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T Isobe

Publications and source records attributed to T Isobe.

At least 145 records · Page 8Linked to original sources
PubMed1994

A nuclear factor containing the leucine-rich repeats expressed in murine cerebellar neurons.

A nuclear protein, termed leucine-rich acidic nuclear protein (LANP), has been isolated from among rat cerebellar proteins whose expression was transiently increased during an early stage of postnatal development. The amino acid sequence, deduced from its cDNA, showed that LANP contains 247 amino acids consisting of two distinct structural domains: the N-terminal domain characterized by "leucine-rich repeat," which is found in many eukaryotic proteins and which potentially functions in mediating protein-protein interactions, and the C-terminal domain characterized by a cluster of acidic amino acids with a putative nuclear localization signal. Immunohistochemical study using an antibody against LANP revealed that the protein is localized mainly in nuclei of Purkinje cells. In the rat cerebellum on postnatal day 7, LANP mRNA was expressed moderately in the external granule and Purkinje cells and weakly in the internal granule cells. The expression in these cells, especially in Purkinje cells, increased in the second postnatal week and thereafter decreased to an adult level. The structural characteristics, localization, and the stage- and cell type-specific expression suggest a potential role of LANP in a signal transduction pathway that directs differentiation of cerebellar neurons.

Aging↗
PubMed1994

Synergistic activation by Ras and 14-3-3 protein of a mitogen-activated protein kinase kinase kinase named Ras-dependent extracellular signal-regulated kinase kinase stimulator.

We have identified, in Xenopus oocyte cytosol, a protein kinase named REKS (Ras-dependent extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase kinase (MEK) stimulator), which phosphorylates and activates recombinant ERK2 through recombinant MEK in a recombinant GTP gamma S (guanosine 5'-(3-O-thio)triphosphate)-Ras-dependent manner. We show here that this REKS activity is synergistically enhanced by a combination of mammalian recombinant GTP gamma S-KiRas and 14-3-3 protein purified from rat brain. 14-3-3 protein is known to activate tyrosine and tryptophan hydroxylases, to modulate the protein kinase C activity, to stimulate secretion, and to show phospholipase A2 activity per se. 14-3-3 protein did not affect the MEK activity. 14-3-3 protein neither interacted with Ki-Ras nor affected the neurofibromin activity to stimulate the GTPase activity of Ki-Ras under the conditions where the recombinant N-terminal fragment of c-Raf-1 inhibited it. These results suggest that 14-3-3 protein has an additional function in the regulation of the Ras-MEK-ERK cascade pathway through the activation of REKS.

14-3-3 Proteins↗
PubMed1994

Posttranslational processing of a carboxy-terminal propeptide containing a KDEL sequence of plant vacuolar cysteine endopeptidase (SH-EP)

A plant cysteine endopeptidase, designated SH-EP, is a major protease occurring in cotyledons of Vigna mungo seedlings, and acts to degrade seed globulin stored in protein bodies. Here we show that the 43 kDa intermediate of SH-EP formed in the endoplasmic reticulum is transported to protein bodies and processed to the 33 kDa mature form during transport or thereafter, and that the COOH-terminal propeptide of 10 amino acid residues containing a KDEL sequence, which is known as a retention signal for the endoplasmic reticulum lumen, is processed to form the mature SH-EP.

Amino Acid Sequence↗
PubMed1994

Murine cerebellar neurons express a novel gene encoding a protein related to cell cycle control and cell fate determination proteins.

We cloned cDNAs of a novel protein (designated V-1) that has been identified from among the developmentally regulated proteins in the rat cerebellum. Protein sequencing analysis (Taoka, M., Yamakuni, T., Song, S.-Y., Yamakawa, Y., Seta, K., Okuyama, T., and Isobe, T. (1992) Eur. J. Biochem. 207, 615-620) and cDNA sequence analysis revealed that the V-1 protein consists of 117 amino acids and contains 2.5 contiguous repeats of the cdc10/SWI6 motif, which was originally found in the products of the cell cycle control genes of yeasts and the cell fate determination genes in Drosophila and Caenorhabditis elegans. In situ hybridization histochemistry revealed that the expression of the V-1 gene is transiently increased in postmigratory granule cells during postnatal rat cerebellar development and thereafter is markedly suppressed, whereas Purkinje cells constitutively express V-1 mRNA. In contrast, cerebellar granule cells of the staggerer mutant mouse continue to express the V-1 gene even when the granule cells of the normal mouse have ceased to express the V-1 gene, suggesting that the expression of the V-1 gene in granule cells is regulated through the interaction with Purkinje cells. On the basis of these results, we postulate that the V-1 protein has a potential role in the differentiation of granule cells.

