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Toribio R, Navarro A, Castellano MM. HOP stabilizes the HSFA1a and plays a main role in the onset of thermomorphogenesis. PLANT, CELL & ENVIRONMENT 2024. [PMID: 39007522 DOI: 10.1111/pce.15036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 06/26/2024] [Accepted: 07/02/2024] [Indexed: 07/16/2024]
Abstract
Living organisms have the capacity to respond to environmental stimuli, including warm conditions. Upon sensing mild temperature, plants launch a transcriptional response that promotes morphological changes, globally known as thermomorphogenesis. This response is orchestrated by different hormonal networks and by the activity of different transcription factors, including the heat shock factor A1 (HSFA1) family. Members of this family interact with heat shock protein 70 (HSP70) and heat shock protein 90 (HSP90); however, the effect of this binding on the regulation of HSFA1 activity or of the role of cochaperones, such as the HSP70-HSP90 organizing protein (HOP) on HSFA1 regulation, remains unknown. Here, we show that AtHOPs are involved in the folding and stabilization of the HSFA1a and are required for the onset of the transcriptional response associated to thermomorphogenesis. Our results demonstrate that the three members of the AtHOP family bind in vivo to the HSFA1a and that the expression of multiple HSFA1a-responsive-responsive genes is altered in the hop1 hop2 hop3 mutant under warm temperature. Interestingly, HSFA1a is accumulated at lower levels in the hop1 hop2 hop3 mutant, while control levels are recovered in the presence of the proteasome inhibitor MG132 or the synthetic chaperone tauroursodeoxycholic acid (TUDCA). This uncovers the HSFA1a as a client of HOP complexes in plants and reveals the participation of HOPs in HSFA1a stability.
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Affiliation(s)
- René Toribio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria-CSIC (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
| | - Aurora Navarro
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria-CSIC (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
| | - M Mar Castellano
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria-CSIC (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
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Hsp70/Hsp90 Organising Protein (Hop): Coordinating Much More than Chaperones. Subcell Biochem 2023; 101:81-125. [PMID: 36520304 DOI: 10.1007/978-3-031-14740-1_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The Hsp70/Hsp90 organising protein (Hop, also known as stress-inducible protein 1/STI1/STIP1) has received considerable attention for diverse cellular functions in both healthy and diseased states. There is extensive evidence that intracellular Hop is a co-chaperone of the major chaperones Hsp70 and Hsp90, playing an important role in the productive folding of Hsp90 client proteins, although recent evidence suggests that eukaryotic Hop is regulatory within chaperone complexes rather than essential. Consequently, Hop is implicated in many key signalling pathways, including aberrant pathways leading to cancer. Hop is also secreted, and it is now well established that Hop interacts with the prion protein, PrPC, to mediate multiple signalling events. The intracellular and extracellular forms of Hop most likely represent two different isoforms, although the molecular determinants of these divergent functions are yet to be identified. There is also a growing body of research that reports the involvement of Hop in cellular activities that appear independent of either chaperones or PrPC. While the various cellular functions of Hop have been described, its biological function remains elusive. However, recent knockout studies in mammals suggest that Hop has an important role in embryonic development. This review provides a critical overview of the latest molecular, cellular and biological research on Hop, critically evaluating its function in healthy systems and how this function is adapted in diseased states.
