airway response was shown to be reproducible at about 2-week intervals. The more severe the asthma, the higher the percentage of the responders to the UNDW inhalation test, and the greater the fall in FEV1. The results of the UNDW inhalation test did not correlate with that of acetylcholine inhalation test or of exercise-induced asthma (EIA). UNDW-induced bronchoconstriction was inhibited by premedication with disodium cromoglycate (DSCG) (20 mg) or inhaled ipratropium bromide (40 micrograms). Jet-nebulized distilled water induced little fall in FEV1 in asthmatic children. These data suggest that UNDW-induced bronchoconstriction may involve the release of chemical mediators from the mast cells and cholinergic pathways. We conclude that UNDW inhalation test is a safe, less burdensome, and rather convenient method to evaluate clinically nonspecific airway hyperresponsiveness in asthmatic children.

Acetylcholine↗
PubMed1989

C-erbB-2 gene product, a membrane protein commonly expressed on human fetal epithelial cells.

C-erbB-2 is a human proto-oncogene which has homologies with the well known proto-oncogene c-erbB. The c-erbB-2 gene is amplified and overexpressed in some human adenocarcinomas. Its expression, in terms of RNA levels in normal human fetal kidney, lung and liver, has also been reported. In the present study, various fetal tissues from three human abortuses obtained at 9, 14 and 24 weeks of gestation, were studied immunohistologically by the ABC method and immunochemically by Western blot analysis for the distribution of c-erbB-2 gene product at the protein level. A polyclonal antibody raised in rabbit by immunization with a synthetic polypeptide corresponding to part of the predicted intracytoplasmic domain was used. Strong immunoreactivity was observed on the membrane of most of the epithelial cells examined, including transitional cells of the renal pelvis and ureter, glandular cells of the gastrointestinal tract, renal tubuli, bronchi and pancreas, and stratified epithelium of the oral cavity, trachea and esophagus in this gestational period. A much more intense reaction was observed on the basolateral sides than on the apical side of these cells. No immunoreactivity was found in the liver, adrenal gland, striated and smooth muscles, brain, endothelium or fibroblasts. Western blot analysis confirmed increased expression of the c-erbB-2 gene product in fetal kidney and intestine but not in the brain. As the protein seems to be poorly expressed in normal adult epithelial cells except for renal tubuli, the present results suggest that the protein is a membrane-associated receptor protein which controls some specific reaction of fetal epithelium.

Blotting, Western↗
PubMed1989

Characterization and functional allotment of proto-oncogenes belonging to the src family.

Eight proto-oncogenes encode cytoplasmic protein tyrosine kinases whose primary structures are closely related to that of p60proto-src. This group of related genes is called the src-family. Their products share common structures: namely, a glycine residue at position 2 from the N terminus, a unique domain, a modulatory domain (SH2, SH3), a kinase (catalytic) domain, and a regulatory domain. Oncogenic activation of these genes may occur by various mutations such as 1) deletion or substitution of the tyrosine at the C-terminal position, 2) mutation at a defined position in the kinase domain or 3) deletion or mutation in the modulatory domain. The expressions of the proto-oncogenes of this family are tissue specific and are unique for each gene, suggesting functional allotment of these gene products. In the hematopoietic system, the genes appear to be expressed in specific cell lineages. In this paper, the functional allotments of these genes in the hematopoietic system are considered with special reference to the functions of lck, lyn, and fyn in cells of T and B lymphocyte lineages.

Amino Acid Sequence↗
PubMed1989

A mechanism of c-raf-1 activation: fusion of the lipocortin II amino-terminal sequence with the c-raf-1 kinase domain.

In order to understand the mechanism of oncogenic activation, we have analyzed the c-raf-1 gene from the GL-5-JCK human glioblastoma, which underwent rearrangement during transfection experiments. Nucleotide sequencing of cDNA clones derived from the 2.5 kb raf-mRNA, which is a major transcript of raf in NIH3T3 cells transformed with GL-5-JCK DNA, revealed that this mRNA contains sequences derived from the human c-raf-1 gene and the human lipocortin II gene. Translation of the 2.5 kb raf-mRNA predicted a fusion protein consisting of 16 amino-terminal amino acid residues of the lipocortin II and 370 carboxy-terminal amino acid residues of the c-raf-1 protein which contains the kinase domain. Expression of the lipocortin II-raf cDNA using the murine sarcoma virus long terminal repeat as promoter resulted in the transformation of NIH3T3 cells.

