Essential Role of the Unusual DNA-binding Motif of BAG-1 for Inhibition of the Glucocorticoid Receptor

Schmidt, Ulrike; Wochnik, Gabriela M.; Rosenhagen, M.; Young, Jason C.; Hartl, F. Ulrich; Holsboer, Florian; Rein, Theo

doi:10.1074/jbc.m212000200

Cited by 54 publications

(68 citation statements)

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“…Previous studies have already demonstrated that Hsp70 selectively targets the TPR domains in SGT1 (41) and heat-shock organizing protein (Hop) (42), whereas CyP40 (43) and carboxy terminus of Hsc-70 interacting protein (CHIP) (44) are less discriminatory and can bind either Hsp90 or Hsc70. The outer mitochondrial membrane transporter Tom-70 is also a TPR protein able to provide a docking site for both chaperones, favoring the mitochondrial import of proteins (45,46). This makes Tom-70 a possible carrier for FKBP51.…”

Section: Discussionmentioning

confidence: 99%

The 90-kDa Heat-shock Protein (Hsp90)-binding Immunophilin FKBP51 Is a Mitochondrial Protein That Translocates to the Nucleus to Protect Cells against Oxidative Stress

Gallo

Lagadari

Piwien-Pilipuk

et al. 2011

Journal of Biological Chemistry

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Confocal microscopy images revealed that the tetratricopeptide repeat motif (TPR) domain immunophilin FKBP51 shows colocalization with the specific mitochondrial marker MitoTracker. Signal specificity was tested with different antibodies and by FKBP51 knockdown. This unexpected subcellular localization of FKBP51 was confirmed by colocalization studies with other mitochondrial proteins, biochemical fractionation, and electron microscopy imaging. Interestingly, FKBP51 forms complexes in mitochondria with the glucocorticoid receptor and the Hsp90/Hsp70-based chaperone heterocomplex. Although Hsp90 inhibitors favor FKBP51 translocation from mitochondria to the nucleus in a reversible manner, TPR domain-deficient mutants of FKBP51 are constitutively nuclear and fully excluded from mitochondria, suggesting that a functional TPR domain is required for its mitochondrial localization. FKBP51 overexpression protects cells against oxidative stress, whereas FKBP51 knockdown makes them more sensitive to injury. In summary, this is the first demonstration that FKBP51 is a major mitochondrial factor that undergoes nuclearmitochondrial shuttling, an observation that may be related to antiapoptotic mechanisms triggered during the stress response.Immunophilins comprise a family of intracellular proteins classified by their ability to bind immunosuppressant drugs. Thus, cyclophilins bind cyclosporine A, whereas FK506-binding proteins (FKBPs) 3 bind FK506. The signature domain of the family is the PPIase domain, which shows peptidylprolyl-cis/ trans-isomerase enzymatic activity in most of the members of the family and is also the binding site of the drug. The low molecular weight immunophilins FKBP12 and CyPA are related to the immunosuppressive effect when the drug⅐ immunophilin complex inhibits the Ser/Thr-phosphatase activity of PP2B (calcineurin). On the other hand, high molecular weight immunophilins do not play a significant role in immunosuppression. This subfamily shows the FKBP12-like PPIase domains 1 and 2 (also called FK1 and FK2) and the tetratricopeptide repeat motif (TPR) domains (1, 2), which contain degenerative sequences of 34 amino acids repeated in tandem through which they bind to Hsp90. The FK1 domain is responsible for the ability of the proteins to bind FK506 and to confer enzymatic activity (3), and it is also the primary regulatory domain required for steroid hormone receptor regulation (4).TPR domain proteins exhibit a large degree of sequence diversity, but the structural comparison reveals a highly conserved three-dimensional structure. Individual TPR domains are composed of two antiparallel ␣-helices separated by a turn. Multiple TPR domains arrange at regular angles and form a right-handed superhelix. This creates a groove with a large amount of surface area available for ligand binding (5, 6). Multiprotein complexes are assembled via this 34-amino acid scaffold motif. In addition to high molecular weight immunophilins, the TPR family includes a large variety of several factors such as the anaphase-p...

