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Karakosta C, Samiotaki M, Panayotou G, Papaconstantinou DS, Moschos MM. Lens Cytoskeleton: An Update on the Etiopathogenesis of Human Cataracts. Cureus 2024; 16:e56793. [PMID: 38650819 PMCID: PMC11035009 DOI: 10.7759/cureus.56793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2024] [Indexed: 04/25/2024] Open
Abstract
A cataract is a loss of the transparency of a normal crystalline lens. Multiple factors, including age as the major risk factor for cataracts, can disturb the transparency of the crystalline lens due to cumulative damage from environmental insults to proteins, particularly crystallins. Lens proteins do not turnover, and crystallins undergo extensive post-translational modifications (PTMs) with age in order to interact with each other and maintain their soluble basis for lens transparency. These PTMs include truncation, oxidation, deamidation, acetylation, phosphorylation, and glycosylation. Cataract formation, apart from protein PTMs, involves protein crosslinking, protein insolubilization, and aggregation. Oxidation is a key feature in age-related cataract formation. Due to the role of genetic and environmental factors, as well as its variable clinical presentation, we consider cataracts to be a multifactorial disease. The preliminary results of our study indicate that proteins implicated in the pathway of a structural constituent of the eye lens (BFSP1, BFSP2, CRYAA, CRYAB, CRYBA, CRYBB, CRYGC, CRYGD, CRYGS, KRTs, and VIM), together with AQP1 and AQP5, may also be involved in lens aging.
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Affiliation(s)
- Christina Karakosta
- Ophthalmology, National and Kapodistrian University of Athens School of Medicine, Athens, GRC
| | - Martina Samiotaki
- Proteomics, Biomedical Sciences Research Center "Alexander Fleming", Athens, GRC
| | - George Panayotou
- Proteomics, Biomedical Sciences Research Center "Alexander Fleming", Athens, GRC
| | - Dimitrios S Papaconstantinou
- Ophthalmology, Gennimatas Hospital, National and Kapodistrian University of Athens School of Medicine, Athens, GRC
| | - Marilita M Moschos
- 1st Department of Ophthalmology, National and Kapodistrian University of Athens, Athens, GRC
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Delas F, Koller S, Feil S, Dacheva I, Gerth-Kahlert C, Berger W. Novel CRYGC Mutation in Conserved Ultraviolet-Protective Tryptophan (p.Trp131Arg) Is Linked to Autosomal Dominant Congenital Cataract. Int J Mol Sci 2023; 24:16594. [PMID: 38068917 PMCID: PMC10706789 DOI: 10.3390/ijms242316594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 10/13/2023] [Accepted: 11/14/2023] [Indexed: 12/18/2023] Open
Abstract
Congenital cataract (CC), the most prevalent cause of childhood blindness and amblyopia, necessitates prompt and precise genetic diagnosis. The objective of this study is to identify the underlying genetic cause in a Swiss patient with isolated CC. Whole exome sequencing (WES) and copy number variation (CNV) analysis were conducted for variant identification in a patient born with a total binocular CC without a family history of CC. Sanger Sequencing was used to confirm the variant and segregation analysis was used to screen the non-affected parents. The first de novo missense mutation at c.391T>C was identified in exon 3 of CRYGC on chromosome 2 causing the substitution of a highly conserved Tryptophan to an Arginine located at p.Trp131Arg. Previous studies exhibit significant changes in the tertiary structure of the crystallin family in the following variant locus, making CRYGC prone to aggregation aggravated by photodamage resulting in cataract. The variant can be classified as pathogenic according to the American College of Medical Genetics and Genomics (ACMG) criteria (PP3 + PM1 + PM2 + PS2; scoring 10 points). The identification of this novel variant expands the existing knowledge on the range of variants found in the CRYGC gene and contributes to a better comprehension of cataract heterogeneity.
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Affiliation(s)
- Flora Delas
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (F.D.); (S.K.); (S.F.)
| | - Samuel Koller
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (F.D.); (S.K.); (S.F.)
| | - Silke Feil
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (F.D.); (S.K.); (S.F.)
| | - Ivanka Dacheva
- Department of Ophthalmology, Cantonal Hospital of St. Gallen, 9007 St. Gallen, Switzerland;
| | | | - Wolfgang Berger
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Schlieren, Switzerland; (F.D.); (S.K.); (S.F.)