Annexins↗
PubMed1989

Regulation of expression and transforming ability of the c-erbB-2 gene.

The human c-erbB-2 gene encodes a growth factor receptor-like protein that is highly homologous to the epidermal growth factor (EGF) receptor. Previous studies have shown that the c-erbB-2 gene is preferentially expressed in fetal epithelial cells, suggesting that the ligand of the gene product controls the growth of these cells. Molecular analysis of the c-erbB-2 promoter region revealed three regulatory systems: they are a typical set of CCAAT and TATA boxes, GC boxes, and Myb binding sites. Binding of the c-myb and B-myb gene products to the promoter region seems to down-regulate the c-erbB-2 mRNA synthesis. Elevated expression of this gene is often associated with adenocarcinomas such as breast cancers and stomach cancers and is correlated with the spread of the former. Involvement of the c-erbB-2 gene in the tumor development is further demonstrated by induction of B-lymphomas in transgenic mice carrying normal or mutated forms of this c-erbB-2 gene. In addition, the transforming potential of the c-erbB-2 gene is closely correlated with elevated tyrosine kinase activity of the gene product, which is negatively regulated by its carboxy-terminal sequence of about 230 amino acid residues.

Animals↗
PubMed1989

Modified endoplasmic reticulum in taste bud cells of the Japanese monkey.

Type III cells (receptor cells) in taste buds of vallate papillae in the Japanese monkey often have one or more cytoplasmic bodies composed of modified smooth endoplasmic reticulum in the form of concentric smooth-surfaced cisternae, up to 18 in number. The most peripheral cisternae may be in continuity with rough endoplasmic reticulum (RER). Type II cells have dilated RER cisternae that often contain crystalline plates with an axial periodicity that ranges from 17 to 27 nm. These observations show that both type III and type II cells of the Japanese monkey possess the cytoplasmic machinery to carry out several secretory functions.

Animals↗
PubMed1988

Identification of two novel members of erbA superfamily by molecular cloning: the gene products of the two are highly related to each other.

Two v-erbA-related genes, named ear-2 and ear-3, have been identified in the human genome and characterized by cDNA cloning. These genes are predicted to encode proteins that are very similar in primary structure to receptors for steroid hormones or thyroid hormone (T3). In addition, amino acid sequences of the ear-2 and ear-3 gene products are very similar each other especially at the DNA binding domain (86% homology) and at the putative ligand binding domain (76% homology). Northern hybridization with ear DNA probes of RNAs from various tissues of a human fetus reveals that the expression of ear-2 is high in the liver whereas the expression of ear-3 is relatively ubiquitous. Hybridization analysis of DNAs from sorted chromosomes shows that the ear-2 gene is located on chromosome 19 and ear-3 on chromosome 5, indicating that the two genes are clearly different from each other.

Alpharetrovirus↗
PubMed1988

Peptide antibodies to the human c-fyn gene product demonstrate pp59c-fyn is capable of complex formation with the middle-T antigen of polyomavirus.

The c-fyn proto-oncogene is a member of a family of closely related genes of which c-src is the prototype. Using peptide antibodies which had been raised against sequences predicted to be specific for the human c-fyn gene product, the c-fyn protein was identified. It is a tyrosine kinase with apparent mol. wt of 59 kd that is also phosphorylated and myristylated. Like pp60c-src and pp62c-yes, pp59c-fyn is able to form a stable complex with middle-T antigen, the transforming protein of polyomavirus. The transformation-defective middle-T mutant NG59, which is unable to associate stably with pp60c-src does not associate with pp59c-fyn. In contrast to pp60c-src, complex formation with middle-T antigen does not lead to a significant increase in the tyrosine kinase activity of pp59c-fyn. These findings lead us to suggest that middle-T mediated transformation may be a consequence of the deregulation of several members of the src-family of protein tyrosine kinases.

