Delayed secondary glucocorticoid response elements. Unusual nucleotide motifs specify glucocorticoid receptor binding to transcribed regions of alpha 2u-globulin DNA
Glucocorticoids stimulate the transcription of rat alpha 2u-globulin (RUG) genes. Because this induction occurs after a time lag of several hours and is blocked by inhibitors of protein synthesis, it exemplifies a delayed secondary response to steroid hormones. In this report, we show that a region...
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Veröffentlicht in: | The Journal of biological chemistry 1991-11, Vol.266 (33), p.22634-22644 |
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Zusammenfassung: | Glucocorticoids stimulate the transcription of rat alpha 2u-globulin (RUG) genes. Because this induction occurs after a time
lag of several hours and is blocked by inhibitors of protein synthesis, it exemplifies a delayed secondary response to steroid
hormones. In this report, we show that a region of RUG-transcribed DNA (approximately +1800 to +2174) contains multiple footprint
sites for glucocorticoid receptor that are, apparently, organized into at least three independent binding clusters. The DNA
sequences bound by the receptor and the location of binding sites were determined. A family of sequences related to half-sites
of the consensus primary glucocorticoid response element (GRE) is discernible at each cluster of sites. Compared to the consensus
GRE, which contains two pseudo-palindromic hexanucleotides arranged in a tail-to-tail fashion and separated by three bases,
the arrangements of hexanucleotides within this segment of RUG DNA are unusual and heterogeneous. Methylation interference
of a binding cluster containing three receptor footprints demonstrates that certain guanines of the GRE-like hexanucleotides
are essential for efficient receptor binding. A synthetic 29-base pair (bp) RUG element, containing one receptor footprint
from this cluster, selectively binds the receptor. Within this 29-bp element, six nucleotides separate two directly repeated
copies of GRE-like hexanucleotides. RUG DNA fragments containing all or part of the three binding clusters, including the
29-bp element, confer a delayed secondary hormone responsiveness upon a linked heterologous promoter and reporter gene in
stably transfected cell lines. We speculate that the unusual DNA sequence motifs of the receptor-binding sites are crucial
for the generation of certain delayed secondary responses. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)54618-4 |