Duplication and maintenance of heterochromatin domains

Citation
A. Taddei et al., Duplication and maintenance of heterochromatin domains, J CELL BIOL, 147(6), 1999, pp. 1153-1166
Citations number
82
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
JOURNAL OF CELL BIOLOGY
ISSN journal
0021-9525 → ACNP
Volume
147
Issue
6
Year of publication
1999
Pages
1153 - 1166
Database
ISI
SICI code
0021-9525(199912)147:6<1153:DAMOHD>2.0.ZU;2-E
Abstract
To investigate the mechanisms that assure the maintenance of heterochromati n regions, we took advantage of the fact that clusters of heterochromatin D NA replicate late in S phase and are processed in discrete foci with a char acteristic nuclear distribution. At the light microscopy level, within thes e entities, we followed DNA synthesis, histone H4 acetylation, heterochroma tin protein 1 (Hp1 alpha and -beta), and chromatin assembly factor 1 (CAF-1 ). During replication, Hp1 alpha and -beta domains of concentration are sta bly maintained, whereas heterochromatin regions are enriched in both CAF-1 and replication-specific acetylated isoforms of histone H4 (H4Ac 5 and 12). We defined a time window of 20 min for the maintenance of this state. Furt hermore, treatment with Trichostatin A (TSA), during and after replication, sustains the H4Ac 5 and 12 state in heterochromatin excluding H4Ac 8 and 1 6. In comparison, early replication foci, at the same level, did not displa y any specific enrichment in H4Ac 5 and 12. These data emphasize the specif ic importance for heterochromatin of the replication-associated H4 isoforms . We propose that perpetuation of heterochromatin involves self-maintenance factors, including local concentration of Hp1 alpha and -beta, and that a degree of plasticity is provided by the cycle of H4 acetylation/deacetylati on assisted by CAF-1.