- Neuroscience Center Zürich (ZNZ), University of Zurich and ETH Zurich, 8006 Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8006 Zurich, Switzerland
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Springer MS, Emerling CA, Gatesy J. Three Blind Moles: Molecular Evolutionary Insights on the Tempo and Mode of Convergent Eye Degeneration in Notoryctes typhlops (Southern Marsupial Mole) and Two Chrysochlorids (Golden Moles). Genes (Basel) 2023; 14:2018. [PMID: 38002961 PMCID: PMC10671557 DOI: 10.3390/genes14112018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 10/20/2023] [Accepted: 10/25/2023] [Indexed: 11/26/2023] Open
Abstract
Golden moles (Chrysochloridae) and marsupial moles (Notoryctidae) are textbook examples of convergent evolution. Both taxa are highly adapted to subterranean lifestyles and have powerful limbs for digging through the soil/sand, ears that are adapted for low-frequency hearing, vestigial eyes that are covered by skin and fur, and the absence of optic nerve connections between the eyes and the brain. The eyes of marsupial moles also lack a lens as well as retinal rods and cones. Two hypotheses have been proposed to account for the greater degeneracy of the eyes of marsupial moles than golden moles. First, marsupial moles may have had more time to adapt to their underground habitat than other moles. Second, the eyes of marsupial moles may have been rapidly and recently vestigialized to (1) reduce the injurious effects of sand getting into the eyes and (2) accommodate the enlargement of lacrimal glands that keep the nasal cavity moist and prevent the entry of sand into the nasal passages during burrowing. Here, we employ molecular evolutionary methods on DNA sequences for 38 eye genes, most of which are eye-specific, to investigate the timing of relaxed selection (=neutral evolution) for different groups of eye-specific genes that serve as proxies for distinct functional components of the eye (rod phototransduction, cone phototransduction, lens/cornea). Our taxon sampling included 12 afrothere species, of which two are golden moles (Amblysomus hottentotus, Chrysochloris asiatica), and 28 marsupial species including two individuals of the southern marsupial mole (Notoryctes typhlops). Most of the sequences were mined from databases, but we also provide new genome data for A. hottentotus and one of the two N. typhlops individuals. Even though the eyes of golden moles are less degenerate than the eyes of marsupial moles, there are more inactivating mutations (e.g., frameshift indels, premature stop codons) in their cone phototransduction and lens/cornea genes than in orthologous genes of the marsupial mole. We estimate that cone phototransduction recovery genes were inactivated first in each group, followed by lens/cornea genes and then cone phototransduction activation genes. All three groups of genes were inactivated earlier in golden moles than in marsupial moles. For the latter, we estimate that lens/cornea genes were inactivated ~17.8 million years ago (MYA) when stem notoryctids were burrowing in the soft soils of Australian rainforests. Selection on phototransduction activation genes was relaxed much later (5.38 MYA), during the early stages of Australia's aridification that produced coastal sand plains and eventually sand dunes. Unlike cone phototransduction activation genes, rod phototransduction activation genes are intact in both golden moles and one of the two individuals of N. typhlops. A second marsupial mole individual has just a single inactivating mutation in one of the rod phototransduction activation genes (PDE6B). One explanation for this result is that some rod phototransduction activation genes are pleiotropic and are expressed in extraocular tissues, possibly in conjunction with sperm thermotaxis.
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Affiliation(s)
- Mark S. Springer
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA
| | | | - John Gatesy
- Division of Vertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA;
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Attia SA, Truong AT, Phan A, Lee SJ, Abanmai M, Markanovic M, Avila H, Luo H, Ali A, Sreekumar PG, Kannan R, MacKay JA. αB- Crystallin Peptide Fused with Elastin-like Polypeptide: Intracellular Activity in Retinal Pigment Epithelial Cells Challenged with Oxidative Stress. Antioxidants (Basel) 2023; 12:1817. [PMID: 37891896 PMCID: PMC10604459 DOI: 10.3390/antiox12101817] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 09/19/2023] [Accepted: 09/22/2023] [Indexed: 10/29/2023] Open
Abstract
BACKGROUND Oxidative stress-induced retinal degeneration is among the main contributing factors of serious ocular pathologies that can lead to irreversible blindness. αB-crystallin (cry) is an abundant component of the visual pathway in the vitreous humor, which modulates protein and cellular homeostasis. Within this protein exists a 20 amino acid fragment (mini-cry) with both chaperone and antiapoptotic activity. This study fuses this mini-cry peptide to two temperature-sensitive elastin-like polypeptides (ELP) with the goal of prolonging its activity in the retina. METHODS The biophysical properties and chaperone activity of cry-ELPs were confirmed by mass spectrometry, cloud-point determination, and dynamic light scattering 'DLS'. For the first time, this work compares a simpler ELP architecture, cry-V96, with a previously reported ELP diblock copolymer, cry-SI. Their relative mechanisms of cellular uptake and antiapoptotic potential were tested using retinal pigment epithelial cells (ARPE-19). Oxidative stress was induced with H2O2 and comparative internalization of both cry-ELPs was made using 2D and 3D culture models. We also explored the role of lysosomal membrane permeabilization by confocal microscopy. RESULTS The results indicated successful ELP fusion, cellular association with both 2D and 3D cultures, which were enhanced by oxidative stress. Both constructs suppressed apoptotic signaling (cleaved caspase-3); however, cry-V96 exhibited greater lysosomal escape. CONCLUSIONS ELP architecture is a critical factor to optimize delivery of therapeutic peptides, such as the anti-apoptotic mini-cry peptide; furthermore, the protection of mini-cry via ELPs is enhanced by lysosomal membrane permeabilization.
