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Al-Ansari M, Fitzsimons T, Wei W, Goldberg MW, Kunieda T, Quinlan RA. The major inducible small heat shock protein HSP20-3 in the tardigrade Ramazzottius varieornatus forms filament-like structures and is an active chaperone. Cell Stress Chaperones 2024; 29:51-65. [PMID: 38330543 PMCID: PMC10939073 DOI: 10.1016/j.cstres.2023.12.001] [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: 11/28/2023] [Accepted: 12/03/2023] [Indexed: 02/10/2024] Open
Abstract
The tardigrade Ramazzottius varieornatus has remarkable resilience to a range of environmental stresses. In this study, we have characterised two members of the small heat shock protein (sHSP) family in R. varieornatus, HSP20-3 and HSP20-6. These are the most highly upregulated sHSPs in response to a 24 h heat shock at 35 0C of adult tardigrades with HSP20-3 being one of the most highly upregulated gene in the whole transcriptome. Both R. varieornatus sHSPs and the human sHSP, CRYAB (HSPB5), were produced recombinantly for comparative structure-function studies. HSP20-3 exhibited a superior chaperone activity than human CRYAB in a heat-induced protein aggregation assay. Both tardigrade sHSPs also formed larger oligomers than CRYAB as assessed by size exclusion chromatography and transmission electron microscopy of negatively stained samples. Whilst both HSP20-3 and HSP20-6 formed particles that were variable in size and larger than the particles formed by CRYAB, only HSP20-3 formed filament-like structures. The particles and filament-like structures formed by HSP20-3 appear inter-related as the filament-like structures often had particles located at their ends. Sequence analyses identified two unique features; an insertion in the middle region of the N-terminal domain (NTD) and preceding the critical-sequence identified in CRYAB, as well as a repeated QNTN-motif located in the C-terminal domain of HSP20-3. The NTD insertion is expected to affect protein-protein interactions and subunit oligomerisation. Removal of the repeated QNTN-motif abolished HSP20-3 chaperone activity and also affected the assembly of the filament-like structures. We discuss the potential contribution of HSP20-3 to protein condensate formation.
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Affiliation(s)
- Mohammad Al-Ansari
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK; Department of Biochemistry, Health Sciences Centre, Kuwait University, Kuwait
| | - Taylor Fitzsimons
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK
| | - Wenbin Wei
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK.
| | - Martin W Goldberg
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK
| | - Takekazu Kunieda
- Department of Biological Sciences, The University of Tokyo, Japan
| | - Roy A Quinlan
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK; Department of Biological Structure, University of Washington, Seattle, WA 98195, USA.
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Xu W, Liang Y, Zhu Y, Sun T, Yuan Z, Han X. Proteomic study of aqueous humour in diabetic patients with cataracts by TMT combined with HPLC-MS/MS. BMC Ophthalmol 2023; 23:435. [PMID: 37884923 PMCID: PMC10604804 DOI: 10.1186/s12886-023-03162-2] [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: 01/08/2023] [Accepted: 10/03/2023] [Indexed: 10/28/2023] Open
Abstract
BACKGROUND The purpose of this study is to identify the proteomic differences between the aqueous humour of diabetes patients with cataracts and that of non-diabetic sufferers of cataracts in a clinical setting. METHODS Patients were divided into the diabetic experimental group and the non-diabetic control group. Aqueous humour specimens were obtained via cataract surgery. Sample proteins were treated with a TMT reagent, separated using a cation chromatography column, and analysed using a C18 desalting column. Proteins were identified using HPLC-MS/MS. The differential proteins were identified using both a p value of < 0.05 and a fold change of > 1.2. GO classification enrichment analysis, KEGG pathway enrichment analysis, protein interaction network analysis, and ingenuity pathway analysis were all carried out. The expression level of four differential proteins were verified by Western blot, and GC and TTR expressions were further examined using an expanded sample pool. RESULTS The postprandial glucose levels between the experimental group (9.40 ± 1.35 mmol/L) and the control group (6.56 ± 0.81 mmol/L) were significantly different, with a p value of 1.16E-06. It is important to note, however, that the baseline levels of the parameters showed no statistical differences. In total, 397 aqueous humour proteins were identified; of these, 137 showed significant differences, with 63 upregulated ones and 74 down-regulated ones. The differential proteins play important roles in numerous biological processes and pathways, such as complement and coagulation cascades (p = 1.71E-09). Some of these differential proteins are associated with diabetic retinal degeneration and other diabetic complications. Differential proteins, such as HP, GC, and TTR, have high node degree in the protein interaction network. Western blot results further confirmed that GC were down-regulated while TTR was up-regulated in aqueous humour under diabetic condition. CONCLUSION A list of differential proteins in the human aqueous humour of diabetic patients was established. Proteins with high interaction scores as per protein interaction analysis, such as GC and TTR, were further verified and could potentially be used as early diagnostic markers for diabetic eye complications in clinical practice.
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Affiliation(s)
- Weihai Xu
- Department of Ophthalmology, Binhai county people's hospital, Yancheng, Jiangsu, China
- Department of Ophthalmology, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ya Liang
- Department of Ophthalmology, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yunxia Zhu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Tong Sun
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, China.
| | - Zhilan Yuan
- Department of Ophthalmology, the First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China.
| | - Xiao Han
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, China.
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Tedesco B, Vendredy L, Adriaenssens E, Cozzi M, Asselbergh B, Crippa V, Cristofani R, Rusmini P, Ferrari V, Casarotto E, Chierichetti M, Mina F, Pramaggiore P, Galbiati M, Piccolella M, Baets J, Baeke F, De Rycke R, Mouly V, Laurenzi T, Eberini I, Vihola A, Udd B, Weiss L, Kimonis V, Timmerman V, Poletti A. HSPB8 frameshift mutant aggregates weaken chaperone-assisted selective autophagy in neuromyopathies. Autophagy 2023:1-23. [PMID: 36854646 DOI: 10.1080/15548627.2023.2179780] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
Chaperone-assisted selective autophagy (CASA) is a highly selective pathway for the disposal of misfolding and aggregating proteins. In muscle, CASA assures muscle integrity by favoring the turnover of structural components damaged by mechanical strain. In neurons, CASA promotes the removal of aggregating substrates. A crucial player of CASA is HSPB8 (heat shock protein family B (small) member 8), which acts in a complex with HSPA, their cochaperone BAG3, and the E3 ubiquitin ligase STUB1. Recently, four novel HSPB8 frameshift (fs) gene mutations have been linked to neuromyopathies, and encode carboxy-terminally mutated HSPB8, sharing a common C-terminal extension. Here, we analyzed the biochemical and functional alterations associated with the HSPB8_fs mutant proteins. We demonstrated that HSPB8_fs mutants are highly insoluble and tend to form proteinaceous aggregates in the cytoplasm. Notably, all HSPB8 frameshift mutants retain their ability to interact with CASA members but sequester them into the HSPB8-positive aggregates together with two autophagy receptors SQSTM1/p62 and TAX1BP1. This copartitioning process negatively affects the CASA capability to remove its clients and causes a general failure in proteostasis response. Further analyses revealed that the aggregation of the HSPB8_fs mutants occurs independently of the other CASA members or from the autophagy receptors interaction, but it is an intrinsic feature of the mutated amino acid sequence. HSPB8_fs mutants aggregation alters the differentiation capacity of muscle cells and impairs sarcomere organization. Collectively, these results shed light on a potential pathogenic mechanism shared by the HSPB8_fs mutants described in neuromuscular diseases.Abbreviations : ACD: α-crystallin domain; ACTN: actinin alpha; BAG3: BAG cochaperone 3; C: carboxy; CASA: chaperone-assisted selective autophagy; CE: carboxy-terminal extension; CLEM: correlative light and electron microscopy; CMT2L: Charcot-Marie-Tooth type 2L; CTR: carboxy-terminal region; dHMNII: distal hereditary motor neuropathy type II; EV: empty vector; FRA: filter retardation assay; fs: frameshift; HSPA/HSP70: heat shock protein family A (Hsp70); HSPB1/Hsp27: heat shock protein family B (small) member 1; HSPB8/Hsp22: heat shock protein family B (small) member 8; HTT: huntingtin; KO: knockout; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3 beta; MD: molecular dynamics; MTOC: microtubule organizing center; MYH: myosin heavy chain; MYOG: myogenin; NBR1: NBR1 autophagy cargo receptor; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; NSC34: Neuroblastoma X Spinal Cord 34; OPTN: optineurin; polyQ: polyglutamine; SQSTM1/p62: sequestosome 1; STUB1/CHIP: STIP1 homology and U-box containing protein 1; TARDBP/TDP-43: TAR DNA binding protein; TAX1BP1: Tax1 binding protein 1; TUBA: tubulin alpha; WT: wild-type.
