CHEK1

CHEK1 (Checkpoint Kinase 1) is a protein encoded by the *CHEK1* gene in humans, located on chromosome 10 (10q24.33). It belongs to the family of serine/threonine protein kinases, which play critical roles in cell cycle regulation, DNA damage response, and apoptosis. CHEK1 is primarily involved in the cellular checkpoint mechanisms that ensure proper DNA replication and repair before cell division proceeds.

The gene is activated in response to DNA damage, particularly single-strand breaks, by interacting with proteins such as ATM (Ataxia Telangiectasia Mutated) and ATR (ATM and Rad3-related). Upon activation, CHEK1 phosphorylates and activates downstream targets, including CDC25A, BRCA1, and p53, which help halt the cell cycle to allow for DNA repair or induce apoptosis if damage is irreparable. This pathway is essential for maintaining genomic stability and preventing the propagation of mutations.

Mutations in the *CHEK1* gene have been associated with increased susceptibility to cancer, particularly in breast, ovarian, and prostate cancers. Some hereditary cancer syndromes, such as Li-Fraumeni syndrome, have been linked to defective CHEK1 function. Additionally, CHEK1 has been studied as a potential therapeutic target in cancer treatment, as its inhibition can disrupt tumor cell proliferation.

CHEK1 is also involved in stress responses, including those triggered by oxidative damage and metabolic stress, though its exact mechanisms in these contexts remain under investigation. Research continues to explore its role in aging, stem cell maintenance, and other cellular processes beyond DNA repair.