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Biomedical subjects

Makoto Koizumi

Publications and source records attributed to Makoto Koizumi.

At least 19 recordsLinked to original sources
PubMed2006

Comparison between properties of 2'-O,4'-C-ethylene-bridged nucleic acid (ENA) phosphorothioate oligonucleotides and N3'-P5' thiophosphoramidate oligonucleotides.

Synthesis and properties of an oligonucleotide uniformly modified with 2'-O,4-C-ethylene-bridged nucleic acid (ENA) units were compared with those of GRN163, which is modified with N3'-P5' thiophosphoramidates, with the sequence targeting human telomerase RNA subunit. Although an ENA phosphorothioate oligonucleotide, ENA-13, could be synthesized using ENA phosphoramidites on a 100-mg scale, synthesis of GRN163 was very hard even on a 1-micomol scale. In view of both stability of the duplex formation with complementary RNA and the efficiency of cellular uptake by endocytosis, ENA-13 was superior to GRN163. These findings suggest that ENA-13 has useful properties for antisense therapeutic application.

Chromatography, High Pressure Liquid↗
PubMed2006

Inhibition of VEGF mRNA by 2'-O,4'-C-ethylene-bridged nucleic acids (ENA) antisense oligonucleotides and their influence on off-target gene expressions.

We investigated 2'-O,4'-C-ethylene-bridged nucleic acids (ENA) antisense oligonucleotides (AONs) for vascular endothelial growth factor (VEGF) in human lung carcinoma A549 cells. An ENA/DNA gapmer AON with RNase H-mediated activity was virtually stable in rat plasma and exhibited more than 90% inhibition of VEGF mRNA production. Moreover, 22 genes that are likely to bind to the AON were found in the GenBank database by BLAST and CLUSTAL W searches. Three of these genes were actually inhibited by the ENA AON. In shorter ENA AONs with fewer matched sequences of these genes, inhibitiory activities were decreased and off-target effects were improved. These results indicate that ENA AONs act in a sequence-specific manner and could be used as effective antisense drugs.

Animals↗
PubMed2006

Direct comparison of in vivo antisense activity of ENA oligonucleotides targeting PTP1B mRNA with that of 2'-O-(2-methoxy)ethyl-modified oligonucleotides.

Protein-tyrosine phosphatase 1B (PTP1B) inhibitory activity of the 2'-O-(2-methoxy)ethyl (2'- MOE)-modified gapmer antisense oligonucleotide, ISIS113715, was previously reported. This antisense oligonucleotide increases insulin sensitivity and normalizes plasma glucose levels in diabetic ob/ob and db/db mice. In the present study, the isosequential 2'-O,4'-C-ethylene-bridged nucleic acid (ENA)-modified oligonucleotide, ENA-1, was synthesized, and its ability to further improve the downregulation of PTP1B in db/db mice was examined. We demonstrated that, compared with ISIS113715, intraperitoneal and subcutaneous administration of ENA-1 more effectively decreased the plasma glucose levels in db/db mice. Moreover, ENA-1 decreased expression of PTP1B in the liver and fat of db/db mice more effectively than ISIS113715. We describe for the first time the functional comparison of 2'-MOE- and ENA-modified antisense oligonucleotides. Our data indicate that the enhancement of the efficacy of antisense oligonucleotides by ENA modifications is superior to that of second-generation 2'-MOE modifications in certain aspects.

Animals↗
PubMed2006

Design of ENA gapmers as fine-tuning antisense oligonucleotides with sequence-specific inhibitory activity on mouse PADI4 mRNA expression.

In order to evaluate the function of the mouse peptidylarginine deiminase 4 (PADI4) gene, gapmer-designed ENA antisense oligonucleotides were utilized. Antisense ENA gapmers were found to inhibit the mRNA expression of the PADI4 gene, but ENA gapmers with sense sequences as controls only partially inhibited this mRNA expression. An in vitro E. coli RNase H reaction analysis using transcripts of the PADI4 gene and their ENA gapmers revealed that the mixtures of the transcripts and ENA gapmers with sense sequences were cleaved at non-target sites by RNase H derived from partial base-pairing between the transcript and the ENA gapmer. In an in vitro E. coli RNase H reaction analysis, when the DNA region of the ENA gapmer was shortened to 5 or 6 nucleotides, the non-target cleavage disappeared and the specific inhibition of PADI4 mRNA expression was observed. These results demonstrated that ENA gapmers with a short DNA region improved the sequence-specificity of mRNA down-regulation. As well, they suggest that we should be alert to the utility of antisense oligonucleotides with a wide DNA region in terms of sequence specificity, and additionally, that optimized ENA gapmers could be useful for application to gene validation.

