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Sakunthala A, Maji SK. Deciphering the Seed Size-Dependent Cellular Internalization Mechanism for α-Synuclein Fibrils. Biochemistry 2025; 64:377-400. [PMID: 39762762 DOI: 10.1021/acs.biochem.4c00667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2025]
Abstract
Aggregation of α-synuclein (α-Syn) and Lewy body (LB) formation are the key pathological events implicated in Parkinson's disease (PD) that spread in a prion-like manner. However, biophysical and structural characteristics of toxic α-Syn species and molecular events that drive early events in the propagation of α-Syn amyloids in a prion-like manner remain elusive. We used a neuronal cell model to demonstrate the size-dependent native biological activities of α-Syn fibril seeds. Biophysical characterization of the fibril seeds generated by controlled fragmentation indicated that increased fragmentation leads to a reduction in fibril size, correlating directly with the extent of fragmentation events. Although the size-based complexity of amyloid fibrils modulates their biological activities and fibril amplification pathways, it remains unclear how the variability of fibril seed size dictates its specific uptake mechanism into the cells. The present study elucidates the mechanism of α-Syn fibril internalization and how it is regulated by the size of fibril seeds. Further, we demonstrate that size-dependent endocytic pathways (dynamin-dependent clathrin/caveolin-mediated) are more prominent for the differential uptake of short fibril seeds compared to their longer counterparts. This size-dependent preference might contribute to the enhanced uptake and transcellular propagation of short α-Syn fibril seeds in a prion-like manner. Overall, the present study suggests that the physical dimension of α-Syn amyloid fibril seeds significantly influences their cellular uptake and pathological responses in the initiation and progression of PD.
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Affiliation(s)
- Arunima Sakunthala
- Sunita Sanghi Centre of Aging and Neurodegenerative Diseases (SCAN), Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
- Department of Biosciences& Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Samir K Maji
- Sunita Sanghi Centre of Aging and Neurodegenerative Diseases (SCAN), Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
- Department of Biosciences& Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Sakunthala A, Datta D, Navalkar A, Gadhe L, Kadu P, Patel K, Mehra S, Kumar R, Chatterjee D, Devi J, Sengupta K, Padinhateeri R, Maji SK. Direct Demonstration of Seed Size-Dependent α-Synuclein Amyloid Amplification. J Phys Chem Lett 2022; 13:6427-6438. [PMID: 35816132 DOI: 10.1021/acs.jpclett.2c01650] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The size of amyloid seeds is known to modulate their autocatalytic amplification and cellular toxicity. However, the seed size-dependent secondary nucleation mechanism, toxicity, and disease-associated biological processes mediated by α-synuclein (α-Syn) fibrils are largely unknown. Using the cellular model and in vitro reconstitution, we showed that the size of α-Syn fibril seeds dictates not only their cellular internalization and associated cell death but also the distinct mechanisms of fibril amplification pathways involved in the pathological conformational change of α-Syn. Specifically, small fibril seeds showed elongation possibly through monomer addition at the fibril termini, whereas longer fibrils template the fibril amplification by surface-mediated nucleation as demonstrated by super-resolution microscopy. The distinct mechanism of fibril amplification and cellular uptake along with toxicity suggest that breakage of fibrils into seeds of different sizes determines the underlying pathological outcome of synucleinopathies.
