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Mario D. Galigniana - One of the best experts on this subject based on the ideXlab platform.
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nf κb transcriptional activity is modulated by fk506 binding proteins fkbp51 and fkbp52 a role for peptidyl prolyl isomerase activity
Journal of Biological Chemistry, 2014Co-Authors: Alejandra G. Erlejman, Maria Fernanda Camisay, Mario D. Galigniana, Gisela I. Mazaira, Marc B. Cox, Sonia A De Leo, Alejandro M Molinari, Vanina Fontana, Graciela PiwienpilipukAbstract:Hsp90 binding Immunophilins FKBP51 and FKBP52 modulate steroid receptor trafficking and hormone-dependent biological responses. With the purpose to expand this model to other nuclear factors that are also subject to nuclear-cytoplasmic shuttling, we analyzed whether these Immunophilins modulate NF-κB signaling. It is demonstrated that FKBP51 impairs both the nuclear translocation rate of NF-κB and its transcriptional activity. The inhibitory action of FKBP51 requires neither the peptidylprolyl-isomerase activity of the Immunophilin nor its association with Hsp90. The TPR domain of FKBP51 is essential. On the other hand, FKBP52 favors the nuclear retention time of RelA, its association to a DNA consensus binding sequence, and NF-κB transcriptional activity, the latter effect being strongly dependent on the peptidylprolyl-isomerase activity and also on the TPR domain of FKBP52, but its interaction with Hsp90 is not required. In unstimulated cells, FKBP51 forms endogenous complexes with cytoplasmic RelA. Upon cell stimulation with phorbol ester, the NF-κB soluble complex exchanges FKBP51 for FKBP52, and the NF-κB biological effect is triggered. Importantly, FKBP52 is functionally recruited to the promoter region of NF-κB target genes, whereas FKBP51 is released. Competition assays demonstrated that both Immunophilins antagonize one another, and binding assays with purified proteins suggest that the association of RelA and Immunophilins could be direct. These observations suggest that the biological action of NF-κB in different cell types could be positively regulated by a high FKBP52/FKBP51 expression ratio by favoring NF-κB nuclear retention, recruitment to the promoter regions of target genes, and transcriptional activity.
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regulation of the glucocorticoid response to stress related disorders by the hsp90 binding Immunophilin fkbp51
Journal of Neurochemistry, 2012Co-Authors: Natalia M Galigniana, Mariana Lagadari, Mario D. Galigniana, Alejandra G. Erlejman, Luzia T Ballmer, Judith ToneattoAbstract:Immunophilin is the collective name given to a family of proteins that bind immunosuppressive drugs: Some Immunophilins are Hsp90-binding cochaperones that affect steroid receptor function. Mood and anxiety disorders are stress-related diseases characterized by an impaired function of the mineralocorticoid and glucocorticoid receptors, two of the major regulatory elements of the hypothalamus-pituitary-adrenocortical axis. Genetic variations of the FK506-binding protein of 51-kDa, FKBP51, one of the Immunophilins bound to those steroid receptor complexes, were associated with the effectiveness of treatments against depression and with a major risk-factor for the development of post-traumatic stress disorders. Interestingly, Immunophilins show polymorphisms and some polymorphic isoforms of FKBP51 correlate with a greater impairment of steroid receptor functions. In this review, we discuss different aspects of the role of FKBP51 in such steroid receptor function and the impact of genetic variants of the Immunophilin on the dysregulation of the stress response.
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cyclophilin a is bound through its peptidylprolyl isomerase domain to the cytoplasmic dynein motor protein complex
Journal of Biological Chemistry, 2004Co-Authors: Mario D. Galigniana, Yoshihiro Morishima, Philippe Gallay, William B PrattAbstract:Although cyclophilin A (CyP-A) is a relatively abundant small Immunophilin present in the cytoplasm of all mammalian cells, its general function(s) in the absence of the immunosuppressant drug cyclosporin A is not known. In contrast, the high molecular weight hsp90-binding Immunophilins appear to play a role in protein trafficking in that they have been shown to link glucocorticoid receptor-hsp90 and p53.hsp90 complexes to the dynein motor protein for retrograde movement along microtubules. These Immunophilins link to cytoplasmic dynein indirectly through the association of the Immunophilin peptidylprolyl isomerase (PPIase) domain with dynamitin, a component of the dynein-associated dynactin complex (Galigniana, M. D., Harrell, J. M., O'Hagen, H. M., Ljungman, M., and Pratt, W. B. (2004) J. Biol. Chem. 279, 22483-22489). Here, we show that CyP-A exists in native heterocomplexes containing cytoplasmic dynein that can be formed in cell-free systems. Prolyl isomerase activity is not required for forming the dynein complex, but the PPIase domain fragment of FKBP52 blocks complex formation and CyP-A binds to dynamitin in a PPIase domain-dependent manner. CyP-A heterocomplexes containing tubulin and dynein can be formed in cytosol prepared under microtubule-stabilizing conditions, and CyP-A colocalizes in mouse fibroblasts with microtubules. Colocalization with microtubules is disrupted by overexpression of the PPIase domain fragment. Thus, we conclude that CyP-A associates in vitro and in vivo with the dynein/dynactin motor protein complex and we suggest that CyP-A may perform a general function related to the binding of cargo for retrograde movement along microtubules.
