Abstract
Claspin is required for the phosphorylation and activation of the Chk1 protein kinase by ATR during DNA replication and in response to DNA damage. This checkpoint pathway plays a critical role in the resistance of cells to genotoxic stress. Here, we show that human Claspin is cleaved by caspase-7 during the initiation of apoptosis. In cells, induction of DNA damage by etoposide at first produced rapid phosphorylation of Chk1 at a site targeted by ATR. Subsequently, etoposide caused activation of caspase-7, cleavage of Claspin, and dephosphorylation of Chk1. In apoptotic cell extracts, Claspin was cleaved by caspase-7 at a single aspartate residue into a large N-terminal fragment and a smaller C-terminal fragment that contain different functional domains. The large N-terminal fragment was heavily phosphorylated in a human cell-free system in response to double-stranded DNA oligonucleotides, and this fragment retained Chk1 binding activity. In contrast, the smaller C-terminal fragment did not bind Chk1, but did associate with DNA and inhibited the DNA-dependent phosphorylation of Chk1 associated with its activation. These results indicate that cleavage of Claspin by caspase-7 inactivates the Chk1 signaling pathway. This mechanism may regulate the balance between cell cycle arrest and induction of apoptosis during the response to genotoxic stress.
| Original language | English |
|---|---|
| Pages (from-to) | 35337-35345 |
| Number of pages | 9 |
| Journal | Journal of Biological Chemistry |
| Volume | 280 |
| Issue number | 42 |
| Early online date | 25 Aug 2005 |
| DOIs | |
| Publication status | Published - 21 Oct 2005 |
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Cleavage of claspin by caspase-7 during apoptosis inhibits the Chk1 pathway. / Clarke, Catriona A.L.; Bennett, Lara N.; Clarke, Paul R. (Lead / Corresponding author).
In: Journal of Biological Chemistry, Vol. 280, No. 42, 21.10.2005, p. 35337-35345.Research output: Contribution to journal › Article
TY - JOUR
T1 - Cleavage of claspin by caspase-7 during apoptosis inhibits the Chk1 pathway
AU - Clarke, Catriona A.L.
AU - Bennett, Lara N.
AU - Clarke, Paul R.
PY - 2005/10/21
Y1 - 2005/10/21
N2 - Claspin is required for the phosphorylation and activation of the Chk1 protein kinase by ATR during DNA replication and in response to DNA damage. This checkpoint pathway plays a critical role in the resistance of cells to genotoxic stress. Here, we show that human Claspin is cleaved by caspase-7 during the initiation of apoptosis. In cells, induction of DNA damage by etoposide at first produced rapid phosphorylation of Chk1 at a site targeted by ATR. Subsequently, etoposide caused activation of caspase-7, cleavage of Claspin, and dephosphorylation of Chk1. In apoptotic cell extracts, Claspin was cleaved by caspase-7 at a single aspartate residue into a large N-terminal fragment and a smaller C-terminal fragment that contain different functional domains. The large N-terminal fragment was heavily phosphorylated in a human cell-free system in response to double-stranded DNA oligonucleotides, and this fragment retained Chk1 binding activity. In contrast, the smaller C-terminal fragment did not bind Chk1, but did associate with DNA and inhibited the DNA-dependent phosphorylation of Chk1 associated with its activation. These results indicate that cleavage of Claspin by caspase-7 inactivates the Chk1 signaling pathway. This mechanism may regulate the balance between cell cycle arrest and induction of apoptosis during the response to genotoxic stress.
AB - Claspin is required for the phosphorylation and activation of the Chk1 protein kinase by ATR during DNA replication and in response to DNA damage. This checkpoint pathway plays a critical role in the resistance of cells to genotoxic stress. Here, we show that human Claspin is cleaved by caspase-7 during the initiation of apoptosis. In cells, induction of DNA damage by etoposide at first produced rapid phosphorylation of Chk1 at a site targeted by ATR. Subsequently, etoposide caused activation of caspase-7, cleavage of Claspin, and dephosphorylation of Chk1. In apoptotic cell extracts, Claspin was cleaved by caspase-7 at a single aspartate residue into a large N-terminal fragment and a smaller C-terminal fragment that contain different functional domains. The large N-terminal fragment was heavily phosphorylated in a human cell-free system in response to double-stranded DNA oligonucleotides, and this fragment retained Chk1 binding activity. In contrast, the smaller C-terminal fragment did not bind Chk1, but did associate with DNA and inhibited the DNA-dependent phosphorylation of Chk1 associated with its activation. These results indicate that cleavage of Claspin by caspase-7 inactivates the Chk1 signaling pathway. This mechanism may regulate the balance between cell cycle arrest and induction of apoptosis during the response to genotoxic stress.
UR - http://www.scopus.com/inward/record.url?scp=27444446948&partnerID=8YFLogxK
U2 - 10.1074/jbc.M506460200
DO - 10.1074/jbc.M506460200
M3 - Article
C2 - 16123041
AN - SCOPUS:27444446948
VL - 280
SP - 35337
EP - 35345
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 42
ER -