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Berisio R, Barra G, Napolitano V, Privitera M, Romano M, Squeglia F, Ruggiero A. HtpG-A Major Virulence Factor and a Promising Vaccine Antigen against Mycobacterium tuberculosis. Biomolecules 2024; 14:471. [PMID: 38672487 PMCID: PMC11048413 DOI: 10.3390/biom14040471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024] Open
Abstract
Tuberculosis (TB) is the leading global cause of death f rom an infectious bacterial agent. Therefore, limiting its epidemic spread is a pressing global health priority. The chaperone-like protein HtpG of M. tuberculosis (Mtb) is a large dimeric and multi-domain protein with a key role in Mtb pathogenesis and promising antigenic properties. This dual role, likely associated with the ability of Heat Shock proteins to act both intra- and extra-cellularly, makes HtpG highly exploitable both for drug and vaccine development. This review aims to gather the latest updates in HtpG structure and biological function, with HtpG operating in conjunction with a large number of chaperone molecules of Mtb. Altogether, these molecules help Mtb recovery after exposure to host-like stress by assisting the whole path of protein folding rescue, from the solubilisation of aggregated proteins to their refolding. Also, we highlight the role of structural biology in the development of safer and more effective subunit antigens. The larger availability of structural information on Mtb antigens and a better understanding of the host immune response to TB infection will aid the acceleration of TB vaccine development.
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Affiliation(s)
- Rita Berisio
- Institute of Biostructures and Bioimaging, IBB, CNR, Via Pietro Castellino 111, I-80131 Naples, Italy; (G.B.); (V.N.); (M.P.); (M.R.); (F.S.)
| | | | | | | | | | | | - Alessia Ruggiero
- Institute of Biostructures and Bioimaging, IBB, CNR, Via Pietro Castellino 111, I-80131 Naples, Italy; (G.B.); (V.N.); (M.P.); (M.R.); (F.S.)
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2
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Rydzy M, Kolesiński P, Szczepaniak A, Grzyb J. DnaK and DnaJ proteins from Hsp70/40 family are involved in Rubisco biosynthesis in Synechocystis sp. PCC6803 and sustain the enzyme assembly in a heterologous system. BMC PLANT BIOLOGY 2023; 23:109. [PMID: 36814186 PMCID: PMC9948308 DOI: 10.1186/s12870-023-04121-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 02/14/2023] [Indexed: 06/01/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the first step of carbon fixation performed by photosynthetic organisms. Form I of this enzyme found in plants and cyanobacteria is composed of eight large (RbcL) and eight small (RbcS) subunits. To form a functional enzyme, Rubisco subunits need to be properly folded, with the assistance of cellular chaperone machinery, and consecutively assembled in a strictly orchestrated manner, with the help of multiple auxiliary factors. In recent years, multiple Rubisco assembly chaperones and their function in enzyme biogenesis have been extensively characterized. Little is known about the potential specialized factors involved in Rubisco subunits folding at the pre-chaperonin stage, yet this knowledge is greatly needed for the fast and efficient testing of new Rubisco variants.Synechococcus sp. PCC 6803 Rubisco shows limited solubility and a lack of assembly in the Escherichia coli expression system. In this study, we aim to identify which additional chaperones are necessary and sufficient in sustaining the heterologous assembly of native Rubisco. Our findings prove that upon the introduction of Synechocystis DnaK2 to the E. coli system, RbcL is produced in soluble form. The addition of specific DnaJ (Sll1384) enhances this effect. We explain these combined effects based on binding constancies, measured for particular partners in vitro, as well as our analysis of the putative tertiary structure of the proteins. Our results have potential implications for Rubisco engineering.
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Affiliation(s)
- Małgorzata Rydzy
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, Wrocław, Poland
| | - Piotr Kolesiński
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, Wrocław, Poland
| | - Andrzej Szczepaniak
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, Wrocław, Poland
| | - Joanna Grzyb
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14a, Wrocław, Poland.
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Nordquist EB, Clerico EM, Chen J, Gierasch LM. Computationally-Aided Modeling of Hsp70-Client Interactions: Past, Present, and Future. J Phys Chem B 2022; 126:6780-6791. [PMID: 36040440 PMCID: PMC10309085 DOI: 10.1021/acs.jpcb.2c03806] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hsp70 molecular chaperones play central roles in maintaining a healthy cellular proteome. Hsp70s function by binding to short peptide sequences in incompletely folded client proteins, thus preventing them from misfolding and/or aggregating, and in many cases holding them in a state that is competent for subsequent processes like translocation across membranes. There is considerable interest in predicting the sites where Hsp70s may bind their clients, as the ability to do so sheds light on the cellular functions of the chaperone. In addition, the capacity of the Hsp70 chaperone family to bind to a broad array of clients and to identify accessible sequences that enable discrimination of those that are folded from those that are not fully folded, which is essential to their cellular roles, is a fascinating puzzle in molecular recognition. In this article we discuss efforts to harness computational modeling with input from experimental data to develop a predictive understanding of the promiscuous yet selective binding of Hsp70 molecular chaperones to accessible sequences within their client proteins. We trace how an increasing understanding of the complexities of Hsp70-client interactions has led computational modeling to new underlying assumptions and design features. We describe the trend from purely data-driven analysis toward increased reliance on physics-based modeling that deeply integrates structural information and sequence-based functional data with physics-based binding energies. Notably, new experimental insights are adding to our understanding of the molecular origins of "selective promiscuity" in substrate binding by Hsp70 chaperones and challenging the underlying assumptions and design used in earlier predictive models. Taking the new experimental findings together with exciting progress in computational modeling of protein structures leads us to foresee a bright future for a predictive understanding of selective-yet-promiscuous binding exploited by Hsp70 molecular chaperones; the resulting new insights will also apply to substrate binding by other chaperones and by signaling proteins.
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Affiliation(s)
- Erik B. Nordquist
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts, 01003, United States
| | - Eugenia M. Clerico
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts, 01003, United States
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts, 01003, United States
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts, 01003, United States
| | - Lila M. Gierasch
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts, 01003, United States
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts, 01003, United States
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4
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Amankwah YS, Collins P, Fleifil Y, Unruh E, Ruiz Márquez KJ, Vitou K, Kravats AN. Grp94 works upstream of BiP in protein remodeling under heat stress. J Mol Biol 2022; 434:167762. [PMID: 35905823 DOI: 10.1016/j.jmb.2022.167762] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 06/28/2022] [Accepted: 07/21/2022] [Indexed: 10/16/2022]
Abstract
Hsp90 and Hsp70 are highly conserved molecular chaperones that promote the proper folding and activation of substrate proteins that are often referred to as clients. The two chaperones functionally collaborate to fold specific clients in an ATP-dependent manner. In eukaryotic cytosol, initial client folding is done by Hsp70 and its co-chaperones, followed by a direct transfer of client refolding intermediates to Hsp90 for final client processing. However, the mechanistic details of collaboration of organelle specific Hsp70 and Hsp90 are lacking. This work investigates the collaboration of the endoplasmic reticulum (ER) Hsp70 and Hsp90, BiP and Grp94 respectively, in protein remodeling using in vitro refolding assays. We show that under milder denaturation conditions, BiP collaborates with its co-chaperones to refold misfolded proteins in an ATP-dependent manner. Grp94 does not play a major role in this refolding reaction. However, under stronger denaturation conditions that favor aggregation, Grp94 works in an ATP-independent manner to bind and hold misfolded clients in a folding competent state for subsequent remodeling by the BiP system. We also show that the collaboration of Grp94 and BiP is not simply a reversal of the eukaryotic refolding mechanism since a direct interaction of Grp94 and BiP is not required for client transfer. Instead, ATP binding but not hydrolysis by Grp94 facilitates the release of the bound client, which is then picked up by the BiP system for subsequent refolding in a Grp94-independent manner.
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Affiliation(s)
- Yaa S Amankwah
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056
| | - Preston Collins
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056
| | - Yasmeen Fleifil
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056
| | - Erin Unruh
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056
| | | | - Katherine Vitou
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056
| | - Andrea N Kravats
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056.
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Friedlander JE, Shen N, Zeng A, Korm S, Feng H. Failure to Guard: Mitochondrial Protein Quality Control in Cancer. Int J Mol Sci 2021; 22:ijms22158306. [PMID: 34361072 PMCID: PMC8348654 DOI: 10.3390/ijms22158306] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/20/2021] [Accepted: 07/27/2021] [Indexed: 02/07/2023] Open
Abstract
Mitochondria are energetic and dynamic organelles with a crucial role in bioenergetics, metabolism, and signaling. Mitochondrial proteins, encoded by both nuclear and mitochondrial DNA, must be properly regulated to ensure proteostasis. Mitochondrial protein quality control (MPQC) serves as a critical surveillance system, employing different pathways and regulators as cellular guardians to ensure mitochondrial protein quality and quantity. In this review, we describe key pathways and players in MPQC, such as mitochondrial protein translocation-associated degradation, mitochondrial stress responses, chaperones, and proteases, and how they work together to safeguard mitochondrial health and integrity. Deregulated MPQC leads to proteotoxicity and dysfunctional mitochondria, which contributes to numerous human diseases, including cancer. We discuss how alterations in MPQC components are linked to tumorigenesis, whether they act as drivers, suppressors, or both. Finally, we summarize recent advances that seek to target these alterations for the development of anti-cancer drugs.