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Affiliation(s)
- Sara Aly Attia
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
| | - Anh Tan Truong
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
| | - Alvin Phan
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
| | - Shin-Jae Lee
- Mann Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA;
| | - Manal Abanmai
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
- Department of Pharmaceutics, College of Pharmacy, Prince Sattam bin Abdulaziz University, Al Kharj 11942, Saudi Arabia
| | - Marinella Markanovic
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
| | - Hugo Avila
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
| | - Haozhong Luo
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
| | - Atham Ali
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
| | | | - Ram Kannan
- Doheny Eye Institute, Pasadena, CA 91103, USA; (P.G.S.); (R.K.)
- Stein Eye Institute, Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - J. Andrew MacKay
- Department of Pharmacology and Pharmaceutical Sciences, Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (S.A.A.); (A.T.T.); (A.P.); (M.A.); (M.M.); (H.A.); (H.L.); (A.A.)
- Mann Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA;
- Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
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Rolland AD, Takata T, Donor MT, Lampi KJ, Prell JS. Eye lens β- crystallins are predicted by native ion mobility-mass spectrometry and computations to form compact higher-ordered heterooligomers. Structure 2023; 31:1052-1064.e3. [PMID: 37453416 PMCID: PMC10528727 DOI: 10.1016/j.str.2023.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 05/04/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023]
Abstract
Eye lens α- and β-/γ-crystallin proteins are not replaced after fiber cell denucleation and maintain lens transparency and refractive properties. The exceptionally high (∼400-500 mg/mL) concentration of crystallins in mature lens tissue and multiple other factors impede precise characterization of β-crystallin interactions, oligomer composition, size, and topology. Native ion mobility-mass spectrometry is used here to probe β-crystallin association and provide insight into homo- and heterooligomerization kinetics for these proteins. These experiments include separation and characterization of higher-order β-crystallin oligomers and illustrate the unique advantages of native IM-MS. Recombinantly expressed βB1, βB2, and βA3 isoforms are found to have different homodimerization propensities, and only βA3 forms larger homooligomers. Heterodimerization of βB2 with βA3 occurs ∼3 times as fast as that of βB1 with βA3, and βB1 and βB2 heterodimerize less readily. Ion mobility experiments, molecular dynamics simulations, and PISA analysis together reveal that observed oligomers are consistent with predominantly compact, ring-like topologies.
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Affiliation(s)
- Amber D Rolland
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403-1253, USA
| | - Takumi Takata
- Kyoto University, Research Reactor Institute 2, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Micah T Donor
- Department of Biological & Molecular Sciences, George Fox University, 414 N Meridian St, Newberg, OR 97132, USA
| | - Kirsten J Lampi
- Integrative Biosciences, School of Dentistry, 3181 SW Sam Jackson Park Road, Oregon Health & Science University, Portland, OR 97239-3098, USA.
| | - James S Prell
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403-1253, USA; Materials Science Institute, 1252 University of Oregon, Eugene, OR 97403-1252, USA.
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6
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Minogue PJ, Gao J, Mathias RT, Williams JC, Bledsoe SB, Sommer AJ, Beyer EC, Berthoud VM. A crystallin mutant cataract with mineral deposits. J Biol Chem 2023; 299:104935. [PMID: 37331601 PMCID: PMC10407958 DOI: 10.1016/j.jbc.2023.104935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 06/20/2023] Open
Abstract
Connexin mutant mice develop cataracts containing calcium precipitates. To test whether pathologic mineralization is a general mechanism contributing to the disease, we characterized the lenses from a nonconnexin mutant mouse cataract model. By cosegregation of the phenotype with a satellite marker and genomic sequencing, we identified the mutant as a 5-bp duplication in the γC-crystallin gene (Crygcdup). Homozygous mice developed severe cataracts early, and heterozygous animals developed small cataracts later in life. Immunoblotting studies showed that the mutant lenses contained decreased levels of crystallins, connexin46, and connexin50 but increased levels of resident proteins of the nucleus, endoplasmic reticulum, and mitochondria. The reductions in fiber cell connexins were associated with a scarcity of gap junction punctae as detected by immunofluorescence and significant reductions in gap junction-mediated coupling between fiber cells in Crygcdup lenses. Particles that stained with the calcium deposit dye, Alizarin red, were abundant in the insoluble fraction from homozygous lenses but nearly absent in wild-type and heterozygous lens preparations. Whole-mount homozygous lenses were stained with Alizarin red in the cataract region. Mineralized material with a regional distribution similar to the cataract was detected in homozygous lenses (but not wild-type lenses) by micro-computed tomography. Attenuated total internal reflection Fourier-transform infrared microspectroscopy identified the mineral as apatite. These results are consistent with previous findings that loss of lens fiber cell gap junctional coupling leads to the formation of calcium precipitates. They also support the hypothesis that pathologic mineralization contributes to the formation of cataracts of different etiologies.
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Affiliation(s)
- Peter J Minogue
- Department of Pediatrics, University of Chicago, Chicago, Illinois, USA
| | - Junyuan Gao
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA
| | - Richard T Mathias
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA
| | - James C Williams
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sharon B Bledsoe
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Andre J Sommer
- Molecular Microspectroscopy Laboratory, Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, USA
| | - Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, Illinois, USA
| | - Viviana M Berthoud
- Department of Pediatrics, University of Chicago, Chicago, Illinois, USA.
