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M Takiguchi

Publications and source records attributed to M Takiguchi.

At least 253 records · Page 14Linked to original sources
PubMed1989

Evolutionary aspects of urea cycle enzyme genes.

The functions and expression pattern of urea cycle enzymes have undergone considerable changes during the course of evolution. Sequence analyses shows that urea cycle enzymes from mammals are homologous to microbial enzymes of the arginine-metabolic pathway. Recently, an unexpected relationship was found between argininosuccinate lyase (EC 4.3.2.1), the fourth enzyme of the cycle, and delta-crystallin, a lens structural protein of birds and reptiles.

Animals↗
PubMed1989

Tissue- and developmental stage-specific expression of the rat ornithine carbamoyltransferase gene in transgenic mice.

Rat ornithine carbamoyltransferase (OCT; EC 2.1.3.3) is encoded by a large gene of 75 kilobases. Expression of this gene is restricted to the liver and small intestine, and there is an increase in expression late in gestation. The recombinant gene carrying 1.3 kilobases of the 5' flanking region of the gene fused to the rat OCT cDNA was microinjected into fertilized eggs, and 17 transgenic mice were produced. Expression in the liver of the transgene was detected in three mice. In these mice, the transgene expression was observed exclusively in the liver and small intestine. Expression of the transgene in the intestine was comparable to that of the endogenous mouse OCT gene, whereas expression in the liver was much lower than that of the endogenous gene. The developmental pattern of expression of the transgene was similar to that of the endogenous gene. Therefore, the 5' flanking sequence of the rat OCT gene seems to be sufficient for the developmental and tissue-specific expression of the gene. An explanation for low expression in the liver remains the subject of ongoing study.

Animals↗
PubMed1989

Allo-class I-reactive CD4-CD8- T cell hybridomas recognize the conformational change of class I molecule resulting from the exchange of the alpha 3 domain.

H-2Kb-reactive, interleukin (IL) 2-producing T cell hybridomas possessing neither CD8 nor CD4 molecules were employed for the study of allorecognition on interspecies hybrid antigens by T cells in the absence of an influence of these accessory molecules. Both HTB176.10 and HTB177.2 T cell hybridomas reacted with KbKbB7 hybrid antigens as well as Kb antigens and they produced more IL2 in response to Kb antigens than KbKbB7 hybrid antigens. IL2 production of these T cell hybridomas was dependent on the surface expression level of Kb molecules on stimulators. Therefore, L cells expressing almost equivalent levels of Kb or hybrid antigens were selected for further functional studies by these T cell hybridomas. They apparently produced less IL2 in response not only to interspecies hybrid antigens but also to interspecies hybrid antigens in response to Kb antigens. These results indicated that T cell hybridomas recognized the conformational change of class I molecule resulting from the exchange of the alpha 3 domain via their T cell receptors.

Amino Acid Sequence↗
PubMed1989

The structure of HLA-B35 suggests that it is derived from HLA-Bw58 by two genetic mechanisms.

The primary structure of HLA-B51 and HLA-Bw52 suggested that HLA-B51 was derived from HLA-Bw52 by the combination of a genetic exchange with HLA-B8 and a point mutation. To investigate the evolution of the HLA-B5 cross reactive group, the HLA-B35 gene was cloned and the primary structure was determined. HLA-B35 is identical to HLA-Bw58 except in the alpha 1 domain. The alpha 1 domain of HLA-B35 except Bw4/Bw6-associated amino acids is identical to that of HLA-B51, which was suspected to be an intermediate gene between HLA-B51 and HLA-Bw52. These data suggest that HLA-B35 has evolved from HLA-Bw58 in two steps; an in vivo replacement of the alpha 1 domain with HLA-B51 and genetic exchange with one of the HLA-Bw6 genes. These three genes and HLA-Bw58 are postulated to share a common ancestor. As HLA class I molecules of a serologically cross-reactive group (CREG) have limited polymorphism, we suspected they might have evolved from a common ancestor. In fact, the structures of HLA-B51 and HLA-Bw52 in HLA-B5 CREG demonstrate that they differ by only two amino acids. Both substitutions are in the helical region of the alpha 1 domain and suggest that HLA-B51 could be derived from HLA-Bw52 by the combination of a genetic exchange with HLA-B8 and a point mutation (Hayashi et al. 1989). HLA-B35 belongs to the HLA-B5 CREG and is serologically related to Bw6, while HLA-B5 (B51 and Bw52) is related to Bw4. HLA-B35 is serologically closer to HLA-B51 than to HLA-Bw52. Therefore, we have cloned a genomic gene of HLA-B35 and determined its structure to study further the evolution of the HLA-B5 family.

