648 Histochem Cell Biol (2012) 138:643–651 Fig. 3 SUN2 organization at the nuclear envelope is rescued by drug treatment. Control and patient ﬁbroblasts were cultured in the presence or absence of mevinolin (25 lM for 18 h). Cells were ﬁxed in ice cold methanol and immunoﬂuorescence assay was performed using goat anti-prelamin A and rabbit SUN1 or SUN2 antibodies. Cell nuclei were counterstained with DAPI. Panels a and b show SUN1 and SUN2 staining, respectively, in control and treated conditions as indicated (NT non-treated, MEV ? TSA treated with mevinolin and trichostatin A). c The graph represents the percentage of nuclei showing SUN2 in a honeycomb-like pattern in both control and (Columbaro et al. 2005, 2010; Filesi et al. 2005; Shumaker et al. 2006). Moreover, it has been shown that a direct correlation exists between levels of farnesylated prelamin A in the nuclear lamina and degree of H3K9 methylation (Columbaro et al. 2005, 2010; Lattanzi et al. 2007; Mattioli et al. 2008; Shumaker et al. 2006). Most importantly, it has been demonstrated that reduction of prelamin A levels or 123 MADA ﬁbroblasts, before and after treatment with mevinolin (25 lM for 18 h) and mevinolin (25 lM for 18 h) followed by trichostatin A (2.5 lM for 24 h) (NT, MEV and MEV ? TSA, respectively). Nuclei were considered positive to SUN2 alteration when displaying a honeycomb pattern on the nuclear surface. Experiments were performed 3 times and a minimum of 200 nuclei was counted per sample. Values are means of three independent experiments ± stan- dard deviation; p values indicate the statistical signiﬁcance of the difference of treated MADA samples compared with the untreated one impairment of its farnesylation in laminopathic cells improves tri-H3K9 labelling pattern within the nucleus, thus supporting the intriguing hypothesis that some enzymatic activity regulating histone 3 methylation may be affected by prelamin A accumulation (Columbaro et al. 2005). Here, we demonstrate that rescue of tri-H3K9 methyl- ation can be achieved in MADA ﬁbroblasts at low passage