ProfessorUniversity of Hiroshima
Director of Amphibian Research Center at Hiroshima University Head of the Division of Bioresource Science Topics of Research Recent progress in comparative genomics has revealed significant conservation of the coding sequences of developmental genes in animal kingdom. Hence it is now believed that changes in the remaining part of the genes, i.e., cis-regulatory sequences controlling their spatio-temporal expression, played a major role in the evolution of animal diversity. Especially in vertebrate evolution, two rounds of whole genome duplications that occurred in the Cambrian ancestors likely accelerated the cis-regulatory evolution by generating a number of duplicated gene pairs (known as paralogs) from the ancestral gene set, and led the later species explosion. We are studying such cis-regulatory changes for molecular understanding of morphological evolution. In addition, we are studying mechanisms that underlie species differences of tissue regenerating ability from the view of cis-regulatory and epigenetic evolution. (1) Differences between amphioxus and human—the genome duplication and cis-regulatory evolution Since the "living fossil" amphioxus phylogenetically diverged from the vertebrate lineage before the genome duplications occurred, it likely retains ancestral-modes of gene regulation. Using in silico approach (comparative genome sequence analysis) and in vivo approach (high-throughput transgenic reporter assay in Xenopus), we are investigating functional differences in the cis-regulation of amphioxus and vertebrates to reveal the evolution of developmental gene regulatory network. Recently we revealed that silencer innovation, rather than enhancer degeneration, was crucial for the diversification of paralog expression after the genome duplications (Nature communications, 2012). (2) Epigenetic regulation in tissue regeneration Epigenetic modifications, such as DNA methylation, and histone methylation and acetylation, determine chromatin conformation states and regulate stem cell maintenance and differentiation. We are investigating the roles for such epigenetic modifications in the regeneration of eye and central nervous tissues in amphibians. The goal of this research is to confer the amphibian-like, strong regeneration ability to injured part of mammalian bodies by manipulating the epigenetic modifications. Selected publications 1. Ochi, H., Tamai, T., Nagano, H., Kawaguchi, A., Sudou, N. and Ogino, H. Evolution of a tissue-specific silencer underlies divergence in the expression of pax2 and pax8 paralogues. Nature Communications 3: 848 (2012). 2. Kawaguchi, A., Ochi, H., Sudou, N. and Ogino, H. Comparative expression analysis of the H3K27 demethylases, JMJD3 and UTX, with the H3K27 methylase, EZH2, in Xenopus. Int. J. Dev. Biol. 56: 295-300 (2012). 3. Ogino, H., Fisher, M. and Grainger, R. M. Convergence of a head-field selector Otx2 and Notch signaling: a mechanism for lens specification. Development135: 249-258 (2008). 4. Ogino, H., McConnell, W. B. and Grainger, R. M. High-throughput transgenesis in Xenopus using I-SceI meganuclease. Nature Protocol 1: 1703-1710 (2006) 5. Ogino, H. and Yasuda, K. Induction of lens differentiation by activation of a bZIP transcription factor, L-Maf. Science 280:115-118 (1998).
Organization MembershipsNational BioResource Project (NBRP) (Faculty)