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Mario D. Galigniana - One of the best experts on this subject based on the ideXlab platform.
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biological actions of the hsp90 binding Immunophilins fkbp51 and fkbp52
2019Co-Authors: Nadia R Zgajnar, Alejandra G. Erlejman, Sonia A De Leo, Graciela Piwienpilipuk, Cecilia M Lotufo, Mario D. GalignianaAbstract:Immunophilins are a family of proteins whose signature domain is the peptidylprolyl-isomerase domain. High molecular weight Immunophilins are characterized by the additional presence of tetratricopeptide-repeats (TPR) through which they bind to the 90-kDa heat-shock protein (Hsp90), and via this chaperone, Immunophilins contribute to the regulation of the biological functions of several client-proteins. Among these Hsp90-binding Immunophilins, there are two highly homologous members named FKBP51 and FKBP52 (FK506-binding protein of 51-kDa and 52-kDa, respectively) that were first characterized as components of the Hsp90-based heterocomplex associated to steroid receptors. Afterwards, they emerged as likely contributors to a variety of other hormone-dependent diseases, stress-related pathologies, psychiatric disorders, cancer, and other syndromes characterized by misfolded proteins. The differential biological actions of these Immunophilins have been assigned to the structurally similar, but functionally divergent enzymatic domain. Nonetheless, they also require the complementary input of the TPR domain, most likely due to their dependence with the association to Hsp90 as a functional unit. FKBP51 and FKBP52 regulate a variety of biological processes such as steroid receptor action, transcriptional activity, protein conformation, protein trafficking, cell differentiation, apoptosis, cancer progression, telomerase activity, cytoskeleton architecture, etc. In this article we discuss the biology of these events and some mechanistic aspects.
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biological relevance of hsp90 binding Immunophilins in cancer development and treatment
2016Co-Authors: Gisela I. Mazaira, Maria Fernanda Camisay, Mario D. Galigniana, Alejandra G. Erlejman, Sonia A De LeoAbstract:Immunophilins are a family of intracellular receptors for immunosuppressive drugs. Those Immunophilins that are related to immunosuppression are the smallest proteins of the family, i.e., FKBP12 and CyPA, whereas the other members of the family have higher molecular weight because the show additional domains to the drug-binding site. Among these extra domains, the TPR-domain is perhaps the most relevant because it permits the interaction of high molecular weight Immunophilins with the 90-kDa heat-shock protein, Hsp90. This essential molecular chaperone regulates the biological function of several protein-kinases, oncogenes, protein phosphatases, transcription factors and cofactors . Hsp90-binding Immunophilins where first characterized due to their association with steroid receptors. They regulate the cytoplasmic transport and the subcellular localization of these and other Hsp90 client proteins, as well as transcriptional activity, cell proliferation, cell differentiation and apoptosis. Hsp90-binding Immunophilins are frequently overexpressed in several types of cancers and play a key role in cell survival. In this article we analyze the most important biological actions of the best characterized Hsp90-binding Immunophilins in both steroid receptor function and cancer development and discuss the potential use of these Immunophilins for therapeutic purposes as potential targets of specific small molecules.
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Regulation of NF-κB signalling cascade by Immunophilins
2015Co-Authors: Mariana Lagadari, Maria Fernanda Camisay, Mario D. Galigniana, Alejandra G. ErlejmanAbstract:Abstract The fine regulation of signalling cascades is a key event required to maintain the appropriate functional properties of a cell when a given stimulus triggers specific biological responses. In this sense, cumulative experimental evidence during the last years has shown that high molecular weight Immunophilins possess a fundamental importance in the regulation of many of these processes. It was first discovered that TPR-domain Immunophilins such as FKBP51 and FKBP52 play a cardinal role, usually in an antagonistic fashion, in the regulation of several members of the steroid receptor family via its interaction with the heat-shock protein of 90-kDa, Hsp90. These Hsp90-associated cochaperones form a functional unit with the molecular chaperone influencing ligand binding capacity, receptor trafficking, and hormone-dependent transcriptional activity. Recently, it was demonstrated that the same Immunophilins are also able to regulate the NF-kB signalling cascade in an Hsp90 independent manner. In this article we analize these properties and discuss the relevance of this novel regulatory pathway in the context of the pleiotropic actions managed by NF-kB in several cell types and tissues.
