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Localized DNA cleavage secondary to genotoxic exposure adjacent to an Alu inverted repeat
Author(s) -
Ho Bay,
Baker Pamela M.,
Singh Sheetal,
Shih ShyhJen,
Vaughan Andrew T.
Publication year - 2012
Publication title -
genes, chromosomes and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.754
H-Index - 119
eISSN - 1098-2264
pISSN - 1045-2257
DOI - 10.1002/gcc.21938
Subject(s) - microbiology and biotechnology , genome instability , dna , alu element , biology , hypersensitive site , cleavage (geology) , dna damage , chromatin , inverted repeat , genetics , deoxyribonuclease i , gene , genome , human genome , paleontology , fracture (geology) , base sequence
Radiation is a potent inducer of DNA damage leading to both random DNA loss and mutation. As part of a study focused on the mechanism whereby cells undergo loss of heterozygosity (LOH), a region of common LOH telomeric termination at 11q24 was observed in clones of H292 mucoepidermoid cells established after irradiation (IR). A 10‐kbp region including the telomeric extent of LOH termination was analyzed after IR using six sets of ligation‐mediated polymerase chain reaction (PCR) primers to detect the presence of DNA breaks. A cluster of DNA breaks was detected that closely mapped to the telomeric extent of LOH and which were observed up to 8 hr after IR. Repeating the experiment in the presence of the inhibitor of apoptosis, zVAD.fmk, did not change the location or amount of cleavage. A similar distribution of breaks was also seen in the MCF‐10A breast cancer cell line after IR. Further inspection of the involved region showed that 22/32 and 7/7 DNA breaks found in H292 and MCF‐10A cells, respectively, were located either in or immediately adjacent to an AluSx1 sequence, itself ∼1 kbp 5′ to an AluSq2 that was in an inverted orientation to the AluSx1. The region between the inverted Alu repeats was notable for both DNAse hypersensitivity and an open chromatin conformation inferred from histone modification data. These factors may contribute to genomic instability at this location. © 2012 Wiley Periodicals, Inc.