Amino Acid Sequence↗
PubMed1994

Covalent structure of bovine brain calreticulin.

The covalent structure of bovine brain calreticulin, a major Ca(2+)-binding protein in the lumen of the endoplasmic reticulum, was determined by analysis of the purified protein. The protein consisted of 400 amino acids, with an N-linked oligosaccharide attached to the polypeptide chain. The polypeptide sequence determined was compatible with the sequence of calreticulin deduced from cDNA of different sources, with a number of differences presumably due to species-specific amino acid substitutions. The protein retained the C-terminal tetrapeptide, KDEL, involved in retention of proteins resident in the endoplasmic reticulum, whereas the N-terminal signal peptide predicted from the cDNA sequence had been removed in the purified protein. The bovine brain protein contained a high-mannose type of oligosaccharide attached to Asn162, which is typical of resident endoplasmic reticulum proteins. The carbohydrate moiety was heterogeneous and had the composition GlcNAc2Man4-9, of which GlcNAc2Man5 was the most abundant in the bovine brain preparation. Glycosylation of calreticulin, however, appeared to be a species-specific modification, as Asn162 is replaced by Asp in the sequences already determined for a number of species. Analysis of the purified protein also identified an intramolecular disulphide bridge between Cys120 and Cys146.

Amino Acid Sequence↗
PubMed1994

A single Arabidopsis GF14 isoform possesses biochemical characteristics of diverse 14-3-3 homologues.

Arabidopsis cDNA clones of GF14 proteins originally were isolated on the basis of their association with the G-box DNA/protein complex by a monoclonal antibody screening approach. GF14 proteins are homologous to the 14-3-3 family of mammalian proteins. Here we demonstrate that recombinant GF14 omega, one member of the Arabidopsis GF14 protein family, is a dimeric protein that possesses many of the attributes of diverse mammalian 14-3-3 homologues. GF14 omega activates rat brain tryptophan hydroxylase and protein kinase C in a manner similar to the bovine 14-3-3 protein. It also activates exoenzyme S of Pseudomonas aeruginosa as does bovine brain factor activating exoenzyme S (FAS), which is itself a member of 14-3-3 proteins. In addition, GF14 omega binds calcium, as does the human 14-3-3 homologue reported to be a phospholipase A2. These results indicate that a single isoform of this plant protein family can have multiple functions and that individual GF14 isoforms may have multiple roles in mediating signal transductions in plants. However, GF14 omega does not regulate growth in an in vivo test for functional similarity to the yeast 14-3-3 homologue, BMH1. Thus, while a single plant GF14 isoform can exhibit many of the biochemical attributes of diverse mammalian 14-3-3 homologues, open questions remain regarding the physiological functions of GF14/14-3-3 proteins.

14-3-3 Proteins↗
PubMed1994

Plasma cell leukemia with myelofibrosis.

We describe a case of plasma cell leukemia associated with myelofibrosis. A 60-year-old woman was admitted due to lumbago and monoclonal hypergammaglobulinemia. Peripheral blood showed about 40% of plasma-cell-like cells. A bone marrow aspiration was dry tap. The patient was diagnosed as having plasma cell leukemia with myelofibrosis by bone marrow biopsy. Plasma cell leukemia as well as myelofibrosis improved with combination chemotherapy using vincristine, pirarubicin, and dexamethasone. However, when plasma cell leukemia became resistant to chemotherapies, myelofibrosis also reappeared. This case strongly suggests the pathogenetic relationship between plasma cell leukemia and myelofibrosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Analysis of schizont antigen of Leucocytozoon caulleryi by SDS-PAGE and western blot.

To investigate the molecular weight of the schizont antigen of Leucocytozoon caulleryi, the schizont antigen was analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and western blot. Thirty to 35 protein bands were detected by SDS-PAGE under reduced condition and ranged from 25 to 300 kDa. Most of them reacted with the sera of infected chickens by Western blot. The bands corresponding to polypeptides of 44, 58, 67 and 180 kDa reacted strongly, however, the bands of 30, 50 and 78 kDa did not react.

Animals↗
PubMed1994

Molecular cloning of rat cDNAs for the zeta and theta subtypes of 14-3-3 protein and differential distributions of their mRNAs in the brain.

