1
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Posner M, Garver T, Kaye T, Brdicka S, Suttle M, Patterson B, Farnsworth DR. Loss of αBa-crystallin, but not αA-crystallin, increases age-related cataract in the zebrafish lens. Exp Eye Res 2024; 244:109918. [PMID: 38705506 DOI: 10.1016/j.exer.2024.109918] [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: 02/13/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 05/07/2024]
Abstract
The vertebrate eye lens is an unusual organ in that most of its cells lack nuclei and the ability to replace aging protein. The small heat shock protein α-crystallins evolved to become key components of this lens, possibly because of their ability to prevent aggregation of aging protein that would otherwise lead to lens opacity. Most vertebrates express two α-crystallins, αA- and αB-crystallin, and mutations in each are linked to human cataract. In a mouse knockout model only the loss of αA-crystallin led to early-stage lens cataract. We have used the zebrafish as a model system to investigate the role of α-crystallins during lens development. Interestingly, while zebrafish express one lens-specific αA-crystallin gene (cryaa), they express two αB-crystallin genes, with one evolving lens specificity (cryaba) and the other retaining the broad expression of its mammalian ortholog (cryabb). In this study we used individual mutant zebrafish lines for all three α-crystallin genes to determine the impact of their loss on age-related cataract. Surprisingly, unlike mouse knockout models, we found that the loss of the αBa-crystallin gene cryaba led to an increase in lens opacity compared to cryaa null fish at 24 months of age. Loss of αA-crystallin did not increase the prevalence of cataract. We also used single cell RNA-Seq and RT-qPCR data to show a shift in the lens expression of zebrafish α-crystallins between 5 and 10 days post fertilization (dpf), with 5 and 6 dpf lenses expressing cryaa almost exclusively, and expression of cryaba and cryabb becoming more prominent after 10 dpf. These data show that cryaa is the primary α-crystallin during early lens development, while the protective role for cryaba becomes more important during lens aging. This study is the first to quantify cataract prevalence in wild-type aging zebrafish, showing that lens opacities develop in approximately 25% of fish by 18 months of age. None of the three α-crystallin mutants showed a compensatory increase in the expression of the remaining two crystallins, or in the abundant βB1-crystallin. Overall, these findings indicate an ontogenetic shift in the functional importance of individual α-crystallins during zebrafish lens development. Our finding that the lens-specific zebrafish αBa-crystallin plays the leading role in preventing age-related cataract adds a new twist to our understanding of vertebrate lens evolution.
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Affiliation(s)
- Mason Posner
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA.
| | - Taylor Garver
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Taylor Kaye
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Stuart Brdicka
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Madison Suttle
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Bryce Patterson
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Dylan R Farnsworth
- The RNA Institute, University at Albany, State University of New York, Albany, NY, USA
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2
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Peng X, Jia X, Shang G, Xue M, Jiang M, Chen D, Zhang F, Hu Y. The generation and characterization of a transgenic zebrafish line with lens-specific Cre expression. Mol Vis 2024; 30:123-136. [PMID: 38601019 PMCID: PMC11006009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 03/17/2024] [Indexed: 04/12/2024] Open
Abstract
Purpose Danio rerio zebrafish constitute a popular model for studying lens development and congenital cataracts. However, the specific deletion of a gene with a Cre/LoxP system in the zebrafish lens is unavailable because of the lack of a lens-Cre-transgenic zebrafish. This study aimed to generate a transgenic zebrafish line in which Cre recombinase was specifically expressed in the lens. Methods The pTol2 cryaa:Cre-polyA-cryaa:EGFP (enhanced green fluorescent protein) plasmid was constructed and co-injected with Tol2-transposase into one-to-two-cell-stage wild-type (WT) zebrafish embryos. Whole-mount in situ hybridization (ISH), tissue section, hematoxylin and eosin staining, a Western blot, a split-lamp observation, and a grid transmission assay were used to analyze the Cre expression, lens structure, and lens transparency of the transgenic zebrafish. Results In this study, we generated a transgenic zebrafish line, zTg(cryaa:Cre-cryaa:EGFP), in which Cre recombinase and EGFP were driven by the lens-specific cryaa promoter. zTg(cryaa:Cre-cryaa:EGFP) began to express Cre and EGFP specifically in the lens at the 22 hpf stage, and this ectopic Cre could efficiently and specifically delete the red fluorescent protein (RFP) signal from the lens when zTg(cryaa:Cre-cryaa:EGFP) embryos were injected with the loxP-flanked RFP plasmid. The overexpression of Cre and EGFP did not impair zebrafish development or lens transparency. Accordingly, this zTg(cryaa:Cre-cryaa:EGFP) zebrafish line is a useful tool for gene editing, specifically with zebrafish lenses. Conclusions We established a zTg(cryaa:Cre-cryaa:EGFP) zebrafish line that can specifically express an active Cre recombinase in lens tissues. This transgenic zebrafish line can be used as a tool to specifically manipulate a gene in zebrafish lenses.