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Affiliation(s)
- Arunima Sakunthala
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Debalina Datta
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Ambuja Navalkar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Laxmikant Gadhe
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Pradeep Kadu
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Komal Patel
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Surabhi Mehra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Rakesh Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Debdeep Chatterjee
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Jyoti Devi
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Kundan Sengupta
- Chromosome Biology Lab, Indian Institute of Science Education and Research, Pune 411008, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Samir K Maji
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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3
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Thackray AM, Lam B, McNulty EE, Nalls AV, Mathiason CK, Magadi SS, Jackson WS, Andréoletti O, Marrero-Winkens C, Schätzl H, Bujdoso R. Clearance of variant Creutzfeldt-Jakob disease prions in vivo by the Hsp70 disaggregase system. Brain 2022; 145:3236-3249. [PMID: 35446941 PMCID: PMC9473358 DOI: 10.1093/brain/awac144] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 03/10/2022] [Accepted: 03/30/2022] [Indexed: 11/13/2022] Open
Abstract
The metazoan Hsp70 disaggregase protects neurons from proteotoxicity that arises from the accumulation of misfolded protein aggregates. Hsp70 and its co-chaperones disassemble and extract polypeptides from protein aggregates for refolding or degradation. The effectiveness of the chaperone system decreases with age and leads to accumulation rather than removal of neurotoxic protein aggregates. Therapeutic enhancement of the Hsp70 protein disassembly machinery is proposed to counter late-onset protein misfolding neurodegenerative disease that may arise. In the context of prion disease, it is not known whether stimulation of protein aggregate disassembly paradoxically leads to enhanced formation of seeding competent species of disease-specific proteins and acceleration of neurodegenerative disease. Here we have tested the hypothesis that modulation of Hsp70 disaggregase activity perturbs mammalian prion-induced neurotoxicity and prion seeding activity. To do so we used prion protein (PrP) transgenic Drosophila that authentically replicate mammalian prions. RNASeq identified that Hsp70, DnaJ-1 and Hsp110 gene expression was downregulated in prion-exposed PrP Drosophila. We demonstrated that RNAi knockdown of Hsp110 or DnaJ-1 gene expression in variant Creutzfeldt–Jakob disease prion-exposed human PrP Drosophila enhanced neurotoxicity, whereas overexpression mitigated toxicity. Strikingly, prion seeding activity in variant Creutzfeldt–Jakob disease prion-exposed human PrP Drosophila was ablated or reduced by Hsp110 or DnaJ-1 overexpression, respectively. Similar effects were seen in scrapie prion-exposed ovine PrP Drosophila with modified Hsp110 or DnaJ-1 gene expression. These unique observations show that the metazoan Hsp70 disaggregase facilitates the clearance of mammalian prions and that its enhanced activity is a potential therapeutic strategy for human prion disease.
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Affiliation(s)
- Alana M Thackray
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK
| | - Brian Lam
- Medical Research Council Metabolic Diseases Unit, Wellcome-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Erin E McNulty
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Amy V Nalls
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Candace K Mathiason
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Srivathsa Subramanya Magadi
- Wallenberg Center for Molecular Medicine, Department of Clinical and Experimental Medicine, Linköping University, 581 83 Linköping, Sweden
| | - Walker S Jackson
- Wallenberg Center for Molecular Medicine, Department of Clinical and Experimental Medicine, Linköping University, 581 83 Linköping, Sweden
| | - Olivier Andréoletti
- UMR INRA ENVT 1225 -Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, 31076 Toulouse, France
| | - Cristóbal Marrero-Winkens
- Calgary Prion Research Unit, Faculty of Veterinary Medicine, University of Calgary TRW 2D10, 3280 Hospital Drive NW, Calgary, AB, Canada T2N 4Z6
| | - Hermann Schätzl
- Calgary Prion Research Unit, Faculty of Veterinary Medicine, University of Calgary TRW 2D10, 3280 Hospital Drive NW, Calgary, AB, Canada T2N 4Z6
| | - Raymond Bujdoso
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK
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Tittelmeier J, Sandhof CA, Ries HM, Druffel-Augustin S, Mogk A, Bukau B, Nussbaum-Krammer C. The HSP110/HSP70 disaggregation system generates spreading-competent toxic α-synuclein species. EMBO J 2020; 39:e103954. [PMID: 32449565 PMCID: PMC7327497 DOI: 10.15252/embj.2019103954] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 04/19/2020] [Accepted: 04/23/2020] [Indexed: 12/21/2022] Open
Abstract
The accumulation and prion-like propagation of α-synuclein and other amyloidogenic proteins are associated with devastating neurodegenerative diseases. Metazoan heat shock protein HSP70 and its co-chaperones DNAJB1 and HSP110 constitute a disaggregation machinery that is able to disassemble α-synuclein fibrils in vitro, but its physiological effects on α-synuclein toxicity are unknown. Here, we depleted Caenorhabditis elegans HSP-110 and monitored the consequences on α-synuclein-related pathological phenotypes such as misfolding, intercellular spreading, and toxicity in C. elegans in vivo models. Depletion of HSP-110 impaired HSP70 disaggregation activity, prevented resolubilization of amorphous aggregates, and compromised the overall cellular folding capacity. At the same time, HSP-110 depletion reduced α-synuclein foci formation, cell-to-cell transmission, and toxicity. These data demonstrate that the HSP70 disaggregation activity constitutes a double-edged sword, as it is essential for maintaining cellular proteostasis but also involved in the generation of toxic amyloid-type protein species.
