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Molecular and Cellular Biology, March 2000, p. 2031-2042, Vol. 20, No. 6
Department of Molecular and Cellular Biology,
Baylor College of Medicine, Houston, Texas 77030
Received 22 October 1999/Returned for modification 4 December
1999/Accepted 14 December 1999
We have characterized the mechanism by which coactivator p300
facilitates transcriptional activation mediated by the heterodimer of
thyroid hormone (T3) receptor and 9-cis retinoid acid
receptor (TR-RXR) in the context of chromatin. We demonstrate that,
while p300 can enhance the transcriptional activation mediated by both liganded TR-RXR and GAL4-VP16, its histone acetyltransferase activity (HAT) is required for its ability to facilitate liganded TR-RXR- but
not GAL4-VP16-mediated transcriptional activation. To understand how
p300 is recruited by liganded TR-RXR, we have analyzed the interactions
between TR-RXR and p300 as well as SRC-1 family coactivators. We show
that, in contrast to a strong hormone-dependent interaction between
TR-RXR and SRC-1 family coactivators, p300 displays minimal, if any,
T3-dependent interaction with TR-RXR. However, p300 can be recruited by
liganded TR-RXR through its interaction with SRC-1 family coactivators.
Consistent with the protein-protein interaction profile described
above, we demonstrate that the SRC-1 interaction domain of p300 is
important for its ability to facilitate transcriptional activation
mediated by TR-RXR, whereas its nuclear receptor interaction domain is
dispensable. Collectively, these results reveal the functional
significance of the HAT activity of p300 and define an indirect mode
for the action of p300 in TR-RXR activation.
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
p300 Requires Its Histone Acetyltransferase
Activity and SRC-1 Interaction Domain To Facilitate Thyroid Hormone
Receptor Activation in Chromatin
*
Corresponding author. Mailing address: Department of
Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030. Phone: (713) 798-6291. Fax: (713) 790-1275. E-mail: jwong{at}bcm.tmc.edu.
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