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Affiliation(s)
- Xuyan Peng
- The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zheng Zhou, China
| | - Xiaolin Jia
- The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zheng Zhou, China
| | - Guohui Shang
- Department of Medical Genetics and Cell Biology, School of Basic Medical Sciences, Zhengzhou University, Zheng Zhou, China
| | - Mengjiao Xue
- The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zheng Zhou, China
| | - Mingjun Jiang
- The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zheng Zhou, China
| | - Dandan Chen
- The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zheng Zhou, China
| | - Fengyan Zhang
- The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zheng Zhou, China
| | - Yanzhong Hu
- The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, Zheng Zhou, China
- Joint National Laboratory for Antibody Drug Engineering, Henan University School of Basic Medical Sciences. Kaifeng, China
- Kaifeng Key Lab for Cataract and Myopia, Institute of Eye Disease, Kaifeng Central Hospital, Kaifeng, China
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3
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Posner M, Garver T, Kaye T, Brdicka S, Suttle M, Patterson B, Farnsworth DR. Loss of αBa-crystallin, but not αA-crystallin, increases age-related cataract in the zebrafish lens. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.03.574085. [PMID: 38260567 PMCID: PMC10802301 DOI: 10.1101/2024.01.03.574085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The vertebrate eye lens is an unusual organ in that most of its cells lack nuclei and the ability to replace aging protein. The small heat shock protein α-crystallins evolved to become key components of this lens, possibly because of their ability to prevent aggregation of aging protein that would otherwise lead to lens opacity. Most vertebrates express two α-crystallins, αA- and αB-crystallin, and mutations in each are linked to human cataract. In a mouse knockout model only the loss of αA-crystallin led to early-stage lens cataract. We have used the zebrafish as a model system to investigate the role of α-crystallins during lens development. Interestingly, while zebrafish express one lens-specific αA-crystallin gene (cryaa), they express two αB-crystallin genes, with one evolving lens specificity (cryaba) and the other retaining the broad expression of its mammalian ortholog (cryabb). In this study we used individual mutant zebrafish lines for all three α-crystallin genes to determine the impact of their loss on age-related cataract. Surprisingly, unlike mouse knockout models, we found that the loss of the αBa-crystallin gene cryaba led to an increase in lens opacity compared to cryaa null fish at 24 months of age. Loss of αA-crystallin did not increase the prevalence of cataract. We also used single cell RNA-Seq and RT-qPCR data to show a shift in the lens expression of zebrafish α-crystallins between 5 and 10 days post fertilization (dpf), with 5 and 6 dpf lenses expressing cryaa almost exclusively, and expression of cryaba and cryabb becoming more prominent after 10 dpf. These data show that cryaa is the primary α-crystallin during early lens development, while the protective role for cryaba becomes more important during lens aging. This study is the first to quantify cataract prevalence in wild-type zebrafish, showing that lens opacities develop in approximately 25% of fish by 18 months of age. None of the three α-crystallin mutants showed a compensatory increase in the expression of the remaining two crystallins, or in the abundant βB1-crystallin. Overall, these findings indicate an ontogenetic shift in the functional importance of individual α-crystallins during zebrafish lens development. Our finding that the lens-specific zebrafish αBa-crystallin plays the leading role in preventing age-related cataract adds a new twist to our understanding of vertebrate lens evolution.