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Jing X, Zhu M, Lu X, Wei P, Shi L, Zhang BY, Xu Y, Tang YP, Xiang DM, Gong P. Cataract-causing Y204X mutation of crystallin protein CRYβB1 promotes its C-terminal degradation and higher-order oligomerization. J Biol Chem 2023; 299:104953. [PMID: 37356717 PMCID: PMC10382669 DOI: 10.1016/j.jbc.2023.104953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/16/2023] [Accepted: 06/19/2023] [Indexed: 06/27/2023] Open
Abstract
Crystallin proteins are a class of main structural proteins of the vertebrate eye lens, and their solubility and stability directly determine transparency and refractive power of the lens. Mutation in genes that encode these crystallin proteins is the most common cause for congenital cataracts. Despite extensive studies, the pathogenic and molecular mechanisms that effect congenital cataracts remain unclear. In this study, we identified a novel mutation in CRYBB1 from a congenital cataract family, and demonstrated that this mutation led to an early termination of mRNA translation, resulting in a 49-residue C-terminally truncated CRYβB1 protein. We show this mutant is susceptible to proteolysis, which allowed us to determine a 1.2-Å resolution crystal structure of CRYβB1 without the entire C-terminal domain. In this crystal lattice, we observed that two N-terminal domain monomers form a dimer that structurally resembles the WT monomer, but with different surface characteristics. Biochemical analyses and cell-based data also suggested that this mutant is significantly more liable to aggregate and degrade compared to WT CRYβB1. Taken together, our results provide an insight into the mechanism regarding how a mutant crystalin contributes to the development of congenital cataract possibly through alteration of inter-protein interactions that result in protein aggregation.
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Affiliation(s)
- Xuping Jing
- Joint Laboratory for Translational Precision Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China; Joint Laboratory for Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China; Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Mingwei Zhu
- Joint Laboratory for Translational Precision Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China; Joint Laboratory for Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Xiaoyun Lu
- Joint Laboratory for Translational Precision Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China; Joint Laboratory for Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Ping Wei
- Joint Laboratory for Translational Precision Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China; Joint Laboratory for Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Lingyu Shi
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Bu-Yu Zhang
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yi Xu
- Joint Laboratory for Translational Precision Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China; Joint Laboratory for Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Ya-Ping Tang
- Joint Laboratory for Translational Precision Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China; Joint Laboratory for Translational Precision Medicine, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China; Goungdong Key Laboratory of Structural Birth Defects, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China; Department of Imaging, Affiliated Hospital 3, Zhengzhou University, Zhengzhou, Henan, China.
| | - Dao-Man Xiang
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China.
| | - Peng Gong
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China.
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Weininger S, Neudorf M, Gröger S, Plato E, Broneske R, Saalwächter K, Weininger U, Balbach J. Early Stage UV-B Induced Molecular Modifications of Human Eye Lens γD- Crystallin. Macromol Biosci 2023; 23:e2200526. [PMID: 36808690 DOI: 10.1002/mabi.202200526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/01/2023] [Indexed: 02/23/2023]
Abstract
In the human eye lenses, the crystallin proteins facilitate transparency, light refraction, as well as UV light protection. A deregulated balanced interplay between α-, β-, and γ-crystallin can cause cataract. γD-crystallin (hγD) is involved in the energy dissipation of absorbed UV light by energy transfer between aromatic side chains. Early UV-B induced damage of hγD with molecular resolution is studied by solution NMR and fluorescence spectroscopy. hγD modifications are restricted to Tyr 17 and Tyr 29 in the N-terminal domain, where a local unfolding of the hydrophobic core is observed. None of the tryptophan residues assisting fluorescence energy transfer is modified and hγD is remained soluble over month. Investigating isotope-labeled hγD surrounded by eye lens extracts from cataract patients reveals very week interactions of solvent-exposed side chains in the C-terminal hγD domain and some remaining photoprotective properties of the extracts. Hereditary E107A hγD found in the eye lens core of infants developing cataract shows under the here used conditions a thermodynamic stability comparable to the wild type but an increased sensitivity toward UV-B irradiation.
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Affiliation(s)
- Susanne Weininger
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
| | - Malte Neudorf
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
| | - Stefan Gröger
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
| | - Eric Plato
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
| | - Robert Broneske
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
| | - Kay Saalwächter
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
| | - Ulrich Weininger
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
| | - Jochen Balbach
- Martin Luther University Halle-Wittenberg, Institute of Physics, Betty-Heimann-Strasse 7, DE-06120, Halle, Germany
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9
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Peng Y, Zheng Y, Deng Z, Zhang S, Tan Y, Hu Z, Tao L, Luo Y. Case Report: A de novo Variant of CRYGC Gene Associated With Congenital Cataract and Microphthalmia. Front Genet 2022; 13:866246. [PMID: 35719371 PMCID: PMC9198712 DOI: 10.3389/fgene.2022.866246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/11/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Congenital cataract is one of the most common causes of blindness in children. A rapid and accurate genetic diagnosis benefit the patients in the pediatric department. The current study aims to identify the genetic defects in a congenital cataract patient without a family history. Case presentation: A congenital cataract patient with microphthalmia and nystagmus was recruited for this study. Trio-based whole-exome sequencing revealed a de novo variant (c.394delG, p.V132Sfs*15) in CRYGC gene. According to the American College of Medical Genetics and Genomics (ACMG) criteria, the variant could be annontated as pathogenic. Conclusion: Our findings provide new knowledge of the variant spectrum of CRYGC gene and are essential for understanding the heterogeneity of cataracts in the Chinese population.