We isolated from the rat brain two cDNA clones encoding the zeta and theta subtypes of the 14-3-3 protein. Both clones encoded 245 amino acid sequences, which share a high sequence homology with each other and also with other subtypes of the 14-3-3 protein. The distribution of their mRNAs was determined in the developing brain, by in situ hybridization with subtype-specific oligonucleotide probes. At embryonic day 18, the zeta and theta subtype mRNAs were expressed at high levels throughout the brain and the spinal cord. Distribution patterns of the two mRNAs were distinct in the brain at postnatal day 21. The zeta subtype mRNA was distributed widely in the brain gray matter, and high levels of the transcripts were detected in various brain regions, including the neocortex, hippocampus, caudate-putamen, thalamus, cerebellar cortex, and several brainstem nuclei. On the other hand, high signal levels of the theta subtype mRNA in the gray matter were restricted to the cerebellar cortex and the hippocampus. In addition, significant signals for the theta subtype mRNA were found over the white matter, where cell bodies of glial cells are populated. The wide gene expression of the zeta and theta subtypes suggests their fundamental and essential role in the brain function, but the degrees of functional involvement by the respective subtypes would be heterogeneous between neuron and glia, and also among neuron types.

14-3-3 Proteins↗
PubMed1994

Prognostic significance of p53 and ras gene abnormalities in lung adenocarcinoma patients with stage I disease after curative resection.

We investigated the prognostic significance of p53 gene abnormalities and ras gene mutations in patients with curatively resected stage I lung adenocarcinoma. Formalin-fixed and paraffin-embedded tissues were obtained from 30 patients who had undergone curative resection for stage I lung adenocarcinoma. Abnormalities of the p53 gene were detected using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis and immunohistochemistry and ras mutations were detected using PCR-restriction fragment length polymorphism (RFLP) analysis. Both univariate and multivariate analyses were performed to assess the relationship between the presence of abnormalities of these genes and the patients' disease-free survival. Eleven tumors (37%) had mutated p53 sequences and 11 (37%) showed p53 overexpression. A total of 15 tumors (50%) had p53 gene abnormalities and the concordance rate was 73%. Seven tumors (23%) showed mutated ras sequences. The univariate analysis revealed that the disease-free survival of patients with any p53 abnormality was shorter than that of those without abnormalities (P = 0.02, generalized Wilcoxon test), and survival of those with p53 protein overexpression was more significantly shorter (P = 0.003, generalized Wilcoxon test). Multivariate analysis using the Cox proportional hazards model indicated that the presence of p53 abnormalities was a significantly (P = 0.01) unfavorable prognostic factor. There was no significant correlation between the presence of ras mutation and survival. These results suggest that analysis of the p53 gene may be helpful for the selection of high-risk patients for clinical trials of adjuvant therapy for stage I lung adenocarcinoma.

Adenocarcinoma↗
PubMed1994

Ten-year survival and prognostic factors in multiple myeloma. Japan Myeloma Study Group.

Among 1119 Japanese patients with symptomatic multiple myeloma diagnosed between 1965 and 1981, 38 (3.4%) survived more than 10 years. Younger age, low tumour mass (absence of severe anaemia, hypercalcaemia, renal failure, and multiple bone lesions), low plasma cell percentage in bone marrow, mature and intermediate myeloma according to Greipp's criteria, and a positive response to subsequent treatment, were related to long-term survival according to univariate analysis. Multivariate logistic regression analysis indicated younger age and low tumour mass as pretreatment characteristics to be related to long-term survival. Prognostic factors proposed applicable to myeloma were also related to 10-year survival.

Aged↗
PubMed1994

[A suspected case of T0N1M0 small cell carcinoma of the lung].

A 51-year-old man was admitted to our hospital with a chief complaint of cough. His chest X-ray and CT scan revealed enlargement of a left hilar lymph node. However, no primary lesion was apparent in the rest of the lung. Bronchofiberscopic findings were essentially normal. At surgery the mass was determined to be an enlarged lymph node (No. 11). No apparent malignant lesion was identified in the lung. Postoperative pathological examination showed small cell carcinoma in a part of the No. 11 lymph node. Despite a thorough systemic examination, no primary foci were detected. We have been following up this patient with chemotherapy for the approximately 2 year period since the operation, but no primary lesions have been detected as yet. Therefore, we speculate that this patient is a very rare case of primary unknown T0N1M0 lung cancer.

Carcinoma, Small Cell↗
PubMed1994

Chronic myelomonocytic leukemia following prolonged alkylating agent therapy for multiple myeloma.

A 35-year-old male presented with chronic myelomonocytic leukemia (CMMoL) after 6.5 years of alkylating agent therapy for IgG-kappa type multiple myeloma. The total dose of melphalan was 0.648 g. CMMoL was stable with weekly injection of alpha-interferon for one year. Thereafter, monocytosis and thrombocytopenia aggravated, and the patient died of disseminating intravascular coagulation. Prolonged drug therapy can induce CMMoL, as well as other myelodysplastic syndromes.

Adult↗
PubMed1993

Use of glucomannan for the separation of DNA fragments by capillary electrophoresis.

