title: SUV39h-independent association of HP1 beta with fibrillarin-positive nucleolar regions.
abstract: 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.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, CZ-612 65, Brno, Czech Republic.
authors.forename: Andrea Harnicarová
authors.initials: AH
authors.lastname: Horáková
authors.forename: Eva
authors.initials: E
authors.lastname: Bártová
authors.forename: Gabriela
authors.initials: G
authors.lastname: Galiová
authors.forename: Radka
authors.initials: R
authors.lastname: Uhlírová
authors.forename: Pavel
authors.initials: P
authors.lastname: Matula
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kozubek
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000378:metabolism*; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D008780:Methyltransferases / Q000378:metabolism*; D051379:Mice; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*
chemical_list: C096188:Cbx1 protein, mouse; D002868:Chromosomal Proteins, Non-Histone; D012097:Repressor Proteins; C047458:fibrillarin; C498700:Suv39h1 protein, mouse; D008780:Methyltransferases