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Affiliation(s)
- Jessica Tittelmeier
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Carl Alexander Sandhof
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Heidrun Maja Ries
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Silke Druffel-Augustin
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Carmen Nussbaum-Krammer
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
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5
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Mazurskyy A, Howitt J. Initiation and Transmission of α-Synuclein Pathology in Parkinson's Disease. Neurochem Res 2019; 44:10.1007/s11064-019-02896-0. [PMID: 31713092 DOI: 10.1007/s11064-019-02896-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/11/2019] [Accepted: 10/18/2019] [Indexed: 02/06/2023]
Abstract
The pathogenesis of Parkinson's disease (PD) involves the accumulation of aggregated forms of α-synuclein in the body. The location for the initiation of misfolded forms of α-synuclein is now a contentious issue, what was once thought to be a disease of the central nervous system (CNS) now appears to involve multiple organs in the body. In particular, the two regions in the body where the nervous system is exposed to the environment, the olfactory bulb and the enteric nervous system, are now thought to play an important role in the initial phase of the disease. Epidemiological studies point to the gastrointestinal tract, including the appendix, as a potential site for the misfolding and transmission of α-synuclein, with the vagus nerve providing a conduit between the gut and brain. A growing body of animal studies also support this pathway, implicating the transmission of pathological α-synuclein from outside the CNS in the development of PD.
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Affiliation(s)
- Alex Mazurskyy
- School of Health Sciences, Swinburne University, Melbourne, Australia
| | - Jason Howitt
- School of Health Sciences, Swinburne University, Melbourne, Australia.
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6
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Serio TR. [PIN+]ing down the mechanism of prion appearance. FEMS Yeast Res 2019; 18:4923032. [PMID: 29718197 PMCID: PMC5889010 DOI: 10.1093/femsyr/foy026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 03/03/2018] [Indexed: 11/13/2022] Open
Abstract
Prions are conformationally flexible proteins capable of adopting a native state and a spectrum of alternative states associated with a change in the function of the protein. These alternative states are prone to assemble into amyloid aggregates, which provide a structure for self-replication and transmission of the underlying conformer and thereby the emergence of a new phenotype. Amyloid appearance is a rare event in vivo, regulated by both the aggregation propensity of prion proteins and their cellular environment. How these forces normally intersect to suppress amyloid appearance and the ways in which these restrictions can be bypassed to create protein-only phenotypes remain poorly understood. The most widely studied and perhaps most experimentally tractable system to explore the mechanisms regulating amyloid appearance is the [PIN+] prion of Saccharomyces cerevisiae. [PIN+] is required for the appearance of the amyloid state for both native yeast proteins and for human proteins expressed in yeast. These observations suggest that [PIN+] facilitates the bypass of amyloid regulatory mechanisms by other proteins in vivo. Several models of prion appearance are compatible with current observations, highlighting the complexity of the process and the questions that must be resolved to gain greater insight into the mechanisms regulating these events.
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Affiliation(s)
- Tricia R Serio
- The University of Massachusetts-Amherst, Department of Biochemistry and Molecular Biology, 240 Thatcher Rd, N360, Amherst, MA 01003, USA
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7
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Overexpression of the essential Sis1 chaperone reduces TDP-43 effects on toxicity and proteolysis. PLoS Genet 2017; 13:e1006805. [PMID: 28531192 PMCID: PMC5460882 DOI: 10.1371/journal.pgen.1006805] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 06/06/2017] [Accepted: 05/05/2017] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by selective loss of motor neurons with inclusions frequently containing the RNA/DNA binding protein TDP-43. Using a yeast model of ALS exhibiting TDP-43 dependent toxicity, we now show that TDP-43 overexpression dramatically alters cell shape and reduces ubiquitin dependent proteolysis of a reporter construct. Furthermore, we show that an excess of the Hsp40 chaperone, Sis1, reduced TDP-43’s effect on toxicity, cell shape and proteolysis. The strength of these effects was influenced by the presence of the endogenous yeast prion, [PIN+]. Although overexpression of Sis1 altered the TDP-43 aggregation pattern, we did not detect physical association of Sis1 with TDP-43, suggesting the possibility of indirect effects on TDP-43 aggregation. Furthermore, overexpression of the mammalian Sis1 homologue, DNAJB1, relieves TDP-43 mediated toxicity in primary rodent cortical neurons, suggesting that Sis1 and its homologues may have neuroprotective effects in ALS. Many neurodegenerative diseases are associated with aggregation of specific proteins. Thus we are interested in factors that influence the aggregation and how the aggregated proteins are associated with pathology. Here, we study a protein called TDP-43 that is frequently aggregated in the neurons of patients with amyotrophic lateral sclerosis (ALS). TDP-43 aggregates and is toxic when expressed in yeast, providing a useful model for ALS. Remarkably, a protein that modified TDP-43 toxicity in yeast successfully predicted a new ALS susceptibility gene in humans. We now report a new modifier of TDP-43 toxicity, Sis1. We show that expression of TDP-43 in yeast inhibits degradation of damaged protein, while overexpression of Sis1 restores degradation. Thus suggests a link between protein degradation and TDP-43 toxicity. Furthermore we show that a mammalian protein similar to Sis1 reduces TDP-43 toxicity in primary rodent neurons. This identifies the mammalian Sis1-like gene as a new ALS therapeutic target and possible susceptibility gene.
