Mattioli Elisabetta, Columbaro Marta, Capanni Cristina, Santi Spartaco, Maraldi Nadir M, D'Apice M Rosaria, Novelli Giuseppe, Riccio Massimo, Squarzoni Stefano, Foisner Roland, Lattanzi Giovanna
IGM-CNR, Unit of Bologna, c/o IOR, Via di Barbiano 1/10 I-40136 Bologna, Italy.
Exp Cell Res. 2008 Feb 1;314(3):453-62. doi: 10.1016/j.yexcr.2007.11.012. Epub 2007 Nov 24.
Increasing interest in drugs acting on prelamin A has derived from the finding of prelamin A involvement in severe laminopathies. Amelioration of the nuclear morphology by inhibitors of prelamin A farnesylation has been widely reported in progeroid laminopathies. We investigated the effects on chromatin organization of two drugs inhibiting prelamin A processing by an ultrastructural and biochemical approach. The farnesyltransferase inhibitor FTI-277 and the non-peptidomimetic drug N-acetyl-S-farnesyl-l-cysteine methylester (AFCMe) were administered to cultured control human fibroblasts for 6 or 18 h. FTI-277 interferes with protein farnesylation causing accumulation of non-farnesylated prelamin A, while AFCMe impairs the last cleavage of the lamin A precursor and is expected to accumulate farnesylated prelamin A. FTI-277 caused redistribution of heterochromatin domains at the nuclear interior, while AFCMe caused loss of heterochromatin domains, increase of nuclear size and nuclear lamina thickening. At the biochemical level, heterochromatin-associated proteins and LAP2 alpha were clustered at the nuclear interior following FTI-277 treatment, while they were unevenly distributed or absent in AFCMe-treated nuclei. The reported effects show that chromatin is an immediate target of FTI-277 and AFCMe and that dramatic remodeling of chromatin domains occurs following treatment with the drugs. These effects appear to depend, at least in part, on the accumulation of prelamin A forms, since impairment of prelamin A accumulation, here obtained by 5-azadeoxycytidine treatment, abolishes the chromatin effects. These results may be used to evaluate downstream effects of FTIs or other prelamin A inhibitors potentially useful for the therapy of laminopathies.
对作用于前体核纤层蛋白A的药物的兴趣日益增加，源于前体核纤层蛋白A参与严重核纤层蛋白病的发现。在前体核纤层蛋白A法尼基化抑制剂改善早衰样核纤层蛋白病的核形态方面，已有广泛报道。我们采用超微结构和生化方法，研究了两种抑制前体核纤层蛋白A加工的药物对染色质组织的影响。将法尼基转移酶抑制剂FTI-277和非肽模拟药物N-乙酰-S-法尼基-L-半胱氨酸甲酯（AFCMe）给予培养的对照人成纤维细胞6或18小时。FTI-277干扰蛋白质法尼基化，导致未法尼基化的前体核纤层蛋白A积累，而AFCMe损害核纤层蛋白A前体的最后切割，预计会积累法尼基化的前体核纤层蛋白A。FTI-277导致异染色质结构域在核内重新分布，而AFCMe导致异染色质结构域丢失、核大小增加和核纤层增厚。在生化水平上，FTI-277处理后，异染色质相关蛋白和LAP2α聚集在核内，而在AFCMe处理的细胞核中，它们分布不均或缺失。所报道的效应表明，染色质是FTI-277和AFCMe的直接靶点，并且在用这些药物处理后，染色质结构域会发生显著重塑。这些效应似乎至少部分取决于前体核纤层蛋白A形式的积累，因为通过5-氮杂脱氧胞苷处理抑制前体核纤层蛋白A的积累，会消除染色质效应。这些结果可用于评估法尼基转移酶抑制剂或其他潜在用于治疗核纤层蛋白病的前体核纤层蛋白A抑制剂的下游效应。
