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The DNA damaging agents, MMS and As3+, increase ubiquitination of annexin I in nuclei of L5178Y tk(+/−) cells
Author(s) -
Hirata Aiko,
Hirata Fusao
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a912-b
Subject(s) - microbiology and biotechnology , annexin , dna damage , nuclear dna , chemistry , annexin a2 , biology , dna , cancer research , gene , biochemistry , mitochondrial dna , flow cytometry
DNA damaging agents such as methylmethanesulfonate (MMS) cause mutations of the thymidine kinase ( tk ) gene in L5178Y tk (+/−) lymphoma cells, thus causing resistance to trifluorothymidine. The mutation of the tk gene in L5178Y tk (+/−) cells by MMS can be reduced by the treatment with antisense oligonucleotides of annexin I or with inhibitors of annexin I helicase. Nuclear extracts of L5178Y tk (+/−) cells contain several species of annexin I with different molecular wights as determined by monospecific anti‐annexin I antibody. When L5178Y tk (+/−) cells were treated with MMS, higher molecular weights of annexin I increased, suggesting that nuclear annexin I is modified by DNA damage responding enzymes such as Rad 6. To confirm the modification of nuclear annexin I with ubiquitin or SUMO, L5178Y tk (+/−) cells were treated with MMS or As 3+ for 3 or 6 hrs, and then the immunoprecipitates of nuclear extracts with anti‐annexin I antibody were analyzed by Western blots with anti‐SUMO and anti‐ubiquitin antibodies. We found that nuclear annexin I is SUMOylated before the exposure, while annexin I is more ubiquitinated following the exposure. Our observations suggest that nuclear annexin I is a target of DNA damage responding enzymes and that nuclear annexin I helicase is involved in repair and tolerance of DNA damage. Supported in parts by grants from NIEHS, NIH (R01ES10814) and Susan G. Komen Breast Cancer Foundation (BCTR0402383)