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result(s) for
"Toyoshima, M"
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Transferrin facilitates the formation of DNA double-strand breaks via transferrin receptor 1: the possible involvement of transferrin in carcinogenesis of high-grade serous ovarian cancer
2016
Fallopian tubal epithelium is a candidate for the origin of high-grade serous ovarian cancer. Transferrin-containing follicular fluid and/or retrograde menstrual blood are possible risk factors for carcinogenesis. Accumulation of DNA double-strand breaks (DNA-DSBs) in the fallopian tubal epithelium is considered to play an important role in the development of cancer. However, the mechanisms by which DNA-DSBs accumulate have not yet been fully elucidated. The hydroxyl radical, which is produced in a Fenton reaction catalyzed by an iron ion, serves as a potent DNA-DSB-inducing molecule, raising the potential of an iron ion transporter of transferrin in the formation of DNA-DSBs. We studied the potential involvement of transferrin in DNA damage and the development of ovarian cancer. Treatment with transferrin facilitated the formation of histone 2AX phosphorylated at Serine 139 (γH2AX), which is known as a DNA-DSB marker, in human fallopian tube secretory epithelial cells and A2780 ovarian cancer cells. Knockdown of transferrin receptor 1 (TfR1), but not transferrin receptor 2, suppressed the transferrin uptake and consequent formation of γH2AX. As hydroxyl radicals in reactive oxygen species (ROS) are involved in DNA-DSBs, the formation of ROS was determined. Treatment with TfR1-specific small interference RNAs significantly diminished transferrin-induced formation of ROS. Moreover, TfR1-dependent uptake of transferrin was revealed to augment the formation of DNA-DSBs in the presence of hydrogen peroxide, which served as a substrate for the Fenton reaction. An
ex vivo
study with murine fallopian tubes further demonstrated that transferrin treatment introduced DNA-DSBs in the fallopian tubal epithelium. Collectively, these data suggested that the transferrin-TfR1 axis accounts for the induction of DNA-DSBs that potentially lead to DNA damage/genome instability. These findings also suggested that exposure to transferrin initiates and promotes the development of ovarian cancer by aiding the accumulation of DNA-DSBs in the fallopian tubal epithelium.
Journal Article
Polyunsaturated fatty acid deficiency during neurodevelopment in mice models the prodromal state of schizophrenia through epigenetic changes in nuclear receptor genes
The risk of schizophrenia is increased in offspring whose mothers experience malnutrition during pregnancy. Polyunsaturated fatty acids (PUFAs) are dietary components that are crucial for the structural and functional integrity of neural cells, and PUFA deficiency has been shown to be a risk factor for schizophrenia. Here, we show that gestational and early postnatal dietary deprivation of two PUFAs—arachidonic acid (AA) and docosahexaenoic acid (DHA)—elicited schizophrenia-like phenotypes in mouse offspring at adulthood. In the PUFA-deprived mouse group, we observed lower motivation and higher sensitivity to a hallucinogenic drug resembling the prodromal symptoms in schizophrenia. Furthermore, a working-memory task-evoked hyper-neuronal activity in the medial prefrontal cortex was also observed, along with the downregulation of genes in the prefrontal cortex involved in oligodendrocyte integrity and the gamma-aminobutyric acid (GABA)-ergic system. Regulation of these genes was mediated by the nuclear receptor genes
Rxr
and
Ppar
, whose promoters were hyper-methylated by the deprivation of dietary AA and DHA. In addition, the RXR agonist bexarotene upregulated oligodendrocyte- and GABA-related gene expression and suppressed the sensitivity of mice to the hallucinogenic drug. Notably, the expression of these nuclear receptor genes were also downregulated in hair-follicle cells from schizophrenia patients. These results suggest that PUFA deficiency during the early neurodevelopmental period in mice could model the prodromal state of schizophrenia through changes in the epigenetic regulation of nuclear receptor genes.
