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Jia L, Sun Y. In Silico Prediction Method for Protein Asparagine Deamidation. Methods Mol Biol 2023; 2552:199-217. [PMID: 36346593 DOI: 10.1007/978-1-0716-2609-2_10] [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: 06/16/2023]
Abstract
In silico prediction methods were developed to predict protein asparagine (Asn) deamidation. The method is based on understanding deamidation mechanism on structural level with machine learning. Our structure-based method is more accurate than the sequence-based method which is still widely used in protein engineering process. In addition, molecular dynamics simulation was applied to study the time occupancy of nucleophilic attack distance, which is hypothesized as the most important step toward the rate-limiting succinimide intermediate formation. A more accurate prediction method for distinguishing potentially liable amino acid residues would allow their elimination or reduction as early as possible in the drug discovery process. It is possible that such quantitative protein structure-property relationship tools can also be applied to other protein hotspot predictions.
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Affiliation(s)
- Lei Jia
- Amgen Research, One Amgen Center Drive, Thousand Oaks, CA, USA.
| | - Yaxiong Sun
- Amgen Research, One Amgen Center Drive, Thousand Oaks, CA, USA
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2
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Joseph R, Robinson ML, Lambert L, Srivastava OP. Lens-specific βA3/A1-conditional knockout mice: Phenotypic characteristics and calpain activation causing protein degradation and insolubilization. PLoS One 2023; 18:e0281386. [PMID: 36989286 PMCID: PMC10057792 DOI: 10.1371/journal.pone.0281386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 01/21/2023] [Indexed: 03/30/2023] Open
Abstract
βA3/A1-crystallin is a lens structural protein that plays an important role in maintaining lens transparency via interactions with other crystallins. While the function of βA3/A1-crystallin in the retina is well studied, its functions in the lens, other than as a structural protein, remain unclear. In the current study, we generated the lens-specific βA3/A1-crystallin conditional knockout mouse (named βA3/A1ckO) and explored phenotypic changes and the function of the crystallin in the lens. The βA3/A1ckO mice showed congenital cataract at birth and exhibited truncation of lens proteins. Several truncated protein fragments were recovered as a pellet during a low-speed centrifugation (800 rpm, 70 x g) followed by a relatively higher speed centrifugation (5000 rpm, 2744 x g). Mass spectrometric analysis of pellets recovered following the two centrifugations showed that among the fragments with Mr < 20 kDa, the majority of these were from β-tubulin, and some from phakinin, αA-crystallin, and calpain-3. Further, we observed that in vitro activation of calpain-3 by calcium treatment of the wild-type-lens homogenate resulted in the degradation of calpain-3, αA-crystallin and β-tubulin and insolubilization of these proteins. Based on these results, it was concluded that the activation of calpain 3 resulted in proteolysis of β-tubulin, which disrupted cellular microtubular structure, and caused proteolysis of other lens proteins (αA-crystallin and phakinin). These proteolyzed protein fragments become insoluble, and together with the disruption of microtubular structure, and could be the causative factors in the development of congenital nuclear cataract in βA3/A1cKO mice.
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Affiliation(s)
- Roy Joseph
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, Alabama, United states of America
| | - Michael L Robinson
- Department of Biology, Miami University, Oxford, Ohio, United states of America
| | - Laura Lambert
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Om P Srivastava
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, Alabama, United states of America
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Timsina R, Wellisch S, Haemmerle D, Mainali L. Binding of Alpha-Crystallin to Cortical and Nuclear Lens Lipid Membranes Derived from a Single Lens. Int J Mol Sci 2022; 23:ijms231911295. [PMID: 36232595 PMCID: PMC9570235 DOI: 10.3390/ijms231911295] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/17/2022] [Accepted: 09/22/2022] [Indexed: 11/16/2022] Open
Abstract
Several studies reported that α-crystallin concentrations in the eye lens cytoplasm decrease with a corresponding increase in membrane-bound α-crystallin with age and cataracts. The influence of the lipid and cholesterol composition difference between cortical membrane (CM) and nuclear membrane (NM) on α-crystallin binding to membranes is still unclear. This study uses the electron paramagnetic resonance (EPR) spin-labeling method to investigate the α-crystallin binding to bovine CM and NM derived from the total lipids extracted from a single lens. Compared to CMs, NMs have a higher percentage of membrane surface occupied by α-crystallin and binding affinity, correlating with less mobility and more order below and on the surface of NMs. α-Crystallin binding to CM and NM decreases mobility with no significant change in order and hydrophobicity below and on the surface of membranes. Our results suggest that α-crystallin mainly binds on the surface of bovine CM and NM and such surface binding of α-crystallin to membranes in clear and young lenses may play a beneficial role in membrane stability. However, with decreased cholesterol content within the CM, which mimics the decreased cholesterol content in the cataractous lens membrane, α-crystallin binding increases the hydrophobicity below the membrane surface, indicating that α-crystallin binding forms a hydrophobic barrier for the passage of polar molecules, supporting the barrier hypothesis in developing cataracts.