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Affiliation(s)
- Barbara Tedesco
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy.,Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Leen Vendredy
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences and Institute Born Bunge, University of Antwerp, Antwerpen, Belgium
| | - Elias Adriaenssens
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences and Institute Born Bunge, University of Antwerp, Antwerpen, Belgium
| | - Marta Cozzi
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Bob Asselbergh
- Neuromics Support Facility, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium.,Neuromics Support Facility, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Valeria Crippa
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Riccardo Cristofani
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Paola Rusmini
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Veronica Ferrari
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Elena Casarotto
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Marta Chierichetti
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Francesco Mina
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Paola Pramaggiore
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Mariarita Galbiati
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Margherita Piccolella
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Jonathan Baets
- Laboratory of Neuromuscular Pathology, Institute Born Bunge, and Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
| | - Femke Baeke
- Department of Biomedical Molecular Biology, and VIB Center for Inflammation Research, and VIB Bioimaging Core, Ghent University Ghent, Belgium
| | - Riet De Rycke
- Department of Biomedical Molecular Biology, and VIB Center for Inflammation Research, and VIB Bioimaging Core, Ghent University Ghent, Belgium
| | - Vincent Mouly
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Tommaso Laurenzi
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Ivano Eberini
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
| | - Anna Vihola
- Folkhälsan Research Center, University of Helsinki, Helsinki, Finland.,Neuromuscular Research Center, Tampere University Hospital, Tampere, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, University of Helsinki, Helsinki, Finland.,Neuromuscular Research Center, Tampere University Hospital, Tampere, Finland.,Vasa Central Hospital, Vasa, Finland
| | - Lan Weiss
- Department of Pediatrics, University of California, Irvine, Lombardy, United States
| | - Virginia Kimonis
- Department of Pediatrics, University of California, Irvine, Lombardy, United States
| | - Vincent Timmerman
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences and Institute Born Bunge, University of Antwerp, Antwerpen, Belgium
| | - Angelo Poletti
- Dipartimento di Scienze Farmacologiche e Biomolecolari "Rodolfo Paoletti", Dipartimento di Eccellenza 2018-2027, Università degli Studi di Milano, Milan, Italy
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Budnar P, Tangirala R, Bakthisaran R, Rao CM. Protein Aggregation and Cataract: Role of Age-Related Modifications and Mutations in α-Crystallins. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:225-241. [PMID: 35526854 DOI: 10.1134/s000629792203004x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
* The article is published as a part of the Special Issue "Protein Misfolding and Aggregation in Cataract Disorders" (Vol. 87, No. 2). ** To whom correspondence should be addressed. Cataract is a major cause of blindness. Due to the lack of protein turnover, lens proteins accumulate age-related and environmental modifications that alter their native conformation, leading to the formation of aggregation-prone intermediates, as well as insoluble and light-scattering aggregates, thus compromising lens transparency. The lens protein, α-crystallin, is a molecular chaperone that prevents protein aggregation, thereby maintaining lens transparency. However, mutations or post-translational modifications, such as oxidation, deamidation, truncation and crosslinking, can render α-crystallins ineffective and lead to the disease exacerbation. Here, we describe such mutations and alterations, as well as their consequences. Age-related modifications in α-crystallins affect their structure, oligomerization, and chaperone function. Mutations in α-crystallins can lead to the aggregation/intracellular inclusions attributable to the perturbation of structure and oligomeric assembly and resulting in the rearrangement of aggregation-prone regions. Such rearrangements can lead to the exposure of hitherto buried aggregation-prone regions, thereby populating aggregation-prone state(s) and facilitating amorphous/amyloid aggregation and/or inappropriate interactions with cellular components. Investigations of the mutation-induced changes in the structure, oligomer assembly, aggregation mechanisms, and interactomes of α-crystallins will be useful in fighting protein aggregation-related diseases.
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Affiliation(s)
- Prashanth Budnar
- Centre for Cellular and Molecular Biology (CCMB), Council of Scientific and Industrial Research (CSIR), Uppal Road, Hyderabad, 500007, India
| | - Ramakrishna Tangirala
- Centre for Cellular and Molecular Biology (CCMB), Council of Scientific and Industrial Research (CSIR), Uppal Road, Hyderabad, 500007, India
| | - Raman Bakthisaran
- Centre for Cellular and Molecular Biology (CCMB), Council of Scientific and Industrial Research (CSIR), Uppal Road, Hyderabad, 500007, India
| | - Ch Mohan Rao
- Centre for Cellular and Molecular Biology (CCMB), Council of Scientific and Industrial Research (CSIR), Uppal Road, Hyderabad, 500007, India.
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5
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Tedesco B, Cristofani R, Ferrari V, Cozzi M, Rusmini P, Casarotto E, Chierichetti M, Mina F, Galbiati M, Piccolella M, Crippa V, Poletti A. Insights on Human Small Heat Shock Proteins and Their Alterations in Diseases. Front Mol Biosci 2022; 9:842149. [PMID: 35281256 PMCID: PMC8913478 DOI: 10.3389/fmolb.2022.842149] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
The family of the human small Heat Shock Proteins (HSPBs) consists of ten members of chaperones (HSPB1-HSPB10), characterized by a low molecular weight and capable of dimerization and oligomerization forming large homo- or hetero-complexes. All HSPBs possess a highly conserved centrally located α-crystallin domain and poorly conserved N- and C-terminal domains. The main feature of HSPBs is to exert cytoprotective functions by preserving proteostasis, assuring the structural maintenance of the cytoskeleton and acting in response to cellular stresses and apoptosis. HSPBs take part in cell homeostasis by acting as holdases, which is the ability to interact with a substrate preventing its aggregation. In addition, HSPBs cooperate in substrates refolding driven by other chaperones or, alternatively, promote substrate routing to degradation. Notably, while some HSPBs are ubiquitously expressed, others show peculiar tissue-specific expression. Cardiac muscle, skeletal muscle and neurons show high expression levels for a wide variety of HSPBs. Indeed, most of the mutations identified in HSPBs are associated to cardiomyopathies, myopathies, and motor neuropathies. Instead, mutations in HSPB4 and HSPB5, which are also expressed in lens, have been associated with cataract. Mutations of HSPBs family members encompass base substitutions, insertions, and deletions, resulting in single amino acid substitutions or in the generation of truncated or elongated proteins. This review will provide an updated overview of disease-related mutations in HSPBs focusing on the structural and biochemical effects of mutations and their functional consequences.
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Affiliation(s)
- B. Tedesco
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - R. Cristofani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - V. Ferrari
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - M. Cozzi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - P. Rusmini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - E. Casarotto
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - M. Chierichetti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - F. Mina
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - M. Galbiati
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - M. Piccolella
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - V. Crippa
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - A. Poletti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
- *Correspondence: A. Poletti,
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Nucleosomal association and altered interactome underlie the mechanism of cataract caused by the R54C mutation of αA-crystallin. Biochim Biophys Acta Gen Subj 2021; 1865:129846. [PMID: 33444727 DOI: 10.1016/j.bbagen.2021.129846] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND αA-crystallin plays an important role in eye lens development. Its N-terminal domain is implicated in several important biological functions. Mutations in certain conserved arginine residues in the N-terminal region of αA-crystallin lead to cataract with characteristic cytoplasmic/nuclear aggregation of the mutant protein. In this study, we attempt to gain mechanistic insights into the congenital cataract caused by the R54C mutation in human αA-crystallin. METHODS We used several spectroscopic techniques to investigate the structure and function of the wild-type and R54CαA-crystallin. Immunoprecipitation, chromatin-enrichment followed by western blotting, immunofluorescence and cell-viability assay were performed to study the interaction partners, chromatin-association, stress-like response and cell-death caused by the mutant. RESULTS Although R54CαA-crystallin exhibited slight changes in quaternary structure, its chaperone-like activity was comparable to that of wild-type. When expressed in lens epithelial cells, R54CαA-crystallin exhibited a speckled appearance in the nucleus rather than cytoplasmic localization. R54CαA-crystallin triggered a stress-like response, resulting in nuclear translocation of αB-crystallin, disassembly of cytoskeletal elements and activation of caspase 3, leading to apoptosis. Analysis of the "interactome" revealed an increase in interaction of the mutant protein with nucleosomal histones, and its association with chromatin. CONCLUSIONS The study shows that alteration of "interactome" and nucleosomal association, rather than loss of chaperone-like activity, is the molecular basis of cataract caused by the R54C mutation in αA-crystallin. GENERAL SIGNIFICANCE The study provides a novel mechanism of cataract caused by a mutant of αA-crystallin, and sheds light on the possible mechanism of stress and cell death caused by such nuclear inclusions.
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Grosas AB, Rekas A, Mata JP, Thorn DC, Carver JA. The Aggregation of αB-Crystallin under Crowding Conditions Is Prevented by αA-Crystallin: Implications for α-Crystallin Stability and Lens Transparency. J Mol Biol 2020; 432:5593-5613. [PMID: 32827531 DOI: 10.1016/j.jmb.2020.08.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/13/2020] [Accepted: 08/13/2020] [Indexed: 02/08/2023]
Abstract
One of the most crowded biological environments is the eye lens which contains a high concentration of crystallin proteins. The molecular chaperones αB-crystallin (αBc) with its lens partner αA-crystallin (αAc) prevent deleterious crystallin aggregation and cataract formation. However, some forms of cataract are associated with structural alteration and dysfunction of αBc. While many studies have investigated the structure and function of αBc under dilute in vitro conditions, the effect of crowding on these aspects is not well understood despite its in vivo relevance. The structure and chaperone ability of αBc under conditions that mimic the crowded lens environment were investigated using the polysaccharide Ficoll 400 and bovine γ-crystallin as crowding agents and a variety of biophysical methods, principally contrast variation small-angle neutron scattering. Under crowding conditions, αBc unfolds, increases its size/oligomeric state, decreases its thermal stability and chaperone ability, and forms kinetically distinct amorphous and fibrillar aggregates. However, the presence of αAc stabilizes αBc against aggregation. These observations provide a rationale, at the molecular level, for the aggregation of αBc in the crowded lens, a process that exhibits structural and functional similarities to the aggregation of cataract-associated αBc mutants R120G and D109A under dilute conditions. Strategies that maintain or restore αBc stability, as αAc does, may provide therapeutic avenues for the treatment of cataract.
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Affiliation(s)
- Aidan B Grosas
- Research School of Chemistry, The Australian National University, Canberra, ACT, 2601, Australia
| | - Agata Rekas
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Jitendra P Mata
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - David C Thorn
- Research School of Chemistry, The Australian National University, Canberra, ACT, 2601, Australia
| | - John A Carver
- Research School of Chemistry, The Australian National University, Canberra, ACT, 2601, Australia.
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8
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Neuromuscular Diseases Due to Chaperone Mutations: A Review and Some New Results. Int J Mol Sci 2020; 21:ijms21041409. [PMID: 32093037 PMCID: PMC7073051 DOI: 10.3390/ijms21041409] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 12/12/2022] Open
Abstract
Skeletal muscle and the nervous system depend on efficient protein quality control, and they express chaperones and cochaperones at high levels to maintain protein homeostasis. Mutations in many of these proteins cause neuromuscular diseases, myopathies, and hereditary motor and sensorimotor neuropathies. In this review, we cover mutations in DNAJB6, DNAJB2, αB-crystallin (CRYAB, HSPB5), HSPB1, HSPB3, HSPB8, and BAG3, and discuss the molecular mechanisms by which they cause neuromuscular disease. In addition, previously unpublished results are presented, showing downstream effects of BAG3 p.P209L on DNAJB6 turnover and localization.
