PubMed Health⌕ Search

Biomedical subjects

M Horikoshi

Publications and source records attributed to M Horikoshi.

At least 19 recordsLinked to original sources
PubMed2005

Absence of an association between the polymorphisms in the genes encoding adiponectin receptors and type 2 diabetes.

AIMS/HYPOTHESIS: Secreted by adipocytes, adiponectin is a hormone that acts as an antidiabetic and anti-atherogenic adipokine. We recently cloned the genes encoding two adiponectin receptors (ADIPOR1 and ADIPOR2). The aim of this study was to examine whether ADIPOR1 and/or ADIPOR2 play a major role in genetic susceptibility to insulin resistance or type 2 diabetes in the Japanese population. METHODS: By direct sequencing and a search of public databases, we identified single nucleotide polymorphisms (SNPs) in ADIPOR1 and ADIPOR2, and investigated whether these SNPs are associated with insulin resistance and type 2 diabetes in the Japanese population. RESULTS: The linkage disequilibrium (LD) in the chromosomal region of ADIPOR1 was almost completely preserved, whereas the LD in ADIPOR2 was less well preserved. None of the SNPs in ADIPOR1 or ADIPOR2 were significantly associated with insulin resistance or type 2 diabetes. No differences in ADIPOR1 or ADIPOR2 haplotype frequencies were observed between type 2 diabetic and non-diabetic subjects. CONCLUSIONS/INTERPRETATION: Genetic variations in ADIPOR1 or ADIPOR2 are unlikely to lead to a common genetic predisposition to insulin resistance or type 2 diabetes in the Japanese population.

Diabetes Mellitus, Type 2↗
PubMed2001

Identification of mouse Jun dimerization protein 2 as a novel repressor of ATF-2.

A mouse cDNA that encodes a DNA-binding protein was identified by yeast two-hybrid screening, using activating transcription factor-2 (ATF-2) as the bait. The protein contained a bZIP (basic amino acid-leucine zipper region) domain and its amino acid sequence was almost identical to that of rat Jun dimerization protein 2 (JDP2). Mouse JDP2 interacted with ATF-2 both in vitro and in vivo via its bZIP domain. It was encoded by a single gene and various transcripts were expressed in all tested tissues of adult mice, as well as in embryos, albeit at different levels in various tissues. Furthermore, mouse JDP2 bound to the cAMP-response element (CRE) as a homodimer or as a heterodimer with ATF-2, and repressed CRE-dependent transcription that was mediated by ATF-2. JDP2 was identified as a novel repressor protein that affects ATF-2-mediated transcription.

3T3 Cells↗
PubMed2001

Cell death with predominant apoptotic features in Saccharomyces cerevisiae mediated by deletion of the histone chaperone ASF1/CIA1.

BACKGROUND: Although no potential homologues of multicellular apoptotic genes (e.g. Bax, Bak, Bcl-2, caspases and p53) have been identified in a unicellular eukaryote, previous reports contain several implications of the apoptotic behaviour of yeasts (i.e. Saccharomyces cerevisiae and Schizosaccharomyces pombe). Therefore, whether or not yeast undergoes apoptosis has been a topic of some debate. hCCG1, which is the largest subunit of TFIID and a histone acetyltransferase, appears to be involved in the regulation of apoptosis. The factor hCIA interacts with hCCG1 and functions as a histone chaperone in mammalian cells; its homologue in yeast is Asf1p/Cia1p. Therefore, we anticipated that a yeast mutant in Asf1p/Cia1p would be a valuable tool for studying apoptosis in yeast. RESULTS: We established a strain of S. cerevisiae lacking the histone chaperone ASF1/CIA1. This disruptant, asf1/cia1, arrested preferentially at the G2/M-phase and died. We systematically analysed the phenotype associated with the death of this mutant yeast and identified many changes, such as fragmentation of the nuclei, condensation and fragmentation of chromatin, reduction of the mitochondrial membrane-potential, dysfunction of the mitochondrial proton pump, and a discernible release of cytochrome c to cytoplasm that resembles those in apoptotic multicellular organisms. Other changes potentially associated with the death in our mutant included a reduction in the vacuolar membrane potential, dysfunction of the vacuolar proton pump, reduction of endocytosis, and the presence of many autophagic bodies. However, these mutant yeast cells also showed cellular enlargement, which is characteristic of necrosis. CONCLUSIONS: Cell death in S. cerevisiae occurs with a phenotype that largely resembles apoptosis in multicellular organisms, but that has some features of necrosis. Therefore, we indicate that yeast undergoes a 'prototypal active cell death' that retains some characteristics of passive cell death (necrosis). In addition, we think that active cell death is ubiquitously the essential attribute of life. Although such an active cell death system in yeast remains open to confirmation, we speculate that deletion of the histone chaperone Asf1p/Cia1p inhibits the normal assembly/disassembly of nucleosomes in yeast and thereby initiates the active cell death system.

