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991.
992.
Munesue S Yoshitomi Y Kusano Y Koyama Y Nishiyama A Nakanishi H Miyazaki K Ishimaru T Miyaura S Okayama M Oguri K 《The Journal of biological chemistry》2007,282(38):28164-28174
The syndecans comprise a family of cell surface heparan sulfate proteoglycans exhibiting complex biological functions involving the interaction of heparan sulfate side chains with a variety of soluble and insoluble heparin-binding extracellular ligands. Here we demonstrate an inverse correlation between the expression level of syndecan-2 and the metastatic potential of three clones derived from Lewis lung carcinoma 3LL. This correlation was proved to be a causal relationship, because transfection of syndecan-2 into the higher metastatic clone resulted in the suppression of both spontaneous and experimental metastases to the lung. Although the expression levels of matrix metalloproteinase-2 (MMP-2) and its cell surface activators, such as membrane-type 1 matrix metalloproteinase and tissue inhibitor of metalloproteinase-2, were similar regardless of the metastatic potentials of the clones, elevated activation of MMP-2 was observed in the higher metastatic clone. Removal of heparan sulfate from the cell surface of low metastatic cells by treatment with heparitinase-I promoted MMP-2 activation, and transfection of syndecan-2 into highly metastatic cells suppressed MMP-2 activation. Furthermore, transfection of mutated syndecan-2 lacking glycosaminoglycan attachment sites into highly metastatic cells did not have any suppressive effect on MMP-2 activation, suggesting that this suppression was mediated by the heparan sulfate side chains of syndecan-2. Actually, MMP-2 was found to exhibit a strong binding ability to heparin, the dissociation constant value being 62 nM. These results indicate a novel function of syndecan-2, which acts as a suppressor for MMP-2 activation, causing suppression of metastasis in at least the metastatic system used in the present study. 相似文献
993.
It is important that task performance is physiologically evaluated in consideration of arousal level. But there are relatively few preceding studies. In this study, the relationship between task performance and physiological indices was studied with regard to attentiveness concentration. The subjects were eight healthy college students. They performed calculations and a visual display terminal (VDT) task. Electroencephalogram (EEG) frequency component, alpha attenuation coefficient (AAC), skin potential level (SPL), blood flow of the finger tip skin (BF), and visual analog scale (VAS), were measured. In order to quantify task performance, correlations between the task performance and physiological indices during the mental task were analyzed. The results suggest that AAC correlates with the error rate in calculation. BF also correlates with the error rate in calculation, while the calculation speed correlates with SPL. It can be inferred that the task speed and error rate are supposed to be related to the different physiological background. 相似文献
994.
Yamagishi S Koyama Y Katayama T Taniguchi M Hitomi J Kato M Aoki M Itoyama Y Kato S Tohyama M 《PloS one》2007,2(10):e1030
Neuronal Lewy body-like hyaline inclusions (LBHI) and astrocytic hyaline inclusions (Ast-HI) containing mutant Cu/Zn superoxide dismutase 1 (SOD1) are morphological hallmarks of familial amyotrophic lateral sclerosis (FALS) associated with mutant SOD1. However, the mechanisms by which mutant SOD1 contributes to formation of LBHI/Ast-HI in FALS remain poorly defined. Here, we report induction of LBHI/Ast-HI-like hyaline inclusions (LHIs) in vitro by ER stress in neuroblastoma cells. These LHI closely resemble LBHI/Ast-HI in patients with SOD1-linked FALS. LHI and LBHI/Ast-HI share the following features: 1) eosinophilic staining with a pale core, 2) SOD1, ubiquitin and ER resident protein (KDEL) positivity and 3) the presence of approximately 15-25 nm granule-coated fibrils, which are morphological hallmark of mutant SOD1-linked FALS. Moreover, in spinal cord neurons of L84V SOD1 transgenic mice at presymptomatic stage, we observed aberrant aggregation of ER and numerous free ribosomes associated with abnormal inclusion-like structures, presumably early stage neuronal LBHI. We conclude that the LBHI/Ast-HI seen in human patients with mutant SOD1-linked FALS may arise from ER dysfunction. 相似文献
995.
996.