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Affiliation(s)
- Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | | | - Dieter Haemmerle
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA
- Correspondence: ; Tel.: +1-(208)-426-4003
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Kashyap A, Gupta R. N-truncation in lipase Lip11 from Yarrowia lipolytica alleviates substrate inhibition with improved stability and efficiency ensuing distinct structural modifications. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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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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Timsina R, Mainali L. Association of Alpha-Crystallin with Fiber Cell Plasma Membrane of the Eye Lens Accompanied by Light Scattering and Cataract Formation. MEMBRANES 2021; 11:447. [PMID: 34203836 PMCID: PMC8232717 DOI: 10.3390/membranes11060447] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 02/04/2023]
Abstract
α-crystallin is a major protein found in the mammalian eye lens that works as a molecular chaperone by preventing the aggregation of proteins and providing tolerance to stress in the eye lens. These functions of α-crystallin are significant for maintaining lens transparency. However, with age and cataract formation, the concentration of α-crystallin in the eye lens cytoplasm decreases with a corresponding increase in the membrane-bound α-crystallin, accompanied by increased light scattering. The purpose of this review is to summarize previous and recent findings of the role of the: (1) lens membrane components, i.e., the major phospholipids (PLs) and sphingolipids, cholesterol (Chol), cholesterol bilayer domains (CBDs), and the integral membrane proteins aquaporin-0 (AQP0; formally MIP26) and connexins, and (2) α-crystallin mutations and post-translational modifications (PTMs) in the association of α-crystallin to the eye lens's fiber cell plasma membrane, providing thorough insights into a molecular basis of such an association. Furthermore, this review highlights the current knowledge and need for further studies to understand the fundamental molecular processes involved in the association of α-crystallin to the lens membrane, potentially leading to new avenues for preventing cataract formation and progression.
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Affiliation(s)
- Raju Timsina
- Department of Physics, Boise State University, Boise, ID 83725, USA;
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID 83725, USA;
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
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Abstract
The crystallins (α, β and γ), major constituent proteins of eye lens fiber cells play their critical role in maintaining the transparency and refractive index of the lens. Under different stress factors and with aging, β- and γ-crystallins start to unfold partially leading to their aggregation. Protein aggregation in lens basically enhances light scattering and causes the vision problem, commonly known as cataract. α-crystallin as a molecular chaperone forms complexes with its substrates (β- and γ-crystallins) to prevent such aggregation. In this chapter, the structural features of β- and γ-crystallins have been discussed. Detailed structural information linked with the high stability of γC-, γD- and γS-crystallins have been incorporated. The nature of homologous and heterologous interactions among crystallins has been deciphered, which are involved in their molecular association and complex formation.
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Affiliation(s)
- Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India.
| | - Priyanka Chauhan
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India
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Phadte AS, Mahalingam S, Santhoshkumar P, Sharma KK. Functional Rescue of Cataract-Causing αA-G98R-Crystallin by Targeted Compensatory Suppressor Mutations in Human αA-Crystallin. Biochemistry 2019; 58:4148-4158. [PMID: 31523965 DOI: 10.1021/acs.biochem.9b00374] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The G98R mutation in αA-crystallin is associated with the onset of presenile cataract and is characterized biochemically by an increased oligomeric mass, altered chaperone function, and loss of structural stability over time. Thus, far, it is not known whether the inherent instability caused by gain-of-charge mutation could be rescued by a compensatory loss of charge mutation elsewhere on the protein. To answer this question, we investigated whether αA-G98R-mediated instability could be rescued through suppressor mutations by introducing site-specific "compensatory" mutations in αA-G98R-crystallin, αA-R21Q/G98R, αA-G98R/R116C, and αA-R157Q/G98R. The recombinant proteins were expressed, purified, characterized, and evaluated by circular dichroism (CD), intrinsic fluorescence, and bis-ANS-binding studies. Chaperone-like activities of recombinant proteins were assessed using alcohol dehydrogenase (ADH) and insulin as unfolding substrates. Far-UV CD studies revealed an increased α-helical content in αA-G98R in comparison to αA-WT, αA-R21Q, R157Q, and the double mutants, αA-R21Q/G98R, and αA-R157Q/G98R. Compared to αA-WT, αA-R21Q, and αA-G98R, the double mutants showed an increased intrinsic tryptophan fluorescence, whereas the highest hydrophobicity (bis-ANS-binding) was shown by αA-G98R. Introduction of a second mutation in αA-G98R reduced its bis-ANS-binding activity. Both αA-R21Q/G98R and αA-R157Q/G98R showed greater chaperone-like activity against ADH aggregation than αA-G98R. However, among the three G98R mutants, only αA-R21Q/G98R protected ARPE-19 cells from H2O2-induced cytotoxicity. These results suggest that the lost chaperone-like activity of αA-G98R-crystallin can be rescued by another targeted mutation and that substitution of αA-R21Q-crystallin at the N-terminal region can rescue a deleterious mutation in the conserved α-crystallin domain of the protein.