Amino Acid Sequence↗
PubMed1989

Structure of the rat argininosuccinate lyase gene: close similarity to chicken delta-crystallin genes.

Argininosuccinate lyase (EC 4.3.2.1) is an enzyme of arginine biosynthesis and is also involved in the urea cycle in the liver of ureotelic animals. A comparison of cDNA-derived amino acid sequences revealed that argininosuccinate lyase is highly homologous with chicken delta-crystallin, a major structural protein of the eye lens. The gene for the rat argininosuccinate lyase was cloned and its structure was determined. This gene is a single-copy gene about 14 kilobases long and is split into 16 exons. A comparison with chicken delta-crystallin genes revealed that all introns interrupt the protein-coding regions at homologous positions. This close similarity in structural organization provides strong evidence for the view of Piatigorsky et al. [Piatigorsky, J., O'Brien, W. E., Norman, B. L., Kalmuck, K., Wistow, G., Borras, T., Nickerson, J. M. & Wawrousek, E. F. (1988) Proc. Natl. Acad. Sci. USA 85, 3479-3483] that chicken delta 1- and delta 2-crystallin genes evolved by recruitment and duplication of the preexisting argininosuccinate lyase gene and that delta 2-crystallin is probably the direct homologue argininosuccinate lyase.

Amino Acid Sequence↗
PubMed1989

Analysis of xenoantigenicity of HLA class I molecules by a complete series of human-mouse hybrid genes.

To investigate the xenoantigenicity of HLA class I antigens, a complete series of human/mouse chimeric major histocompatibility complex class I genes was constructed by using the human HLA-B7 and mouse H-2Kb genes. All of these hybrid antigens were stably expressed on L cells at high levels. Nine anti-HLA class I monoclonal antibodies, including 5 monomorphic, 3 broad polymorphic, and 2 specific polymorphic ones, were tested by binding to these cell lines. Our data suggest that the alpha 2 domain of HLA-B7 plays an important role in the formation of the antigenic determinants recognized by all of the anti-HLA class I mAbs tested. However, the antigenic determinants of the monomorphic mAbs were complex. In some cases, all of the three extracellular domains were required for expression of the epitope. The location of xenoimmunogenic site of HLA-B7 antigen was also examined by immunizing (B6xC3H)F1 and C3H mice with the parental and hybrid antigens. Our data suggest that the alpha 1 and alpha 2 domains of HLA-B7 must be expressed together for production of antibodies against monomorphic determinants of HLA class I antigens, while the alpha 3 alone can induce xenoantibodies in (B6xC3H)F1 mice but not in C3H mice.

Animals↗
PubMed1988

Reconstitution of mitochondrial protein transport with purified ornithine carbamoyltransferase precursor expressed in Escherichia coli.