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The Hsp70-Hsp90 go-between Hop/Stip1/Sti1 is a proteostatic switch and may be a drug target in cancer and neurodegeneration. Cell Mol Life Sci 2021; 78:7257-7273. [PMID: 34677645 PMCID: PMC8629791 DOI: 10.1007/s00018-021-03962-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 08/24/2021] [Accepted: 09/24/2021] [Indexed: 01/17/2023]
Abstract
The Hsp70 and Hsp90 molecular chaperone systems are critical regulators of protein homeostasis (proteostasis) in eukaryotes under normal and stressed conditions. The Hsp70 and Hsp90 systems physically and functionally interact to ensure cellular proteostasis. Co-chaperones interact with Hsp70 and Hsp90 to regulate and to promote their molecular chaperone functions. Mammalian Hop, also called Stip1, and its budding yeast ortholog Sti1 are eukaryote-specific co-chaperones, which have been thought to be essential for substrate ("client") transfer from Hsp70 to Hsp90. Substrate transfer is facilitated by the ability of Hop to interact simultaneously with Hsp70 and Hsp90 as part of a ternary complex. Intriguingly, in prokaryotes, which lack a Hop ortholog, the Hsp70 and Hsp90 orthologs interact directly. Recent evidence shows that eukaryotic Hsp70 and Hsp90 can also form a prokaryote-like binary chaperone complex in the absence of Hop, and that this binary complex displays enhanced protein folding and anti-aggregation activities. The canonical Hsp70-Hop-Hsp90 ternary chaperone complex is essential for optimal maturation and stability of a small subset of clients, including the glucocorticoid receptor, the tyrosine kinase v-Src, and the 26S/30S proteasome. Whereas many cancers have increased levels of Hop, the levels of Hop decrease in the aging human brain. Since Hop is not essential in all eukaryotic cells and organisms, tuning Hop levels or activity might be beneficial for the treatment of cancer and neurodegeneration.
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Bhattacharya K, Weidenauer L, Luengo TM, Pieters EC, Echeverría PC, Bernasconi L, Wider D, Sadian Y, Koopman MB, Villemin M, Bauer C, Rüdiger SGD, Quadroni M, Picard D. The Hsp70-Hsp90 co-chaperone Hop/Stip1 shifts the proteostatic balance from folding towards degradation. Nat Commun 2020; 11:5975. [PMID: 33239621 PMCID: PMC7688965 DOI: 10.1038/s41467-020-19783-w] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/30/2020] [Indexed: 02/06/2023] Open
Abstract
Hop/Stip1/Sti1 is thought to be essential as a co-chaperone to facilitate substrate transfer between the Hsp70 and Hsp90 molecular chaperones. Despite this proposed key function for protein folding and maturation, it is not essential in a number of eukaryotes and bacteria lack an ortholog. We set out to identify and to characterize its eukaryote-specific function. Human cell lines and the budding yeast with deletions of the Hop/Sti1 gene display reduced proteasome activity due to inefficient capping of the core particle with regulatory particles. Unexpectedly, knock-out cells are more proficient at preventing protein aggregation and at promoting protein refolding. Without the restraint by Hop, a more efficient folding activity of the prokaryote-like Hsp70-Hsp90 complex, which can also be demonstrated in vitro, compensates for the proteasomal defect and ensures the proteostatic equilibrium. Thus, cells may act on the level and/or activity of Hop to shift the proteostatic balance between folding and degradation. Hop, also known as Stip1 or Sti1, facilitates substrate transfer between the Hsp70 and Hsp90 molecular chaperones. Characterization of proteostasis-related pathways in STIP1 knock-out cell lines reveals that in eukaryotes Stip1 modulates the balance between protein folding and degradation.
