(a) Representative immunoblots showing the level of SUV39H1 in HEK293 cells expressing ectopic lamin A or progerin. (b) Quantification of experiments in burberry a. Data represent mean n two tailed burberry t test. (c) Representative western blotting showing the level of Suv39h1 in wild type and Zmpste24 MEFs and in kidney from wild type and Zmpste24 mice. (d) Quantification of experiments in c. Data represent mean n two tailed t test. (e) Representative immunoblots showing levels of different histone modifications in total cell lysate from burberry wild type and Zmpste24 MEFs and indicated wild type and Zmpste24 (f) Quantification of experiments in e. Data represent mean n two tailed t test. (g) Representative photos of immunofluorescence staining of H3K9me3 burberry in wild type and Zmpste24 MEFs. To investigate whether H3K9me3 is affected in Zmpste24 MEFs, burberry level of H3K9me3 was examined and compared between Zmpste24 MEFs and wild type littermates. As shown in Fig. 2e, the level of H3K9me3 was significantly increased in Zmpste24 MEFs and tissues (kidney and lung) compared with that in littermate wild type controls. In addition, the level of H4K20me3 was also significantly elevated in Zmpste24 MEFs compared with wild type controls, whereas H3K27me3 and H3K9me2 were hardly affected (Fig. 2e). The elevated H3K9me3 in Zmpste24 MEFs was further confirmed by immunofluorescence microscopy (Fig. 2g). The increase in levels of H3K9me3 and H4K20me3 in Zmpste24 MEFs was most likely attributable to unprocessed prelamin A, as ectopic unprocessible prelamin A (hereafter, prelamin A) led to similar upregulation in HEK293 cells (Fig. 3). Therefore, the accumulation of prelamin A and progerin results in increased H3K9me3.