Structure, Function and Regulation of the Hsp90 Machinery
TL;DR: The recent progress made in understanding the Hsp90 machinery is discussed, which influences the conformational cycle, co-chaperone interaction, and inter-domain communications.
Abstract: Heat shock protein 90 (Hsp90) is an ATP-dependent molecular chaperone which is essential in eukaryotes It is required for the activation and stabilization of a wide variety of client proteins and many of them are involved in important cellular pathways Since Hsp90 affects numerous physiological processes such as signal transduction, intracellular transport, and protein degradation, it became an interesting target for cancer therapy Structurally, Hsp90 is a flexible dimeric protein composed of three different domains which adopt structurally distinct conformations ATP binding triggers directionality in these conformational changes and leads to a more compact state To achieve its function, Hsp90 works together with a large group of cofactors, termed co-chaperones Co-chaperones form defined binary or ternary complexes with Hsp90, which facilitate the maturation of client proteins In addition, posttranslational modifications of Hsp90, such as phosphorylation and acetylation, provide another level of regulation They influence the conformational cycle, co-chaperone interaction, and inter-domain communications In this review, we discuss the recent progress made in understanding the Hsp90 machinery
Citations
More filters
TL;DR: This review gives a general overview of protein acetylation and the respective acetyltransferases, and focuses on the regulation of metabolic processes and physiological consequences that come along with proteinacetylation.
547 citations
TL;DR: This manuscript will review the general structure, regulation and function of HSP90 family and their potential role in pathophysiology.
Abstract: The mammalian HSP90 family of proteins is a cluster of highly conserved molecules that are involved in myriad cellular processes Their distribution in various cellular compartments underlines their essential roles in cellular homeostasis HSP90 and its co-chaperones orchestrate crucial physiological processes such as cell survival, cell cycle control, hormone signaling, and apoptosis Conversely, HSP90, and its secreted forms, contribute to the development and progress of serious pathologies, including cancer and neurodegenerative diseases Therefore, targeting HSP90 is an attractive strategy for the treatment of neoplasms and other diseases This manuscript will review the general structure, regulation and function of HSP90 family and their potential role in pathophysiology
309 citations
TL;DR: The activity of different UPRs involved in tumorigenesis and resistance to cancer therapy are described, which seems to adjust the paradoxical microenvironment of cancer and is one of resistance mechanisms against cancer therapy.
Abstract: The endoplasmic reticulum (ER) is the principal organelle responsible for multiple cellular functions including protein folding and maturation and the maintenance of cellular homeostasis. ER stress is activated by a variety of factors and triggers the unfolded protein response (UPR), which restores homeostasis or activates cell death. Multiple studies have clarified the link between ER stress and cancer, and particularly the involvement of the UPR. The UPR seems to adjust the paradoxical microenvironment of cancer and, as such, is one of resistance mechanisms against cancer therapy. This review describes the activity of different UPRs involved in tumorigenesis and resistance to cancer therapy.
277 citations
TL;DR: The role of intracellular and extracellular STI1 and the Hsp70/Hsp90 chaperone network in mechanisms underlying protein misfolding in neurodegenerative diseases, with particular focus on AD is discussed.
Abstract: TThe accumulation of misfolded proteins in the human brain is one of the critical features of many neurodegenerative diseases, including Alzheimer’s disease (AD). Assembles of beta-amyloid (Aβ) peptide – either soluble (oligomers - Aβ) or insoluble (plaques) and of tau protein, which form neurofibrillary tangles, are the major hallmarks of AD. Chaperones and co-chaperones regulate protein folding and client maturation, but they also target misfolded or aggregated proteins for refolding or for degradation, mostly by the proteasome. They form an important line of defense against misfolded proteins and are part of the cellular quality control system. The heat shock protein (Hsp) family, particularly Hsp70 and Hsp90, plays a major part in this process and it is well known to regulate protein misfolding in a variety of diseases, including tau levels and toxicity in AD. However, the role of Hsp90 in regulating protein misfolding is not yet fully understood. For example, knockdown of Hsp90 and its co-chaperones in a C. elegans model of Aβ misfolding leads to increased toxicity. On the other hand, the use of Hsp90 inhibitors in AD mouse models reduces Aβ toxicity, and normalizes synaptic function. Stress-inducible phosphoprotein 1 (STI1), an intracellular co-chaperone, mediates the transfer of clients from Hsp70 to Hsp90. Importantly, STI1 has been shown to regulate aggregation of amyloid-like proteins in yeast. In addition to its intracellular function, STI1 can be secreted by diverse cell types, including astrocytes and microglia and function as a neurotrophic ligand by triggering signaling via the cellular prion protein (PrPC). Extracellular STI1 can prevent Aβ toxic signaling by (i) interfering with Aβ binding to PrPC and (ii) triggering pro-survival signaling cascades. Interestingly, decreased levels of STI1 in C. elegans can also increase toxicity in an amyloid model. In this review, we will discuss the role of intracellular and extracellular STI1 and the Hsp70/Hsp90 chaperone network in mechanisms underlying protein misfolding in neurodegenerative diseases, with particular focus on Alzheimer’s disease.