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9
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Ma K, Luo D, Tian T, Li N, He X, Rao C, Zhong B, Lu X. A novel homozygous initiation codon variant associated with infantile alpha-Bcrystallinopathy in a Chinese family. Mol Genet Genomic Med 2019; 7:e825. [PMID: 31215171 PMCID: PMC6687638 DOI: 10.1002/mgg3.825] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/22/2019] [Accepted: 05/29/2019] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Due to inconsistencies with reported myofibrillar myopathy (MFM), including autosomal dominant inheritance, late onset and a slowly progressive course, the severe, recessively inherited form of CRYAB (alpha-B crystallin) gene-related infantile MFM has been suggested. Here, we report an infant in a Chinese family with fatal neonatal-onset hypertonic MFM with a novel CRYAB homozygous variant (c.3G > A (p.Met1?)). METHODS Muscle biopsy indicated that muscle fibers showed a uniformly small diameter, cell atrophy, and visible focal muscle fiber degeneration and necrosis consistent with myogenic myopathy. We performed the whole exome sequencing of pathogenic genes and identified it as MFM. RESULTS The proband presented with profound muscle stiffness, progressive respiratory distress and a concurrent abnormal increase in myocardial enzymogram, and the patient died in the 17th month of life. Muscle biopsy and electron microscopy results were consistent with ultramicroscopic myogenic damage and pathological changes. Mutation analysis of the proband identified a novel rare homozygous mutation in the initiation codon of the CRYAB gene, which was inherited from currently asymptomatic, heterozygous carrier parents, and his heterozygous biological brother is unaffected. CONCLUSIONS This article reports one infant with CRYAB-related neonatal onset MFM with a novel homozygous variant in CRYAB. To our knowledge, this is the first reported case of infantile alpha-Bcrystallinopathy in the Chinese population.
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Affiliation(s)
- Keze Ma
- Department of Neonates, Dongguan Children's Hospital, Dongguan, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, China
| | - Dong Luo
- Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, China.,Medical Laboratory, Dongguan Children's Hospital, Dongguan, China
| | - Tian Tian
- Department of Pathology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ning Li
- Department of Neonates, Dongguan Children's Hospital, Dongguan, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, China
| | - Xiaoguang He
- Department of Neonates, Dongguan Children's Hospital, Dongguan, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, China
| | - Chunbao Rao
- Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, China.,Medical Laboratory, Dongguan Children's Hospital, Dongguan, China
| | - Baimao Zhong
- Department of Neonates, Dongguan Children's Hospital, Dongguan, China.,Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, China
| | - Xiaomei Lu
- Department of Medical and Molecular Genetics, Dongguan Institute of Pediatrics, Dongguan, China.,Medical Laboratory, Dongguan Children's Hospital, Dongguan, China
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10
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Carver JA, Grosas AB, Ecroyd H, Quinlan RA. The functional roles of the unstructured N- and C-terminal regions in αB-crystallin and other mammalian small heat-shock proteins. Cell Stress Chaperones 2017; 22:627-638. [PMID: 28391594 PMCID: PMC5465038 DOI: 10.1007/s12192-017-0789-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/06/2017] [Accepted: 03/16/2017] [Indexed: 01/18/2023] Open
Abstract
Small heat-shock proteins (sHsps), such as αB-crystallin, are one of the major classes of molecular chaperone proteins. In vivo, under conditions of cellular stress, sHsps are the principal defence proteins that prevent large-scale protein aggregation. Progress in determining the structure of sHsps has been significant recently, particularly in relation to the conserved, central and β-sheet structured α-crystallin domain (ACD). However, an understanding of the structure and functional roles of the N- and C-terminal flanking regions has proved elusive mainly because of their unstructured and dynamic nature. In this paper, we propose functional roles for both flanking regions, based around three properties: (i) they act in a localised crowding manner to regulate interactions with target proteins during chaperone action, (ii) they protect the ACD from deleterious amyloid fibril formation and (iii) the flexibility of these regions, particularly at the extreme C-terminus in mammalian sHsps, provides solubility for sHsps under chaperone and non-chaperone conditions. In the eye lens, these properties are highly relevant as the crystallin proteins, in particular the two sHsps αA- and αB-crystallin, are present at very high concentrations.
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Affiliation(s)
- John A Carver
- Research School of Chemistry, The Australian National University, Acton, ACT, 2601, Australia.
| | - Aidan B Grosas
- Research School of Chemistry, The Australian National University, Acton, ACT, 2601, Australia
| | - Heath Ecroyd
- School of Biological Sciences and the Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Roy A Quinlan
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK
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11
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Zhou Q, Shi X, Zhang K, Shi C, Huang L, Chang Z. The Function of Ile-X-Ile Motif in the Oligomerization and Chaperone-Like Activity of Small Heat Shock Protein AgsA at Room Temperature. Protein J 2016; 35:401-406. [PMID: 27812886 DOI: 10.1007/s10930-016-9681-y] [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] [Indexed: 11/30/2022]
Abstract
Small heat shock proteins assemble as large oligomers in vitro and exhibit ATP-independent chaperone activities. Ile-X-Ile motif is essential in both the function and oligomer formation. AgsA of Salmonella enterica serovar Typhimurium has been demonstrated to adopt large oligomeric structure and possess strong chaperone activity. Size exclusion chromatography, non-denaturing pore gradient PAGE, and negatively stain electron microscopic analysis of the various C-terminal truncated mutants were performed to investigate the role of Ile-X-Ile motif in the oligomer assembly of AgsA. By measuring the ability to prevent insulin from aggregating induced by TCEP, the chaperone-like activity of AgsA and the C-terminal truncated mutants at room temperature were determined. We found that the truncated mutants with Ile-X-Ile motif partially or fully deleted lost the ability to form large oligomers. Contrast to wild type AgsA which displayed weak chaperone-like activity, those mutants shown significantly enhanced activities at room temperature. In summary, biochemical experiment, activity assay and electron microscopic analysis suggested that Ile-X-Ile motif is essential in oligomer assembly of AgsA and might take the role of an inhibitor for its chaperone-like activity at room temperature.
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Affiliation(s)
- Qiuhu Zhou
- Department of Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xue-Yuan Road, Beijing, 100191, People's Republic of China
| | - Xiaodong Shi
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, 221004, People's Republic of China
| | - Kaiming Zhang
- Department of Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xue-Yuan Road, Beijing, 100191, People's Republic of China
| | - Chao Shi
- Department of Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xue-Yuan Road, Beijing, 100191, People's Republic of China
| | - Lixin Huang
- Department of Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xue-Yuan Road, Beijing, 100191, People's Republic of China
| | - Zhenzhan Chang
- Department of Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xue-Yuan Road, Beijing, 100191, People's Republic of China.
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12
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Yang J, Zhou S, Guo M, Li Y, Gu J. Different alpha crystallin expression in human age-related and congenital cataract lens epithelium. BMC Ophthalmol 2016; 16:67. [PMID: 27234311 PMCID: PMC4884376 DOI: 10.1186/s12886-016-0241-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 05/19/2016] [Indexed: 11/24/2022] Open
Abstract
Background The purpose of this study was to investigate the different expressions of αA-crystallin and αB-crystallin in human lens epithelium of age-related and congenital cataracts. Methods The central part of the human anterior lens capsule approximately 5 mm in diameter together with the adhering epithelial cells, were harvested and processed within 6 hours after cataract surgery from age-related and congenital cataract patients or from normal eyes of fresh cadavers. The mRNA and soluble protein levels of αA-crystallin and αB-crystallin in the human lens epithelium were detected by real-time PCR and western blots, respectively. Results The mRNA and soluble protein expressions of αA-crystallin and αB-crystallin in the lens epithelium were both reduced in age-related and congenital cataract groups when compared with the normal control group. However, the degree of α-crystallin loss in the lens epithelium was highly correlated with different cataract types. The α-crystallin expression of the lens epithelium was greatly reduced in the congenital cataract group but only moderately decreased in the age-related cataract group. The reduction of αA-crystallin soluble protein levels in the congenital cataract group was approximately 2.4 fold decrease compared with that of the age-related cataract group, while an mRNA fold change of 1.67 decrease was observed for the age-related cataract group. Similarly, the reduction of soluble protein levels of αB-crystallin in the congenital cataract group was approximately a 1.57 fold change compared with that of the age-related cataract group. A 1.75 fold change for mRNA levels compared with that of the age-related cataract group was observed. Conclusions The results suggest that the differential loss of α-crystallin in the human lens epithelium could be associated with the different mechanisms of cataractogenesis in age-related versus congenital cataracts, subsequently resulting in different clinical presentations.
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Affiliation(s)
- Jing Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54S Xianlie, Guangzhou, Guangdong, 510060, People's Republic of China
| | - Sheng Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54S Xianlie, Guangzhou, Guangdong, 510060, People's Republic of China.,Department of ophthalmology, The First People's Hospital of Foshan, Guangdong Province, China
| | - Minfei Guo
- Department of Ophthalmology, Huichang County People's Hospital, Jiangxi, China
| | - Yuting Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54S Xianlie, Guangzhou, Guangdong, 510060, People's Republic of China
| | - Jianjun Gu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54S Xianlie, Guangzhou, Guangdong, 510060, People's Republic of China.
