The BRCA1 Breast Cancer Suppressor: Regulation of Transport, Dynamics, and Function at Multiple Subcellular Locations
Figure 4
Dynamic exchange of BRCA1 at nuclear foci determined by photobleaching assays. Several teams have studied the kinetics of recovery of DNA repair factors at DNA breaks by fluorescence recovery after photobleaching (FRAP) assay, although in the case of BRCA1-A complex proteins this was most often at laser-induced microirradiation lines that span the entire nucleus [77]. (a) A recent study used stable inducible cell lines to quantify and compare the dynamics of BRCA1 and associated DNA repair proteins at individual IR-induced foci in the nucleus [76]. This revealed a rapid recovery of different components, including BRCA1 and BARD1 which moved to and from foci as a dimer, and an extremely rapid on-off rate of the upstream factor RAP80. This is illustrated by rapid recovery of YFP-RAP80 at an individual focus (red arrow) following laser bleaching of the focal fluorescence (see also recovery curve graph). (b) The findings of that work are consistent with a hierarchy of protein targeting to foci (see left panel), but present a new perspective in terms of the dynamic nature of components at repair foci (see right panel). This figure was adapted from [76].