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8
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Lee J, Kim SY, Hwang KJ, Ju YR, Woo HJ. Prion diseases as transmissible zoonotic diseases. Osong Public Health Res Perspect 2014; 4:57-66. [PMID: 24159531 PMCID: PMC3747681 DOI: 10.1016/j.phrp.2012.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 11/18/2022] Open
Abstract
Prion diseases, also called transmissible spongiform encephalopathies (TSEs), lead to neurological dysfunction in animals and are fatal. Infectious prion proteins are causative agents of many mammalian TSEs, including scrapie (in sheep), chronic wasting disease (in deer and elk), bovine spongiform encephalopathy (BSE; in cattle), and Creutzfeldt-Jakob disease (CJD; in humans). BSE, better known as mad cow disease, is among the many recently discovered zoonotic diseases. BSE cases were first reported in the United Kingdom in 1986. Variant CJD (vCJD) is a disease that was first detected in 1996, which affects humans and is linked to the BSE epidemic in cattle. vCJD is presumed to be caused by consumption of contaminated meat and other food products derived from affected cattle. The BSE epidemic peaked in 1992 and decreased thereafter; this decline is continuing sharply owing to intensive surveillance and screening programs in the Western world. However, there are still new outbreaks and/or progression of prion diseases, including atypical BSE, and iatrogenic CJD and vCJD via organ transplantation and blood transfusion. This paper summarizes studies on prions, particularly on prion molecular mechanisms, BSE, vCJD, and diagnostic procedures. Risk perception and communication policies of the European Union for the prevention of prion diseases are also addressed to provide recommendations for appropriate government policies in Korea.
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Affiliation(s)
- Jeongmin Lee
- Laboratory of Immunology, College of Veterinary Medicine, Seoul National University, Seoul,
Korea
- Division of Zoonoses, Korea National Institute of Health, Osong,
Korea
| | - Su Yeon Kim
- Division of Zoonoses, Korea National Institute of Health, Osong,
Korea
| | - Kyu Jam Hwang
- Division of Zoonoses, Korea National Institute of Health, Osong,
Korea
| | - Young Ran Ju
- Division of Zoonoses, Korea National Institute of Health, Osong,
Korea
| | - Hee-Jong Woo
- Laboratory of Immunology, College of Veterinary Medicine, Seoul National University, Seoul,
Korea
- Corresponding author. E-mail:
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Winkler J, Tyedmers J, Bukau B, Mogk A. Hsp70 targets Hsp100 chaperones to substrates for protein disaggregation and prion fragmentation. ACTA ACUST UNITED AC 2012; 198:387-404. [PMID: 22869599 PMCID: PMC3413357 DOI: 10.1083/jcb.201201074] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The Hsp70 system recruits ClpB/Hsp104 to the surface of stress-induced protein aggregates and prion fibrils. Hsp100 and Hsp70 chaperones in bacteria, yeast, and plants cooperate to reactivate aggregated proteins. Disaggregation relies on Hsp70 function and on ATP-dependent threading of aggregated polypeptides through the pore of the Hsp100 AAA+ hexamer. In yeast, both chaperones also promote propagation of prions by fibril fragmentation, but their functional interplay is controversial. Here, we demonstrate that Hsp70 chaperones were essential for species-specific targeting of their Hsp100 partner chaperones ClpB and Hsp104, respectively, to heat-induced protein aggregates in vivo. Hsp70 inactivation in yeast also abrogated Hsp104 targeting to almost all prions tested and reduced fibril mobility, which indicates that fibril fragmentation by Hsp104 requires Hsp70. The Sup35 prion was unique in allowing Hsp70-independent association of Hsp104 via its N-terminal domain, which, however, was nonproductive. Hsp104 overproduction even outcompeted Hsp70 for Sup35 prion binding, which explains why this condition prevented Sup35 fragmentation and caused prion curing. Our findings indicate a conserved mechanism of Hsp70–Hsp100 cooperation at the surface of protein aggregates and prion fibrils.
