Online imaging of initial DNA damages at the PTB microbeam.

In an inter-disciplinary collaboration of Physikalisch-Technische Bundesanstalt (PTB), German Collection of Microorganisms and Cell Cultures (DSMZ) and Heinrich-Heine University, live-cell imaging has been established at the charged-particle microbeam facility of PTB. Candidate genes participating in DNA strand-break repair pathways such as PARP-1, MRE11, MSH2, MDC1 and p53BP1 have been modified to generate fluorescent fusion proteins. Using multi-cistronic expression vectors, stable genomic integration was achieved in HT-1080 fibroblasts. The aim of this study is to characterise and use these highly reliable cell lines for studying initial steps of DNA damage responses and kinetics of repair after microbeam irradiation with high- and low-linear energy transfer (LET) particles in living cells at physiological conditions.