Glucomannan, a natural polysaccharide extracted from Amorphophallus konjac, was employed as a sieving additive for the separation of restriction DNA fragments in capillary electrophoresis. A stable solution of entangled glucomannan was successfully prepared under mild conditions. The separation capillary filled with 0.25% glucomannan exhibited excellent resolution and reproducibility on separation of DNA fragments over the range of ca. 1400 base pairs. The separation was dependent on the size of the fragments, which allowed the determination of the size of separated DNAs directly from the migration time. In addition to these separation characteristics, glucomannan has practical advantages in its chemical stability, non-toxicity and ease of handling. Because the method is applicable to the separation and characterization of the DNA fragments generated by digestion with restriction enzymes or produced by polymerase chain reactions, it is concluded that glucomannan is a good alternative to the conventional sieving additives for capillary electrophoresis, such as polyacrylamide and hydroxymethylcellulose.

Bacteriophage phi X 174↗
PubMed1993

Ribosome-binding protein p34 is a member of the leucine-rich-repeat-protein superfamily.

Protein p34 is a non-glycosylated membrane protein characteristic of rough microsomes and is believed to play a role in the ribosome-membrane association. In the present study we isolated cDNA encoding p34 from a rat liver cDNA library and determined its complete amino acid sequence. p34 mRNA is 3.2 kb long and encodes a polypeptide of 307 amino acids with a molecular mass of about 34.9 kDa. Primary sequence analysis, coupled with biochemical studies on the topology, suggested that p34 is a type II signal-anchor protein; it is composed of a large cytoplasmic domain, a membrane-spanning segment and a 38-amino-acid-long luminally disposed C-terminus. The cytoplasmic domain of p34 has several noteworthy structural features, including a region of 4.5 tandem repeats of 23-24 amino acids. The repeated motif shows structural similarity to the leucine-rich repeat which is found in a variety of proteins widely distributed among eukaryotic cells and which potentially functions in mediating protein-protein interactions. The cytoplasmic domain also contains a characteristic hydrophilic region with abundant charged amino acids. These structural regions may be important for the observed ribosome-binding activity of the p34 protein.

Amino Acid Sequence↗
PubMed1993

Demonstration of the phosphorylation-dependent interaction of tryptophan hydroxylase with the 14-3-3 protein.

The molecular mechanism of the phosphorylation-dependent activation of tryptophan hydroxylase is studied with respect to the role of the 14-3-3 protein. Reexamination of the system reconstituted with the purified TRH and the 14-3-3 protein showed that the level of the TRH activity correlated with the extent of the Ca2+/calmodulin- or the cAMP-dependent phosphorylation in TRH. The experiment confirmed the requirement of the 14-3-3 protein for the activation, but the 14-3-3 protein added into the assay mixture did not affect either the extent nor the specificity of the phosphorylation. However, the analysis of the assay mixture on a pteridine-based affinity column indicated the formation of a complex between TRH and the 14-3-3 protein, where the complex formation depended on the phosphorylation of TRH. The complex between the phosphorylated TRH and the 14-3-3 protein could also be detected by analysis of crude brainstem extract previously phosphorylated by endogeneous Ca2+/calmodulin-dependent protein kinase. The 14-3-3 protein, therefore, appears to be a phosphorylation-dependent TRH-binding protein whose interaction causes the activation of TRH.

14-3-3 Proteins↗
PubMed1993

Developmental regulation of neuronal expression for the eta subtype of the 14-3-3 protein, a putative regulatory protein for protein kinase C.

An in situ hybridization technique was applied to rat nervous tissues, to analyse the developmental changes in expression for the eta subtype mRNA of 14-3-3 protein, a putative regulatory protein for protein kinase C. Although signal levels of the eta subtype mRNA were low in mitotic cells in the ventricular zone, most neurons displayed a marked increase at their definitive location in the mantle zone. In general, neurons in the spinal ventral horn and peripheral ganglia showed this increase at E13-E15, those in the telencephalon, diencephalon, midbrain, pons and medulla oblongata at E18-P1, and the cerebellar Purkinje cells at P7-P14. It is at these developmental stages when neuronal differentiation including axonal and dendritic growth and ramification occurs actively. Subsequently high levels of the eta subtype mRNA were maintained until the adult stage in projection type neurons possessing larger cell bodies and highly developed dendritic fields, such as the olfactory mitral cells, hippocampal pyramidal cells, cerebellar Purkinje cells, and motor neurons in the brainstem and spinal cord. However, the signal levels decreased until the adult stage in smaller projection type neurons. On the other hand, the signal levels in local circuit type neurons were consistently low throughout development. These findings suggest that gene expression for the eta subtype mRNA of the 14-3-3 protein is regulated in close relation to both neuron types and their cytodifferentiation.

14-3-3 Proteins↗