Ornithine carbamoyltransferase (OTC; subunit, 36,000 Da) is initially synthesized as a precursor (pOTC) with a transient NH2-terminal presequence of 32 amino acid residues and imported posttranslationally into the mitochondrial matrix. The rat pOTC was synthesized in Escherichia coli using an expression vector containing a thermoinducible lambda pL promoter. The recombinant pOTC represented 5-10% of the total bacterial protein and was present in the precipitate of the disrupted bacteria. The precipitate was washed and pOTC was extracted with 8 M urea or 0.1% cetyltrimethylammonium bromide. The extracted pOTC was essentially homogeneous, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified pOTC was cleaved to the intermediate-sized product of 37,000 Da by a processing protease partially purified from the matrix fraction of rat liver mitochondria. The purified recombinant pOTC, but not the mature form of OTC synthesized in E. coli and purified, competed with the in vitro-synthesized, radiolabeled pOTC for uptake and processing by the isolated rat liver mitochondria. The radiolabeled and purified recombinant pOTC could be imported into the isolated mitochondria and processed to the mature form in an energy- and rabbit reticulocyte lysate-dependent manner. When the purified pOTC was subjected to sucrose gradient centrifugation, it sedimented as a large aggregate of greater than 60 S in the absence of reticulocyte lysate, whereas it sedimented as a complex of about 5 S in the presence of the lysate. These observations together with our previous results indicate that a protein factor(s) present in the lysate interacts with pOTC and holds it in an import-competent form.

Animals↗
PubMed1988

A noncleavable signal for mitochondrial import of 3-oxoacyl-CoA thiolase.

Rat 3-oxoacyl-CoA thiolase, an enzyme of the fatty acid beta-oxidation cycle, is located in the mitochondrial matrix. Unlike most mitochondrial matrix proteins, the thiolase is synthesized with no transient presequence and possesses information for mitochondrial targeting and import in the mature protein of 397 amino acid residues. cDNA sequences encoding various portions of the thiolase were fused in frame to the cDNA encoding the mature portion of rat ornithine transcarbamylase (lacking its own presequence). The fusion genes were transfected into COS cells, and subcellular localization of the fusion proteins was analyzed by cell fractionation with digitonin. When the mature portion of ornithine transcarbamylase was expressed, it was recovered in the soluble fraction. On the other hand, the fusion proteins containing the NH2-terminal 392, 161, or 61 amino acid residues of the thiolase were recovered in the particulate fraction, whereas the fusion protein containing the COOH-terminal 331 residues (residues 62-392) was recovered in the soluble fraction. Enzyme immunocytochemical and immunoelectron microscopic analyses using an anti-ornithine transcarbamylase antibody showed mitochondrial localization of the fusion proteins containing the NH2-terminal portions of the thiolase. These results indicate that the NH2-terminal 61 amino acids of rat 3-oxoacyl-CoA thiolase function as a noncleavable signal for mitochondrial targeting and import of this enzyme protein. Pulse-chase experiments showed that the ornithine transcarbamylase precursor and the thiolase traveled from the cytosol to the mitochondria with half-lives of less than 5 min, whereas the three fusion proteins traveled with half-lives of 10-15 min. Interestingly, in the cells expressing the fusion proteins, the mitochondria showed abnormal shapes and were filled with immunogold-positive crystalloid structures.

Acetyl-CoA C-Acyltransferase↗
PubMed1988

Human liver-type arginase gene: structure of the gene and analysis of the promoter region.

The gene for human liver-type arginase (EC 3.5.3.1), a urea cycle enzyme, was cloned and the structure was determined. This gene is 11.5 kilobases long and is split into 8 exons. The cap site was determined by nuclease S1 mapping and primer extension. A "TATA box"-like sequence is located 28 bases upstream from the cap site, and a sequence similar to the binding sites of the transcription factor CTF/NF1, a "CAAT box"-binding protein, is located 72 bases upstream. In the 5' end region, sequences resembling the glucocorticoid responsive elements, the cAMP responsive elements, and the enhancer core sequences are present. The immediately 5' flanking region of the human gene up to position -105 is 84% identical with the corresponding segment of the rat gene. In this region of the human gene, one DNase I-protected area and several hypersensitive cleavage sites were detected by footprint analysis, using nuclear extracts from the rat liver. The protected area contains the sequence similar to the binding sites of CTF/NF1 and also overlaps with the sequence resembling the glucocorticoid responsive elements.

Amino Acid Sequence↗
PubMed1988

Structural organization of the gene for rat liver-type arginase.