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Affiliation(s)
- Ashutosh S Phadte
- Department of Ophthalmology , University of Missouri School of Medicine , Columbia , Missouri 65212 , United States.,Department of Biochemistry , University of Missouri , Columbia , Missouri 65212 , United States
| | - Sundararajan Mahalingam
- Department of Ophthalmology , University of Missouri School of Medicine , Columbia , Missouri 65212 , United States
| | - Puttur Santhoshkumar
- Department of Ophthalmology , University of Missouri School of Medicine , Columbia , Missouri 65212 , United States
| | - Krishna K Sharma
- Department of Ophthalmology , University of Missouri School of Medicine , Columbia , Missouri 65212 , United States.,Department of Biochemistry , University of Missouri , Columbia , Missouri 65212 , United States
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Abstract
Cataract is a major cause of blindness worldwide. It is characterized by lens opacification and is accompanied by extensive posttranslational modifications (PTMs) in various proteins. PTMs play an essential role in lens opacification. Several PTMs have been described in proteins isolated from relatively old human lenses, including phosphorylation, deamidation, racemization, truncation, acetylation, and methylation. An overwhelming majority of previous cataract proteomic studies have exclusively focused on crystallin proteins, which are the most abundant proteome components of the lens. To investigate the proteome of cataract markers, this chapter focuses on the proteomic research on the functional relevance of the major PTMs in crystallins of human cataractous lenses. Elucidating the role of these modifications in cataract formation has been a challenging task because they are among the most difficult PTMs to study analytically. The proteomic status of some amides presents similar properties in normal aged and cataractous lenses, whereas some may undergo greater PTMs in cataract. Therefore, it is of great importance to review the current proteomic research on crystallins, the major protein markers in different types of cataract, to elucidate the pathogenesis of this major human-blinding condition.
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Affiliation(s)
- Keke Zhang
- Eye Institute, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Department of Ophthalmology, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Key Laboratory of Myopia, Ministry of Health PR China, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xiangjia Zhu
- Eye Institute, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Department of Ophthalmology, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Key Laboratory of Myopia, Ministry of Health PR China, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yi Lu
- Eye Institute, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Department of Ophthalmology, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Key Laboratory of Myopia, Ministry of Health PR China, Shanghai, China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai Medical College, Fudan University, Shanghai, China
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Human alpha A-crystallin missing N-terminal domain poorly complexes with filensin and phakinin. Biochem Biophys Res Commun 2017; 494:402-408. [PMID: 28935373 DOI: 10.1016/j.bbrc.2017.09.088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 09/15/2017] [Indexed: 11/23/2022]
Abstract
The aim of this study was to determine relative importance of N-terminal domain and C-terminal extension of αA-crystallin during their in vitro complex formation with phakinin and filensin (the two lens-specific intermediate filament [IF] proteins). Cloned phakinin, filensin and vimentin were purified under a denaturing conditions by consecutive DEAE-cellulose-, hydroxyapatite- and Sephadex G-75-column chromatographic methods. WTαA-crystallin, αA-NT (N-terminal domain [residue number 1-63])-deleted and αA-CT (C-terminal terminal extension [residue number 140-173]-deleted), were cloned in pET 100 TOPO vector, expressed in BL-21 (DE3) cells using 1% IPTG, and purified using a Ni2+-affinity column. The following two in vitro methods were used to determine complex formation of WT-αA, αA-NT, or αA-CT with phakinin, filensin or both phakinin plus filensin together: an ultracentrifugation sedimentation (centrifugation at 80,000 × g for 30 min at 20 °C) followed by SDS-PAGE analysis, and an electron microscopic analysis. In the first method, the individual control proteins (WT-αA, αA-NT and αA-CT crystallin species) remained in the supernatant fractions whereas phakinin, filensin, and vimentin were recovered in the pellet fractions. On complex formation by individual WT-αA-, αA-NT or αA-CT-species with filensin, phakinin or both phakinin and filensin, WT-αA and αA-CT were recovered in the pellet fraction with phakinin, filensin or both filensin and phakinin, whereas αA-NT remained mostly in the supernatant, suggesting its poor complex formation property. EM-studies showed filamentous structure formation between WT-αA and αA-CT with phakinin or filensin, or with both filensin and phakinin together but relatively poor filamentous structures with αA-NT. Together, the results suggest that the N-terminal domain of αA-crystallin is required during in vitro complex formation with filensin and phakinin.
