DNA-PKcs is required to maintain stability of Chk1 and Claspin for optimal replication stress response.

Abstract

The ataxia telangiectasia mutated and Rad3-related (ATR)-checkpoint kinase 1 (Chk1) axis is the major signaling pathway activated in response to replication stress and is essential for the intra-S checkpoint. ATR phosphorylates and activates a number of molecules to coordinate cell cycle progression. Chk1 is the major effector downstream from ATR and plays a critical role in intra-S checkpoint on replication stress. Activation of Chk1 kinase also requires its association with Claspin, an adaptor protein essential for Chk1 protein stability, recruitment and ATR-dependent Chk1 phosphorylation. We have previously reported that, on replication stress, the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is rapidly phosphorylated by ATR at the stalled replication forks and is required for cellular resistance to replication stresses although the impact of DNA-PKcs onto the ATR signaling pathway remains elusive. Here we report that ATR-dependent Chk1 phosphorylation and Chk1 signaling are compromised in the absence of DNA-PKcs. Our investigation reveals that DNA-PKcs is required to maintain Chk1-Claspin complex stability and transcriptional regulation of Claspin expression. The impaired Chk1 activity results in a defective intra-S checkpoint response in DNA-PKcs-deficient cells. Taken together, these results suggest that DNA-PKcs, in addition to its direct role in DNA damage repair, facilitates ATR-Chk1 signaling pathway in response to replication stress.

• Authors: Yu-Fen Lin, Hung-Ying Shih, Zengfu Shang, Shinji Matsunaga, Benjamin Pc Chen
• Journal: Nucleic acids research (Nucleic Acids Res) Vol. 42 Issue 7 Pg. 4463-73 (Apr 2014) ISSN: 1362-4962 [Electronic] England
• PMID: 24500207 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Adaptor Proteins, Signal Transducing
• CLSPN protein, human
• Chromatin
• Nuclear Proteins
• Protein Kinases
• ATR protein, human
• Ataxia Telangiectasia Mutated Proteins
• CHEK1 protein, human
• Checkpoint Kinase 1
• DNA-Activated Protein Kinase
• PRKDC protein, human

Topics

• Adaptor Proteins, Signal Transducing (metabolism)
• Ataxia Telangiectasia Mutated Proteins (metabolism)
• Cell Line, Tumor
• Checkpoint Kinase 1
• Chromatin (metabolism)
• DNA Replication
• DNA-Activated Protein Kinase (genetics, physiology)
• Humans
• Mutation
• Nuclear Proteins (genetics, physiology)
• Protein Kinases (metabolism)
• Protein Stability
• S Phase Cell Cycle Checkpoints
• Stress, Physiological (genetics)