The alpha-like RNA polymerase II core subunit 3 (RPB3) is involved in tissue-specific transcription and muscle differentiation via interaction with the myogenic factor myogenin.
RNA polymerase II core subunit 3 (RPB3) is an a-like core subunit of RNA polymerase II (pol II). It is selectively down-regulated upon treatment with doxorubicin (dox). Due to the failure of skeletal muscle cells to differentiate when exposed to dox, we hypothesized that RPB3 is involved in muscle differentiation. To this end, we have isolated human muscle RPB3-interacting proteins by using yeast two-hybrid screening. It is of interest that an interaction between RPB3 and the myogenic transcription factor myogenin was identified. This interaction involves a specific region of RPB3 protein that is not homologous to the prokaryotic a subunit. Although RPB3 contacts the basic helix-loop-helix (HLH) region of myogenin, it does not bind other HLH myogenic factors such as MyoD, Myf5, and MRF4. Coimmunoprecipitation experiments indicate that myogenin contacts the pol II complex and that the RPB3 subunit is responsible for this interaction. We show that RPB3 expression is regulated during muscle differentiation. Exogenous expression of RPB3 slightly promotes myogenin transactivation activity and muscle differentiation, whereas the region of RPB3 that contacts myogenin, when used as a dominant negative molecule (Sud), counteracts these effects. These results indicate for the first time that the RPB3 pol II subunit is involved in the regulation of tissue-specific transcription.
Istituto di Tecnologie Biomediche, CNR, 00137 Rome, Italy.
Nicoletta
N
Corbi
Monica
M
Di Padova
Roberta
R
De Angelis
Tiziana
T
Bruno
Valentina
V
Libri
Simona
S
Iezzi
Aristide
A
Floridi
Maurizio
M
Fanciulli
Claudio
C
Passananti
D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D006801:Humans; D051379:Mice; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D018008:Myogenin / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
C503799:MYOG protein, human; C503801:Myog protein, mouse; D018008:Myogenin; D029701:Saccharomyces cerevisiae Proteins; C491783:POLR2C protein, human; D012319:RNA Polymerase II; C112110:RPB3 protein, S cerevisiae