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109 results on '"Ikehara, Yukio"'

8. Extracellular nucleotide signaling in adult neural stem cells: synergism with growth factor-mediated cellular proliferation

Author

Mishra, Santosh K., primary, Braun, Norbert, additional, Shukla, Varsha, additional, Füllgrabe, Marc, additional, Schomerus, Christof, additional, Korf, Horst-Werner, additional, Gachet, Christian, additional, Ikehara, Yukio, additional, Sévigny, Jean, additional, Robson, Simon C., additional, and Zimmermann, Herbert, additional

Published
2006
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33. Weakly basic amines inhibit the proteolytic conversion of proalbumin to serum albumin in cultured rat hepatocytes.

Author

Oda, Kimimitsu and Ikehara, Yukio

Subjects
*AMINES, *PROTEOLYSIS, *PROTEIN metabolism, *PROTEOLYTIC enzymes, *ALBUMINS, *SERUM
Abstract

Effects of weak amines on the proteolytic conversions of proalbumin to serum were studied in primary culture of rat hepatocytes. In control culture proalbumin was converted to serum albunin was inhibited and proalbunin per se was released into, medium. A similar inhibition of the processing was also observed in the presence of other amines such as methylamine and NH4Cl. Thus weak amines mimic the carboxylic ionophore monensin with regard to the effet on proalbunin conversion [Oda & Ikehara (1982) Biochem, Biophys. Res. Commun, 105, 766-772]. Since proteolytic conversion of proalbunin is believed to occur at the Golgi complex, these results suggest that weakly basic amines perturb the Golgi complex in addition to lysosomes and endosomes. [ABSTRACT FROM AUTHOR]

Published
1985
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34. Multiple Forms of Rat-Serum α¹-Protease Inhibitor: Involvement of Sialic Acid in the Multiplicity of Three Original Forms.

Author

Ikehara, Yukio, Miyasato, Mihoko, Ogata, Shigenori, and Oda, Kimimitsu

Subjects
*GENETICS, *PROTEASE inhibitors, *BIOLOGY
Abstract

Focuses on α&supl;-protease inhibitors. Determination of the genetic type of the protease inhibitor by autosomal co-dominant alleles; Presence of multiple genetic variants of the protease inhibitor. [ABSTRACT FROM AUTHOR]

Published
1981
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35. Isolation and characterization of a rat liver alkaline phosphatase gene.

Author

Toh, Yasushi, Yamamoto, Mikio, Endo, Hideya, Misumi, Yoshio, and Ikehara, Yukio

Subjects
ALKALINE phosphatase, RATS, LIVER, ANTISENSE DNA, MESSENGER RNA, NUCLEOTIDES
Abstract

Structural analysis of 55 nearly full-length cDNA clones revealed heterogeneity in the 5'-untranslated regions of rat liver alkaline phosphatase mRNAs. The 5' extremities diverged into two totally unrelated sequence stretches at the position 88 nucleotides upstream of the initiation codon ATG. These two sequences, referred to as E1 and E2, were assigned on the genome about 36 000 base pairs (36 kbp) and 10 kbp upstream, respectively, of the exon coding for the 5'-most part of the common region. The gene consisted of 13 exons, including E1 and E2, and spanned about 56 kbp. The 11 exons (E3 to E13) following E1 and E2 were shared in common by the El-type and the E2-type mRNAs. Analyses by SI nuclease mapping and primer extension revealed the presence of two independent transcription-initiation sites specific to each of the El and E2 sequences. These results are interpreted as indicating a possible alternative usage of two leader exons, hence the presence of two independent promoters. Structural features of these putative promoters are described in the context of transcriptional fundamental and regulatory cis-elements. [ABSTRACT FROM AUTHOR]

Published
1989
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36. Structural analysis of the asparagine-linked oligosaccharides of rat haptoglobin metaholically labeled in a hepatocyte culture system.

