Double-strand breaks (DSB) in DNA are among the most dangerous types of DNA damageoccuring within cells. One of the earliest cellular responses to double-strand breaks is the phosphorylation of a histone variant, H2AX, at the sites of DNA damage. Within seconds Ser139 is phosphorylated when DSBs are induced in mammalian cells. Phosphorylation of this serine residue causes chromatin condensation and appears to play a critical role in the recruitment of repair or damage-signaling factors to the DNA damage sites.
The OxiSelect™ DNA Double-Strand Break Staining Kit provides an easy-to-use method for detecting the presence of DSBs in cells cultured in microtiter plates. Double strand breaks can be detected in just a few hours by immunofluorescence staining of the phosphorylatedhistoneH2AX.
Figure 1: DNA Double-Strand Break Formation in A549 Cells. A549 cells were seeded at 50,000 cells/well overnight. (A) Untreated cells. (B) Cells treated with 100 µM Etoposide for 1 hour. Immunofluorescence staining was then performed according to the Assay Protocol.