Nuclear actin and myosin I are required for RNA polymerase I transcription

作者：Philimonenko VV; Zhao J; Iben S; Dingova H; Kysela K; Kahle M; Zentgraf H; Hofmann WA; de Lanerolle P; Hozak P; Grummt I^*

来源：Nature Cell Biology, 2004, 6(12): 1165-1172.

DOI：10.1038/ncb1190

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.

• 出版日期2004-12