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Affiliation(s)
- Joseph E. Friedlander
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
| | - Ning Shen
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
- Department of Medicine, Section of Hematology and Medical Oncology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Aozhuo Zeng
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
| | - Sovannarith Korm
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
| | - Hui Feng
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
- Department of Medicine, Section of Hematology and Medical Oncology, Boston University School of Medicine, Boston, MA 02118, USA
- Correspondence: ; Tel.: +1-617-358-4688; Fax: +1-617-358-1599
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Mouratidis PXE, Ter Haar G. HSP90 inhibition acts synergistically with heat to induce a pro-immunogenic form of cell death in colon cancer cells. Int J Hyperthermia 2021; 38:1443-1456. [PMID: 34612127 DOI: 10.1080/02656736.2021.1983036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 09/03/2021] [Accepted: 09/14/2021] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Sub-ablative heat induces pleiotropic biological effects in cancer cells, activating programmed cell death or survival processes. These processes decide the fate of the heated cell. This study investigates these and assesses whether heat, in combination with HSP90 inhibition, augments cell death and induces a pro-immune phenotype in these cells. METHODS HCT116 and HT29 cells were subjected to thermal doses (TID) of 60 and 120CEM43 using a PCR thermal cycler. HSP90 was inhibited with NVP-AUY922. Viability was assessed using the MTT assay. Cellular ATP and HSP70 release were assessed using ATP and Enzyme-linked Immunosorbent assays, respectively. Flow cytometry and immunoblotting were used to study the regulation of biomarkers associated with the heat shock response, the cell cycle, and immunogenic and programmed cell death. RESULTS Exposure of HCT116 and HT29 cells to TIDs of 60 and 120CEM43 decreased their viability. In addition, treatment with 120CEM43 increased intracellular HSP70 and the percentage of HCT116/HT29 cells in the G2/M cell cycle phase, ATP release and Calreticulin/HSP70/HSP90 exposure in the plasma membrane, while downregulating CD47 compared to sham-exposed cells. When combined with NVP-AUY922, treatment of HCT116/HT29 cells with 120CEM43 resulted in a synergistic decrease of cell viability associated with the induction of apoptosis. Also, the combined treatments increased Calreticulin exposure, CD47 downregulation, and HSP70 release compared to the sham-exposed cells. CONCLUSION Sub-ablative heating can act synergistically with the clinically relevant HSP90 inhibitor NVP-AUY922 to induce a pro-immunogenic form of cell death in colon cancer cells.
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Affiliation(s)
- Petros X E Mouratidis
- Joint Department of Physics, Division of Radiotherapy and Imaging, The Institute of Cancer Research: Royal Marsden Hospital, Sutton, London, UK
| | - Gail Ter Haar
- Joint Department of Physics, Division of Radiotherapy and Imaging, The Institute of Cancer Research: Royal Marsden Hospital, Sutton, London, UK
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Harnagel A, Lopez Quezada L, Park SW, Baranowski C, Kieser K, Jiang X, Roberts J, Vaubourgeix J, Yang A, Nelson B, Fay A, Rubin E, Ehrt S, Nathan C, Lupoli TJ. Nonredundant functions of Mycobacterium tuberculosis chaperones promote survival under stress. Mol Microbiol 2020; 115:272-289. [PMID: 32996193 DOI: 10.1111/mmi.14615] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 12/12/2022]
Abstract
Bacterial chaperones ClpB and DnaK, homologs of the respective eukaryotic heat shock proteins Hsp104 and Hsp70, are essential in the reactivation of toxic protein aggregates that occur during translation or periods of stress. In the pathogen Mycobacterium tuberculosis (Mtb), the protective effect of chaperones extends to survival in the presence of host stresses, such as protein-damaging oxidants. However, we lack a full understanding of the interplay of Hsps and other stress response genes in mycobacteria. Here, we employ genome-wide transposon mutagenesis to identify the genes that support clpB function in Mtb. In addition to validating the role of ClpB in Mtb's response to oxidants, we show that HtpG, a homolog of Hsp90, plays a distinct role from ClpB in the proteotoxic stress response. While loss of neither clpB nor htpG is lethal to the cell, loss of both through genetic depletion or small molecule inhibition impairs recovery after exposure to host-like stresses, especially reactive nitrogen species. Moreover, defects in cells lacking clpB can be complemented by overexpression of other chaperones, demonstrating that Mtb's stress response network depends upon finely tuned chaperone expression levels. These results suggest that inhibition of multiple chaperones could work in concert with host immunity to disable Mtb.
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Affiliation(s)
- Alexa Harnagel
- Department of Chemistry, New York University, New York, NY, USA
| | - Landys Lopez Quezada
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Sae Woong Park
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Catherine Baranowski
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Karen Kieser
- Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Xiuju Jiang
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Julia Roberts
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Julien Vaubourgeix
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Amy Yang
- Department of Chemistry, New York University, New York, NY, USA
| | - Brock Nelson
- Department of Chemistry, New York University, New York, NY, USA
| | - Allison Fay
- Immunology Program, Sloan Kettering Institute, New York, NY, USA
| | - Eric Rubin
- Immunology Program, Sloan Kettering Institute, New York, NY, USA
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Carl Nathan
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Tania J Lupoli
- Department of Chemistry, New York University, New York, NY, USA.,Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
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Yu CH, Chen Y, Desjardins CA, Tenor JL, Toffaletti DL, Giamberardino C, Litvintseva A, Perfect JR, Cuomo CA. Landscape of gene expression variation of natural isolates of Cryptococcus neoformans in response to biologically relevant stresses. Microb Genom 2020; 6. [PMID: 31860441 PMCID: PMC7067042 DOI: 10.1099/mgen.0.000319] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen that at its peak epidemic levels caused an estimated million cases of cryptococcal meningitis per year worldwide. This species can grow in diverse environmental (trees, soil and bird excreta) and host niches (intracellular microenvironments of phagocytes and free-living in host tissues). The genetic basic for adaptation to these different conditions is not well characterized, as most experimental work has relied on a single reference strain of C. neoformans. To identify genes important for yeast infection and disease progression, we profiled the gene expression of seven C. neoformans isolates grown in five representative in vitro environmental and in vivo conditions. We characterized gene expression differences using RNA-Seq (RNA sequencing), comparing clinical and environmental isolates from two of the major lineages of this species, VNI and VNBI. These comparisons highlighted genes showing lineage-specific expression that are enriched in subtelomeric regions and in lineage-specific gene clusters. By contrast, we find few expression differences between clinical and environmental isolates from the same lineage. Gene expression specific to in vivo stages reflects available nutrients and stresses, with an increase in fungal metabolism within macrophages, and an induction of ribosomal and heat-shock gene expression within the subarachnoid space. This study provides the widest view to date of the transcriptome variation of C. neoformans across natural isolates, and provides insights into genes important for in vitro and in vivo growth stages.
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Affiliation(s)
- Chen-Hsin Yu
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Yuan Chen
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | | | - Jennifer L Tenor
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Dena L Toffaletti
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Charles Giamberardino
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Anastasia Litvintseva
- Mycotic Diseases Branch, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - John R Perfect
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
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Abildgaard AB, Gersing SK, Larsen-Ledet S, Nielsen SV, Stein A, Lindorff-Larsen K, Hartmann-Petersen R. Co-Chaperones in Targeting and Delivery of Misfolded Proteins to the 26S Proteasome. Biomolecules 2020; 10:E1141. [PMID: 32759676 PMCID: PMC7463752 DOI: 10.3390/biom10081141] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis (proteostasis) is essential for the cell and is maintained by a highly conserved protein quality control (PQC) system, which triages newly synthesized, mislocalized and misfolded proteins. The ubiquitin-proteasome system (UPS), molecular chaperones, and co-chaperones are vital PQC elements that work together to facilitate degradation of misfolded and toxic protein species through the 26S proteasome. However, the underlying mechanisms are complex and remain partly unclear. Here, we provide an overview of the current knowledge on the co-chaperones that directly take part in targeting and delivery of PQC substrates for degradation. While J-domain proteins (JDPs) target substrates for the heat shock protein 70 (HSP70) chaperones, nucleotide-exchange factors (NEFs) deliver HSP70-bound substrates to the proteasome. So far, three NEFs have been established in proteasomal delivery: HSP110 and the ubiquitin-like (UBL) domain proteins BAG-1 and BAG-6, the latter acting as a chaperone itself and carrying its substrates directly to the proteasome. A better understanding of the individual delivery pathways will improve our ability to regulate the triage, and thus regulate the fate of aberrant proteins involved in cell stress and disease, examples of which are given throughout the review.
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Affiliation(s)
- Amanda B. Abildgaard
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sarah K. Gersing
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sven Larsen-Ledet
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sofie V. Nielsen
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (S.V.N.); (A.S.)
| | - Amelie Stein
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (S.V.N.); (A.S.)
| | - Kresten Lindorff-Larsen
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Rasmus Hartmann-Petersen
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
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Miura K, Matsuki W, Ogura A, Takao KI, Simizu S. Identification of vibsanin A analog as a novel HSP90 inhibitor. Bioorg Med Chem 2020; 28:115253. [DOI: 10.1016/j.bmc.2019.115253] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 10/25/2022]
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11
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Garbuz DG, Sverchinsky D, Davletshin A, Margulis BA, Mitkevich V, Kulikov AM, Evgen'ev MB. The molecular chaperone Hsp70 from the thermotolerant Diptera species differs from the Drosophila paralog in its thermostability and higher refolding capacity at extreme temperatures. Cell Stress Chaperones 2019; 24:1163-1173. [PMID: 31664698 PMCID: PMC6882968 DOI: 10.1007/s12192-019-01038-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/22/2019] [Accepted: 09/26/2019] [Indexed: 12/17/2022] Open
Abstract
Previously, we demonstrated that species of the Stratiomyidae family exhibit higher tolerance to thermal stress in comparison with that of many representatives of Diptera, including Drosophila species. We hypothesized that species of this group inherited the specific structures of their chaperones from an ancestor of the Stratiomyidae family, and this enabled the descendants to colonize various extreme habitats. To explore this possibility, we cloned and expressed in Escherichia coli copies of the Hsp70 genes from Stratiomys singularior, a typical eurythermal species, and Drosophila melanogaster, for comparison. To investigate the thermal sensitivity of the chaperone function of the inducible 70-kDa heat shock proteins from these species, we used an in vitro refolding luciferase assay. We demonstrated that under conditions of elevated temperature, S. singularior Hsp70 exhibited higher reactivation activity in comparison with D. melanogaster Hsp70 and even human Hsp70. Similarly, S. singularior Hsp70 was significantly more thermostable and showed in vitro refolding activity after preheatment at higher temperatures than D. melanogaster paralog. Thermally induced unfolding experiments using differential scanning calorimetry indicated that Hsp70 from both Diptera species is formed by two domains with different thermal stabilities and that the ATP-binding domain of S. singularior is stable at temperatures 4 degrees higher than that of the D. melanogaster paralog. To the best of our knowledge, this study represents the first report that provides direct experimental data indicating that the evolutionary history of a species may result in adaptive changes in the structures of chaperones to enable them to elicit protective functions at extreme environments.