Liver-type arginase (EC 3.5.3.1) catalyzes the last step of urea synthesis and is expressed specifically in the liver of ureotelic animals. Expression of liver arginase is developmentally and hormonally regulated in coordination with other urea cycle enzymes. The gene for the rat enzyme was cloned and the structure determined. This gene is 12 kilobases long and is split into eight exons. All of the splice donor and acceptor sites conform to the GT/AG rule. The transcription initiation site was determined by nuclease S1 mapping and primer extension. A "TATA box"-like sequence and a "CAAT box"-like sequence are present 27 and 60 bases upstream from the cap site, respectively. Upstream and downstream from the cap site, there are several sets of direct repeats and inverted repeats and several sequences resembling the transcription factor Sp1 binding sites, the enhancer core sequences, the glucocorticoid receptor binding sites, the 12-O-tetradecanoylphorbol-13-acetate responsive elements, and the putative elements for liver-specific expression of albumin genes. A 15-nucleotide sequence in the 5'-flanking region of the arginase gene is highly homologous with sequences in the 5'-flanking regions of the genes for rat ornithine carbamoyltransferase (EC 2.1.3.3) and for human argininosuccinate synthetase (EC 6.3.4.5), other two enzymes of the urea cycle.

Animals↗
PubMed1988

Ontogeny and function of B220+ L3T4+ T-cell subset of MRL/Mp-lpr/lpr mice.

T-cell-enriched populations obtained from lymph nodes (LNs) of 4-month-old MRL/Mp-lpr/lpr (MRL-lpr), C3H/HeJ-lpr/lpr (C3H-lpr), and C3H/HeJ-gld/gld (C3H-gld) mice were studied for the expression of B220, L3T4, and Lyt 2 antigens. A new B220+ L3T4+ phenotype was demonstrated in T-cell populations of these mice by two-color flow cytometry with phycoerythrin-conjugated monoclonal antibodies (MoAb) to L3T4 and FITC-anti-B220 MoAb. The generation of the T subset was apparently under the influence of the lpr or gld gene, since it could not be demonstrated in T-cell-enriched populations of MRL/Mp- +/+ and normal C3H mice. The expression level of L3T4 antigen on the T subset was lower than that on B220- L3T4+ cells, while the level of B220 antigen was similar to that of B220+ L3T4- or B220+ Lyt 2- cells. The B220+ L3T4+ phenotype appeared in LNs and spleens, but not in thymuses, of MRL-lpr mice as early as 2 months of age. Its proportion to whole LN T cells at this age was equivalent to that observed in 4-month-old mice. Functional studies on FACS-sorted cell populations revealed that the T subset similar to B220+ L3T4- cells possessed deficiencies in the IL-2-IL-2 receptor system. The appearance of the T subset with an intermediate phenotype and its functional defects suggests that lpr and gld genes in these autoimmune mice exert their influences on the ontogeny and function of L3T4+ T cells and contribute to the induction of early lupus.

Animals↗
PubMed1988

Amino acid sequence of rat argininosuccinate lyase deduced from cDNA.

Argininosuccinate lyase [EC 4.3.2.1] is an enzyme of the urea cycle in the liver of ureotelic animals. The enzymes of the urea cycle, including argininosuccinate lyase, are regulated developmentally and in response to dietary and hormonal changes, in a coordinated manner. The nucleotide sequence of rat argininosuccinate lyase cDNA, which was isolated previously (Amaya, Y., Kawamoto, S., Oda, T., Kuzumi, T., Saheki, T., Kimula, S., & Mori, M. (1986) Biochem. Int. 13, 433-438), was determined. The cDNA clone contained an open reading frame encoding a polypeptide of 461 amino acid residues (predicted Mr = 51,549), a 5'-untranslated sequence of 150 bp, and a 3'-untranslated sequence of 41 bp. The amino acid composition of rat liver argininosuccinate lyase predicted from the cDNA sequence is in close agreement with that determined on the purified enzyme. The predicted amino acid sequences of the human and yeast enzymes along the entire sequences (94 and 39%, respectively), except for a region of 66 residues of the human enzyme near the COOH terminus. However, the sequence of this region of the human enzyme predicted from another reading frame of the human enzyme cDNA is homologous with the corresponding sequences of the rat and yeast enzymes. Therefore, the human sequence should be re-examined. Lysine-51, the putative binding site for argininosuccinate, and the flanking sequences are highly conserved among the rat, steer, human, and yeast enzymes.