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Section: Discussionmentioning

confidence: 99%

The 90-kDa Heat-shock Protein (Hsp90)-binding Immunophilin FKBP51 Is a Mitochondrial Protein That Translocates to the Nucleus to Protect Cells against Oxidative Stress

Gallo

Lagadari

Piwien-Pilipuk

et al. 2011

Journal of Biological Chemistry

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“…Cell Culture, Transfection, and Assays for Luciferase and ␤-Galactosidase-Cultivation and transfection of human neuroblastoma SK-N-MC cells (American Type Culture Collection catalog number HTB-10), HeLa cells, HEK, and H4-II-E-C3 cells were as described previously (29,30). Two days before transfection, cells were seeded in medium containing charcoal-stripped serum.…”

Section: Methodsmentioning

confidence: 99%

FK506-binding Proteins 51 and 52 Differentially Regulate Dynein Interaction and Nuclear Translocation of the Glucocorticoid Receptor in Mammalian Cells

Wochnik

Rüegg

Abel

et al. 2005

Journal of Biological Chemistry

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We used a cellular system to elucidate the molecular determinants of the large immunophilin FK506-binding proteins (FKBP)51 and -52 for their action on the glucocorticoid receptor in mammalian cells. Increasing the levels of FKBP51 reduced the transcriptional activity of the receptor, as reported. Elevated levels of FKBP52 per se showed no effect but mitigated the inhibition of the receptor induced by FKBP51. We discovered that nuclear translocation of the glucocorticoid receptor was delayed by FKBP51. This correlates with the reduced interaction of FKBP51 with the motor protein dynein compared with FKBP52. From mutational analyses, we concluded that three features of the immunophilins are required for efficient receptor signaling in mammalian cells: hsp90 interaction, dynein association, and peptidylprolyl isomerase (PPIase) enzyme activity. The relevance of dynein for receptor function was substantiated by several experiments: 1) coexpression of dynamitin, which disrupts the transport complex and reduces receptor activity; 2) coexpression of the PPIase domain fragment of FKBP52, which is known to disrupt interaction of the receptor to dynein and reduce glucocorticoid receptor function, in contrast to the corresponding fragment of FKBP51; and 3) swapping of the PPIase domains FKBP51 and FKBP52, which reverses the respective activity. We concluded from our results that the mechanisms of the regulatory system FKBP51/FKBP52 discovered in yeast also operate in mammals to modulate hormone binding of the receptor. In addition, differential regulation of dynein association and nuclear translocation contributes to the effects of the two immunophilins on the glucocorticoid receptor in mammals.

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“…Bag-1 proteins have been shown to act as cochaperones that modulate the activity of Hsc70/Hsp70 (Hohfeld and Jentsch, 1997;Takayama et al, 1997;Zeiner et al, 1997) and to bind and activate the serine/threonine kinase Raf-1 (Wang et al, 1996). Bag-1 proteins also bind to a variety of protein tyrosine kinase receptors (Bardelli et al, 1996) and nuclear hormone receptors (Zeiner and Gehring, 1995;Liu et al, 1998;Witcher et al, 2001;Schmidt et al, 2003). Bag-1 is expressed by a variety of cell types, including chondrocytes, during development and in adult tissues Crocoll et al, 2000).…”

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confidence: 99%

Age‐related expression patterns of Bag‐1 and Bcl‐2 in growth plate and articular chondrocytes

et al. 2004

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Aging cartilage displays increased chondrocyte apoptosis and decreased responsiveness of chondrocytes to growth factors. The molecular mechanisms responsible for these changes have not been identified. Bag-1 is a Bcl-2-binding protein that promotes cell survival, interacts with a diverse group of cellular proteins, and may integrate multiple pathways involved in controlling cell survival, growth, and phenotype. Bcl-2 is important for maintaining chondrocyte phenotype and delaying terminal differentiation and apoptosis of chondrocytes. Comparatively little is known about the role of Bag-1 in cartilage. Here we show that both growth plate and articular chondrocytes in the mouse express the Bag-1 protein. In the growth plate, Bag-1 expression is prominent in the late proliferative and prehypertrophic chondrocytes, displaying a pattern similar to what has been reported for Bcl-2. Further, the expression of both Bcl-2 and Bag-1 declines with age in the articular cartilage. Growth assays demonstrate that knocking down Bag-1 expression causes a decrease in growth rate. These results suggest that Bag-1 is involved in the regulation of chondrocyte phenotype and cartilage aging.

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Essential Role of the Unusual DNA-binding Motif of BAG-1 for Inhibition of the Glucocorticoid Receptor

Cited by 54 publications

References 60 publications

The 90-kDa Heat-shock Protein (Hsp90)-binding Immunophilin FKBP51 Is a Mitochondrial Protein That Translocates to the Nucleus to Protect Cells against Oxidative Stress

The 90-kDa Heat-shock Protein (Hsp90)-binding Immunophilin FKBP51 Is a Mitochondrial Protein That Translocates to the Nucleus to Protect Cells against Oxidative Stress

FK506-binding Proteins 51 and 52 Differentially Regulate Dynein Interaction and Nuclear Translocation of the Glucocorticoid Receptor in Mammalian Cells

Age‐related expression patterns of Bag‐1 and Bcl‐2 in growth plate and articular chondrocytes

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