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Affiliation(s)
- Kaushik Bhattacharya
- Département de Biologie Cellulaire, Université de Genève, Sciences III, 1211, Genève 4, Switzerland
| | - Lorenz Weidenauer
- Protein Analysis Facility, Center for Integrative Genomics, Université de Lausanne, 1015, Lausanne, Switzerland
| | - Tania Morán Luengo
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, 3584, CH, Utrecht, The Netherlands.,Science for Life, Utrecht University, 3584, CH, Utrecht, The Netherlands
| | - Ellis C Pieters
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, 3584, CH, Utrecht, The Netherlands.,Science for Life, Utrecht University, 3584, CH, Utrecht, The Netherlands
| | - Pablo C Echeverría
- Département de Biologie Cellulaire, Université de Genève, Sciences III, 1211, Genève 4, Switzerland.,European Association for the Study of the Liver, 1203, Genève, Switzerland
| | - Lilia Bernasconi
- Département de Biologie Cellulaire, Université de Genève, Sciences III, 1211, Genève 4, Switzerland
| | - Diana Wider
- Département de Biologie Cellulaire, Université de Genève, Sciences III, 1211, Genève 4, Switzerland
| | - Yashar Sadian
- Bioimaging Center, Université de Genève, Sciences II, 1211, Genève 4, Switzerland
| | - Margreet B Koopman
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, 3584, CH, Utrecht, The Netherlands.,Science for Life, Utrecht University, 3584, CH, Utrecht, The Netherlands
| | - Matthieu Villemin
- Département de Biologie Cellulaire, Université de Genève, Sciences III, 1211, Genève 4, Switzerland
| | - Christoph Bauer
- Bioimaging Center, Université de Genève, Sciences II, 1211, Genève 4, Switzerland
| | - Stefan G D Rüdiger
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, 3584, CH, Utrecht, The Netherlands.,Science for Life, Utrecht University, 3584, CH, Utrecht, The Netherlands
| | - Manfredo Quadroni
- Protein Analysis Facility, Center for Integrative Genomics, Université de Lausanne, 1015, Lausanne, Switzerland
| | - Didier Picard
- Département de Biologie Cellulaire, Université de Genève, Sciences III, 1211, Genève 4, Switzerland.
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Darby JF, Vidler LR, Simpson PJ, Al-Lazikani B, Matthews SJ, Sharp SY, Pearl LH, Hoelder S, Workman P. Solution structure of the Hop TPR2A domain and investigation of target druggability by NMR, biochemical and in silico approaches. Sci Rep 2020; 10:16000. [PMID: 32994435 PMCID: PMC7524759 DOI: 10.1038/s41598-020-71969-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/24/2020] [Indexed: 02/08/2023] Open
Abstract
Heat shock protein 90 (Hsp90) is a molecular chaperone that plays an important role in tumour biology by promoting the stabilisation and activity of oncogenic 'client' proteins. Inhibition of Hsp90 by small-molecule drugs, acting via its ATP hydrolysis site, has shown promise as a molecularly targeted cancer therapy. Owing to the importance of Hop and other tetratricopeptide repeat (TPR)-containing cochaperones in regulating Hsp90 activity, the Hsp90-TPR domain interface is an alternative site for inhibitors, which could result in effects distinct from ATP site binders. The TPR binding site of Hsp90 cochaperones includes a shallow, positively charged groove that poses a significant challenge for druggability. Herein, we report the apo, solution-state structure of Hop TPR2A which enables this target for NMR-based screening approaches. We have designed prototype TPR ligands that mimic key native 'carboxylate clamp' interactions between Hsp90 and its TPR cochaperones and show that they block binding between Hop TPR2A and the Hsp90 C-terminal MEEVD peptide. We confirm direct TPR-binding of these ligands by mapping 1H-15N HSQC chemical shift perturbations to our new NMR structure. Our work provides a novel structure, a thorough assessment of druggability and robust screening approaches that may offer a potential route, albeit difficult, to address the chemically challenging nature of the Hop TPR2A target, with relevance to other TPR domain interactors.
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Affiliation(s)
- John F Darby
- Division of Cancer Therapeutics, Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SM2 5NG, UK
| | - Lewis R Vidler
- Division of Cancer Therapeutics, Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SM2 5NG, UK
| | - Peter J Simpson
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
- Bruker UK Ltd, Banner Lane, Coventry, CV4 9GH, UK
| | - Bissan Al-Lazikani
- Division of Cancer Therapeutics, Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SM2 5NG, UK
| | - Stephen J Matthews
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Swee Y Sharp
- Division of Cancer Therapeutics, Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SM2 5NG, UK
| | - Laurence H Pearl
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, UK
- Division of Structural Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, UK
| | - Swen Hoelder
- Division of Cancer Therapeutics, Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SM2 5NG, UK
| | - Paul Workman
- Division of Cancer Therapeutics, Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SM2 5NG, UK.
- Cancer Research UK Convergence Science Centre, The Institute of Cancer Research and Imperial College London, London, UK.
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