Kazumitsu Onizuka

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The formation of interstrand cross-links in nucleic acids can have a strong impact on biological function of nucleic acids; therefore, many cross-linking agents have been developed for biological applications. Despite numerous studies, there remains a need for cross-linking agents that exhibit both efficiency and selectivity. In this study, a(More)
Short interfering RNA (siRNA)-triggered gene knockdown through the RNA interference (RNAi) pathway is widely used to study gene function, and siRNA-based therapeutics are in development. However, as the guide strand of an siRNA can function like a natural microRNA (miRNA), siRNAs often repress hundreds of off-target transcripts with complementarity only to(More)
Modified nucleosides in natural RNA molecules are essential for their functions. Non-natural nucleoside analogues have been introduced into RNA to manipulate its structure and function. We have recently developed a new strategy for the in situ modification of RNA based on the functionality transfer reaction between an oligodeoxynucleotide probe and an RNA(More)
Short interfering RNAs (siRNAs) are promising therapeutics that make use of the RNA interference (RNAi) pathway, but liabilities arising from the native RNA structure necessitate chemical modification for drug development. Advances in the structural characterization of components of the human RNAi pathway have enabled structure-guided optimization of siRNA(More)
A variety of enzymes have been found to interact with double-stranded RNA (dsRNA) in order to carry out its functions. We have endeavored to prepare the covalently crosslinked native-like duplex RNA, which could be useful for biochemical studies and RNA nanotechnology. In this study, the interstrand covalently linked duplex RNA was formed by a crosslinking(More)
Efficient methods for the modification of RNA molecules have been expected as innovative biological tools and therapeutic methods. In this study, the development of a general method for site-specific RNA modification by the functionality-transfer ODN probes has been investigated. Site-specific and cytosine-selective RNA modifications were achieved by the(More)
Site-specific modification of nucleic acid is of great significance in the machinery of gene expression. Specific modification of nucleic acids by an oligonucleotide incorporating a S-vinyl thioguanosine analog, has great potential as a useful tool. The specific transfer of the vinyl derivative to the amino group of dC at the target site of the(More)
O(6)-Methyl-2'-deoxyguanosine (O(6)-Me-dG) is a mutagenic nucleotide in DNA. O(6)-Me-dG in DNA was rapidly and selectively modified by a functionality transfer reaction using the ODN incorporating 6-S-functionalized thioguanosine. Subsequent labelling of O(6)-Me-dG with the fluorescent FAM or biotin group via click chemistry has permitted the sensitive and(More)
Thymine glycol (Tg), one of the oxidized bases formed in DNA by reactive oxygen species, is repaired by the DNA glycosylases such as NEIL1, NTH1 and Endo III. In our recent studies, we showed that NEIL1's catalytic efficiency and lesion specificity are regulated by an RNA-editing adenosine deamination reaction. In this study, we synthesized(More)
Chemically modified oligonucleotides play a significant role for genomic research. Modified nucleosides, such as with a fluorescent dye, can be obtained by chemical synthesis. Site-specifically modified long nucleic acids are obtained by ligation of chemically modified short oligonucleotides with enzyme, photochemistry, or catalytic DNA. The(More)