Transformation of glucocorticoid receptors bound to the antagonist RU 486: effects of alkaline phosphatase

Gruol, Donald J.; Wolfe, Kristal A.

doi:10.1021/bi00486a026

Cited by 7 publications

(1 citation statement)

References 71 publications

(84 reference statements)

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“…To test this hypothesis, the ability of RU38486 to inhibit TPA induction of the collagenase promoter was determined. Although RU38486 is somewhat less efficient than dexamethasone or other agonists in promoting receptor activation (27,28,72), it can efficiently mediate in vitro activation and in vivo nuclear translocation of the GR (22,59,68). Indeed, in cells transfected with either the wild-type or mutant receptor, RU38486 efficiently induced nuclear translocation (data not shown).…”

Section: Vol 15 1995 Hormone-independent Gr-mediated Repression Ofmentioning

confidence: 99%

Hormone-Independent Repression of AP-1-Inducible Collagenase Promoter Activity by Glucocorticoid Receptors

Liu

Hillmann

Harmon

1995

Molecular and Cellular Biology

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The role of the ligand in glucocorticoid receptor-mediated transactivation and transrepression of gene expression was investigated. Half-maximal transactivation of a mouse mammary tumor virus-chloramphenicol acetyltransferase reporter gene in transfected cells expressing the human glucocorticoid receptor mutant GRL753F, from which the rate of ligand dissociation is four to five times higher than the rate of dissociation from normal receptors, required a 200-to 300-fold-higher concentration of dexamethasone than was required in cells expressing the normal receptor. Immunocytochemical analysis demonstrated that this difference was not the result of a failure of the mutant receptor to accumulate in the nucleus after steroid treatment. In contrast, in cells cotransfected with a reporter gene containing the AP-1-inducible collagenase gene promoter, the concentration of dexamethasone required for 50% transrepression was the same for mutant and normal receptors. Efficient receptor-mediated transrepression was also observed with the double mutant GRL753F/ C421Y, in which the first cysteine residue of the proximal zinc finger has been replaced by tyrosine, indicating that neither retention of the ligand nor direct binding of the receptor to DNA is required. RU38486 behaved as a full agonist with respect to transrepression. In addition, receptor-dependent transrepression, but not transactivation, was observed in transfected cells after heat shock in the absence of the ligand. Taken together, these results suggest that unlike transactivation, transrepression of AP-1 activity by the nuclear glucocorticoid receptor is ligand independent.The glucocorticoid receptor (GR) is a member of a family of ligand-dependent transcription factors capable of both positive and negative regulation of gene expression (4, 51, 69). In its unactivated form, the GR is part of a large heteromeric complex which includes hsp90 (18,35,45,61,67) and hsp56 (FKBP52) (42,57,61,63,81). Binding of the agonist stimulates receptor activation, dissociation from hsp90 (17, 66), and nuclear translocation, prerequisites for both transactivation and transrepression. For transactivation, specific in vitro binding of the activated GR to the glucocorticoid response element does not appear to be ligand dependent (22,79). However, in the absence of bound ligand, the nuclear form of the GR is a poor activator of target genes (52,65). This suggests that a ligandinduced conformational change, comparable to that inferred to be necessary for activation of the progesterone (2) and estrogen (5) receptors, is required for efficient activation (or derepression) of the transcriptional activating function present in the GR ligand-binding domain (34, 78) and/or for interaction of the receptor with other components of the transcription apparatus. Direct evidence for such a change has been provided by Simons et al., who demonstrated that affinity-labeled GR was less sensitive to proteolytic digestion than the unoccupied GR (74).Several mechanisms for GR-mediated transrepression ha...

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Section: Vol 15 1995 Hormone-independent Gr-mediated Repression Ofmentioning

confidence: 99%

Hormone-Independent Repression of AP-1-Inducible Collagenase Promoter Activity by Glucocorticoid Receptors

Liu

Hillmann

Harmon

1995

Molecular and Cellular Biology

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Abscisic acid-induced gene-expression requires the activity of protein(s) sensitive to the protein-tyrosine phosphatase inhibitor phenylarsine oxide

Heimovaara-Dijkstra¹,

Nieland²,

Meulen³

et al. 1996

Plant Hormone Signal Perception and Transduction

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Abscisic acid-induced gene-expression requires the activity of protein(s) sensitive to the protein-tyrosine phosphatase inhibitor phenylarsine oxide

Heimovaara-Dijkstra¹,

Nieland²,

Meulen³

et al. 1996

Plant Growth Regul

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Abscisic acid-induced gene-expression requires the activity of protein(s) sensitive to the protein-tyrosine phosphatase inhibitor phenylarsine oxide. It is generally accepted that phosphorylationldephosphorylation of proteins plays an important role in signal transduction cascades. evidence is now accumulating that for plants the same holds true. To study the role of phosphorylation in ABA signal transduction, we used six different compounds which were reported to inhibit phosphatase action. Three of these inhibitors: phenylarsine oxide (PAO), Calyculin A (CA) and Okadaic Acid (OA) appeared capable of inhibiting ABA-induced gene-expression. The same three inhibitors are shown to bring about hyperphosphorylation of two approximately 40 kDa proteins, present in the membranebound fraction of barley aleurone cells. The other three inhibitors had no visible effect on the phosphorylation status of the barley proteins. The hyperphosphorylation of the two 40 kDa proteins coincided with an increase of tyrosine-phosphorylation of two 40 kDa proteins with different p1, as determined with anti-phosphotyrosine antibodies.

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Transformation of glucocorticoid receptors bound to the antagonist RU 486: effects of alkaline phosphatase

Cited by 7 publications

References 71 publications

Hormone-Independent Repression of AP-1-Inducible Collagenase Promoter Activity by Glucocorticoid Receptors

Hormone-Independent Repression of AP-1-Inducible Collagenase Promoter Activity by Glucocorticoid Receptors

Abscisic acid-induced gene-expression requires the activity of protein(s) sensitive to the protein-tyrosine phosphatase inhibitor phenylarsine oxide

Abscisic acid-induced gene-expression requires the activity of protein(s) sensitive to the protein-tyrosine phosphatase inhibitor phenylarsine oxide

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