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Affiliation(s)
- Mason Posner
- Department of Biology and Toxicology, Ashland University, Ashland, OH
| | - Taylor Garver
- Department of Biology and Toxicology, Ashland University, Ashland, OH
| | - Taylor Kaye
- Department of Biology and Toxicology, Ashland University, Ashland, OH
| | - Stuart Brdicka
- Department of Biology and Toxicology, Ashland University, Ashland, OH
| | - Madison Suttle
- Department of Biology and Toxicology, Ashland University, Ashland, OH
| | - Bryce Patterson
- Department of Biology and Toxicology, Ashland University, Ashland, OH
| | - Dylan R. Farnsworth
- The RNA InsRtute, University at Albany, State University of New York, Albany, NY
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4
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Park J, MacGavin S, Niederbrach L, Mchaourab HS. Interplay between Nrf2 and αB-crystallin in the lens and heart of zebrafish under proteostatic stress. Front Mol Biosci 2023; 10:1185704. [PMID: 37577747 PMCID: PMC10422029 DOI: 10.3389/fmolb.2023.1185704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 06/27/2023] [Indexed: 08/15/2023] Open
Abstract
A coordinated oxidative stress response, partly triggered by the transcription factor Nrf2, protects cells from the continual production of reactive oxygen species. Left unbuffered, reactive oxygen species can lead to protein aggregation that has been implicated in a spectrum of diseases such as cataract of the ocular lens and myopathy of the heart. While proteostasis is maintained by diverse families of heat shock proteins, the interplay between the oxidative and proteostatic stress responses in the lens and heart has not been investigated. Capitalizing on multiple zebrafish lines that have compromised function of Nrf2 and/or the two zebrafish small heat shock proteins αBa- and αBb-crystallin, we uncovered a transcriptional relationship that leads to a substantial increase in αBb-crystallin transcripts in the heart in response to compromised function of Nrf2. In the lens, the concomitant loss of function of Nrf2 and αBa-crystallin leads to upregulation of the cholesterol biosynthesis pathway, thus mitigating the phenotypic consequences of the αBa-crystallin knockout. By contrast, abrogation of Nrf2 function accentuates the penetrance of a heart edema phenotype characteristic of embryos of αB-crystallin knockout lines. Multiple molecular pathways, such as genes involved in extracellular interactions and implicated in cardiomyopathy, are revealed from transcriptome profiling, thus identifying novel targets for further investigation. Together, our transcriptome/phenotypic analysis establishes an intersection between oxidative stress and chaperone responses in the lens and heart.
