Regulators of cyclin-dependent kinases are crucial for maintaining genome integrity in S phase

TLDR

Genome integrity is essential for cells, and the kinases WEE1 and CHK1 act as key negative regulators of CDK1 and CDK2. The study screened a human cell line with a kinome siRNA library to identify key regulators of genomic integrity. The authors performed a kinome siRNA screen in a human cell line. WEE1 and CHK1 were identified as key regulators; depletion of WEE1 induces S‑phase DNA damage dependent on CDK1/2 and replication factors, while CHK1 inhibition causes damage that requires CDC25A, and co‑depletion of CDC25A rescues CHK1‑deficient proliferation, demonstrating that WEE1 and CHK1 jointly safeguard genome integrity during replication.

Abstract

Maintenance of genome integrity is of critical importance to cells. To identify key regulators of genomic integrity, we screened a human cell line with a kinome small interfering RNA library. WEE1, a major regulator of mitotic entry, and CHK1 were among the genes identified. Both kinases are important negative regulators of CDK1 and -2. Strikingly, WEE1 depletion rapidly induced DNA damage in S phase in newly replicated DNA, which was accompanied by a marked increase in single-stranded DNA. This DNA damage is dependent on CDK1 and -2 as well as the replication proteins MCM2 and CDT1 but not CDC25A. Conversely, DNA damage after CHK1 inhibition is highly dependent on CDC25A. Furthermore, the inferior proliferation of CHK1-depleted cells is improved substantially by codepletion of CDC25A. We conclude that the mitotic kinase WEE1 and CHK1 jointly maintain balanced cellular control of Cdk activity during normal DNA replication, which is crucial to prevent the generation of harmful DNA lesions during replication.