Transcription-dependent rearrangements of actin and nuclear myosin I in the nucleolus

0351320 - ÚMG 2011 RIV DE eng J - Journal Article
Philimonenko, Vlada - Janáček, Jiří - Harata, M. - Hozák, Pavel
Transcription-dependent rearrangements of actin and nuclear myosin I in the nucleolus.
Histochemistry and Cell Biology. Roč. 134, č. 3 (2010), s. 243-249. ISSN 0948-6143. E-ISSN 1432-119X
R&D Projects: GA ČR(CZ) GA204/07/1592; GA MŠMT 2B06063; GA MŠMT LC545; GA MŠMT ME09101
Institutional research plan: CEZ:AV0Z50520514; CEZ:AV0Z50110509
Keywords : RNA-polymerase-I * ultrastructural analysis * UBF
Subject RIV: EB - Genetics ; Molecular Biology
Impact factor: 4.727, year: 2010

Nuclear actin and nuclear myosin I (NMI) are important players in transcription of ribosomal genes. Transcription of rDNA takes place in highly organized intranuclear compartment, the nucleolus. In this study, we characterized the localization of these two proteins within the nucleolus of HeLa cells with high structural resolution by means of electron microscopy and gold-immunolabeling. We demonstrate that both actin and NMI are localized in specific compartments within the nucleolus, and the distribution of NMI is transcription-dependent. Moreover, a pool of NMI is present in the foci containing nascent rRNA transcripts. Actin, in turn, is present both in transcriptionally active and inactive regions of the nucleolus and colocalizes with RNA polymerase I and UBF. Our data support the involvement of actin and NMI in rDNA transcription and point out to other functions of these proteins in the nucleolus, such as rRNA maturation and maintenance of nucleolar architecture.
Permanent Link: http://hdl.handle.net/11104/0191099