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Affiliation(s)
- Yu Peng
- Department of Ophthalmology & Pediatrics Research Institute of Hunan Province, Hunan Children's Hospital, Changsha, China
| | - Yu Zheng
- Pediatrics Research Institute of Hunan Province, Hunan Children's Hospital, Changsha, China
| | - Zifeng Deng
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
| | - Shuju Zhang
- Pediatrics Research Institute of Hunan Province, Hunan Children's Hospital, Changsha, China
| | - Yilan Tan
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
| | - Zhengmao Hu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Lijuan Tao
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
| | - Yulin Luo
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
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10
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Norton-Baker B, Mehrabi P, Kwok AO, Roskamp KW, Rocha MA, Sprague-Piercy MA, von Stetten D, Miller RJD, Martin RW. Deamidation of the human eye lens protein γS- crystallin accelerates oxidative aging. Structure 2022:S0969-2126(22)00083-1. [PMID: 35338852 DOI: 10.1016/j.str.2022.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 12/14/2021] [Accepted: 03/01/2022] [Indexed: 11/23/2022]
Abstract
Cataract, a clouding of the eye lens from protein precipitation, affects millions of people every year. The lens proteins, the crystallins, show extensive post-translational modifications (PTMs) in cataractous lenses. The most common PTMs, deamidation and oxidation, promote crystallin aggregation; however, it is not clear precisely how these PTMs contribute to crystallin insolubilization. Here, we report six crystal structures of the lens protein γS-crystallin (γS): one of the wild-type and five of deamidated γS variants, from three to nine deamidation sites, after sample aging. The deamidation mutations do not change the overall fold of γS; however, increasing deamidation leads to accelerated disulfide-bond formation. Addition of deamidated sites progressively destabilized protein structure, and the deamidated variants display an increased propensity for aggregation. These results suggest that the deamidated variants are useful as models for accelerated aging; the structural changes observed provide support for redox activity of γS-crystallin in the lens.
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11
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Carmy-Bennun T, Myer C, Bhattacharya SK, Hackam AS. Quantitative proteomic analysis after neuroprotective MyD88 inhibition in the retinal degeneration 10 mouse. J Cell Mol Med 2021; 25:9533-9542. [PMID: 34562309 PMCID: PMC8505828 DOI: 10.1111/jcmm.16893] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 08/13/2021] [Accepted: 08/18/2021] [Indexed: 12/18/2022] Open
Abstract
Progressive photoreceptor death occurs in blinding diseases such as retinitis pigmentosa. Myeloid differentiation primary response protein 88 (MyD88) is a central adaptor protein for innate immune system Toll-like receptors (TLR) and induces cytokine secretion during retinal disease. We recently demonstrated that inhibiting MyD88 in mouse models of retinal degeneration led to increased photoreceptor survival, which was associated with altered cytokines and increased neuroprotective microglia. However, the identity of additional molecular changes associated with MyD88 inhibitor-induced neuroprotection is not known. In this study, we used isobaric tags for relative and absolute quantification (iTRAQ) labelling followed by LC-MS/MS for quantitative proteomic analysis on the rd10 mouse model of retinal degeneration to identify protein pathways changed by MyD88 inhibition. Quantitative proteomics using iTRAQ LC-MS/MS is a high-throughput method ideal for providing insight into molecular pathways during disease and experimental treatments. Forty-two proteins were differentially expressed in retinas from mice treated with MyD88 inhibitor compared with control. Notably, increased expression of multiple crystallins and chaperones that respond to cellular stress and have anti-apoptotic properties was identified in the MyD88-inhibited mice. These data suggest that inhibiting MyD88 enhances chaperone-mediated retinal protection pathways. Therefore, this study provides insight into molecular events contributing to photoreceptor protection from modulating inflammation.
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Affiliation(s)
- Tal Carmy-Bennun
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Ciara Myer
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Miami Integrative Metabolomics Research Center, Miami, FL, USA
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Miami Integrative Metabolomics Research Center, Miami, FL, USA
| | - Abigail S Hackam
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Miami Integrative Metabolomics Research Center, Miami, FL, USA
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12
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Deravi LF. Compositional similarities that link the eyes and skin of cephalopods: Implications in optical sensing and signaling during camouflage. Integr Comp Biol 2021; 61:1511-1516. [PMID: 34160621 DOI: 10.1093/icb/icab143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cephalopods, including squid, octopus, and cuttlefish, can rapidly camouflage in different underwater environments by employing multiple optical effects including light scattering, absorption, reflection, and refraction. They can do so with exquisite control and within a fraction of a second-two features that indicate distributed, intra-dermal sensory and signaling components. However, the fundamental biochemical, electrical, and mechanical controls that regulate color and color change, from discrete elements to interconnected modules, are still not fully understood despite decades of research in this space. This perspective highlights key advancements in the biochemical analysis of cephalopod skin and discusses compositional connections between cephalopod ocular lenses and skin with features that may also facilitate signal transduction during camouflage.