Journal Article
Analysis of induced pluripotent stem cells carrying 22q11.2 deletion
by
Toyota, T
,
Sugiyama, S
,
Iwayama, Y
in
22q11 Deletion Syndrome - genetics
,
22q11 Deletion Syndrome - pathology
,
45/61
2016
Given the complexity and heterogeneity of the genomic architecture underlying schizophrenia, molecular analyses of these patients with defined and large effect-size genomic defects could provide valuable clues. We established human-induced pluripotent stem cells from two schizophrenia patients with the 22q11.2 deletion (two cell lines from each subject, total of four cell lines) and three controls (total of four cell lines). Neurosphere size, neural differentiation efficiency, neurite outgrowth, cellular migration and the neurogenic-to-gliogenic competence ratio were significantly reduced in patient-derived cells. As an underlying mechanism, we focused on the role of
DGCR8
, a key gene for microRNA (miRNA) processing and mapped in the deleted region. In mice,
Dgcr8
hetero-knockout is known to show a similar phenotype of reduced neurosphere size (Ouchi
et al.
, 2013). The miRNA profiling detected reduced expression levels of miRNAs belonging to miR-17/92 cluster and miR-106a/b in the patient-derived neurospheres. Those miRNAs are reported to target p38α, and conformingly the levels of p38α were upregulated in the patient-derived cells. p38α is known to drive gliogenic differentiation. The inhibition of p38 activity by SB203580 in patient-derived neurospheres partially restored neurogenic competence. Furthermore, we detected elevated expression of
GFAP
, a gliogenic (astrocyte) marker, in postmortem brains from schizophrenia patients without the 22q11.2 deletion, whereas inflammation markers (
IL1B
and
IL6
) remained unchanged. In contrast, a neuronal marker,
MAP2
expressions were decreased in schizophrenia brains. These results suggest that a dysregulated balance of neurogenic-to-gliogenic competence may underlie neurodevelopmental disorders such as schizophrenia.
Journal Article
Ceramide limits phosphatidylinositol-3-kinase C2β-controlled cell motility in ovarian cancer: potential of ceramide as a metastasis-suppressor lipid
2016
Targeting cell motility, which is required for dissemination and metastasis, has therapeutic potential for ovarian cancer metastasis, and regulatory mechanisms of cell motility need to be uncovered for developing novel therapeutics. Invasive ovarian cancer cells spontaneously formed protrusions, such as lamellipodia, which are required for generating locomotive force in cell motility. Short interfering RNA screening identified class II phosphatidylinositol 3-kinase C2β (PI3KC2β) as the predominant isoform of PI3K involved in lamellipodia formation of ovarian cancer cells. The bioactive sphingolipid ceramide has emerged as an antitumorigenic lipid, and treatment with short-chain C
6
-ceramide decreased the number of ovarian cancer cells with PI3KC2β-driven lamellipodia. Pharmacological analysis demonstrated that long-chain ceramide regenerated from C
6
-ceramide through the salvage/recycling pathway, at least in part, mediated the action of C
6
-ceramide. Mechanistically, ceramide was revealed to interact with the PIK-catalytic domain of PI3KC2β and affect its compartmentalization, thereby suppressing PI3KC2β activation and its driven cell motility. Ceramide treatment also suppressed cell motility promoted by epithelial growth factor, which is a prometastatic factor. To examine the role of ceramide in ovarian cancer metastasis, ceramide liposomes were employed and confirmed to suppress cell motility
in vitro
. Ceramide liposomes had an inhibitory effect on peritoneal metastasis in a murine xenograft model of human ovarian cancer. Metastasis of PI3KC2β knocked-down cells was insensitive to treatment with ceramide liposomes, suggesting specific involvement of ceramide interaction with PI3KC2β in metastasis suppression. Our study identified ceramide as a bioactive lipid that limits PI3KC2β-governed cell motility, and ceramide is proposed to serve as a metastasis-suppressor lipid in ovarian cancer. These findings could be translated into developing ceramide-based therapy for metastatic diseases.
