Actin and hnRNP U cooperate for productive transcription by RNA polymerase II.
To determine the role of actin-ribonucleoprotein complexes in transcription, we set out to identify novel actin-binding proteins associated with RNA polymerase II (Pol II). Using affinity chromatography on fractionated HeLa cells, we found that hnRNP U binds actin through a short amino acid sequence in its C-terminal domain. Post-transcriptional gene silencing of hnRNP U and nuclear microinjections of a short peptide encompassing the hnRNP U actin-binding sequence inhibited BrUTP incorporation in vivo. In living cells, we found that both actin and hnRNP U are associated with the phosphorylated C-terminal domain of Pol II, and antibodies to actin and hnRNP U blocked Pol II-mediated transcription. Taken together, our results indicate that a general actin-based mechanism is implicated in the transcription of most Pol II genes. Actin in complex with hnRNP U may carry out its regulatory role during the initial phases of transcription activation.
Kukalev
Alexander
A
Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, S-171 77, Stockholm, Sweden.
Nord
Ylva
Y
Palmberg
Carina
C
Bergman
Tomas
T
Percipalle
Piergiorgio
P
D000199:Actins / Q000378:metabolism / Q000502:physiology*; D000595:Amino Acid Sequence; D020868:Gene Silencing; D006367:HeLa Cells; D034722:Heterogeneous-Nuclear Ribonucleoprotein U / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
D000199:Actins; D034722:Heterogeneous-Nuclear Ribonucleoprotein U; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012319:RNA Polymerase II