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Biomedical subjects

M Yasunami

Publications and source records attributed to M Yasunami.

At least 19 recordsLinked to original sources
PubMed2005

Association of clinical features with HLA in chronic pulmonary thromboembolism.

The aetiology of chronic thromboembolic pulmonary hypertension (CTEPH) is largely unknown and may be heterogeneous, because there are several ethnic differences in the clinical characteristics of CTEPH. Female predominance and a higher ratio of chronic to acute pulmonary thromboembolism have been reported in Japan as compared with the USA. Because such ethnic differences may be controlled by genetic factors, the current study investigated HLA polymorphisms in Japanese patients with CTEPH. HLA typing by serological and/or DNA typing methods was performed (for HLA-A, B, DPB1, DRB1) in 80 patients and 678 controls, and the association of clinical characteristics with HLA alleles was studied. The frequencies of HLA-B*5201 (40 versus 24%) and DPB1*0202 (19 versus 6%) were significantly higher in the patients. HLA-B*5201 positive patients showed a significant female predominance. Total pulmonary vascular resistance and mixed venous oxygen tension were better in the HLA-B*5201 positive patients. In contrast, cardiac index and gas exchange parameters were worse in the HLA-DPB1*0202 positive patients. In the patients carrying HLA-B*5201 and/or -DPB1*0202, the frequency of deep vein thrombosis was significantly lower than the other patients. These observations suggested that both the susceptibility and clinical characteristics of chronic thromboembolic pulmonary hypertension were controlled in part by the HLA-B and -DPB1 loci.

Adult↗
PubMed2001

Identification and characterization of cell-specific enhancer elements for the mouse ETF/Tead2 gene.

We have identified and characterized by transient transfection assays the cell-specific 117-bp enhancer sequence in the first intron of the mouse ETF (Embryonic TEA domain-containing factor)/Tead2 gene required for transcriptional activation in ETF/Tead2 gene-expressing cells, such as P19 cells. The 117-bp enhancer contains one GC-rich sequence (5'-GGGGCGGGG-3'), termed the GC box, and two tandemly repeated GA-rich sequences (5'-GGGGGAGGGG-3'), termed the proximal and distal GA elements. Further analyses, including transfection studies and electrophoretic mobility shift assays using a series of deletion and mutation constructs, indicated that Sp1, a putative activator, may be required to predominate over its competition with another unknown putative repressor, termed the GA element-binding factor, for binding to both the GC box, which overlapped with the proximal GA element, and the distal GA element in the 117-bp sequence in order to achieve a full enhancer activity. We also discuss a possible mechanism underlying the cell-specific enhancer activity of the 117-bp sequence.

Animals↗
PubMed2001

Encoding tasks and the processing of perceptual information in young and older adults.

This study examined the degree to which different tasks promote the encoding of the characteristics of a talker's voice in young and older adults, and whether these characteristics encoded in long-term memory facilitate spoken word identification under difficult listening conditions. During the encoding phase, participants were given extensive exposure to the voices of two talkers and performed tasks that focused their attention on either voice characteristics (explicitly or incidentally) or linguistic information. Subsequently, participants identified novel words masked by noise, half of which were spoken by one of the familiar talkers and half by an unfamiliar talker. Young adults identified with greater accuracy words spoken in a familiar voice, whereas older adults benefited from voice familiarity only under instructions that promoted attention to voice characteristics either explicitly or incidentally. Age-related declines in sensory uptake (hearing loss) accounted for most of these task-dependent voice effects.

Adolescent↗
PubMed2000

Structure of the mouse NDRF gene and its regulation during neuronal differentiation of P19 cells.