Journal Article
22q11.2 deletion carriers and schizophrenia-associated novel variants
by
Toyota, T.
,
Balan, S.
,
Yoshikawa, T.
in
Adult
,
Adult and adolescent clinical studies
,
Biological and medical sciences
2014
The penetrance of schizophrenia risk in carriers of the 22q11.2 deletion is high but incomplete, suggesting the possibility of additional genetic defects. We performed whole exome sequencing on two individuals with 22q11.2 deletion, one with schizophrenia and the other who was psychosisfree. The results revealed novel genetic variants related to neuronal function exclusively in the person with schizophrenia (frameshift: KAT8, APOH and SNX31; nonsense: EFCAB11 and CLVS2). This study paves the way towards a more complete understanding of variant dose and genetic architecture in schizophrenia.
Journal Article
Effect of PD-1 inhibitor on exhaled nitric oxide and pulmonary function in non-small cell lung cancer patients with and without COPD
2019
Nivolumab, a programmed death 1 (PD-1) immune checkpoint inhibitor, has been shown to improve survival in non-small cell lung cancer (NSCLC). The possible involvement of PD-1 axis in the pathogenesis of inflammatory lung disease, such as chronic obstructive pulmonary disease (COPD) has also been reported. However, effects of PD-1 blockade on the respiratory system remain unknown.
This prospective study aimed to investigate whether inhibition of the PD-1 axis altered lung inflammation and pulmonary function in NSCLC patients with and without COPD.
This was a prospective multi-center study. Measurements of fractioned exhaled nitric oxide (FeNO) and pulmonary function were performed before and after 4 cycles of nivolumab therapy.
A total of 137 patients with NSCLC were initially enrolled, and subsequently 95 patients (41 COPD and 54 non-COPD) receiving 4 cycles of nivolumab administration were included. After anti-PD-1 therapy, FeNO levels were significantly elevated together with increase in peripheral eosinophils. Interestingly, significant FeNO elevation was only found in COPD patients without increased peripheral eosinophils, but this was not the case in non-COPD patients. Additionally, COPD patients exhibited significant increases in FVC and FEV
but no changes in dyspnea scales, and acute exacerbation did not occur during the therapy.
Our observations suggest that anti-PD-1 therapy changed FeNO levels and pulmonary function in NSCLC patients. This therapy does not worsen COPD in terms of symptoms, pulmonary function, or acute exacerbation.
Journal Article
p21 provides stage specific DNA damage control to preimplantation embryos
2007
The early stage embryogenesis of higher eukaryotes lacks some of the damage response pathways such as G1/S checkpoint, G2/M checkpoint and apoptosis. We examined here the damage response of preimplantation stage embryos after fertilization with 6 Gy irradiated sperm. Sperm-irradiated embryos developed normally for the first 2.5 days, but started to exhibit a developmental delay at day 3.5. p21 was activated in the delayed embryos, which carried numerous micronuclei owing to delayed chromosome instability. Apoptosis was observed predominantly in the inner cell mass of the day 4.0 embryos. Sperm-irradiated p21−/− embryos lacked the delay, but chromosome instability and apoptosis were more pronounced than the corresponding p21 wild-type embryos. We conclude from the result that damage responses come in a stage-specific manner during preimplantation stage development; p53-dependent S checkpoint at the zygote stage, p21-mediated cell cycle arrest at the morula/blastocyst stages and apoptosis after the blastocyst stage in the inner cell mass.
Journal Article
Preserving tardigrades under pressure
1998
When an animal is exposed to high hydrostatic pressure, its cellular membranes
1
,
2
, proteins
3
,
4
,
5
and DNA
6
are damaged. At pressures of around 30 megapascals (MPa), proliferation and metabolism in micro-organisms stops; at 300 MPa, most bacteria and multicellular organisms die. But here we show that, in perfluorocarbon at pressures as high as 600 MPa, small terrestrial animals known as tardigrades can survive in a dehydrated state.