Animals↗
PubMed2001

Serine acetyltransferase involved in cysteine biosynthesis from spinach: molecular cloning, characterization and expression analysis of cDNA encoding a plastidic isoform.

A cDNA clone that encodes a chloroplast-localizing isoform of serine acetyltransferase (SATase) (EC 2.3.1.30) was isolated from spinach (Spinacia oleracea L.). The cDNA encodes a polypeptide of 347 amino acids containing a putative transit peptide of ca. 60-70 amino acids at the N-terminal. Deduced amino acid sequence of SATase from spinach exhibited homology with other SATases from plants. DNA blot hybridization analysis showed the presence of 2-3 copies of Sat gene in the genome of spinach. RNA blot hybridization analysis indicated the constitutive expression of Sat gene in green and etiolated seedlings of spinach. Bacterial expression of the cDNA could directly rescue the cysteine auxotrophy of Escherchia coli caused by a lack of SATase locus (cysE). Catalytically active SATase protein was produced in E. coli cells. L-Cysteine, an end product of the cysteine biosynthetic pathway, inhibited the activity of recombinant spinach SATase, indicating the regulatory function of SATase in this metabolic pathway. A chloroplastic localization of this spinach SATase was revealed by the analyses of transgenic plant expressing transit peptide of SATase-beta-glucuronidase (GUS) fusion protein, and transient expression using the transit peptide-green fluorescent protein (GFP) fusion protein. The result from in vitro translation analysis suggests that this cDNA may encode both plastidic and cytosolic SATases.

Acetyltransferases↗
PubMed2001

Cerebrospinal fluid immunocytochemical analysis and neuroimaging in the diagnosis of primary leptomeningeal melanoma. Case report.

A 20-year-old man presented with slowly progressing symptoms indicative of increased intracranial pressure. Two weeks later he underwent surgery for placement of a ventriculoperitoneal shunt. Cytological examination of the patient's cerebrospinal fluid (CSF) revealed atypical cells that contained no detectable melanin deposits, but proved to be immunocytochemically positive for monoclonal antibodies to melanocytic cells (HMB-45) and S-100 protein. Dermatological and ophthalmological examinations failed to demonstrate any abnormalities. On the basis of these findings, a diagnosis of primary leptomeningeal melanoma was made. Gadolinium-enhanced magnetic resonance (MR) images of the brain and spinal regions obtained 2 months after admission demonstrated typical widespread leptomeningeal enhancement. Results of technetium-99m-hexakis (2-methoxyisobutyl isonitrile) single-photon emission computerized tomography (99mTc-MIBI SPECT) scanning revealed intense uptake of the isotope in the leptomeningeal regions and some cisterns. The patient's condition progressively worsened and he died 5 months after admission. The diagnosis was confirmed at autopsy. Immunocytochemical analysis of CSF performed using HMB-45 and S-100 protein antibodies is important for the diagnosis of leptomeningeal melanoma because of the test's simplicity, high specificity, and sensitivity. Gadolinium-enhanced MR imaging is used to demonstrate the extent of the leptomeningeal melanoma. An additional and supplemental neuroimaging modality, 99mTc-MIBI SPECT scanning has good potential for the detection and diagnosis of leptomeningeal melanoma.

Adult↗
PubMed2000

Involvement of the TIP60 histone acetylase complex in DNA repair and apoptosis.

It is well known that histone acetylases are important chromatin modifiers and that they play a central role in chromatin transcription. Here, we present evidence for novel roles of histone acetylases. The TIP60 histone acetylase purifies as a multimeric protein complex. Besides histone acetylase activity on chromatin, the TIP60 complex possesses ATPase, DNA helicase, and structural DNA binding activities. Ectopic expression of mutated TIP60 lacking histone acetylase activity results in cells with defective double-strand DNA break repair. Importantly, the resulting cells lose their apoptotic competence, suggesting a defect in the cells' ability to signal the existence of DNA damage to the apoptotic machinery. These results indicate that the histone acetylase TIP60-containing complex plays a role in DNA repair and apoptosis.

