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Search Results: 1 - 10 of 679 matches for " Kazuya Terasawa "
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Synthetic Pre-miRNA-Based shRNA as Potent RNAi Triggers
Kazuya Terasawa,Kazuharu Shimizu,Gozoh Tsujimoto
Journal of Nucleic Acids , 2011, DOI: 10.4061/2011/131579
Abstract: RNA interference (RNAi) is a powerful tool for studying gene function owing to the ease with which it can selectively silence genes of interest, and it has also attracted attention because of its potential for therapeutic applications. Chemically synthesized small interfering RNAs (siRNAs) and DNA vector-based short hairpin RNAs (shRNAs) are now widely used as RNAi triggers. In contrast to expressed shRNAs, the use of synthetic shRNAs is limited. Here we designed shRNAs modeled on a precursor microRNA (pre-miRNA) and evaluated their biological activity. We demonstrated that chemically synthetic pre-miRNA-based shRNAs have more potent RNAi activity than their corresponding siRNAs and found that their antisense strands are more efficiently incorporated into the RNA-induced silencing complex. Although greater off-target effects and interferon responses were induced by shRNAs than by their corresponding siRNAs, these effects could be overcome by simply using a lower concentration or by optimizing and chemically modifying shRNAs similar to synthetic siRNAs. These are challenges for the future. 1. Introduction RNA interference (RNAi) is an evolutionarily conserved, gene-silencing mechanism that is triggered by double-stranded RNA (dsRNA). Two types of small RNA—namely, small interfering RNA (siRNA) and microRNA (miRNA)—are central players in RNAi. Both siRNAs and miRNAs regulate gene expression by annealing to mRNA sequence elements that are fully or partially complementary [1, 2]. Since transfected synthetic siRNAs were shown to induce RNAi in mammalian cells [3], they have been widely used to decipher gene function through suppression of gene expression, and they have also attracted attention because of their potential for therapeutic applications [4, 5]. miRNAs are a phylogenetically conserved family of endogenous small RNAs that play important roles in a wide variety of biological functions, including cell differentiation, tumor genesis, apoptosis, and metabolism [1, 2, 6, 7]. miRNAs are initially generated as long primary transcripts (pri-miRNA) that are processed in the nucleus by the enzyme complexes Drosha and DiGeorge Critical Region 8 (DGCR8) to a 70–90?nt stem-loop structure called pre-miRNA. The pre-miRNA is then exported to the cytoplasm. There, the exported pre-miRNA or exogenous dsRNA is cleaved by the enzyme Dicer into a ~22-nucleotide (nt) duplex known as miRNA or siRNA, respectively. The duplex is then incorporated into the RNA-induced silencing complex (RISC). After removing one strand called the passenger strand, the remaining strand,
Intra-Platform Repeatability and Inter-Platform Comparability of MicroRNA Microarray Technology
Fumiaki Sato, Soken Tsuchiya, Kazuya Terasawa, Gozoh Tsujimoto
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005540
Abstract: Over the last decade, DNA microarray technology has provided a great contribution to the life sciences. The MicroArray Quality Control (MAQC) project demonstrated the way to analyze the expression microarray. Recently, microarray technology has been utilized to analyze a comprehensive microRNA expression profiling. Currently, several platforms of microRNA microarray chips are commercially available. Thus, we compared repeatability and comparability of five different microRNA microarray platforms (Agilent, Ambion, Exiqon, Invitrogen and Toray) using 309 microRNAs probes, and the Taqman microRNA system using 142 microRNA probes. This study demonstrated that microRNA microarray has high intra-platform repeatability and comparability to quantitative RT-PCR of microRNA. Among the five platforms, Agilent and Toray array showed relatively better performances than the others. However, the current lineup of commercially available microRNA microarray systems fails to show good inter-platform concordance, probably because of lack of an adequate normalization method and severe divergence in stringency of detection call criteria between different platforms. This study provided the basic information about the performance and the problems specific to the current microRNA microarray systems.
