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Updated: Jun 5, 2026

Visualization of DNA Repair Proteins Interaction by Immunofluorescence
Published on: June 26, 2020
H2AX phosphorylation in response to DNA double-strand break formation during bystander signalling: effect of microRNA
Jennifer S Dickey1, Franz J Zemp, Alvin Altamirano
1Laboratory of Molecular Pharmacology, Center for Cancer Research, NCI, NIH, 9000 Rockville Pike, Bethesda, MD 20892, USA.
Abstract:
Upon DNA double-strand break (DSB) formation, hundreds of H2AX molecules in the chromatin flanking the break site are phosphorylated on serine residue 139, termed gamma-H2AX, so that virtually every DSB site in a nucleus can be visualised within 10 min of its formation using an antibody to gamma-H2AX. One application of this sensitive assay is to examine the induction of DNA double-strand damage in subtle non-targeted cellular effects such as the bystander effect. Here whether microRNA (miRNA) serve as a primary signalling mechanism for bystander effect propagation by comparing matched human colon carcinoma cell lines with wild-type or depleted levels of mature miRNAs was investigated. No major differences were found in the levels of induced gamma-H2AX foci in the tested cell lines, indicating that though miRNAs play a role in bystander effect manifestation, they appear not to be the primary bystander signalling molecules in the formation of bystander effect-induced DSBs.
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