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11
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Jia L, Sun Y. Protein asparagine deamidation prediction based on structures with machine learning methods. PLoS One 2017; 12:e0181347. [PMID: 28732052 PMCID: PMC5521779 DOI: 10.1371/journal.pone.0181347] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 06/29/2017] [Indexed: 11/19/2022] Open
Abstract
Chemical stability is a major concern in the development of protein therapeutics due to its impact on both efficacy and safety. Protein "hotspots" are amino acid residues that are subject to various chemical modifications, including deamidation, isomerization, glycosylation, oxidation etc. A more accurate prediction method for potential hotspot residues would allow their elimination or reduction as early as possible in the drug discovery process. In this work, we focus on prediction models for asparagine (Asn) deamidation. Sequence-based prediction method simply identifies the NG motif (amino acid asparagine followed by a glycine) to be liable to deamidation. It still dominates deamidation evaluation process in most pharmaceutical setup due to its convenience. However, the simple sequence-based method is less accurate and often causes over-engineering a protein. We introduce structure-based prediction models by mining available experimental and structural data of deamidated proteins. Our training set contains 194 Asn residues from 25 proteins that all have available high-resolution crystal structures. Experimentally measured deamidation half-life of Asn in penta-peptides as well as 3D structure-based properties, such as solvent exposure, crystallographic B-factors, local secondary structure and dihedral angles etc., were used to train prediction models with several machine learning algorithms. The prediction tools were cross-validated as well as tested with an external test data set. The random forest model had high enrichment in ranking deamidated residues higher than non-deamidated residues while effectively eliminated false positive predictions. It is possible that such quantitative protein structure-function relationship tools can also be applied to other protein hotspot predictions. In addition, we extensively discussed metrics being used to evaluate the performance of predicting unbalanced data sets such as the deamidation case.
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Affiliation(s)
- Lei Jia
- Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA, United States of America
- * E-mail:
| | - Yaxiong Sun
- Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA, United States of America
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12
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Srivastava OP, Srivastava K, Chaves JM, Gill AK. Post-translationally modified human lens crystallin fragments show aggregation in vitro. Biochem Biophys Rep 2017; 10:94-131. [PMID: 28955739 PMCID: PMC5614626 DOI: 10.1016/j.bbrep.2017.01.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/23/2016] [Accepted: 01/26/2017] [Indexed: 10/25/2022] Open
Abstract
BACKGROUND Crystallin fragments are known to aggregate and cross-link that lead to cataract development. This study has been focused on determination of post-translational modifications (PTMs) of human lens crystallin fragments, and their aggregation properties. METHODS Four crystallin fragments-containing fractions (Fraction I [∼3.5 kDa species], Fraction II [∼3.5-7 kDa species], Fraction III [∼7-10 kDa species] and Fraction IV [>10-18 kDa species]), and water soluble high molecular weight (WS-HMW) protein fraction were isolated from water soluble (WS) protein fraction of human lenses of 50-70 year old-donors. The crystallin fragments of the Fractions I-IV were separated by two-dimensional (2D)-gel electrophoresis followed by analysis of their gel-spots by mass spectrometry. The Fractions I-IV were examined for their molecular mass, particle-diameters, amyloid fibril formation, and for their aggregation by themselves and with WS-HMW proteins. RESULTS Crystallin fragments in Fractions I-IV were derived from α-, β- and γ-crystallins, and their 2D-gel separated spots contained multiple crystallins with PTMs such as oxidation, deamidation, methylation and acetylation. Crystallin fragments from all the four fractions exhibited self-aggregated complexes ranging in Mr from 5.5×105 to 1.0×108 Da, with diameters of 10-28 nm, and amyloid fibril-like formation, and aggregation with WS-HMW proteins. CONCLUSION The crystallin fragments exhibited several PTMs, and were capable of forming aggregated species by themselves and with WS-HMW proteins, suggesting their potential role in aggregation process during cataract development. GENERAL SIGNIFICANCE Crystallin fragments play a major role in human cataract development.
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Affiliation(s)
- O P Srivastava
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - K Srivastava
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - J M Chaves
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - A K Gill
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
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Tikhomirova TS, Selivanova OM, Galzitskaya OV. α-Crystallins are small heat shock proteins: Functional and structural properties. BIOCHEMISTRY (MOSCOW) 2017; 82:106-121. [DOI: 10.1134/s0006297917020031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Thornell E, Aquilina A. Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis. Cell Mol Life Sci 2015; 72:4127-37. [PMID: 26210153 PMCID: PMC11113999 DOI: 10.1007/s00018-015-1996-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/10/2015] [Accepted: 07/16/2015] [Indexed: 11/27/2022]
Abstract
αA-Crystallin (αA) and αB-crystallin (αB) are small heat shock proteins responsible for the maintenance of transparency in the lens. In non-lenticular tissues, αB is involved in both maintenance of the cytoskeleton and suppression of neurodegeneration amongst other roles. Despite their importance in maintaining cellular health, modifications and mutations to αA and αB appear to play a role in disease states such as cataract and myopathies. The list of modifications that have been reported is extensive and include oxidation, disulphide bond formation, C- and N-terminal truncation, acetylation, carboxymethylation, carboxyethylation, carbamylation, deamidation, phosphorylation and methylation. Such modifications, notably phosphorylation, are alleged to cause changes to chaperone activity by inducing substructural changes and altering subunit exchange dynamics. Although the effect modification has on the activities of αA and αB is contentious, it has been proposed that these changes are responsible for the induction of hyperactivity and are thereby indirectly responsible for protein deposition characteristic of many diseases associated with αA and αB. This review compiles all reported sites of αA and αB modifications, and investigates the role phosphorylation, in particular, plays in cellular processes.
