Live Cell Imaging System At IMP Microbeam Facility

Ion microbeam has become a powerful tool to investigate intracellular responses to ion irradiation. In order to study the dynamics of repair protein recruitment to DNA lesion site damaged by ion irradiation, a live cell imaging(LCI) system at the IMP heavy ion microbeam facility was established in this work. The early response of DNA single-strand-break repair protein XRCC1 to heavy ion irradiation was investigated, and the kinetics of recruitment and release was obtained by image analysis.The established LCI system consists of an Olympus IX81 microscope, home-made cell culture supporting system, and Micro-manager image acquisition package. The LCI system can support long time, sterile, cell culture at constant temperature at the microbeam beamline, and perform customized time-laps imaging with multi-channel and multi-position three-dimensional fluorescence microscopy, it also supports online cell irradiation with heavy ions of different energy. HT1080 cells expressing RFP-XRCC1 was irradiated with single Ni ions of 6.2Me V/u. The LCI observation showed that XRCC1 protein was recruited to the ion hit position within 20 seconds and formed bright foci in the cell nucleus. The fast recruitment of XRCC1 reached the maximum time in about 130 seconds, and then followed by a slower release, while the total XRCC1 protein remained constant in the nucleoplasm. Further image analysis showed that the recruitment and release of XRCC1 protein at the heavy ion hit position follows the exponential repair model of DNA single strand break.In summary, the work has set up an online live cell imaging system at IMP heavy ion microbeam facility and obtained the spatial-temporal repair kinetics of XRCC1 protein in the early time of DNA damage induced by heavy ion microbeam.