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Affiliation(s)
| | | | | | - Hassane S. Mchaourab
- From the Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States
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5
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Posner M, Murray KL, Andrew B, Brdicka S, Roberts A, Franklin K, Hussen A, Kaye T, Kepp E, McDonald MS, Snodgrass T, Zientek K, David LL. Impact of α-crystallin protein loss on zebrafish lens development. Exp Eye Res 2023; 227:109358. [PMID: 36572168 PMCID: PMC9918708 DOI: 10.1016/j.exer.2022.109358] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/27/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
The α-crystallin small heat shock proteins contribute to the transparency and refractive properties of the vertebrate eye lens and prevent the protein aggregation that would otherwise produce lens cataracts, the leading cause of human blindness. There are conflicting data in the literature as to what role the α-crystallins may play in early lens development. In this study, we used CRISPR gene editing to produce zebrafish lines with mutations in each of the three α-crystallin genes (cryaa, cryaba and cryabb) to prevent protein production. The absence of each α-crystallin protein was analyzed by mass spectrometry, and lens phenotypes were assessed with differential interference contrast microscopy and histology. Loss of αA-crystallin produced a variety of lens defects with varying severity in larvae at 3 and 4 dpf but little substantial change in normal fiber cell denucleation. Loss of αBa-crystallin produced no substantial lens defects. Our cryabb mutant produced a truncated αBb-crystallin protein and showed no substantial change in lens development. Mutation of each α-crystallin gene did not alter the mRNA levels of the remaining two, suggesting a lack of genetic compensation. These data suggest that αA-crystallin plays some role in lens development, but the range of phenotype severity in null mutants indicates its loss simply increases the chance for defects and that the protein is not essential. Our finding that cryaba and cryabb mutants lack noticeable lens defects is congruent with insubstantial transcript levels for these genes in lens epithelial and fiber cells through five days of development. Future experiments can explore the molecular mechanisms leading to lens defects in cryaa null mutants and the impact of αA-crystallin loss during zebrafish lens aging.
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Affiliation(s)
- Mason Posner
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA.
| | - Kelly L Murray
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Brandon Andrew
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Stuart Brdicka
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Alexis Roberts
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Kirstan Franklin
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Adil Hussen
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Taylor Kaye
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Emmaline Kepp
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Mathew S McDonald
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Tyler Snodgrass
- Department of Biology and Toxicology, Ashland University, Ashland, OH, USA
| | - Keith Zientek
- Department of Chemical Physiology & Biochemistry, Oregon Health and Science University, USA
| | - Larry L David
- Department of Chemical Physiology & Biochemistry, Oregon Health and Science University, USA
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6
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Jia ZK, Fu CX, Wang AL, Yao K, Chen XJ. Cataract-causing allele in CRYAA (Y118D) proceeds through endoplasmic reticulum stress in mouse model. Zool Res 2021; 42:300-309. [PMID: 33929105 PMCID: PMC8175955 DOI: 10.24272/j.issn.2095-8137.2020.354] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
As small heat shock proteins, α-crystallins function as molecular chaperones and inhibit the misfolding and aggregation of β/γ-crystallins. Genetic mutations of CRYAA are associated with protein aggregation and cataract occurrence. One possible process underlying cataract formation is that endoplasmic reticulum stress (ERS) induces the unfolded protein response (UPR), leading to apoptosis. However, the pathogenic mechanism related to this remains unexplored. Here, we successfully constructed a cataract-causing CRYAA (Y118D) mutant mouse model, in which the lenses of the CRYAA-Y118D mutant mice showed severe posterior rupture, abnormal morphological changes, and aberrant arrangement of crystallin fibers. Histological analysis was consistent with the clinical pathological characteristics. We also explored the pathogenic factors involved in cataract development through transcriptome analysis. In addition, based on key pathway analysis, up-regulated genes in CRYAA-Y118D mutant mice were implicated in the ERS-UPR pathway. This study showed that prolonged activation of the UPR pathway and severe stress response can cause proteotoxic and ERS-induced cell death in CRYAA-Y118D mutant mice.
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Affiliation(s)
- Zhe-Kun Jia
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
| | - Chen-Xi Fu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
| | - Ai-Ling Wang
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310020, China
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China. E-mail:
| | - Xiang-Jun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310020, China. E-mail:
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7
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Sprague-Piercy MA, Rocha MA, Kwok AO, Martin RW. α-Crystallins in the Vertebrate Eye Lens: Complex Oligomers and Molecular Chaperones. Annu Rev Phys Chem 2021; 72:143-163. [PMID: 33321054 PMCID: PMC8062273 DOI: 10.1146/annurev-physchem-090419-121428] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
α-Crystallins are small heat-shock proteins that act as holdase chaperones. In humans, αA-crystallin is expressed only in the eye lens, while αB-crystallin is found in many tissues. α-Crystallins have a central domain flanked by flexible extensions and form dynamic, heterogeneous oligomers. Structural models show that both the C- and N-terminal extensions are important for controlling oligomerization through domain swapping. α-Crystallin prevents aggregation of damaged β- and γ-crystallins by binding to the client protein using a variety of binding modes. α-Crystallin chaperone activity can be compromised by mutation or posttranslational modifications, leading to protein aggregation and cataract. Because of their high solubility and their ability to form large, functional oligomers, α-crystallins are particularly amenable to structure determination by solid-state nuclear magnetic resonance (NMR) and solution NMR, as well as cryo-electron microscopy.
