A reduction of licensed origins reveals strain-specific replication dynamics in mice

A reduction of licensed origins reveals strain-specific replication dynamics in mice Replication origin licensing builds a fundamental basis for DNA replication in all eukaryotes. This occurs during the late M to early G1 phases in which chromatin is licensed by loading of the MCM2-7 complex, an essential component of the replicative helicase. In the following S phase, only a minor fraction of chromatin-bound MCM2-7 complexes are activated to unwind the DNA. Therefore, it is proposed that the vast majority of MCM2-7 complexes license dormant origins that can be used as backups. Consistent with this idea, it has been repeatedly demonstrated that a reduction (~60%) in chromatin-bound MCM2-7 complexes has little effect on the density of active origins. In this study, however, we describe the first exception to this observation. A reduction of licensed origins due to Mcm4 chaos3 homozygosity reduces active origin density in primary embryonic fibroblasts (MEFs) in a C57BL/6J (B6) background. We found that this is associated with an intrinsically lower level of active origins in this background compared to others. B6 Mcm4 chaos3/chaos3 cells proliferate slowly due to p53-dependent upregulation of p21. In fact, the development of B6 Mcm4 chaos3/chaos3 mice is impaired and a significant fraction of them die at birth. While inactivation of p53 restores proliferation in B6 Mcm4 chaos3/chaos3 MEFs, it paradoxically does not rescue animal lethality. These findings indicate that a reduction of licensed origins may cause a more profound effect on cell types with lower densities of active origins. Moreover, p53 is required for the development of mice that suffer from intrinsic replication stress. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Mammalian Genome Springer Journals

A reduction of licensed origins reveals strain-specific replication dynamics in mice

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Publisher
Springer-Verlag
Copyright
Copyright © 2011 by Springer Science+Business Media, LLC
Subject
Life Sciences; Anatomy; Cell Biology; Zoology
ISSN
0938-8990
eISSN
1432-1777
D.O.I.
10.1007/s00335-011-9333-7
Publisher site
See Article on Publisher Site

Abstract

Replication origin licensing builds a fundamental basis for DNA replication in all eukaryotes. This occurs during the late M to early G1 phases in which chromatin is licensed by loading of the MCM2-7 complex, an essential component of the replicative helicase. In the following S phase, only a minor fraction of chromatin-bound MCM2-7 complexes are activated to unwind the DNA. Therefore, it is proposed that the vast majority of MCM2-7 complexes license dormant origins that can be used as backups. Consistent with this idea, it has been repeatedly demonstrated that a reduction (~60%) in chromatin-bound MCM2-7 complexes has little effect on the density of active origins. In this study, however, we describe the first exception to this observation. A reduction of licensed origins due to Mcm4 chaos3 homozygosity reduces active origin density in primary embryonic fibroblasts (MEFs) in a C57BL/6J (B6) background. We found that this is associated with an intrinsically lower level of active origins in this background compared to others. B6 Mcm4 chaos3/chaos3 cells proliferate slowly due to p53-dependent upregulation of p21. In fact, the development of B6 Mcm4 chaos3/chaos3 mice is impaired and a significant fraction of them die at birth. While inactivation of p53 restores proliferation in B6 Mcm4 chaos3/chaos3 MEFs, it paradoxically does not rescue animal lethality. These findings indicate that a reduction of licensed origins may cause a more profound effect on cell types with lower densities of active origins. Moreover, p53 is required for the development of mice that suffer from intrinsic replication stress.

Journal

Mammalian GenomeSpringer Journals

Published: May 25, 2011

References

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