We have isolated and characterized the mouse gene for NDRF (neuroD-related factor), a basic helix-loop-helix transcription factor implicated in neural development and function. The gene consists of two exons and the entire protein-coding sequence is encoded by a single downstream exon. RNA blot hybridization analysis revealed that NDRF mRNA was detectable at day 4 and increased to a maximal level at day 6 during neuronal differentiation of P19 cells. To elucidate the regulatory mechanisms of the NDRF gene expression during this process, a construct containing the genomic DNA fragment of about 3 kbp upstream of the NDRF coding region fused to a luciferase reporter gene was transfected into P19 cells, and stable transformants were pooled for assay of luciferase activities. When the stable transformants were treated with RA and aggregated to induce neuronal differentiation, the luciferase activities were induced in a temporal expression pattern similar to that of the endogenous NDRF mRNA. Further experiments using a series of deletion and mutation constructs indicated that the 376-bp sequence in the 5'-flanking region of the NDRF gene is important, and that one of the E boxes in the sequence plays a critical role in the regulated expression. Transient transfection experiments also showed that the same E box is required for the transactivation of the NDRF promoter activity by neurogenin 1. These results suggest that the NDRF gene expression is regulated by an E box-binding factor during neuronal differentiation of P19 cells.

Animals↗
PubMed1999

Cloning from insulinoma cells of synapsin I associated with insulin secretory granules.

Synapsin I is a synaptic vesicle-associated protein involved in neurotransmitter release. The functions of this protein are apparently regulated by Ca2+/calmodulin-dependent protein kinase II (CaM kinase II). We reported evidence for CaM kinase II and a synapsin I-like protein present in mouse insulinoma MIN6 cells (Matsumoto, K., Fukunaga, K., Miyazaki, J., Shichiri, M., and Miyamoto, E. (1995) Endocrinology 136, 3784-3793). Phosphorylation of the synapsin I-like protein in these cells correlated with the activation of CaM kinase II and insulin secretion. In the present study, we screened the MIN6 cDNA library with the full-length cDNA probe of rat brain synapsin Ia and obtained seven positive clones; the largest one was then sequenced. The largest open reading frame deduced from the cDNA sequence of 3695 base pairs encoded a polypeptide of 670 amino acids, which exhibited significant sequence similarity to rat synapsin Ib. The cDNA contained the same sequence as the first exon of the mouse synapsin I gene. These results indicate that synapsin Ib is present in MIN6 cells. Synapsin I was expressed in normal rat islets, as determined by reverse transcriptase-polymerase chain reaction analysis. Immunoblot analysis after subcellular fractionation of MIN6 cells demonstrated that synapsin Ib and delta subunit of CaM kinase II co-localized with insulin secretory granules. By analogy concerning regulation of neurotransmitter release, our results suggest that phosphorylation of synapsin I by CaM kinase II may induce the release of insulin from islet cells.

Amino Acid Sequence↗
PubMed1999

Association of polymorphism in the NeuroD/BETA2 gene with type 1 diabetes in the Japanese.

NeuroD/BETA2, a transcription factor of the insulin gene, also plays an important role in the development of pancreatic beta-cells. Recently, the NeuroD/BETA2 gene has been mapped to the long arm of human chromosome 2 (2q32) where the IDDM7 gene has previously been mapped, implying its involvement in diabetes. To identify mutations in the NeuroD/BETA2 gene that may predispose patients to develop diabetes, we studied the gene in 50 Japanese subjects with diabetes (4 with type 1 and 46 with type 2) by the polymerase chain reaction (PCR) followed by single-strand conformation polymorphism and sequencing analyses. Further analysis was performed in 392 Japanese subjects (60 with type 1 and 158 with type 2 diabetes and 174 healthy control subjects) by mismatch PCR restriction fragment length polymorphism. We found a DNA polymorphism of the NeuroD/BETA2 gene. A nucleotide G-to-A transition results in the substitution of alanine to threonine at codon 45 (Ala45Thr). The frequencies of heterozygotes for the Ala45Thr variant were 9.8% in the control subjects, 9.5% in the patients with type 2 diabetes, and 25.0% in the patients with type 1 diabetes, a significant difference (P = 0.006). Because the variant of the NeuroD/BETA2 gene (Ala45Thr) is associated with type 1 but not type 2 diabetes, it may be implicated in the loss of pancreatic beta-cells in type 1 diabetes.

Adult↗
PubMed1997

Superoxide-mediated cytotoxicity in superoxide dismutase-deficient fetal fibroblasts.

