scholarly journals Histone Deacetylase 6–Controlled Hsp90 Acetylation Significantly Alters Mineralocorticoid Receptor Subcellular Dynamics But Not its Transcriptional Activity

Endocrinology ◽  
2016 ◽  
Vol 157 (6) ◽  
pp. 2515-2532 ◽  
Author(s):  
Rubén Jiménez-Canino ◽  
Fabián Lorenzo-Díaz ◽  
Frederic Jaisser ◽  
Nicolette Farman ◽  
Teresa Giraldez ◽  
...  

The mineralocorticoid receptor (MR) is a member of the nuclear receptor superfamily that transduces the biological effects of corticosteroids. Its best-characterized role is to enhance transepithelial sodium reabsorption in response to increased aldosterone levels. In addition, MR participates in other aldosterone- or glucocorticoid-controlled processes such as cardiovascular homeostasis, adipocyte differentiation or neurogenesis, and regulation of neuronal activity in the hippocampus. Like other steroid receptors, MR forms cytosolic heterocomplexes with heat shock protein (Hsp) 90), Hsp70, and other proteins such as immunophilins. Interaction with Hsp90 is thought to maintain MR in a ligand-binding competent conformation and to regulate ligand-dependent and -independent nucleocytoplasmatic shuttling. It has previously been shown that acetylation of residue K295 in Hsp90 regulates its interaction with the androgen receptor and glucocorticoid receptor (GR). In this work we hypothesized that Hsp90 acetylation provides a regulatory step to modulate MR cellular dynamics and activity. We used Hsp90 acetylation mimic mutant K295Q or nonacetylatable mutant K295R to examine whether MR nucleocytoplasmatic shuttling and gene transactivation are affected. Furthermore, we manipulated endogenous Hsp90 acetylation levels by controlling expression or activity of histone deacetylase 6 (HDAC6), the enzyme responsible for deacetylation of Hsp90-K295. Our data demonstrates that HDAC6-mediated Hsp90 acetylation regulates MR cellular dynamics but it does not alter its function. This stands in contrast with the down-regulation of GR by HDAC6, suggesting that Hsp90 acetylation may play a role in balancing relative MR and GR activity when both factors are co-expressed in the same cell.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3426-3426
Author(s):  
Teru Hideshima ◽  
James E. Bradner ◽  
Hiroshi Yasui ◽  
Noopur Raje ◽  
Dharminder Chauhan ◽  
...  

Abstract Histone deacetylase 6 (HDAC6) has an essential role to recruit ubiquitinated proteins to transport to aggresomes, which ultimately induces lysosomal protein degradation. We have shown that inhibition of proteasomes with bortezomib and of aggresomes with HDAC6 inhibitor Tubacin demonstrated significant cytotoxicity in MM cell lines and MM patient tumor cells in vitro (Hideshima T et al., PNAS2005, 102: 8597–8572). In this study, we further examined the biologic significance of HDAC6 inhibition by Tubacin in MM cells. We found that HDAC6 is constitutively associated with heat shock protein (Hsp) 90 in MM cell lines which is enhanced by Tubacin, as evidenced by co-immunoprecipitation. Since Akt and STAT3 have been shown to play important role in proliferation, anti-apoptosis, and drug resistance in MM cells; and all are client proteins of Hsp90, we next further examined whether inhibition of HDAC6 could modulate activities of these proteins via Hsp90. Importantly, Tubacin enhanced phosphorylation of Akt, associated with augmentation of Hsp90 acetylation. Hsp90 inhibitor 17-AAG downregulated Akt phosphorylation associated with enhanced interaction of Hsp90 with Akt, which was partially blocked by Tubacin. On the other hand, 17-AAG did not enhance acetylation of α-tubulin or ubiquitination of proteins, suggesting that Hsp90 does not affect HDAC6 function. Furthermore, we found that STAT3 is also constitutively associated with Hsp90. Importantly, both Tubacin and 17-AAG inhibit phosphorylation of STAT3 in a dose- and time-dependent fashion in MM cells. Taken together, our data indicate that HDAC6 has an important role not only in aggresomal protein degradation, but also in MM cell pathogenesis by modulating Akt and STAT3 signaling cascades via Hsp90 acetylation in MM cells.


2002 ◽  
Vol 16 (2) ◽  
pp. 253-270 ◽  
Author(s):  
Ilaria T. R. Cavarretta ◽  
Ratna Mukopadhyay ◽  
David M. Lonard ◽  
Lex M. Cowsert ◽  
C. Frank Bennett ◽  
...  

