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Articles by H Ito
Total Records ( 7 ) for H Ito
  S Hirano , H Shinotoh , H Shimada , A Aotsuka , N Tanaka , T Ota , K Sato , H Ito , S Kuwabara , K Fukushi , T Irie and T. Suhara
 

Corticobasal syndrome, progressive supranuclear palsy and frontotemporal dementia are all part of a disease spectrum that includes common cognitive impairment and movement disorders. The aim of this study was to characterize brain cholinergic deficits in these disorders. We measured brain acetylcholinesterase activity by [11C] N-methylpiperidin-4-yl acetate and positron emission tomography in seven patients with corticobasal syndrome (67.6 ± 5.9 years), 12 with progressive supranuclear palsy (68.5 ± 4.1 years), eight with frontotemporal dementia (59.8 ± 6.9 years) and 16 healthy controls (61.2 ± 8.5 years). Two-tissue compartment three-parameter model and non-linear least squares analysis with arterial input function were performed. k3 value, an index of acetylcholinesterase activity, was calculated voxel-by-voxel in the brain of each subject. The k3 images in each disease group were compared with the control group by using Statistical Parametric Mapping 2. Volume of interest analysis was performed on spatially normalized k3 images. The corticobasal syndrome group showed decreased acetylcholinesterase activity (k3 values) in the paracentral region, frontal, parietal and occipital cortices (P < 0.05, cluster corrected). The group with progressive supranuclear palsy had reduced acetylcholinesterase activity in the paracentral region and thalamus (P < 0.05, cluster corrected). The frontotemporal dementia group showed no significant differences in acetylcholinesterase activity. Volume of interest analysis showed mean cortical acetylcholinesterase activity to be reduced by 17.5% in corticobasal syndrome (P < 0.001), 9.4% in progressive supranuclear palsy (P < 0.05) and 4.4% in frontotemporal dementia (non-significant), when compared with the control group. Thalamic acetylcholinesterase activity was reduced by 6.4% in corticobasal syndrome (non-significant), 24.0% in progressive supranuclear palsy (P < 0.03) and increased by 3.3% in frontotemporal dementia (non-significant). Both corticobasal syndrome and progressive supranuclear palsy showed brain cholinergic deficits, but their distribution differed somewhat. Significant brain cholinergic deficits were not seen in frontotemporal dementia, which may explain the unresponsiveness of this condition to cholinergic modulation therapy.

  J. Y Park , K Matsuo , T Suzuki , H Ito , S Hosono , T Kawase , M Watanabe , I Oze , T Hida , Y Yatabe , T Mitsudomi , T Takezaki , K Tajima and H. Tanaka
 

The main lifestyle contributor to acetaldehyde exposure is the drinking of alcoholic beverages, but tobacco smoke also makes some contribution. Although acetaldehyde is associated with upper aerodigestive tract cancer risk, in accordance with genetically determined acetaldehyde metabolism, it is unclear whether lung cancer, a representative smoking-related cancer, is associated with acetaldehyde or genes impacting its metabolism. We conducted a case–control study to examine possible interaction between smoking and aldehyde dehydrogenase 2 (ALDH2) Glu504Lys polymorphism (rs671) on the risk of lung cancer in Japanese. Subjects were 718 lung cancer cases and 1416 non-cancer controls enrolled in the Hospital-based Epidemiologic Research Program at Aichi Cancer Center. Lifestyle factors, including smoking, were determined by self-administered questionnaire. We applied pack-years (PY; categorized into five levels: never, <15, <30, <45 and ≥45) as a marker of cumulative exposure to smoking. The impact of smoking, ALDH2 genotype, and their interaction on lung cancer risk were assessed by odds ratio (OR) and 95% confidence interval adjusted for potential confounders. Adjusted ORs for PY <15, <30, <45 and ≥45 relative to never smokers among those with Glu/Glu or Glu/Lys were 1.39, 1.80, 3.44 and 6.25, respectively (P-trend = 1.4 x 10–30). In contrast, ORs among Lys/Lys were 1.01, 10.2, 11.4 and 23.2, respectively (P-trend = 2.6 x 10–7). Interaction between ALDH2 genotype (Glu/Glu + Glu/Lys versus Lys/Lys) and cumulative smoking dose was statistically significant (P = 0.036) and was consistently observed in the analysis among never-drinkers (interaction P = 0.041). These results suggest that ALDH2 Lys/Lys, a null enzyme activity genotype, modifies the impact of smoking on the risk of lung cancer.

  J Endo , M Sano , T Katayama , T Hishiki , K Shinmura , S Morizane , T Matsuhashi , Y Katsumata , Y Zhang , H Ito , Y Nagahata , S Marchitti , K Nishimaki , A. M Wolf , H Nakanishi , F Hattori , V Vasiliou , T Adachi , I Ohsawa , R Taguchi , Y Hirabayashi , S Ohta , M Suematsu , S Ogawa and K. Fukuda
 

Rationale: Aldehyde accumulation is regarded as a pathognomonic feature of oxidative stress–associated cardiovascular disease.

Objective: We investigated how the heart compensates for the accelerated accumulation of aldehydes.