245 citations
Cites background from "Structure, Function and Regulation ..."
...Post-translational modifications of Hsp90 include acetylation, nitrosylation, phosphorylation, and methylation, which has been elegantly reviewed by Li and Buchner (2013)....
[...]
TL;DR: This protocol discusses how to use data obtained in affinity purification–mass spectrometry experiments to generate meaningful interaction networks and effective figures, and explores methods available in Cytoscape to visualize and analyze these types of interaction data.
Abstract: By determining protein-protein interactions in normal, diseased and infected cells, we can improve our understanding of cellular systems and their reaction to various perturbations. In this protocol, we discuss how to use data obtained in affinity purification-mass spectrometry (AP-MS) experiments to generate meaningful interaction networks and effective figures. We begin with an overview of common epitope tagging, expression and AP practices, followed by liquid chromatography-MS (LC-MS) data collection. We then provide a detailed procedure covering a pipeline approach to (i) pre-processing the data by filtering against contaminant lists such as the Contaminant Repository for Affinity Purification (CRAPome) and normalization using the spectral index (SIN) or normalized spectral abundance factor (NSAF); (ii) scoring via methods such as MiST, SAInt and CompPASS; and (iii) testing the resulting scores. Data formats familiar to MS practitioners are then transformed to those most useful for network-based analyses. The protocol also explores methods available in Cytoscape to visualize and analyze these types of interaction data. The scoring pipeline can take anywhere from 1 d to 1 week, depending on one's familiarity with the tools and data peculiarities. Similarly, the network analysis and visualization protocol in Cytoscape takes 2-4 h to complete with the provided sample data, but we recommend taking days or even weeks to explore one's data and find the right questions.
152 citations
References
More filters
TL;DR: S-nitrosylation conveys a large part of the ubiquitous influence of nitric oxide on cellular signal transduction, and provides a mechanism for redox-based physiological regulation.
Abstract: S-nitrosylation, the covalent attachment of a nitrogen monoxide group to the thiol side chain of cysteine, has emerged as an important mechanism for dynamic, post-translational regulation of most or all main classes of protein. S-nitrosylation thereby conveys a large part of the ubiquitous influence of nitric oxide (NO) on cellular signal transduction, and provides a mechanism for redox-based physiological regulation.
2,006 citations
"Structure, Function and Regulation ..." refers background in this paper
...S‐nitrosylation is a reversible covalent modification of reactive cysteine thiols in proteins by nitric oxide (NO).([109,110]) Mammalian Hsp90 is a target of S‐nitrosylation mediated by NO produced by its client protein, endothelial nitric oxide synthase (eNOS)....
[...]
TL;DR: A historical perspective on a body of steroid receptor research dealing with the structure and physiological significance of the untransformed 9S receptor is provided, and it is shown that hsp90 itself exists in a variety of native multiprotein heterocomplexes independent of steroid receptors and other 'substrate' proteins.
