Figure 2.

Immunofluorescence labeling of methylated H3 histone species in control and HGPS fibroblasts. H3K9 labeling was performed by specific antibodies and revealed by FITC-conjugated secondary antibody (green); lamin A/C was labeled by polyclonal antibody and revealed by Cy-3-conjugated secondary antibody (red); DNA was counterstained with DAPI; mono- H3K9 labeling (A); di- H3K9 labeling (B); tri-H3K9 labeling (C). A representative experiment performed in HGADFN127 fibroblasts is shown in this picture. Quantitation of H3K9 staining shown in each panel is reported on the right. Bars show the mean percentage of nuclei with reduced fluorescence intensity. Nuclei with reduced fluorescence intensity were considered the nuclei with less than 50% of the mean fluorescence intensity measured in control nuclei (Lucia Image Version 4.61 software was used to measure fluorescence intensity per area). Mean values of triplicate counting performed in each patient cell line (see legend for details) including standard errors of the mean were calculated.