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13
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Anbarasu K, Sivakumar J. Multidimensional significance of crystallin protein-protein interactions and their implications in various human diseases. Biochim Biophys Acta Gen Subj 2015; 1860:222-33. [PMID: 26365509 DOI: 10.1016/j.bbagen.2015.09.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 08/28/2015] [Accepted: 09/08/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND Crystallins are the important structural and functional proteins in the eye lens responsible for refractive index. Post-translational modifications (PTMs) and mutations are major causative factors that affect crystallin structural conformation and functional characteristics thus playing a vital role in the etiology of cataractogenesis. SCOPE OF REVIEW The significance of crystallin protein-protein interactions (PPIs) in the lens and non-lenticular tissues is summarized. MAJOR CONCLUSIONS Aberrancy of PPIs between crystallin, its associated protein and metal ions has been accomplished in various human diseases including cataract. A detailed account on multidimensional structural and functional significance of crystallin PPI in humans must be brought into limelight, in order to understand the biochemical and molecular basis augmenting the aberrancies of such interaction. In this scenario, the present review is focused to shed light on studies which will aid to expand our present understanding on disease pathogenesis related to loss of PPI thereby paving the way for putative future therapeutic targets to curb such diseases. GENERAL SIGNIFICANCE The interactions with α-crystallins always aid to protect their structural and functional characteristics. The up-regulation of αB-crystallin in the non-lenticular tissues always decodes as biomarker for various stress related disorders. For better understanding and treatment of various diseases, PPI studies provide overall outline about the structural and functional characteristics of the proteins. This information not only helps to find out the route of cataractogenesis but also aid to identify potential molecules to inhibit/prevent the further development of such complicated phenomenon. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Kumarasamy Anbarasu
- Department of Marine Biotechnology, Bharathidasan University, Tiruchirapalli 620024, Tamil Nadu, India.
| | - Jeyarajan Sivakumar
- Department of Marine Biotechnology, Bharathidasan University, Tiruchirapalli 620024, Tamil Nadu, India
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14
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Ylikallio E, Konovalova S, Dhungana Y, Hilander T, Junna N, Partanen JV, Toppila JP, Auranen M, Tyynismaa H. Truncated HSPB1 causes axonal neuropathy and impairs tolerance to unfolded protein stress. BBA CLINICAL 2015; 3:233-42. [PMID: 26675522 PMCID: PMC4661565 DOI: 10.1016/j.bbacli.2015.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 02/28/2015] [Accepted: 03/03/2015] [Indexed: 11/26/2022]
Abstract
Background HSPB1 belongs to the family of small heat shock proteins (sHSP) that have importance in protection against unfolded protein stress, in cancer cells for escaping drug toxicity stress and in neurons for suppression of protein aggregates. sHSPs have a conserved α-crystalline domain (ACD), flanked by variable N- and C-termini, whose functions are not fully understood. Dominant missense variants in HSPB1, locating mostly to the ACD, have been linked to inherited neuropathy. Methods Patients underwent detailed clinical and neurophysiologic characterization. Disease causing variants were identified by exome or gene panel sequencing. Primary patient fibroblasts were used to investigate the effects of the dominant defective HSPB1 proteins. Results Frameshift variant predicting ablation of the entire C-terminus p.(Met169Cfs2*) of HSPB1 and a missense variant p.(Arg127Leu) were identified in patients with dominantly inherited motor-predominant axonal Charcot–Marie–Tooth neuropathy. We show that the truncated protein is stable and binds wild type HSPB1. Both mutations impaired the heat stress tolerance of the fibroblasts. This effect was particularly pronounced for the cells with the truncating variant, independent of heat-induced nuclear translocation and induction of global transcriptional heat response. Furthermore, the truncated HSPB1 increased cellular sensitivity to protein misfolding. Conclusion Our results suggest that truncation of the non-conserved C-terminus impairs the function of HSPB1 in cellular stress response. General significance sHSPs have important roles in prevention of protein aggregates that induce toxicity. We showed that C-terminal part of HSPB1 is critical for tolerance of unfolded protein stress, and when lacking causes axonal neuropathy in patients. C-terminal truncation of small heat shock protein HSPB1 causes neuropathy. Truncated HSPB1 is stable in patient fibroblasts and binds wild type HSPB1. C-terminus of HSPB1 is critical for tolerance to unfolded protein stress. Neuropathy may develop as a consequence of impaired cellular stress response.
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Key Words
- ACD, α-crystalline domain
- CADD, combined annotation dependent depletion
- CMT, Charcot–Marie–Tooth disease
- Charcot–Marie–Tooth neuropathy
- EMG, electromyography
- ENMG, electroneuromyography
- EVS, exome variant server
- HSPB1
- MUP, motor unit potential
- Protein misfolding
- QST, quantitative sensory testing
- SISu, Sequencing Initiative Suomi
- dHMN, distal hereditary motor neuropathy
- heat shock protein
- sHSP, small heat shock protein
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Affiliation(s)
- Emil Ylikallio
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Svetlana Konovalova
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Yogesh Dhungana
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Taru Hilander
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Nella Junna
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Juhani V Partanen
- Department of Clinical Neurophysiology, Medical Imaging Center, Helsinki University Central Hospital, Finland
| | - Jussi P Toppila
- Department of Clinical Neurophysiology, Medical Imaging Center, Helsinki University Central Hospital, Finland
| | - Mari Auranen
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland ; Department of Neurology, Helsinki University Central Hospital, Helsinki 00290, Finland
| | - Henna Tyynismaa
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland ; Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki 00290, Finland
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15
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Treweek TM, Meehan S, Ecroyd H, Carver JA. Small heat-shock proteins: important players in regulating cellular proteostasis. Cell Mol Life Sci 2015; 72:429-451. [PMID: 25352169 PMCID: PMC11113218 DOI: 10.1007/s00018-014-1754-5] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 09/15/2014] [Accepted: 10/01/2014] [Indexed: 12/13/2022]
Abstract
Small heat-shock proteins (sHsps) are a diverse family of intra-cellular molecular chaperone proteins that play a critical role in mitigating and preventing protein aggregation under stress conditions such as elevated temperature, oxidation and infection. In doing so, they assist in the maintenance of protein homeostasis (proteostasis) thereby avoiding the deleterious effects that result from loss of protein function and/or protein aggregation. The chaperone properties of sHsps are therefore employed extensively in many tissues to prevent the development of diseases associated with protein aggregation. Significant progress has been made of late in understanding the structure and chaperone mechanism of sHsps. In this review, we discuss some of these advances, with a focus on mammalian sHsp hetero-oligomerisation, the mechanism by which sHsps act as molecular chaperones to prevent both amorphous and fibrillar protein aggregation, and the role of post-translational modifications in sHsp chaperone function, particularly in the context of disease.
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Affiliation(s)
- Teresa M Treweek
- Graduate School of Medicine, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia.
| | - Sarah Meehan
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Heath Ecroyd
- Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia.
- School of Biological Sciences, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.
| | - John A Carver
- Research School of Chemistry, The Australian National University, Acton, ACT, 2601, Australia.
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16
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Kakkar V, Meister-Broekema M, Minoia M, Carra S, Kampinga HH. Barcoding heat shock proteins to human diseases: looking beyond the heat shock response. Dis Model Mech 2014; 7:421-34. [PMID: 24719117 PMCID: PMC3974453 DOI: 10.1242/dmm.014563] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
There are numerous human diseases that are associated with protein misfolding and the formation of toxic protein aggregates. Activating the heat shock response (HSR)--and thus generally restoring the disturbed protein homeostasis associated with such diseases--has often been suggested as a therapeutic strategy. However, most data on activating the HSR or its downstream targets in mouse models of diseases associated with aggregate formation have been rather disappointing. The human chaperonome consists of many more heat shock proteins (HSPs) that are not regulated by the HSR, however, and researchers are now focusing on these as potential therapeutic targets. In this Review, we summarize the existing literature on a set of aggregation diseases and propose that each of them can be characterized or 'barcoded' by a different set of HSPs that can rescue specific types of aggregation. Some of these 'non-canonical' HSPs have demonstrated effectiveness in vivo, in mouse models of protein-aggregation disease. Interestingly, several of these HSPs also cause diseases when mutated--so-called chaperonopathies--which are also discussed in this Review.
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Affiliation(s)
- Vaishali Kakkar
- University Medical Center Groningen, University of Groningen, Department of Cell Biology, A. Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Melanie Meister-Broekema
- University Medical Center Groningen, University of Groningen, Department of Cell Biology, A. Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Melania Minoia
- University Medical Center Groningen, University of Groningen, Department of Cell Biology, A. Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Serena Carra
- Università degli Studi di Modena e Reggio Emilia, Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, via G. Campi 287, 41125 Modena, Italy
| | - Harm H. Kampinga
- University Medical Center Groningen, University of Groningen, Department of Cell Biology, A. Deusinglaan 1, 9713 AV, Groningen, The Netherlands
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17
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Quinlan RA, Zhang Y, Lansbury A, Williamson I, Pohl E, Sun F. Changes in the quaternary structure and function of MjHSP16.5 attributable to deletion of the IXI motif and introduction of the substitution, R107G, in the α-crystallin domain. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120327. [PMID: 23530263 PMCID: PMC3638399 DOI: 10.1098/rstb.2012.0327] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The archael small heat-shock protein (sHSP), MjHSP16.5, forms a 24-subunit oligomer with octahedral symmetry. Here, we demonstrate that the IXI motif present in the C-terminal domain is necessary for the oligomerization of MjHSP16.5. Removal increased the in vitro chaperone activity with citrate synthase as the client protein. Less predictable were the effects of the R107G substitution in MjHSP16.5 because of the differences in the oligomerization of metazoan and non-metazoan sHSPs. We present the crystal structure for MjHSP16.5 R107G and compare this with an improved (2.5 Å) crystal structure for wild-type (WT) MjHSP16.5. Although no significant structural differences were found in the crystal, using cryo-electron microscopy, we identified two 24mer species with octahedral symmetry for the WT MjHSP16.5 both at room temperature and at 60°C, all showing two major species with the same diameter of 12.4 nm. Similarly, at room temperature, there are also two kinds of 12.4 nm oligomers for R107G MjHSP16.5, but in the 60°C sample, a larger 24mer species with a diameter of 13.6 nm was observed with significant changes in the fourfold symmetry axis and dimer–dimer interface. This highly conserved arginine, therefore, contributes to the quaternary organization of non-metazoan sHSP oligomers. Potentially, the R107G substitution has functional consequences as R107G MjHSP16.5 was far superior to the WT protein in protecting βL-crystallin against heat-induced aggregation.
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Affiliation(s)
- Roy A Quinlan
- Biophysical Sciences Institute, University of Durham, , South Road, Durham DH1 LE, UK
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18
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Hilton GR, Hochberg GKA, Laganowsky A, McGinnigle SI, Baldwin AJ, Benesch JLP. C-terminal interactions mediate the quaternary dynamics of αB-crystallin. Philos Trans R Soc Lond B Biol Sci 2013; 368:20110405. [PMID: 23530258 PMCID: PMC3638394 DOI: 10.1098/rstb.2011.0405] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
αB-crystallin is a highly dynamic, polydisperse small heat-shock protein that can form oligomers ranging in mass from 200 to 800 kDa. Here we use a multifaceted mass spectrometry approach to assess the role of the C-terminal tail in the self-assembly of αB-crystallin. Titration experiments allow us to monitor the binding of peptides representing the C-terminus to the αB-crystallin core domain, and observe individual affinities to both monomeric and dimeric forms. Notably, we find that binding the second peptide equivalent to the core domain dimer is considerably more difficult than the first, suggesting a role of the C-terminus in regulating assembly. This finding motivates us to examine the effect of point mutations in the C-terminus in the full-length protein, by quantifying the changes in oligomeric distribution and corresponding subunit exchange rates. Our results combine to demonstrate that alterations in the C-terminal tail have a significant impact on the thermodynamics and kinetics of αB-crystallin. Remarkably, we find that there is energy compensation between the inter- and intra-dimer interfaces: when one interaction is weakened, the other is strengthened. This allosteric communication between binding sites on αB-crystallin is likely important for its role in binding target proteins.
