Devising new electron microscopy approach to explore the morphology of chromatin in cell nucleus

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K19301
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 43:Biology at molecular to cellular levels, and related fields
• Research Institution: Hiroshima University
• Principal Investigator: Tate Shin-ichi 広島大学, 統合生命科学研究科(理), 教授 (20216998)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: FIB-SEM / クロマチン構造 / 分裂酵母 / 電子顕微鏡

Outline of Final Research Achievements

We have successfully observed the three-dimensional (3D) electron microscopic image of chromatin in cell-nucleus with focused ion-beam scanning electron microscopy (FIB-SEM). This gives the first example for describing the whole chromatin 3D structure within cell-nucleus at a single-cell level.
We have established the 3D structure analysis of the whole chromatin within cell nucleus. The fission yeast cells that harbor histone H2B-APEX2 fusion protein enabled the diaminobenzidine (DAB) coating around the chromatin fibers inside the cell nucleus, thus allowed the osmium-ion staining to give high contrast EM image of the chromatin within the cell nucleus. The numerical processing software devised in this research achieved very efficient reconstruction of the 3D EM image of chromatins from a series of SEM images from FIB-SEM. This EM technology will pave ways in the study of gene regulation from the whole chromatin 3D structural points of view.

Free Research Field

構造生物学

Academic Significance and Societal Importance of the Research Achievements

細胞の遺伝情報制御機構の解明は，ガンなど疾病発症機構や細胞の分化制御機構の理解につながる細胞生物学の中心的なテーマである．分子生物学は，DNAとタンパク質の局所的な相互作用を明らかにしてきた．一方で，最近の研究は，核内で遺伝情報を保持する「クロマチン」構造が，局所の分子間相互作用を調節する機構の存在を示唆している．しかし，核内クロマチン全体の立体構造を観測する技術が無いため研究されていない．私達は核内クロマチンの3次元構造を明らかにする電子顕微鏡技術を構築した．この技術により，クロマチン全体の構造変化による遺伝情報制御機構を解明する新たな細胞生物学研究が可能になる．