Evidence that the hormone binding domain of steroid receptors confers hormonal control on chimeric proteins by determining their hormone-regulated binding to heat-shock protein 90

Biochemistry ◽  
1993 ◽  
Vol 32 (20) ◽  
pp. 5381-5386 ◽  
Author(s):  
Lawrence C. Scherrer ◽  
Didier Picard ◽  
Enrique Massa ◽  
Jeffrey M. Harmon ◽  
S. Stoney Simons ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Steroid Receptors ◽  
Heat Shock Protein 90 ◽  
Hormonal Control ◽  
Binding Domain ◽  
Chimeric Proteins ◽  
Hormone Binding ◽  
Hormone Binding Domain

scholarly journals A Role for the Hsp40 Ydj1 in Repression of Basal Steroid Receptor Activity in Yeast

2000 ◽  
Vol 20 (9) ◽  
pp. 3027-3036 ◽  
Author(s):  
Jill L. Johnson ◽  
Elizabeth A. Craig
Keyword(s):  
Glucocorticoid Receptor ◽  
Steroid Receptors ◽  
Hormonal Control ◽  
Binding Domain ◽  
Receptor Activity ◽  
Hormone Binding ◽  
Mutant Strains ◽  
Elevated Activity ◽  
Carboxy Terminal ◽  
Hormone Binding Domain

ABSTRACT In addition to its roles in translocation of preproteins across membranes, Ydj1 facilitates the maturation of Hsp90 substrates, including mammalian steroid receptors, which activate transcription in yeast in a hormone-dependent manner. To better understand Ydj1's function, we have constructed and analyzed an array of Ydj1 mutants in vivo. Both the glucocorticoid receptor and the estrogen receptor exhibited elevated activity in the absence of hormone in allydj1 mutant strains, indicating a strict requirement for Ydj1 activity in hormonal control. Glucocorticoid receptor containing a mutation in the carboxy-terminal transcriptional activation domain, AF-2, retained elevated basal activity, while mutation of the amino-terminal transactivation domain, AF-1, eliminated the elevated basal activity observed in ydj1 mutant strains. This result indicates that the source of activity is AF-1, which is normally repressed by the carboxy-terminal hormone binding domain in the absence of hormone. Chimeric proteins containing the hormone binding domain of the estrogen or glucocorticoid receptor fused to heterologous activation and DNA binding domains also exhibited elevated activity in the absence of hormone. Thus, Ydj1 mutants appear to increase basal receptor activity by altering the ability of the hormone binding domain of the receptor to repress nearby activation domains. We propose that Ydj1 functions to present steroid receptors to the Hsp90 pathway for folding and hormonal control. In the presence of Ydj1 mutants that fail to bind substrate efficiently, some receptor escapes the Hsp90 pathway, resulting in constitutive activity.

scholarly journals Cyclophilin-40: evidence for a dimeric complex with hsp90

1995 ◽  
Vol 307 (1) ◽  
pp. 5-8 ◽  
Author(s):  
K Hoffmann ◽  
R E Handschumacher
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Fusion Protein ◽  
Steroid Receptors ◽  
Heat Shock Protein 90 ◽  
Binding Activity ◽  
Dimeric Complex ◽  
Glutathione S Transferase ◽  
High Concentration ◽  
Cyclophilin 40

The expression of human cyclophilin 40 (CyP-40) as a glutathione S-transferase fusion protein has provided a means to identify cellular components that are in association with this ubiquitous protein. When the fusion protein was coupled to a GSH affinity matrix, heat-shock protein 90 (hsp90) was found to be the predominant associated protein in all tissue extracts examined. The relatively high concentration of each of these proteins in various tissues indicates that the dimeric complex exists in concentrations that exceed those of the inactive steroid receptors of which each protein is a component. Association does not occur with heat-shock protein 70 and is not affected by cyclosporin A (CsA). Independent expression of two domains of CyP-40 permitted dissociation of N-terminal isomerase and CsA binding activity from the hsp90 binding site, which is located at the FKBP-59-like C-terminal region. The biological association of CyP-40 with hsp90 in many tissues may reflect a conjoint role in protein folding and trafficking.

scholarly journals The Heat Shock Protein 90 Antagonist Novobiocin Interacts with a Previously Unrecognized ATP-binding Domain in the Carboxyl Terminus of the Chaperone

2000 ◽  
Vol 275 (47) ◽  
pp. 37181-37186 ◽  
Author(s):  
Monica G. Marcu ◽  
Ahmed Chadli ◽  
Ilham Bouhouche ◽  
Maria Catelli ◽  
Leonard M. Neckers
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Protein 90 ◽  
Binding Domain ◽  
Carboxyl Terminus ◽  
Atp Binding

scholarly journals Chromatin Recycling of Glucocorticoid Receptors: Implications for Multiple Roles of Heat Shock Protein 90

1999 ◽  
Vol 13 (3) ◽  
pp. 355-365 ◽  
Author(s):  
Jimin Liu ◽  
Donald B. DeFranco
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Nuclear Export ◽  
Glucocorticoid Receptors ◽  
Binding Capacity ◽  
Heat Shock Protein 90 ◽  
Multiple Roles ◽  
Chromatin Binding ◽  
Hormone Binding ◽  
Permeabilized Cells

Abstract Unliganded glucocorticoid receptors (GRs) released from chromatin after hormone withdrawal remain associated with the nucleus within a novel subnuclear compartment that serves as a nuclear export staging area. We set out to examine whether unliganded nuclear receptors cycle between distinct subnuclear compartments or require cytoplasmic transit to regain hormone and chromatin-binding capacity. Hormone-withdrawn rat GrH2 hepatoma cells were permeabilized with digitonin to deplete cytoplasmic factors, and then hormone-binding and chromatin-binding properties of the recycled nuclear GRs were measured. We found that recycled nuclear GRs do not require cytosolic factors or ATP to rebind hormone. Nuclear GRs that rebind hormone in permeabilized cells target to high-affinity chromatin-binding sites at 30 C, but not 0 C, in the presence of ATP. Since geldanamycin, a heat shock protein-90 (hsp90)-binding drug, inhibits hormone binding to recycled nuclear GRs, hsp90 may be required to reassemble the receptor into a form capable of productive interactions with hormone. Geldanamycin also inhibits GR release from chromatin during hormone withdrawal, suggesting that hsp90 chaperone function may play multiple roles to facilitate chromatin recycling of GR.

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