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nf κb transcriptional activity is modulated by fk506 binding proteins fkbp51 and fkbp52 a role for peptidyl prolyl isomerase activity
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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hsp90 binding Immunophilins link p53 to dynein during p53 transport to the nucleus
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.
William B Pratt - One of the best experts on this subject based on the ideXlab platform.
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hsp90 binding Immunophilins link p53 to dynein during p53 transport to the nucleus
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.
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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binding of hsp90 associated Immunophilins to cytoplasmic dynein direct binding and in vivo evidence that the peptidylprolyl isomerase domain is a dynein interaction domain
2002Co-Authors: Mario D. Galigniana, Jennifer M Harrell, Jackmichel Renoir, Patrick J Murphy, Michael Chinkers, Christine Radanyi, Mingjie Zhang, William B PrattAbstract:FKBP52 is a steroid receptor-associated immunophilin that binds via a tetratricopeptide repeat (TPR) domain to hsp90. FKBP52 has also been shown to interact either directly or indirectly via its peptidylprolyl isomerase (PPIase) domain with cytoplasmic dynein, a motor protein involved in retrograde transport of vesicles toward the nucleus. The functional role for the PPIase domain in receptor movement was demonstrated by showing that expression of the PPIase domain fragment of FKBP52 in 3T3 cells inhibits dexamethasone-dependent nuclear translocation of a green fluorescent protein-glucocorticoid receptor chimera. Here, we show that cytoplasmic dynein is co-immunoadsorbed with two other TPR domain proteins that bind hsp90 (the cyclophilin CyP-40 and the protein phosphatase PP5). Both proteins possess PPIase homology domains, and co-immunoadsorption of cytoplasmic dynein with each is blocked by the PPIase domain fragment of FKBP52. Using purified proteins, we show that FKBP52, PP5, and the PPIase domain fragment bind directly to the intermediate chain of cytoplasmic dynein. PP5 colocalizes with both cytoplasmic dynein and microtubules, and expression of the PPIase domain fragment of FKBP52 in 3T3 cells disrupts its cytoskeletal localization. We conclude that the PPIase domains of the hsp90-binding Immunophilins interact directly with cytoplasmic dynein and that this interaction with the motor protein is responsible for the microtubular localization of PP5 in vivo.
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a model for the cytoplasmic trafficking of signalling proteins involving the hsp90 binding Immunophilins and p50cdc37
1999Co-Authors: William B Pratt, Adam M Silverstein, Mario D. GalignianaAbstract:Abstract A number of transcription factors and protein kinases involved in signal transduction exist in heterocomplexes with the ubiquitous and essential protein chaperone hsp90. These signalling protein·hsp90 heterocomplexes are assembled by a multiprotein chaperone system comprising hsp90, hsp70, Hop, hsp40, and p23. In the case of transcription factors, the heterocomplexes with hsp90 also contain a high molecular weight immunophilin with tetratricopeptide repeat (TPR) motifs, such as FKBP52 or CyP-40. In the case of the protein kinases, the heterocomplexes contain p50cdc37. The Immunophilins bind to a single TPR acceptor site on hsp90, and p50cdc37 binds to an adjacent site so that binding is exclusive for p50cdc37 or an immunophilin. Direct interaction of Immunophilins with the transcription factors or p50cdc37 with the protein kinases leads to selection of different heterocomplexes after their assembly by a common mechanism. Studies with the glucocorticoid receptor, for which translocation from the cytoplasm to the nucleus is under hormonal control, suggest that dynamic assembly of the heterocomplexes is required for rapid movement of the receptor through the cytoplasm along cytoskeletal tracts. As for the similar short-range trafficking of vesicles along microtubules, there must be a mechanism for linking the signalling protein solutes to the molecular motors involved in movement. We present here a model in which the Immunophilins and p50cdc37 target, respectively, the retrograde or anterograde direction of signalling protein movement by functioning as connectors that link the signalling proteins to the movement machinery.