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Affiliation(s)
- David G Garbuz
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow, Russia, 119991
| | - Dmitry Sverchinsky
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia, 194064
| | - Artem Davletshin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow, Russia, 119991
| | - Boris A Margulis
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia, 194064
| | - Vladimir Mitkevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow, Russia, 119991
| | - Aleksei M Kulikov
- Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia, 119991
| | - Michael B Evgen'ev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow, Russia, 119991.
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12
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Wu H, Dyson HJ. Aggregation of zinc-free p53 is inhibited by Hsp90 but not other chaperones. Protein Sci 2019; 28:2020-2023. [PMID: 31503385 DOI: 10.1002/pro.3726] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/04/2019] [Accepted: 09/07/2019] [Indexed: 11/09/2022]
Abstract
The structured DNA-binding domain (DBD) of p53 is a well-known client protein of the chaperone Hsp90. The p53 DBD contains a single zinc ion, coordinated by the side chains of Cys176, His179, Cys238, and Cys242; zinc coordination plays a structural role to stabilize the DBD and is required for its DNA binding. The ambiguous nature of the p53-Hsp90 interaction, together with the stabilizing role of the zinc in the structure of the DBD, prompted us to examine the interaction of Hsp90 with zinc-free p53 DBD. NMR spectroscopy and native gel electrophoresis did not show any apparent preference for the interaction of the destabilized zinc-free form of p53 DBD with Hsp90. Intriguingly, however, at lower protein concentrations, closer to physiological concentrations, the addition of Hsp90, but not other chaperones such as Hsp70, Hsp40, p23, and HOP, appears to slow or prevent the aggregation of zinc-free p53 DBD. This result suggests that part of the function of the Hsp90-p53 interaction in the cell may be to stabilize the apoprotein in the absence of zinc.
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Affiliation(s)
- Huiwen Wu
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, California
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13
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Moreno DF, Jenkins K, Morlot S, Charvin G, Csikasz-Nagy A, Aldea M. Proteostasis collapse, a hallmark of aging, hinders the chaperone-Start network and arrests cells in G1. eLife 2019; 8:48240. [PMID: 31518229 PMCID: PMC6744273 DOI: 10.7554/elife.48240] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 09/05/2019] [Indexed: 12/26/2022] Open
Abstract
Loss of proteostasis and cellular senescence are key hallmarks of aging, but direct cause-effect relationships are not well understood. We show that most yeast cells arrest in G1 before death with low nuclear levels of Cln3, a key G1 cyclin extremely sensitive to chaperone status. Chaperone availability is seriously compromised in aged cells, and the G1 arrest coincides with massive aggregation of a metastable chaperone-activity reporter. Moreover, G1-cyclin overexpression increases lifespan in a chaperone-dependent manner. As a key prediction of a model integrating autocatalytic protein aggregation and a minimal Start network, enforced protein aggregation causes a severe reduction in lifespan, an effect that is greatly alleviated by increased expression of specific chaperones or cyclin Cln3. Overall, our data show that proteostasis breakdown, by compromising chaperone activity and G1-cyclin function, causes an irreversible arrest in G1, configuring a molecular pathway postulating proteostasis decay as a key contributing effector of cell senescence.
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Affiliation(s)
- David F Moreno
- Molecular Biology Institute of Barcelona (IBMB), CSIC, Barcelona, Spain
| | - Kirsten Jenkins
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,Institute of Mathematical and Molecular Biomedicine, King's College London, London, United Kingdom
| | - Sandrine Morlot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Strasbourg, France.,Université de Strasbourg, Illkirch, France
| | - Gilles Charvin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Strasbourg, France.,Université de Strasbourg, Illkirch, France
| | - Attila Csikasz-Nagy
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,Institute of Mathematical and Molecular Biomedicine, King's College London, London, United Kingdom.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Martí Aldea
- Molecular Biology Institute of Barcelona (IBMB), CSIC, Barcelona, Spain.,Department of Basic Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
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14
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Hsp70 molecular chaperones: multifunctional allosteric holding and unfolding machines. Biochem J 2019; 476:1653-1677. [PMID: 31201219 DOI: 10.1042/bcj20170380] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/17/2019] [Accepted: 05/21/2019] [Indexed: 12/20/2022]
Abstract
The Hsp70 family of chaperones works with its co-chaperones, the nucleotide exchange factors and J-domain proteins, to facilitate a multitude of cellular functions. Central players in protein homeostasis, these jacks-of-many-trades are utilized in a variety of ways because of their ability to bind with selective promiscuity to regions of their client proteins that are exposed when the client is unfolded, either fully or partially, or visits a conformational state that exposes the binding region in a regulated manner. The key to Hsp70 functions is that their substrate binding is transient and allosterically cycles in a nucleotide-dependent fashion between high- and low-affinity states. In the past few years, structural insights into the molecular mechanism of this allosterically regulated binding have emerged and provided deep insight into the deceptively simple Hsp70 molecular machine that is so widely harnessed by nature for diverse cellular functions. In this review, these structural insights are discussed to give a picture of the current understanding of how Hsp70 chaperones work.
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15
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Sun M, Kotler JLM, Liu S, Street TO. The endoplasmic reticulum (ER) chaperones BiP and Grp94 selectively associate when BiP is in the ADP conformation. J Biol Chem 2019; 294:6387-6396. [PMID: 30787103 DOI: 10.1074/jbc.ra118.007050] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 02/09/2019] [Indexed: 11/06/2022] Open
Abstract
Hsp70 and Hsp90 chaperones are critical for protein quality control in the cytosol, whereas organelle-specific Hsp70/Hsp90 paralogs provide similar protection for mitochondria and the endoplasmic reticulum (ER). Cytosolic Hsp70/Hsp90 can operate sequentially with Hsp90 selectively associating with Hsp70 after Hsp70 is bound to a client protein. This observation has long suggested that Hsp90 could have a preference for interacting with clients at their later stages of folding. However, recent work has shown that cytosolic Hsp70/Hsp90 can directly interact even in the absence of a client, which opens up an alternative possibility that the ordered interactions of Hsp70/Hsp90 with clients could be a consequence of regulated changes in the direct interactions between Hsp70 and Hsp90. However, it is unknown how such regulation could occur mechanistically. Here, we find that the ER Hsp70/Hsp90 (BiP/Grp94) can form a direct complex in the absence of a client. Importantly, the direct interaction between BiP and Grp94 is nucleotide-specific, with BiP and Grp94 having higher affinity under ADP conditions and lower affinity under ATP conditions. We show that this nucleotide-specific association between BiP and Grp94 is largely due to the conformation of BiP. When BiP is in the ATP conformation its substrate-binding domain blocks Grp94; in contrast, Grp94 can readily associate with the ADP conformation of BiP, which represents the client-bound state of BiP. Our observations provide a mechanism for the sequential involvement of BiP and Grp94 in client folding where the conformation of BiP provides the signal for the subsequent recruitment of Grp94.
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Affiliation(s)
- Ming Sun
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453
| | - Judy L M Kotler
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453
| | - Shanshan Liu
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453
| | - Timothy O Street
- From the Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453
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16
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Morán Luengo T, Mayer MP, Rüdiger SGD. The Hsp70-Hsp90 Chaperone Cascade in Protein Folding. Trends Cell Biol 2018; 29:164-177. [PMID: 30502916 DOI: 10.1016/j.tcb.2018.10.004] [Citation(s) in RCA: 151] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/19/2018] [Accepted: 10/24/2018] [Indexed: 12/12/2022]
Abstract
Conserved families of molecular chaperones assist protein folding in the cell. Here we review the conceptual advances on three major folding routes: (i) spontaneous, chaperone-independent folding; (ii) folding assisted by repetitive Hsp70 cycles; and (iii) folding by the Hsp70-Hsp90 cascades. These chaperones prepare their protein clients for folding on their own, without altering their folding path. A particularly interesting role is reserved for Hsp90. The function of Hsp90 in folding is its ancient function downstream of Hsp70, free of cochaperone regulation and present in all kingdoms of life. Eukaryotic signalling networks, however, embrace Hsp90 by a plethora of cochaperones, transforming the profolding machinery to a folding-on-demand factor. We discuss implications for biology and molecular medicine.
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Affiliation(s)
- Tania Morán Luengo
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; Science for Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Stefan G D Rüdiger
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; Science for Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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17
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Mayer MP, Gierasch LM. Recent advances in the structural and mechanistic aspects of Hsp70 molecular chaperones. J Biol Chem 2018; 294:2085-2097. [PMID: 30455352 DOI: 10.1074/jbc.rev118.002810] [Citation(s) in RCA: 169] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hsp70 chaperones are central hubs of the protein quality control network and collaborate with co-chaperones having a J-domain (an ∼70-residue-long helical hairpin with a flexible loop and a conserved His-Pro-Asp motif required for ATP hydrolysis by Hsp70s) and also with nucleotide exchange factors to facilitate many protein-folding processes that (re)establish protein homeostasis. The Hsp70s are highly dynamic nanomachines that modulate the conformation of their substrate polypeptides by transiently binding to short, mostly hydrophobic stretches. This interaction is regulated by an intricate allosteric mechanism. The J-domain co-chaperones target Hsp70 to their polypeptide substrates, and the nucleotide exchange factors regulate the lifetime of the Hsp70-substrate complexes. Significant advances in recent years are beginning to unravel the molecular mechanism of this chaperone machine and how they treat their substrate proteins.