Acetyltransferases↗
PubMed2000

Regulation of interaction of the acetyltransferase region of p300 and the DNA-binding domain of Sp1 on and through DNA binding.

BACKGROUND: The coactivator p300 acts as a transcriptional adaptor for many DNA-binding activators. The finding that p300 possesses intrinsic acetyltransferase activity which, by chemically modifying histone tails affects the nucleosomal environment and transcription, has greatly advanced our understanding of its function. Subsequent recent studies have shown that non-histone proteins are also acetylated. However, one central question which has remained unanswered is how the coactivator/acetyltransferase interacts with DNA-binding activators to modulate their actions. RESULTS: Here we have demonstrated physical and functional interaction between the acetyltransferase region of p300 and the DNA-binding domain (DBD) of the transcription factor Sp1. This interaction stimulates DNA binding by the DBD of Sp1, which is mediated primarily by physical interaction rather than acetylation, despite acetylation of the DBD of Sp1 by the acetyltransferase region of p300. Furthermore, DNA binding by the DBD of Sp1 inhibits both its association and acetylation by the acetyltransferase region of p300. CONCLUSIONS: These findings suggest a new role for p300 in regulating promoter access by DNA-binding activators through multiple regulatory interactions.

Acetylation↗
PubMed2000

A human homologue of yeast anti-silencing factor has histone chaperone activity.

BACKGROUND: Structural changes in chromatin play essential roles in regulating eukaryotic gene expression. Silencing, potent repression of transcription in Saccharomyces cerevisiae, occurs near telomeres and at the silent mating-type loci, as well as at rDNA loci. This type of repression relates to the condensation of chromatin that occurs in the heterochromatin of multicellular organisms. Anti-silencing is a reaction by which silenced loci are de-repressed. Genetic studies revealed that several factors participate in the anti-silencing reaction. However, actions of factors and molecular mechanisms underlying anti-silencing remain unknown. RESULTS: Here we report the functional activity of a highly evolutionarily conserved human factor termed CIA (CCG1-interacting factor A), whose budding yeast homologue ASF1 has anti-silencing activity. Using yeast two-hybrid screening, we isolated histone H3 as an interacting factor of CIA. We also showed that CIA binds to histones H3/H4 in vitro, and that the interacting region of histone H3 is located in the C-terminal helices. Considering the functional role of CIA as a histone-interacting protein, we found that CIA forms a nucleosome-like structure with DNA and histones. CONCLUSIONS: These results show that human CIA, whose yeast homologue ASF1 is an anti-silencing factor, possesses histone chaperone activity. This leads to a better understanding of the relationship between chromatin structural changes and anti-silencing processes.

Amino Acid Sequence↗
PubMed2000

Functional interaction of general transcription initiation factor TFIIE with general chromatin factor SPT16/CDC68.

BACKGROUND: Transcriptional initiation of class II genes is one of the major targets for the regulation of gene expression and is carried out by RNA polymerase II and many auxiliary factors, which include general transcription initiation factors (GTFs). TFIIE, one of the GTFs, functions at the later stage of transcription initiation. As recent studies indicated the possibility that TFIIE may have a role in chromatin transcriptional regulation, we isolated TFIIE-interacting factors which have chromatin-related functions. RESULTS: Using the yeast two-hybrid screening system, we isolated the C-terminal part of the human homologue of Saccharomyces cerevisiae (y) Spt16p/Cdc68p, a general chromatin factor. The C-terminal part of human SPT16/CDC68 directly interacts with TFIIE, and ySpt16p/Cdc68p also interacts with yTFIIE (Tfa1p/Tfa2p), thus indicating the existence of an evolutionarily conserved interaction between TFIIE and SPT16/CDC68. Functional interaction of yTFIIE and ySpt16p/Cdc68p was examined using a conditional yTFIIE-alpha mutant strain. Over-expression of ySpt16p/Cdc68p suppressed the phenotype of cold sensitivity of the yTFIIE-alpha-cs mutant strain, and in vitro binding assays revealed that yTFIIE-alpha-cs mutant protein showed diminished binding affinity to ySpt16p/Cdc68p. CONCLUSIONS: These observations indicate that general transcription initiation factor TFIIE functionally interacts with general chromatin factor SPT16/CDC68, a finding which provides new insight into the involvement of TFIIE in chromatin transcription. This may well lead to a breakthrough in relationships between the transcription initiation process and structural changes in chromatin.