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hsp90 binding Immunophilins link p53 to dynein during p53 transport to the nucleus
Journal of Biological Chemistry, 2004Co-Authors: Mario D. Galigniana, Jennifer M Harrell, Heather M Ohagen, Mats Ljungman, William B PrattAbstract:The tumor suppressor protein p53 is known to be transported to the nucleus along microtubular tracks by cytoplasmic dynein. However, the connection between p53 and the dynein motor protein complex has not been established. Here, we show that hsp90binding Immunophilins link p53hsp90 complexes to dynein and that prevention of that linkage in vivo inhibits the nuclear movement of p53. First, we show that p53hsp90 heterocomplexes from DLD-1 human colon cancer cells contain an Immunophilin (FKBP52, CyP-40, or PP5) as well as dynein. p53hsp90Immunophilindynein complexes can be formed by incubating immunopurified p53 with rabbit reticulocyte lysate, and we show by peptide competition that the Immunophilins link via their tetratricopeptide repeat domains to p53-bound hsp90 and by means of their PPIase domains to the dynein complex. The linkage of Immunophilins to the dynein motor is indirect by means of the dynamitin component of the dynein-associated dynactin complex, and we show that purified FKBP52 binds directly by means of its PPIase domain to purified dynamitin. By using a temperaturesensitive mutant of p53 where cytoplasmic-nuclear movement occurs by shift to permissive temperature, we show that p53 movement is impeded when p53 binding to hsp90 is inhibited by the hsp90 inhibitor radicicol. Also, nuclear movement of p53 is inhibited when Immunophilin binding to dynein is competed for by expression of a PPIase domain fragment in the same manner as when dynein linkage to cargo is dissociated by expression of dynamitin. This is the first demonstration of the linkage between an hsp90-chaperoned transcription factor and the system for its retrograde movement to the nucleus both in vitro and in vivo.
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Role of hsp90 and the hsp90-binding Immunophilins in signalling protein movement.
Cellular signalling, 2004Co-Authors: William B Pratt, Mario D. Galigniana, Jennifer M Harrell, Donald B. DefrancoAbstract:The ubiquitous protein chaperone hsp90 has been shown to regulate more than 100 proteins involved in cellular signalling. These proteins are called 'client proteins' for hsp90, and a multiprotein hsp90/hsp70-based chaperone machinery forms client protein.hsp90 heterocomplexes in the cytoplasm and the nucleus. In the case of signalling proteins that act as transcription factors, the client protein.hsp90 complexes also contain one of several TPR domain Immunophilins or Immunophilin homologs that bind to a TPR domain binding site on hsp90. Using several intracellular receptors and the tumor suppressor p53 as examples, we review evidence that dynamic assembly of heterocomplexes with hsp90 is required for rapid movement through the cytoplasm to the nucleus along microtubular tracks. The role of the Immunophilin in this system is to connect the client protein.hsp90 complex to cytoplasmic dynein, the motor protein for retrograde movement toward the nucleus. Upon arrival at the nuclear pores, the receptor.hsp90.Immunophilin complexes are transferred to the nuclear interior by importin-dependent facilitated diffusion. The unliganded receptors then distribute within the nucleus to diffuse patches from which they proceed in a ligand-dependent manner to discrete nuclear foci where chromatin binding occurs. We review evidence that dynamic assembly of heterocomplexes with hsp90 is required for movement to these foci and for the dynamic exchange of transcription factors between chromatin and the nucleoplasm.
William B Pratt - One of the best experts on this subject based on the ideXlab platform.
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cyclophilin a is bound through its peptidylprolyl isomerase domain to the cytoplasmic dynein motor protein complex
Journal of Biological Chemistry, 2004Co-Authors: Mario D. Galigniana, Yoshihiro Morishima, Philippe Gallay, William B PrattAbstract:Although cyclophilin A (CyP-A) is a relatively abundant small Immunophilin present in the cytoplasm of all mammalian cells, its general function(s) in the absence of the immunosuppressant drug cyclosporin A is not known. In contrast, the high molecular weight hsp90-binding Immunophilins appear to play a role in protein trafficking in that they have been shown to link glucocorticoid receptor-hsp90 and p53.hsp90 complexes to the dynein motor protein for retrograde movement along microtubules. These Immunophilins link to cytoplasmic dynein indirectly through the association of the Immunophilin peptidylprolyl isomerase (PPIase) domain with dynamitin, a component of the dynein-associated dynactin complex (Galigniana, M. D., Harrell, J. M., O'Hagen, H. M., Ljungman, M., and Pratt, W. B. (2004) J. Biol. Chem. 279, 22483-22489). Here, we show that CyP-A exists in native heterocomplexes containing cytoplasmic dynein that can be formed in cell-free systems. Prolyl isomerase activity is not required for forming the dynein complex, but the PPIase domain fragment of FKBP52 blocks complex formation and CyP-A binds to dynamitin in a PPIase domain-dependent manner. CyP-A heterocomplexes containing tubulin and dynein can be formed in cytosol prepared under microtubule-stabilizing conditions, and CyP-A colocalizes in mouse fibroblasts with microtubules. Colocalization with microtubules is disrupted by overexpression of the PPIase domain fragment. Thus, we conclude that CyP-A associates in vitro and in vivo with the dynein/dynactin motor protein complex and we suggest that CyP-A may perform a general function related to the binding of cargo for retrograde movement along microtubules.
