CHK1 cleavage in programmed cell death is intricately regulated by both caspase and non-caspase family proteases.

Background: CHK1 is an important effector kinase that regulates the cell cycle checkpoint. Previously, we showed that CHK1 is cleaved in a caspase (CASP)-dependent manner during DNA damage-induced programmed cell death (PCD) and have examined its physiological roles.

Methods And Results: In this study, we investigated the behavior of CHK1 in PCD.

DNA damage-induced CHK1 autophosphorylation at Ser296 is regulated by an intramolecular mechanism.

CHK1 regulates the DNA damage-induced checkpoint involving an ATR- or ATM- dependent pathway. In this paper, we focused on the autophosphorylation of Ser296, one of the DNA damage-induced phosphorylation sites. First, we demonstrated that the Ser296 autophosphorylation of CHK1 is mainly regulated by an intramolecular mechanism in response to DNA damage.