Chandok GS, Kapoor KK, Brick RM, Sidorova JM, Krasilnikova MM. A distinct first replication cycle of DNA introduced in mammalian cells.
Nucleic Acids Res 2011;
39:2103-15. [PMID:
21062817 PMCID:
PMC3064806 DOI:
10.1093/nar/gkq903]
[Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 08/30/2010] [Accepted: 09/23/2010] [Indexed: 11/24/2022] Open
Abstract
Many mutation events in microsatellite DNA sequences were traced to the first embryonic divisions. It was not known what makes the first replication cycles of embryonic DNA different from subsequent replication cycles. Here we demonstrate that an unusual replication mode is involved in the first cycle of replication of DNA introduced in mammalian cells. This alternative replication starts at random positions, and occurs before the chromatin is fully assembled. It is detected in various cell lines and primary cells. The presence of single-stranded regions increases the efficiency of this alternative replication mode. The alternative replication cannot progress through the A/T-rich FRA16B fragile site, while the regular replication mode is not affected by it. A/T-rich microsatellites are associated with the majority of chromosomal breakpoints in cancer. We suggest that the alternative replication mode may be initiated at the regions with immature chromatin structure in embryonic and cancer cells resulting in increased genomic instability. This work demonstrates, for the first time, differences in the replication progression during the first and subsequent replication cycles in mammalian cells.
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