Author

Ogata, Shigenori, Misumi, Yoshio, Miki, Koichiro, and Ikehara, Yukio

Subjects
OLIGOSACCHARIDES, HAPTOGLOBINS, CARRIER proteins, CHROMATOGRAPHIC analysis, GLYCOSIDES, COLLOIDS
Abstract

We analyzed the asparagine-linked oligosaccharide chains of rat haptoglobin which were synthesized and secreted by hepatocytes in primary culture. When the cells were incubated with either [³H]mannose,[³H]galactose, or [³H]fucose, all the radioactive precursors were incorporated into the β subunit of haptoglobin. [³]HMannose-labled haptoglobin was purified from the culture medium by immunoaffinity chromatogrpahy, and [³H]oligosaccharides were prepared by strong alkali-borohydride treatment. The oligosccharides obtained were analyzed by anion-exchange high-performance liquid chromatography, concanavali-A - Sepharose chromatography and Bio-Gel P-4 chromatography before and after sequential exoglycosidase digestions. The oligosaccharides labeled with [³H]fucose or [³H]galactose were also characterized by the above methods. The results indicated that rat haptoglobin contains two complex-type oligosccharide chains in each β subunit one with a possible structure of (± NeuAc→Galβ→GlcNAcβ→)3(Manα→)2Manβ→GlcNAc→(±Fucα→)GcNAc and the other with (±NeuAc→Galβ→GlcNacβ→Manα→)2Manβ→GlcNAc→(±Fucα→)GlcNAc. [ABSTRACT FROM AUTHOR]

Published
1986
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37. Disparate effects of monensin and colchicine on intracellular processing of secretory proteins in culture rat hepatocytes.

Author

Oda, Kimimitsu, Misumi, Yoshio, and Ikehara, Yukio

Subjects
BIOSYNTHESIS, PROTEINS, ALBUMINS, LIVER cells, COLCHICINE, PACLITAXEL, GLYCOPROTEINS
Abstract

We have studied the biosynthesis and intracellular processing of three major secretory proteins, albumin, α1-protease inhibitor and α2u-globulin, in cultured rat hepatocytes. The effect of secretion-blocking agents, monensin, a monovalent ionophore, and the microtubule-affecting agents colchicine and taxol was determined. In the control cells, α1-protease inhibitor, a glycoprotein, was first synthesized as an endoglycosidase-H-sensitive form with Mr 51000, and then processed to two endoglycosidase-H-resistant forms having Mr 51000 and 56000, the latter of which was secreted into the medium. Initially synthesized proalbumin was converted with chase to serum-type albumin, while no pro-type precursor was identified for α2u-globulin. In the cells lrcated with colchicine or taxol, in which secretion was greatly inhibited, the fully processed α1-protease inhibitor and albumin accumulated and were finally secreted into the medium. In the monensin-treated cells, however, most of the newly synthesized α1-protease inhibitor and albumin were not processed to the final mature forms, resulting in accumulation of two 51000-Mr forms and proalbumin, respectively. Moreover in treated cells, proalbumin and the endoglycosidase-H-resistant α1-protease inhibitor were finally secreted into the medium. Such an effect was not caused by NH4Cl which also inhibited the secretion and is known to exert the similar effect as monensin on the receptor-mediated endocytosis pathway. Based on these results, the use of monensin may prove valuable for more detailed analysis of intracellular processing of various proteins. [ABSTRACT FROM AUTHOR]

Published
1983
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38. Biosynthesis and processing of pro-C3, a precursor of the third component of complement in rat hepatocytes: effect of secretion-blocking agents

Author

Misumi, Yoshio, Takami, Noboru, and Ikehara, Yukio

Abstract

Biosynthesis and intracellular processing of the third component (C3) of complement were studied in cultured rat hepatocytes. In the control cells, the complement C3 was synthesized as a pro-form, a single polypeptide chain comprising both the α- and β-subunits. Although the cleavage of the pro-form into the subunits was not clearly demonstrable within the cells during pulse-chase periods, all the secreted C3 was the mature processed form. The cells were treated with secretion-blocking agents with different modes of action, colchicine and monensin. Colchicine caused an accumulation of the processed C3 within the cells, whereas monensin blocked the secretion without a significant accumulation of the processed form. The results indicate that the conversion of the C3 pro-form into the subunits takes place in the secretory vesicles just before the secretion.

