Regulation of DNA replication timing on human chromosome by a cell-type specific DNA binding protein SATB1.

Genome Dynamics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
PLoS ONE (Impact Factor: 3.53). 01/2012; 7(8):e42375. DOI: 10.1371/journal.pone.0042375
Source: PubMed

ABSTRACT Replication timing of metazoan DNA during S-phase may be determined by many factors including chromosome structures, nuclear positioning, patterns of histone modifications, and transcriptional activity. It may be determined by Mb-domain structures, termed as "replication domains", and recent findings indicate that replication timing is under developmental and cell type-specific regulation.
We examined replication timing on the human 5q23/31 3.5-Mb segment in T cells and non-T cells. We used two independent methods to determine replication timing. One is quantification of nascent replicating DNA in cell cycle-fractionated stage-specific S phase populations. The other is FISH analyses of replication foci. Although the locations of early- and late-replicating domains were common between the two cell lines, the timing transition region (TTR) between early and late domains were offset by 200-kb. We show that Special AT-rich sequence Binding protein 1 (SATB1), specifically expressed in T-cells, binds to the early domain immediately adjacent to TTR and delays the replication timing of the TTR. Measurement of the chromosome copy number along the TTR during synchronized S phase suggests that the fork movement may be slowed down by SATB1.
Our results reveal a novel role of SATB1 in cell type-specific regulation of replication timing along the chromosome.

  • [Show abstract] [Hide abstract]
    ABSTRACT: In the genome of eukaryotic cells, DNA synthesis is initiated at multiple sites called origins of DNA replication. Origins must fire only once per cell cycle and how this is achieved is now well understood. However, little is known about the mechanisms that determine when and where replication initiates in a given cell. A large body of evidence indicates that origins are not equal in terms of efficiency and timing of activation. Origin usage also changes concomitantly with the different cell differentiation programs. As DNA replication occurs in the context of chromatin, initiation could be influenced by multiple parameters, such as nucleosome positioning, histone modifications, and three-dimensional (3D) organization of the nucleus. This view is supported by recent genome-wide studies showing that DNA replication profiles are shaped by genetic and epigenetic processes that act both at the local and global levels to regulate origin function in eukaryotic cells.
    Current opinion in genetics & development 03/2013; · 8.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Origins of DNA replication on eukaryotic genomes have been observed to fire during S phase in a coordinated manner. Studies in yeast indicate that origin firing is affected by several factors, including checkpoint regulators and chromatin modifiers. However, it is unclear what the mechanisms orchestrating this coordinated process are. Recent studies have identified factors that regulate the timing of origin activation, including Rif1 which plays crucial roles in the regulation of the replication timing program in yeast as well as in higher eukaryotes. In mammalian cells, Rif1 appears to regulate the structures of replication timing domains through its ability to organize chromatin loop structures. Regulation of chromatin architecture by Rif1 may be linked to other chromosome transactions including recombination, repair, or transcription. This review summarizes recent progress in the effort to elucidate the regulatory mechanisms of replication timing of eukaryotic replicons.
    Trends in Genetics 06/2013; · 9.77 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The morphology of fertilization events has been related to successful implantation by subjective criteria (pronuclei score, pronuclei symmetry and position). This work first described these events by time-lapse technology and then compared the timings of fertilization events (second polar body extrusion, first and second pronuclei appearance, abuttal and fading) in implanted versus nonimplanted embryos in a 2-year cohort retrospective study. A total of 1448 transferred embryos from 842 patients undergoing intracytoplasmic sperm injection with oocyte donation were monitored, 212 embryos from treatments where the number of gestational sacs matched the number of transferred embryos and 687 embryos from treatments no biochemical pregnancy was achieved. The timings at which second polar body extrusion (3.3–10.6 h), pronuclear fading (22.2–25.9 h) and length of S-phase (5.7–13.8 h) occurred were linked successfully to embryo implantation. The other parameters were apparently not related, as determined by image acquisition and time-lapse analysis.
    Reproductive biomedicine online 01/2014; 28:475-484. · 2.68 Impact Factor

Full-text (2 Sources)

Available from