scholarly journals Carboxyl Terminus of hsc70-Interacting Protein (CHIP) Can Remodel Mature Aryl Hydrocarbon Receptor (AhR) Complexes and Mediate Ubiquitination of Both the AhR and the 90 kDa Heat-Shock Protein (hsp90)in Vitro†

Biochemistry ◽  
2007 ◽  
Vol 46 (2) ◽  
pp. 610-621 ◽  
Author(s):  
J. Luis Morales ◽  
Gary H. Perdew
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Aryl Hydrocarbon Receptor ◽  
Protein Chip ◽  
Carboxyl Terminus ◽  
Interacting Protein ◽  
Aryl Hydrocarbon

scholarly journals Transformation of the aryl hydrocarbon receptor to a DNA-binding form is accompanied by release of the 90 kDa heat-shock protein and increased affinity for 2,3,7,8-tetrachlorodibenzo-p-dioxin

1993 ◽  
Vol 294 (1) ◽  
pp. 95-101 ◽  
Author(s):  
E C Henry ◽  
T A Gasiewicz
Keyword(s):  
Heat Shock ◽  
Dna Binding ◽  
Heat Shock Protein ◽  
Aryl Hydrocarbon Receptor ◽  
Incubation Temperature ◽  
Binding Affinities ◽  
Aryl Hydrocarbon ◽  
Molecular Events ◽  
Binding Forms ◽  
Tetrachlorodibenzo P Dioxin

The binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to the aryl hydrocarbon receptor (AhR) elicits a sequence of poorly defined molecular events that ultimately yield a heteromeric transformed AhR that is active as a transcription factor. We have previously developed a model of the ligand-initiated transformation of the AhR to the DNA-binding state based on characterization of several forms of the AhR with respect to their physicochemical properties and DNA-binding affinities. The present studies were designed to determine whether, and at what stage, this process of transformation alters the receptor's affinity for TCDD. In rat hepatic cytosol, approx. 10% of the TCDD specifically bound to the AhR rapidly dissociated (t1/2 approximately 1 h), while the remainder was only slowly dissociable (t1/2 approximately 70 h). The isolated DNA-binding forms of the receptor (monomeric and transformed) bound TCDD very tightly (t1/2 > 100 h), whereas TCDD was dissociable from the non-DNA-binding receptor form(s). A lower incubation temperature (0-4 degrees C) and the presence of molybdate partially stabilized the non-DNA-binding fraction of the TCDD.receptor complex and also enhanced TCDD dissociation in crude cytosol. Immunoprecipitation of the different AhR forms with an anti-AhR antibody and immunoblotting with antibody to the 90 kDa heat-shock protein (hsp90) demonstrated that hsp90 was associated with the unoccupied receptor complex as well as with a fraction of the non-DNA-binding TCDD.receptor complex; isolated DNA-binding forms did not contain detectable hsp90. We conclude that while hsp90 remains associated with the AhR, TCDD is readily dissociable; following release of hsp90, however, TCDD becomes very tightly bound, and remains so upon completion of transformation.

scholarly journals p23 protects the human aryl hydrocarbon receptor from degradation via a heat shock protein 90-independent mechanism

2018 ◽  
Vol 152 ◽  
pp. 34-44 ◽  
Author(s):  
Beverly Pappas ◽  
Yujie Yang ◽  
Yu Wang ◽  
Kyung Kim ◽  
Hee Jae Chung ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Aryl Hydrocarbon Receptor ◽  
Heat Shock Protein 90 ◽  
Aryl Hydrocarbon ◽  
Independent Mechanism

MicroRNA miR-107 is overexpressed in pituitary adenomas and inhibits the expression of aryl hydrocarbon receptor-interacting protein in vitro

2012 ◽  
Vol 303 (6) ◽  
pp. E708-E719 ◽  
Author(s):  
Giampaolo Trivellin ◽  
Henriett Butz ◽  
Juliette Delhove ◽  
Susana Igreja ◽  
Harvinder S. Chahal ◽  
...  
Keyword(s):  
Pituitary Adenoma ◽  
Tumor Suppressor ◽  
Aryl Hydrocarbon Receptor ◽  
Pituitary Adenomas ◽  
Expression Profiles ◽  
Luciferase Assay ◽  
Human Neuroblastoma ◽  
Interacting Protein ◽  
Aryl Hydrocarbon

