Methylator-induced, Mismatch Repair-dependent G2 Arrest Is Activated through Chk1 and Chk2

AUTOR(ES)

Adamson, Aaron W.

FONTE

The American Society for Cell Biology

RESUMO

SN1 DNA methylating agents such as the nitrosourea N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) elicit a G2/M checkpoint response via a mismatch repair (MMR) system-dependent mechanism; however, the exact nature of the mechanism governing MNNG-induced G2/M arrest and how MMR mechanistically participates in this process are unknown. Here, we show that MNNG exposure results in activation of the cell cycle checkpoint kinases ATM, Chk1, and Chk2, each of which has been implicated in the triggering of the G2/M checkpoint response. We document that MNNG induces a robust, dose-dependent G2 arrest in MMR and ATM-proficient cells, whereas this response is abrogated in MMR-deficient cells and attenuated in ATM-deficient cells treated with moderate doses of MNNG. Pharmacological and RNA interference approaches indicated that Chk1 and Chk2 are both required components for normal MNNG-induced G2 arrest. MNNG-induced nuclear exclusion of the cell cycle regulatory phosphatase Cdc25C occurred in an MMR-dependent manner and was compromised in cells lacking ATM. Finally, both Chk1 and Chk2 interact with the MMR protein MSH2, and this interaction is enhanced after MNNG exposure, supporting the notion that the MMR system functions as a molecular scaffold at the sites of DNA damage that facilitates activation of these kinases.

Documentos Relacionados

• Mismatch repair-dependent G2 checkpoint induced by low doses of SN1 type methylating agents requires the ATR kinase
• Geminin Deficiency Causes a Chk1-dependent G2 Arrest in Xenopus
• p73 induction after DNA damage is regulated by checkpoint kinases Chk1 and Chk2
• Chk2 Activation and Phosphorylation-Dependent Oligomerization
• Chk2 is dispensable for p53-mediated G1 arrest but is required for a latent p53-mediated apoptotic response