Isao Ebina Mariko Takemoto-Tsutsumi Shun Watanabe Hiroaki Koyama Yayoi Endo Kaori Kimata Takuya Igarashi Karin Murakami Rin Kudo Arisa Ohsumi Abdul Latif Noh Hiro Takahashi Satoshi Naito Hitoshi Onouchi 《Nucleic acids research》2015,43(3):1562-1576
Upstream open reading frames (uORFs) are often found in the 5′-leader regions of eukaryotic mRNAs and can negatively modulate the translational efficiency of the downstream main ORF. Although the effects of most uORFs are thought to be independent of their encoded peptide sequences, certain uORFs control translation of the main ORF in a peptide sequence-dependent manner. For genome-wide identification of such peptide sequence-dependent regulatory uORFs, exhaustive searches for uORFs with conserved amino acid sequences have been conducted using bioinformatic analyses. However, whether the conserved uORFs identified by these bioinformatic approaches encode regulatory peptides has not been experimentally determined. Here we analyzed 16 recently identified Arabidopsis thaliana conserved uORFs for the effects of their amino acid sequences on the expression of the main ORF using a transient expression assay. We identified five novel uORFs that repress main ORF expression in a peptide sequence-dependent manner. Mutational analysis revealed that, in four of them, the C-terminal region of the uORF-encoded peptide is critical for the repression of main ORF expression. Intriguingly, we also identified one exceptional sequence-dependent regulatory uORF, in which the stop codon position is not conserved and the C-terminal region is not important for the repression of main ORF expression. 相似文献
997.
Geographic body size variation in the periodical cicadas Magicicada: implications for life cycle divergence and local adaptation
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T. Koyama H. Ito S. Kakishima J. Yoshimura J. R. Cooley C. Simon T. Sota 《Journal of evolutionary biology》2015,28(6):1270-1277
Seven species in three species groups (Decim, Cassini and Decula) of periodical cicadas (Magicicada) occupy a wide latitudinal range in the eastern United States. To clarify how adult body size, a key trait affecting fitness, varies geographically with climate conditions and life cycle, we analysed the relationships of population mean head width to geographic variables (latitude, longitude, altitude), habitat annual mean temperature (AMT), life cycle and species differences. Within species, body size was larger in females than males and decreased with increasing latitude (and decreasing habitat AMT), following the converse Bergmann's rule. For the pair of recently diverged 13‐ and 17‐year species in each group, 13‐year cicadas were equal in size or slightly smaller on average than their 17‐year counterparts despite their shorter developmental time. This fact suggests that, under the same climatic conditions, 17‐year cicadas have lowered growth rates compared to their 13‐years counterparts, allowing 13‐year cicadas with faster growth rates to achieve body sizes equivalent to those of their 17‐year counterparts at the same locations. However, in the Decim group, which includes two 13‐year species, the more southerly, anciently diverged 13‐year species (Magicicada tredecim) was characterized by a larger body size than the other, more northerly 13‐ and 17‐year species, suggesting that local adaptation in warmer habitats may ultimately lead to evolution of larger body sizes. Our results demonstrate how geographic clines in body size may be maintained in sister species possessing different life cycles. 相似文献
998.
999.
Mizuki Takemoto Hideaki E. Kato Michio Koyama Jumpei Ito Motoshi Kamiya Shigehiko Hayashi Andrés D. Maturana Karl Deisseroth Ryuichiro Ishitani Osamu Nureki 《PloS one》2015,10(6)
Channelrhodopsin (ChR) is a light-gated cation channel that responds to blue light. Since ChR can be readily expressed in specific neurons to precisely control their activities by light, it has become a powerful tool in neuroscience. Although the recently solved crystal structure of a chimeric ChR, C1C2, provided the structural basis for ChR, our understanding of the molecular mechanism of ChR still remains limited. Here we performed electrophysiological analyses and all-atom molecular dynamics (MD) simulations, to investigate the importance of the intracellular and central constrictions of the ion conducting pore observed in the crystal structure of C1C2. Our electrophysiological analysis revealed that two glutamate residues, Glu122 and Glu129, in the intracellular and central constrictions, respectively, should be deprotonated in the photocycle. The simulation results suggested that the deprotonation of Glu129 in the central constriction leads to ion leakage in the ground state, and implied that the protonation of Glu129 is important for preventing ion leakage in the ground state. Moreover, we modeled the 13-cis retinal bound; i.e., activated C1C2, and performed MD simulations to investigate the conformational changes in the early stage of the photocycle. Our simulations suggested that retinal photoisomerization induces the conformational change toward channel opening, including the movements of TM6, TM7 and TM2. These insights into the dynamics of the ground states and the early photocycle stages enhance our understanding of the channel function of ChR. 相似文献
1000.