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Affiliation(s)
- Gillian R Hilton
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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19
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Elliott JL, Der Perng M, Prescott AR, Jansen KA, Koenderink GH, Quinlan RA. The specificity of the interaction between αB-crystallin and desmin filaments and its impact on filament aggregation and cell viability. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120375. [PMID: 23530264 PMCID: PMC3638400 DOI: 10.1098/rstb.2012.0375] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
CRYAB (αB-crystallin) is expressed in many tissues and yet the R120G mutation in CRYAB causes tissue-specific pathologies, namely cardiomyopathy and cataract. Here, we present evidence to demonstrate that there is a specific functional interaction of CRYAB with desmin intermediate filaments that predisposes myocytes to disease caused by the R120G mutation. We use a variety of biochemical and biophysical techniques to show that plant, animal and ascidian small heat-shock proteins (sHSPs) can interact with intermediate filaments. Nevertheless, the mutation R120G in CRYAB does specifically change that interaction when compared with equivalent substitutions in HSP27 (R140G) and into the Caenorhabditis elegans HSP16.2 (R95G). By transient transfection, we show that R120G CRYAB specifically promotes intermediate filament aggregation in MCF7 cells. The transient transfection of R120G CRYAB alone has no significant effect upon cell viability, although bundling of the endogenous intermediate filament network occurs and the mitochondria are concentrated into the perinuclear region. The combination of R120G CRYAB co-transfected with wild-type desmin, however, causes a significant reduction in cell viability. Therefore, we suggest that while there is an innate ability of sHSPs to interact with and to bind to intermediate filaments, it is the specific combination of desmin and CRYAB that compromises cell viability and this is potentially the key to the muscle pathology caused by the R120G CRYAB.
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Affiliation(s)
- Jayne L Elliott
- School of Biological and Biomedical Sciences, The University of Durham, South Road, Durham DH1 3LE, UK
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20
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Binding determinants of the small heat shock protein, αB-crystallin: recognition of the 'IxI' motif. EMBO J 2012. [PMID: 23188086 DOI: 10.1038/emboj.2012.318] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Small heat shock proteins (sHSPs) play a central role in protein homeostasis under conditions of stress by binding partly unfolded, aggregate-prone proteins and keeping them soluble. Like many sHSPs, the widely expressed human sHSP, αB-crystallin ('αB'), forms large polydisperse multimeric assemblies. Molecular interactions involved in both sHSP function and oligomer formation remain to be delineated. A growing database of structural information reveals that a central conserved α-crystallin domain (ACD) forms dimeric building blocks, while flanking N- and C-termini direct the formation of larger sHSP oligomers. The most commonly observed inter-subunit interaction involves a highly conserved C-terminal 'IxI/V' motif and a groove in the ACD that is also implicated in client binding. To investigate the inherent properties of this interaction, peptides mimicking the IxI/V motif of αB and other human sHSPs were tested for binding to dimeric αB-ACD. IxI-mimicking peptides bind the isolated ACD at 22°C in a manner similar to interactions observed in the oligomer at low temperature, confirming these interactions are likely to exist in functional αB oligomers.
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Clark AR, Lubsen NH, Slingsby C. sHSP in the eye lens: Crystallin mutations, cataract and proteostasis. Int J Biochem Cell Biol 2012; 44:1687-97. [DOI: 10.1016/j.biocel.2012.02.015] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/23/2012] [Indexed: 01/25/2023]
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Baldwin AJ, Walsh P, Hansen DF, Hilton GR, Benesch JLP, Sharpe S, Kay LE. Probing Dynamic Conformations of the High-Molecular-Weight αB-Crystallin Heat Shock Protein Ensemble by NMR Spectroscopy. J Am Chem Soc 2012; 134:15343-50. [DOI: 10.1021/ja307874r] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Andrew J. Baldwin
- Departments
of Molecular Genetics
and Chemistry, The University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department of Biochemistry, The University of Toronto, Toronto, Ontario M5S 1A8,
Canada
| | - Patrick Walsh
- Department of Biochemistry, The University of Toronto, Toronto, Ontario M5S 1A8,
Canada
- Program in Molecular
Structure, Hospital for Sick Children,
555 University Avenue,
Toronto, Ontario M5G 1X8, Canada
| | - D. Flemming Hansen
- Departments
of Molecular Genetics
and Chemistry, The University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Gillian R. Hilton
- Physical and Theoretical Chemistry
Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QZ, U.K
| | - Justin L. P. Benesch
- Physical and Theoretical Chemistry
Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, Oxfordshire OX1 3QZ, U.K
| | - Simon Sharpe
- Department of Biochemistry, The University of Toronto, Toronto, Ontario M5S 1A8,
Canada
- Program in Molecular
Structure, Hospital for Sick Children,
555 University Avenue,
Toronto, Ontario M5G 1X8, Canada
| | - Lewis E. Kay
- Departments
of Molecular Genetics
and Chemistry, The University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department of Biochemistry, The University of Toronto, Toronto, Ontario M5S 1A8,
Canada
- Program in Molecular
Structure, Hospital for Sick Children,
555 University Avenue,
Toronto, Ontario M5G 1X8, Canada
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Wu M, Zhang X, Bian Q, Taylor A, Liang JJ, Ding L, Horwitz J, Shang F. Oligomerization with wt αA- and αB-crystallins reduces proteasome-mediated degradation of C-terminally truncated αA-crystallin. Invest Ophthalmol Vis Sci 2012; 53:2541-50. [PMID: 22427585 DOI: 10.1167/iovs.11-9147] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We previously demonstrated that the ubiquitin-proteasome pathway (UPP) is a general protein quality control system that selectively degrades damaged or abnormal lens proteins, including C-terminally truncated αA-crystallin. The objective of this work was to determine the effects of wt αA- and αB-crystallins on the degradation of C-terminally truncated αA-crystallin (αA(1-162)) and vice versa. METHODS Recombinant wt αA, αB, and αA(1-162) were expressed in Escherichia coli and purified to homogeneity by chromatography. Subunit exchange and oligomerization were detected by fluorescence resonance energy transfer (FRET), multiangle-light scattering and coprecipitation assays. Protein substrates were labeled with (125)I and lens epithelial cell lysates were used as the source of the UPP for degradation assays. RESULTS FRET, multiangle light scattering, and coprecipitation assays showed that αA(1-162) exchanged subunits with wt αA- or wt αB- crystallin to form hetero-oligomers. αA(1-162) was more susceptible than wt αA-crystallin to degradation by the UPP. When mixed with wt αA-crystallin at 1:1 or 1:4 (αA(1-162) : wt) ratios to form hetero-oligomers, the degradation of αA(1-162) was significantly decreased. Conversely, formation of hetero-oligomers with αA(1-162) enhanced the degradation of wt αA-crystallin. The presence of αA(1-162), but not wt αA-crystallin, decreased the degradation of wt αB-crystallin. CONCLUSIONS αA(1-162) forms hetero-oligomers with wt αA- and αB-crystallins. Oligomerization with wt αA- or αB-crystallins reduces the susceptibility of αA(1-162) to degradation by the UPP. In addition, the presence of αA(1-162) in the hetero-oligomers also affects the degradation of wt αA- and αB-crystallins.
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Affiliation(s)
- Mingxing Wu
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington Street, Boston, MA 02111, USA.
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Posner M, Kiss AJ, Skiba J, Drossman A, Dolinska MB, Hejtmancik JF, Sergeev YV. Functional validation of hydrophobic adaptation to physiological temperature in the small heat shock protein αA-crystallin. PLoS One 2012; 7:e34438. [PMID: 22479631 PMCID: PMC3315530 DOI: 10.1371/journal.pone.0034438] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 03/02/2012] [Indexed: 02/02/2023] Open
Abstract
Small heat shock proteins (sHsps) maintain cellular homeostasis by preventing stress and disease-induced protein aggregation. While it is known that hydrophobicity impacts the ability of sHsps to bind aggregation-prone denaturing proteins, the complex quaternary structure of globular sHsps has made understanding the significance of specific changes in hydrophobicity difficult. Here we used recombinant protein of the lenticular sHsp α A-crystallin from six teleost fishes environmentally adapted to temperatures ranging from -2°C to 40°C to identify correlations between physiological temperature, protein stability and chaperone-like activity. Using sequence and structural modeling analysis we identified specific amino acid differences between the warm adapted zebrafish and cold adapted Antarctic toothfish that could contribute to these correlations and validated the functional consequences of three specific hydrophobicity-altering amino acid substitutions in αA-crystallin. Site directed mutagenesis of three residues in the zebrafish (V62T, C143S, T147V) confirmed that each impacts either protein stability or chaperone-like activity or both, with the V62T substitution having the greatest impact. Our results indicate a role for changing hydrophobicity in the thermal adaptation of α A-crystallin and suggest ways to produce sHsp variants with altered chaperone-like activity. These data also demonstrate that a comparative approach can provide new information about sHsp function and evolution.
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Affiliation(s)
- Mason Posner
- Department of Biology, Ashland University, Ashland, Ohio, United States of America.