Animals↗
PubMed1988

Depression in gene expression for poly(ADP-ribose) synthetase during the interferon-gamma-induced activation process of murine macrophage tumor cells.

A 2.7-kb cDNA clone coding for bovine poly(ADP-ribose) synthetase was isolated from a lambda gt11 expression library by direct immunological screening with an antiserum to the enzyme. The cDNA hybridizes to an approximately 3.8-kb bovine thymus polyadenylated RNA, which translates an immunoprecipitable 120-kDa protein with the antibody to the enzyme. The partial DNA sequence of the cDNA was determined and portions of the predicted amino acid sequence matched the sequence of 26 amino acids at the N terminal of the 41-kDa alpha-chymotryptic fragment and two cyanogen-bromide-cleaved peptides of the enzyme. A subcloned fragment from the coding region of the cDNA was used as a probe to estimate the level of mRNA for the enzyme during the interferon-gamma-induced activation process of the murine macrophage tumor P388D1 cell line. The amount of mRNA for the enzyme decreased nearly completely within 24 h after incubation in a medium containing interferon-gamma, while mRNA of the Ia antigen, one of the major histocompatibility gene products, was increased in the macrophage tumor cells by interferon-gamma as confirmed by the I-A beta cDNA as a probe. These results suggest that the gene expression for poly(ADP-ribose) synthetase is depressed during the interferon-gamma-induced activation process of macrophage tumor cells.

Amino Acid Sequence↗
PubMed1988

Nucleotide sequence and chromosomal mapping of the human c-yes-2 gene.

We molecularly characterized the second gene, c-yes-2, of two copies of yes-related genes which we previously found to contain in the human genome. First, nucleotide sequence analysis revealed that the c-yes-2 gene is a pseudogene of the c-yes-1 gene. Second, by using two independent methods, hybridization of both DNAs from sorted chromosomes and metaphase spreads with c-yes-2 DNA, we assigned the c-yes-2 gene to chromosome 22q11.2. This chromosomal localization is consistent with that given in our previous report. The failure of proper mapping in our experiment might have been caused by instability of hybrid cell clones.

Base Sequence↗
PubMed1988

Tumor promoter and epidermal growth factor stimulate phosphorylation of the c-erbB-2 gene product in MKN-7 human adenocarcinoma cells.

Treatment of human adenocarcinoma MKN-7 cells with epidermal growth factor (EGF) or phorbol tetradecanoate acetate (TPA) stimulated phosphorylation of the c-erbB-2 gene product. EGF induced a rapid increase in phosphotyrosine followed by relatively gradual increases in phosphoserine and phosphothreonine. On the other hand, the TPA-induced increase in phosphorylations occurred exclusively on serine and threonine residues. Tryptic phosphopeptide mapping analysis suggested that treatments with EGF and TPA induced phosphorylation of many common sites in the c-erbB-2 gene product. However, in contrast to TPA, EGF increased the phosphorylation of the c-erbB-2 protein in cells whose protein kinase C had been down-regulated by long-term pretreatment with TPA, suggesting that EGF and TPA induce phosphorylation by different mechanisms. Since the c-erbB-2 gene product did not show detectable EGF-binding activity, phosphorylation of tyrosine of the c-erbB-2 gene product might be catalyzed directly by the EGF receptor kinase that was activated by EGF.

Adenocarcinoma↗
PubMed1988

B-raf, a new member of the raf family, is activated by DNA rearrangement.

Complementary DNA clones of a putative transforming gene were isolated from NIH 3T3 cells transformed with human Ewing sarcoma DNA. The gene was termed B-raf because it is related to but distinct from c-raf and A-raf. It appears that substitution in the amino-terminal portion of the normal B-raf protein confers transforming activity to the gene.

Base Sequence↗
PubMed1988

An immunohistochemical demonstration of neuron-specific enolase in the Merkel cells of the frog taste organ.

The Merkel cells in the taste organ of the frog were investigated by immunohistochemistry using neuron-specific enolase (NSE) antiserum. NSE-immunoreactivity was found exclusively in the Merkel cells lying at the base of the taste organ. The distribution and the profiles of the NSE-immunoreactive Merkel cells coincided with serotonin-containing cells previously reported at the same place.

Animals↗