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Transcriptional Coactivator PC4, a Chromatin-associated Protein, induces Chromatin Condensation

Das, Chandrima and Hizume, Kohji and Batta, Kiran and Kumar, Prashanth BR and Gadad, Shrikanth S and Ganguly, Semanti and Lorain, Stephanie and Verreault, Alain and Sadhale, Parag P and Takeyasu, Kunio and Kundu, Tapas K (2006) Transcriptional Coactivator PC4, a Chromatin-associated Protein, induces Chromatin Condensation. In: Molecular and Cell Biology, 26 (22). pp. 1-63.

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Abstract

Human transcriptional coactivator PC4 is a highly abundant multifunctional protein, which plays diverse important roles in cellular processes including transcription, replication and repair. It is also a unique activator of p53 function. Here we report that PC4 is a bonafide component of chromatin with distinct chromatin organization ability. PC4 is predominantly associated with the chromatin throughout the stages of cell cycle and is broadly distributed on the mitotic chromosome arms in a punctate manner except the centromere. It selectively interacts with core histones H3 and H2B, which is essential for PC4-mediated chromatin condensation as demonstrated by micrococcal nuclease (MNase) accessibility assays, circular dichroism spectroscopy and atomic force microscopy (AFM). The AFM images show that PC4 compacts the 100 kb reconstituted chromatin distinctly as compared to the linker histone H1. Silencing of PC4 expression in HeLa cells results in chromatin decompaction as evidenced by the increase in MNase accessibility. Knocking down of PC4 up-regulates several genes leading to the $G_2/M$ check point arrest of cell cycle, which suggests the physiological role of it as a chromatin compacting protein. These results establish PC4 as a new member of chromatin associated protein (CAP) family, which plays an important role in chromatin organization.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to American Society for Microbiology.
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 19 Feb 2008
Last Modified: 19 Sep 2010 04:42
URI: http://eprints.iisc.ernet.in/id/eprint/12889

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