Sheng Luan - One of the best experts on this subject based on the ideXlab platform.
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plant Immunophilins a review of their structure function relationship
2015Co-Authors: Dileep Vasudevan, Sheng Luan, Gayathri Gopalan, Ashish Kumar, Veder J Garcia, Kunchithapadam SwaminathanAbstract:Abstract Background Originally discovered as receptors for immunosuppressive drugs, Immunophilins consist of two major groups, FK506 binding proteins (FKBPs) and cyclosporin A binding proteins (cyclophilins, CYPs). Many members in both FKBP and CYP families are peptidyl prolyl isomerases that are involved in protein folding processes, though they share little sequence homology. It is not surprising to find Immunophilins in all organisms examined so far, including viruses, bacteria, fungi, plants and animals, as protein folding represents a common process in all living systems. Scope of Review Studies on plant Immunophilins have revealed new functions beyond protein folding and new structural properties beyond that of typical PPIases. This review focuses on the structural and functional diversity of plant FKBPs and CYPs. Major Conclusions The differences in sequence, structure as well as subcellular localization, have added on to the diversity of this family of molecular chaperones. In particular, the large number of Immunophilins present in the thylakoid lumen of the photosynthetic organelle, promises to deliver insights into the regulation of photosynthesis, a unique feature of plant systems. However, very little structural information and functional data are available for plant Immunophilins. General Significance Studies on the structure and function of plant Immunophilins are important in understanding their role in plant biology. By reviewing the structural and functional properties of some Immunophilins that represent the emerging area of research in plant biology, we hope to increase the interest of researchers in pursuing further research in this area. This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets.
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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
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
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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Immunophilins in animals and higher plants
1998Co-Authors: Sheng LuanAbstract:Immunophilins were originally discovered as receptors for a family of immunosuppressive drugs including cyclosporin, FK506, and rapamycin. These drugs suppress immune reaction and are clinically used to prevent graft rejection during organ transplantation. More recently, Immunophilins have been found in all eukaryotes ranging from yeast, animals, and higher plants, implicating these proteins in foundamental cellular processes. Biochemical analyses have shown that all Immunophilins studied so far possess an enzyme activity involved in protein folding. However, a number of more specific functions for Immunophilins have also been discovered in mammalian systems. Although research on plant Immunophilins is more primitive, ongoing studies suggest that these proteins may play unique roles in plant growth and development. This article will briefly summarize research activities on both animal and plant Immunophilins, a promising new area of current biology.
Alejandra G. Erlejman - One of the best experts on this subject based on the ideXlab platform.
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biological actions of the hsp90 binding Immunophilins fkbp51 and fkbp52
2019Co-Authors: Nadia R Zgajnar, Alejandra G. Erlejman, Sonia A De Leo, Graciela Piwienpilipuk, Cecilia M Lotufo, Mario D. GalignianaAbstract:Immunophilins are a family of proteins whose signature domain is the peptidylprolyl-isomerase domain. High molecular weight Immunophilins are characterized by the additional presence of tetratricopeptide-repeats (TPR) through which they bind to the 90-kDa heat-shock protein (Hsp90), and via this chaperone, Immunophilins contribute to the regulation of the biological functions of several client-proteins. Among these Hsp90-binding Immunophilins, there are two highly homologous members named FKBP51 and FKBP52 (FK506-binding protein of 51-kDa and 52-kDa, respectively) that were first characterized as components of the Hsp90-based heterocomplex associated to steroid receptors. Afterwards, they emerged as likely contributors to a variety of other hormone-dependent diseases, stress-related pathologies, psychiatric disorders, cancer, and other syndromes characterized by misfolded proteins. The differential biological actions of these Immunophilins have been assigned to the structurally similar, but functionally divergent enzymatic domain. Nonetheless, they also require the complementary input of the TPR domain, most likely due to their dependence with the association to Hsp90 as a functional unit. FKBP51 and FKBP52 regulate a variety of biological processes such as steroid receptor action, transcriptional activity, protein conformation, protein trafficking, cell differentiation, apoptosis, cancer progression, telomerase activity, cytoskeleton architecture, etc. In this article we discuss the biology of these events and some mechanistic aspects.
