The replication timing program of the Chinese hamster beta-globin locus isestablished coincident with its repositioning near peripheral heterochromatin in early G1 phase

Citation
F. Li et al., The replication timing program of the Chinese hamster beta-globin locus isestablished coincident with its repositioning near peripheral heterochromatin in early G1 phase, J CELL BIOL, 154(2), 2001, pp. 283-292
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
JOURNAL OF CELL BIOLOGY
ISSN journal
0021-9525 → ACNP
Volume
154
Issue
2
Year of publication
2001
Pages
283 - 292
Database
ISI
SICI code
0021-9525(20010723)154:2<283:TRTPOT>2.0.ZU;2-R
Abstract
We have examined the dynamics of nuclear repositioning and the establishmen t of a replication timing program for the actively transcribed dihydrofolat e reductase (DHFR) locus and the silent beta -globin gene locus in Chinese hamster ovary cells. The DHFR locus was internally localized and replicated early, whereas the beta -globin locus was localized adjacent to the nuclea r periphery and replicated during the middle of S phase, coincident with re plication of peripheral heterochromatin. Nuclei were prepared from cells sy nchronized at various times during early G1 phase and stimulated to enter S phase by introduction into Xenopus egg extracts, and the timing of DHFR an d beta -globin replication was evaluated in vitro. With nuclei isolated 1 h after mitosis, neither locus was preferentially replicated before the othe r. However, with nuclei isolated 2 or 3 h after mitosis, there was a strong preference for replication of DHFR before beta -globin. Measurements of th e distance of DHFR and beta -globin to the nuclear periphery revealed that the repositioning of the beta -globin locus adjacent to peripheral heteroch romatin also took place between 1 and 2 h after mitosis. These results sugg est that the CHO beta -globin locus acquires the replication timing program of peripheral heterochromatin upon association with the peripheral subnucl ear compartment during early G1 phase.