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hsp90 binding Immunophilins link p53 to dynein during p53 transport to the nucleus
Journal of Biological Chemistry, 2004Co-Authors: Mario D. Galigniana, Jennifer M Harrell, Heather M Ohagen, Mats Ljungman, William B PrattAbstract:The tumor suppressor protein p53 is known to be transported to the nucleus along microtubular tracks by cytoplasmic dynein. However, the connection between p53 and the dynein motor protein complex has not been established. Here, we show that hsp90binding Immunophilins link p53hsp90 complexes to dynein and that prevention of that linkage in vivo inhibits the nuclear movement of p53. First, we show that p53hsp90 heterocomplexes from DLD-1 human colon cancer cells contain an Immunophilin (FKBP52, CyP-40, or PP5) as well as dynein. p53hsp90Immunophilindynein complexes can be formed by incubating immunopurified p53 with rabbit reticulocyte lysate, and we show by peptide competition that the Immunophilins link via their tetratricopeptide repeat domains to p53-bound hsp90 and by means of their PPIase domains to the dynein complex. The linkage of Immunophilins to the dynein motor is indirect by means of the dynamitin component of the dynein-associated dynactin complex, and we show that purified FKBP52 binds directly by means of its PPIase domain to purified dynamitin. By using a temperaturesensitive mutant of p53 where cytoplasmic-nuclear movement occurs by shift to permissive temperature, we show that p53 movement is impeded when p53 binding to hsp90 is inhibited by the hsp90 inhibitor radicicol. Also, nuclear movement of p53 is inhibited when Immunophilin binding to dynein is competed for by expression of a PPIase domain fragment in the same manner as when dynein linkage to cargo is dissociated by expression of dynamitin. This is the first demonstration of the linkage between an hsp90-chaperoned transcription factor and the system for its retrograde movement to the nucleus both in vitro and in vivo.
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Role of hsp90 and the hsp90-binding Immunophilins in signalling protein movement.
Cellular signalling, 2004Co-Authors: William B Pratt, Mario D. Galigniana, Jennifer M Harrell, Donald B. DefrancoAbstract:The ubiquitous protein chaperone hsp90 has been shown to regulate more than 100 proteins involved in cellular signalling. These proteins are called 'client proteins' for hsp90, and a multiprotein hsp90/hsp70-based chaperone machinery forms client protein.hsp90 heterocomplexes in the cytoplasm and the nucleus. In the case of signalling proteins that act as transcription factors, the client protein.hsp90 complexes also contain one of several TPR domain Immunophilins or Immunophilin homologs that bind to a TPR domain binding site on hsp90. Using several intracellular receptors and the tumor suppressor p53 as examples, we review evidence that dynamic assembly of heterocomplexes with hsp90 is required for rapid movement through the cytoplasm to the nucleus along microtubular tracks. The role of the Immunophilin in this system is to connect the client protein.hsp90 complex to cytoplasmic dynein, the motor protein for retrograde movement toward the nucleus. Upon arrival at the nuclear pores, the receptor.hsp90.Immunophilin complexes are transferred to the nuclear interior by importin-dependent facilitated diffusion. The unliganded receptors then distribute within the nucleus to diffuse patches from which they proceed in a ligand-dependent manner to discrete nuclear foci where chromatin binding occurs. We review evidence that dynamic assembly of heterocomplexes with hsp90 is required for movement to these foci and for the dynamic exchange of transcription factors between chromatin and the nucleoplasm.
