Fig 1: Pericentric heterochromatin decompaction and recruitment of UV damage repair proteins. (A) Decompaction of pericentric heterochromatin following UVC laser damage analyzed in NIH/3T3 cells expressing GFP-DDB2 (UV damage sensor). (B,C) Quantification of GFP-DDB2 intensity in damaged heterochromatin (B) and chromocenter area (C) relative to before damage. Data are presented as mean values ± SEM from 12–45 cells (depending on the timepoint) scored in at least eleven independent experiments. (D) Recruitment of XPB repair protein analyzed by immunofluorescence 1 h after UVC laser micro-irradiation in NIH/3T3 GFP-DDB2 cells. Antibodies used: primary antibody anti-XPB (Santa cruz Biotechnology sc-293, 1:400), secondary antibody anti-rabbit Alexa Fluor 594 (Invitrogen A11037, 1:1,1000). (E) Hoechst photoconversion control after UVC laser micro-irradiation in NIH/3T3 cells (parental cell line vs cells expressing GFP-DDB2) followed by immunofluorescence for UV lesions (Cyclobutane Pyrimidine Dimers, CPD) 30 min after irradiation. Antibodies used: primary antibody anti-CPD (Cosmo Bio CAC-NM-DND-001, clone TDM2, 1:1,000), secondary antibody anti-mouse Alexa Fluor 647 (Invitrogen A21236, 1:1,000). Imaging settings were kept the same for both cell types. The arrowheads point to damaged chromocenters. All microscopy images are confocal sections. Scale bars, 10 µm. Data from Fortuny et al. (2021).