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S Kashiwamura

Publications and source records attributed to S Kashiwamura.

25 records · Page 2Linked to original sources
PubMed1990

Structure of the murine mb-1 gene encoding a putative sIgM-associated molecule.

Genomic DNA clones containing the B cell-specific murine mb-1 gene were isolated and a 5.6-kb BamH I fragment was characterized. It is 5629 bp long and contains five exons: an exon containing the 5' untranslated and the coding sequence of the signal peptide, an exon of 294 bp, which contains most of the extracellular sequence of the MB-1 protein, a 119-bp long exon coding mainly for the transmembrane portion, and two exons of 69 bp and 427 bp encoding the cytoplasmic domain and the 3'-untranslated region, respectively. The mb-1 gene does not contain a "TATA box" found in many eukaryotic promoters. The 5'-flanking region has sequence stretches homologous to IgVH 5'-promoter regions and a bcl 2 intron sequence. It contains the decanucleotide sequence (ATGGCAAATA) almost identical to the octamer motif of IgVH promoters. A B cell-specific DNase I-hypersensitive site was found in the 3'-flanking region indicating that this region might be involved in B cell-specific expression of mb-1. Southern blot analysis of genomic liver DNA with the cloned mb-1 cDNA suggests the existence of another mb-1-related gene segment.

Amino Acid Sequence↗
PubMed1988

B lymphocyte lineage-restricted expression of mb-1, a gene with CD3-like structural properties.

A gene, called m-mb-1, was isolated from a murine pre-B-minus T lymphocyte subtracted library. It was found expressed as mRNA at low to medium abundance in early progenitors of the B lineage, in pre-B and mature B lineage cell lines, in normal resting B lymphocytes and in polyclonally activated B cell blasts. The gene was not expressed in plasmacytomas, in cell lines of the monocyte/macrophage, the T lymphocyte or the fibroblast lineages, nor in thymus, liver, heart, kidney, lung or brain. The nucleotide sequence of the m-mb-1 gene encodes a putative membrane glycoprotein with 220 amino acids, which includes a leader sequence, a putative extracellular domain with two potential N-glycosylation sites, a transmembrane portion and a putative intracellular domain. The partial sequence of a human homologue, h-mb-1, shows nearly 90% homology in nucleotide as well as amino acid sequences to the murine form of a stretch of the putative intracytoplasmic domain. Antibodies raised against a fusion protein of m-mb-1 with protein A, affinity purified for their m-mb-1 specificity, stained pre-B and mature B cell lines on their surface, but did not stain T cell lines and fibroblasts. Antibodies raised against a stretch of 20 amino acids of the putative intracellular domain with 90% homology between the mouse and human protein did not stain the surface of any cell lines tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1985

Purification to homogeneity and characterization of human B-cell differentiation factor (BCDF or BSFp-2).

Human B-cell differentiation factor (BCDF) was purified to homogeneity by sequential filtration and chromatography of culture supernatants from TCL-Na1 cells on an AcA34 gel column and then on a Mono P column with fast protein liquid chromatography and reversed-phase HPLC. A 5300-fold enrichment in specific activity of BCDF with about 25% recovery was attained. The homogeneity of purified BCDF was evidenced by the following: (i) the specific activity was 1.7 X 10(7) units/mg of protein, (ii) only two bands, Mr 19,000 and 21,000, were identified by NaDodSO4/PAGE under reduced as well as nonreduced conditions, and (iii) BCDF activity was recovered from the gel after NaDodSO4/PAGE in the fractions corresponding to protein bands of Mr 19,000 or 21,000. Purified BCDF induced Ig secretion in Epstein-Barr virus-transformed cell lines; as little as 3 pM gave 50% of the maximum reaction achieved by 30-80 pM BCDF. Purified BCDF induced Ig production in activated B cells without any effect on cell growth. Purified BCDF did not show any activity of interleukin 1 or 2, B-cell stimulatory factor (BSF)p-1, B-cell growth factor II (BCGF-II), or interferon. Since BCDF was isolated and characterized as described, we propose that the BCDF that induces the final differentiation of B cells into high-rate Ig-secreting cells be designated BSFp-2.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1982

A T15-idiotype-positive T suppressor hybridoma does not use the T15 VH gene segment.

The T suppressive factor (TsF) released from a T15-idiotype-positive phosphocholine (PCho)-specific T hybridoma, F18-3-4, which was formed by fusion between BALB/c T cells and BW5147 thymoma, was immunochemically characterized. TsF inhibited the in vitro induction of both IgE and IgG1 antibody responses of 2,4-dinitrophenyl keyhole limpet hemocyanin (DNP-KLH)-primed spleen cells in the presence of PCho-KLH-DNP. TsF had the ability to bind to PCho determinants and possessed T15 idiotype determinants as well as Iad products. However, we were unable to detect either the rearrangement of the T15 VH gene or the presence of T15 VH gene transcripts in hybridomas by DNA and RNA blot hybridization analyses with the T15 VH DNA probe.

Animals↗
PubMedDate not supplied

Functional expression of a microinjected Ed alpha gene in C57BL/6 transgenic mice.

The class II major histocompatibility antigens, I-A and I-E, have been detected on the surface of certain immunocompetent cells, including B lymphocytes and monocytes. These molecules are involved in cell-cell interactions in the immune responses. Each class II antigen consists of two subunits, alpha and beta chains, and the genes encoding these subunits have been well characterized at the molecular level. To analyse the regulatory mechanism of E alpha gene expression and the role of the I-E antigen in the regulation of the immune responses, we have produced transgenic mice by microinjecting cloned Ed alpha genes into fertilized eggs of C57BL/6 mice of b haplotype. This strain of mouse carries a deletion in the upstream (5') region of the E alpha gene covering the transcriptional promoter and, therefore, does not express this gene. Interestingly, this genetic defect of the E alpha gene is accompanied by the inability of the host mouse to respond to a certain set of antigens, phenomena generally termed Ir gene control. We report here that the Ed alpha genes are expressed in these transgenic mice to form the I-Ed alpha Eb beta antigen on the surface of B lymphocytes and monocytes and that these I-E antigens are functional in terms of the induction of a mixed lymphocyte reaction and the restoration of immune responsiveness to poly(L-glutamic acid-L-lysine-L-phenylalanine) (GL-Phe).

Animals↗
PubMedDate not supplied

Complementary DNA for a novel human interleukin (BSF-2) that induces B lymphocytes to produce immunoglobulin.

When stimulated with antigen, B cells are influenced by T cells to proliferate and differentiate into antibody-forming cells. Since it was reported that soluble factors could replace certain functions of helper T cells in the antibody response, several different kinds of lymphokines and monokines have been reported in B-cell growth and differentiation. Among these, human B-cell differentiation factor (BCDF or BSF-2) has been shown to induce the final maturation of B cells into immunoglobulin-secreting cells. BSF-2 was purified to homogeneity and its partial NH2-terminal amino-acid sequence was determined. These studies indicated that BSF-2 is functionally and structurally unlike other known proteins. Here, we report the molecular cloning, structural analysis and functional expression of the cDNA encoding human BSF-2. The primary sequence of BSF-2 deduced from the cDNA reveals that BSF-2 is a novel interleukin consisting of 184 amino acids.

Amino Acid Sequence↗