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Affiliation(s)
- Marc A Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, USA;
| | - Megan A Rocha
- Department of Chemistry, University of California, Irvine, California 92697, USA
| | - Ashley O Kwok
- Department of Chemistry, University of California, Irvine, California 92697, USA
| | - Rachel W Martin
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, USA;
- Department of Chemistry, University of California, Irvine, California 92697, USA
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8
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Ramirez LM, Shekhtman A, Pande J. Hydrophobic residues of melittin mediate its binding to αA-crystallin. Protein Sci 2019; 29:572-588. [PMID: 31762096 DOI: 10.1002/pro.3792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/13/2019] [Accepted: 11/15/2019] [Indexed: 01/01/2023]
Abstract
The molecular chaperone αA-crystallin, mainly localized in the human ocular lens, is believed to protect the lens from opacification and cataract, by suppressing the aggregation of the other lens proteins. The present study provides structural and thermodynamic insights into the ability of human αA-crystallin (HAA) to bind to its partially unfolded clients in the lens, using a small peptide, melittin from bee venom, as a model client. We characterized the thermodynamic parameters of the binding process between melittin and HAA through isothermal titration calorimetry (ITC), and found the binding to be endothermic and entropy-driven. We identified the amino acids in melittin important for binding to HAA by saturation-transfer difference (STD) nuclear magnetic resonance (NMR) experiments, and analysis of NMR line broadening upon titration of melittin with HAA. Our results suggest that hydrophobic residues Ile17 and Ile20 on the C-terminal region of melittin are in close contact with HAA in the melittin-HAA complex. Information obtained from NMR experiments was used to generate structural models of the melittin-HAA complex by molecular docking with high-ambiguity driven docking (HADDOCK). Structural models of the melittin-HAA complex reveal important principles underlying the interaction of HAA with its clients.
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Affiliation(s)
- Lisa M Ramirez
- Department of Chemistry, University at Albany, State University of New York, Albany, New York
| | - Alexander Shekhtman
- Department of Chemistry, University at Albany, State University of New York, Albany, New York
| | - Jayanti Pande
- Department of Chemistry, University at Albany, State University of New York, Albany, New York
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9
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Mishra S, Chandler SA, Williams D, Claxton DP, Koteiche HA, Stewart PL, Benesch JLP, Mchaourab HS. Engineering of a Polydisperse Small Heat-Shock Protein Reveals Conserved Motifs of Oligomer Plasticity. Structure 2018; 26:1116-1126.e4. [PMID: 29983375 DOI: 10.1016/j.str.2018.05.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 04/10/2018] [Accepted: 05/18/2018] [Indexed: 01/21/2023]
Abstract
Small heat-shock proteins (sHSPs) are molecular chaperones that bind partially and globally unfolded states of their client proteins. Previously, we discovered that the archaeal Hsp16.5, which forms ordered and symmetric 24-subunit oligomers, can be engineered to transition to an ordered and symmetric 48-subunit oligomer by insertion of a peptide from human HspB1 (Hsp27). Here, we uncovered the existence of an array of oligomeric states (30-38 subunits) that can be populated as a consequence of altering the sequence and length of the inserted peptide. Polydisperse Hsp16.5 oligomers displayed higher affinity to a model client protein consistent with a general mechanism for recognition and binding that involves increased access of the hydrophobic N-terminal region. Our findings, which integrate structural and functional analyses from evolutionarily distant sHSPs, support a model wherein the modular architecture of these proteins encodes motifs of oligomer polydispersity, dissociation, and expansion to achieve functional diversity and regulation.