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review article role of hsp90 and the hsp90 binding Immunophilins in signalling protein movement
2004Co-Authors: William B Pratt, Mario D. Galigniana, Jennifer M Harrell, Donald B. DefrancoAbstract:The ubiquitous protein chaperone hsp90 has been shown to regulate more than 100 proteins involved in cellular signalling. These proteins are called ‘client proteins’ for hsp90, and a multiprotein hsp90/hsp70-based chaperone machinery forms client proteinhsp90 heterocomplexes in the cytoplasm and the nucleus. In the case of signalling proteins that act as transcription factors, the client proteinhsp90 complexes also contain one of several TPR domain Immunophilins or Immunophilin homologs that bind to a TPR domain binding site on hsp90. Using several intracellular receptors and the tumor suppressor p53 as examples, we review evidence that dynamic assembly of heterocomplexes with hsp90 is required for rapid movement through the cytoplasm to the nucleus along microtubular tracks. The role of the Immunophilin in this system is to connect the client proteinhsp90 complex to cytoplasmic dynein, the motor protein for retrograde movement toward the nucleus. Upon arrival at the nuclear pores, the receptorhsp90Immunophilin complexes are transferred to the nuclear interior by importin-dependent facilitated diffusion. The unliganded receptors then distribute within the nucleus to diffuse patches from which they procede in a ligand-dependent manner to discrete nuclear foci where chromatin binding occurs. We review evidence that dynamic assembly of heterocomplexes with hsp90 is required for movement to these foci and for the dynamic exchange of transcription factors between chromatin and the nucleoplasm.
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all of the protein interactions that link steroid receptor hsp90 Immunophilin heterocomplexes to cytoplasmic dynein are common to plant and animal cells
Biochemistry, 2002Co-Authors: Jennifer M Harrell, William B Pratt, Isaac Kurek, Adina Breiman, Christine Radanyi, Jack Michel Renoir, Mario D. GalignianaAbstract:Both plant and animal cells contain high molecular weight Immunophilins that bind via tetratricopeptide repeat (TPR) domains to a TPR acceptor site on the ubiquitous and essential protein chaperone hsp90. These hsp90-binding Immunophilins possess the signature peptidylprolyl isomerase (PPIase) domain, but no role for their PPIase activity in protein folding has been demonstrated. From the study of glucocorticoid receptor (GR).hsp90.Immunophilin complexes in mammalian cells, there is considerable evidence that both hsp90 and the FK506-binding Immunophilin FKBP52 play a role in receptor movement from the cytoplasm to the nucleus. The role of FKBP52 is to target the GR.hsp90 complex to the nucleus by binding via its PPIase domain to cytoplasmic dynein, the motor protein responsible for retrograde movement along microtubules. Here, we use rabbit cytoplasmic dynein as a surrogate for the plant homologue to show that two hsp90-binding Immunophilins of wheat, wFKBP73 and wFKBP77, bind to dynein. Binding to dynein is blocked by competition with a purified FKBP52 fragment comprising its PPIase domain but is not affected by the immunosuppressant drug FK506, suggesting that the PPIase domain but not PPIase activity is involved in dynein binding. The hsp90/hsp70-based chaperone system of wheat germ lysate assembles complexes between mouse GR and wheat hsp90. These receptor heterocomplexes contain wheat FKBPs, and they bind rabbit cytoplasmic dynein in a PPIase domain-specific manner. Retention by plants of the entire heterocomplex assembly machinery for linking the GR to dynein implies a fundamental role for this process in the biology of the eukaryotic cell.
Thomas Ratajczak - One of the best experts on this subject based on the ideXlab platform.
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Steroid Receptor-Associated Immunophilins: A Gateway to Steroid Signalling.
The Clinical biochemist. Reviews, 2015Co-Authors: Thomas Ratajczak, Carmel Cluning, Bryan K WardAbstract:The steroid receptor-associated Immunophilins FKBP51, FKBP52, CyP40 and PP5 have specific roles in steroid receptor function that impact steroid hormone-binding affinity, nucleocytoplasmic shuttling and transcriptional activation of target genes in a tissue-specific manner. Aberrant expression of these functionally unique Immunophilins has the potential to cause steroid-based diseases, including breast and prostate cancer, diabetes and related metabolic disorders, male and female infertility and major depressive disorders. This review addresses the function of these proteins as co-chaperones in steroid receptor-Hsp90 complexes and extensively covers current knowledge of the link between the steroid receptor-associated Immunophilins and human disease. An improved understanding of their mechanisms of action has revealed opportunities for molecular therapies to enhance or inhibit cellular processes under Immunophilin control that contribute both to human health and disease.
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modulation of chaperone function and cochaperone interaction by novobiocin in the c terminal domain of hsp90 evidence that coumarin antibiotics disrupt hsp90 dimerization
Journal of Biological Chemistry, 2006Co-Authors: Rudi K Allan, Danny Mok, Bryan K Ward, Thomas RatajczakAbstract:Abstract The C-terminal domain of Hsp90 displays independent chaperone activity, mediates dimerization, and contains the MEEVD motif essential for interaction with tetratricopeptide repeat-containing Immunophilin cochaperones assembled in mature steroid receptor complexes. An α-helical region, upstream of the MEEVD peptide, helps form the dimerization interface and includes a hydrophobic microdomain that contributes to the Hsp90 interaction with the Immunophilin cochaperones and corresponds to the binding site for novobiocin, a coumarin-related Hsp90 inhibitor. Mutation of selected residues within the hydrophobic microdomain significantly impacted the chaperone function of a recombinant C-terminal Hsp90 fragment and novobiocin inhibited wild-type chaperone activity. Prior incubation of the Hsp90 fragment with novobiocin led to a direct blockade of Immunophilin cochaperone binding. However, the drug had little influence on the pre-formed Hsp90-Immunophilin complex, suggesting that bound cochaperones mask the novobiocin-binding site. We observed a differential effect of the drug on Hsp90-Immunophilin interaction, suggesting that the Immunophilins make distinct contacts within the C-terminal domain to specifically modulate Hsp90 function. Novobiocin also precluded the interaction of full-length Hsp90 with the p50cdc37 cochaperone, which targets the N-terminal nucleotide-binding domain, and is prevalent in Hsp90 complexes with protein kinase substrates. Novobiocin therefore acts locally and allosterically to induce conformational changes within multiple regions of the Hsp90 protein. We provide evidence that coumermycin A1, a coumarin structurally related to novobiocin, interferes with dimerization of the Hsp90 C-terminal domain. Coumarin-based inhibitors then may antagonize Hsp90 function by inducing a conformation favoring separation of the C-terminal domains and release of substrate.
