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- Title
Nuclear actin and myosin I are required for RNA polymerase I transcription.
- Authors
Philimonenko, Vlada V; Zhao, Jian; Iben, Sebastian; Dingová, Hana; Kyselá, Katarína; Kahle, Michal; Zentgraf, Hanswalter; Hofmann, Wilma A; de Lanerolle, Primal; Hozák, Pavel; Grummt, Ingrid
- 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.
- Publication
Nature cell biology, 2004, Vol 6, Issue 12, p1165
- ISSN
1465-7392
- Publication type
Journal Article
- DOI
10.1038/ncb1190