Ohtsuki's group


Our major concerns are to develop RNA technologies and peptide technologies, and to expand protein biosynthesizing system to incorporate non-natural amino acids.

Keywords: tRNA, siRNA, shRNA, noncoding RNA, RNAi, RNA delivery, RNA purification, RNA detection, protein biosynthesis, translation, non-natural amino acid, peptide library, peptide nucleic acid.

1) Development of methods for RNA delivery and peptide delivery.

Methods that facilitate the cellular internalization of RNAs and peptides are widely utilized in medical and biological studies.  We developed methods for the intracellular delivery of small RNAs using carrier peptides, primarily cationic cell-penetrating peptides (CPPs) and carrier proteins (Bioconjug Chem, 2011 [doi]; Bioorg.Med.Chem.Lett. 2009 [doi]). Especially, we are interested in the photo-dependent cytosolic RNA delivery strategy based on a photochemical internalization mechanism (Sci. Rep. 2015  [doi]). In addition to the photo-dependent RNA delivery, we recently reported photo-dependent delivery of apoptosis inducing peptides (Bioorg. Med.Chem. Lett. 2016 [doi]).


2) CLIP-RNAi technology (Spatial regulation of RNA interference by light).

We devised a method for photoinduced RNA interference (RNAi) (J.Control.Release, 2009 [doi]). This photoinduced RNAi strategy was termed CLIP-RNAi (CPP-Linked RBP-Mediated RNA Internalization and Photoinduced RNAi). This method enables spatiotemporal control of gene expression by light. Recently, we expanded the excitation wavelength of the CLIP-RNAi method to the near-infrared region (Bioconjug. Chem. 2013 [doi]).

3) Expansion of protein biosynthesis system, and its application.

Nonnatural amino acids can be incorporated into proteins by delivery of an aminoacylated suppressor tRNA to a ribosome associated with mRNA containing an expanded codon/anticodon pair. This methodology provides a powerful tool for analyzing protein structure and function, and for producing proteins with new properties. We devised artificial tRNAs and EF-Tu mutants for efficient incorporation of nonnatural amino acids (J. Am. Chem. Soc. 2007 [doi]; FEBS lett. 2005 [doi]). We are considering applications of this expanded protein biosynthesis system (Bioorg. Med. Chem. Lett.2014 [doi]; Anal. Biochem. 2011 [doi]; Biochem. Biophys. Res. Commun. 2011 [doi]; Anal. Biochem. 2009 [doi]).

4) Development of the methods for RNA isolation and RNA detection using artificial nucleic acids.

We developed PNA-based methods for RNA isolation (J. Biochem. 2008 [doi]) and RNA detection (Chem.Lett. 2009 [doi]), and we are considering new methods for RNA detection and RNA analysis in living cells using new artificial nucleic acids (e.g. Tetrahedron, 2010 [doi]).


Principal Investigator  Takashi Ohtsuki
Department of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan.
Email:  ohtsuk (at) okayama-u.ac.jp

  Takashi OHTSUKI, PhD, Professor

    Kazunori Watanabe, PhD, Assistant Professor


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