O6-methylguanine-induced cell death involves exonuclease 1 as well as DNA mismatch recognition in vivo

Joanna Klapacz, Lisiane B. Meira, David G. Luchetti, Jennifer A. Calvo, Roderick T. Bronson, Winfried Edelmann, Leona D. Samson

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Alkylation-induced O6-methylguanine (O6MeG) DNA lesions can be mutagenic or cytotoxic if unrepaired by the O6MeG-DNA methyltransferase (Mgmt) protein. O6MeG pairs with T during DNA replication, and if the O6MeG:T mismatch persists, a G:C to A:T transition mutation is fixed at the next replication cycle. O6MeG:T mismatch detection by MutSα and MutLα leads to apoptotic cell death, but the mechanism by which this occurs has been elusive. To explore how mismatch repair mediates O6MeG-dependent apoptosis, we used an Mgmt-null mouse model combined with either the Msh6-null mutant (defective in mismatch recognition) or the Exo1-null mutant (impaired in the excision step of mismatch repair). Mouse embryonic fibroblasts and bone marrow cells derived from Mgmt-null mice were much more alkylation-sensitive than wild type, as expected. However, ablation of either Msh6 or Exo1 function rendered these Mgmt-null cells just as resistant to alkylation-induced cytotoxicity as wild-type cells. Rapidly proliferating tissues in Mgmt-null mice (bone marrow, thymus, and spleen) are extremely sensitive to apoptosis induced by O6MeG- producing agents. Here, we show that ablation of either Msh6 or Exo1 function in the Mgmt-null mouse renders these rapidly proliferating tissues alkylation-resistant. However, whereas the Msh6 defect confers total alkylation resistance, the Exo1 defect leads to a variable tissue-specific alkylation resistance phenotype. Our results indicate that Exo1 plays an important role in the induction of apoptosis by unrepaired O6MeGs.

Original languageEnglish (US)
Pages (from-to)576-581
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume106
Issue number2
DOIs
StatePublished - Jan 13 2009

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Alkylation
Cell Death
DNA
DNA Mismatch Repair
Apoptosis
Thymus Gland
Spleen
Bone Marrow
Protein Methyltransferases
Null Lymphocytes
exodeoxyribonuclease I
O-(6)-methylguanine
DNA Replication
Bone Marrow Cells
Fibroblasts
Phenotype
Mutation

Keywords

  • Alkylation resistance
  • Apoptosis
  • DNA alkylation
  • Mgmt
  • N-methyl-N′- nitrosourea (MNU)

ASJC Scopus subject areas

  • General

Cite this

O6-methylguanine-induced cell death involves exonuclease 1 as well as DNA mismatch recognition in vivo. / Klapacz, Joanna; Meira, Lisiane B.; Luchetti, David G.; Calvo, Jennifer A.; Bronson, Roderick T.; Edelmann, Winfried; Samson, Leona D.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 106, No. 2, 13.01.2009, p. 576-581.

Research output: Contribution to journalArticle

Klapacz, Joanna ; Meira, Lisiane B. ; Luchetti, David G. ; Calvo, Jennifer A. ; Bronson, Roderick T. ; Edelmann, Winfried ; Samson, Leona D. / O6-methylguanine-induced cell death involves exonuclease 1 as well as DNA mismatch recognition in vivo. In: Proceedings of the National Academy of Sciences of the United States of America. 2009 ; Vol. 106, No. 2. pp. 576-581.
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abstract = "Alkylation-induced O6-methylguanine (O6MeG) DNA lesions can be mutagenic or cytotoxic if unrepaired by the O6MeG-DNA methyltransferase (Mgmt) protein. O6MeG pairs with T during DNA replication, and if the O6MeG:T mismatch persists, a G:C to A:T transition mutation is fixed at the next replication cycle. O6MeG:T mismatch detection by MutSα and MutLα leads to apoptotic cell death, but the mechanism by which this occurs has been elusive. To explore how mismatch repair mediates O6MeG-dependent apoptosis, we used an Mgmt-null mouse model combined with either the Msh6-null mutant (defective in mismatch recognition) or the Exo1-null mutant (impaired in the excision step of mismatch repair). Mouse embryonic fibroblasts and bone marrow cells derived from Mgmt-null mice were much more alkylation-sensitive than wild type, as expected. However, ablation of either Msh6 or Exo1 function rendered these Mgmt-null cells just as resistant to alkylation-induced cytotoxicity as wild-type cells. Rapidly proliferating tissues in Mgmt-null mice (bone marrow, thymus, and spleen) are extremely sensitive to apoptosis induced by O6MeG- producing agents. Here, we show that ablation of either Msh6 or Exo1 function in the Mgmt-null mouse renders these rapidly proliferating tissues alkylation-resistant. However, whereas the Msh6 defect confers total alkylation resistance, the Exo1 defect leads to a variable tissue-specific alkylation resistance phenotype. Our results indicate that Exo1 plays an important role in the induction of apoptosis by unrepaired O6MeGs.",
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T1 - O6-methylguanine-induced cell death involves exonuclease 1 as well as DNA mismatch recognition in vivo

AU - Klapacz, Joanna

AU - Meira, Lisiane B.

AU - Luchetti, David G.

AU - Calvo, Jennifer A.

AU - Bronson, Roderick T.

AU - Edelmann, Winfried

AU - Samson, Leona D.

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AB - Alkylation-induced O6-methylguanine (O6MeG) DNA lesions can be mutagenic or cytotoxic if unrepaired by the O6MeG-DNA methyltransferase (Mgmt) protein. O6MeG pairs with T during DNA replication, and if the O6MeG:T mismatch persists, a G:C to A:T transition mutation is fixed at the next replication cycle. O6MeG:T mismatch detection by MutSα and MutLα leads to apoptotic cell death, but the mechanism by which this occurs has been elusive. To explore how mismatch repair mediates O6MeG-dependent apoptosis, we used an Mgmt-null mouse model combined with either the Msh6-null mutant (defective in mismatch recognition) or the Exo1-null mutant (impaired in the excision step of mismatch repair). Mouse embryonic fibroblasts and bone marrow cells derived from Mgmt-null mice were much more alkylation-sensitive than wild type, as expected. However, ablation of either Msh6 or Exo1 function rendered these Mgmt-null cells just as resistant to alkylation-induced cytotoxicity as wild-type cells. Rapidly proliferating tissues in Mgmt-null mice (bone marrow, thymus, and spleen) are extremely sensitive to apoptosis induced by O6MeG- producing agents. Here, we show that ablation of either Msh6 or Exo1 function in the Mgmt-null mouse renders these rapidly proliferating tissues alkylation-resistant. However, whereas the Msh6 defect confers total alkylation resistance, the Exo1 defect leads to a variable tissue-specific alkylation resistance phenotype. Our results indicate that Exo1 plays an important role in the induction of apoptosis by unrepaired O6MeGs.

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