646 Histochem Cell Biol (2012) 138:643–651 Fig. 1 Prelamin A accumulation in low or high passage MADA cells. Immunoﬂuorescence analysis of control or MADA ﬁbroblasts at passage 8 (a) and at passage 25 (b) Lamin A/C was labelled by polyclonal anti-lamin A/C. Prelamin A was labelled by 1188-1, 1188-2 or Sc-6214 antibody, as indicated. Bar 10 lm. c Schematic representation of prelamin A epitopes that have been employed to mevinolin in combination or not with TSA to cell cultures have been previously shown to rescue the chromatin phenotype in progeria cells (Columbaro et al. 2005; Galiova et al. 2008). In order to deﬁne the efﬁcacy of these pharmaceutical tools in MADA cells, we considered the labelling pattern of tri-H3K9 as a parameter, and monitored its staining before and after drug treatment. Administration of mevinolin rescued the labelling pattern of tri-H3K9 in low passage MADA ﬁbroblasts, while treatment was not effective in high passage cells (Fig. 2a, middle and bottom row, respectively). In fact, in mevin- olin-treated MADA cells at passage 8, the diffuse staining characteristic of untreated MADA nuclei at any passage number was changed to intranuclear clusters, comparable to the pattern observed in control nuclei. However, the diffuse tri-H3K9 staining of MADA ﬁbroblasts at passage 25 was not improved by the drug (Fig. 2a, bottom row). The different responsiveness of the three MADA cell cultures to drug treatments is shown in Fig. 2b and c. As 123 raise the antibodies used in the present study. Speciﬁc sequences are indicated; F stands for farnesyl group. d Western blot analysis of control, mevinolin-treated or MADA ﬁbroblasts. Prelamin A was labelled by Sc-6214 or 1188-1 antibody. Representative pictures of at least three experiments are shown shown by the statistical analysis, the age of patient at biopsy, but not the mutation, inﬂuenced drug efﬁcacy. TSA administration, following mevinolin treatment, induced an even more pronounced improvement, indicat- ing a positive synergistic effect on the rescue of chromatin organisation (Fig. 2c). Drug treatment rescues SUN2 organization in MADA cells SUN1 and SUN2 are nuclear membrane proteins known to interact with prelamin A (Crisp et al. 2006; Mattioli et al. 2011). Immunoﬂuorescence assays in MADA ﬁbroblasts revealed altered distribution of both proteins. In fact, SUN1 was properly localized at the nuclear envelope, but it was also found at intranuclear invaginations. Prelamin A aggregates were found to colocalize with SUN1-labeled nuclear invaginations. Further, SUN2 was mislocalized forming a honey-comb-like lattice in the nuclear membrane