Search PubMed⌕ Search

Biomedical subjects

T Nikaido

Publications and source records attributed to T Nikaido.

At least 199 records · Page 11Linked to original sources
PubMed1985

Nucleotide sequence of mouse IL-2 receptor cDNA and its comparison with the human IL-2 receptor sequence.

We have cloned cDNA encoding the mouse interleukin-2 (IL-2) receptor from a murine T cell line, CTLL using human IL-2 receptor cDNA as probe. COS 7 cells transfected with the cDNA expressed the antigen recognized by the monoclonal antibody against the murine IL-2 receptor. The cDNA identified 4 species of mRNA (4.5, 3.5, 2.2 and 1.5 kb) of the mouse IL-2 receptor in CTLL cells. Difference in the length of mRNA seems to be ascribed to the variable length of the 3' untranslated sequence. Total nucleotide sequence (approximately 1400 bp) of this cDNA was determined and compared with the human receptor. The nucleotide and amino acid sequences of the IL-2 receptor are 70% and 60%, respectively, homologous in average between the two species. The comparison has revealed several conserved regions localized to particular exons such as transmembrane and cytoplasmic portions, suggesting that these regions are important for receptor function and its regulation.

Amino Acid Sequence↗
PubMed1985

TCGF (IL 2)-receptor inducing factor(s). I. Regulation of IL 2 receptor on a natural killer-like cell line (YT cells).

A continuous cell line (YT cells) with inducible receptor for T cell growth factor (TCGF)/interleukin 2 (IL 2) was established from a 15-yr-old boy with acute lymphoblastic lymphoma and thymoma. YT cells were tetraploid, having 4q+ chromosomal markers, and proliferated continuously in vitro without conditioned medium (CM) or IL 2. They were weakly positive for OKT9, OKT11, and Tac antigen (Ag), a determinant closely associated with the receptor for IL 2 (IL 2-R), and were negative for OKT1, OKT3, OKT4, and OKT8 Ag. YT cells also expressed HNK-1 Ag and Fc receptors for IgG, which are expressed on natural killer (NK) cells. They retained a killing activity against human cell lines, including K562 (myeloid), T, and B cell lines. Unlike Tac Ag/IL 2-R(+) cell lines derived from adult T cell leukemia (ATL), YT cells were negative for HTLV, as proved by Southern blotting with cDNA for viral DNA. The expression of Tac Ag was markedly enhanced in 18 hr, when YT cells were incubated with CM from PHA-stimulated peripheral blood leukocytes (PBL) or spleen cells, as determined by immunofluorescence by using flow cytometry and binding assay with 125I-anti-Tac antibody (Ab). The binding study with 125I-labeled recombinant IL 2 showed 3.2 X 10(4) IL 2 receptor sites on YT cells precultured with CM. PHA-P and Con A neither agglutinate nor enhance the expression of IL 2-R/Tac antigen on these non-T cell line cells. Furthermore, neither recombinant IL 2 nor gamma-interferon could induce IL 2-R on YT cells, suggesting the presence of a unique IL 2-R inducing factor in PBL or spleen CM. Unlike Tac Ag on HTLV(+), ATL-derived cell lines (Hut-102, MT-1, ATL-2), the expression of Tac Ag on YT cells was down-regulated by anti-Tac Ab. The induction of Tac Ag/IL 2-R on YT cells seemed specific, because the enhancement of Tac Ag expression was not associated with that of Ia Ag and T9/transferrin receptor.

Adolescent↗
PubMed1985

Adult T leukemia cells produce a lymphokine that augments interleukin 2 receptor expression.