Methods and Results: Aldehyde dehydrogenase 2 (ALDH2) has a major role in aldehyde detoxification in the mitochondria, a major source of aldehydes. Transgenic (Tg) mice carrying an Aldh2 gene with a single nucleotide polymorphism (Aldh2*2) were developed. This polymorphism has a dominant-negative effect and the Tg mice exhibited impaired ALDH activity against a broad range of aldehydes. Despite a shift toward the oxidative state in mitochondrial matrices, Aldh2*2 Tg hearts displayed normal left ventricular function by echocardiography and, because of metabolic remodeling, an unexpected tolerance to oxidative stress induced by ischemia/reperfusion injury. Mitochondrial aldehyde stress stimulated eukaryotic translation initiation factor 2 phosphorylation. Subsequent translational and transcriptional activation of activating transcription factor-4 promoted the expression of enzymes involved in amino acid biosynthesis and transport, ultimately providing precursor amino acids for glutathione biosynthesis. Intracellular glutathione levels were increased 1.37-fold in Aldh2*2 Tg hearts compared with wild-type controls. Heterozygous knockout of Atf4 blunted the increase in intracellular glutathione levels in Aldh2*2 Tg hearts, thereby attenuating the oxidative stress–resistant phenotype. Furthermore, glycolysis and NADPH generation via the pentose phosphate pathway were activated in Aldh2*2 Tg hearts. (NADPH is required for the recycling of oxidized glutathione.)

Conclusions: The findings of the present study indicate that mitochondrial aldehyde stress in the heart induces metabolic remodeling, leading to activation of the glutathione–redox cycle, which confers resistance against acute oxidative stress induced by ischemia/reperfusion.

  E Tahara , W Yasui , H Ito and C. C. Harris
 

This symposium presented recent progress of the pathogenesis and treatment of lung cancer. Aberrantly increased expression of miR-21 plays a significant role in lung carcinogenesis and is a potential therapeutic target in both epidermal growth factor receptor-mutant and wild-type cases. miR-34 may be necessary for the radiation-induced DNA damage response. Detailed expression profiling analyses of transcriptome have potential to provide increased understanding of the molecular biology of lung cancer. An embryonic signature is present in lung adenocarcinoma only, associated with a worse clinical outcome. Cytoplasmic expression of caveolin and membranous expression of CD26 are specific to mesothelioma. Nectin-4 is a new candidate for serum and tissue biomarker as well as a therapeutic target for lung cancer. Clinical presentations have provided us a great deal information on epidermal growth factor receptor mutations for personalized therapy, combination therapy with inhibitors of the tyrosine kinase activity of epidermal growth factor receptor and cytotoxic agents, antibody-dependent cellular cytotoxicity activity, and current management of lung cancer depending on both the extent of the disease and the treatment approach.

  Y Horie , H Ito , M Kusaba , R Tanaka and A. Tanaka
 

The light-harvesting chlorophyll a/b-protein complex of photosystem II (LHCII) is the most abundant membrane protein in green plants, and its degradation is a crucial process for the acclimation to high light conditions and for the recovery of nitrogen (N) and carbon (C) during senescence. However, the molecular mechanism of LHCII degradation is largely unknown. Here, we report that chlorophyll b reductase, which catalyzes the first step of chlorophyll b degradation, plays a central role in LHCII degradation. When the genes for chlorophyll b reductases NOL and NYC1 were disrupted in Arabidopsis thaliana, chlorophyll b and LHCII were not degraded during senescence, whereas other pigment complexes completely disappeared. When purified trimeric LHCII was incubated with recombinant chlorophyll b reductase (NOL), expressed in Escherichia coli, the chlorophyll b in LHCII was converted to 7-hydroxymethyl chlorophyll a. Accompanying this conversion, chlorophylls were released from LHCII apoproteins until all the chlorophyll molecules in LHCII dissociated from the complexes. Chlorophyll-depleted LHCII apoproteins did not dissociate into monomeric forms but remained in the trimeric form. Based on these results, we propose the novel hypothesis that chlorophyll b reductase catalyzes the initial step of LHCII degradation, and that trimeric LHCII is a substrate of LHCII degradation.

  M Yamamoto , D. M Standley , S Takashima , H Saiga , M Okuyama , H Kayama , E Kubo , H Ito , M Takaura , T Matsuda , D Soldati Favre and K. Takeda
 

Infection by Toxoplasma gondii down-regulates the host innate immune responses, such as proinflammatory cytokine production, in a Stat3-dependent manner. A forward genetic approach recently demonstrated that the type II strain fails to suppress immune responses because of a potential defect in a highly polymorphic parasite-derived kinase, ROP16. We generated ROP16-deficient type I parasites by reverse genetics and found a severe defect in parasite-induced Stat3 activation, culminating in enhanced production of interleukin (IL) 6 and IL-12 p40 in the infected macrophages. Furthermore, overexpression of ROP16 but not ROP18 in mammalian cells resulted in Stat3 phosphorylation and strong activation of Stat3-dependent promoters. In addition, kinase-inactive ROP16 failed to activate Stat3. Comparison of type I and type II ROP16 revealed that a single amino acid substitution in the kinase domain determined the strain difference in terms of Stat3 activation. Moreover, ROP16 bound Stat3 and directly induced phosphorylation of this transcription factor. These results formally establish an essential and direct requirement of ROP16 in parasite-induced Stat3 activation and the significance of a single amino acid replacement in the function of type II ROP16.

 
 
 
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