Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley-VCH Verlag  

Signaling events leading to B cell growth or apoptosis are beginning to be unravelled, but detailed information is still lacking. To identify signaling molecules involved in B cell antigen receptor (BCR)-initiated pathways, we used the immature B cell line, WEHI-231, to investigate protein tyrosine phosphatases (PTP) whose expression was modulated by BCR ligation. Among the PTP cloned by reverse transcription-PCR, mRNA expression of the proline-, glutamic acid-, serine- and threonine-rich (PEST) domain phosphatase (PEP) was selectively elevated 3.1-fold within 3 h after anti-IgM antibody stimulation. In contrast, expression of another PEST domain phosphatase, PTP-PEST, was unaffected. Western blot analysis revealed that 71% of PEP was located in the cytosolic fraction, while 29% was in the membrane fraction. To examine the direct contribution made by PEP to BCR-initiated signal transduction, we transfected an antisense PEP cDNA into WEHI-231 cells. Two stable clones were established in which PEP expression was reduced by 34% and 47%, respectively. Strikingly, BCR-mediated inhibition of DNA synthesis was significantly rescued in the clones, and G1 phase cell cycle arrest and apoptosis were almost completely ablated. Considered collectively, these results indicate that PEP is a positive, crucial regulator in determining B cell fate triggered by BCR engagement.

DOI： 10.1002/(SICI)1521-4141(199903)29:03<887::AID-IMMU887>3.0.CO;2-9

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Language：English   Publishing type：Research paper (scientific journal)  

Role of CD45 in B cell antigen receptor (BcR)‐mediated signaling events in mature B cells was examined using BAL‐17 and its CD45‐negative clones. In the CD45‐negative clones, BcR stimulation induced tyrosine phosphorylation almost identical to the parental cells, with a few exceptions of reduced phosphorylation, especially of a protein of about 60 kDa. BcR‐induced calcium responses were reduced in the CD45‐negative clones, but the kinetics were similar to the parent. BcR stimulation led to growth inhibition in the parental cells, but signals for growth inhibition were completely blocked in the CD45‐negative clones. Interestingly, the same stimulation induced low, but significant levels of apoptosis both in the parent and in the CD45‐negative clones. Thus, in mature BAL‐17 cells, CD45 subtly mediates early signaling events (tyrosine phosphorylation and Ca2+ mobilization), and is absolutely required for the signaling pathway leading to growth regulation, but has limited effects on apoptosis. Copyright © 1995 WILEY‐VCH Verlag GmbH &amp
Co. KGaA, Weinheim

DOI： 10.1002/eji.1830250823

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Non-malignant rat liver epithelial cell line BRL was reported to adhere to a substrate by fibronectin. DNA synthesis of these cells was induced by adhesion to a substrate by fibronectin, while DNA synthesis in non-adhered cells was not observed. These results indicated that DNA synthesis in BRL cells is inducible by the cell adhesion signaling. Adhesion-inducible DNA synthesis was strongly inhibited by Herbimycin A. In contrast, vanadate showed the tendency to promote adhesion-inducible DNA synthesis. These results suggest that DNA synthesis caused by the cell adhesion in these cells was regulated by both phosphorylation and dephosphorylation at tyrosine residue. © 1995 by Academic Press, Inc.

DOI： 10.1006/bbrc.1995.2365

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Language：Japanese   Publishing type：Research paper (other academic)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press  

We prepared phospho-tyrosyl glutamine synthetase (P-GS) with suppressed activity from a highly adenylylated glutamine synthetase and applied it to the assay of protein-tyrosine phosphatase (PTPase) present in non-malignant rat liver cells (BRL) by RSV-transformation. The maximum PTPase activity toward P-GS was observed at neutral pH (pH 7.5-8.0) in the soluble and particulate fractions prepared from both BRL and RSV-transformed (RSV-BRL) cells. At low activity levels (&lt
about 0.3 U), the PTPase activity in each fraction was proportional to the sample protein concentration (A280) and the specific activity of PTPase in the soluble fraction of BRL cells was about twofold higher than that in the soluble fraction of BRL cells, while those in particulate fractions of BRL and RSV-BRL cells were almost the same as each other. Soluble fractions of BRL and RSV-BRL were subjected to molecular-sieve and anion-exchange chromatographies. One major PTPase activity, with an Mr of about 40, 000 (40k), was detected in the BRL soluble fraction, and two were detected in the RSV-BRL soluble fraction with Mrs of about 40k and 60k. The 40k PTPases in BRL and RSV-BRL had the same profiles on anion-exchange chromatography, but the 60k PTPase in RSV-BRL cells showed a different profile. We suggest that the RSV-transformation of BRL cells induced the appearance of the 60k PTPase in the soluble fraction. © 1994 BY THE JOURNAL OF BIOCHEMISTRY.

DOI： 10.1093/oxfordjournals.jbchem.a124338

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (other academic)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (other academic)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press  

It was previously found that rabbit serum contains a growth-inhibitory substance for a tumorigenic rat liver cell line RSV-BRL. In the present study, the growth inhibitor was purified from normal rabbit serum to show a homogeneous protein band with a molecular weight (Mr) of 56 k on SDS-polyacrylamide gel electrophoresis under non-reducing conditions. The purified growth inhibitor, tentatively named rabbit serum-derived growth inhibitor (RSGI), potently inhibited the growth of RSV-BRL and nine kinds of other cell lines including three human tumor cell lines at a concentration of 20 ng/ml or higher. The growth-inhibitory effect of RSGI was reversible and appeared to be cytostatic rather than cytotoxic. RSGI was stable to heating at 56°C for 30 min or treatment with 0.1 M 2-mercaptoethanol, but labile to heating at 100°C for 3 min or treatment with 1 M acetic acid (pH 2.3), 6 M urea, 50% (v/v) 1-propanol, or 0.1% (w/v) trypsin. These properties of RSGI suggested that it was different from type β transforming growth factors, tumor necrosis factor-α, and other known growth-regulatory factors. © 1991 by The Journal of Biochemistry.

