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Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis

The Tim (Timeless)–Tipin complex has been proposed to maintain genome stability by facilitating ATR-mediated Chk1 activation. However, as a replisome component, Tim–Tipin has also been suggested to couple DNA unwinding to synthesis, an activity expected to suppress single-stranded DNA (ssDNA) accumu...

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Detalles Bibliográficos
Autores principales: Smith, Kevin D., Fu, Michael A., Brown, Eric J.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2009
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2762102/
https://www.ncbi.nlm.nih.gov/pubmed/19805627
http://dx.doi.org/10.1083/jcb.200905006
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author Smith, Kevin D.
Fu, Michael A.
Brown, Eric J.
author_facet Smith, Kevin D.
Fu, Michael A.
Brown, Eric J.
author_sort Smith, Kevin D.
collection PubMed
description The Tim (Timeless)–Tipin complex has been proposed to maintain genome stability by facilitating ATR-mediated Chk1 activation. However, as a replisome component, Tim–Tipin has also been suggested to couple DNA unwinding to synthesis, an activity expected to suppress single-stranded DNA (ssDNA) accumulation and limit ATR–Chk1 pathway engagement. We now demonstrate that Tim–Tipin depletion is sufficient to increase ssDNA accumulation at replication forks and stimulate ATR activity during otherwise unperturbed DNA replication. Notably, suppression of the ATR–Chk1 pathway in Tim–Tipin-deficient cells completely abrogates nucleotide incorporation in S phase, indicating that the ATR-dependent response to Tim–Tipin depletion is indispensible for continued DNA synthesis. Replication failure in ATR/Tim-deficient cells is strongly associated with synergistic increases in H2AX phosphorylation and DNA double-strand breaks, suggesting that ATR pathway activation preserves fork stability in instances of Tim–Tipin dysfunction. Together, these experiments indicate that the Tim–Tipin complex stabilizes replication forks both by preventing the accumulation of ssDNA upstream of ATR–Chk1 function and by facilitating phosphorylation of Chk1 by ATR.
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spelling pubmed-27621022010-04-05 Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis Smith, Kevin D. Fu, Michael A. Brown, Eric J. J Cell Biol Research Articles The Tim (Timeless)–Tipin complex has been proposed to maintain genome stability by facilitating ATR-mediated Chk1 activation. However, as a replisome component, Tim–Tipin has also been suggested to couple DNA unwinding to synthesis, an activity expected to suppress single-stranded DNA (ssDNA) accumulation and limit ATR–Chk1 pathway engagement. We now demonstrate that Tim–Tipin depletion is sufficient to increase ssDNA accumulation at replication forks and stimulate ATR activity during otherwise unperturbed DNA replication. Notably, suppression of the ATR–Chk1 pathway in Tim–Tipin-deficient cells completely abrogates nucleotide incorporation in S phase, indicating that the ATR-dependent response to Tim–Tipin depletion is indispensible for continued DNA synthesis. Replication failure in ATR/Tim-deficient cells is strongly associated with synergistic increases in H2AX phosphorylation and DNA double-strand breaks, suggesting that ATR pathway activation preserves fork stability in instances of Tim–Tipin dysfunction. Together, these experiments indicate that the Tim–Tipin complex stabilizes replication forks both by preventing the accumulation of ssDNA upstream of ATR–Chk1 function and by facilitating phosphorylation of Chk1 by ATR. The Rockefeller University Press 2009-10-05 /pmc/articles/PMC2762102/ /pubmed/19805627 http://dx.doi.org/10.1083/jcb.200905006 Text en © 2009 Smith et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
spellingShingle Research Articles
Smith, Kevin D.
Fu, Michael A.
Brown, Eric J.
Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis
title Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis
title_full Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis
title_fullStr Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis
title_full_unstemmed Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis
title_short Tim–Tipin dysfunction creates an indispensible reliance on the ATR–Chk1 pathway for continued DNA synthesis
title_sort tim–tipin dysfunction creates an indispensible reliance on the atr–chk1 pathway for continued dna synthesis
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2762102/
https://www.ncbi.nlm.nih.gov/pubmed/19805627
http://dx.doi.org/10.1083/jcb.200905006
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