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Affiliation(s)
- Matthias P Mayer
- From the Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, 69120 Heidelberg, Germany and
| | - Lila M Gierasch
- the Departments of Biochemistry and Molecular Biology and.,Chemistry, University of Massachusetts, Amherst, Massachusetts 01003
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18
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Radli M, Rüdiger SGD. Dancing with the Diva: Hsp90-Client Interactions. J Mol Biol 2018; 430:3029-3040. [PMID: 29782836 DOI: 10.1016/j.jmb.2018.05.026] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/13/2018] [Accepted: 05/15/2018] [Indexed: 12/29/2022]
Abstract
The molecular chaperone Hsp90 is involved in the folding, maturation, and degradation of a large number structurally and sequentially unrelated clients, often connected to serious diseases. Elucidating the principles of how Hsp90 recognizes this large variety of substrates is essential for comprehending the mechanism of this chaperone machinery, as well as it is a prerequisite for the design of client specific drugs targeting Hsp90. Here, we discuss the recent progress in understanding the substrate recognition principles of Hsp90 and its implications for the role of Hsp90 in the lifecycle of proteins. Hsp90 acts downstream of the chaperone Hsp70, which exposes its substrate to a short and highly hydrophobic cleft. The subsequently acting Hsp90 has an extended client-binding interface that enables a large number of low-affinity contacts. Structural studies show interaction modes of Hsp90 with the intrinsically disordered Alzheimer's disease-causing protein Tau, the kinase Cdk4 in a partially unfolded state and the folded ligand-binding domain of a steroid receptor. Comparing the features shared by these different proteins provides a picture of the substrate-binding principles of Hsp90.
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Affiliation(s)
- Martina Radli
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands; Science for Life, Utrecht University, Utrecht, The Netherlands
| | - Stefan G D Rüdiger
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands; Science for Life, Utrecht University, Utrecht, The Netherlands.
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19
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Morán Luengo T, Kityk R, Mayer MP, Rüdiger SGD. Hsp90 Breaks the Deadlock of the Hsp70 Chaperone System. Mol Cell 2018; 70:545-552.e9. [PMID: 29706537 DOI: 10.1016/j.molcel.2018.03.028] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/17/2018] [Accepted: 03/23/2018] [Indexed: 10/17/2022]
Abstract
Protein folding in the cell requires ATP-driven chaperone machines such as the conserved Hsp70 and Hsp90. It is enigmatic how these machines fold proteins. Here, we show that Hsp90 takes a key role in protein folding by breaking an Hsp70-inflicted folding block, empowering protein clients to fold on their own. At physiological concentrations, Hsp70 stalls productive folding by binding hydrophobic, core-forming segments. Hsp90 breaks this deadlock and restarts folding. Remarkably, neither Hsp70 nor Hsp90 alters the folding rate despite ensuring high folding yields. In fact, ATP-dependent chaperoning is restricted to the early folding phase. Thus, the Hsp70-Hsp90 cascade does not fold proteins, but instead prepares them for spontaneous, productive folding. This stop-start mechanism is conserved from bacteria to man, assigning also a general function to bacterial Hsp90, HtpG. We speculate that the decreasing hydrophobicity along the Hsp70-Hsp90 cascade may be crucial for enabling spontaneous folding.
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Affiliation(s)
- Tania Morán Luengo
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands; Science for Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Roman Kityk
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
| | - Stefan G D Rüdiger
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands; Science for Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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20
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Khairy Abd M, Abu-Bakr H A. Radiosensitizing Efficacy of Diosmin- Hesperidin Complex Against Ehrlich Solid Carcinoma in Mice, A Potential Role of Histone Deacetylase and Pro-angiogenic Chaperones Targeting. INTERNATIONAL JOURNAL OF CANCER RESEARCH 2017; 13:59-70. [DOI: 10.3923/ijcr.2017.59.70] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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21
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Hristozova N, Tompa P, Kovacs D. A Novel Method for Assessing the Chaperone Activity of Proteins. PLoS One 2016; 11:e0161970. [PMID: 27564234 PMCID: PMC5001627 DOI: 10.1371/journal.pone.0161970] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 08/15/2016] [Indexed: 12/02/2022] Open
Abstract
Protein chaperones are molecular machines which function both during homeostasis and stress conditions in all living organisms. Depending on their specific function, molecular chaperones are involved in a plethora of cellular processes by playing key roles in nascent protein chain folding, transport and quality control. Among stress protein families-molecules expressed during adverse conditions, infection, and diseases-chaperones are highly abundant. Their molecular functions range from stabilizing stress-susceptible molecules and membranes to assisting the refolding of stress-damaged proteins, thereby acting as protective barriers against cellular damage. Here we propose a novel technique to test and measure the capability for protective activity of known and putative chaperones in a semi-high throughput manner on a plate reader. The current state of the art does not allow the in vitro measurements of chaperone activity in a highly parallel manner with high accuracy or high reproducibility, thus we believe that the method we report will be of significant benefit in this direction. The use of this method may lead to a considerable increase in the number of experimentally verified proteins with such functions, and may also allow the dissection of their molecular mechanism for a better understanding of their function.
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Affiliation(s)
- Nevena Hristozova
- Structural Biology Department, Flemish Institute of Biotechnology, Brussels, Belgium
- Structural Biology Department, Free University Brussels, Brussels, Belgium
| | - Peter Tompa
- Structural Biology Department, Flemish Institute of Biotechnology, Brussels, Belgium
- Structural Biology Department, Free University Brussels, Brussels, Belgium
- Institute of Enzymology, Hungarian Academy of Sciences, Budapest, Hungary
| | - Denes Kovacs
- Structural Biology Department, Flemish Institute of Biotechnology, Brussels, Belgium
- Structural Biology Department, Free University Brussels, Brussels, Belgium
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22
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Liu J, Yang H, Bao F, Ao K, Zhang X, Zhang Y, Yang S. IBR5 Modulates Temperature-Dependent, R Protein CHS3-Mediated Defense Responses in Arabidopsis. PLoS Genet 2015; 11:e1005584. [PMID: 26451844 PMCID: PMC4599859 DOI: 10.1371/journal.pgen.1005584] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 09/16/2015] [Indexed: 12/18/2022] Open
Abstract
Plant responses to low temperature are tightly associated with defense responses. We previously characterized the chilling-sensitive mutant chs3-1 resulting from the activation of the Toll and interleukin 1 receptor-nucleotide binding-leucine-rich repeat (TIR-NB-LRR)-type resistance (R) protein harboring a C-terminal LIM (Lin-11, Isl-1 and Mec-3 domains) domain. Here we report the identification of a suppressor of chs3, ibr5-7 (indole-3-butyric acid response 5), which largely suppresses chilling-activated defense responses. IBR5 encodes a putative dual-specificity protein phosphatase. The accumulation of CHS3 protein at chilling temperatures is inhibited by the IBR5 mutation. Moreover, chs3-conferred defense phenotypes were synergistically suppressed by mutations in HSP90 and IBR5. Further analysis showed that IBR5, with holdase activity, physically associates with CHS3, HSP90 and SGT1b (Suppressor of the G2 allele of skp1) to form a complex that protects CHS3. In addition to the positive role of IBR5 in regulating CHS3, IBR5 is also involved in defense responses mediated by R genes, including SNC1 (Suppressor of npr1-1, Constitutive 1), RPS4 (Resistance to P. syringae 4) and RPM1 (Resistance to Pseudomonas syringae pv. maculicola 1). Thus, the results of the present study reveal a role for IBR5 in the regulation of multiple R protein-mediated defense responses. Resistance (R) genes play central roles in recognizing pathogens and triggering plant defense responses. CHS3 encodes a TIR-NB-LRR-type R protein harboring a C-terminal LIM domain. A point mutation in CHS3 activates the defense response under chilling stress. Here we identified and characterized ibr5-7, a mutant that suppresses the chilling-induced defense responses of chs3-1. We observed that the enhanced defense responses and cell death in the chs3-1 mutant are synergistically dependent on IBR5 and HSP90. IBR5 physically interacts with CHS3, forming a complex with SGT1b/ HSP90. Moreover, IBR5 is also involved in the R-gene resistance mediated by SNC1, RPS4 and RPM1. Thus, IBR5 plays key roles in regulating defense responses mediated by multiple R proteins.
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Affiliation(s)
- Jingyan Liu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China
| | - Haibian Yang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China
| | - Fei Bao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China
| | - Kevin Ao
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Xiaoyan Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China
| | - Yuelin Zhang
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shuhua Yang
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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23
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Koay YC, McConnell JR, Wang Y, Kim SJ, Buckton LK, Mansour F, McAlpine SR. Chemically accessible hsp90 inhibitor that does not induce a heat shock response. ACS Med Chem Lett 2014; 5:771-6. [PMID: 25050163 DOI: 10.1021/ml500114p] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/13/2014] [Indexed: 02/01/2023] Open
Abstract
Recent cancer therapies have focused on targeting biology networks through a single regulatory protein. Heat shock protein 90 (hsp90) is an ideal oncogenic target as it regulates over 400 client proteins and cochaperones. However, clinical inhibitors of hsp90 have had limited success; the primary reason being that they induce a heat shock response. We describe the synthesis and biological evaluation of a new hsp90 inhibitor, SM253. The previous generation on which SM253 is based (SM145) has poor overall synthetic yields, low solubility, and micromolar cytotoxicity. By comparison SM253 has relatively high overall yields, good aqueous solubility, and is more cytotoxic than its parent compound. Verification that hsp90 is SM253's target was accomplished using pull-down and protein folding assays. SM253 is superior to both SM145 and the clinical candidate 17-AAG as it decreases proteins related to the heat shock response by 2-fold, versus a 2-4-fold increase observed when cells are treated with 17-AAG.