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Immunophilin chaperones in steroid receptor signalling
Current Topics in Medicinal Chemistry, 2003Co-Authors: Thomas Ratajczak, Bryan K Ward, Rodney F MinchinAbstract:The Immunophilin cochaperones, cyclophilin 40 (CyP40), FKBP51 and FKBP52 and PP5, a serine/threonine protein phosphatase, have been implicated as modulators of steroid receptor function through their association with Hsp90, a molecular chaperone with a key role in steroid hormone signalling. Although progress towards a satisfying definition for the role of these components in steroid receptor complexes has been slow, recent developments arising from novel approaches in both yeast and mammalian systems, together with available crystal structures for Hsp90 and some of these cochaperones, are beginning to provide important clues about their function. Hsp90, recently identified as a member of the GHKL superfamily of ATPases, is the central player in receptor assembly, an energy-driven process that allows receptor and the Immunophilins to be proximally located, or to interact directly, on a Hsp90 scaffold. Immunophilin structure, relative abundance, their binding affinity for Hsp90 and their ability to interact with specific receptors may all contribute to a selective preference of the Immunophilins for individual receptors. Association of receptors with different Immunophilins leads to differential functional consequences for receptor activity. Observations of glucocorticoid resistance in New World primates, attributed to FKBP51 overexpression and incorporation into glucocorticoid receptor complexes, have provided the first evidence that these cochaperones can control hormone-binding affinity. Application of a yeast model to FKBP52 function in the glucocorticoid receptor system has now provided crucial evidence that this Immunophilin enhances receptor transcriptional activity by increasing receptor avidity for hormone through PPIase-mediated conformational changes in the ligand-binding domain. A recent novel finding suggests that hormone binding may induce a functional exchange of Immunophilins in receptor complexes and that the modified complex directs receptor to the nucleus.
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The Hsp90-binding peptidylprolyl isomerase FKBP52 potentiates glucocorticoid signaling in vivo
EMBO Journal, 2003Co-Authors: Daniel L. Riggs, Patricia J. Roberts, Samantha C. Chirillo, Joyce Cheung-flynn, Richard Gaber, Viravan Prapapanich, Thomas Ratajczak, Didier Picard, David F SmithAbstract:Hsp90 is required for the normal activity of steroid receptors, and in steroid receptor complexes it is typically bound to one of the Immunophilin-related co-chaperones: the peptidylprolyl isomerases FKBP51, FKBP52 or CyP40, or the protein phosphatase PP5. The physiological roles of the Immunophilins in regulating steroid receptor function have not been well defined, and so we examined in vivo the influences of Immunophilins on hormone-dependent gene activation in the Saccharomyces cerevisiae model for glucocorticoid receptor (GR) function. FKBP52 selectively potentiates hormone-dependent reporter gene activation by as much as 20-fold at limiting hormone concentrations, and this potentiation is readily blocked by co-expression of the closely related FKBP51. The mechanism for potentiation is an increase in GR hormone-binding affinity that requires both the Hsp90-binding ability and the prolyl isomerase activity of FKBP52.
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estradiol regulated expression of the Immunophilins cyclophilin 40 and fkbp52 in mcf 7 breast cancer cells
Biochemical and Biophysical Research Communications, 2001Co-Authors: Thomas Ratajczak, Bryan K Ward, Peter J Mark, Rodney F Minchin, Premlata KumarAbstract:The Immunophilins, cyclophilin 40 (CyP40) and FKBP52, are associated with the unactivated estrogen receptor in mutually exclusive heterocomplexes and may differentially modulate receptor activity. We have recently shown that CyP40 and FKBP52 mRNA's are differentially elevated in breast carcinomas compared with normal breast tissue. Other studies suggest that such alterations in the ratio of Immunophilins might potentially influence steroid receptor function. Studies were therefore initiated to investigate the influence of estradiol on CyP40 and FKBP52 expression in MCF-7 breast cancer cells. Over a 24-h-treatment period with estradiol, CyP40 and FKBP52 mRNA expression was increased approximately five- and 14-fold, respectively. The corresponding protein levels were also elevated in comparison to controls. The antiestrogen, ICI 182,780, was an antagonist for CyP40 and FKBP52 mRNA induction. Cycloheximide treatment did not inhibit this increased Immunophilin expression, suggesting that estradiol-mediated activation is independent of de novo protein synthesis. Treatment of MCF-7 cells with estradiol resulted in an increased half-life of both CyP40 and FKBP52 mRNA, as determined by actinomycin D studies. These results suggest that estradiol regulates CyP40 and FKBP52 mRNA expression through both transcriptional and posttranscriptional mechanisms.