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Affiliation(s)
- Leila F Deravi
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, 102 Hurtig Hall, 360 Huntington Ave, Boston, MA 02115
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13
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Zhu XJ, Zhang KK, He WW, Qi J, Lu Y. Racemization in cataractous lens from diabetic and aging individuals: analysis of Asp 58 residue in αA- crystallin. Aging (Albany NY) 2021; 13:15255-68. [PMID: 34096886 DOI: 10.18632/aging.203086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 04/29/2021] [Indexed: 11/25/2022]
Abstract
Cataract is the leading cause of visual impairment globally. Racemization of lens proteins may contribute to cataract formation in aging individuals. As a special type of age-related cataract (ARC), diabetic cataract (DC) is characterized by the early onset of cortical opacification and finally developed into a mixed type of cortical and nuclear opacification. We compared racemization of Asp 58 residue, a hotspot position in αA-crystallin, from the cortex and nucleus of diabetic and age-matched senile cataractous lenses, by identifying L-Asp/L-isoAsp/D-Asp/D-isoAsp by mass spectrometry. Compared to nondiabetic cataractous lenses, DC lenses showed a significantly increased cortex/nucleus ratio of D-Asp 58, which originated primarily from an increased percentage of D-Asp 58 in the lens cortex of DC. Moreover, patients diagnosed with diabetes for over 10 years showed a lower cortex/nucleus ratio of D-isoAsp 58 in the lens compared with those who had a shorter duration of diabetes, which originated mainly from an increased percentage of D-isoAsp 58 in the lens nucleus of DC with increasing time of hyperglycemia. Further analysis confirmed decreased protein solubility in diabetic cataractous lenses. The different racemization pattern in DC may be distinguished from ARC and influence its phenotype over the protracted duration of diabetes.
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14
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Abstract
Congenital cataract is a challenging ophthalmological disorder which can cause severe visual loss. It can be diagnosed at birth or during the first year of life. Early diagnosis and treatment are crucial for the visual prognosis. It can be associated with various ocular and systemic abnormalities. Determining whether congenital cataract is isolated or associated with other pathology is an indispensable step for the prediction of potential vision as well as early diagnosis and treatment of conditions that can cause morbidity or mortality. Many genes have been identified in the molecular etiology of congenital cataract. Most mutations have been reported in the crystallin genes. Determination of the genetic cause may not only enable individualized genetic counseling but also help to identify concomitant ocular and/or systemic disorders depending on the characteristics of the genetic test used. Recently, next-generation sequencing in particular has become an evolving technology for determining the molecular etiology of congenital cataract and furthering our knowledge of the disease.
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Affiliation(s)
| | - Gülen Eda Utine
- Hacettepe University Faculty of Medicine, Department of Pediatrics, Department of Pediatric Genetics, Ankara, Turkey
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15
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Kandaswamy DK, Vasantha K, Graw J, Santhiya ST. A novel CRYGC E128* mutation underlying an autosomal dominant nuclear cataract in a south Indian kindred. Ophthalmic Genet 2020; 41:556-562. [PMID: 32811259 DOI: 10.1080/13816810.2020.1807027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE To identify the mutation causing an autosomal dominant congenital nuclear cataract in a south Indian family by whole exome sequencing and to characterize further phenotypically the same in a zebra fish model. METHODS A six-generation family (DKEC1) with several affected members registered at the Regional Institute of Ophthalmology (RIO), Chennai was documented to have congenital nuclear cataract. Detailed clinical history and blood samples were collected from all available family members. Genomic DNA of the proband was subjected to whole exome sequencing. Sequence variations suggestive of putative mutations were further confirmed by bidirectional sequencing and restriction site analysis. Functional analysis of the mutant CRYGC E128* in zebrafish embryos was done to dissect out the pathogenicity. RESULTS A unique variation viz., c.382 G > T in the coding region of the CRYGC gene, resulting in a premature stop codon at position 128 (E128*) was documented in the affected family members. The same was absent in unaffected family members and in 120 unrelated population controls checked. Bioinformatic tools predicted that the mutation might cause a deleterious effect on protein structure and function. Molecular function analysis of this novel mutation (p. E128*, CRYGC) in the zebrafish indicated this mutation to impair lens transparency. CONCLUSION This study identified a novel CRYGC mutation, E128* to cause autosomal dominant congenital nuclear cataract in a large south Indian family. Our study provides a new insight onto how the mutation might affect the γC-crystallin structure and function besides emphasizing the need for genetic diagnosis toward vision restoration.