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Affiliation(s)
- Sanjay Mishra
- Chemical & Physical Biology Program, Vanderbilt University, Nashville 37232, TN, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville 37232, TN, USA
| | - Shane A Chandler
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
| | - Dewight Williams
- John M. Cowley Center for High Resolution Electron Microscopy, Arizona State University, Tempe 85287, AZ, USA
| | - Derek P Claxton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville 37232, TN, USA
| | - Hanane A Koteiche
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville 37232, TN, USA
| | - Phoebe L Stewart
- Department of Pharmacology Case Western Reserve University, Cleveland, OH 44106, USA
| | | | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville 37232, TN, USA.
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10
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Posner M, Murray KL, McDonald MS, Eighinger H, Andrew B, Drossman A, Haley Z, Nussbaum J, David LL, Lampi KJ. The zebrafish as a model system for analyzing mammalian and native α-crystallin promoter function. PeerJ 2017; 5:e4093. [PMID: 29201567 PMCID: PMC5708185 DOI: 10.7717/peerj.4093] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 11/04/2017] [Indexed: 12/24/2022] Open
Abstract
Previous studies have used the zebrafish to investigate the biology of lens crystallin proteins and their roles in development and disease. However, little is known about zebrafish α-crystallin promoter function, how it compares to that of mammals, or whether mammalian α-crystallin promoter activity can be assessed using zebrafish embryos. We injected a variety of α-crystallin promoter fragments from each species combined with the coding sequence for green fluorescent protein (GFP) into zebrafish zygotes to determine the resulting spatiotemporal expression patterns in the developing embryo. We also measured mRNA levels and protein abundance for all three zebrafish α-crystallins. Our data showed that mouse and zebrafish αA-crystallin promoters generated similar GFP expression in the lens, but with earlier onset when using mouse promoters. Expression was also found in notochord and skeletal muscle in a smaller percentage of embryos. Mouse αB-crystallin promoter fragments drove GFP expression primarily in zebrafish skeletal muscle, with less common expression in notochord, lens, heart and in extraocular regions of the eye. A short fragment containing only a lens-specific enhancer region increased lens and notochord GFP expression while decreasing muscle expression, suggesting that the influence of mouse promoter control regions carries over into zebrafish embryos. The two paralogous zebrafish αB-crystallin promoters produced subtly different expression profiles, with the aBa promoter driving expression equally in notochord and skeletal muscle while the αBb promoter resulted primarily in skeletal muscle expression. Messenger RNA for zebrafish αA increased between 1 and 2 days post fertilization (dpf), αBa increased between 4 and 5 dpf, but αBb remained at baseline levels through 5 dpf. Parallel reaction monitoring (PRM) mass spectrometry was used to detect αA, aBa, and αBb peptides in digests of zebrafish embryos. In whole embryos, αA-crystallin was first detected by 2 dpf, peaked in abundance by 4–5 dpf, and was localized to the eye. αBa was detected in whole embryo at nearly constant levels from 1–6 dpf, was also localized primarily to the eye, and its abundance in extraocular tissues decreased from 4–7 dpf. In contrast, due to its low abundance, no αBb protein could be detected in whole embryo, or dissected eye and extraocular tissues. Our results show that mammalian α-crystallin promoters can be efficiently screened in zebrafish embryos and that their controlling regions are well conserved. An ontogenetic shift in zebrafish aBa-crystallin promoter activity provides an interesting system for examining the evolution and control of tissue specificity. Future studies that combine these promoter based approaches with the expanding ability to engineer the zebrafish genome via techniques such as CRISPR/Cas9 will allow the manipulation of protein expression to test hypotheses about lens crystallin function and its relation to lens biology and disease.