Abstract: We have provided a historical perspective on a body of steroid receptor research dealing with the structure and physiological significance of the untransformed 9S receptor that has often confused both novice and expert investigators. The frequent controversies and equivocations of earlier studies were due to the fact that the native, hormone-free state of these receptors is a large multiprotein complex that resisted description for many years because of its unstable and dynamic nature. The untransformed 9S state of the steroid and dioxin receptors has provided a unique system for studying the function of the ubiquitous, abundant, and conserved heat shock protein, hsp90. The hormonal control of receptor association with hsp90 provided a method of manipulating the receptor heterocomplex in a manner that was physiologically meaningful. For several steroid receptors, binding to hsp90 was required for the receptor to be in a native hormone-binding state, and for all of the receptors, hormone binding promoted dissociation of the receptor from hsp90 and conversion of the receptor to the DNA-binding state. Although the complexes between tyrosine kinases and hsp90 were discovered earlier, the hormonal regulation or steroid receptor association with hsp90 permitted much more rapid and facile study of hsp90 function. The observations that hsp90 binds to the receptors through their HBDs and that these domains can be fused to structurally different proteins bringing their function under hormonal control provided a powerful linkage between the hormonal regulation of receptor binding to hsp90 and the initial step in steroid hormone action. Because the 9S receptor hsp90 heterocomplexes could be physically stabilized by molybdate, their protein composition could be readily studied, and it became clear that these complexes are multiprotein structures containing a number of unique proteins, such as FKBP51, FKBP52, CyP-40, and p23, that were discovered because of their presence in these structures. Further analysis showed that hsp90 itself exists in a variety of native multiprotein heterocomplexes independent of steroid receptors and other 'substrate' proteins. Cell-free systems can now be used to study the formation of receptor heterocomplexes. As we outlined in the scheme of Fig. 1, the multicomponent receptor-hsp90 heterocomplex assembly system is being reconstituted, and the importance of individual proteins, such as hsp70, p60, and p23, in the assembly process is becoming recognized. It should be noted that our understanding of the mechanism and purpose of steroid receptor heterocomplex assembly is still at an early stage. We can now speculate on the roles of receptor-associated proteins in receptor action, both as individuals and as a group, but their actual functions are still vague or unknown. We can make realistic models about the chaperoning and trafficking of steroid receptors, but we don't yet know how these processes occur, we don't know where chaperoning occurs in the cell (e.g. Is it limited to the cytoplasm? Is it a diffuse process or does chaperoning occur in association with structural elements?), and, with the exception of the requirement for hormone binding, we don't know the extent to which the hsp90-based chaperone system impacts on steroid hormone action. It is not yet clear how far the discovery of this hsp90 heterocomplex assembly system will be extended to the development of a general understanding of protein processing in the cell. Because this assembly system is apparently present in all eukaryotic cells, it probably performs an essential function for many proteins. The bacterial homolog of hsp90 is not an essential protein, but hsp90 is essential in eukaryotes, and recent studies indicate that the development of the cell nucleus from prokaryotic progenitors was accompanied by the duplication of genes for hsp90 and hsp70 (698). (ABSTRACT TRUNCATED)
1,829 citations
TL;DR: Comprehensive understanding of how HSP90 functions promises not only to provide new avenues for therapeutic intervention, but to shed light on fundamental biological questions.
Abstract: Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that facilitates the maturation of a wide range of proteins (known as clients). Clients are enriched in signal transducers, including kinases and transcription factors. Therefore, HSP90 regulates diverse cellular functions and exerts marked effects on normal biology, disease and evolutionary processes. Recent structural and functional analyses have provided new insights on the transcriptional and biochemical regulation of HSP90 and the structural dynamics it uses to act on a diverse client repertoire. Comprehensive understanding of how HSP90 functions promises not only to provide new avenues for therapeutic intervention, but to shed light on fundamental biological questions.
1,633 citations
"Structure, Function and Regulation ..." refers background in this paper
...To date, more than 20 co‐chaper‐ ones have been identified.([1,31]) They regulate the function of Hsp90 in different ways such as inhibition and activation of the ATPase of Hsp90 as well as recruitment of specific client...
[...]
...Heat shock protein 90 (Hsp90), one of the most abundant and conserved molecular chaperones, is essential in eukaryotic cells.([1,2]) Different from other well‐known mo‐ lecular chaperone like Hsp70 and GroEL/ES, Hsp90 is not required for de novo folding of most proteins but facilitates the final maturation of a selected clientele of proteins....
[...]
...Hsp90—DISEASES As one of themost abundant proteins in the cell, Hsp90 is known to counter different types of stresses (Borkovich et al. 1989; Taipale et al. 2010; Schopf et al. 2017)....
[...]