Abnormal microRNA (miRNA) expression profiles have recently been associated with sporadic pituitary adenomas, suggesting that miRNAs can contribute to tumor formation; miRNAs are small noncoding RNAs that inhibit posttranscriptional expression of target mRNAs by binding to target sequences usually located in the 3′-UTR. In this study, we investigated the role played by miR-107, a miRNA associated with different human cancers, in sporadic pituitary adenomas and its interaction with the pituitary tumor suppressor gene aryl hydrocarbon receptor-interacting protein ( AIP). miR-107 expression was evaluated in pituitary adenoma and normal pituitary samples using microRNA screen TLDA (TaqMan Low-Density Array) and RT-qPCR assays. We show that miR-107 expression was significantly upregulated in GH-secreting and nonfunctioning pituitary adenomas. We found that human AIP-3′-UTR is a target of miR-107 since miR-107 inhibited in vitro AIP expression to 53.9 ± 2% of the miRNA control in a luciferase assay and reduced endogenous AIP mRNA expression to 53 ± 22% of the miRNA control in human cells. However, we did not observe a negative correlation between AIP and miR-107 expression in the human tumor samples. Furthermore, we show that miR-107 overexpression inhibited cell proliferation in human neuroblastoma and rat pituitary adenoma cells. In conclusion, miR-107 is overexpressed in pituitary adenomas and may act as a tumor suppressor. We have identified and confirmed AIP as a miR-107 target gene. Expression data in human samples suggest that the expression of AIP and miR-107 could be influenced by a combination of tumorigenic factors as well as compensatory mechanisms stimulated by the tumorigenic process.

scholarly journals Somatostatin analogues increase AIP expression in somatotropinomas, irrespective of Gsp mutations

2013 ◽  
Vol 20 (5) ◽  
pp. 753-766 ◽  
Author(s):  
Marie-Lise Jaffrain-Rea ◽  
Sandra Rotondi ◽  
Annarita Turchi ◽  
Gianluca Occhi ◽  
Anne Barlier ◽  
...  
Keyword(s):  
Pituitary Adenoma ◽  
Aryl Hydrocarbon Receptor ◽  
Primary Cultures ◽  
Gene Mutations ◽  
Somatostatin Analogues ◽  
Interacting Protein ◽  
Aryl Hydrocarbon ◽  
Tumour Shrinkage ◽  
Suprasellar Extension

Germline aryl hydrocarbon receptor interacting protein (AIP) gene mutations confer a predisposition to pituitary adenoma (PA), predominantly GH-secreting (GH-PA). As recent data suggest a role for AIP in the pathogenesis of sporadic GH-PA and their response to somatostatin analogues (SSA), the expression of AIP and its partner, aryl hydrocarbon receptor (AHR), was determined by semiquantitative immunohistochemistry scoring in 62 sporadic GH-PA (37 treated with SSA preoperatively). The influence ofGspstatus was studied in a subset of tumours (n=39, 14Gsp+) and six GH-PA were available for primary cultures. AIP and AHR were detected in most cases, with a positive correlation between AIP and cytoplasmic AHR (P=0.012). Low AIP expression was significantly more frequent in untreated vs SSA-treated tumours (44.0 vs 20.5%,P=0.016). AHR expression or localisation did not differ between the two groups. Similarly,in vitrooctreotide induced a median twofold increase in AIP expression (range 1.2–13.9,P=0.027) in GH-PA. In SSA-treated tumours, the AIP score was significantly higher in the presence of preoperative IGF1 decrease or tumour shrinkage (P=0.008 andP=0.014 respectively). In untreated tumours, low AIP expression was significantly associated with invasiveness (P=0.028) and suprasellar extension (P=0.019). The only effect ofGspstatus was a significantly lower nuclear AHR score inGsp+vsGsp−tumours (P=0.025), irrespective of SSA. In conclusion, AIP is involved in the aggressiveness of sporadic GH-PA, regardless ofGspstatus, and AIP up-regulation in SSA-treated tumours is associated with a better preoperative response, with no clear role for AHR.

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