Journal Article
Effects of indacaterol versus tiotropium on respiratory mechanics assessed by the forced oscillation technique in patients with chronic obstructive pulmonary disease
by
Inui, Naoki
,
Nakamura, Yutaro
,
Toyoshima, Mikio
in
Adrenergic beta-2 Receptor Agonists - adverse effects
,
Adrenergic beta-2 Receptor Agonists - therapeutic use
,
Aged
2015
The forced oscillation technique (FOT) can measure respiratory mechanics and has attracted attention in chronic obstructive pulmonary disease (COPD). We aimed to evaluate the effects of only indacaterol and tiotropium monotherapies on airflow limitation and respiratory impedance. Pulmonary function tests, COPD assessment test (CAT), and multifrequency FOT with MostGraph-01 were performed at the beginning and after 8 weeks of treatment with indacaterol or tiotropium. The resistance index, resistance at 5 Hz (R5), resistance at 20 Hz (R20), reactance index, reactance at 5 Hz (X5), resonant frequency (Fres), and low-frequency reactance area (ALX) were determined at whole-breath, inspiratory, and expiratory phases. Eighty-two patients (mean age: 73 years; mean forced expiratory volume in 1 second (FEV1): 61.6%±19.0% predicted) were randomized to indacaterol or tiotropium treatment. Both bronchodilators improved airflow limitation, with mean trough improvements in FEV1 of 165 mL and 80 mL in the indacaterol and tiotropium groups, respectively. The CAT score decreased in the indacaterol group (P<0.001; 11.2±6.6 to 7.5±5.6). Compared with tiotropium, indacaterol significantly improved FEV1, percent predicted FEV1, and CAT score (P=0.042, P=0.008, and P=0.027, respectively). For respiratory impedance, indacaterol and tiotropium changed R5, X5, Fres, and ALX at whole-breath, inspiratory, and expiratory phases. In the indacaterol group, the changes in R5, R5-R20, X5, Fres, and ALX were significantly correlated with the changes in FEV1. The use of the FOT may enable the evaluation of the effects of bronchodilators in addition to FEV1-indicated therapeutic effects in COPD.
Journal Article
Chromosome Aberrations do not Persist in the Lymphocytes or Bone Marrow Cells of Mice Irradiated In Utero or Soon after Birth
2007
Nakano, M., Kodama, Y., Ohtaki, K., Nakashima, E., Niwa, O., Toyoshima, M. and Nakamura, N. Chromosome Aberrations do not Persist in the Lymphocytes or Bone Marrow Cells of Mice Irradiated In Utero or Soon after Birth. Radiat. Res. 167, 693–702 (2007). Mice were exposed at various ages to 1 Gy or 2 Gy of X rays, and translocation frequencies in peripheral blood T cells, spleen cells, and bone marrow cells were determined with FISH painting of chromosomes 1 and 3 when the animals were 20 weeks old. It was found that the mean translocation frequencies were very low (≤0.8%) in mice exposed in the fetal or early postnatal stages. However, with the increase in animal age at the time of irradiation, the frequency observed at 20 weeks old became progressively higher then reached a plateau (about 5%) when mice were irradiated when ≥6 weeks old. A major role of p53 (Trp53)-dependent apoptosis for elimination of aberrant cells was not suggested because irradiated fetuses, regardless of the p53 gene status, showed low translocation frequencies (1.8% in p53−/− mice and 1.4% in p53+/− mice) compared to the frequency in the p53−/− mother (7.4%). In contrast, various types of aberrations were seen in spleen and liver cells when neonates were examined shortly after irradiation, similar to what was observed in bone marrow cells after irradiation in adults. We interpreted the results as indicating that fetal cells are generally sensitive to induction of chromosome aberrations but that the aberrant cells do not persist because fetal stem cells tend to be free of aberrations and their progeny replace the pre-existing cell populations during the postnatal growth of the animals.
Journal Article