Horáková Andrea Harnicarová, Bártová Eva, Galiová Gabriela, Uhlírová Radka, Matula Pavel, Kozubek Stanislav
Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, CZ-612 65, Brno, Czech Republic.
Chromosoma. 2010 Jun;119(3):227-41. doi: 10.1007/s00412-009-0252-2. Epub 2009 Dec 23.
Heterochromatin protein 1 (HP1), which binds to sites of histone H3 lysine 9 (H3K9) methylation, is primarily responsible for gene silencing and the formation of heterochromatin. We observed that HP1 beta is located in both the chromocenters and fibrillarin-positive nucleoli interiors. However, HP1 alpha and HP1 gamma occupied fibrillarin-positive compartments to a lesser extent, corresponding to the distinct levels of HP1 subtypes at the promoter of rDNA genes. Deficiency of histone methyltransferases SUV39h and/or inhibition of histone deacetylases (HDACi) decreased HP1 beta and H3K9 trimethylation at chromocenters, but not in fibrillarin-positive regions that co-localized with RNA polymerase I. Similarly, SUV39h- and HDACi-dependent nucleolar rearrangement and inhibition of rDNA transcription did not affect the association between HP1 beta and fibrillarin. Moreover, the presence of HP1 beta in nucleoli is likely connected with transcription of ribosomal genes and with the role of fibrillarin in nucleolar processes.
异染色质蛋白1（HP1）与组蛋白H3赖氨酸9（H3K9）甲基化位点结合，主要负责基因沉默和异染色质的形成。我们观察到，HP1β定位于异染色质中心和原纤维蛋白阳性的核仁内部。然而，HP1α和HP1γ在较小程度上占据原纤维蛋白阳性区室，这与rDNA基因启动子处不同水平的HP1亚型相对应。组蛋白甲基转移酶SUV39h的缺失和/或组蛋白去乙酰化酶的抑制（HDACi）降低了异染色质中心处的HP1β和H3K9三甲基化，但在与RNA聚合酶I共定位的原纤维蛋白阳性区域中没有降低。同样，SUV39h和HDACi依赖的核仁重排以及rDNA转录的抑制并不影响HP1β与原纤维蛋白之间的关联。此外，HP1β在核仁中的存在可能与核糖体基因的转录以及原纤维蛋白在核仁过程中的作用有关。
