Mitotic repression of transcription in vitro.
J Cell Biol
; 120(3): 613-24, 1993 Feb.
Article
in En
| MEDLINE
| ID: mdl-8381119
ABSTRACT
A normal consequence of mitosis in eukaryotes is the repression of transcription. Using Xenopus egg extracts shifted to a mitotic state by the addition of purified cyclin, we have for the first time been able to reproduce a mitotic repression of transcription in vitro. Active RNA polymerase III transcription is observed in interphase extracts, but strongly repressed in extracts converted to mitosis. With the topoisomerase II inhibitor VM-26, we demonstrate that this mitotic repression of RNA polymerase III transcription does not require normal chromatin condensation. Similarly; in vitro mitotic repression of transcription does not require the presence of nucleosome structure or involve a general repressive chromatin-binding protein, as inhibition of chromatin formation with saturating amounts of non-specific DNA has no effect on repression. Instead, the mitotic repression of transcription appears to be due to phosphorylation of a component of the transcription machinery by a mitotic protein kinase, either cdc2 kinase and/or a kinase activated by it. Mitotic repression of RNA polymerase III transcription is observed both in complete mitotic cytosol and when a kinase-enriched mitotic fraction is added to a highly simplified 5S RNA transcription reaction. We present evidence that, upon depletion of cdc2 kinase, a secondary protein kinase activity remains and can mediate this in vitro mitotic repression of transcription.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Oocytes
/
Transcription, Genetic
/
Mitosis
Type of study:
Prognostic_studies
Limits:
Animals
Language:
En
Journal:
J Cell Biol
Year:
1993
Type:
Article