Abstract
Higher eukaryotes cell nucleus has a compartmentalized structure built up by
chromosome territories (CTs) and an interchromatin compartment (IC). The IC
expands both between neighboring CTs and into the interior of indivisual CT
s and is lined by the surfaces of smaller and larger chromatin domains. Howe
ver, little is known about the dynamic organization of higher order nuclear
architectures including chromatin and non-chromatin nuclear domains after in
duction of DNA damage. To examine the dynamic organization of higher order
nuclear architecture for DNA repair, we have developed a system for local ir
radiation of cell nuclei using a focused UV-laser (laser-UV-microirradiation
). Using this techniques, we have revealed that DNA repair related proteins,
such as gamma H2AX, MRE11, RAD51 and PML, accumulated at site of containing
DNA damage at various times after induction of DNA damage. To examine the t
opological and chronological relationships between these non-chromatin nucle
ar domains associated with DNA repair in a single cell, we have developed a
multicolor immunofluorescence staining system. Using this method, we have re
vealed that the dynamics of 53BP1, a protein involved in the signaling of DN
A damage, was differently regulated after low and high dose gamma irradiatio
n, respectively. Dynamic organization of higher order nuclear architecture f
or DNA repair will be discussed.