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Affiliation(s)
- Erin Thornell
- Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Ave., Wollongong, NSW, 2522, Australia.
| | - Andrew Aquilina
- Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Ave., Wollongong, NSW, 2522, Australia
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15
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Biophysical chemistry of the ageing eye lens. Biophys Rev 2015; 7:353-368. [PMID: 28510099 DOI: 10.1007/s12551-015-0176-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/23/2015] [Indexed: 12/24/2022] Open
Abstract
This review examines both recent and historical literature related to the biophysical chemistry of the proteins in the ageing eye, with a particular focus on cataract development. The lens is a vital component of the eye, acting as an optical focusing device to form clear images on the retina. The lens maintains the necessary high transparency and refractive index by expressing crystallin proteins in high concentration and eliminating all large cellular structures that may cause light scattering. This has the consequence of eliminating lens fibre cell metabolism and results in mature lens fibre cells having no mechanism for protein expression and a complete absence of protein recycling or turnover. As a result, the crystallins are some of the oldest proteins in the human body. Lack of protein repair or recycling means the lens tends to accumulate damage with age in the form of protein post-translational modifications. The crystallins can be subject to a wide range of age-related changes, including isomerisation, deamidation and racemisation. Many of these modification are highly correlated with cataract formation and represent a biochemical mechanism for age-related blindness.
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16
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Fujii N, Takata T, Fujii N, Aki K. Isomerization of aspartyl residues in crystallins and its influence upon cataract. Biochim Biophys Acta Gen Subj 2015; 1860:183-91. [PMID: 26275494 DOI: 10.1016/j.bbagen.2015.08.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 07/25/2015] [Accepted: 08/03/2015] [Indexed: 12/26/2022]
Abstract
BACKGROUND Age-related cataracts, which probably form due to insolubilization of lens proteins, can lead to loss of vision. Although the exact reason is unknown, lens protein aggregation may be triggered by increases in PTMs such as D-β-, L-β- and D-α-Asp isomers. These isomers have been observed in aged lens; however, there have been few quantitative and site-specific studies owing to the lack of a quick and precise method for distinguishing between D- and L-Asp in a peptide or protein. SCOPE OF REVIEW We describe a new method for detecting peptides containing Asp isomers at individual sites in any protein by using an LC-MS/MS system combined with commercial enzymes that specifically react with different isomers. We also summarize current data on the effect of Asp isomerization on lens crystallins. MAJOR CONCLUSIONS The new technique enabled the analysis of isomers of Asp residues in lens proteins precisely and quickly. An extensive proportion of Asp isomerization was observed at all Asp sites of crystallins in the insoluble fraction of aged lens. In addition, d-amino acid substitutions in crystallin-mimic peptides showed altered structural formation and function. These results indicate that isomerization of Asp residues affects the stability, structure and inter-subunit interaction of lens crystallins, which will induce crystallin aggregation and insolubilization, disrupt the associated functions, and ultimately contribute to the onset of senile cataract formation. GENERAL SIGNIFICANCE The mechanism underlying the onset of age-related diseases may involve isomerization, whereby D-amino acids are incorporated in the L-amino acid world of life. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Noriko Fujii
- Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494, Japan.
| | - Takumi Takata
- Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494, Japan
| | - Norihiko Fujii
- Radioisotope Research Center, Teikyo University, Kaga Itabashi-ku, Tokyo 173-8605, Japan
| | - Kenzo Aki
- Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, Kamiohno, Himeji 670-8524, Japan
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Pande A, Mokhor N, Pande J. Deamidation of Human γS-Crystallin Increases Attractive Protein Interactions: Implications for Cataract. Biochemistry 2015; 54:4890-9. [PMID: 26158710 DOI: 10.1021/acs.biochem.5b00185] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Deamidation of proteins is one of the most prevalent post-translational modifications found upon aging, and in age-onset diseases. Specific asparagine and glutamine residues are often selectively deamidated during this process. In the human lens, deamidation has been shown to occur in many crystallins, but it is not clear how these deamidated proteins lead to lens opacity or cataract. Here we have modeled in vitro the effect of deamidation of specific asparagine and glutamine residues in human recombinant γS-crystallin (HGS) on the solution properties of the protein. The residues selected for deamidation in vitro are those that are found to be deamidated in aged and cataractous lenses in vivo. Two derivatives were prepared, one with Asn76 and Asn143 deamidated (2N-HGS) and the other with two additional Gln residues (92 and 120) deamidated (2N2Q-HGS). Isoelectric focusing measurements showed the expected lowering of the pI from 6.9 in HGS to ∼6.5 in 2N-HGS and to ∼6.1 in 2N2Q-HGS. However, spectroscopic studies showed no significant change in the secondary and tertiary structures of the deamidated proteins relative to the wild type. The stability of 2N-HGS and 2N2Q-HGS, as measured by guanidinium hydrochloride unfolding, also remained comparable to that of HGS. The main difference was the altered protein-protein interaction among the three proteins. The net repulsive interactions that are characteristic of HGS are diminished in the deamidated derivatives as evidenced by static light scattering measurements of the second virial coefficient, B2 (B2 values for HGS, 2N-HGS, and 2N2Q-HGS of 8.90 × 10(-4), 7.10 × 10(-4), and 6.65 × 10(-4) mL mol g(-2), respectively). Further substantiation is provided by estimates of the excess binding energy of protein-protein interactions in the condensed phase, obtained from measurements of the PEG-induced liquid-liquid phase separation profiles for the three proteins. The data suggest that enhanced attractive protein-protein interactions, arising from the deamidation of HGS, promote protein aggregation, thereby leading to increased light scattering and opacity over time.
