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Chk1 loss creates replication barriers that compromise cell survival independently of excess origin firing
Author(s) -
González Besteiro Marina A,
Calzetta Nicolás L,
Loureiro Sofía M,
Habif Martín,
Bétous Rémy,
Pillaire MarieJeanne,
Maffia Antonio,
Sabbioneda Simone,
Hoffmann JeanSébastien,
Gottifredi Vanesa
Publication year - 2019
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2018101284
Subject(s) - biology , replication (statistics) , compromise , dna replication , cell survival , genetics , microbiology and biotechnology , computational biology , dna , virology , cell culture , social science , sociology
The effectiveness of checkpoint kinase 1 (Chk1) inhibitors at killing cancer cells is considered to be fully dependent on their effect on DNA replication initiation. Chk1 inhibition boosts origin firing, presumably limiting the availability of nucleotides and in turn provoking the slowdown and subsequent collapse of forks, thus decreasing cell viability. Here we show that slow fork progression in Chk1‐inhibited cells is not an indirect effect of excess new origin firing. Instead, fork slowdown results from the accumulation of replication barriers, whose bypass is impeded by CDK ‐dependent phosphorylation of the specialized DNA polymerase eta (Polη). Also in contrast to the linear model, the accumulation of DNA damage in Chk1‐deficient cells depends on origin density but is largely independent of fork speed. Notwithstanding this, origin dysregulation contributes only mildly to the poor proliferation rates of Chk1‐depleted cells. Moreover, elimination of replication barriers by downregulation of helicase components, but not their bypass by Polη, improves cell survival. Our results thus shed light on the molecular basis of the sensitivity of tumors to Chk1 inhibition.