TY - JOUR
T1 - Snm1B/Apollo mediates replication fork collapse and S phase checkpoint activation in response to DNA interstrand cross-links
AU - Bae, J. B.
AU - Mukhopadhyay, S. S.
AU - Liu, L.
AU - Zhang, N.
AU - Tan, J.
AU - Akhter, S.
AU - Liu, X.
AU - Shen, X.
AU - Li, L.
AU - Legerski, R. J.
N1 - Funding Information:
We thank Tanya Paull and Steve Patrick for the gift of MRN protein, and Jeffrey Parvin for the gift of FancD2 protein. This work was su pported by NCI Grants CA052461 and CA097175. DNA sequencing resources were supported by the Cancer Center Support (Core) Grant CA16672.
PY - 2008/8/28
Y1 - 2008/8/28
N2 - The removal of DNA interstrand cross-links (ICLs) has proven to be notoriously complicated due to the involvement of multiple pathways of DNA repair, which include the Fanconi anemia/BRCA pathway, homologous recombination and components of the nucleotide excision and mismatch repair pathways. Members of the SNM1 gene family have also been shown to have a role in mediating cellular resistance to ICLs, although their precise function has remained elusive. Here, we show that knockdown of Snm1B/Apollo in human cells results in hypersensitivity to mitomycin C (MMC), but not to IR. We also show that Snm1B-deficient cells exhibit a defective S phase checkpoint in response to MMC, but not to IR, and this finding may account for the specific sensitivity to the cross-linking drug. Interestingly, although previous studies have largely implicated ATR as the major kinase activated in response to ICLs, we show that it is activation of the ATM-mediated checkpoint that is defective in Snm1B-deficient cells. The requirement for Snm1B in ATM checkpoint activation specifically after ICL damage is correlated with its role in promoting double-strand break formation, and thus replication fork collapse. Consistent with this result Snm1B was found to interact directly with Mus81-Eme1, an endonuclease previously implicated in fork collapse. In addition, we also show that Snm1B interacts with the Mre11-Rad50-Nbs1 (MRN) complex and with FancD2 further substantiating its role as a checkpoint/DNA repair protein.
AB - The removal of DNA interstrand cross-links (ICLs) has proven to be notoriously complicated due to the involvement of multiple pathways of DNA repair, which include the Fanconi anemia/BRCA pathway, homologous recombination and components of the nucleotide excision and mismatch repair pathways. Members of the SNM1 gene family have also been shown to have a role in mediating cellular resistance to ICLs, although their precise function has remained elusive. Here, we show that knockdown of Snm1B/Apollo in human cells results in hypersensitivity to mitomycin C (MMC), but not to IR. We also show that Snm1B-deficient cells exhibit a defective S phase checkpoint in response to MMC, but not to IR, and this finding may account for the specific sensitivity to the cross-linking drug. Interestingly, although previous studies have largely implicated ATR as the major kinase activated in response to ICLs, we show that it is activation of the ATM-mediated checkpoint that is defective in Snm1B-deficient cells. The requirement for Snm1B in ATM checkpoint activation specifically after ICL damage is correlated with its role in promoting double-strand break formation, and thus replication fork collapse. Consistent with this result Snm1B was found to interact directly with Mus81-Eme1, an endonuclease previously implicated in fork collapse. In addition, we also show that Snm1B interacts with the Mre11-Rad50-Nbs1 (MRN) complex and with FancD2 further substantiating its role as a checkpoint/DNA repair protein.
KW - ATM
KW - Cell cycle checkpoint
KW - Interstrand cross-links
KW - Snm1B/Apollo
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U2 - 10.1038/onc.2008.139
DO - 10.1038/onc.2008.139
M3 - Article
C2 - 18469862
AN - SCOPUS:50649091340
SN - 0950-9232
VL - 27
SP - 5045
EP - 5056
JO - Oncogene
JF - Oncogene
IS - 37
ER -