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Affiliation(s)
- Ajay Pande
- Department of Chemistry, Life Sciences 2070, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Natalya Mokhor
- Department of Chemistry, Life Sciences 2070, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Jayanti Pande
- Department of Chemistry, Life Sciences 2070, University at Albany, State University of New York, Albany, New York 12222, United States
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Raju M, Santhoshkumar P, Krishna Sharma K. Alpha-crystallin-derived peptides as therapeutic chaperones. Biochim Biophys Acta Gen Subj 2015; 1860:246-51. [PMID: 26141743 DOI: 10.1016/j.bbagen.2015.06.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/19/2015] [Accepted: 06/26/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND The demonstration of chaperone-like activity in peptides (mini-chaperones) derived from α-crystallin's chaperone region has generated significant interest in exploring the therapeutic potential of peptide chaperones in diseases of protein aggregation. Recent studies in experimental animals show that mini-chaperones could reach intended targets and alter the disease phenotype. Although mini-chaperones show potential benefits against protein aggregation diseases, they do tend to form aggregates on storage. There is thus a need to fine-tune peptide chaperones to increase their solubility, pharmacokinetics, and biological efficacy. SCOPE OF REVIEW This review summarizes the properties and the potential therapeutic roles of mini-chaperones in protein aggregation diseases and highlights some of the refinements needed to increase the stability and biological efficacy of mini-chaperones while maintaining or enhancing their chaperone-like activity against precipitation of unfolding proteins. MAJOR CONCLUSIONS Mini-chaperones suppress the aggregation of proteins, block amyloid fibril formation, stabilize mutant proteins, sequester metal ions, and exhibit antiapoptotic properties. Much work must be done to fine-tune mini-chaperones and increase their stability and biological efficacy. Peptide chaperones could have a great therapeutic value in diseases associated with protein aggregation and apoptosis. GENERAL SIGNIFICANCE Accumulation of misfolded proteins is a primary cause for many age-related diseases, including cataract, macular degeneration, and various neurological diseases. Stabilization of native proteins is a logical therapeutic approach for such diseases. Mini-chaperones, with their inherent antiaggregation and antiapoptotic properties, may represent an effective therapeutic molecule to prevent the cascade of protein conformational disorders. Future studies will further uncover the therapeutic potential of mini-chaperones. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Murugesan Raju
- Department of Ophthalmology, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Puttur Santhoshkumar
- Department of Ophthalmology, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - K Krishna Sharma
- Department of Ophthalmology, University of Missouri School of Medicine, Columbia, MO 65212, USA; Department of Biochemistry, University of Missouri School of Medicine, Columbia, MO 65212, USA.
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Haslbeck M, Peschek J, Buchner J, Weinkauf S. Structure and function of α-crystallins: Traversing from in vitro to in vivo. Biochim Biophys Acta Gen Subj 2015; 1860:149-66. [PMID: 26116912 DOI: 10.1016/j.bbagen.2015.06.008] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/10/2015] [Accepted: 06/22/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND The two α-crystallins (αA- and αB-crystallin) are major components of our eye lenses. Their key function there is to preserve lens transparency which is a challenging task as the protein turnover in the lens is low necessitating the stability and longevity of the constituent proteins. α-Crystallins are members of the small heat shock protein family. αB-crystallin is also expressed in other cell types. SCOPE OF THE REVIEW The review summarizes the current concepts on the polydisperse structure of the α-crystallin oligomer and its chaperone function with a focus on the inherent complexity and highlighting gaps between in vitro and in vivo studies. MAJOR CONCLUSIONS Both α-crystallins protect proteins from irreversible aggregation in a promiscuous manner. In maintaining eye lens transparency, they reduce the formation of light scattering particles and balance the interactions between lens crystallins. Important for these functions is their structural dynamics and heterogeneity as well as the regulation of these processes which we are beginning to understand. However, currently, it still remains elusive to which extent the in vitro observed properties of α-crystallins reflect the highly crowded situation in the lens. GENERAL SIGNIFICANCE Since α-crystallins play an important role in preventing cataract in the eye lens and in the development of diverse diseases, understanding their mechanism and substrate spectra is of importance. To bridge the gap between the concepts established in vitro and the in vivo function of α-crystallins, the joining of forces between different scientific disciplines and the combination of diverse techniques in hybrid approaches are necessary. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Martin Haslbeck
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching, Germany
| | - Jirka Peschek
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching, Germany
| | - Johannes Buchner
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching, Germany.
| | - Sevil Weinkauf
- Center for Integrated Protein Science at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching, Germany.