Sheng Luan - One of the best experts on this subject based on the ideXlab platform.
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Chloroplast-Localized, Heat Shock- Responsive
2014Co-Authors: From Fava Bean, Sheng Luan, William A S. Lane, Stuart Schreiber L. ‘iAbstract:When the immunosuppressants cyclosporin A (CsA) and FK506 bind to their intracellular receptors (Immunophilins), they form complexes that bind to calcineurin and block calcineurin-dependent signaling pathways in immune cells. Previ-ously, we reported that higher plants also express Immunophilins and have a Ca2+-dependent signaling pathway sensitive to Immunophilin-ligand complexes. Based on an N-terminal peptide sequence of a chloroplast-localized cyclophilin (pCyP B), we isolated a cDNA clone encoding the preprotein of the cyclophilin. The deduced amino acid sequence of this cDNA starts with a putative transit sequence for chloroplast targeting. The mature pCyP B protein has rotamase activity with low-substrate specificity. Enzyme activity was inhibited by CsA with an inhibition constant of 3.9 nM. Similar to other CyPs from mammalian cells, pCyP B, when complexed with CsA, inhibited the phosphatase activity of bovine calcineurin. The mRNA leve1 of pCyP B was high in leaf tissues but was not detectable in roots. Expression of the transcript in the leaf tissues was regulated by light and induced by heat shock. These findings illustrate the conserved nature of cyclophi-lin proteins among all of the eukaryotes and suggest that cyclophilins have a unique mode of regulation in higher plants
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plant Immunophilins functional versatility beyond protein maturation
New Phytologist, 2005Co-Authors: Julie E Gray, Patrick S Romano, Peter Horton, Sheng LuanAbstract:Contents Summary 1 I. A historical perspective 2 II. The mechanism of immunosuppression 2 III. PPIase activity and protein folding 3 IV. Immunophilins are ubiquitous proteins 3 V. Plant Immunophilins 5 VI. Specific functions of plant Immunophilins 7 VII. Concluding remarks 13 References 13 Summary Originally identified as the cellular targets of immunosuppressant drugs, the Immunophilins encompass two ubiquitous protein families: the FK-506 binding proteins or FKBPs, and the cyclosporin-binding proteins or cyclophilins. Present in organisms ranging from bacteria to animals and plants, these proteins are characterized by their enzymatic activity; the peptidyl–prolyl cis–trans isomerization of polypeptides. Whilst this function is important for protein folding, it has formed the functional basis for more complex interactions between Immunophilins and their target proteins. Beginning with a brief historical overview of the Immunophilin family, and a representative illustration of the current state of knowledge that has accumulated for these proteins in diverse organisms, a detailed description is presented of the recent advances in the elucidation of the role of this ubiquitous protein family in plant biology. Though still in its infancy, investigation into the function of plant Immunophilins has so far yielded interesting results – as a significant component of the chloroplast proteome, the abundance of Immunophilins located in the thylakoid lumen suggests that these proteins may play important roles in this relatively uncharacterized subcellular compartment. Moreover, the importance of the complex multidomain Immunophilins in functions pertaining to development is underscored by the strong phenotypes displayed by their corresponding mutants.
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Immunophilins and parvulins superfamily of peptidyl prolyl isomerases in arabidopsis
Plant Physiology, 2004Co-Authors: Sheng LuanAbstract:Immunophilins are defined as receptors for immunosuppressive drugs including cyclosporin A, FK506, and rapamycin. The cyclosporin A receptors are referred to as cyclophilins (CYPs) and FK506- and rapamycin-binding proteins are abbreviated as FKBPs. These two groups of proteins (collectively called Immunophilins) share little sequence homology, but both have peptidyl prolyl cis/trans isomerase (PPIase) activity that is involved in protein folding processes. Studies have identified Immunophilins in all organisms examined including bacteria, fungi, animals, and plants. Nevertheless, the physiological function of Immunophilins is poorly understood in any organism. In this study, we have surveyed the genes encoding Immunophilins in Arabidopsis genome. A total of 52 genes have been found to encode putative Immunophilins, among which 23 are putative FKBPs and 29 are putative CYPs. This is by far the largest Immunophilin family identified in any organism. Both FKBPs and CYPs can be classified into single domain and multiple domain members. The single domain members contain a basic catalytic domain and some of them have signal sequences for targeting to a specific organelle. The multiple domain members contain not only the catalytic domain but also defined modules that are involved in protein-protein interaction or other functions. A striking feature of Immunophilins in Arabidopsis is that a large fraction of FKBPs and CYPs are localized in the chloroplast, a possible explanation for why plants have a larger Immunophilin family than animals. Parvulins represent another family of PPIases that are unrelated to Immunophilins in protein sequences and drug binding properties. Three parvulin genes were found in Arabidopsis genome. The expression of many Immunophilin and parvulin genes is ubiquitous except for those encoding chloroplast members that are often detected only in the green tissues. The large number of genes and diversity of structure domains and cellular localization make PPIases a versatile superfamily of proteins that clearly function in many cellular processes in plants.
