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The Transcriptional Co-Repressor C-Terminal Binding Protein (CtBP) Associates with Centrosomes During Mitosis
Moira Spyer and Martin J. Allday
volume 5 | issue 5
1 march 2006Pages: 530 - 537
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CtBP is a co-repressor of transcription that acts by inhibiting co-activators and recruiting to promoter control elements (via interactions with DNA-binding transcription factors) a complex of proteins that modify histones, repress transcription and silence gene expression. There are two highly homologous genes, CtBP1 and CtBP2 that encode CtBP. In addition, a CtBP1-related protein has been described that has 11 fewer amino acids at its N-terminus than CtBP1. This variant of CtBP1 – known as CtBP3 or BARS [Brefeldin A (BFA) ribosylated substrate] – plays a critical role in the fragmentation of the Golgi complex at the onset of mitosis. Although there are some reports of CtBP with a cytoplasmic distribution after transfection, it is unclear how in normal cells a nuclear co-repressor regulates the behaviour of the Golgi complex at the onset of mitosis. Using polyclonal rabbit antibodies that were raised against a human CtBP1-GST fusion-protein, here we show by immunofluorescence laser-scanning confocal microscopy that in mitotic cells a species of CtBP becomes associated with the centrosomes at the onset of prophase and then throughout mitosis. The association can be seen in both cycling mitotic cells and nocodazole-arrested cells. The interaction was confirmed by co-immunoprecipitation and centrosome isolation. Since centrosomes are considered to be the organising centre for Golgi morphogenesis, the interaction demonstrated here may explain how a nuclear co-repressor of transcription can exert a regulatory effect on the Golgi complex at a specific stage of the cell cycle.
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDF If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.