Abstract Steroid receptor RNA activator (SRA) is a novel coactivator for steroid receptors that acts as an RNA molecule, whereas steroid receptor coactivator (SRC) family members, such as steroid receptor coactivator-1 (SRC-1) and transcriptional intermediary factor 2 (TIF2) exert their biological effects as proteins. Individual overexpression of each of these coactivators, which can form multimeric complexes in vivo, results in stimulated ERα transcriptional activity in transient transfection assays. However there is no information on the consequences of reducing SRC-1, TIF2, or SRA expression, singly or in combination, on ERα transcriptional activity. We therefore developed antisense oligodeoxynucleotides (asODNs) to SRA, SRC-1, and TIF2 mRNAs, which rapidly and specifically reduced the expression of each of these coactivators. ERα-dependent gene expression was reduced in a dose-dependent fashion by up to 80% in cells transfected with these oligonucleotides. Furthermore, treatment of cells with combinations of SRA, SRC-1, and TIF2 asODNs reduced ERα transcriptional activity to an extent greater than individual asODN treatment alone, suggesting that these coactivators cooperate, in at least an additive fashion, to activate ERα-dependent target gene expression. Finally, treatment of MCF-7 cells with asODN against SRC-1 and TIF2 revealed a requirement of these coactivators, but not SRA, for hormone-dependent DNA synthesis and induction of estrogen-dependent pS2 gene expression, indicating that SRA and SRC family coactivators can fulfill specific functional roles. Taken together, we have developed a rapid method to reduce endogenous coactivator expression that enables an assessment of the in vivo role of specific coactivators on ERα biological action and avoids potential artifacts arising from overexpression of coactivators in transient transfection assays.


2011 ◽  
Vol 441 (1) ◽  
pp. 297-303 ◽  
Author(s):  
Regina T. Knapp ◽  
Andrea Steiner ◽  
Ulrike Schmidt ◽  
Kathrin Hafner ◽  
Florian Holsboer ◽  
...  

Part of the cellular and physiological functions of BAG-1 (Bcl-2-associated athanogene 1) has been ascribed to the ability of this hsp70 (heat-shock protein 70) co-chaperone to regulate steroid receptor activity. BAG-1 has been reported to inhibit the GR (glucocorticoid receptor) and stimulate the androgen receptor, but to leave the activity of the MR (mineralocorticoid receptor) unchanged. Given the high homology between the MR and GR, this disparity in the actions of BAG-1 is surprising. In the present study, we analysed the effect of BAG-1 on the activity of the closely related PR (progesterone receptor). Similarly to the GR, the transcriptional activity of the PR is inhibited by the long and middle isoforms of BAG-1, BAG-1L and BAG-1M, but not by the short isoform, BAG-1S. We found this inhibition to require the hsp70-binding domain of BAG-1. To shed light on the mechanisms that could explain BAG-1's differential actions on steroid receptors, we tested the binding of BAG-1M to the PR. Mutational analyses of the PR and BAG-1M revealed that the mode of interaction and BAG-1M-mediated inhibition of the PR differs from the reported scenario for the GR. Surprisingly, we also found binding of BAG-1M to the MR. In addition, BAG-1M was able to inhibit the transcriptional activity of the MR. These data entail a reappraisal of the physiological actions of BAG-1M on steroid receptor activity.


PLoS ONE ◽  
2015 ◽  
Vol 10 (8) ◽  
pp. e0136801 ◽  
Author(s):  
Hae-Ahm Lee ◽  
Min-Ji Song ◽  
Young-Mi Seok ◽  
Seol-Hee Kang ◽  
Sang-Yeob Kim ◽  
...  

2013 ◽  
Vol 110 (39) ◽  
pp. 15704-15709 ◽  
Author(s):  
J.-H. Lee ◽  
A. Mahendran ◽  
Y. Yao ◽  
L. Ngo ◽  
G. Venta-Perez ◽  
...  

2015 ◽  
Vol 112 (39) ◽  
pp. 12005-12010 ◽  
Author(s):  
Ju-Hee Lee ◽  
Yuanshan Yao ◽  
Adaickapillai Mahendran ◽  
Lang Ngo ◽  
Gisela Venta-Perez ◽  
...  

We report the development of a potent, selective histone deacetylase 6 (HDAC6) inhibitor. This HDAC6 inhibitor blocks growth of normal and transformed cells but does not induce death of normal cells. The HDAC6 inhibitor alone is as effective as paclitaxel in anticancer activity in tumor-bearing mice.


2004 ◽  
Vol 40 ◽  
pp. 41-58 ◽  
Author(s):  
William B Pratt ◽  
Mario D Galigniana ◽  
Yoshihiro Morishima ◽  
Patrick J M Murphy

Unliganded steroid receptors are assembled into heterocomplexes with heat-shock protein (hsp) 90 by a multiprotein chaperone machinery. In addition to binding the receptors at the chaperone site, hsp90 binds cofactors at other sites that are part of the assembly machinery, as well as immunophilins that connect the assembled receptor-hsp90 heterocomplexes to a protein trafficking pathway. The hsp90-/hsp70-based chaperone machinery interacts with the unliganded glucocorticoid receptor to open the steroid-binding cleft to access by a steroid, and the machinery interacts in very dynamic fashion with the liganded, transformed receptor to facilitate its translocation along microtubular highways to the nucleus. In the nucleus, the chaperone machinery interacts with the receptor in transcriptional regulatory complexes after hormone dissociation to release the receptor and terminate transcriptional activation. By forming heterocomplexes with hsp90, the chaperone machinery stabilizes the receptor to degradation by the ubiquitin-proteasome pathway of proteolysis.


2010 ◽  
Vol 5 (S 01) ◽  
Author(s):  
R Winkler ◽  
M Clemenz ◽  
M Bloch ◽  
A Foryst-Ludwig ◽  
C Böhm ◽  
...  

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