First published online September 9, 2005
Journal of Cell Science 118, 1804e (2005)
© The Company of Biologists Limited
RBP3 muscles in on Pol II
Transcription by RNA polymerase II (Pol II) is dynamically regulated by assembly of the core enzyme with mediator proteins, transcription factors and other auxiliary factors. Several core subunits are involved in tissue-specific transcription, including RPB3, which directly contacts the myogenic transcription factor myogenin and the transcription factor ATF4. Expression of RBP3 is tightly regulated during muscle differentiation. Now Claudio Passananti and colleagues report that its subcellular localization is also regulated during this process (see p. 4253). The authors show that RPB3 accumulates in the cytoplasm of cycling myogenic cells but migrates to the nucleus upon induction of differentiation. They then use two-hybrid analysis, together with coimmunoprecipitation and colocalization experiments in myogenic cells, to identify HCR (a gene product implicated in susceptibility to psoriasis) as the cytoplasmic RPB3-interacting protein. Finally, the authors demonstrate that knocking down HCR by RNAi in cycling myogenic cells results in migration of RBP3 to the nucleus. They therefore conclude that HCR provides a cytoplasmic docking site for RPB3 and suggest that this interaction represents an additional level of tissue-specific transcriptional regulation.
Related articles in JCS:
- RNA Polymerase II subunit 3 is retained in the cytoplasm by its interaction with HCR, the psoriasis vulgaris candidate gene product
- Nicoletta Corbi, Tiziana Bruno, Roberta De Angelis, Monica Di Padova, Valentina Libri, Maria Grazia Di Certo, Laura Spinardi, Aristide Floridi, Maurizio Fanciulli, and Claudio Passananti
JCS 2005 118: 4253-4260.
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