Animals↗
PubMed2006

ENA oligonucleotides as therapeutics.

Oligonucleotides containing 2'-O,4'-C-ethylene-bridged nucleic acid (ENA) residues have two notable properties: (i) considerable affinity to complementary single-stranded RNA and double-stranded DNA; and (ii) dramatically high resistance against nucleases. On the basis of these properties, the in vitro and in vivo applications of ENA for gene silencing as antisense oligonucleotides, triplex-forming oligonucleotides and small interfering RNAs are discussed here. ENA oligonucleotides also have potential as therapeutic agents for Duchenne muscular dystrophy by a mechanism of exon skipping.

Animals↗
PubMed2005

Improvement of single nucleotide polymorphism genotyping by allele-specific PCR using primers modified with an ENA residue.

When we placed an ENA residue into primers at the 3' end, or the n-1, n-2, or n-3 position, which included a single nucleotide polymorphism (SNP) site at the 3' end, only primers containing the ENA residue at the n-2 position were read by Taq DNA polymerase for amplification. The use of the ENA primers avoided the generation of undesired short products, which are thought to be derived from primer-dimers. A greater discrimination of the SNP site by these primers containing the ENA residue was observed compared with that of the corresponding unmodified DNA primers that are often used for allele-specific polymerase chain reaction (AS-PCR). This improvement is probably due to the difficulty of incorporating a nucleotide into the mismatched ENA primer by Taq DNA polymerase in the modified primer-template duplex. These results demonstrate that ENA primer-based AS-PCR would enable a rapid and reliable technique for SNP genotyping.

Alleles↗
PubMed2005

Synthesis and properties of ENA oligonucleotides targeted to human telomerase RNA subunit.

Oligonucleotides uniformly modified with 2'-O,4'-C-ethylene-bridged nucleic acid (ENA) units were synthesized using the phosphoramidite method on a hundred-milligram scale for the evaluation of thermodynamic and chemical properties. The properties of these ENA oligonucleotides with the sequences targeted to human telomerase RNA subunit (hTR) were compared with those of GRN163, which is an oligonucleotide modified with N3'-P5' thiophosphoramidates. The melting temperatures of the duplexes of ENA oligonucleotides with complementary RNA were higher than that of the duplex of GRN163. Moreover, ENA oligonucleotide ENA-13 was more highly stable than GRN163 under acidic conditions (pH 5.0). ENA-13, which contained contiguous guanine sequences, could not form a G-quadruplex, which formation is not feasible for binding to hTR as an antisense molecule. The above findings suggest that ENA oligonucleotides may be useful for antisense therapeutic applications.

Humans↗
PubMed2005

SNP genotyping by allele-specific PCR using ENA primers.

When we placed a 2'-O,4'-C-ethylene nucleic acid (ENA) residue into primers at the 3' end, or the n-1, n-2 or n-3 position, which included a single nucleotide polymorphism (SNP) site at the 3' end, only primers containing the ENA residue at the n-2 position were read by Taq DNA polymerase for amplification. When we compared n-2-position-modified ENA with the corresponding unmodified DNA primers that are often used for allele-specific PCR (AS-PCR), a greater discrimination of the SNP site by ENA primers was observed. This improvement is probably due to the difficulty of incorporating a nucleotide into a mismatched ENA primer by Taq DNA polymerase in the primer-template duplex. These results demonstrate that ENA primer-based AS-PCR would enable a rapid and reliable technique for SNP genotyping.

Alleles↗
PubMed2004

Enhancement of the inhibitory activity of oatp antisense oligonucleotides by incorporation of 2'-O,4'-C-ethylene-bridged nucleic acids (ENA) without a loss of subtype selectivity.

Antisense oligonucleotides (AONs) that specifically target the genes of rat organic anion transporting polypeptide (oatp) subtypes were selected by using antisense in vitro selection (AIVS) and a conventional gene alignment program (GAP). When we incorporated several of our original 2'-O,4'-C-ethylene-bridged nucleic acid (ENA) residues into AONs, which were designed as gapmers containing a series of 2'-deoxynucleotides in the center, at both the 3' and 5' ends, the inhibitory activity of these oatp AONs was enhanced and their inhibition was mediated by RNase H cleavage. Moreover, these ENA AONs did not lose their oatp selectivity. These strategies of using AIVS and GAP to select AONs followed by incorporation of ENA residues were effective for synthesizing oatp subtype-specific AONs.