DOI： 10.1093/oxfordjournals.jbchem.a123597

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Language：Japanese   Publishing type：Research paper (other academic)  

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Language：English   Publishing type：Research paper (scientific journal)  

A cDNA library constructed from poly(A)+ RNA isolated from Dictyostelium discoideum cells at 12 h of development was screened with the hamster elongation factor 2 (EF-2) cDNA. Several different cDNA clones which hybridized were isolated after a second screening. A cDNA clone representing the 5'-end of the mRNA was obtained by primer extension. By comparing the amino acid sequence deduced from the nucleotide sequences of these clones with that of hamster EF-2, we found enough homology between them to conclude that the isolated clones were complementary to the mRNA of D. discoideum EF-2. The N terminus which is the GTP-binding domain and the C-terminal half where it interacts with a ribosome showed a high degree of homology. The amino acid sequence of the carboxyl half includes that it contain a site of ADP-ribosylation by diphtheria toxin. From the Northern blotting analysis, the size of the mRNA was estimaed to be 2.6 kilobases. The expression of the mRNA was high in vegetative cells, became maximal at the aggregation stage, and decreased thereafter through development. Upon differentiation of prespore and prestalk cells, the mRNA was highly enriched in the former over the latter. ADP-ribosylation assay of EF-2 protein by diphtheria toxin showed nearly the same developmental changes for the protein as the mRNA. However, prestalk cells were found to contain the same amount of the protein as prespore cells. The Southern blot analyses indicated that the gene encoding EF-2 is unique.

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Language：Japanese   Publishing type：Part of collection (book)  

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press  

It was found that a non-tumorigenic epithelial cell line from the liver of a Buffalo-strain rat (BRL) secreted into the culture medium various inhibitors of the growth of BRL and RSV-BRL (tumorigenic BRL transformed by infection of Rous sarcoma virus). The secreted inhibitors were classified into two types: one inhibited the growth of BRL to a greater extent than that of RSV-BRL (non-tumorigenic BRL growth inhibitor, NGI), and the other, vice versa (tumorigenic BRL growth inhibitor, TGI). Two NGI (NGI-I and NGI-II) and two TGI (TGI-I and TGI-II) were highly purified from the serum-free conditioned medium. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis without 2-mercaptoethanol, NGI-I and II gave protein bands with molecular weights (Mr) of 56,000 and 21,000, respectively. TGI-I and II gave a band that migrated faster than bromophenol blue marker dye, but they did not pass through an ultrafiltration membrane with an Mr cutoff of 5,000. In the presence of a reducing reagent, only NGI-II showed a decrease of Mr, from 21,000 to 11,000. NGI and TGI showed 50% growth inhibition with BRL and RSV-BRL, respectively, at 5-15 ng/ml in the medium containing 10% fetal calf serum. NGI and TGI all were stable to 1 M acetic acid (pH 2.3) and 6 M urea, but labile to 5 mM dithiothreitol or trypsin. Of the eight cell lines tested, NGI-I was most effective on BRL, NGI-II on BRL and HSC-3 (human tongue squamous carcinoma), and both TGI-I and II on RSV-BRL. © 1988 BY THE JOURNAL OF BIOCHEMISTRY.

DOI： 10.1093/oxfordjournals.jbchem.a122373

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE BIOCHEMICAL SOC  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

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Language：English   Publishing type：Research paper (other academic)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press  

We previously reported that sera from various kinds of animals contain a protein(s) capable of inhibiting the growth of the non-malignant epithelial cell line derived from Buffalo rat liver (BRL). In the present study, a similar epithelial cell-specific growth inhibitor (EGI) was purified to homogeneity from an acid-ethanol extract of human platelets. During purification, EGI was separated from the major component of type β transforming growth factor (TGF-β), which can stimulate the colony formation of the non-malignant fibroblastic cell line derived from rat kidney (NRK) in soft agar in the presence of epidermal growth factor (EGF). The purified EGI had an Mr of 27,000, and was composed of two subunits identical in Mr. It significantly inhibited the growth in monolayer cultures of three non-malignant epithelial cell lines, BRL, MDCK (from Madin-Darby canine kidney) and BSC-1 (from African green monkey kidney), at doses lower than 40 pg/ml in medium containing 10% fetal calf serum. Its inhibitory activity was stable against heating at 90°C for 3min, but not against treatment with 50 mM dithiothreitol. In addition, TGF-β was also partially purified from the same extract. The purified TGF-β did not show any inhibitory activity toward the growth of BRL, MDCK, BSC-1, or NRK. © 1986, by the Japanese Biochemical Society.

DOI： 10.1093/oxfordjournals.jbchem.a121761

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Publisher：1  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC IN VITRO BIOLOGY  

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Language：Japanese   Publishing type：Research paper (other academic)  

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Language：Japanese   Publishing type：Research paper (other academic)  

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