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Hariharapura R, Santhoshkumar P, Krishna Sharma K. Profiling of lens protease involved in generation of αA-66-80 crystallin peptide using an internally quenched protease substrate. Exp Eye Res 2013; 109:51-9. [PMID: 23410823 DOI: 10.1016/j.exer.2013.01.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/28/2013] [Accepted: 01/31/2013] [Indexed: 11/26/2022]
Abstract
Proteins of lens fiber cells are prone to accumulate extensive post-translational modifications because of very little protein turnover. Lens proteins are degraded via the lens proteolytic systems into peptides, which are subsequently hydrolyzed by downstream aminopeptidases. Inefficient degradation can lead to accumulation of protein fragments and subsequent aggregation. Previously we showed that αA-66-80 peptide and its truncated products accumulate in aging and cataract human lenses. These peptides interact with crystallins, causing crystallin aggregation and precipitation. N- and C-terminal-blocked peptides that have the cleavage sites to generate the αA-66-80 fragment were used to test lens extracts for sequence-specific proteases in lens extracts. An internally quenched fluorogenic peptide substrate containing the sequence-specific site for a lens protease to generate αA-66-80 peptide was designed, synthesized and used to characterize protease(s) that are capable of generating this peptide in bovine and human lenses. We show that proteases with the potential to generate αA-66-80 peptide are present in bovine and human lenses. We also show that the αA-66-80 peptides are resistant to hydrolysis by aminopeptidases present in the lenses and they can suppress the degradation of other peptides. Failure of complete hydrolysis of these peptides in vivo can lead to their accumulation in the lens and subsequent lens protein aggregation, which may ultimately lead to the formation of cataract.
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Affiliation(s)
- Raghu Hariharapura
- Department of Ophthalmology, University of Missouri-Columbia School of Medicine, Columbia, MO 65212, USA
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21
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Saccà SC, Roszkowska AM, Izzotti A. Environmental light and endogenous antioxidants as the main determinants of non-cancer ocular diseases. Mutat Res 2013; 752:153-171. [PMID: 23337404 DOI: 10.1016/j.mrrev.2013.01.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 01/10/2013] [Accepted: 01/11/2013] [Indexed: 02/03/2023]
Abstract
The human eye is constantly exposed to sunlight and artificial lighting. Exogenous sources of reactive oxygen species (ROS) such as UV light, visible light, ionizing radiation, chemotherapeutics, and environmental toxins contribute to oxidative damage in ocular tissues. Long-term exposure to these insults places the aging eye at considerable risk for pathological consequences of oxidative stress. Furthermore, in eye tissues, mitochondria are an important endogenous source of ROS. Over time, all ocular structures, from the tear film to the retina, undergo oxidative stress, and therefore, the antioxidant defenses of each tissue assume the role of a safeguard against degenerative ocular pathologies. The ocular surface and cornea protect the other ocular tissues and are significantly exposed to oxidative stress of environmental origin. Overwhelming of antioxidant defenses in these tissues clinically manifests as pathologies including pterygium, corneal dystrophies, and endothelial Fuch's dystrophy. The crystalline lens is highly susceptible to oxidative damage in aging because its cells and their intracellular proteins are not turned over or replaced, thus providing the basis for cataractogenesis. The trabecular meshwork, which is the anterior chamber tissue devoted to aqueous humor drainage, has a particular susceptibility to mitochondrial oxidative injury that affects its endothelium and leads to an intraocular pressure increase that marks the beginning of glaucoma. Photo-oxidative stress can cause acute or chronic retinal damage. The pathogenesis of age-related macular degeneration involves oxidative stress and death of the retinal pigment epithelium followed by death of the overlying photoreceptors. Accordingly, converging evidence indicates that mutagenic mechanisms of environmental and endogenous sources play a fundamental pathogenic role in degenerative eye diseases.
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Affiliation(s)
- Sergio C Saccà
- Department of Head/Neck Pathologies, St Martino Hospital, Ophthalmology unit, Genoa, Italy
| | - Anna Maria Roszkowska
- Department of Specialized Surgery, University Hospital, Ophthalmology Unit, Messina, Italy
| | - Alberto Izzotti
- Department of Health Sciences, University of Genoa, Via A. Pastore 1, I-16132, Genoa, Italy.
