View in EDS

RPA-independent activation of the ATR/CHK1 pathway.

Saved in:
Bibliographic Details
Title: RPA-independent activation of the ATR/CHK1 pathway.
Authors: Huang, Min1,2 huangmin429@163.com, Zhu, Dandan1, Chen, Junjie1 jchen8@mdanderson.org
Source: Proceedings of the National Academy of Sciences of the United States of America. 2/10/2026, Vol. 123 Issue 6, p1-10. 22p.
Subjects: Replication fork, Serine/threonine kinases, DNA repair, DNA damage, Cellular signal transduction
Abstract: The ATR/CHK1 pathway governs a crucial intra-S-phase checkpoint that safeguards genome stability under replication stress by stabilizing stalled replication forks and ensuring high-fidelity DNA replication. Traditionally, activation of this pathway is thought to rely on replication protein A (RPA)-coated single-stranded DNA, which recruits the ATR–ATRIP complex to sites of stalling fork, positioning RPA as essential for ATR signaling. In this study, we report a surprising and previously unrecognized phenomenon: acute depletion of RPA2 triggers robust ATR/CHK1 activation through an RPA-independent mechanism. Using 293A and RPE-1 cells engineered with an inducible RPA2-dTAG degron system, we observed increased phosphorylation of CHK1 at Ser296 and Ser345 in the absence of RPA. Notably, this elevated CHK1 phosphorylation was abolished by ATR inhibition, confirming its dependence on ATR kinase activity. Mechanistic analyses further revealed that this RPA-independent activation requires the checkpoint mediators RAD9 and TOPBP1. These findings uncover dual mechanisms, both RPA-dependent and -independent, of ATR/CHK1 pathway activation, highlighting a robust and flexible replication stress response network that preserves genome integrity even when canonical signaling is disrupted. [ABSTRACT FROM AUTHOR]
Copyright of Proceedings of the National Academy of Sciences of the United States of America is the property of National Academy of Sciences and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
FullText Text:
  Availability: 0
Header DbId: egs
DbLabel: Engineering Source
An: 191672536
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
IllustrationInfo
Items – Name: Title
  Label: Title
  Group: Ti
  Data: RPA-independent activation of the ATR/CHK1 pathway.
– Name: Author
  Label: Authors
  Group: Au
  Data: <searchLink fieldCode="AR" term="%22Huang%2C+Min%22">Huang, Min</searchLink><relatesTo>1,2</relatesTo><i> huangmin429@163.com</i><br /><searchLink fieldCode="AR" term="%22Zhu%2C+Dandan%22">Zhu, Dandan</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Chen%2C+Junjie%22">Chen, Junjie</searchLink><relatesTo>1</relatesTo><i> jchen8@mdanderson.org</i>
– Name: TitleSource
  Label: Source
  Group: Src
  Data: <searchLink fieldCode="JN" term="%22Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America%22">Proceedings of the National Academy of Sciences of the United States of America</searchLink>. 2/10/2026, Vol. 123 Issue 6, p1-10. 22p.
– Name: Subject
  Label: Subjects
  Group: Su
  Data: <searchLink fieldCode="DE" term="%22Replication+fork%22">Replication fork</searchLink><br /><searchLink fieldCode="DE" term="%22Serine%2Fthreonine+kinases%22">Serine/threonine kinases</searchLink><br /><searchLink fieldCode="DE" term="%22DNA+repair%22">DNA repair</searchLink><br /><searchLink fieldCode="DE" term="%22DNA+damage%22">DNA damage</searchLink><br /><searchLink fieldCode="DE" term="%22Cellular+signal+transduction%22">Cellular signal transduction</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The ATR/CHK1 pathway governs a crucial intra-S-phase checkpoint that safeguards genome stability under replication stress by stabilizing stalled replication forks and ensuring high-fidelity DNA replication. Traditionally, activation of this pathway is thought to rely on replication protein A (RPA)-coated single-stranded DNA, which recruits the ATR–ATRIP complex to sites of stalling fork, positioning RPA as essential for ATR signaling. In this study, we report a surprising and previously unrecognized phenomenon: acute depletion of RPA2 triggers robust ATR/CHK1 activation through an RPA-independent mechanism. Using 293A and RPE-1 cells engineered with an inducible RPA2-dTAG degron system, we observed increased phosphorylation of CHK1 at Ser296 and Ser345 in the absence of RPA. Notably, this elevated CHK1 phosphorylation was abolished by ATR inhibition, confirming its dependence on ATR kinase activity. Mechanistic analyses further revealed that this RPA-independent activation requires the checkpoint mediators RAD9 and TOPBP1. These findings uncover dual mechanisms, both RPA-dependent and -independent, of ATR/CHK1 pathway activation, highlighting a robust and flexible replication stress response network that preserves genome integrity even when canonical signaling is disrupted. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Proceedings of the National Academy of Sciences of the United States of America is the property of National Academy of Sciences and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=191672536
RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1073/pnas.2524246123
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 22
        StartPage: 1
    Subjects:
      – SubjectFull: Replication fork
        Type: general
      – SubjectFull: Serine/threonine kinases
        Type: general
      – SubjectFull: DNA repair
        Type: general
      – SubjectFull: DNA damage
        Type: general
      – SubjectFull: Cellular signal transduction
        Type: general
    Titles:
      – TitleFull: RPA-independent activation of the ATR/CHK1 pathway.
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Huang, Min
      – PersonEntity:
          Name:
            NameFull: Zhu, Dandan
      – PersonEntity:
          Name:
            NameFull: Chen, Junjie
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 10
              M: 02
              Text: 2/10/2026
              Type: published
              Y: 2026
          Identifiers:
            – Type: issn-print
              Value: 00278424
          Numbering:
            – Type: volume
              Value: 123
            – Type: issue
              Value: 6
          Titles:
            – TitleFull: Proceedings of the National Academy of Sciences of the United States of America
              Type: main
ResultId 1