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Updated: Jan 21, 2026

Evaluation of the Spindle Assembly Checkpoint Integrity in Mouse Oocytes
Published on: September 13, 2022
Basal CHK1 activity safeguards its stability to maintain intrinsic S-phase checkpoint functions
Jone Michelena1, Marco Gatti1, Federico Teloni1,2
1Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland.
Abstract:
The DNA replication machinery frequently encounters impediments that slow replication fork progression and threaten timely and error-free replication. The CHK1 protein kinase is essential to deal with replication stress (RS) and ensure genome integrity and cell survival, yet how basal levels and activity of CHK1 are maintained under physiological, unstressed conditions is not well understood. Here, we reveal that CHK1 stability is controlled by its steady-state activity during unchallenged cell proliferation. This autoactivatory mechanism, which depends on ATR and its coactivator ETAA1 and is tightly associated with CHK1 autophosphorylation at S296, counters CHK1 ubiquitylation and proteasomal degradation, thereby preventing attenuation of S-phase checkpoint functions and a compromised capacity to respond to RS. Based on these findings, we propose that steady-state CHK1 activity safeguards its stability to maintain intrinsic checkpoint functions and ensure genome integrity and cell survival.
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