Amino Acid Sequence↗
PubMed1988

Structure of the human ornithine transcarbamylase gene.

Complementary and genomic DNA clones corresponding to the human ornithine transcarbamylase (OTC) [EC 2.1.3.3]mRNA have been isolated and analyzed. The OTC gene is about 73 kilobase pairs (kb) long and contains 10 exons interrupted by 9 introns of highly variable sizes. The smallest intron is 80 base pairs and the largest, 21.7 kb. The 5'- and 3'-flanking regions, entire exons and all the exon/intron boundaries were sequenced. The nucleotide and deduced amino acid sequences of isolated OTC cDNAs as well as the corresponding regions of the genomic DNA were compared with those of human OTC cDNA (Horwich, A.L., Fenton, W.A., Williams, K.R., Kalousek, F., Kraus, J.P., Doolittle, R.F., Koningsberg, W., & Rosenberg, L.E. (1984) Science 224, 1068-1074). We found 20 nucleotide substitutions among these sequences, of which 6 related to amino acid changes. The nature of these nucleotide substitutions is discussed.

Amino Acid Sequence↗
PubMed1988

Phenotypic and functional analyses on T-cell subsets in lymph nodes of MRL/Mp-lpr/lpr mice.

By means of killing and/or FACS sorting the double-negative (DN) Lyt2-, L3T4- cells, Lyt2+ or L3T4+ cells and B220- cell populations were separated from T-cell-enriched lymph node (LN) cells of 4- to 5-month-old MRL/Mp-lpr/lpr mice. These highly purified cell populations were examined for their proliferative responses, interleukin 2 (IL2) production and expression of IL2 receptor (IL2R) in response to phorbol myristate acetate (PMA) and the calcium ionophore A23187 (A2) or PMA plus concanavalin A. The DNT-cell population was unable to respond to the stimuli and did not express IL2R. Thus the DN T cells, the major population responsible for the lymphadenopathy, possess fundamental defects in signal transduction as well as in the IL2-IL2R-mediated function. On the other hand, Lyt2+ or L3T4+ T cells obtained by sorting or B220- cells purified by the sorting after killing B220+ cells, exhibited proliferative responses indistinguishable from that of LN cells of the congenic MRL/Mp-+/+(+/+) mice. These cells also expressed IL2R after stimulation, however, the amount of IL2 produced was significantly lower than that produced by congenic +/+ cells. This suggested that phenotypically normal Lyt2+ or L3T4+ T cells of lpr LNs also possess a partial defect in the signal transduction system for IL2 production under the influence of the lpr gene.

Animals↗
PubMed1988

Effects of inhalation anesthetics on airway dynamics determined by phasor analysis of respiratory impedance using the forced oscillation method.

By expressing the respiratory system as a two-compartment model and assigning a phasor in the complex plane to each impedance element in the model, the phasor of the respiratory impedance could be constructed graphically, the frequency characteristics determined from the locus of the latter and the effects of variations in the model elements on the frequency characteristics could also be expressed as the locus of the latter. Conversely, it is possible to detect small changes in mechanical properties on the respiratory system by plotting its frequency characteristics on the complex plane. We studied the effects of typical inhalation anesthetics, halothane, enflurane and isoflurane, on the airway dynamics by this method. The inhalation concentration of 1 MAC of halothane and/or enflurane was found to produce bronchodilation associated with a significant reduction in airway resistance, but isoflurane had no such effects. As the magnitude of changes in the real part at 1 Hz, the estimated airway resistance was -2.1 cmH2O/1/s (-25% of the mean value) for halothane, and -0.8 cmH2O/1/s (-11%) for enflurane.

Adult↗