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25
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Boncoraglio A, Minoia M, Carra S. The family of mammalian small heat shock proteins (HSPBs): implications in protein deposit diseases and motor neuropathies. Int J Biochem Cell Biol 2012; 44:1657-69. [PMID: 22484489 DOI: 10.1016/j.biocel.2012.03.011] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 03/20/2012] [Accepted: 03/20/2012] [Indexed: 12/19/2022]
Abstract
A number of neurological and muscular disorders are characterized by the accumulation of aggregate-prone proteins and are referred to as protein deposit or protein conformation diseases. Besides some sporadic forms, most of them are genetically inherited in an autosomal dominant manner, although recessive forms also exist. Although genetically very heterogeneous, some of these diseases are the result of mutations in some members of the mammalian small heat shock protein family (sHSP/HSPB), which are key players of the protein quality control system and participate, together with other molecular chaperones and co-chaperones, in the maintenance of protein homeostasis. Thus, on one hand upregulation of specific members of the HSPB family can exert protective effects in protein deposit diseases, such as the polyglutamine diseases. On the other hand, mutations in the HSPBs lead to neurological and muscular disorders, which may be due to a loss-of-function in protein quality control and/or to a gain-of-toxic function, resulting from the aggregation-proneness of the mutants. In this review we summarize the current knowledge about some of the best characterized functions of the HSPBs (e.g. role in cytoskeleton stabilization, chaperone function, anti-aggregation and anti-apoptotic activities), also highlighting differences in the properties of the various HSPBs and how these may counteract protein aggregation diseases. We also describe the mutations in the various HSPBs associated with neurological and muscular disorders and we discuss how gain-of-toxic function mechanisms (e.g. due to the mutated HSPB protein instability and aggregation) and/or loss-of-function mechanisms can contribute to HSPB-associated pathologies. This article is part of a Directed Issue entitled: Small HSPs in physiology and pathology.
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Affiliation(s)
- Alessandra Boncoraglio
- University Medical Center Groningen, Department of Cell Biology, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
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Hilton GR, Lioe H, Stengel F, Baldwin AJ, Benesch JLP. Small heat-shock proteins: paramedics of the cell. Top Curr Chem (Cham) 2012; 328:69-98. [PMID: 22576357 DOI: 10.1007/128_2012_324] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The small heat-shock proteins (sHSPs) comprise a family of molecular chaperones which are widespread but poorly understood. Despite considerable effort, comparatively few high-resolution structures have been determined for the sHSPs, a likely consequence of their tendency to populate ensembles of inter-converting conformational and oligomeric states at equilibrium. This dynamic structure appears to underpin the sHSPs' ability to bind and sequester target proteins rapidly, and renders them the first line of defence against protein aggregation during disease and cellular stress. Here we describe recent studies on the sHSPs, with a particular focus on those which have provided insight into the structure and dynamics of these proteins. The combined literature reveals a picture of a remarkable family of molecular chaperones whose thermodynamic and kinetic properties are exquisitely balanced to allow functional regulation by subtle changes in cellular conditions.
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Shang F, Taylor A. Role of the ubiquitin-proteasome in protein quality control and signaling: implication in the pathogenesis of eye diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 109:347-96. [PMID: 22727427 DOI: 10.1016/b978-0-12-397863-9.00010-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The ubiquitin-proteasome pathway (UPP) plays important roles in many cellular functions, such as protein quality control, cell cycle control, and signal transduction. The selective degradation of aberrant proteins by the UPP is essential for the timely removal of potential cytotoxic damaged or otherwise abnormal proteins. Conversely, accumulation of the cytotoxic abnormal proteins in eye tissues is etiologically associated with many age-related eye diseases such as retina degeneration, cataract, and certain types of glaucoma. Age- or stress-induced impairment or overburdening of the UPP appears to contribute to the accumulation of abnormal proteins in eye tissues. Cell cycle and signal transduction are regulated by the conditional UPP-dependent degradation of the regulators of these processes. Impairment or overburdening of the UPP could also result in dysregulation of cell cycle control and signal transduction. The consequences of the improper cell cycle and signal transduction include defects in ocular development, wound healing, angiogenesis, or inflammatory responses. Methods that enhance or preserve UPP function or reduce its burden may be useful strategies for preventing age-related eye diseases.
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Affiliation(s)
- Fu Shang
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Boston, Massachusetts, USA
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Houck SA, Landsbury A, Clark JI, Quinlan RA. Multiple sites in αB-crystallin modulate its interactions with desmin filaments assembled in vitro. PLoS One 2011; 6:e25859. [PMID: 22096479 PMCID: PMC3212511 DOI: 10.1371/journal.pone.0025859] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 09/13/2011] [Indexed: 12/02/2022] Open
Abstract
The β3- and β8-strands and C-terminal residues 155–165 of αB-crystallin were identified by pin arrays as interaction sites for various client proteins including the intermediate filament protein desmin. Here we present data using 5 well-characterised αB-crystallin protein constructs with substituted β3- and β8-strands and with the C-terminal residues 155–165 deleted to demonstrate the importance of these sequences to the interaction of αB-crystallin with desmin filaments. We used electron microscopy of negatively stained samples to visualize increased interactions followed by sedimentation assays to quantify our observations. A low-speed sedimentation assay measured the ability of αB-crystallin to prevent the self-association of desmin filaments. A high-speed sedimentation assay measured αB-crystallin cosedimentation with desmin filaments. Swapping the β8-strand of αB-crystallin or deleting residues 155–165 increased the cosedimentation of αB-crystallin with desmin filaments, but this coincided with increased filament-filament interactions. In contrast, substitution of the β3-strand with the equivalent αA-crystallin sequences improved the ability of αB-crystallin to prevent desmin filament-filament interactions with no significant change in its cosedimentation properties. These data suggest that all three sequences (β3-strand, β8-strand and C-terminal residues 155–165) contribute to the interaction of αB-crystallin with desmin filaments. The data also suggest that the cosedimentation of αB-crystallin with desmin filaments does not necessarily correlate with preventing desmin filament-filament interactions. This important observation is relevant not only to the formation of the protein aggregates that contain both desmin and αB-crystallin and typify desmin related myopathies, but also to the interaction of αB-crystallin with other filamentous protein polymers.
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Affiliation(s)
- Scott A. Houck
- Department of Biological Structure, University of Washington, Seattle, Washington, United States of America
| | - Andrew Landsbury
- School of Biological and Biomedical Sciences, University of Durham, Durham, United Kingdom
| | - John I. Clark
- Department of Biological Structure, University of Washington, Seattle, Washington, United States of America
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States of America
- * E-mail: (RAQ); (JIC)
| | - Roy A. Quinlan
- School of Biological and Biomedical Sciences, University of Durham, Durham, United Kingdom
- Biophysical Sciences Institute, University of Durham, Durham, United Kingdom
- * E-mail: (RAQ); (JIC)
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Baldwin AJ, Hilton GR, Lioe H, Bagnéris C, Benesch JL, Kay LE. Quaternary Dynamics of αB-Crystallin as a Direct Consequence of Localised Tertiary Fluctuations in the C-Terminus. J Mol Biol 2011; 413:310-20. [DOI: 10.1016/j.jmb.2011.07.017] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 07/08/2011] [Accepted: 07/11/2011] [Indexed: 11/16/2022]
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Pasupuleti N, Matsuyama S, Voss O, Doseff AI, Song K, Danielpour D, Nagaraj RH. The anti-apoptotic function of human αA-crystallin is directly related to its chaperone activity. Cell Death Dis 2011; 1:e31. [PMID: 21364639 PMCID: PMC3032290 DOI: 10.1038/cddis.2010.3] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
αA-crystallin is a molecular chaperone and an antiapoptotic protein. This study investigated the mechanism of inhibition of apoptosis by human αA-crystallin and determined if the chaperone activity of αA-crystallin is required for the antiapoptotic function. αA-crystallin inhibited chemical-induced apoptosis in Chinese hamster ovary (CHO) cells and HeLa cells by inhibiting activation of caspase-3 and -9. In CHO cells, it inhibited apoptosis induced by the overexpression of human proapoptotic proteins, Bim and Bax. αA-crystallin inhibited doxorubicin-mediated activation of human procaspase-3 in CHO cells and it activated the PI3K/Akt cell survival pathway by promoting the phosphorylation of PDK1, Akt and phosphatase tensin homologue in HeLa cells. The phosphoinositide 3 kinase (PI3K) activity was increased by αA-crystallin overexpression but the protein content was unaltered. Downregulation of PI3K by the expression of a dominant-negative mutant or inhibition by LY294002 abrogated the ability of αA-crystallin to phosphorylate Akt. These antiapoptotic functions of αA-crystallin were enhanced in a mutant protein (R21A) that shows increased chaperone activity than the wild-type (Wt) protein. Interestingly, a mutant protein (R49A) that shows decreased chaperone activity was far weaker than the Wt protein in its antiapoptotic functions. Together, our study results show that αA-crystallin inhibits apoptosis by enhancing PI3K activity and inactivating phosphatase tensin homologue and that the antiapoptotic function is directly related to its chaperone activity.
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Affiliation(s)
- N Pasupuleti
- Department of Ophthalmology and Visual Sciences, Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
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Raju M, Santhoshkumar P, Sharma KK. Cataract-causing αAG98R-crystallin mutant dissociates into monomers having chaperone activity. Mol Vis 2011; 17:7-15. [PMID: 21224997 PMCID: PMC3017799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 12/31/2010] [Indexed: 11/13/2022] Open
Abstract
PURPOSE The G98R mutation in αA-crystallin is associated with autosomal dominant cataract in humans. We have reported that mutant G98R protein has substrate-dependent chaperone activity. Further studies on this G98R mutant protein revealed that mutant protein shows reduced oligomeric stability and accelerated subunit dissociation at a low protein concentration. The purpose of present study was to investigate the chaperone function of dissociated subunits of αAG98R-crystallin. METHODS Substitution of glycine with arginine at position 98 in human αA-crystallin was accomplished by site-directed mutagenesis. The recombinant protein was expressed in E .coli cells and purified by chromatographic techniques. Purified αAG98R-crystallin was diluted to a concentration of 0.1 mg/ml in 50 mM phosphate buffer containing 150 mM NaCl (pH 7.2) and incubated at 37 °C for 24 h. The monomeric subunits were isolated from the oligomers through 50 kDa cutoff filters. The monomers were analyzed by SDS-PAGE, mass spectrometry, and circular dichroism spectroscopy and characterized by multi-angle light-scattering methods. Chaperone activity was tested against four client proteins: citrate synthesis, alcohol dehydrogenate, bovine βB2-crystallin and ovotransferrin. RESULTS Gel filtration studies showed that αAG98R-crystallin oligomers dissociate readily into monomers. Subunits of αAG98R-crystallin, isolated either by size exclusion chromatography or filtration showed chaperone activity against heat-denatured alcohol dehydrogenase, citrate synthase, bovine βB2-crystallin, and chemically denatured ovatransferrin. SDS-PAGE analysis of the mutant protein incubated at 37 °C for 12 days showed autolysis, which was confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS/MS) analysis of αAG98R-crystallin fragments recovered after SDS-PAGE. CONCLUSIONS The present study shows that the G98R mutation in αA-crystallin produces unstable oligomers that dissociate into active chaperone subunits. The chaperone activity of the dissociated subunits against four client proteins suggests that the αA-crystallin subunits are the minimal units of chaperone activity.