Amino Acid Sequence↗
PubMed2000

Purification, crystallization and preliminary X-ray crystallographic analysis of human CCG1-interacting factor B.

A novel human factor CIB (CCG1-interacting factor B) has been isolated using the yeast two-hybrid system. The 22 kDa CIB protein has been expressed in Escherichia coli, purified to homogeneity and crystallized in a form suitable for crystallographic studies. The protein was crystallized in the orthogonal space group P2(1)2(1)2(1), with unit-cell parameters a = 43.60 (2), b = 44.45 (1), c = 110.70 (5) A and one molecule in the asymmetric unit. The crystal diffracted beyond 2.2 A resolution using synchrotron radiation.

Cell Cycle Proteins↗
PubMed2000

[Essential thrombocythemia in transformation from myelodysplastic syndrome to acute myeloid leukemia with inv(3) after treatment for gastric cancer].

In March 1990, a 61-year-old man was given a diagnosis of essential thrombocythemia with a normal karyotype and subsequently treated with hydroxyurea. In November 1995, he underwent surgery for gastric cancer with thereafter received tegafur/uracil for 2 years. Refractory anemia with excess of blasts in transformation and chromosomal abnormalities including -5, -7, 20q-developed in August 1998. Combined chemotherapy with daunorubicin, cytarabine, mercaptopurine, and prednisolone, had only limited effectiveness. Acute myeloid leukemia was finally diagnosed in October 1998, and chromosomal analysis disclosed inv(3) in addition to -5 and -7. The appearance of inv(3) might be related to leukemic transformation of hematopoietic stem cell disease with an increase in the number of megakaryocytes and platelets.

Aged↗
PubMed2000

[Assessment of noninvasive therapy in lung cancer using lung perfusion images].

The purpose of this prospective study was to follow the changes in functional parameters of radionuclide lung perfusion scans and their role in prognostication of lung cancer cases after noninvasive therapy. We studied 91 patients of lung cancer treated with chemotherapy and/or radiotherapy during 1993 to 1997 in our hospital. Lung perfusion scans were acquired pre and post-therapy. An index of lung perfusion, called Improvement Ratio (IR) was defined as a change in the perfusion of diseased lung as a result of treatment. IR was calculated by the following equation under the assumption that perfusion of contralateral lung remained unaffected. [formula: see text] where Q and Q' are pulmonary arterial blood flow pre and post therapy respectively, p is perfusion ratio of diseased lung before therapy and q is that after therapy. We further studied the relationship between IR and change in tumor size. The influence of tumor location, histopathological diagnosis and prognosis of lung cancer were correlated with this newly defined index. IR in the group of patients with complete response or partial response was significantly higher than in those with poor response (2.72 +/- 0.78 versus 0.99 +/- 0.09, p < 0.05). There was no statistical difference between the group with and without radiotherapy. The score was significantly higher for patients with hilar disease compared to those with peripheral lesions (2.80 +/- 0.83 versus 1.02 +/- 0.03, p < 0.05). Similarly, patients with small cell lung cancer depicted higher values of IR than non-small cell lung cancer (3.36 +/- 1.10 versus 1.06 +/- 0.07, p < 0.05). All those subjects who showed IR > 1 had longer survival time than those with IR < 1 (p < 0.05). It is suggested that improvement in the perfusion of diseased lung predicted better prognosis. We conclude that the evaluation of physiological parameters during therapy using lung perfusion scanning, in addition to lesion size assessment will contribute to the comprehensive follow-up of lung cancer.

Adult↗
PubMed2000

[Regional assessment of treatment in lung cancer using lung perfusion and ventilation images].

In 30 patients with lung cancer undergoing non-surgical treatment, we performed perfusion lung imaging using 99mTc-MAA and inhalation lung studies using Technegas before and after treatment and evaluated regional perfusion and ventilation status in the lung regions where bronchogenic carcinoma was located. Regional ventilation status was preserved rather than perfusion counterpart (V > P) in 18 patients (18/30 = 60.0%) before treatment, while the former was better than the latter in 27 patients (27/30 = 90.0%) after treatment, indicating that regional ventilation status improved more significantly than regional perfusion counterpart after treatment (p = 0.005). We also classified the therapeutic effect for regional perfusion and ventilation status as improved, unchanged, or worsened, respectively; improvement in regional perfusion status was observed in 17 patients (56.7%) and that in regional ventilation status in 24 patients (80.0%). There was a statistically significant correlation between improved regional perfusion and ventilation status (p = 0.0018) when therapeutic effect was recognized. The patients who showed improvement in regional perfusion status after treatment always showed improved regional ventilation status, but 7 patients showed either unchanged or worsened regional perfusion status after treatment, although regional ventilation status was improved. In conclusion the pulmonary vascular beds seem more vulnerable to bronchogenic carcinoma and improvement in regional perfusion status was revealed to be more difficult than that in regional ventilation status after treatment.

