(A, B) Projection of an extended section of a HGPS nucleus showing lamin A (blue), LAP2α (red) and TRF1 (green) staining. Scale bar (A): 3 μm; scale bar (B): 2 μm. (C) Average surface occupied by LAP2α in wild type and HGPS nuclei (errors bars indicate SEM, p < 0.001, n = 25, Student's t-test). (D) Processed section of a wild-type nucleus showing LAP2α (pink), TRF1 (green) and lamin A. The yellow line marks the borders of the area used to quantify the average LAP2α surface coverage per nucleus (LAP2c = 15.3% in this nucleus). Scale bar: 3 μm. (E) Higher magnification of identified telomeres objects shown in (D). The red line marks the borders of the area used to quantify the LAP2α surface coverage for each telomere. LAP2α surface coverage for each telomere is indicated in brackets: telomere 1: 12.5% , telomere 2: 85% , telomere 3: 36% , telomere 4: 0% . (F) Proportion of the surface of a telomere associated with LAP2α in WT or TERT+HGPS nuclei. The LAP2α/TRF1 colocalization is expressed in relation to the average surface occupied by LAP2α for each nucleus (LAP2c: average nuclear surface covered by LAP2α in one nucleus, [n = 25, *p < 0.05, ***p < 0.001, errors bars indicate SEM, two-way ANOVA with Bonferroni's post-test]). (G) 3D rendering of a wild type nucleus from super resolution imaging data. The nuclear lamina (light blue) has been rendered partially to allow visualizing the position of telomeres within the nucleus. Telomeres are represented as spheres and their proximity to the nuclear lamina is indicated as follows: within 250 nm (red) or outside 250 nm (green) of the nuclear lamina. Scale bar: 2 μm. (H) Intensity profile of LAP2α (red) near telomeres (TRF1, green) in TERT+ human fibroblasts, control (left part) or progerin expressing nuclei (right part) along a ∼400 nm axis, relative to the minimum and maximum LAP2α and TRF1 signal per nucleus. Dotted lines indicate SEM, n ≥ 38 nuclei. (I) Average LAP2α intensity in control or progerin induced TERT+ human fibroblasts (n ≥ 38, **p < 0.01, errors bars indicate SEM, Student's t-test).