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Affiliation(s)
- Murugesan Raju
- Department of Ophthalmology, University of Missouri, Columbia, MO
| | | | - K. Krishna Sharma
- Department of Ophthalmology, University of Missouri, Columbia, MO,Department of Biochemistry, University of Missouri, Columbia, MO
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Ren S, Liu T, Jia C, Qi X, Wang Y. Physiological expression of lens α-, β-, and γ-crystallins in murine and human corneas. Mol Vis 2010; 16:2745-52. [PMID: 21179429 PMCID: PMC3003712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 12/09/2010] [Indexed: 11/24/2022] Open
Abstract
PURPOSE How corneal transparency is formed/maintained remains largely unclear. A group of enzymes which are referred to as enzymatic crystallins were proposed to contribute to corneal transparency in various animals. This study investigated whether the three classical lens crystallins, namely α-, β-, and γ-crystallins, exist in mouse and human corneas. METHODS Mice, human tissues, and cultured corneal cells were studied. The expression of lens crystallins in corneas or in cultured corneal cells were detected at the mRNA level by quantitative reverse transcription-PCR (QRT-PCR) and at the protein level by immunohistochemistry or western blotting. To check the effect of exogenous factor on expression of lens crystallins, cultured corneal cells were challenged with lipopolysaccharide or hydrogen peroxide and the expression of lens crystallins was monitored. RESULTS QRT-PCR revealed that the relative expression level of lens crystallins in C57BL/6 corneas were higher than in Balb/c corneas. Immunohistochemistry study showed that expression of αA-crystallin started from the embryonic stage, lasted untill old age, and was largely restricted to the epithelium or endothelium of the corneas. β- and γ-crystallins also were found in murine corneal epithelium. Upon treatment with lipopolysaccharide or hydrogen peroxide of cultured corneal epithelial cells, lens crystallins expression was significantly increased as detected by QRT-PCR or western blot assay. Further, both fetal corneal epithelial cultures and limbal stem cell cultures from adult human tissues were positive for lens crystallin immunofluorescence or immunohistochemistry staining. CONCLUSIONS Lens crystallins are expressed in mammalian corneas and cultured corneal cells. The expression levels depended on the animal strains or cell status. The physiologic and pathological significance of lens crystallins in corneas deserves more investigation.
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Forrest KML, Al-Sarraj S, Sewry C, Buk S, Tan SV, Pitt M, Durward A, McDougall M, Irving M, Hanna MG, Matthews E, Sarkozy A, Hudson J, Barresi R, Bushby K, Jungbluth H, Wraige E. Infantile onset myofibrillar myopathy due to recessive CRYAB mutations. Neuromuscul Disord 2010; 21:37-40. [PMID: 21130652 DOI: 10.1016/j.nmd.2010.11.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 10/14/2010] [Accepted: 11/11/2010] [Indexed: 01/27/2023]
Abstract
Mutations in the αB-crystallin (CRYAB) gene, encoding a small heat shock protein with chaperone function, are a rare cause of myofibrillar myopathy with autosomal-dominant inheritance, late-onset and moderate severity. We report a female infant presenting from 4 months with profound muscle stiffness, persistent creatine kinase elevation and electromyography characterized by spontaneous electrical activity and pseudomyotonic discharges. Muscle biopsy suggested a myofibrillar myopathy and genetic testing revealed homozygosity for the CRYAB mutation c.343delT (p.Ser115ProfsX14). These findings suggest a severe, recessively inherited form of CRYAB-related myofibrillar myopathy. Profound muscle stiffness as the main presenting feature indicates αB-crystallin as a potent modifier of muscle contractility.
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Affiliation(s)
- Katharine M L Forrest
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, London, UK
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Zhang H, Rajasekaran NS, Orosz A, Xiao X, Rechsteiner M, Benjamin IJ. Selective degradation of aggregate-prone CryAB mutants by HSPB1 is mediated by ubiquitin-proteasome pathways. J Mol Cell Cardiol 2010; 49:918-30. [PMID: 20863832 PMCID: PMC2975794 DOI: 10.1016/j.yjmcc.2010.09.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Revised: 09/01/2010] [Accepted: 09/01/2010] [Indexed: 11/12/2022]
Abstract
Disease-causing mutations of genes encoding small MW heat shock proteins (sHSPs) constitute a growing family of inherited myofibrillar disorders. In the present work, we found that three structurally-distinct CryAB mutants R120G, 450delA and 464delCT are mostly present in the detergent-insoluble fractions when overexpressed in H9c2 rat heart cells. We found that either over-expression or knockdown of HSPB1, a related sHSP, affects the solubility, stability, and degradation of aggregation-prone CryAB mutants. HSPB1 overexpression has negligible effects on the solubility and protein aggregates of either R120G and/or 450delA but increased the solubility and prevented formation of 464delCT aggregates. HSPB1 knockdown decreased solubility and increased protein aggregates of all CryAB mutants, indicating a key role for HSPB1 in clearance of CryAB mutants under basal conditions. We provide four lines of evidence that such selective clearance of R120G, 450delA and 464delCT mutants by HSPB1 is mediated by the ubiquitin-proteasome system (UPS). First, we found that treatment with the proteasome inhibitors increased the levels of all CryAB mutants. Second, R120G and 450delA overexpression corresponded to the accumulation of their specific ubiquitin conjugates in H9c2 cells. Third, HSPB1 knockdown directly increased the levels of all polyubiquitin conjugates. And fourth, the selective attenuation of 464delCT expression by HSPB1 over-expression was abrogated by the proteasome inhibition. We conclude that such selective interactions between CryAB mutants and HSPB1 overexpression might have important implications for the clinical manifestations and potential treatment.
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Affiliation(s)
- Huali Zhang
- Center for Cardiovascular Translational Biomedicine, Division of Cardiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Namakkal S. Rajasekaran
- Center for Cardiovascular Translational Biomedicine, Division of Cardiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Andras Orosz
- Center for Cardiovascular Translational Biomedicine, Division of Cardiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Xianzhong Xiao
- Department of Pathophysiology, Central South University, Changsha City, Hunan 41008, China
| | - Martin Rechsteiner
- Department of Biochemistry, University of Utah, School of Medicine, Salt Lake City, UT 84132, USA
| | - Ivor J. Benjamin
- Center for Cardiovascular Translational Biomedicine, Division of Cardiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- Department of Biochemistry, University of Utah, School of Medicine, Salt Lake City, UT 84132, USA
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Wu Y, MacRae TH. Truncation attenuates molecular chaperoning and apoptosis inhibition by p26, a small heat shock protein from Artemia franciscana. Biochem Cell Biol 2010; 88:937-46. [PMID: 21102656 DOI: 10.1139/o10-143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The small heat shock proteins (sHSPs), which prevent irreversible protein denaturation and inhibit apoptosis, consist of an amino-terminus, the canonical α-crystallin domain, and a carboxy-terminal extension. It remains difficult, however, to define sHSP structure-function relationships and with this in mind p26, an sHSP from the crustacean Artemia franciscana, was truncated by deletion mutagenesis. Wild-type p26 cDNA and three truncated variants inserted into the eukaryotic expression vector pcDNA3.1/HisC were used to generate stably transfected 293H cells. p26 shielded transfected cells against death upon exposure to heat and oxidative stress. Truncation reduced chaperone activity, with cells synthesizing the p26 α-crystallin domain being the least resistant. Wild-type p26 inhibited apoptosis in transfected cells, with protection against oxidation-generated apoptosis being more effective than that against heat-induced apoptosis. Truncation reduced p26 apoptotic inhibitory activity, with the α-crystallin domain again being the least effective. The results show that a crustacean sHSP functions effectively in mammalian cells, demonstrating interchangeability of these proteins between distantly related organisms and indicating similarities in their mechanisms of action. Moreover, maximal activity was observed for full-length p26, indicating that structural elements required for chaperone activity and apoptosis inhibition reside throughout the protein.
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Affiliation(s)
- Yong Wu
- Department of Biology, Dalhousie University, Halifax, NS, Canada
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Pasupuleti N, Gangadhariah M, Padmanabha S, Santhoshkumar P, Nagaraj RH. The role of the cysteine residue in the chaperone and anti-apoptotic functions of human Hsp27. J Cell Biochem 2010; 110:408-19. [PMID: 20225272 DOI: 10.1002/jcb.22552] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The small heat shock protein Hsp27 is a molecular chaperone and an anti-apoptotic protein. Human Hsp27 has one cysteine residue at position 137. We investigated the role of this cysteine residue in the chaperone and anti-apoptotic functions of Hsp27 by mutating the cysteine residue to an alanine (Hsp27(C137A)) and comparing it to wild-type protein (Hsp27(WT)). Both proteins were multi-subunit oligomers, but subunits of Hsp27(WT) were disulfide-linked unlike those of Hsp27(C137A), which were monomeric. Hsp27(C137A) was indistinguishable from Hsp27(WT) with regard to its secondary structure, surface hydrophobicity, oligomeric size and chaperone function. S-thiolation and reductive methylation of the cysteine residue had no apparent effect on the chaperone function of Hsp27(WT). The anti-apoptotic function of Hsp27(C137A) and Hsp27(WT) was studied by overexpressing them in CHO cells. No difference in the caspase-3 or -9 activity was observed in staurosporine-treated cells. The rate of apoptosis between Hsp27(C137A) and Hsp27(WT) overexpressing cells was similar whether the cells were treated with staurosporine or etoposide. However, the mutant protein was less protective relative to the wild-type protein in preventing caspase-3 and caspase-9 activation and apoptosis induced by 1 mM H(2)O(2) in CHO and HeLa cells. These data demonstrate that in human Hsp27, disulfide formation by the lone cysteine does not affect its chaperone function and anti-apoptotic function against chemical toxicants. However, oxidation of the lone cysteine in Hsp27 might at least partially affect the anti-apoptotic function against oxidative stress.