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Affiliation(s)
- Juliane Winkler
- Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, Universität Heidelberg, Heidelberg D-69120, Germany
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10
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Winkler J, Tyedmers J, Bukau B, Mogk A. Chaperone networks in protein disaggregation and prion propagation. J Struct Biol 2012; 179:152-60. [PMID: 22580344 DOI: 10.1016/j.jsb.2012.05.002] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/27/2012] [Accepted: 05/01/2012] [Indexed: 11/30/2022]
Abstract
The oligomeric AAA+ chaperones Escherichia coli ClpB and Saccharomyces cerevisiae Hsp104 cooperate with cognate Hsp70/Hsp40 chaperone machineries in the reactivation of aggregated proteins in E. coli and S. cerevisiae. In addition, Hsp104 and Hsp70/Hsp40 are crucial for the maintenance of prion aggregates in yeast cells. While the bichaperone system efficiently solubilizes stress-generated amorphous aggregates, structurally highly ordered prion fibrils are only partially processed, resulting in the generation of fragmented prion seeds that can be transmitted to daughter cells for stable inheritance. Here, we describe and discuss the most recent mechanistic findings on yeast Hsp104 and Hsp70/Hsp40 cooperation in the remodeling of both types of aggregates, emphasizing similarities in the mechanism but also differences in the sensitivities towards chaperone activities.
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Affiliation(s)
- Juliane Winkler
- Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
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11
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DiSalvo S, Serio TR. Insights into prion biology: integrating a protein misfolding pathway with its cellular environment. Prion 2011; 5:76-83. [PMID: 21654204 DOI: 10.4161/pri.5.2.16413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Protein misfolding and assembly into ordered, self-templating aggregates (amyloid) has emerged as a novel mechanism for regulating protein function. For a subclass of amyloidogenic proteins known as prions, this process induces transmissible changes in normal cellular physiology, ranging from neurodegenerative disease in animals and humans to new traits in fungi. The severity and stability of these altered phenotypic states can be attenuated by the conformation or amino-acid sequence of the prion, but in most of these cases, the protein retains the ability to form amyloid in vitro. Thus, our ability to link amyloid formation in vitro with its biological consequences in vivo remains a challenge. In two recent studies, we have begun to address this disconnect by assessing the effects of the cellular environment on traits associated with the misfolding of the yeast prion Sup35. Remarkably, the effects of quality control pathways and of limitations on protein transfer in vivo amplify the effects of even slight differences in the efficiency of Sup35 misfolding, leading to dramatic changes in the associated phenotype. Together, our studies suggest that the interplay between protein misfolding pathways and their cellular context is a crucial contributor to prion biology.
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Affiliation(s)
- Susanne DiSalvo
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA
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12
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Tsuji T, Kawai-Noma S, Pack CG, Terajima H, Yajima J, Nishizaka T, Kinjo M, Taguchi H. Single-particle tracking of quantum dot-conjugated prion proteins inside yeast cells. Biochem Biophys Res Commun 2011; 405:638-43. [PMID: 21277285 DOI: 10.1016/j.bbrc.2011.01.083] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Accepted: 01/24/2011] [Indexed: 12/15/2022]
Abstract
Yeast is a model eukaryote with a variety of biological resources. Here we developed a method to track a quantum dot (QD)-conjugated protein in the budding yeast Saccharomyces cerevisiae. We chemically conjugated QDs with the yeast prion Sup35, incorporated them into yeast spheroplasts, and tracked the motions by conventional two-dimensional or three-dimensional tracking microscopy. The method paves the way toward the individual tracking of proteins of interest inside living yeast cells.
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Affiliation(s)
- Toshikazu Tsuji
- Department of Biomolecular Engineering, Graduate School of Biosciences and Biotechnology, Tokyo Institute of Technology, B56, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
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13
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Derdowski A, Sindi SS, Klaips CL, DiSalvo S, Serio TR. A size threshold limits prion transmission and establishes phenotypic diversity. Science 2010; 330:680-3. [PMID: 21030659 DOI: 10.1126/science.1197785] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
According to the prion hypothesis, atypical phenotypes arise when a prion protein adopts an alternative conformation and persist when that form assembles into self-replicating aggregates. Amyloid formation in vitro provides a model for this protein-misfolding pathway, but the mechanism by which this process interacts with the cellular environment to produce transmissible phenotypes is poorly understood. Using the yeast prion Sup35/[PSI(+)], we found that protein conformation determined the size distribution of aggregates through its interactions with a molecular chaperone. Shifts in this range created variations in aggregate abundance among cells because of a size threshold for transmission, and this heterogeneity, along with aggregate growth and fragmentation, induced age-dependent fluctuations in phenotype. Thus, prion conformations may specify phenotypes as population averages in a dynamic system.