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biological relevance of hsp90 binding Immunophilins in cancer development and treatment
2016Co-Authors: Gisela I. Mazaira, Maria Fernanda Camisay, Mario D. Galigniana, Alejandra G. Erlejman, Sonia A De LeoAbstract:Immunophilins are a family of intracellular receptors for immunosuppressive drugs. Those Immunophilins that are related to immunosuppression are the smallest proteins of the family, i.e., FKBP12 and CyPA, whereas the other members of the family have higher molecular weight because the show additional domains to the drug-binding site. Among these extra domains, the TPR-domain is perhaps the most relevant because it permits the interaction of high molecular weight Immunophilins with the 90-kDa heat-shock protein, Hsp90. This essential molecular chaperone regulates the biological function of several protein-kinases, oncogenes, protein phosphatases, transcription factors and cofactors . Hsp90-binding Immunophilins where first characterized due to their association with steroid receptors. They regulate the cytoplasmic transport and the subcellular localization of these and other Hsp90 client proteins, as well as transcriptional activity, cell proliferation, cell differentiation and apoptosis. Hsp90-binding Immunophilins are frequently overexpressed in several types of cancers and play a key role in cell survival. In this article we analyze the most important biological actions of the best characterized Hsp90-binding Immunophilins in both steroid receptor function and cancer development and discuss the potential use of these Immunophilins for therapeutic purposes as potential targets of specific small molecules.
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Regulation of NF-κB signalling cascade by Immunophilins
2015Co-Authors: Mariana Lagadari, Maria Fernanda Camisay, Mario D. Galigniana, Alejandra G. ErlejmanAbstract:Abstract The fine regulation of signalling cascades is a key event required to maintain the appropriate functional properties of a cell when a given stimulus triggers specific biological responses. In this sense, cumulative experimental evidence during the last years has shown that high molecular weight Immunophilins possess a fundamental importance in the regulation of many of these processes. It was first discovered that TPR-domain Immunophilins such as FKBP51 and FKBP52 play a cardinal role, usually in an antagonistic fashion, in the regulation of several members of the steroid receptor family via its interaction with the heat-shock protein of 90-kDa, Hsp90. These Hsp90-associated cochaperones form a functional unit with the molecular chaperone influencing ligand binding capacity, receptor trafficking, and hormone-dependent transcriptional activity. Recently, it was demonstrated that the same Immunophilins are also able to regulate the NF-kB signalling cascade in an Hsp90 independent manner. In this article we analize these properties and discuss the relevance of this novel regulatory pathway in the context of the pleiotropic actions managed by NF-kB in several cell types and tissues.
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The Emerging Role of TPR-Domain Immunophilins in the Mechanism of Action of Steroid Receptors
2014Co-Authors: Gisela I. Mazaira, Mariana Lagadari, Alejandra G. ErlejmanAbstract:In the absence of ligand, some members of nuclear receptor family such as corticosteroid receptors are primarily located in the cytoplasm, and they rapidly accumulate in the nucleus upon ligand-binding. Other members of the family such as the estrogen receptor are mostly nuclear. Regardless of their primary location, these oligomeric proteins undergo a dynamic nuclear-cytoplasmic shuttling, and their transport through the cytoplasmic compartment has always been assumed to occur in a stochastic manner by simple diffusion. Although heuristic, this oversimplified model has never been demonstrated. Moreover, it has always been assumed that the first step related to receptor activation is the dissociation of the Hsp90-based heterocomplex, a process referred to as `transformation.' Nonetheless, recent experimental evidence indicates that the chaperone machinery is required for the retrotransport of the receptor throughout the cytoplasm and facilitates its active passage through the nuclear pore. Therefore, transformation is actually a nuclear event. A group of Hsp90-binding cochaperones belonging to the immunophilin family plays a cardinal role not only in the mechanism for receptor movement, but also in nuclear events leading to interactions with nuclear sites of action and the regulation of transcriptional activity. In this article we analyze the importance of molecular chaperones and TPR-domain Immunophilins in the molecular mechanism of action of steroid receptors.