Adult↗
PubMed1999

Analysis of TFIIH subunit through isolation of the gene from Schizosaccharomyces pombe corresponding to that of Saccharomyces cerevisiae SSL1, reveals the presence of conserved structural motifs.

We isolated a Schizosaccharomyces pombe (Sz. pombe) gene encoding the counterpart of the TFIIH subunit Homo sapiens (H. sapiens) p44 and Saccharomyces cerevisiae (S. cerevisiae) SSL1, and we named this gene product p47. Contrary to the case of SSL1, which is an essential gene of S. cerevisiae, p47 is not essential for the viability of Sz. pombe. The deduced amino acid sequence revealed that this TFIIH subunit is highly conserved during evolution. Comparison of the primary structures revealed differences in the predicted positions of introns in the Caenorhabditis elegans (C. elegans) gene encoding the p47 counterpart found during the genome project. A charged cluster in the N-terminal region is present in the two yeasts. Two putative zinc-binding motifs, an extended C2H2 zinc finger with a 'C8 motif' and a second putative zinc-binding motif common to the two TFIIH subunits, were also found, the former being completely conserved. The latter motif consists of five cysteine residues and is also present in hp44, SSL1 and another TFIIH subunit, human p34 (hp34). Since one zinc atom can bind to four ligands in zinc-binding motifs, the conservation of cysteine residues was given attention. This motif is completely conserved in p47 homologues derived from the four species. As one cysteine residue is not conserved among the homologues of hp34, the consensus of this motif is concluded to be Cys X2-Cys-X(10,12)-Cys-X2-Cys. This nucleotide sequence has been deposited in the GenBank Data Library under Accession Number AF017646.

Amino Acid Sequence↗
PubMed1999

Relationship between the subcellular localization and structures of catalytic domains of FKBP-type PPIases.

The Schizosaccharomyces pombe gene, fkp39(+), encoding a homolog of FKBP(FK506 binding protein)-type peptidyl prolyl cis-trans isomerase (PPIase), was isolated and the primary structure was determined. This gene product (SpFkbp39p) showed PPIase enzymatic activity in a chymotrypsin-dependent enzyme assay involving recombinant SpFkbp39p. Comparison of the primary structures of the catalytic domains of FKBPs, including SpFkbp39p, revealed that FKBPs could be classified into four groups. This categorization corresponding to the known subcellular localization of the FKBPs, makes the prediction of the subcellular localization of FKBPs based on their primary structures feasible. SpFkbp39p was considered to be a member of the nuclear-type FKBP group from this relationship between primary structure and subcellular localization. An immunofluorescence assay against HA-epitope-tagged SpFkbp39p revealed that SpFkbp39p is localized to the nucleus, as predicted. Residues conserved in a "group-specific" manner in the catalytic domain were mapped to their corresponding three-dimensional positions; these "group-specific" residues were located in close proximity in distinct regions mostly on the protein surface, which implies the presence of "group-specific" regulatory functional regions. We also found that nuclear-type FKBPs, including SpFkbp39p, have two highly conserved domains other than catalytic ones, with further basic and acidic charged regions, especially in the case of nuclear-type FKBPs. This is the first report indicating that there is a rule for the relationship between the subcellular localization and structure of the catalytic domain of a FKBP.

Amino Acid Sequence↗
PubMed1998

How do histone acetyltransferases select lysine residues in core histones?

Acetylation of specific lysines of core histone N-terminal tails correlates with chromatin assembly and specific regulation of gene expression. Core histones acetylated at particular lysines mediate effects on chromatin function; however, the manner in which different histone acetyltransferases (HATs) discriminate lysines is unknown. Here we propose a putative rule for lysine selection by HATs based on the primary sequence in the vicinity of lysines in the core histone N-terminal tails and in flanking sequence. This provides insight into the molecular basis of site selection of core histones by HATs.

Acetylation↗