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Affiliation(s)
- Nagarekha Pasupuleti
- Department of Ophthalmology & Visual sciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Molecular chaperone alphaB-crystallin is expressed in the human fetal telencephalon at midgestation by a subset of progenitor cells. J Neuropathol Exp Neurol 2010; 69:745-59. [PMID: 20535031 DOI: 10.1097/nen.0b013e3181e5f515] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Alphab-crystallin (CRYAB) is a small heat shock protein with a chaperoning activity that is present in the postnatal healthy human brain in oligodendrocytes and in a few astrocytes. The involvement of CRYAB in cell differentiation, proliferation, signaling, cytoskeletal assembly, and apoptosis in various model systems has suggested that it might also play a role in the developing human brain. We analyzed the distribution and the levels of this molecular chaperone in healthy and polygenetically compromised (Down syndrome [DS]) human telencephalon at midgestation. We demonstrate that CRYAB is expressed in a temporospatial pattern by numerous radial glial cells and some early oligodendrocyte progenitors, including dividing cells, as well as a few astroglial cells in both healthy and DS fetal brains. We also found abundant phosphorylation of CRYAB at Ser-59, which mediates its antiapoptotic and cytoskeletal functions. There was only marginal phosphorylation at Ser-45.In contrast to our earlier study in young DS subjects, upregulation of phosphorylated CRYAB occurred rarely in DS fetuses. The distribution, the timing of appearance, and the results of colocalization studies suggest that CRYAB assists in the biological processes associated with developmental remodeling/differentiation and proliferation of select subpopulations of progenitor cells in human fetal brain at midgestation.
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Song S, Landsbury A, Dahm R, Liu Y, Zhang Q, Quinlan RA. Functions of the intermediate filament cytoskeleton in the eye lens. J Clin Invest 2009; 119:1837-48. [PMID: 19587458 DOI: 10.1172/jci38277] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Intermediate filaments (IFs) are a key component of the cytoskeleton in virtually all vertebrate cells, including those of the lens of the eye. IFs help integrate individual cells into their respective tissues. This Review focuses on the lens-specific IF proteins beaded filament structural proteins 1 and 2 (BFSP1 and BFSP2) and their role in lens physiology and disease. Evidence generated in studies in both mice and humans suggests a critical role for these proteins and their filamentous polymers in establishing the optical properties of the eye lens and in maintaining its transparency. For instance, mutations in both BFSP1 and BFSP2 cause cataract in humans. We also explore the potential role of BFSP1 and BFSP2 in aging processes in the lens.
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Affiliation(s)
- Shuhua Song
- Center for Ophthalmic Research/Surgery, Brigham and Women's Hospital, and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
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Sharma KK, Santhoshkumar P. Lens aging: effects of crystallins. Biochim Biophys Acta Gen Subj 2009; 1790:1095-108. [PMID: 19463898 DOI: 10.1016/j.bbagen.2009.05.008] [Citation(s) in RCA: 234] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 05/01/2009] [Accepted: 05/13/2009] [Indexed: 02/01/2023]
Abstract
The primary function of the eye lens is to focus light on the retina. The major proteins in the lens--alpha, beta, and gamma-crystallins--are constantly subjected to age-related changes such as oxidation, deamidation, truncation, glycation, and methylation. Such age-related modifications are cumulative and affect crystallin structure and function. With time, the modified crystallins aggregate, causing the lens to increasingly scatter light on the retina instead of focusing light on it and causing the lens to lose its transparency gradually and become opaque. Age-related lens opacity, or cataract, is the major cause of blindness worldwide. We review deamidation, and glycation that occur in the lenses during aging keeping in mind the structural and functional changes that these modifications bring about in the proteins. In addition, we review proteolysis and discuss recent observations on how crystallin fragments generated in vivo, through their anti-chaperone activity may cause crystallin aggregation in aging lenses. We also review hyperbaric oxygen treatment induced guinea pig and 'humanized' ascorbate transporting mouse models as suitable options for studies on age-related changes in lens proteins.
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Affiliation(s)
- K Krishna Sharma
- Department of Ophthalmology, University of Missouri-Columbia, 1 Hospital Drive, Columbia, MO 65212, USA.
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Grey AC, Schey KL. Age-related changes in the spatial distribution of human lens alpha-crystallin products by MALDI imaging mass spectrometry. Invest Ophthalmol Vis Sci 2009; 50:4319-29. [PMID: 19387068 DOI: 10.1167/iovs.09-3522] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To develop a protocol for MALDI (matrix-assisted laser desorption ionization) imaging mass spectrometry for mapping the distributions of alpha-crystallin and its modified forms in human lens tissue as a function of lens age and cataract. METHODS Frozen human lenses were cryosectioned equatorially and axially into 20-mum-thick sections, and the sections were mounted onto conductive glass slides by methanol soft-landing. An ethanol washing procedure facilitated uniform matrix crystal formation by a two-step matrix deposition procedure to produce high-quality mass spectral data. Molecular images of modified and unmodified alpha-crystallin subunits were obtained from mass spectral data acquired in 100-mum steps across normal and cataractous lens sections. Proteins extracted from the lens sections were digested with endoproteinase Glu-C and subjected to mass spectrometric analysis for identification of modifications. RESULTS Intact alpha-crystallin signals were detected primarily in the outer cortical fiber cells in lenses up to 29 years of age. Multiple truncation products were observed for alpha-crystallin that increased in abundance, both with distance into the lens and with lens age. Phosphorylated alphaB-crystallin forms were most abundant in the cortical region of older lenses. In axial sections, no significant anterior-posterior pole variation was observed. A previously unreported alphaA-crystallin mutation was detected in an age-matched cataractous human lens. CONCLUSIONS A method has been developed to spatially map the age-related changes of human lens alpha-crystallin by MALDI imaging mass spectrometry including a novel L52F alphaA-crystallin mutation in a cataractous lens. Application of this spatially resolved proteomic technique to lens biology enhances the understanding of alpha-crystallin protein processing in aging and diseased human lenses.
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Affiliation(s)
- Angus C Grey
- Department of Biochemistry, Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee 37232-8575, USA
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Jehle S, van Rossum B, Stout JR, Noguchi SM, Falber K, Rehbein K, Oschkinat H, Klevit RE, Rajagopal P. alphaB-crystallin: a hybrid solid-state/solution-state NMR investigation reveals structural aspects of the heterogeneous oligomer. J Mol Biol 2008; 385:1481-97. [PMID: 19041879 DOI: 10.1016/j.jmb.2008.10.097] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 09/24/2008] [Accepted: 10/29/2008] [Indexed: 10/21/2022]
Abstract
Atomic-level structural information on alphaB-Crystallin (alphaB), a prominent member of the small heat-shock protein family, has been a challenge to obtain due its polydisperse oligomeric nature. We show that magic-angle spinning solid-state NMR can be used to obtain high-resolution information on an approximately 580-kDa human alphaB assembled from 175-residue 20-kDa subunits. An approximately 100-residue alpha-crystallin domain is common to all small heat-shock proteins, and solution-state NMR was performed on two different alpha-crystallin domain constructs isolated from alphaB. In vitro, the chaperone-like activities of full-length alphaB and the isolated alpha-crystallin domain are identical. Chemical shifts of the backbone and C(beta) resonances have been obtained for residues 64-162 (alpha-crystallin domain plus part of the C-terminus) in alphaB and the isolated alpha-crystallin domain by solid-state and solution-state NMR, respectively. Both sets of data strongly predict six beta-strands in the alpha-crystallin domain. A majority of residues in the alpha-crystallin domain have similar chemical shifts in both solid-state and solution-state, indicating similar structures for the domain in its isolated and oligomeric forms. Sites of intersubunit interaction are identified from chemical shift differences that cluster to specific regions of the alpha-crystallin domain. Multiple signals are observed for the resonances of M68 in the oligomer, identifying the region containing this residue as existing in heterogeneous environments within alphaB. Evidence for a novel dimerization motif in the human alpha-crystallin domain is obtained by a comparison of (i) solid-state and solution-state chemical shift data and (ii) (1)H-(15)N heteronuclear single quantum coherence spectra as a function of pH. The isolated alpha-crystallin domain undergoes a dimer-monomer transition over the pH range 7.5-6.8. This steep pH-dependent switch may be important for alphaB to function optimally (e.g., to preserve the filament integrity of cardiac muscle proteins such as actin and desmin during cardiac ischemia, which is accompanied by acidosis).
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Murugesan R, Santhoshkumar P, Sharma KK. Role of alphaBI5 and alphaBT162 residues in subunit interaction during oligomerization of alphaB-crystallin. Mol Vis 2008; 14:1835-44. [PMID: 18941542 PMCID: PMC2568893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 10/03/2008] [Indexed: 11/15/2022] Open
Abstract
PURPOSE To determine whether the residues in the NH(2)- and COOH-terminal extensions interact with one another during oligomerization of alphaB-crystallin. METHODS Site-directed mutagenesis was used to mutate alphaBI5 and alphaBT162 residues to Cys. The recombinant I5C and T162C proteins were expressed in Escherichia coli cells and purified using chromatographic techniques. These proteins were analyzed by SDS-PAGE and mass spectrometry and characterized by multi-angle light scattering and circular dichroism (CD) spectroscopy methods. Fluorescence resonance energy transfer (FRET) assay was used to determine the interaction between the subunits. RESULTS Dimer formation was observed in both alphaBI5C and alphaBT162C in storage at 4 degrees C. During air oxidation at room temperature, alphaBT162C formed dimers to a greater extent than alphaBI5C. The average molar masses, secondary structures, and chaperone-like activities of the reduced forms of I5C and T162C were comparable to that of wild type alphaB-crystallin. The oligomeric assembly of reduced forms of I5C and T162C appeared homogenous under JEOL 1200EX Electron microscope whereas the oxidized proteins appeared as irregular aggregates. FRET assay demonstrated interactions between alphaBI5C-alphaBI5C and alphaBT162C-alphaBT162C. However, there was no evidence of an interaction between alphaBI5C and alphaBT162C residues during oligomerization. CONCLUSIONS This study suggests that residues from the NH(2)- and COOH-terminal regions in alphaB-crystallin interact with residues from the corresponding regions of another subunit, but there exists no interaction between the residues at the COOH-terminal extension region and the residues at the NH(2)-terminal region.
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