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Molecular and Cellular Biology, June 1999, p. 4255-4261, Vol. 19, No. 6
Institute of Biomedical and Life Sciences,
Division of Biochemistry and Molecular Biology, University of
Glasgow, Glasgow G12 8QQ, United Kingdom
Received 21 December 1998/Returned for modification 28 January
1999/Accepted 22 March 1999
RNA polymerase III (Pol III) transcription is subject to repression
by the retinoblastoma protein RB, both in vitro and in vivo (R. J. White, D. Trouche, K. Martin, S. P. Jackson, and T. Kouzarides,
Nature 382:88-90, 1996). This is achieved through a direct interaction
between RB and TFIIIB, a multisubunit factor that is required for the
expression of all Pol III templates (C. G. C. Larminie,
C. A. Cairns, R. Mital, K. Martin, T. Kouzarides, S. P. Jackson, and R. J. White, EMBO J. 16:2061-2071, 1997; W.-M. Chu,
Z. Wang, R. G. Roeder, and C. W. Schmid, J. Biol. Chem.
272:14755-14761, 1997). p107 and p130 are two closely related proteins
that display 30 to 35% identity with the RB polypeptide and share some
of its functions. We show that p107 and p130 can both repress Pol III transcription in transient transfection assays or when added to cell
extracts. Pull-down assays and immunoprecipitations using recombinant
components demonstrate that a subunit of TFIIIB interacts physically
with p107 and p130. In addition, endogenous TFIIIB is shown by
cofractionation and coimmunoprecipitation to associate stably with both
p107 and p130. Disruption of this interaction in vivo by using the E7
oncoprotein of human papillomavirus results in a marked increase in Pol
III transcription. Pol III activity is also deregulated in fibroblasts
derived from p107 p130 double knockout mice. We conclude that TFIIIB is
targeted for repression not only by RB but also by its relatives p107
and p130.
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
RNA Polymerase III Transcription Factor IIIB Is a
Target for Repression by Pocket Proteins p107 and p130
*
Corresponding author. Mailing address: Institute of
Biomedical and Life Sciences, Division of Biochemistry and Molecular
Biology, Davidson Building, University of Glasgow, Glasgow G12 8QQ,
United Kingdom. Phone: 0141-330-4628. Fax: 0141-330-4620. E-mail:
rwhite{at}udcf.gla.ac.uk.
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