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Affiliation(s)
- Yen Chin Koay
- The University of New South Wales, Sydney, NSW 2052, Australia
| | | | - Yao Wang
- The University of New South Wales, Sydney, NSW 2052, Australia
| | - Seong Jong Kim
- The University of New South Wales, Sydney, NSW 2052, Australia
| | | | - Flora Mansour
- The University of New South Wales, Sydney, NSW 2052, Australia
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24
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Protein quality control and elimination of protein waste: The role of the ubiquitin–proteasome system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:182-96. [DOI: 10.1016/j.bbamcr.2013.06.031] [Citation(s) in RCA: 292] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/28/2013] [Accepted: 06/29/2013] [Indexed: 01/26/2023]
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25
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Sun S, Xuan F, Ge X, Fu H, Zhu J, Zhang S. Identification of differentially expressed genes in hepatopancreas of oriental river prawn, Macrobrachium nipponense exposed to environmental hypoxia. Gene 2014. [DOI: 10.1016/j.gene.2013.10.036] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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26
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Inhibition of Hsp90 and 70 sensitizes melanoma cells to hyperthermia using ferromagnetic particles with a low Curie temperature. Int J Clin Oncol 2013; 19:722-30. [PMID: 23949287 DOI: 10.1007/s10147-013-0606-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 07/24/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND Heat shock protein (Hsp) 90 is a key regulator of various oncogene products and cell-signaling molecules, while Hsp70 protects against heat-induced apoptosis. We previously described a system in which hyperthermia was produced using thermosensitive ferromagnetic particles (FMPs) with a Curie temperature (T c) of 43 °C to mediate automatic temperature control, and demonstrated its antitumor effect in a mouse melanoma model. In the present study, the antitumor effects of combining Hsp90 inhibitor (17DMAG) and Hsp70 inhibitor (quercetin) with FMP-mediated hyperthermia were examined. METHODS Expressions of Hsp90/70 and Akt were evaluated using Western blotting in vitro. In an in vivo study, melanoma cells were subcutaneously injected into the backs of C57BL/6 mice. FMPs were then injected into the resultant tumors, and the mice were divided into groups treated with quercetin and/or 17DMAG with/without hyperthermia. When exposed to a magnetic field, the temperature of tissues containing FMPs increased and stabilized at the T c. The TUNEL method was used to determine whether hyperthermia induced apoptosis within tumors. RESULTS In the group pretreated with hyperthermia + quercetin + 17DMAG, Akt expression was reduced in vitro, the incidence of apoptosis within tumors was greater, and tumor growth was significantly suppressed 20 days after FMP injection in vivo, compared with other treatment groups. The survival rates among tumor-bearing mice observed for a period of 40 days were significantly higher in the hyperthermia + quercetin + 17DMAG group. CONCLUSION Combining Hsp90/70 inhibition with hyperthermia appears to increase their antitumor effects. Thus, the combination of FMP-mediated, self-regulating hyperthermia with Hsp90/70 inhibition has important implications for cancer treatment.
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27
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Homology modeling, ligand docking and in silico mutagenesis of neurospora Hsp80 (90): insight into intrinsic ATPase activity. J Mol Graph Model 2013; 44:54-69. [DOI: 10.1016/j.jmgm.2013.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 01/28/2013] [Accepted: 02/21/2013] [Indexed: 01/15/2023]
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28
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Wiegant F. Hormesis and Cellular Quality Control: A Possible Explanation for the Molecular Mechanisms that Underlie the Benefits of Mild Stress. Dose Response 2012; 11:413-30. [PMID: 23983668 PMCID: PMC3748852 DOI: 10.2203/dose-response.12-030.wiegant] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
In contrast to the detrimental action of severe stress conditions, the beneficial effects of mild stress, known as hormesis, is increasingly discussed and studied. A variety of applications for hormesis in risk assessment processes, anti-ageing strategies and clinical therapies have been proposed. The molecular mechanisms underlying the phenomenon of hormesis, however, are not yet fully understood. A possible mechanism that has been proposed for hormesis, the homoeostasis overshoot hypothesis, assumes that an overshoot of repair- and self-recovery mechanisms in response to mild damage can be held responsible for the beneficial effects of hormesis. The present paper proposes 'cellular quality control' as a further explanation of the molecular mechanisms underlying the benefits observed after exposure to mild stress. The most important quality control mechanisms are outlined and their known and hypothesised actions in hormesis are discussed. As an example, different aspects of protein quality control will be described in more detail, which includes the reaction of the cell upon stress-induced protein damage and -aggregation. The regulation of Heat Shock Proteins and components from the ubiquitin proteasome system as part of cellular quality control is described in relation to its beneficial role in hormesis.
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Affiliation(s)
- F.A.C. Wiegant
- University College Utrecht, Science Department, Utrecht University, and Faculty of Science; Department of Biology, Institute of Education, Utrecht University
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Cassel JA, Ilyin S, McDonnell ME, Reitz AB. Novel inhibitors of heat shock protein Hsp70-mediated luciferase refolding that bind to DnaJ. Bioorg Med Chem 2012; 20:3609-14. [PMID: 22546203 DOI: 10.1016/j.bmc.2012.03.067] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 03/22/2012] [Accepted: 03/29/2012] [Indexed: 01/07/2023]
Abstract
Inhibitors of both heat shock proteins Hsp90 and Hsp70 have been identified in assays measuring luciferase refolding containing rabbit reticulocyte lysate or purified chaperone components. Here, we report the discovery of a series of phenoxy-N-arylacetamides that disrupt Hsp70-mediated luciferase refolding by binding to DnaJ, the bacterial homolog of human Hsp40. Inhibitor characterization experiments demonstrated negative cooperativity with respect to DnaJ and luciferase concentration, but varying the concentration of ATP had no effect on potency. Thermal shift analysis suggested a direct interaction with DnaJ, but not with Hsp70. These compounds may be useful tools for studying DnaJ/Hsp40 in various cellular processes.
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Affiliation(s)
- Joel A Cassel
- ALS Biopharma, LLC, Pennsylvania Biotechnology Center, 3805 Old Easton Rd, Doylestown, PA 18902, USA.
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Sou SN, Ilieva KM, Polizzi KM. Binding of human BiP to the ER stress transducers IRE1 and PERK requires ATP. Biochem Biophys Res Commun 2012; 420:473-8. [PMID: 22446326 DOI: 10.1016/j.bbrc.2012.03.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 03/06/2012] [Indexed: 12/11/2022]
Abstract
ER stress is activated in a number of important diseases such as diabetes, cancer, and neurodegeneration, but the molecular interactions governing the response are still being elucidated. In the absence of stress, protein complexes exist between the ER-resident chaperone BiP and three transmembrane signalling molecules which are responsible for signal transmission. Previous results suggested that cofactors might participate in these interactions, but the molecular details are not well understood. We coexpressed BiP and the lumenal domains of each of the three ER stress transducers and copurified the complexes in the presence of ATP and ADP in order to better understand how the complex is formed. ATP, but not ADP, was required to isolate the BiP-IRE1 and the BiP-PERK complexes, but the BiP-ATF6 complex was purified in all conditions tested. Based on the results, we hypothesize that in contrast to its mode of binding ATF6 and unfolded proteins, BiP binds to IRE1 and PERK in a different manner.
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Affiliation(s)
- Si Nga Sou
- Centre for Process Systems Engineering, Department of Chemical Engineering and Chemical Technology, Imperial College, London SW7 2AZ, United Kingdom.
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Abstract
TRP channels have emerged as key biological sensors in vision, taste, olfaction, hearing, and touch. Despite their importance, virtually nothing is known about the folding and transport of TRP channels during biosynthesis. Here, we identify XPORT (exit protein of rhodopsin and TRP) as a critical chaperone for TRP and its G protein-coupled receptor (GPCR), rhodopsin (Rh1). XPORT is a resident ER and secretory pathway protein that interacts with TRP and Rh1, as well as with Hsp27 and Hsp90. XPORT promotes the targeting of TRP to the membrane in Drosophila S2 cells, a finding that provides a critical first step toward solving a longstanding problem in the successful heterologous expression of TRP. Mutations in xport result in defective transport of TRP and Rh1, leading to retinal degeneration. Our results identify XPORT as a molecular chaperone and provide a mechanistic link between TRP channels and their GPCRs during biosynthesis and transport.
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Evolution and function of diverse Hsp90 homologs and cochaperone proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:607-13. [PMID: 22008467 DOI: 10.1016/j.bbamcr.2011.09.020] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 09/21/2011] [Accepted: 09/23/2011] [Indexed: 01/02/2023]
Abstract
Members of the Hsp90 molecular chaperone family are found in the cytosol, ER, mitochondria and chloroplasts of eukaryotic cells, as well as in bacteria. These diverse family members cooperate with other proteins, such as the molecular chaperone Hsp70, to mediate protein folding, activation and assembly into multiprotein complexes. All examined Hsp90 homologs exhibit similar ATPase rates and undergo similar conformational changes. One of the key differences is that cytosolic Hsp90 interacts with a large number of cochaperones that regulate the ATPase activity of Hsp90 or have other functions, such as targeting clients to Hsp90. Diverse Hsp90 homologs appear to chaperone different types of client proteins. This difference may reflect either the pool of clients requiring Hsp90 function or the requirement for cochaperones to target clients to Hsp90. This review discusses known functions, similarities and differences between Hsp90 family members and how cochaperones are known to affect these functions. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).