Human T-cell leukemia virus (HTLV)-infected cell lines derived from adult T-cell leukemia (ATL) express constitutively the receptor for Interleukin-2 (IL-2-R) and the associated antigen (Tac antigen). In contrast, the same antigen is transiently expressed by normal T-cells only after immune stimulation. Recently, it was reported that the constitutively expressed Tac antigen on ATL cells and cell lines was not down-regulated or modulated by anti-Tac antibody. Since the antigen was modulated on normal mitogen- or alloantigen-stimulated T-cells, we postulated that the regulation of IL-2-R may be abnormal on ATL cells; the synthesis of IL-2-R is continuously stimulated in these cells. A unique HTLV/ATLV(-) cell line (YT) derived from a child with acute lymphoblastic leukemia was found to express low levels of Tac antigen that could be enhanced by various stimuli, including conditioned medium (CM) derived from normal lymphocytes, but not by lectins (PHA, Con A). Of particular interest, the exposure of YT cells to CM from ATL cell lines with helper phenotype revealed the presence of factor(s) (ATL-derived factor, ADF) that augmented the synthesis and expression of IL-2-R/Tac antigen on YT cells and promoted YT cell growth. CM from HTLV(-) leukemia cell lines lacked both IL-2-R augmenting activity and a growth promoting activity. Immunoaffinity-purified IL-2 and recombinant gamma interferon also lacked IL-2-R augmenting activity. Moreover, the physicochemical analysis with Fast protein liquid chromatography (FPLC) revealed that ADF was quite different in pI point from the IL-2-R augmenting activity in CM from normal lymphocytes. These results suggested that ADF is a unique product of HTLV(+) cells. The possible relationship between ADF production, HTLV infection, and the abnormal expression of IL-2-R is suggested, and these abnormalities may be advantageous for the leukemogenesis and abnormal growth of ATL.

Adolescent↗
PubMed1983

Mutation of the N-acetylmuramyl-L-alanine amidase gene of Escherichia coli K-12.

Mutants of Escherichia coli with very low N-acetylmuramyl-L-alanine amidase activity were isolated. The gene amiA responsible for most of this enzyme activity was mapped at 51 min on the E. coli chromosome, with the most plausible gene order assumed to be amiA pts(H or I) purC. The mutant phenotype was recessive and physiologically undiscernible.

Amidohydrolases↗
PubMed1982

Nucleotide sequences of switch regions of immunoglobulin C epsilon and C gamma genes and their comparison.

Immunoglobulin class switch involves a unique recombination event that takes place at the switch (S) region which is located 5' to each constant region (C) gene of the heavy (H) chain. For example, differentiation of the B lymphocyte from a mu-chain producer to an epsilon-chain producer is mediated by the switch recombination between the S mu and S epsilon regions. In order to elucidate the molecular mechanism for the switch recombination, we have determined nucleotide sequences surrounding the class switch recombination sites of the C epsilon and C gamma 3 genes and those in the 5' flanking regions of the C gamma 2a and C delta genes. The results indicate that the 5' flanking regions of all the CH genes except for the C delta gene contain the S regions which comprise tandem repetition of short unit sequences in agreement with the previous analyses of the S gamma 1, S gamma 2b, S mu, and S alpha regions. Comparison of the nucleotide sequences of all the S regions revealed that length as well as nucleotide sequences of the S regions vary among different classes of the CH gene, but they share short common sequences, (G)AGCT and TGGG(G). The nucleotide sequence of the S mu region is homologous to those of the other S regions in the decreasing order of the S epsilon, S alpha, S gamma 3, and (S gamma 1, S gamma 2b, s gamma 2a) regions. We have compared the nucleotide sequences immediately adjacent to the recombination sites of seven rearranged genes and have always fund tetranucleotides TGAG and/or TGGG, except for one case. Such tetranucleotides may constitute a part of the recognition sequence of a putative recombinase. These results provide further support for our previous proposal that the switch recombination may be facilitated by short common sequences dispersed in all the S regions.

Animals↗
PubMed1982

Structure of human immunoglobulin gamma genes: implications for evolution of a gene family.

We have cloned five human immunoglobulin gamma genes from a fetal liver gene library. Four of them encode the known human immunoglobulin gamma chains gamma 1, gamma 2, gamma 3 and gamma 4. A fifth gamma gene seems to be a pseudogene. Nucleotide sequence determination demonstrates that the gamma 3 gene contains four separate hinge exons. Comparison of these hinge exons with those of the other gamma genes indicates that the first hinge exon is homologous to that of the pseudogene, and that the other three hinge exons are homologous to that of the gamma 1 gene, suggesting that the gamma 3 gene ancestor is a hybrid gene created by unequal crossing-over between the ancestral gamma 1 and psi gamma genes. Amplification of the gamma 1-type hinge exon probably followed to complete the gamma 3 gene. This hypothesis inevitably postulates the gene order 5'-gamma 1-gamma 3-psi gamma-3'. Cloning of overlapping chromosomal segments demonstrates that the gamma 2 gene is located 19 kb 5' to the gamma 4 gene. These analyses indicate that the human gamma-gene family has evolved by several types of DNA rearrangemet, including duplication of a complete gene; duplication of a hinge exon; and reassortment of exons by unequal cross-over between two adjacent genes.

Animals↗