BOVINE SATELLITE DNA INDUCES HETEROCHROMATINIZATION OF HOST
CHROMOSOMAL DNA IN CELLS OF TRASSATELLITE MOUSE EMBRYONAL CARCINOMA
I. O. Suchkova,1 T. V. Baranova,1 M. E. Kustova,1
T. V. Kisljakova,2 V. B. Vassiliev,1 N. O. Slominskaja,1
N. V. Alenina,2, 3 E. L. Patkin1 *
1 Institute of Experimental Medicine RAMS, St. Petersburg, 2
Institute of Cytology RAS, St. Petersburg, and 3 Max Delbruck Center for Molecular Medicine, Berlin, Germany;
* e-mail: Patkin@EP4686.spb.edu
Embryonal teratocarcinoma F9 cells were transfected with a fragment (3.8 kb) of bovine satellite DNA IV (Sat),
which is not homologous to mouse satellite DNA. FISH analysis revealed various chromosomal integration sites of
integrated Sat in different transsatellite clones. After several passages, transsatellite had a tendency to spread
along chromosome bearing Sat in one of the studied lines. The integrated transsatellites were enriched with prolonged
single-strand DNA regions (SSR) revealed by FISH without previous chromosomal denaturati-on, and were unmethylated.
The observed SSR are presumably supposed to represent intermediates of transsatellite DNA instability via unequal
sister chromatid exchanges. DAPI staining demonstrated that the integrated Sat induced the formation of prominent
ectopic neoheterochromatin blocks in regions adjacent to integrated Sat. These blocks were located exclusively
between integrated Sat and centromeric heterochromatin. Thus, mouse repetitive centromeric DNA (AT-rich,
DAPI-positive) "spreads" along the chromosome in response to integration of the bovine satellite GC-rich DNA.
The results obtained are discussed in the context of possible position effect variegation mechanisms operating in
undifferentiated cells.
Key words: heterochromatin formation, satellite DNA instability, transsatellite cells, embryonal
teratocarcinoma, single-strand DNA regions, FISH
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