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Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
Published on: March 9, 2012
A role for Ran-GTP and Crm1 in blocking re-replication
Ryuji Yamaguchi1, John Newport
1Department of Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Cell
|April 8, 2003
Summary
A newly discovered metazoan-specific system prevents DNA re-replication by inactivating MCM helicase through association with exportin-1/Crm1 during S phase.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Eukaryotic cells possess regulatory mechanisms to ensure single genomic replication per cell cycle.
- These mechanisms block prereplication complex formation.
- Known regulatory mechanisms in yeast are not conserved in metazoans.
Purpose of the Study:
- Identify metazoan-specific regulatory systems controlling DNA replication.
- Investigate the role of MCM helicase and exportin-1/Crm1 in preventing re-replication.
Main Methods:
- Utilized Xenopus egg extracts for experimental analysis.
- Assessed MCM helicase inactivation via association with exportin-1/Crm1.
- Manipulated Ran-GTP levels within nuclear extracts to observe effects on MCM-chromatin association and re-replication.
Main Results:
- Soluble MCM helicase is inactivated by association with exportin-1/Crm1 during S phase in a Ran-GTP and cdk2 kinase-dependent manner.
- Reduced Ran-GTP levels permit MCM re-association with chromatin, inducing re-replication.
- Prevention of re-replication necessitates MCM-Crm1 complex formation, independent of MCM nuclear export.
Conclusions:
- A metazoan-specific regulatory system involving MCM helicase and exportin-1/Crm1 controls DNA replication.
- Exportin-1/Crm1 plays a dual role in metazoans, mediating both nuclear export and blocking DNA re-replication.
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