| Literature DB >> 15558034 |
Vlada V Philimonenko1, Jian Zhao, Sebastian Iben, Hana Dingová, Katarína Kyselá, Michal Kahle, Hanswalter Zentgraf, Wilma A Hofmann, Primal de Lanerolle, Pavel Hozák, Ingrid Grummt.
Abstract
The presence of actin and nuclear myosin I (NMI) in the nucleus suggests a role for these motor proteins in nuclear functions. We have investigated the role of actin and nuclear myosin I (NMI) in the transcription of ribosomal RNA genes (rDNA). Both proteins are associated with rDNA and are required for RNA polymerase I (Pol I) transcription. Microinjection of antibodies against actin or NMI, as well as short interfering RNA-mediated depletion of NMI, decreased Pol I transcription in vivo, whereas overexpression of NMI augmented pre-rRNA synthesis. In vitro, recombinant NMI activated Pol I transcription, and antibodies to NMI or actin inhibited Pol I transcription both on naked DNA and pre-assembled chromatin templates. Whereas actin associated with Pol I, NMI bound to Pol I through the transcription-initiation factor TIF-IA. The association with Pol I requires phosphorylation of TIF-IA at Ser 649 by RSK kinase, indicating a role for NMI in the growth-dependent regulation of rRNA synthesis.Entities:
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Year: 2004 PMID： 15558034 DOI： 10.1038/ncb1190
Source DB: PubMed Journal: Nat Cell Biol ISSN： 1465-7392 Impact factor: 28.824