TL;DR: This purified system of five purified proteins should facilitate understanding of how eukaryotlc hsp70 and hsp90 work together as essential components of a process that alters the conformations of substrate proteins to states that respond in signal transduction.
Abstract: Nearly 100 proteins are known to be regulated by hsp90. Most of these substrates or "client proteins" are involved in signal transduction, and they are brought into complex with hsp90 by a multiprotein hsp90/hsp70-based chaperone machinery. In addition to binding substrate proteins at the chaperone site(s), hsp90 binds cofactors at other sites that are part of the heterocomplex assembly machinery as well as immunophilins that connect assembled substrate*hsp90 complexes to protein-trafficking systems. In the 5 years since we last reviewed this subject, much has been learned about hsp90 structure, nucleotide-binding, and cochaperone interactions; the most important concept is that ATP hydrolysis by an intrinsic ATPase activity results in a conformational change in hsp90 that is required to induce conformational change in a substrate protein. The conformational change induced in steroid receptors is an opening of the steroid-binding cleft so that it can be accessed by steroid. We have now developed a minimal system of five purified proteins-hsp90, hsp70, Hop, hsp40, and p23- that assembles stable receptor*hsp90 heterocomplexes. An hsp90*Hop*hsp70*hsp40 complex opens the cleft in an ATP-dependent process to produce a receptor*hsp90 heterocomplex with hsp90 in its ATP-bound conformation, and p23 then interacts with the hsp90 to stabilize the complex. Stepwise assembly experiments have shown that hsp70 and hsp40 first interact with the receptor in an ATP-dependent reaction to produce a receptor*hsp70*hsp40 complex that is "primed" to be activated to the steroid-binding state in a second ATP-dependent step with hsp90, Hop, and p23. Successful use of the five-protein system with other substrates indicates that it can assemble signal protein*hsp90 heterocomplexes whether the substrate is a receptor, a protein kinase, or a transcription factor. This purified system should facilitate understanding of how eukaryotic hsp70 and hsp90 work together as essential components of a process that alters the conformations of substrate proteins to states that respond in signal transduction.
1,463 citations
"Structure, Function and Regulation ..." refers background in this paper
...Early work on Hsp90 mainly focused on the co‐chap‐ erone requirement for the activation of SHRs.([32,33]) The maturation of most SHRs strictly depends on the interaction with Hsp90....
[...]
TL;DR: It is demonstrated that HSP participation in multimolecular complex formation is required for src-mediated transformation and can provide a target for drug modulation.
Abstract: The molecular mechanisms by which oncogenic tyrosine kinases induce cellular transformation are unclear. Herbimycin A, geldanamycin, and certain other benzoquinone ansamycins display an unusual capacity to revert tyrosine kinase-induced oncogenic transformation. As an approach to the study of v-src-mediated transformation, we examined ansamycin action in transformed cells and found that drug-induced reversion could be achieved without direct inhibition of src phosphorylating activity. To identify mechanisms other than kinase inhibition for drug-mediated reversion, we prepared a solid phase-immobilized geldanamycin derivative and affinity precipitated the molecular targets with which the drug interacted. In a range of cell lines, immobilized geldanamycin bound elements of a major class of heat shock protein (HSP90) in a stable and pharmacologically specific manner. Consistent with these binding data, we found that soluble geldanamycin and herbimycin A inhibited specifically the formation of a previously described src-HSP90 heteroprotein complex. A related benzoquinone ansamycin that failed to revert transformed cells did not inhibit the formation of this complex. These results demonstrate that HSP participation in multimolecular complex formation is required for src-mediated transformation and can provide a target for drug modulation.
1,441 citations
"Structure, Function and Regulation ..." refers background in this paper
...Archaea lackHsp90 (Chen et al. 2006), although most bacteria harbor one copy of Hsp90....
[...]
...The most prominent examples of amino-terminal inhibitors are RD and the ansamycin GA (Whitesell et al. 1994; Roe et al. 1999)....
[...]
...Bacterial HtpG hydrolyzes ATP at a rate between that of Hsp82 and Hsp90....
[...]
...TRAP1 shares 50% amino acid similarity with Hsp90β....
[...]
...A largely open issue is why Sti1/Hop harbors three Hsp90/Hsp70-binding sites and how the different TPR and DP modules modulate the interaction with Hsp70 and Hsp90....
[...]