***** seminarMLから情報転載 *****


日時 : 平成21年 11月 13日 (金曜日) 16:00 ~ 17:00

会場 : (財)東京都医学研究機構 東京都臨床医学総
合研究所 2階講堂

演題 : Replication speed and mitotic remodeling of chromatin
loops&s_comma; but not histone acetylation&s_comma; control origin usage in mammalian
cells (動物細胞における複製起点選択の制御機構:複

演者 : Michelle Debatisse 教授 (Institut Curie&s_comma; フランス)


Mammalian cells have many more potential replication origins than they
activate in each S phase&s_comma; some origins being more efficient than
others. We have used molecular combing to study the replication
dynamics along the AMPD2 domain in Chinese hamster cells. We have
found that oriGNAI3&s_comma; which is nested within a large matrix attachment
region&s_comma; is the most efficient replication origin of this domain when
cells are grown under conditions allowing fast progression of
replication forks. However&s_comma; slowing down replication speed triggers
the recruitment of otherwise silent origins. We have shown that this
compensatory process occurs almost instantaneously in response to
speed variations. Surprisingly&s_comma; when shifted to a growth medium
supporting a high replication speed&s_comma; even though the number of active
origins decreases immediately&s_comma; the cells have to go through a complete
cell cycle before the hierarchy of origins&s_comma; ie the prominence of
oriGNAI3&s_comma; is restored. Interestingly&s_comma; we have observed a strict
correlation between replication speed during a given S phase and the
size of chromatin loops in the next G1 phase. These data suggest a new
level of origin programming&s_comma; in which the replication speed determines
the spacing of sequences attached to the nuclear matrix and&s_comma; in turn&s_comma;
controls the choice of initiation sites. Origin hierarchy would thus
reflect their relative affinity for the nuclear matrix.

Replication fork movement sets chromatin loop size and origin choice
in mammalian cells.&s_comma; Courbet S&s_comma; Gay S&s_comma; Arnoult N&s_comma; Wronka G&s_comma;
Anglana M&s_comma; Brison O&s_comma; Debatisse M.&s_comma; Nature. 2008 Sep 25;455(7212):
557-60. など

〔世話人:ゲノム動態プロジェクト 正井 久雄〕

Hisao Masai
Genome Dynamics Project&s_comma;
Tokyo Metropolitan Institute of Medical Science&s_comma;
2-1-6 Kamikitazawa&s_comma; Setagaya-ku&s_comma; Tokyo 156-8506&s_comma; JAPAN
Tel: 81-3-5316-3231 Fax: 81-3-5316-3145; E-mail: masai-hs@igakuken.or.jp

正井 久雄
東京都臨床医学総合研究所 ゲノム動態プロジェクト
郵便番号 156-8506
所在地  東京都世田谷区上北沢二丁目1番6号
正井直通電話 03-5316-3231
研究室電話 03-5316-3117
研究室FAX 03-5316-3145
E-mail masai-hs@igakuken.or.jp