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Affiliation(s)
- Dinesh Kumar Kandaswamy
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras , Chennai, India.,Institute of Developmental Genetics, Helmholtz Zentrum München , Neuherberg, Germany.,School of Optometry and Vision Sciences, Cardiff University , Cardiff, UK
| | - K Vasantha
- Regional Institute of Ophthalmology (RIO), Government Eye Hospital , Chennai, India
| | - Jochen Graw
- Institute of Developmental Genetics, Helmholtz Zentrum München , Neuherberg, Germany
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16
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Nandi SK, Nahomi RB, Rankenberg J, Glomb MA, Nagaraj RH. Glycation-mediated inter-protein cross-linking is promoted by chaperone-client complexes of α- crystallin: Implications for lens aging and presbyopia. J Biol Chem 2020; 295:5701-5716. [PMID: 32184356 PMCID: PMC7186181 DOI: 10.1074/jbc.ra120.012604] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/12/2020] [Indexed: 12/16/2022] Open
Abstract
Lens proteins become increasingly cross-linked through nondisulfide linkages during aging and cataract formation. One mechanism that has been implicated in this cross-linking is glycation through formation of advanced glycation end products (AGEs). Here, we found an age-associated increase in stiffness in human lenses that was directly correlated with levels of protein-cross-linking AGEs. α-Crystallin in the lens binds to other proteins and prevents their denaturation and aggregation through its chaperone-like activity. Using a FRET-based assay, we examined the stability of the αA-crystallin-γD-crystallin complex for up to 12 days and observed that this complex is stable in PBS and upon incubation with human lens-epithelial cell lysate or lens homogenate. Addition of 2 mm ATP to the lysate or homogenate did not decrease the stability of the complex. We also generated complexes of human αA-crystallin or αB-crystallin with alcohol dehydrogenase or citrate synthase by applying thermal stress. Upon glycation under physiological conditions, the chaperone-client complexes underwent greater extents of cross-linking than did uncomplexed protein mixtures. LC-MS/MS analyses revealed that the levels of cross-linking AGEs were significantly higher in the glycated chaperone-client complexes than in glycated but uncomplexed protein mixtures. Mouse lenses subjected to thermal stress followed by glycation lost resilience more extensively than lenses subjected to thermal stress or glycation alone, and this loss was accompanied by higher protein cross-linking and higher cross-linking AGE levels. These results uncover a protein cross-linking mechanism in the lens and suggest that AGE-mediated cross-linking of α-crystallin-client complexes could contribute to lens aging and presbyopia.
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Affiliation(s)
- Sandip K Nandi
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Rooban B Nahomi
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Johanna Rankenberg
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Marcus A Glomb
- Institute of Chemistry-Food Chemistry, Martin-Luther-University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Ram H Nagaraj
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045; Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045.
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17
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Takata T, Ha S, Koide T, Fujii N. Site-specific rapid deamidation and isomerization in human lens αA- crystallin in vitro. Protein Sci 2020; 29:955-965. [PMID: 31930615 PMCID: PMC7096717 DOI: 10.1002/pro.3821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/27/2019] [Accepted: 12/27/2019] [Indexed: 12/16/2022]
Abstract
Recent studies have suggested that the isomerization/racemization of aspartate residues in proteins increases in aged tissues. One such residue is Asp151 in lens-specific αA-crystallin. Although many isomerization/racemization sites have been reported in various proteins, the factors that lead to those modifications in proteins in vivo remain obscure. Therefore, an in vitro system is needed to assess the mechanisms of modifications of Asp under various conditions. Deamidation of Asn to Asp in proteins occurs more rapidly than isomerization/racemization of Asp, although the reaction passes through the same intermediate in both pathways. Here, therefore, we replaced Asp151 in human lens αA-crystallin with Asn by using site-directed mutagenesis. The recombinant protein was expressed in Escherichia coli and used to investigate the deamidation/isomerization/racemization of Asn151 after incubation at 50°C for various durations and under different pH. After incubation, the mutant αA-crystallin was subjected to enzymatic digestion followed by liquid chromatography-MS/MS to evaluate the ratio of modifications in Asn151-containing peptides. The Asp151Asn αA-crystallin mutant showed rapid deamidation to Asp with the formation of specific Asp isomers. In particular, deamidation increased greatly under basic conditions. By contrast, subunit-subunit interactions between αA-crystallin and αB-crystallin had little effect on the modification of Asn151. Our findings suggest that the Asp151Asn αA-crystallin mutant represents a good in vitro model protein to assess deamidation, isomerization, and the racemization intermediates. Furthermore, our in vitro results show a different trend from in vivo data, implying the presence of specific factors that induce racemization from L-Asp to D-Asp residues in vivo.