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Affiliation(s)
- Mason Posner
- Department of Biology/Toxicology, Ashland University, Ashland, OH, United States of America
| | - Kelly L Murray
- Department of Biology/Toxicology, Ashland University, Ashland, OH, United States of America
| | - Matthew S McDonald
- Department of Biology/Toxicology, Ashland University, Ashland, OH, United States of America
| | - Hayden Eighinger
- Department of Biology/Toxicology, Ashland University, Ashland, OH, United States of America
| | - Brandon Andrew
- Department of Biology/Toxicology, Ashland University, Ashland, OH, United States of America
| | - Amy Drossman
- Department of Biology/Toxicology, Ashland University, Ashland, OH, United States of America
| | - Zachary Haley
- Department of Biology/Toxicology, Ashland University, Ashland, OH, United States of America
| | - Justin Nussbaum
- Department of Biology, Lakeland Community College, Kirtland, OH, United States of America
| | - Larry L David
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, OR, United States of America
| | - Kirsten J Lampi
- Department of Integrative Biosciences, Oregon Health and Science University, Portland, OR, United States of America
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11
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Mishra S, Wu SY, Fuller AW, Wang Z, Rose KL, Schey KL, Mchaourab HS. Loss of αB-crystallin function in zebrafish reveals critical roles in the development of the lens and stress resistance of the heart. J Biol Chem 2017; 293:740-753. [PMID: 29162721 DOI: 10.1074/jbc.m117.808634] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/17/2017] [Indexed: 12/12/2022] Open
Abstract
Genetic mutations in the human small heat shock protein αB-crystallin have been implicated in autosomal cataracts and skeletal myopathies, including heart muscle diseases (cardiomyopathy). Although these mutations lead to modulation of their chaperone activity in vitro, the in vivo functions of αB-crystallin in the maintenance of both lens transparency and muscle integrity remain unclear. This lack of information has hindered a mechanistic understanding of these diseases. To better define the functional roles of αB-crystallin, we generated loss-of-function zebrafish mutant lines by utilizing the CRISPR/Cas9 system to specifically disrupt the two αB-crystallin genes, αBa and αBb We observed lens abnormalities in the mutant lines of both genes, and the penetrance of the lens phenotype was higher in αBa than αBb mutants. This finding is in contrast with the lack of a phenotype previously reported in αB-crystallin knock-out mice and suggests that the elevated chaperone activity of the two zebrafish orthologs is critical for lens development. Besides its key role in the lens, we uncovered another critical role for αB-crystallin in providing stress tolerance to the heart. The αB-crystallin mutants exhibited hypersusceptibility to develop pericardial edema when challenged by crowding stress or exposed to elevated cortisol stress, both of which activate glucocorticoid receptor signaling. Our work illuminates the involvement of αB-crystallin in stress tolerance of the heart presumably through the proteostasis network and reinforces the critical role of the chaperone activity of αB-crystallin in the maintenance of lens transparency.