To investigate the roles of CuZn superoxide dismutase (CuZnSOD) and Mn superoxide dismutase (MnSOD) in oxygen radical-mediated cytotoxicity and to distinguish the actions of these two enzymes, fetal fibroblasts were derived from mouse fetuses that are either deficient in CuZnSOD (Sod1-/+ and -/-) or MnSOD (Sod2-1+ and -/-) for in vitro studies. Whereas the phenotype of the Sod1 mutant animals did not differ from that of their normal littermates, the growth of Sod1-/- fetal fibroblasts was only 25% of that of the -/+ and +/+ cells. On the other hand, although almost all homozygous Sod2 mutant animals (-/-) died within 10 days after birth, cultivation of Sod2-/- fetal fibroblasts was possible and their growth was about 60% that of -/+ and +/+ cells. When cultured cells were subjected to treatment with paraquat to assess their ability to grow in the presence of high levels of superoxide radicals, Sod1-/- cells were 80 times more sensitive and Sod2-/- cells were 12 times more sensitive to paraquat than wild-type cells. In addition, whereas the loss of 50% CuZnSOD rendered Sod1-/+ cells almost twice more sensitive to paraquat than +/+ cells, loss of 50% MnSOD had no effect on paraquat sensitivity. Our results suggest that CuZnSOD-deficient cells are more sensitive to oxygen toxicity than are MnSOD-deficient cells, that paraquat causes free radical-induced damage in both the mitochondria and cytoplasm, and that SOD compartmentalized in the cytosol cannot compensate for the loss of SOD in the mitochondria and vice versa.

Animals↗
PubMed1996

A novel family of TEA domain-containing transcription factors with distinct spatiotemporal expression patterns.

We cloned two novel types of TEA domain-containing transcription factor (ETFR-1 and -2) cDNAs. Amino acid sequences deduced for ETFR-1 and -2 as well as those of other known proteins of the same family, TEF-1 and ETF, exhibited significant identity (63-75% overall) to each other not only in the TEA DNA binding domain but also in the C-terminal regions. Northern blot analysis revealed that both the mRNAs were expressed in embryos as well as in many adult tissues, although their levels of expression varied. The results demonstrate that the mammalian TEA domain-containing transcription factor family consists of at least four distinct members, TEF-1, ETF, ETFR-1, and ETFR-2, which exhibit overlapping but differing spatiotemporal expression patterns, suggesting their redundant yet unique roles involved in not only developmental control but also tissue-specific regulation.

Aging↗
PubMed1996

Structural organization and chromosomal assignment of the mouse embryonic TEA domain-containing factor (ETF) gene.

Embryonic TEA domain-containing factor (ETF) belongs to the family of proteins structurally related to transcriptional enhancer factor-1 (TEF-1) and is implicated in neural development. Isolation and characterization of the cosmid clones encoding the mouse ETF gene (Etdf) revealed that Etdf spans approximately 17.9 kb and consists of 12 exons. The exon-intron structure of Etdf closely resembles that of the Drosophila scalloped gene, indicating that these genes may have evolved from a common ancestor. The multiple transcription initiation sites revealed by S1 protection and primer extension analyses are consistent with the absence of the canonical TATA and CAAT boxes in the 5'-flanking region, which contains many potential regulatory sequences, such as the E-box, N-box, Sp1 element, GATA-1 element, TAATGARAT element, and B2 short interspersed element (SINE) as well as several direct and inverted repeat sequences. The Etdf locus was assigned to the proximal region of mouse chromosome 7 using fluorescence in situ hybridization and linkage mapping analyses. These results provide the molecular basis for studying the regulation, in vivo function, and evolution of Etdf.

Amino Acid Sequence↗
PubMed1996

Cloning and expression of a rat brain basic helix-loop-helix factor.

We cloned two rat cDNAs of brain basic helix-loop-helix factor 1 (BHF1). These have an identical coding region, contain 357 amino acids and exhibit 94.6% identity to MATH-2/NEX1 in the basic helix-loop-helix region. BHF1mRNAs are dominantly expressed in the brain particularly in the cerebellum, in the adult bovine, rat and mouse. Two shorter BHF1mRNAs (1.6 kb and 1.8 kb) were also detected in the mouse embryo, and these decreased in the developmental process. These results suggest that BHF1 may play important roles in cerebellum-specific functions and development of neurons.