Animals↗
PubMed2004

Chimeric RNA/ethylene-bridged nucleic acids promote dystrophin expression in myocytes of duchenne muscular dystrophy by inducing skipping of the nonsense mutation-encoding exon.

Editing of dystrophin mRNA by induction of exon skipping, using antisense oligonucleotides, has been proposed as one way to generate dystrophin expression in Duchenne muscular dystrophy (DMD) patients. Here, antisense chimeric oligonucleotides consisting of RNA and a new modified nucleic acid are tested for activity to induce skipping of an exon containing a nonsense mutation. In a Japanese DMD case, a nonsense mutation (R1967X) due to a single nucleotide change in exon 41 of the dystrophin gene (C5899T) was identified. Oligonucleotides consisting of 2'-O-methyl RNA and a new 2'-O,4'-C-ethylene-bridged nucleic acid (ENA) were designed to bind the mutation site of exon 41, and their ability to induce exon 41 skipping in dystrophin mRNA was evaluated. Finally, among the specific oligonucleotides tested, an 18-mer RNA/ENA chimera was found to have the strongest activity, inducing exon 41 skipping in nearly 90% of dystrophin mRNA. Accordingly, nearly 90% of cultured myocytes were shown to be dystrophin positive by immunohistochemical analysis. Western blot analysis disclosed the presence of nearly normal-sized dystrophin up to 1 week after the transfection. Our results suggest that an RNA/ENA chimera can be used to express dystrophin in DMD.

Base Sequence↗
PubMed2004

Chimeric RNA and 2'-O, 4'-C-ethylene-bridged nucleic acids have stronger activity than phosphorothioate oligodeoxynucleotides in induction of exon 19 skipping in dystrophin mRNA.

Antisense phosphorothioate oligodeoxynucleotides against exon 19 of the dystrophin gene have been shown to induce exon 19 skipping and promote the expression of internally deleted dystrophin by correcting the translational reading frame. Because phosphorothioate oligonucleotides are associated with a variety of toxic nonantisense effects, several modifications of nucleic acid have been introduced to alleviate this toxicity. Recently, a 2'-O, 4'-C-ethylene-bridged nucleic acid (ENA trade mark, Sankyo Lifetech Co., Ltd., Tokyo, Japan) was reported to have high affinity to complementary RNA strands and be resistant to nuclease digestion. Here, we examined the ability of this modified nucleic acid to induce exon skipping. Oligonucleotides having the same sequence as the phosphorothioate oligonucleotides but with some stretches of modified backbone (2'-O-methyl RNA with an ENA5-mer at the 5'-end and 3'-end) (RNA/ENA chimera) were transfected into myocytes, and the expressed dystrophin mRNA was analyzed. The RNA/ENA chimera induced exon 19 skipping in a dose-dependent and time-dependent manner. Remarkably, the exon 19-skipping activity of the RNA/ENA chimera was more than 40 times stronger than that of the corresponding conventional phosphorothioate oligodeoxynucleotide. This is the first report of such strong activity of an RNA/ENA chimera in the induction of exon skipping in the dystrophin gene. This new technology will allow the development of less toxic antisense drugs, making long-term therapy possible.

Base Sequence↗
PubMed2004

Design of 2'-O-Me RNA/ENA chimera oligonucleotides to induce exon skipping in dystrophin pre-mRNA.

2'-O-Me RNA/ENA chimera oligonucleotides complementary to exon 45 and 46 of the dystrophin gene induced exon 45 and 46 skipping of the dystrophin pre-mRNA, respectively. The induction of exon skipping by the most effective 2'-O-Me RNA/ENA chimeras led to the expression of dystrophin in dystrophin-deficient myocytes by correcting the translational reading frames. Also, in the process of 2'-O-Me RNA/ENA chimera optimization to induce exon skipping in several exons, it was found that the optimized target sequences of the chimeras included guanosine- or adenosine-rich sequences that might function as spiking enhancer sequences (SES).

Adenosine↗
PubMed2004

2'-O,4'-C-ethylene-bridged nucleic acids (ENA) as next-generation antisense and antigene agents.

Novel 2'-O,4'-C-ethylene nucleosides have been synthesized as building blocks for antisense and antigene oligonucleotides. 2'-O,4'-C-Ethylene-bridged nucleic acids (ENA) comprising 2'-O,4'-C-ethylene nucleosides have considerable affinity to complementary RNA and double-stranded DNA. Incorporation of 2'-O,4'-C-ethylene nucleosides into oligonucleotides dramatically increase their resistance against exonucleases. In this review, the properties of ENA oligonucleotides and some of their applications as antisense and antigene oligonucleotides are described.