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Fu J, Mares C, Lizcano A, Liu Y, Wickes BL. Insertional mutagenesis combined with an inducible filamentation phenotype reveals a conserved STE50 homologue in Cryptococcus neoformans that is required for monokaryotic fruiting and sexual reproduction. Mol Microbiol 2011; 79:990-1007. [PMID: 21299652 DOI: 10.1111/j.1365-2958.2010.07501.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cryptococcus neoformans typically grows in a yeast-like morphology; however, under specific conditions the fungus can produce hyphae that are either dikaryotic or monokaryotic. In this study, we developed a simple method for inducing robust monokaryotic fruiting and combined the assay with Agrobacterium tumefaciens insertional mutagenesis to screen for hyphal mutants. A C. neoformans homologue of the Saccharomyces cerevisiae STE50 gene was identified and characterized. STE50 was found to be required for sexual reproduction and monokaryotic fruiting. Ste50p has conserved SAM and RA domains, as well as two SH3 domains specific to basidiomycetous Ste50 proteins. Analysis of protein-protein interaction showed that Ste50p can interact with Ste11p and Ste20p, and epistasis experiments placed STE50 between STE20 and STE11. Genetic analysis of the role of STE50 in sexual reproduction showed that it was required for all steps, from response to pheromone to production of hyphae. Analysis of the effect of individual Ste50p domains on sexual reproduction and monokaryotic fruiting revealed domain-specific effects for both processes. This study revealed that the C. neoformans STE50 gene has both conserved and novel functions during sexual reproduction and monokaryotic fruiting, and these functions are domain-dependent.
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Affiliation(s)
- J Fu
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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34
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Arnouk H, Zynda ER, Wang XY, Hylander BL, Manjili MH, Repasky EA, Subjeck JR, Latif Kazim A. Tumour secreted grp170 chaperones full-length protein substrates and induces an adaptive anti-tumour immune response in vivo. Int J Hyperthermia 2011; 26:366-75. [PMID: 20210603 DOI: 10.3109/02656730903485910] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
PURPOSE We employed a grp170-secreting tumour cell system to determine whether tumour cells engineered to secrete grp170 generate an antitumour-specific immune response. Further, we examine the possibility that secreted grp170 can bind to and co-transport out of tumour cells full-length tumour antigens that may play a role in the anti-tumour immune response. MATERIALS AND METHODS Wild type Colon-26 and Colon-26 engineered to secrete grp170 were subcutaneously inoculated into BALB/c mice. Tumour growth was monitored, and variations in immunoregulatory mechanisms were evaluated using immunohistochemistry, lymphocyte depletion, ELISpot assays, and Western blot analysis. RESULTS Immunisation of animals with grp170-secreting tumour cells results in rejection of the tumour by induction of antigen-specific, CD8-dependent immune responses. The secreted grp170 is able to deliver full-length tumour antigens to the tumour microenvironment, thus making them available for uptake by antigen presenting cells (APCs) to initiate tumour-specific immune responses. CONCLUSIONS These data parallel our studies showing that hsp110 or grp170 are able to chaperone full-length proteins, and when complexed with protein antigens and used as vaccines, these complexes elicit immune responses in vivo against the protein antigens. This cell-based approach has the potential to be utilised as a tumour-specific vaccine in tumours of various histological origins.
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Affiliation(s)
- Hilal Arnouk
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA, USA
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35
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Lepock JR. Role of nuclear protein denaturation and aggregation in thermal radiosensitization. Int J Hyperthermia 2009; 20:115-30. [PMID: 15195506 DOI: 10.1080/02656730310001637334] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Hyperthermia at temperatures above 41 degrees C denatures a set of thermolabile cellular proteins located in all parts of the cell. Non-histone nuclear proteins, including those comprising the nuclear matrix, appear to be particularly thermolabile. Heating isolated nuclear matrices of Chinese hamster lung (CHL) V79 cells to 46 degrees C at 1 degree C/min results in approximately 15% denaturation. Protein unfolding during denaturation exposes buried hydrophobic residues, which increases protein-protein interactions and results in the co-aggregation of denatured thermolabile proteins and native, aggregative-sensitive nuclear proteins. This aggregated protein, the majority of which is native, is insoluble and resistant to extraction during isolation of nuclei and is responsible for the increased protein content, usually expressed as an increased protein:DNA ratio, of nuclei isolated from heated cells. A large fraction of the aggregated protein is found to be associated with the nuclear matrix, distributed throughout the fibre network and nucleolus. Three general consequences of nuclear protein denaturation and aggregation of relevance to cellular damage are: (1) protein (enzyme) inactivation, both direct inactivation of thermolabile proteins and indirect inactivation due to co-aggregation; (2) reduced accessibility and altered physical properties of DNA due to masking by aggregated protein; and (3) protein redistribution into and out of the nucleus. Functional impairment of the nucleus appears to be due to one or a combination of these basic mechanisms.
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Affiliation(s)
- J R Lepock
- Department of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada.
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Duerfeldt AS, Brandt GEL, Blagg BSJ. Design, synthesis, and biological evaluation of conformationally constrained cis-amide Hsp90 inhibitors. Org Lett 2009; 11:2353-6. [PMID: 19435295 DOI: 10.1021/ol900783m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Conformationally constrained cis-amide chimeric inhibitors of Hsp90 have been synthesized and evaluated for their Hsp90 inhibitory activity. These new compounds exhibited Hsp90 ATPase inhibition and induced Hsp90-dependent client protein degradation in a dose-dependent manner. Biological data reported herein suggests that amide bond isomerization of geldanamycin derivatives plays an important role in affinity for the heteroprotein complex present in cancer cells.
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Affiliation(s)
- Adam S Duerfeldt
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Malott 4070, Lawrence, Kansas 66045-7562, USA
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37
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Ito A, Saito H, Mitobe K, Minamiya Y, Takahashi N, Maruyama K, Motoyama S, Katayose Y, Ogawa JI. Inhibition of heat shock protein 90 sensitizes melanoma cells to thermosensitive ferromagnetic particle-mediated hyperthermia with low Curie temperature. Cancer Sci 2009; 100:558-64. [PMID: 19154416 PMCID: PMC11159285 DOI: 10.1111/j.1349-7006.2008.01072.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Heat shock protein (Hsp) 90 is a key regulator of a variety of oncogene products and cell-signaling molecules, and the therapeutic benefit of its inhibition in combination with radiation or chemotherapy has been investigated. In addition, hyperthermia has been used for many years to treat various malignant tumors. We previously described a system in which hyperthermia was induced using thermosensitive ferromagnetic particles (FMP) with a Curie temperature (Tc = 43 degrees C) low enough to mediate automatic temperature control, and demonstrated its antitumor effect in a mouse melanoma model. In the present study, we examined the antitumor effects of combining a Hsp90 inhibitor (geldanamycin; GA) with FMP-mediated hyperthermia. In cultured B16 melanoma cells, GA exerted an antitumor effect by increasing the cells' susceptibility to hyperthermia and reducing expression of Akt. In an in vivo study, melanoma cells were subcutaneously injected into the backs of C57BL/6 mice. FMP were then injected into the resultant tumors, and the mice were divided into four groups: group I, no treatment (control); group II, one hyperthermia treatment; group III, GA alone; and group IV, GA with hyperthermia. When exposed to a magnetic field, the temperature of tissues containing FMP increased and stabilized at the Tc. In group IV, complete regression of tumors was observed in five of nine mice (56%), whereas no tumor regression was seen in groups I-III. Our findings suggest that inhibition of Hsp90 with hyperthermia increases its antitumor effect. Thus, the combination of FMP-mediated, self-regulating hyperthermia with Hsp90 inhibition has important implications for the treatment of cancer.
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Affiliation(s)
- Aki Ito
- Department of Surgery, Akita University, Hondo, Akita City, Japan
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38
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Tripp J, Mishra SK, Scharf KD. Functional dissection of the cytosolic chaperone network in tomato mesophyll protoplasts. PLANT, CELL & ENVIRONMENT 2009; 32:123-33. [PMID: 19154229 DOI: 10.1111/j.1365-3040.2008.01902.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The heat stress response is universal to all organisms. Upon elevated temperatures, heat stress transcription factors (Hsfs) are activated to up-regulate the expression of molecular chaperones to protect cells against heat damages. In higher plants, the phenomenon is unusually complex both at the level of Hsfs and heat stress proteins (Hsps). Over-expression of both Hsfs and Hsps and the use of RNA interference for gene knock-down in a transient system in tomato protoplasts allowed us to dissect the in vivo chaperone functions of essential components of thermotolerance, such as the cytoplasmic sHsp, Hsp70 and Hsp100 chaperone families, and the regulation of their expression. The results point to specific functions of the different components in protection from protein denaturation and in refolding of denatured proteins.
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Affiliation(s)
- Joanna Tripp
- J. W. Goethe-University, Molecular Cell Biology of Plants, Biocenter N200, 3OG, Max-von-Laue-Str. 9, D-60438 Frankfurt, Germany
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39
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Jin Y, Awad W, Petrova K, Hendershot LM. Regulated release of ERdj3 from unfolded proteins by BiP. EMBO J 2008; 27:2873-82. [PMID: 18923428 DOI: 10.1038/emboj.2008.207] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Accepted: 09/17/2008] [Indexed: 11/09/2022] Open
Abstract
DnaJ proteins often bind to unfolded substrates and recruit their Hsp70 partners. This induces a conformational change in the Hsp70 that stabilizes its binding to substrate. By some unknown mechanism, the DnaJ protein is released. We examined the requirements for the release of ERdj3, a mammalian ER DnaJ, from substrates and found that BiP promoted the release of ERdj3 only in the presence of ATP. Mutations in ERdj3 or BiP that disrupted their interaction interrupted the release of ERdj3. BiP mutants that were defective in any step of the ATPase cycle were also unable to release ERdj3. These results demonstrate that a functional interaction between ERdj3 and BiP, including both a direct interaction and the ability to stimulate BiP's ATPase activity are required to release ERdj3 from substrate and support a model where ERdj3 must recruit BiP and stimulate its high-affinity association with the substrate through activation of ATP hydrolysis to trigger its own release from substrates. On the basis of similarities among DnaJs and Hsp70s, this is likely to be applicable to other Hsp70-DnaJ pairs.