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nf κb transcriptional activity is modulated by fk506 binding proteins fkbp51 and fkbp52 a role for peptidyl prolyl isomerase activity
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.
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
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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c terminal sequences outside the tetratricopeptide repeat domain of fkbp51 and fkbp52 cause differential binding to hsp90
2003Co-Authors: Joyce Cheungflynn, Patricia J. Roberts, Daniel L. Riggs, David F SmithAbstract:Abstract Hsp90 assembles with steroid receptors and other client proteins in association with one or more Hsp90-binding cochaperones, some of which contain a common tetratricopeptide repeat (TPR) domain. Included in the TPR cochaperones are the Hsp70-Hsp90-organizing protein Hop, the FK506-binding Immunophilins FKBP52 and FKBP51, the cyclosporin A-binding immunophilin CyP40, and protein phosphatase PP5. The TPR domains from these proteins have similar x-ray crystallographic structures and target cochaperone binding to the MEEVD sequence that terminates Hsp90. However, despite these similarities, the TPR cochaperones have distinctive properties for binding Hsp90 and assembling with Hsp90·steroid receptor complexes. To identify structural features that differentiate binding of FKBP51 and FKBP52 to Hsp90, we generated an assortment of truncation mutants and chimeras that were compared for coimmunoprecipitation with Hsp90. Although the core TPR domain (approximately amino acids 260–400) of FKBP51 and FKBP52 is required for Hsp90 binding, the C-terminal 60 amino acids (∼400-end) also influence Hsp90 binding. More specifically, we find that amino acids 400–420 play a critical role for Hsp90 binding by either FKBP. Within this 20-amino acid region, we have identified a consensus sequence motif that is also present in some other TPR cochaperones. Additionally, the final 30 amino acids of FKBP51 enhance binding to Hsp90, whereas the corresponding region of FKBP52 moderates binding to Hsp90. Taking into account the x-ray crystal structure for FKBP51, we conclude that the C-terminal regions of FKBP51 and FKBP52 outside the core TPR domains are likely to assume alternative conformations that significantly impact Hsp90 binding.
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structure of the large fk506 binding protein fkbp51 an hsp90 binding protein and a component of steroid receptor complexes
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
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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two fkbp related proteins are associated with progesterone receptor complexes
1993Co-Authors: David F Smith, B A Baggenstoss, T N Marion, Ronald A RimermanAbstract:Abstract Unactivated steroid receptors are in heterooligomeric complexes that perhaps stabilize a partially folded receptor polypeptide prior to hormone-dependent activation. Hsp90 is a common receptor component and hsp70 is a component of progesterone receptors; both appear to be important as general mediators of protein folding and assembly events. In addition to hsp90, mammalian steroid receptor complexes contain a 52-59-kDa protein that is an FK506-binding immunophilin and has peptidyl-prolyl isomerase activity. Other receptor-associated proteins have been identified but not well-characterized. In the present study, we obtained partial amino acid sequences for two avian progesterone receptor components, p50 and p54. From sequence comparisons with known proteins, they appear to be distinct members of the FKBP family of Immunophilins. Six p50 peptide sequences have 80% identity with regions of rabbit FKBP52; seven p54 peptide sequences have 60% identity with rabbit FKBP52. Interaction of p54 with receptor is distinct from p50 in that its binding in vitro is highly sensitive to progesterone or N-ethylmaleimide. An anti-p54 monoclonal antibody was developed that detects a 55-kDa protein in rabbit and human tissues; in a cell-free reconstitution system, the rabbit antigen binds to chicken progesterone receptor along with rFKBP52. While p50 appears to be the chicken homolog of FKBP52, p54 is perhaps a novel member of the FKBP family that, in addition to FKBP52, interacts with progesterone receptor.