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Affiliation(s)
- Sanjay Mishra
- From the Departments of Molecular Physiology and Biophysics and
| | - Shu-Yu Wu
- From the Departments of Molecular Physiology and Biophysics and
| | | | - Zhen Wang
- Biochemistry and.,Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Kristie L Rose
- Biochemistry and.,Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Kevin L Schey
- Biochemistry and.,Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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Mynampati BK, Muthukumarappa T, Ghosh S, Ram J. A silent mutation in human alpha-A crystallin gene in patients with age-related nuclear or cortical cataract. Bosn J Basic Med Sci 2017; 17:114-119. [PMID: 28146420 DOI: 10.17305/bjbms.2017.1745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 11/29/2016] [Accepted: 11/30/2016] [Indexed: 11/16/2022] Open
Abstract
A cataract is a complex multifactorial disease that results from alterations in the cellular architecture, i.e. lens proteins. Genes associated with the development of lens include crystallin genes. Although crystallins are highly conserved proteins among vertebrates, a significant number of polymorphisms exist in human population. In this study, we screened for polymorphisms in crystallin alpha A (CRYAA) and alpha B (CRYAB) genes in 200 patients over 40 years of age, diagnosed with age-related cataract (ARC; nuclear and cortical cataracts). Genomic DNA was extracted from the peripheral blood. The coding regions of the CRYAA and CRYAB gene were amplified using polymerase chain reaction and subjected to restriction digestion. Restriction fragment length polymorphism (RFLP) was performed using known restriction enzymes for CRYAA and CRYAB genes. Denaturing high performance liquid chromatography and direct sequencing were performed to detect sequence variation in CRYAA gene. In silico analysis of secondary CRYAA mRNA structure was performed using CLC RNA Workbench. RFLP analysis did not show any changes in the restriction sites of CRYAA and CRYAB genes. In 6 patients (4 patients with nuclear cataract and 2 with cortical cataract), sequence analysis of the exon 1 in the CRYAA gene showed a silent single nucleotide polymorphism [D2D] (CRYAA: C to T transition). One of the patients with nuclear cataract was homozygous for this allele. The in silico analysis revealed that D2D mutation results in a compact CRYAA mRNA secondary structure, while the wild type CRYAA mRNA has a weak or loose secondary structure. D2D mutation in the CRYAA gene may be an additional risk factor for progression of ARC.
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Affiliation(s)
- Bharani K Mynampati
- Department of Ophthalmology, Advanced Eye Centre, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India; Department of Ophthalmology, University of Florida, Jacksonville, Florida.
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Wu SY, Zou P, Fuller AW, Mishra S, Wang Z, Schey KL, Mchaourab HS. Expression of Cataract-linked γ-Crystallin Variants in Zebrafish Reveals a Proteostasis Network That Senses Protein Stability. J Biol Chem 2016; 291:25387-25397. [PMID: 27770023 DOI: 10.1074/jbc.m116.749606] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/21/2016] [Indexed: 11/06/2022] Open
Abstract
The refractivity and transparency of the ocular lens is dependent on the stability and solubility of the crystallins in the fiber cells. A number of mutations of lens crystallins have been associated with dominant cataracts in humans and mice. Of particular interest were γB- and γD-crystallin mutants linked to dominant cataracts in mouse models. Although thermodynamically destabilized and aggregation-prone, these mutants were found to have weak affinity to the resident chaperone α-crystallin in vitro To better understand the mechanism of the cataract phenotype, we transgenically expressed different γD-crystallin mutants in the zebrafish lens and observed a range of lens defects that arise primarily from the aggregation of the mutant proteins. Unlike mouse models, a strong correlation was observed between the severity and penetrance of the phenotype and the level of destabilization of the mutant. We interpret this result to reflect the presence of a proteostasis network that can "sense" protein stability. In the more destabilized mutants, the capacity of this network is overwhelmed, leading to the observed increase in phenotypic penetrance. Overexpression of αA-crystallin had no significant effects on the penetrance of lens defects, suggesting that its chaperone capacity is not limiting. Although consistent with the prevailing hypothesis that a chaperone network is required for lens transparency, our results suggest that αA-crystallin may not be efficient to inhibit aggregation of lens γ-crystallin. Furthermore, our work implicates additional inputs/factors in this underlying proteostasis network and demonstrates the utility of zebrafish as a platform to delineate mechanisms of cataract.
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Affiliation(s)
- Shu-Yu Wu
- From the Departments of Molecular Physiology and Biophysics and
| | - Ping Zou
- From the Departments of Molecular Physiology and Biophysics and
| | | | - Sanjay Mishra
- From the Departments of Molecular Physiology and Biophysics and
| | - Zhen Wang
- Biochemistry and.,the Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Kevin L Schey
- Biochemistry and.,the Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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