Published
1984
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39. Brefeldin A arrests the intracellular transport of a precursor of complement C3 before its conversion site in rat hepatocytes

Author

Oda, Kimimitsu, Hirose, Shinichi, Takami, Noboru, Misumi, Yoshio, Takatsuki, Akira, and Ikehara, Yukio

Abstract

The effects of brefeldin A on intracellular transport and posttranslational modification of complement C3 (C3) were studied in primary culture of rat hepatocytes. In the control culture C3 was synthesized as a pre‐cursor (pro‐C3), which was processed to the mature form with α‐ and β‐subunits before its discharge into the medium. In the presence of brefeldin A the secretion of C3 was strongly blocked, resulting in accumulation of pro‐C3. However, after a prolonged interval the mature form of C3 was finally secreted. The results indicate that brefeldin A impedes translocation of pro‐C3 to the Golgi complex where pro‐C3 is converted to the mature form, but not its proteolytic processing, in contrast to the effects of monensin and weakly basic amines.

Published
1987
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40. A novel Rab GTPase, Rab33B, is ubiquitously expressed and localized to the medial Golgi cisternae

Author

Zheng, Jun Ying, Koda, Toshiaki, Fujiwara, Toshiyuki, Kishi, Masahiko, Ikehara, Yukio, and Kakinuma, Mitsuaki

Abstract

Small GTP-binding proteins of the Rab family play important roles at defined steps of vesicular transport in protein secretion and the endocytosis pathway. In mammals, more than 30 proteins belonging to the Rab family have been reported to date. We report here the molecular cloning and characterization of a novel Rab protein, Rab33B. The amino acid sequence of Rab33B shows 55.3% identity to the Rab33A protein (previously called S10), and these two proteins share unique amino acid sequences at the effector domain. The genomic organization of rab33B was the same as rab33A: it consists of two exons. Thus, these two proteins make a subclass within the Rab family. Northern blot analysis showed that rab33B is expressed ubiquitously in mouse tissues, in contrast to rab33A whose expression is restricted to the brain and the immune system. A 26 kDa protein was detected by western blotting using a Rab33B-specific monoclonal antibody. Using immunofluorescence studies, Rab33B was shown to co-localize with α-mannosidase II, a Golgi-specific marker. Immunoelectron microscopy analysis further defined the localization of Rab33B to the medial Golgi cisternae. These results suggest Rab33B plays a role in intra-Golgi transport.

Published
1998
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41. Abnormal Phosphoenolpyruvate Transport in Erythrocytes of Hereditary Spherocytosis

Author

Ideguchi, Hiroshi, Hamasaki, Naotaka, and Ikehara, Yukio

Abstract

The rate of phosphoenolpyruvate transport in erythrocytes from patients with hereditary spherocytosis and from healthy individuals was examined in a 0.1 Mcitrate buffer (pH 6.1 at 37°C) containing 10 mMphosphoenolpyruvate and 10 mMNaF. The rate in erythrocytes from patients with hereditary spherocytosis was 0.09 ± 0.02 µmole/min/ml of cells (mean ± SD, n= 8), whereas the rate in erythrocytes from healthy individuals was 0.23 ± 0.03 µmole/min/ml of cells (mean ± SD, n= 8). The lower rate of transport in erythrocytes of hereditary spherocytosis could not be ascribed to a different glycolytic response to NaF or to a difference in cell age distribution. This phenomenon seemed to be a reflection of some abnormality in the erythrocyte membrane from patients with hereditary spherocytosis.

Published
1981
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