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The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks

The activation of Chk1 in response to stalled replication forks in Xenopus egg extracts involves a complex pathway containing ATM and Rad3-related (ATR), topoisomerase IIβ-binding protein 1 (TopBP1), Rad17, the Rad9-Hus1-Rad1 (9-1-1) complex, and Claspin. We have observed that egg extracts lacking t...

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Autores principales: Lee, Joon, Dunphy, William G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3639046/
https://www.ncbi.nlm.nih.gov/pubmed/23468519
http://dx.doi.org/10.1091/mbc.E13-01-0025
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author Lee, Joon
Dunphy, William G.
author_facet Lee, Joon
Dunphy, William G.
author_sort Lee, Joon
collection PubMed
description The activation of Chk1 in response to stalled replication forks in Xenopus egg extracts involves a complex pathway containing ATM and Rad3-related (ATR), topoisomerase IIβ-binding protein 1 (TopBP1), Rad17, the Rad9-Hus1-Rad1 (9-1-1) complex, and Claspin. We have observed that egg extracts lacking the Mre11-Rad50-Nbs1 (MRN) complex show greatly, although not completely, reduced activation of Chk1 in response to replication blockages. Depletion of both Rad17 and MRN leads to a further, essentially complete, reduction in the activation of Chk1. Thus, Rad17 and MRN act in at least a partially additive manner in promoting activation of Chk1. There was not an obvious change in the binding of RPA, ATR, Rad17, or the 9-1-1 complex to chromatin in aphidicolin (APH)-treated, MRN-depleted extracts. However, there was a substantial reduction in the binding of TopBP1. In structure–function studies of the MRN complex, we found that the Mre11 subunit is necessary for the APH-induced activation of Chk1. Moreover, a nuclease-deficient mutant of Mre11 cannot substitute for wild-type Mre11 in this process. These results indicate that the MRN complex, in particular the nuclease activity of Mre11, plays an important role in the activation of Chk1 in response to stalled replication forks. These studies reveal a previously unknown property of the MRN complex in genomic stability.
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spelling pubmed-36390462013-07-16 The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks Lee, Joon Dunphy, William G. Mol Biol Cell Articles The activation of Chk1 in response to stalled replication forks in Xenopus egg extracts involves a complex pathway containing ATM and Rad3-related (ATR), topoisomerase IIβ-binding protein 1 (TopBP1), Rad17, the Rad9-Hus1-Rad1 (9-1-1) complex, and Claspin. We have observed that egg extracts lacking the Mre11-Rad50-Nbs1 (MRN) complex show greatly, although not completely, reduced activation of Chk1 in response to replication blockages. Depletion of both Rad17 and MRN leads to a further, essentially complete, reduction in the activation of Chk1. Thus, Rad17 and MRN act in at least a partially additive manner in promoting activation of Chk1. There was not an obvious change in the binding of RPA, ATR, Rad17, or the 9-1-1 complex to chromatin in aphidicolin (APH)-treated, MRN-depleted extracts. However, there was a substantial reduction in the binding of TopBP1. In structure–function studies of the MRN complex, we found that the Mre11 subunit is necessary for the APH-induced activation of Chk1. Moreover, a nuclease-deficient mutant of Mre11 cannot substitute for wild-type Mre11 in this process. These results indicate that the MRN complex, in particular the nuclease activity of Mre11, plays an important role in the activation of Chk1 in response to stalled replication forks. These studies reveal a previously unknown property of the MRN complex in genomic stability. The American Society for Cell Biology 2013-05-01 /pmc/articles/PMC3639046/ /pubmed/23468519 http://dx.doi.org/10.1091/mbc.E13-01-0025 Text en © 2013 Lee and Dunphy. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0). “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society of Cell BD; are registered trademarks of The American Society of Cell Biology.
spellingShingle Articles
Lee, Joon
Dunphy, William G.
The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks
title The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks
title_full The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks
title_fullStr The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks
title_full_unstemmed The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks
title_short The Mre11-Rad50-Nbs1 (MRN) complex has a specific role in the activation of Chk1 in response to stalled replication forks
title_sort mre11-rad50-nbs1 (mrn) complex has a specific role in the activation of chk1 in response to stalled replication forks
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3639046/
https://www.ncbi.nlm.nih.gov/pubmed/23468519
http://dx.doi.org/10.1091/mbc.E13-01-0025
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