Thyroid Hormone Receptor Mediates Transcriptional Activation and Repression of Different Promoters in vitro
Name
05 Datta and Jameson _ Molecular Endocrinology.pdf
Description
RESEARCH PAPER
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1.75 MB
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Adobe PDF
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Author(s)
JAMESON, J. LARRY
MADISON, LAIRD
MAGGE, SHEILA
DATTA, SHOUMEN
Date Issued
1992
Publisher
The Endocrine Society
Abstract
The thyroid hormone receptor (TR) has the dual
ability to activate or repress transcription of specific
genes. A cell-free transcription system was used to
study the effects of TR on transcription by positively
(TREpMLP) and negatively (TSHa) regulated promoters.
Receptor-deficient HeLa cell extracts were
complemented with baculovirus-produced TR. TR
stimulated transcription from the TREpMLP promoter
by 3-fold, and trans-activation did not require
hormone. Transcriptional stimulation by TR required
the presence of the TRE sequence and was diminished
by the addition of competitor TRE binding
sites. Baculovirus-produced TR repressed transcription
in vitro from the TSHCI promoter by 30-50%,
also in a hormone-independent manner. Transcription
from a control adenovirus 2 major late promoter
was unaffected by added TR. Receptor-specific antisera
and competition with TRE binding sites impaired
TR-mediated repression of the TSHcv promoter.
Unlike transcriptional stimulation, which was
optimal when TR and HeLa extracts were added
concomitantly, transcriptional repression by the TR
was most effective when the receptor was preincubated
with the u-promoter, suggesting that receptor
binding to the promoter may block access of other
proteins to cause transcriptional repression. These
results indicate that baculovirus-expressed TR mediates
transcriptional activation and repression in a
promoter-specific manner in vitro. This system provides
a valuable model for examining transcriptional
control by the TR. (Molecular Endocrinology 6: 615
625,1992)
Description
RESEARCH PAPER
Subjects
Transcription, TRE, baculovirus system, receptors
MIT Department
Massachusetts Institute of Technology. Auto-ID Laboratory
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