Bridged-Ring Compounds↗
PubMed2003

Triplex formation with 2'-O,4'-C-ethylene-bridged nucleic acids (ENA) having C3'-endo conformation at physiological pH.

Antigenes, which are substances that inhibit gene expression by binding to double-stranded DNA (dsDNA) in a sequence-specific manner, are currently sought for the treatment of various gene-related diseases. As such antigenes, we developed new nuclease-resistant oligopyrimidine nucleotides that are partially modified with 2'-O,4'-C-ethylene nucleic acids (ENA), which are constrained in the C3'-endo conformation and can form a triplex with dsDNA at physiological pH. It was found that these oligonucleotides formed triplexes similarly to those partially modified with 2'-O,4'-C-methylene nucleic acids (2',4'-BNA or LNA), as determined by UV melting analyses, electromobility shift assays, CD spectral analyses and restriction enzyme inhibition assays. In our studies, oligonucleotides fully modified with ENA have delta torsion angle values that are marginally higher than those of 2',4'-BNA/LNA. ENA oligonucleotides present in 10-fold the amount of dsDNA were found to be favorable in forming triplexes. These results provide useful information for the future design of triplex-forming oligonucleotides fully modified with such nucleic acids constrained in the C3'-endo conformation considering that oligonucleotides fully modified with 2',4'-BNA/LNA do not form triplexes.

Base Sequence↗
PubMed2003

Synthesis and properties of 2'-O,4'-C-ethylene-bridged nucleic acids (ENA) as effective antisense oligonucleotides.

Novel bicyclo nucleosides, 2'-O,4'-C-ethylene nucleosides and 2'-O,4'-C-propylene nucleosides, were synthesized as building blocks for antisense oligonucleotides to further optimize the 2'-O,4'-C-methylene-linkage of bridged nucleic acids (2',4'-BNA) or locked nucleic acids (LNA). Both the 2'-O,4'-C-ethylene- and propylene-linkage within these nucleosides restrict the sugar puckering to the N-conformation of RNA as do 2',4'-BNA/LNA. Furthermore, ethylene-bridged nucleic acids (ENA) having 2'-O,4'-C-ethylene nucleosides had considerably increased the affinity to complementary RNA, and were as high as that of 2',4'-BNA/LNA (DeltaT(m)=+3 approximately 5 degrees C per modification). On the other hand, addition of 2'-O,4'-C-propylene modifications in oligonucleotides led to a decrease in the affinity to complementary RNA. As for the stability against nucleases, incorporation of one 2'-O,4'-C-ethylene or one 2'-O,4'-C-propylene nucleoside into oligonucleotides considerably increased their resistance against exonucleases to an extent greater than 2',4'-BNA/LNA. These results indicate that ENA is more suitable as an antisense oligonucleotide and is expected to have better antisense activity than 2',4'-BNA/LNA.

Alkenes↗
PubMed2003

Design and synthesis of oatp subtype-specific antisense oligonucleotides having 2'-O,4'-C-ethylene-bridged nucleic acids (ENA).

To select antisense oligonucleotides (AONs) that specifically target the genes of rat organic anion transporting polypeptide (oatp) subtypes, in vitro selection and an alignment program were used. When we incorporated a couple of our original 2'-O,4'-C-ethylene nucleoside (ENA) residues into the AONs at both the 3' and 5' ends, the inhibitory activity of these oatp subtype-specific AONs was enhanced. This strategy of combining in vitro selection with the use of an alignment program as well as incorporating ENA residues, was effective in synthesizing oatp subtype-specific AONs.

Base Sequence↗
PubMed2002

2'-O,4'-C-ethylene-bridged nucleic acids (ENA): highly nuclease-resistant and thermodynamically stable oligonucleotides for antisense drug.

To develop antisense oligonucleotides, novel nucleosides, 2'-O,4'-C-ethylene nucleosides and their corresponding phosphoramidites, were synthesized as building blocks. The 1H NMR analysis showed that the 2'-O,4'-C-ethylene linkage of these nucleosides restricts the sugar puckering to the N-conformation as well as the linkage of 2'-O,4'-C-methylene nucleosides which are known as bridged nucleic acids (BNA) or locked nucleic acids (LNA). The ethylene-bridged nucleic acids (ENA) showed a high binding affinity for the complementary RNA strand (DeltaT(m)=+5.2 degrees C/modification) and were more nuclease-resistant than natural DNA and BNA/LNA. These results indicate that ENA have better properties as antisense oligonucleotides than BNA/LNA.

Bridged-Ring Compounds↗