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Induction of Persistent Double Strand Breaks Following Multiphoton Irradiation of Cycling and G 1 ‐arrested Mammalian Cells—Replication‐induced Double Strand Breaks
Author(s) -
Harper Jane V.,
Reynolds Pamela,
Leatherbarrow Emma L.,
Botchway Stanley W.,
Parker Anthony W.,
O’Neill Peter
Publication year - 2008
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2008.00378.x
Subject(s) - rad51 , dna repair , homologous recombination , dna damage , dna replication , cell cycle , dna , replication protein a , biology , microbiology and biotechnology , dna repair protein xrcc4 , colocalization , ku80 , cell , biophysics , nucleotide excision repair , dna binding protein , genetics , gene , transcription factor
DNA double strand breaks (DSBs) are amongst the most deleterious lesions induced within the cell following exposure to ionizing radiation. Mammalian cells repair these breaks predominantly via the nonhomologous end joining pathway which is active throughout the cell cycle and is error prone. The alternative pathway for repair of DSBs is homologous recombination (HR) which is error free and active during S‐ and G 2 /M‐phases of the cell cycle. We have utilized near‐infrared laser radiation to induce DNA damage in individual mammalian cells through multiphoton excitation processes to investigate the dynamics of single cell DNA damage processing. We have used immunofluorescent imaging of γ‐H2AX (a marker for DSBs) in mammalian cells and investigated the colocalization of this protein with ATM, p53 binding protein 1 and RAD51, an integral protein of the HR DNA repair pathway. We have observed persistent DSBs at later times postlaser irradiation which are indicative of DSBs arising at replication, presumably from UV photoproducts or clustered damage containing single strand breaks. Cell cycle studies have shown that in G 1 cells, a significant fraction of multiphoton laser‐induced prompt DSBs persists for >4 h in addition to those induced at replication.