Trastuzumab Produces Therapeutic Actions by Upregulating miR-26a and miR-30b in Breast Cancer Cells
Takehiro Ichikawa, Fumiaki Sato, Kazuya Terasawa, Soken Tsuchiya, Masakazu Toi, Gozoh Tsujimoto, Kazuharu Shimizu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031422
Abstract: Objective Trastuzumab has been used for the treatment of HER2-positive breast cancer (BC). However, a subset of BC patients exhibited resistance to trastuzumab therapy. Thus, clarifying the molecular mechanism of trastuzumab treatment will be beneficial to improve the treatment of HER2-positive BC patients. In this study, we identified trastuzumab-responsive microRNAs that are involved in the therapeutic effects of trastuzumab. Methods and Results RNA samples were obtained from HER2-positive (SKBR3 and BT474) and HER2-negetive (MCF7 and MDA-MB-231) cells with and without trastuzumab treatment for 6 days. Next, we conducted a microRNA profiling analysis using these samples to screen those microRNAs that were up- or down-regulated only in HER2-positive cells. This analysis identified miR-26a and miR-30b as trastuzumab-inducible microRNAs. Transfecting miR-26a and miR-30b induced cell growth suppression in the BC cells by 40% and 32%, respectively. A cell cycle analysis showed that these microRNAs induced G1 arrest in HER2-positive BC cells as trastuzumab did. An Annexin-V assay revealed that miR-26a but not miR-30b induced apoptosis in HER2-positive BC cells. Using the prediction algorithms for microRNA targets, we identified cyclin E2 (CCNE2) as a target gene of miR-30b. A luciferase-based reporter assay demonstrated that miR-30b post-transcriptionally reduced 27% (p = 0.005) of the gene expression by interacting with two binding sites in the 3′-UTR of CCNE2. Conclusion In BC cells, trastuzumab modulated the expression of a subset of microRNAs, including miR-26a and miR-30b. The upregulation of miR-30b by trastuzumab may play a biological role in trastuzumab-induced cell growth inhibition by targeting CCNE2.
Outer measures and weak type ( 1 , 1 ) estimates of Hardy-Littlewood maximal operators
Yutaka Terasawa
Journal of Inequalities and Applications , 2006,
Abstract: We will introduce the k times modified centered and uncentered Hardy-Littlewood maximal operators on nonhomogeneous spaces for k > 0 . We will prove that the k times modified centered Hardy-Littlewood maximal operator is weak type ( 1 , 1 ) bounded with constant 1 when k ≥ 2 if the Radon measure of the space has “continuity” in some sense. In the proof, we will use the outer measure associated with the Radon measure. We will also prove other results of Hardy-Littlewood maximal operators on homogeneous spaces and on the real line by using outer measures.
Outer measures and weak type estimates of Hardy-Littlewood maximal operators
Terasawa Yutaka
Journal of Inequalities and Applications , 2006,
Abstract: We will introduce the times modified centered and uncentered Hardy-Littlewood maximal operators on nonhomogeneous spaces for . We will prove that the times modified centered Hardy-Littlewood maximal operator is weak type bounded with constant when if the Radon measure of the space has "continuity" in some sense. In the proof, we will use the outer measure associated with the Radon measure. We will also prove other results of Hardy-Littlewood maximal operators on homogeneous spaces and on the real line by using outer measures.
Evidence-Based Reconstruction of Kampo Medicine: Part II—The Concept of Sho
Katsutoshi Terasawa
Evidence-Based Complementary and Alternative Medicine , 2004, DOI: 10.1093/ecam/neh022
Abstract:
Evidence-based Reconstruction of Kampo Medicine: Part I—Is Kampo CAM?
Katsutoshi Terasawa
Evidence-Based Complementary and Alternative Medicine , 2004, DOI: 10.1093/ecam/neh003
Abstract:
Evidence-based Reconstruction of Kampo Medicine: Part-III—How Should Kampo be Evaluated?
Katsutoshi Terasawa
Evidence-Based Complementary and Alternative Medicine , 2004, DOI: 10.1093/ecam/neh046
Abstract:
Publickey encryption by ordering
Yoshihiro Terasawa
Computer Science , 2014,
Abstract: In 1999, public key cryptography using the matrix was devised by a hish school student of 16 yesrs old girl Sarah Flannery. This cryptosystem seemed faster than RSA, and it's having the strength to surpass even the encryption to RSA. However, this encryption scheme was broken bfore har papers were published. In this paper, We try to construct publickey encryption scheme from permutation group that is equivalent to matrix as noncommutative group. And we explore the potential of this cryptsystem through implementation.
A Simple construction of the Pseudorandom Generator from Permutation
Yoshihiro Terasawa
Computer Science , 2014,
Abstract: A simple construction of pseudorandom generator is appear.This pseudorandom generator is always passed by NIST statistical test.This paper reports a pseudorandom number generator which has good property is able to construct using only permutation and data rewriting by XOR.
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