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Affiliation(s)
- Yi Jin
- Department of Genetics and Tumor Cell Biology, St Jude Children's Research Hospital, Memphis, TN 38105, USA
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40
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Dinkins RD, Majee SM, Nayak NR, Martin D, Xu Q, Belcastro MP, Houtz RL, Beach CM, Downie AB. Changing transcriptional initiation sites and alternative 5'- and 3'-splice site selection of the first intron deploys Arabidopsis protein isoaspartyl methyltransferase2 variants to different subcellular compartments. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:1-13. [PMID: 18318686 DOI: 10.1111/j.1365-313x.2008.03471.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Arabidopsis thaliana (L.) Heynh. possesses two PROTEIN-L-ISOASPARTATE METHYLTRANSFERASE (PIMT) genes encoding enzymes (EC 2.1.1.77) capable of converting uncoded l-isoaspartyl residues, arising spontaneously at l-asparaginyl and l-aspartyl sites in proteins, to l-aspartate. PIMT2 produces at least eight transcripts by using four transcriptional initiation sites (TIS; resulting in three different initiating methionines) and both 5'- and 3'-alternative splice site selection of the first intron. The transcripts produce mature proteins capable of converting l-isoaspartate to l-aspartate in small peptide substrates. PIMT:GFP fusion proteins generated a detectable signal in the nucleus. However, whether the protein was also detectable in the cytoplasm, endo-membrane system, chloroplasts, and/or mitochondria, depended on the transcript from which it was produced. On-blot-methylation of proteins, prior to the completion of germination, indicated that cruciferin subunits contain isoaspartate. The implications of using transcriptional mechanisms to expand a single gene's repertoire to protein variants capable of entry into the cell's various compartments are discussed in light of PIMT's presumed role in repairing the proteome.
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Affiliation(s)
- Randy D Dinkins
- USDA-ARS Forage-Animal Production Research Unit, N220C Agriculture Science Center, North, University of Kentucky, Lexington, KY 40546-0091, USA
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Taylor BF, McNeely SC, Miller HL, States JC. Arsenite-induced mitotic death involves stress response and is independent of tubulin polymerization. Toxicol Appl Pharmacol 2008; 230:235-46. [PMID: 18485433 DOI: 10.1016/j.taap.2008.02.030] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 02/21/2008] [Accepted: 02/25/2008] [Indexed: 10/22/2022]
Abstract
Arsenite, a known mitotic disruptor, causes cell cycle arrest and cell death at anaphase. The mechanism causing mitotic arrest is highly disputed. We compared arsenite to the spindle poisons nocodazole and paclitaxel. Immunofluorescence analysis of alpha-tubulin in interphase cells demonstrated that, while nocodazole and paclitaxel disrupt microtubule polymerization through destabilization and hyperpolymerization, respectively, microtubules in arsenite-treated cells remain comparable to untreated cells even at supra-therapeutic concentrations. Immunofluorescence analysis of alpha-tubulin in mitotic cells showed spindle formation in arsenite- and paclitaxel-treated cells but not in nocodazole-treated cells. Spindle formation in arsenite-treated cells appeared irregular and multi-polar. gamma-tubulin staining showed that cells treated with nocodazole and therapeutic concentrations of paclitaxel contained two centrosomes. In contrast, most arsenite-treated mitotic cells contained more than two centrosomes, similar to centrosome abnormalities induced by heat shock. Of the three drugs tested, only arsenite treatment increased expression of the inducible isoform of heat shock protein 70 (HSP70i). HSP70 and HSP90 proteins are intimately involved in centrosome regulation and mitotic spindle formation. HSP90 inhibitor 17-DMAG sensitized cells to arsenite treatment and increased arsenite-induced centrosome abnormalities. Combined treatment of 17-DMAG and arsenite resulted in a supra-additive effect on viability, mitotic arrest, and centrosome abnormalities. Thus, arsenite-induced abnormal centrosome amplification and subsequent mitotic arrest is independent of effects on tubulin polymerization and may be due to specific stresses that are protected against by HSP90 and HSP70.
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Affiliation(s)
- B Frazier Taylor
- Department of Pharmacology and Toxicology, Center for Environmental Genomics and Integrative Biology, Center for Genetics and Molecular Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
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42
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Leskovar A, Wegele H, Werbeck ND, Buchner J, Reinstein J. The ATPase cycle of the mitochondrial Hsp90 analog Trap1. J Biol Chem 2008; 283:11677-88. [PMID: 18287101 DOI: 10.1074/jbc.m709516200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Hsp90 is an ATP-dependent molecular chaperone whose mechanism is not yet understood in detail. Here, we present the first ATPase cycle for the mitochondrial member of the Hsp90 family called Trap1 (tumor necrosis factor receptor-associated protein 1). Using biochemical, thermodynamic, and rapid kinetic methods we dissected the kinetics of the nucleotide-regulated rearrangements between the open and the closed conformations. Surprisingly, upon ATP binding, Trap1 shifts predominantly to the closed conformation (70%), but, unlike cytosolic Hsp90 from yeast, this process is rather slow at 0.076 s(-1). Because reopening (0.034 s(-1)) is about ten times faster than hydrolysis (k(hyd) = 0.0039 s(-1)), which is the rate-limiting step, Trap1 is not able to commit ATP to hydrolysis. The proposed ATPase cycle was further scrutinized by a global fitting procedure that utilizes all relevant experimental data simultaneously. This analysis corroborates our model of a two-step binding mechanism of ATP followed by irreversible ATP hydrolysis and a one-step product (ADP) release.
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Affiliation(s)
- Adriane Leskovar
- Department of Biomolecular Mechanisms, Max-Planck-Institute for Medical Research, Jahnstrasse 29, Heidelberg 69120, Germany
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43
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Global screening of genes essential for growth in high-pressure and cold environments: searching for basic adaptive strategies using a yeast deletion library. Genetics 2008; 178:851-72. [PMID: 18245339 DOI: 10.1534/genetics.107.083063] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Microorganisms display an optimal temperature and hydrostatic pressure for growth. To establish the molecular basis of piezo- and psychroadaptation, we elucidated global genetic defects that give rise to susceptibility to high pressure and low temperature in Saccharomyces cerevisiae. Here we present 80 genes including 71 genes responsible for high-pressure growth and 56 responsible for low-temperature growth with a significant overlap of 47 genes. Numerous previously known cold-sensitive mutants exhibit marked high-pressure sensitivity. We identified critically important cellular functions: (i) amino acid biosynthesis, (ii) microautophagy and sorting of amino acid permease established by the exit from rapamycin-induced growth arrest/Gap1 sorting in the endosome (EGO/GSE) complex, (iii) mitochondrial functions, (iv) membrane trafficking, (v) actin organization mediated by Drs2-Cdc50, and (vi) transcription regulated by the Ccr4-Not complex. The loss of EGO/GSE complex resulted in a marked defect in amino acid uptake following high-pressure and low-temperature incubation, suggesting its role in surface delivery of amino acid permeases. Microautophagy and mitochondrial functions converge on glutamine homeostasis in the target of rapamycin (TOR) signaling pathway. The localization of actin requires numerous associated proteins to be properly delivered by membrane trafficking. In this study, we offer a novel route to gaining insights into cellular functions and the genetic network from growth properties of deletion mutants under high pressure and low temperature.
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44
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Wisén S, Gestwicki JE. Identification of small molecules that modify the protein folding activity of heat shock protein 70. Anal Biochem 2007; 374:371-7. [PMID: 18191466 DOI: 10.1016/j.ab.2007.12.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Revised: 11/23/2007] [Accepted: 12/07/2007] [Indexed: 10/22/2022]
Abstract
Molecular chaperones, such as heat shock protein 70 (Hsp70) and its bacterial ortholog DnaK, play numerous important roles in protein folding. In vitro, this activity can be observed by incubating purified chaperones with denatured substrates and measuring the recovery of properly folded protein. In an effort to rapidly identify small molecules that modify this folding activity, we modified an existing method for use in 96-well plates. In this assay, denatured firefly luciferase was treated with a mixture of DnaK and prospective chemical modulators. The luminescence of refolded luciferase was used to follow the reaction progress, and counterscreens excluded compounds that target luciferase; thus, hits from these screens modify protein folding via their effects on the function of the chaperone machine. Using this platform, we screened a pilot chemical library and found five new inhibitors of DnaK and one compound that promoted folding. These chemical probes may be useful in studies aimed at understanding the many varied roles of chaperones in cellular protein folding. Moreover, this assay provides the opportunity to rapidly screen for additional compounds that might regulate the folding activity of Hsp70.
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Affiliation(s)
- Susanne Wisén
- Departments of Pathology and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
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45
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Browne CL, Swan JB, Rankin EE, Calvert H, Griffiths S, Tytell M. Extracellular heat shock protein 70 has novel functional effects on sea urchin eggs and coelomocytes. ACTA ACUST UNITED AC 2007; 210:1275-87. [PMID: 17371926 DOI: 10.1242/jeb.02743] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Numerous reports document that the 70 kDa heat shock proteins are not only intracellular proteins but are also present in blood and other extracellular compartments. How they affect cell function from the extracellular space remains unclear. Using two well-characterized cell types from the sea urchin, we show that extracellular mixtures of the constitutive and inducible forms of the 70 kDa heat shock proteins (Hsc70 and Hsp70, respectively) have dramatic effects on initiation of cell division in fertilized eggs and on the clotting reaction of hypotonically stressed coelomocytes. In suspensions of fertilized eggs to which Hsc70 or a 2:3 mixture of Hsc and Hsp70 was added, progression to the first mitotic division was accelerated. Evidence is provided that the extracellular Hsc70 passes into the egg cells in an unconventional manner, being distributed through the cytoplasm, and that it may alter the intracellular signaling cascade initiated by sperm penetration. In coelomocytes that were stimulated by hypotonic shock to mimic injury, the spreading reaction of the clotting response was significantly inhibited when either Hsp70 or Hsc70 was in the medium. These results suggest that the presence of Hsc and/or Hsp70 in the extracellular fluid may promote mitosis of dividing cells and suppress the reactivity of immune system cells.
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Affiliation(s)
- Carole L Browne
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA.