Amino Acid Sequence↗
PubMed1996

Molecular cloning and characterization of a cDNA encoding a novel basic helix-loop-helix protein structurally related to Neuro-D/BHF1.

We cloned a novel basic helix-loop-helix protein, NDRF (NeuroD-related factor), cDNA. NDRF contains 383 amino acids and exhibits 53.4% and 52.2% sequence identity to NeuroD and MATH-2/NEX-1, respectively. NDRF mRNA appears in the brain of 12-day-old mouse embryos and is localized in certain regions of the adult brain, such as the hippocampus, dentate gyrus and cerebellum, Thus, the structure and expression patterns of NDRF are similar to but distinct from those of NeuroD and MATH-2/NEX-1, suggesting that NDRF may play distinct roles in neural development and plasticity as a novel member of the NeuroD family.

Amino Acid Sequence↗
PubMed1995

Molecular characterization of cDNA encoding a novel protein related to transcriptional enhancer factor-1 from neural precursor cells.

We identified a novel cDNA related to that of transcriptional enhancer factor-1 (TEF-1) during the course of isolation and characterization of cDNAs, whose mRNAs are preferentially expressed in the mouse neural precursor cells. The putative polypeptide, termed embryonic TEA domain-containing factor (ETF), deduced from the nucleotide sequence contains 445 amino acids and shares 66% amino acid identity with mouse and human TEF-1 proteins. The primary structure of the TEA domain, a probable DNA-binding domain, and the specific DNA binding activity to the GT-IIC motif of ETF are indistinguishable from those of the known vertebrate TEF-1 proteins. However, the expression of the ETF gene is strictly regulated in developing embryos and is limited to certain tissues, such as the hindbrain of a 10-day-old mouse embryo, in contrast to the ubiquitous expression pattern of the TEF-1 gene. These results suggest that ETF is a novel mammalian member of the TEA domain-containing transcription factor family and may be involved in the gene regulation of the neural development. We have discussed the possible existence of multiple subtypes of the mammalian TEF-1 family proteins, which may play different roles in cellular and development gene regulation.

Amino Acid Sequence↗
PubMed1992

Allele-specific expression of the cytoplasmic exon of HLA-DQB1 gene.

The beta chain of the HLA-DQ molecule is shorter by eight amino acid residues than other major histocompatibility complex class II beta chains due to elimination of the fifth exon coding for part of the cytoplasmic domain. This elimination is caused by one base substitution in the splice acceptor site of the exon. We found that two HLA-DQB1 alleles, DQB1*0503 and DQB1*0601, did not have this substitution, and the exon was utilized in these two alleles. However, two forms of HLA-DQB mRNA, with or without exon 5, were generated in Epstein-Barr virus-transformed cell lines homozygous for DQB1*0503 or DQB1*0601, indicating alternative mRNA splicing. The alternative splicing of DQB1*0601 mRNA was also found in peripheral blood lymphocytes and L cell transfectants. To investigate the functional relevance of the allele-specific long cytoplasmic tail of HLA-DQ beta chain, we developed three types of L cell transfectants expressing exclusively the HLA-DQw6 molecules with short cytoplasmic tail, long cytoplasmic tail, or both forms of the beta chain, and used them as antigen presenting cells for streptococcal cell wall antigen-specific T cell lines. These three types of transfectants could function almost equally well as antigen presenting cells. It was thus demonstrated that both forms of HLA-DQ beta chain, with or without eight amino acid residues coded for by the exon 5, can be associated with the HLA-DQ alpha chain, be expressed on the cell surface, and function as restriction molecules in antigen recognition by the CD4+ T cells.

Alleles↗
PubMed1991

A human alcohol dehydrogenase gene (ADH6) encoding an additional class of isozyme.

