THE ROLE OF DNA METHYLATION AND HISTONE MODIFICATIONS IN STRUCTURAL MAINNTAINANCE OF HETEROCHROMATIN DOMAINS
(CHROMOCENTERS)
S. A. Golyshhev,1 P. N. Vichreva, E. V. Sheval, G. I. Kiryanov, V. Yu. Polyakov
A. N. Belozerski Institute of Physico-Ñhemical Biology, Moscow State University;
1 e-mail: sergei.golyshev@mail.genebee.msu.ru
The effects of DNA methylation inhibitor 5-azacytidine (5-aza-C) and histone acetylation inhibitor trichos-tatine A (TSA) on the structure of pericentric
heterochromatin in cultured mouse cells (L929) has been studied. After 48 h of 5-aza-C treatment, about 85 % of the cells demonstrate transformation of
chromocenters from ovoid to elongated structures. Hypotonic treatment of these cells reveals tandemly arranged DAPI-positive globules, well distinguishable by
light microscopy. The same globular units can be revealed in hypotonic-treated control cells. 48 h of TSA treatment causes dramatic decrease in HP1á content in
the cells. Chromocenters in 25 % of treated cells became highly decondenced and can not be reliably detected by light and electron microscopy. 85 % of cells
demonstrate globular chromocenters with low HP1á content. Hypotonic treatment causes transformation of compact chromocenters into ring-like structures, which
can be either single or clustered. Rings are formed by uniform fiber, in which no globular subunits are detected. The data obtained are discussed concerning several
mechanisms of heterochromatin structure maintenance and the roles of epigenetic marks in them.
Key words: heterochromatin, chromocenter, DNA methylation, histone methylation, histone acetylation, chromatin structure, inhibition analysis
Back
Contents
Main
