Fluorescence recovery in the super-resolution regime reveals subcompartments of 53BP1 foci.

ABSTRACT: Double-strand break (DSB) repair protein 53BP1 (p53 binding protein-1) mediates long-range DNA end-joining and heterochromatin maintenance. We exploit lattice structured illumination microscopy (SIM) (dual iterative SIM [diSIM, also called SIM²]; ∼60 nm lateral resolution) alongside lattice light-sheet microscopy and fluorescence recovery after photobleaching (FRAP) and reveal differences in 53BP1 foci contour and composition. Compact 53BP1 foci remain stationary, while amorphous foci undergo dynamic shape changes. Using FRAP in the super-resolution (SR) regime (FRAP-SR), we show that amorphous 53BP1 foci recover 53BP1-EGFP signals rapidly exhibiting subcompartments, indicating differential protein mobilities and functions within a single foci. In contrast, compact foci recover

SUBMITTER: Wu C 

PROVIDER: S-EPMC12461648 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature