Tag: Chk1

ATR is a key protein kinase that protects cells from replication stress and DNA damage. Explore how ATR detects single-stranded DNA, stabilizes replication forks, activates CHK1, and maintains genome stability.

Replication stress occurs when DNA replication forks stall or collapse, generating genomic instability and driving tumour evolution. Through ATR–CHK1 signalling, fork protection and homologous recombination repair, cells stabilise damaged forks and prevent catastrophic chromosomal breakage.

Cdc25 phosphatases activate CDKs to drive both the G1–S and G2–M transitions. By removing inhibitory phosphates from CDK1 and CDK2, Cdc25 triggers DNA replication and mitotic entry. Checkpoint kinases such as Chk1 inhibit Cdc25 during DNA damage, while Cdc25 overexpression promotes genomic instability and contributes to tumour progression.