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pcyp b a chloroplast localized heat shock responsive cyclophilin from fava bean
The Plant Cell, 1994Co-Authors: Sheng Luan, William S Lane, Stuart L. SchreiberAbstract:When the immunosuppressants cyclosporin A (CsA) and FK506 bind to their intracellular receptors (immunophillins), they form complexes that bind to calcineurin and block calcineurin-dependent signaling pathways in immune cells. Previously, we reported that higher plants also express Immunophilins and have a Ca(2+)-dependent signaling pathway sensitive to Immunophilin-ligand complexes. Based on an N-terminal peptide sequence of a chloroplast-localized cyclophilin (pCyP B), we isolated a cDNA clone encoding the preprotein of the cyclophilin. The deduced amino acid sequence of this cDNA starts with a putative transit sequence for chloroplast targeting. The mature pCyP B protein has rotamase activity with low-substrate specificity. Enzyme activity was inhibited by CsA with an inhibition constant of 3.9 nM. Similar to other CyPs from mammalian cells, pCyP B, when complexed with CsA, inhibited the phosphatase activity of bovine calcineurin. The mRNA level of pCyP B was high in leaf tissue but was not detectable in roots. Expression of the transcript in the leaf tissues was regulated by light and induced by heat shock. These findings illustrate the conserved nature of cyclophilin proteins among all of the eukaryotes and suggest that cyclophilins have a unique mode of regulation in higher plants.
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Light-regulated, tissue-specific Immunophilins in a higher plant
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Sheng Luan, Mark W. Albers, Stuart L. SchreiberAbstract:In addition to their application in organ transplantation, immunosuppressive drugs are valuable tools for studying signal transduction in eukaryotic cells. Using affinity chromatography, we have purified immunosuppressive drug receptors (Immunophilins) from fava bean. Proteins belonging to both major classes of the Immunophilin family identified from animal sources [FK506- and rapamycin-binding proteins (FKBPs) and cyclophilins] were present in this higher plant. FKBP13, the most abundant FKBP family member in leaf tissues, was not detected in root tissues, whereas other FKBPs were present in both tissues. While the abundance of cyclophilin A in leaves was similar to that in roots, cyclophilin B/C was expressed at a much higher level in leaf tissues than in root tissues. Subcellular localization of Immunophilins in mesophyll cells showed that chloroplasts contained FKBP13 and cyclophilin B/C but not other members, which explains the preferential expression of these two proteins in leaves over roots. The abundance of chloroplast-localized Immunophilins, FKBP13 and cyclophilin B/C, was regulated by light. Although etiolated leaves produced detectable levels of cyclophilin B/C, they did not express FKBP13. Illumination of etiolated plants dramatically increased the expression of both FKBP13 and cyclophilin B/C. The light-induced expression of FKBP13 is closely correlated with the accumulation of chlorophyll in the leaf tissue. Our findings suggest that FKBP13 and cyclophilin B/C may play a specific role in chloroplasts.
David F Smith - One of the best experts on this subject based on the ideXlab platform.
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deficiency of co chaperone Immunophilin fkbp52 compromises sperm fertilizing capacity
Reproduction, 2007Co-Authors: Jiyoung Hong, David F Smith, Sung Tae Kim, Susanne Tranguch, Sudhansu K DeyAbstract:FKBP52 is a member of the FK506-binding family of Immunophilins and serves as a co-chaperone for steroid hormone nuclear receptors to govern appropriate hormone action in target tissues. Male mice missing Fkbp52 are infertile, and this infertility has been ascribed to compromised sensitivity of the anterior prostate, external genitalia, and other accessory sex organs to androgen. Here, we show additional defects contributing to infertility. We found that epididymal Fkbp52(-/-) sperm are sparse often with aberrant morphology, and they have reduced fertilizing capacity. This phenotype, initially observed in null males on a C57BL/6/129 background, is also maintained on a CD1 background. Expression studies show that while FKBP52 and androgen receptor are co-expressed in similar cell types in the epididymis, FKBP52 is also present in epididymal sperm flagella. Collectively, our results suggest that reduced number and abnormal morphology contribute to compromised fertilizing capacity of Fkbp52(-/-) sperm. This study is clinically relevant because unraveling the role of Immunophilin signaling in male fertility will help identify new targets for male contraceptives and/or alleviate male infertility.