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46
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Taylor DM, Tradewell ML, Minotti S, Durham HD. Characterizing the role of Hsp90 in production of heat shock proteins in motor neurons reveals a suppressive effect of wild-type Hsf1. Cell Stress Chaperones 2007; 12:151-62. [PMID: 17688194 PMCID: PMC1949336 DOI: 10.1379/csc-254r.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Induction of heat shock proteins (Hsps) is under investigation as treatment for neurodegenerative disorders, yet many types of neurons, including motor neurons that degenerate in amyotrophic lateral sclerosis (ALS), have a high threshold for activation of the major transcription factor mediating stress-induced Hsp upregulation, heat shock transcription factor 1 (Hsf1). Hsf1 is tightly regulated by a series of inhibitory checkpoints that include sequestration in multichaperone complexes governed by Hsp90. This study examined the role of multichaperone complexes in governing the heat shock response in motor neurons. Hsp90 inhibitors induced expression of Hsp70 and Hsp40 and transactivation of a human inducible hsp70 promoter-green fluorescent protein (GFP) reporter construct in motor neurons of dissociated spinal cord-dorsal root ganglion (DRG) cultures. On the other hand, overexpression of activator of Hsp90 adenosine triphosphatase ([ATPase 1], Aha1), which should mobilize Hsf1 by accelerating turnover of mature, adenosine triphosphate-(ATP) bound Hsp90 complexes, and death domain-associated protein (Daxx), which in cell lines has been shown to promote transcription of heat shock genes by relieving inhibition exerted by interactions between nuclear Hsp90/multichaperone complexes and trimeric Hsf1, failed to induce Hsps in the absence or presence of heat shock. These results indicate that disruption of multichaperone complexes alone is not sufficient to activate the neuronal heat shock response. Furthermore, in motor neurons, induction of Hsp70 by Hsp90-inhibiting drugs was prevented by overexpression of wild-type Hsfl, contrary to what would be expected for a classical Hsf1-mediated pathway. These results point to additional differences in regulation of hsp genes in neuronal and nonneuronal cells.
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Affiliation(s)
- David M Taylor
- Montreal Neurological Institute, McGill University, 3801 University St., Montreal, Quebec H3A 2B4, Canada
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Galam L, Hadden MK, Ma Z, Ye Q, Yun BG, Blagg BSJ, Matts RL. High-throughput assay for the identification of Hsp90 inhibitors based on Hsp90-dependent refolding of firefly luciferase. Bioorg Med Chem 2007; 15:1939-46. [PMID: 17223347 PMCID: PMC1906718 DOI: 10.1016/j.bmc.2007.01.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 12/20/2006] [Accepted: 01/01/2007] [Indexed: 10/23/2022]
Abstract
Previously, we have demonstrated that the renaturation of heat denatured firefly luciferase is dependent upon the activity of Hsp90 in rabbit reticulocyte lysate. Here, we demonstrate that this assay may identify inhibitors that obstruct the chaperone activity of Hsp90 either by direct binding to its N-terminal or C-terminal nucleotide binding sites or by interference with the ability of the chaperone to switch conformations. The assay was adapted and optimized for high-throughput screening. Greater than 20,000 compounds were screened to demonstrate the feasibility of using this assay on a large scale. The assay was reproducible (av Z-factor=0.62) and identified 120 compounds that inhibited luciferase renaturation by greater than 70% at a concentration of 12.5 microg/mL. IC50 values for twenty compounds with varying structures were determined for inhibition of luciferase refolding and in cell-based assays for Hsp90 inhibition. Several compounds had IC50 values <10 microM and represent a number of new lead structures with the potential for further development and optimization as potent Hsp90 inhibitors.
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Affiliation(s)
- Lakshmi Galam
- Department of Biochemistry and Molecular Biology, NRC 246, Oklahoma State University, Stillwater, Oklahoma, U.S.A. 74078
| | - M. Kyle Hadden
- Department of Medicinal Chemistry, 1251 Wescoe Hall Drive, Malott 4070, The University of Kansas, Lawrence, Kansas, U.S.A. 66045-7563
| | - Zeqiang Ma
- High-Throughput Screening Laboratory, The University of Kansas, 1501 Wakarusa Drive, Lawrence, Kansas, U.S.A. 66047
| | - Qi–Zhuang Ye
- High-Throughput Screening Laboratory, The University of Kansas, 1501 Wakarusa Drive, Lawrence, Kansas, U.S.A. 66047
| | - Bo-Geon Yun
- Department of Biochemistry and Molecular Biology, NRC 246, Oklahoma State University, Stillwater, Oklahoma, U.S.A. 74078
| | - Brian S. J. Blagg
- Department of Medicinal Chemistry, 1251 Wescoe Hall Drive, Malott 4070, The University of Kansas, Lawrence, Kansas, U.S.A. 66045-7563
| | - Robert L. Matts
- Department of Biochemistry and Molecular Biology, NRC 246, Oklahoma State University, Stillwater, Oklahoma, U.S.A. 74078
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Shaner L, Sousa R, Morano KA. Characterization of Hsp70 binding and nucleotide exchange by the yeast Hsp110 chaperone Sse1. Biochemistry 2007; 45:15075-84. [PMID: 17154545 PMCID: PMC2676923 DOI: 10.1021/bi061279k] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
SSE1 and SSE2 encode the essential yeast members of the Hsp70-related Hsp110 molecular chaperone family. Both mammalian Hsp110 and the Sse proteins functionally interact with cognate cytosolic Hsp70s as nucleotide exchange factors. We demonstrate here that Sse1 forms high-affinity (Kd approximately 10-8 M) heterodimeric complexes with both yeast Ssa and mammalian Hsp70 chaperones and that binding of ATP to Sse1 is required for binding to Hsp70s. Sse1.Hsp70 heterodimerization confers resistance to exogenously added protease, indicative of conformational changes in Sse1 resulting in a more compact structure. The nucleotide binding domains of both Sse1/2 and the Hsp70s dictate interaction specificity and are sufficient for mediating heterodimerization with no discernible contribution from the peptide binding domains. In support of a strongly conserved functional interaction between Hsp110 and Hsp70, Sse1 is shown to associate with and promote nucleotide exchange on human Hsp70. Nucleotide exchange activity by Sse1 is physiologically significant, as deletion of both SSE1 and the Ssa ATPase stimulatory protein YDJ1 is synthetically lethal. The Hsp110 family must therefore be considered an essential component of Hsp70 chaperone biology in the eukaryotic cell.
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Affiliation(s)
- Lance Shaner
- Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, TX 77030
| | - Rui Sousa
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900
| | - Kevin A. Morano
- Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, TX 77030
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Bredemeyer AJ, Carrigan PE, Fehniger TA, Smith DF, Ley TJ. Hop cleavage and function in granzyme B-induced apoptosis. J Biol Chem 2006; 281:37130-41. [PMID: 17005566 DOI: 10.1074/jbc.m607969200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Granzyme B (GzmB) is a cytotoxic protease found in the granules of natural killer cells and cytotoxic T lymphocytes. GzmB cleaves multiple intracellular protein substrates, leading to caspase activation, DNA fragmentation, cytoskeletal instability, and rapid induction of target cell apoptosis. However, no known individual substrate is required for GzmB to induce apoptosis. GzmB is therefore thought to initiate multiple cell death pathways simultaneously to ensure the death of target cells. We previously identified Hop (Hsp70/Hsp90-organizing protein) as a GzmB substrate in a proteomic survey (Bredemeyer, A. J., Lewis, R. M., Malone, J. P., Davis, A. E., Gross, J., Townsend, R. R., and Ley, T. J. (2004) Proc. Natl. Acad. Sci. U. S. A. 101, 11785-11790). Hop is a co-chaperone for Hsp70 and Hsp90, which have been implicated in the negative regulation of apoptosis. We therefore hypothesized that Hop may have an anti-apoptotic function that is abolished upon cleavage, lowering the threshold for GzmB-induced apoptosis. Here, we show that Hop was cleaved directly by GzmB in vitro and in cells undergoing GzmB-induced apoptosis. Expression of the two cleavage fragments of Hop did not induce cell death. Although cleavage of Hop by GzmB destroyed Hop function in vitro, both cells overexpressing GzmB-resistant Hop and cells with a 90-95% reduction in Hop levels exhibited unaltered susceptibility to GzmB-induced death. We conclude that Hop per se does not set the threshold for susceptibility to GzmB-induced apoptosis. Although it is possible that Hop may be cleaved by GzmB as an "innocent bystander" during the induction of apoptosis, it may also act to facilitate apoptosis in concert with other GzmB substrates.
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Affiliation(s)
- Andrew J Bredemeyer
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Fayazi Z, Ghosh S, Marion S, Bao X, Shero M, Kazemi-Esfarjani P. A Drosophila ortholog of the human MRJ modulates polyglutamine toxicity and aggregation. Neurobiol Dis 2006; 24:226-44. [PMID: 16934481 DOI: 10.1016/j.nbd.2006.06.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 06/19/2006] [Accepted: 06/28/2006] [Indexed: 01/13/2023] Open
Abstract
In the Drosophila eye, proteins with an expanded polyglutamine (polyQ) tract form nuclear and cytoplasmic inclusions and produce cytotoxicity, demonstrated as loss of eye pigmentation and structural integrity. An EP P-element that suppressed the loss of eye pigmentation was inserted 9.7 kb upstream of dmrj, a gene that encodes an ortholog of a brain-enriched cochaperone, the human MRJ (mammalian relative of DnaJ). Despite the large distance between them, quantitative polymerase chain reaction indicated that the EP could overexpress dmrj. In the retina and other neurons, transgenic dMRJ suppressed polyQ toxicity and colocalized with its inclusions. In the photoreceptors, expression of another suppressor with a J domain, dHDJ1, but not dMRJ, prior to expression of expanded polyQs dramatically promoted cytoplasmic aggregation. However, both proteins increased the level of detergent-soluble, monomeric polyQ-expanded proteins. These findings exemplify the functional similarities and differences between J domain proteins in suppressing polyQ toxicity.
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Affiliation(s)
- Zahra Fayazi
- Department of Physiology and Biophysics, Center for Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214, USA
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