The “click chemistry” approach utilizing 5-ethynyl-2′-deoxyuridine (EdU) as a DNA precursor, recently introduced to detect DNA replication, offers several advantages over the classical BrdU methodology. However, in this issue Zhao and coworkers present evidence that EdU when incorporated into DNA of A549, TK6 or WTK1 cells during short pulse leads to severe problems, particularly exacerbated during the second round of replication. This is discernible by DNA damage signaling reported by phosphorylation of ATM on Ser1981, histone H2AX on Ser139, p53 on Ser15 and Chk2 on Thr68. The data indicate that DNA replication using a template containing incorporated EdU is protracted and results in DNA damage, including formation of DNA double strand breaks. Progression of EdU labeled cells through the cell cycle, mainly through G2, is perturbed likely in response to activation of Chk2. Subsequently the cells undergo apoptosis. Severity of the effects varies in cells having different status (wt versus mutated) of p53.
DNA damage signaling, impairment of cell cycle progression, and apoptosis triggered by 5-ethynyl-2′-deoxyuridine incorporated into DNA
Hong Zhao, H. Dorota Halicka, Jiangwei Li, Ewa Biela, Krzysztof Berniak, Jurek Dobrucki and Zbigniew Darzynkiewicz
Commentary related to the above article:
Prospects and limitations of “Click-Chemistry”-based DNA labeling technique employing 5-ethynyl-2′deoxyuridine (EdU) (pages 977–978)
Artur Cieślar-Pobuda and Marek J. Łos
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