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structure of the large fk506 binding protein fkbp51 an hsp90 binding protein and a component of steroid receptor complexes
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Cindy R Sinars, David F Smith, Joyce Cheungflynn, Ronald A Rimerman, Jonathan G Scammell, Jon ClardyAbstract:The ability to bind immunosuppressive drugs such as cyclosporin and FK506 defines the Immunophilin family of proteins, and the FK506-binding proteins form the FKBP subfamily of Immunophilins. Some FKBPs, notably FKBP12 (the 12-kDa FK506-binding protein), have defined roles in regulating ion channels or cell signaling, and well established structures. Other FKBPs, especially the larger ones, participate in important biological processes, but their exact roles and the structural bases for these roles are poorly defined. FKBP51 (the 51-kDa FKBP) associates with heat shock protein 90 (Hsp90) and appears in functionally mature steroid receptor complexes. In New World monkeys, FKBP51 has been implicated in cortisol resistance. We report here the x-ray structures of human FKBP51, to 2.7 A, and squirrel monkey FKBP51, to 2.8 A, by using multiwavelength anomalous dispersion phasing. FKBP51 is composed of three domains: two consecutive FKBP domains and a three-unit repeat of the TPR (tetratricopeptide repeat) domain. This structure of a multi-FKBP domain protein clarifies the arrangement of these domains and their possible interactions with other proteins. The two FKBP domains differ by an insertion in the second that affects the formation of the progesterone receptor complex.
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The Hsp90-binding peptidylprolyl isomerase FKBP52 potentiates glucocorticoid signaling in vivo
EMBO Journal, 2003Co-Authors: Daniel L. Riggs, Patricia J. Roberts, Samantha C. Chirillo, Joyce Cheung-flynn, Richard Gaber, Viravan Prapapanich, Thomas Ratajczak, Didier Picard, David F SmithAbstract:Hsp90 is required for the normal activity of steroid receptors, and in steroid receptor complexes it is typically bound to one of the Immunophilin-related co-chaperones: the peptidylprolyl isomerases FKBP51, FKBP52 or CyP40, or the protein phosphatase PP5. The physiological roles of the Immunophilins in regulating steroid receptor function have not been well defined, and so we examined in vivo the influences of Immunophilins on hormone-dependent gene activation in the Saccharomyces cerevisiae model for glucocorticoid receptor (GR) function. FKBP52 selectively potentiates hormone-dependent reporter gene activation by as much as 20-fold at limiting hormone concentrations, and this potentiation is readily blocked by co-expression of the closely related FKBP51. The mechanism for potentiation is an increase in GR hormone-binding affinity that requires both the Hsp90-binding ability and the prolyl isomerase activity of FKBP52.
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molecular cloning of human fkbp51 and comparisons of Immunophilin interactions with hsp90 and progesterone receptor
Molecular and Cellular Biology, 1997Co-Authors: Satish C Nair, Viravan Prapapanich, Ronald A Rimerman, E J Toran, Shiying Chen, R N Butts, David F SmithAbstract:A cDNA for human FKBP51 has been cloned and sequenced, and protein products have been expressed in both in vitro and bacterial systems. The deduced amino acid sequence for human FKBP51 is 90% identical to sequences of recently described murine proteins and is 55% identical to the sequence of human FKBP52. Human FKBP51 mRNA is expressed in a wide range of tissues, and the protein has peptidylprolyl isomerase activity that is inhibited by FK506 but not cyclosporine. FKBP51 is the same as a previously described progesterone receptor-associated Immunophilin that, similar to FKBP52 and cyclophilin 40, is an Hsp90binding protein and appears in functionally mature steroid receptor complexes along with Hsp90 and p23. Each of the three receptor-associated Immunophilins displays interactions with progesterone receptor that are more dynamic than Hsp90-receptor interactions. Whereas FKBP52 and FKBP51 compete about equally well for binding to Hsp90 in a purified system, FKBP51 accumulates preferentially in progesterone receptor complexes assembled in a cell-free system. This observation provides a precedent for differential interactions between Hsp90-associated Immunophilins and target proteins such as steroid receptors. In the absence of hormone, progesterone receptor (PR) normally exists in hetero-oligomeric complexes with various components of the molecular chaperone machinery. The functionally mature progesterone receptor complex, which is competent for high-affinity progesterone binding, contains Hsp90, p23, and an Immunophilin component; however, formation of the mature complex is preceded by PR interactions with chaperone components not present in the mature PR complex (33, 38). These earlier transient components include Hsp70, Hip, and Hop (p60). Hsp90 also appears at an intermediate assembly stage, but its interaction with the PR complex is biochemically distinct from its interaction in mature complexes (3). Three Immunophilins have been identified in steroid receptor complexes, and it appears that multiple Immunophilins do not reside in the same receptor complex. Present evidence suggests that the Immunophilins enter receptor complexes in