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The Major Replicative Histone Chaperone CAF-1 Suppresses the Activity of the DNA Mismatch Repair System in the Cytotoxic Response to a DNA-methylating Agent

2016; Elsevier BV; Volume: 291; Issue: 53 Linguagem: Inglês

10.1074/jbc.m116.760561

1083-351X

Lyudmila Y. Kadyrova, Basanta K. Dahal, Farid A. Kadyrov,

Cancer Genomics and Diagnostics

The DNA mismatch repair (MMR) system corrects DNA mismatches in the genome. It is also required for the cytotoxic response of O6-methylguanine-DNA methyltransferase (MGMT)-deficient mammalian cells and yeast mgt1Δ rad52Δ cells to treatment with Sn1-type methylating agents, which produce cytotoxic O6-methylguanine (O6-mG) DNA lesions. Specifically, an activity of the MMR system causes degradation of irreparable O6-mG-T mispair-containing DNA, triggering cell death; this process forms the basis of treatments of MGMT-deficient cancers with Sn1-type methylating drugs. Recent research supports the view that degradation of irreparable O6-mG-T mispair-containing DNA by the MMR system and CAF-1-dependent packaging of the newly replicated DNA into nucleosomes are two concomitant processes that interact with each other. Here, we studied whether CAF-1 modulates the activity of the MMR system in the cytotoxic response to Sn1-type methylating agents. We found that CAF-1 suppresses the activity of the MMR system in the cytotoxic response of yeast mgt1Δ rad52Δ cells to the prototypic Sn1-type methylating agent N-methyl-N′-nitro-N-nitrosoguanidine. We also report evidence that in human MGMT-deficient cell-free extracts, CAF-1-dependent packaging of irreparable O6-mG-T mispair-containing DNA into nucleosomes suppresses its degradation by the MMR system. Taken together, these findings suggest that CAF-1-dependent incorporation of irreparable O6-mG-T mispair-containing DNA into nucleosomes suppresses its degradation by the MMR system, thereby defending the cell against killing by the Sn1-type methylating agent. The DNA mismatch repair (MMR) system corrects DNA mismatches in the genome. It is also required for the cytotoxic response of O6-methylguanine-DNA methyltransferase (MGMT)-deficient mammalian cells and yeast mgt1Δ rad52Δ cells to treatment with Sn1-type methylating agents, which produce cytotoxic O6-methylguanine (O6-mG) DNA lesions. Specifically, an activity of the MMR system causes degradation of irreparable O6-mG-T mispair-containing DNA, triggering cell death; this process forms the basis of treatments of MGMT-deficient cancers with Sn1-type methylating drugs. Recent research supports the view that degradation of irreparable O6-mG-T mispair-containing DNA by the MMR system and CAF-1-dependent packaging of the newly replicated DNA into nucleosomes are two concomitant processes that interact with each other. Here, we studied whether CAF-1 modulates the activity of the MMR system in the cytotoxic response to Sn1-type methylating agents. We found that CAF-1 suppresses the activity of the MMR system in the cytotoxic response of yeast mgt1Δ rad52Δ cells to the prototypic Sn1-type methylating agent N-methyl-N′-nitro-N-nitrosoguanidine. We also report evidence that in human MGMT-deficient cell-free extracts, CAF-1-dependent packaging of irreparable O6-mG-T mispair-containing DNA into nucleosomes suppresses its degradation by the MMR system. Taken together, these findings suggest that CAF-1-dependent incorporation of irreparable O6-mG-T mispair-containing DNA into nucleosomes suppresses its degradation by the MMR system, thereby defending the cell against killing by the Sn1-type methylating agent.