Dynamic alterations of replication timing in mammalian cells

Chii Mei Lin, Haiqing Fu, Maria Martinovsky, Eric E. Bouhassira, Mirit I. Aladjem

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Background: The eukaryotic genome is divided into distinct replication timing domains, which are activated during S phase in a strictly conserved order. Cellular differentiation can alter replication timing in some loci, but recent experiments yielded conflicting data regarding the relationship between gene expression and replication timing. The genetic and epigenetic determinants of replication timing in mammalian cells have yet to be elucidated. Results: We developed a mammalian experimental system in which the timing of DNA replication can be altered in a controlled manner. This system utilizes sequences from the human β-globin locus that exhibit orientation-dependent transcriptional silencing when inserted into the murine genome. We found that before insertion, the murine target site replicated late during S phase. After insertion, replication timing depended on the orientation of the transgene. In a transcription-permissive orientation, the transgene and flanking sequences replicated early. In the reverse (silencing-prone) orientation, these sequences replicated late. Early replication correlated with histone modifications of the transgene chromatin but could be observed in the absence of the β-globin promoter. Importantly, the replication timing switch did not require a replication origin within the transgene. Conclusions: Transgene insertions into mammalian heterochromatin can alter the timing of DNA replication at the insertion site. This differentiation-independent replication timing switch did not necessitate insertion of an active promoter or a replication origin. These observations suggest that the timing of DNA replication can be manipulated by changes in DNA sequence, but that the determinants of replication timing are distinct from the sequences that specify replication initiation sites.

Original languageEnglish (US)
Pages (from-to)1019-1028
Number of pages10
JournalCurrent Biology
Volume13
Issue number12
DOIs
StatePublished - Jun 17 2003

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DNA Replication Timing
Transgenes
transgenes
Replication Origin
Globins
Cells
DNA replication
DNA
replication origin
Genes
Switches
S Phase
interphase
DNA sequences
cells
Transcription
Gene expression
Histone Code
Histones
Chromatin

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)

Cite this

Dynamic alterations of replication timing in mammalian cells. / Lin, Chii Mei; Fu, Haiqing; Martinovsky, Maria; Bouhassira, Eric E.; Aladjem, Mirit I.

In: Current Biology, Vol. 13, No. 12, 17.06.2003, p. 1019-1028.

Research output: Contribution to journalArticle

Lin, Chii Mei ; Fu, Haiqing ; Martinovsky, Maria ; Bouhassira, Eric E. ; Aladjem, Mirit I. / Dynamic alterations of replication timing in mammalian cells. In: Current Biology. 2003 ; Vol. 13, No. 12. pp. 1019-1028.
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