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22
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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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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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24
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Gupta R, Asomugha CO, Srivastava OP. The common modification in alphaA-crystallin in the lens, N101D, is associated with increased opacity in a mouse model. J Biol Chem 2011; 286:11579-92. [PMID: 21245144 PMCID: PMC3064212 DOI: 10.1074/jbc.m110.148627] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 01/10/2011] [Indexed: 11/06/2022] Open
Abstract
To elucidate the morphological and cellular changes due to introduction of a charge during development and the possible mechanism that underlies cataract development in humans as a consequence of an additional charge, we generated a transgenic mouse model mimicking deamidation of Asn at position 101. The mouse model expresses a human αA-crystallin gene in which Asn-101 was replaced with Asp, which is referred to as αAN101D-transgene and is considered to be "deamidated" in this study. Mice expressing αAN101D-transgene are referred to here CRYAA(N101D) mice. All of the lines showed the expression of αAN101D-transgene. Compared with the lenses of mice expressing wild-type (WT) αA-transgene (referred to as CRYAA(WT) mice), the lenses of CRYAA(N101D) mice showed (a) altered αA-crystallin membrane protein (aquaporin-0 (AQP0), a specific lens membrane protein) interaction, (b) extracellular spaces between outer cortical fiber cells, (c) attenuated denucleation during confocal microscopic examination, (d) disrupted normal fiber cell organization and structure during scanning electron microscopic examination, (e) distorted posterior suture lines by bright field microscopy, and (f) development of a mild anterior lens opacity in the superior cortical region during the optical coherence tomography scan analysis. Relative to lenses with WT αA-crystallin, the lenses containing the deamidated αA-crystallin also showed an aggregation of αA-crystallin and a higher level of water-insoluble proteins, suggesting that the morphological and cellular changes in these lenses are due to the N101D mutation. This study provides evidence for the first time that expression of deamidated αA-crystallin caused disruption of fiber cell structural integrity, protein aggregation, insolubilization, and mild cortical lens opacity.
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Affiliation(s)
- Ratna Gupta
- From the Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294-4390
| | - Chinwe O. Asomugha
- From the Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294-4390
| | - Om P. Srivastava
- From the Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294-4390
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25
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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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26
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León R, Murray JI, Cragg G, Farnell B, West NR, Pace TCS, Watson PH, Bohne C, Boulanger MJ, Hof F. Identification and Characterization of Binding Sites on S100A7, a Participant in Cancer and Inflammation Pathways. Biochemistry 2009; 48:10591-600. [DOI: 10.1021/bi901330g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Rafael León
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
| | - Jill I. Murray
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
| | - Gina Cragg
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
| | - Benjamin Farnell
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
| | - Nathan R. West
- Deeley Research Centre, BC Cancer Agency, 2410 Lee Avenue, Victoria, British Columbia V8R 6V5, Canada
| | - Tamara C. S. Pace
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
| | - Peter H. Watson
- Deeley Research Centre, BC Cancer Agency, 2410 Lee Avenue, Victoria, British Columbia V8R 6V5, Canada
| | - Cornelia Bohne
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
| | - Martin J. Boulanger
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
| | - Fraser Hof
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, British Columbia V8W 3V6, Canada
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Srivastava K, Gupta R, Chaves JM, Srivastava OP. Truncated human betaB1-crystallin shows altered structural properties and interaction with human betaA3-crystallin. Biochemistry 2009; 48:7179-89. [PMID: 19548648 PMCID: PMC2778247 DOI: 10.1021/bi900313c] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of the study was to determine the effects of truncation of various regions of betaB1-crystallin on its structural properties and stability of heterooligomers formed by wild-type (WT) betaB1 or its deletion mutants with WT betaA3-crystallin. For these analyses, seven deletion mutants of betaB1-crystallin were generated with the following sequential deletions of either N-terminal arm [betaB1(59-252)], N-terminal arm + motif I [betaB1(99-252)], N-terminal arm + motif I + motif II [betaB1(144-252)], N-terminal arm + motif I + motif II + connecting peptide [betaB1(149-252)], C-terminal extension [betaB1(1-234)], C-terminal extension plus motif IV [betaB1(1-190)], or C-terminal extension + motif III + motif IV [betaB1(1-148)]. The betaB1-crystallin became water insoluble on the deletion of C-terminal extension and subsequent deletions of the C-terminal domain (C-terminal extension plus motifs III and IV) while it remained partially soluble on the deletion of the N-terminal domain (N-terminal arm plus motifs I and II). However, circular dichroism spectral analysis showed that the deletion of the N-terminal domain but not the C-terminal domain exhibited relatively greater structural changes in the crystallin. The deletion of the C-terminal domain resulted in a greater exposure and disturbance in the microenvironment of Trp-100, Trp-123, and Trp-126 (localized in the motif II), suggesting a relatively greater role of the C-terminal domain than the N-terminal domain in the structural stability of the crystallin. The deletion of the N-terminal extension in betaB1 resulted in maximum exposure of hydrophobic patches and compact structure and in a maximum loss of subunit exchange with WT betaA3-crystallin compared to deletion of either the C-terminal extension, the N-terminal domain, or the C-terminal domain. The thermal stability results of the heterooligomer of betaB1- plus betaA3-crystallins suggested that oligomers lose their stability on deletion of the C-terminal domain. Together, the results suggested that the N-terminal arm of betaB1-crystallin plays a major role in interaction with betaA3-crystallin during heterooligomer formation, and the solubility of betaB1-crystallin per se and that of the heterooligomer with betaA3-crystallin are dependent on the intact C-terminal domain of betaB1-crystallin.
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Affiliation(s)
- K Srivastava
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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28
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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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