The human alcohol dehydrogenase (ADH; alcohol:NAD+ oxidoreductase, EC 1.1.1.1) gene family consists of five known loci (ADH1-ADH5), which have been mapped close together on chromosome 4 (4q21-25). ADH isozymes encoded by these genes are grouped in three distinct classes in terms of their enzymological properties. A moderate structural similarity is observed between the members of different classes. We isolated an additional member of the ADH gene family by means of cross-hybridization with the ADH2 (class I) cDNA probe. cDNA clones corresponding to this gene were derived from PCR-amplified libraries as well. The coding sequence of a 368-amino-acid-long open reading frame was interrupted by introns into eight exons and spanned approximately 17 kilobases on the genome. The gene contains a glucocorticoid response element at the 5' region. The transcript was detected in the stomach and liver. The deduced amino acid sequence of the open reading frame showed about 60% positional identity with known human ADHs. This extent of homology is comparable to interclass similarity in the human ADH family. Thus, the newly identified gene, which is designated ADH6, governs the synthesis of an enzyme that belongs to another class of ADHs presumably with a distinct physiological role.

Alcohol Dehydrogenase↗
PubMed1991

HLA-DQ-restricted CD4+ T cells specific to streptococcal antigen present in low but not in high responders.

We have found that the low immune response to streptococcal cell wall Ag (SCW) was inherited as a dominant trait and was linked to HLA, as deduced from family analysis. In the present report, HLA class II alleles of healthy donors were determined by serology and DNA typing to identify the HLA alleles controlling low or high immune responses to SCW. HLA-DR2-DQA1*0102-DQB1*0602(DQw6)-Dw2 haplotype or HLA-DR2-DQA1*0103-DQB1*0601(DQw6)-DW12 haplotype was increased in frequency in the low responders and the frequency of HLA-DR4-DRw53-DQA1*0301-DQB1*0401(DQw4)-Dw15 haplotype or HLA-DR9-DRw53-DQA1*0301-DQB1*0303(DQw3)-Dw23 haplotype was increased in the high responders to SCW. Homozygotes of either DQA1*0102 or DQA1*0103 exhibited a low responsiveness to SCW and those of DQA1*0301 were high responders. The heterozygotes of DQA1*0102 or 0103 and DQA1*0301 showed a low response to SCW, thereby confirming that the HLA-linked gene controls the low response to SCW, as a dominant trait. Using mouse L cell transfectants expressing a single class II molecule as the APC, we found that DQw6(DQA1*0103 DQB1*0601) from the low responder haplotype (DR2-DQA1*0103-DQB1*0601(DQw6)-Dw12) activated SCW-specific T cell lines whereas DQw4(DQA1*0301 DQB1*0401) from the high responder haplotype (DR4-DRw53-DQA1*0301-DQB1*0401(DQw4)-Dw15) did not activate T cell lines specific to SCW. However, DR4 and DR2 presented SCW to CD4+ T cells in both the high and low responders to SCW, hence the DR molecule even from the low responder haplotype functions as an restriction molecule in the low responders. Putative mechanisms linked to the association between the existence of DQ-restricted CD4+ T cells specific to SCW, and low responsiveness to SCW are discussed.

Bacterial Proteins↗
PubMed1991

High precursor frequency of human T cells reactive to HLA-DQ molecules expressed on mouse L cell transfectants.

In humans, the HLA-DR molecule is a major stimulatory molecule of allogeneic mixed lymphocyte reactions (MLR) and a major restriction molecule for the presentation of soluble antigens to the T cell. Little is known of the biological function of HLA-DQ. To examine the size of the repertoire of precursor T cells recognizing the autologous or allogeneic HLA-DQ molecule, the frequency of T cells reactive to HLA-DQ was estimated in comparison with T cells reactive to HLA-DR. We made use of a limiting dilution analysis and mouse L cells transfectants expressing the HLA-DR or -DQ molecule, as stimulators. Human T cells recovered from a primary MLR stimulated with allogeneic peripheral blood lymphocytes (PBL) proliferated in response to L cell transfectants expressing HLA class II genes shared by the stimulator cells in the primary MLR. This observation suggested that the HLA class II molecules on L cell transfectants shared to some extent epitopes for alloreactive T cells with those expressed on human PBL. The precursor frequencies of CD4+ T cells reactive to allogeneic or autologous DQ molecules were as high as those of T cells reactive to allogeneic DR molecules and were estimated to be 1/800-1/1800. The frequency of the T cells reactive to autologous DR molecules was low (1/7200-1/16,000). The biological significance of the high frequency of HLA-DQ-reactive precursor T cells is discussed.

Animals↗