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Affiliation(s)
- Aaron Derdowski
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Post Office Box G-L2, Providence, RI 02912, USA
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14
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Abstract
Prions are infectious proteins, in which self-propagating amyloid conformations of proteins are transmitted. The budding yeast Saccharomyces cerevisiae, one of the best-studied model eukaryotes, also has prions, and thus provides a tractable model system with which to understand the mechanisms of prion phenomena. The yeast prions are protein-based heritable elements, such as [PSI(+)], in which aggregates of prion proteins are transmitted to daughter cells in a non-Mendelian manner. Although the genetic approaches preceded the yeast prion studies, recent investigations of the dynamic aspects of the prion proteins have unraveled the molecular mechanisms by which prions are propagated and transmitted. In particular, several lines of evidence have revealed that the oligomeric species of prion proteins dispersed in the cytoplasm are critical for the transmission. This review summarizes the topics on the transmissible entities of yeast prions, focusing mainly on the Sup35 protein in [PSI(+)].
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Affiliation(s)
- Hideki Taguchi
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha, Kashiwa, Chiba, Japan.
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15
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Sindi SS, Serio TR. Prion dynamics and the quest for the genetic determinant in protein-only inheritance. Curr Opin Microbiol 2009; 12:623-30. [PMID: 19864176 DOI: 10.1016/j.mib.2009.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/12/2009] [Accepted: 09/14/2009] [Indexed: 01/24/2023]
Abstract
According to the prion hypothesis, proteins may act in atypical roles as genetic elements of infectivity and inheritance by undergoing self-replicating changes in physical state. While the preponderance of evidence strongly supports this concept particularly in fungi, the detailed mechanisms by which distinct protein forms specify unique phenotypes are emerging concepts. A particularly active area of investigation is the molecular nature of the heritable species, which has been probed through genetic, biochemical, and cell biological experimentation as well as by mathematical modeling. Here, we suggest that these studies are converging to implicate small aggregates composed of prion-state conformers as the transmissible genetic determinants of protein-based phenotypes.
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Affiliation(s)
- Suzanne S Sindi
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 185 Meeting St., Box G-L2, Providence, RI 02912, USA
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Pezza JA, Langseth SX, Raupp Yamamoto R, Doris SM, Ulin SP, Salomon AR, Serio TR. The NatA acetyltransferase couples Sup35 prion complexes to the [PSI+] phenotype. Mol Biol Cell 2008; 20:1068-80. [PMID: 19073888 DOI: 10.1091/mbc.e08-04-0436] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Protein-only (prion) epigenetic elements confer unique phenotypes by adopting alternate conformations that specify new traits. Given the conformational flexibility of prion proteins, protein-only inheritance requires efficient self-replication of the underlying conformation. To explore the cellular regulation of conformational self-replication and its phenotypic effects, we analyzed genetic interactions between [PSI(+)], a prion form of the S. cerevisiae Sup35 protein (Sup35([PSI+])), and the three N(alpha)-acetyltransferases, NatA, NatB, and NatC, which collectively modify approximately 50% of yeast proteins. Although prion propagation proceeds normally in the absence of NatB or NatC, the [PSI(+)] phenotype is reversed in strains lacking NatA. Despite this change in phenotype, [PSI(+)] NatA mutants continue to propagate heritable Sup35([PSI+]). This uncoupling of protein state and phenotype does not arise through a decrease in the number or activity of prion templates (propagons) or through an increase in soluble Sup35. Rather, NatA null strains are specifically impaired in establishing the translation termination defect that normally accompanies Sup35 incorporation into prion complexes. The NatA effect cannot be explained by the modification of known components of the [PSI(+)] prion cycle including Sup35; thus, novel acetylated cellular factors must act to establish and maintain the tight link between Sup35([PSI+]) complexes and their phenotypic effects.
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Affiliation(s)
- John A Pezza
- Brown University, Department of Molecular Biology, Cell Biology, and Biochemistry, Providence, RI 02912, USA
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