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Biological Macromolecules Laboratory • Maeshima Group

3D-organization and dynamics of human genome chromatin

Professor MAESHIMA, Kazuhiro kmaeshim
Assistant Professor HITRATANI, Ichiro ihiratan

Homepage URL : http://www.nig.ac.jp/labs/MacroMol/index.html

Our research interest lies in determining how a long string of genomic DNA is
three-dimensionally organized in mitotic chromosomes and the nucleus, and
how the organized genome functions during cellular proliferation, differentiation,
and development. We are using a novel combination of molecular cell
biology and biophysics to elucidate 3D-organization and dynamics of human
genome chromatin. Current on-going projects are as follows:

• Analysis of chromatin dynamics in nuclei and mitotic chromosomes by quantitative live-cell imaging
• Structural study of nuclei and mitotic chromosomes by X-ray scattering and cryo-electron microscopy
• Genome-wide study of higher-order chromatin change(s) during ES cell differentiation
• Understanding of nuclear assembly and growth mechanisms during cellcycle

In our structural study by cryo-EM, we did not find any higher-order structures in mitotic chromosomes, or even 30-nm chromatin fibers (A), but just a uniform disordered texture (B). We thus propose that mitotic chromosomes consist of 11-nm nucleosome fibers folded irregularly.

Maeshima, K., Iino, H., Hihara, S., Funakoshi, T., Watanabe, A., Nishimura, M., Nakatomi, R., Yahata, K., Imamoto, F., Hashikawa, T., et al. (2010). Nuclear pore formation but not nuclear growth is governed by cyclin-dependent kinases (Cdks) during interphase. Nat Struct Mol Biol 17, 1065-1071.

Maeshima, K., Hihara, S., and Eltsov, M. (2010). Chromatin structure: does the 30-nm fibre exist in vivo? Curr Opin Cell Biol 22, 291-297.

Hiratani, I., Ryba, T., Itoh, M., Rathjen, J., Kulik, M., Papp, B., Fussner, E., Bazett-Jones, D.P., Plath, K., Dalton, S., et al. (2010). Genome-wide dynamics of replication timing revealed by in vitro models of mouse embryogenesis. Genome Res 20, 155-169.

Takemoto, A., Maeshima, K., Ikehara, T., Yamaguchi, K., Murayama, A., Imamura, S., Imamoto, N., Yokoyama, S., Hirano, T., Watanabe, Y., et al. (2009). The chromosomal association of condensin II is regulated by a noncatalytic function of PP2A. Nat Struct Mol Biol 16, 1302-1308.

Nishino, Y., Takahashi, Y., Imamoto, N., Ishikawa, T., and Maeshima, K. (2009). Three-dimensional visualization of a human chromosome using coherent X-ray diffraction. Phys Rev Lett 102, 018101.

Eltsov, M., Maclellan, K.M., Maeshima, K., Frangakis, A.S., and Dubochet, J. (2008). Analysis of cryo-electron microscopy images does not support the existence of 30-nm chromatin fibers in mitotic chromosomes in situ. Proc Natl Acad Sci U S A 105, 19732-19737.


Professor MAESHIMA, Kazuhiro kmaeshim	Assistant Professor HIRATANI, Ichiro 　 ihiratan

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