Abstract
Human DNA polymerase iota (poliota) is a unique member of the Y-family of specialised polymerases that displays a 5'deoxyribose phosphate (dRP) lyase activity. Although poliota is well conserved in higher eukaryotes, its role in mammalian cells remains unclear. To investigate the biological importance of poliota in human cells, we generated fibroblasts stably downregulating poliota (MRC5-pol iota(KD)) and examined their response to several types of DNA-damaging agents. We show that cell lines downregulating poliota exhibit hypersensitivity to DNA damage induced by hydrogen peroxide (H(2)O(2)) or menadione but not to ethylmethane sulphonate (EMS), UVC or UVA. Interestingly, extracts from cells downregulating poliota show reduced base excision repair (BER) activity. In addition, poliota binds to chromatin after treatment of cells with H(2)O(2) and interacts with the BER factor XRCC1. Finally, green fluorescent protein-tagged poliota accumulates at the sites of oxidative DNA damage in living cells. This recruitment is partially mediated by its dRP lyase domain and ubiquitin-binding domains. These data reveal a novel role of human poliota in protecting cells from oxidative damage.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Alkylating Agents / pharmacology
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Cell Death / drug effects
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Cell Death / radiation effects
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Cell Extracts
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Cell Line
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Chromatin / enzymology
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Cytoprotection* / drug effects
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Cytoprotection* / radiation effects
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DNA Damage
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DNA Polymerase beta / metabolism
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DNA Polymerase iota
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DNA Repair / drug effects
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DNA Repair / radiation effects
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DNA-Binding Proteins / metabolism
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DNA-Directed DNA Polymerase / chemistry
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DNA-Directed DNA Polymerase / deficiency
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DNA-Directed DNA Polymerase / metabolism*
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Down-Regulation / drug effects
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Down-Regulation / radiation effects
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Fibroblasts / cytology*
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Fibroblasts / drug effects
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Fibroblasts / enzymology*
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Fibroblasts / radiation effects
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G1 Phase / drug effects
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G1 Phase / radiation effects
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Humans
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Hydrogen Peroxide / pharmacology
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Oxidative Stress* / drug effects
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Oxidative Stress* / radiation effects
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Protein Binding / drug effects
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Protein Binding / radiation effects
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Protein Structure, Tertiary
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Ultraviolet Rays
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Uracil / metabolism
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X-ray Repair Cross Complementing Protein 1
Substances
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Alkylating Agents
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Cell Extracts
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Chromatin
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DNA-Binding Proteins
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X-ray Repair Cross Complementing Protein 1
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XRCC1 protein, human
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Uracil
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Hydrogen Peroxide
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DNA Polymerase beta
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DNA-Directed DNA Polymerase
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DNA Polymerase iota
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POLI protein, human