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Affiliation(s)
- Takumi Takata
- Kyoto University Institute for Integrated Radiation and Nuclear ScienceOsakaJapan
| | - Seongmin Ha
- Department of ChemistryGraduate School of Science, Kyoto UniversityKyotoJapan
| | | | - Noriko Fujii
- Kyoto University Institute for Integrated Radiation and Nuclear ScienceOsakaJapan
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18
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Prokai L, Zaman K, Nguyen V, Prokai-Tatrai K. 17β-Estradiol Delivered in Eye Drops: Evidence of Impact on Protein Networks and Associated Biological Processes in the Rat Retina through Quantitative Proteomics. Pharmaceutics 2020; 12:E101. [PMID: 32012756 DOI: 10.3390/pharmaceutics12020101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/22/2020] [Accepted: 01/22/2020] [Indexed: 11/17/2022] Open
Abstract
To facilitate the development of broad-spectrum retina neuroprotectants that can be delivered through topical dosage forms, this proteomics study focused on analyzing target engagements through the identification of functional protein networks impacted after delivery of 17β-estradiol in eye drops. Specifically, the retinae of ovariectomized Brown Norway rats treated with daily eye drops of 17β-estradiol for three weeks were compared to those of vehicle-treated ovariectomized control animals. We searched the acquired raw data against a composite protein sequence database by using Mascot, as well as employed label-free quantification to detect changes in protein abundances. Our investigation using rigorous validation criteria revealed 331 estrogen-regulated proteins in the rat retina (158 were up-regulated, while 173 were down-regulated by 17β-estradiol delivered in eye drops). Comprehensive pathway analyses indicate that these proteins are relevant overall to nervous system development and function, tissue development, organ development, as well as visual system development and function. We also present 18 protein networks with associated canonical pathways showing the effects of treatments for the detailed analyses of target engagements regarding potential application of estrogens as topically delivered broad-spectrum retina neuroprotectants. Profound impact on crystallins is discussed as one of the plausible neuroprotective mechanisms.
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19
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Rathinam S, Daniel I, Kuppamuthu D, Jayapal JM. Molecular Mimicry between Betaine Aldehyde Dehydrogenase of Leptospira and Retinal Dehydrogenase 1 of Human Lens: A Potential Trigger for Cataract Formation in Leptospiral Uveitis Patients. Ocul Immunol Inflamm 2019; 29:579-586. [PMID: 31746662 DOI: 10.1080/09273948.2019.1687732] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Purpose: Rapidly progressing cataract is one of the ocular manifestations in leptospiral uveitis patients. We examined whether molecular mimicry between the leptospira antigens and lens proteins exists that could result in cataract in these patients.Methods: Immunoblot analysis using patient sera was done with proteins from normal lens and cataract lens from leptospiral uveitis patients and the cross-reacting lens proteins were identified by mass spectrometry analysis.Results: Retinal dehydrogenase 1 and crystallins (α-B, α-A2, β-B2), were recognized by the antibodies in the serum of leptospiral uveitis patients. And, retinal dehydrogenase 1 is homologous to the leptospiral protein, betaine aldehyde dehydrogenase.Conclusions: Leptospiral uveitis patient serum contains antibodies that cross-react with multiple lens proteins that have a role in maintaining lens transparency. And, these antibodies could act as a potential trigger for cataractogenesis.
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Affiliation(s)
| | - Irene Daniel
- Proteomics Department, Aravind Medical Research Foundation, Madurai, India
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20
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Forsythe HM, Vetter CJ, Jara KA, Reardon PN, David LL, Barbar EJ, Lampi KJ. Altered Protein Dynamics and Increased Aggregation of Human γS- Crystallin Due to Cataract-Associated Deamidations. Biochemistry 2019; 58:4112-4124. [PMID: 31490062 PMCID: PMC10693687 DOI: 10.1021/acs.biochem.9b00593] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Deamidation is a major age-related modification in the human lens that is highly prevalent in crystallins isolated from the insoluble fraction of cataractous lenses and also causes protein aggregation in vitro. However, the mechanism by which deamidation causes proteins to become insoluble is not known because only subtle structural changes were observed in vitro. We have identified Asn14 and Asn76 of γS-crystallin as highly deamidated in insoluble proteins isolated from aged lenses. These sites are on the surface of the N-terminal domain and were mimicked by replacing the Asn with Asp residues in order to generate recombinant human γS and deamidated mutants. Both N14D and N76D had increased light scattering compared to wild-type γS (WT) and increased aggregation during thermal-induced denaturation. Aggregation was enhanced by oxidized glutathione, suggesting deamidation may increase susceptibility to form disulfide bonds. These changes were correlated to changes in protein dynamics determined by NMR spectroscopy. Heteronuclear NMR spectroscopy was used to measure amide hydrogen exchange and 15N relaxation dynamics to identify regions with increased dynamics compared to γS WT. Residue-specific changes in solvent accessibility and dynamics were both near and distant from the sites of deamidation, suggesting that deamidation had both local and global effects on the protein structure at slow (ms to s) and fast (μs to ps) time scales. Thus, a potential mechanism for γS deamidation-induced insolubilization in cataractous lenses is altered dynamics due to local regions of unfolding and increased flexibility in both the N- and C-terminal domains particularly at surface helices. This conformational flexibility increases the likelihood of aggregation, which would be enhanced in the oxidizing cytoplasm of the aged and cataractous lens. The NMR data combined with the in vivo insolubility and in vitro aggregation findings support a model that deamidation drives changes in protein dynamics that facilitate protein aggregation associated with cataracts.
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Affiliation(s)
| | - Calvin J. Vetter
- Integrative Biosciences, Oregon Health & Science University, Portland, OR
| | - Kayla Ann Jara
- Biochemistry & Biophysics, Oregon State University, Corvallis, OR
| | - Patrick N. Reardon
- Nuclear Magnetic Resonance Facility, Oregon State University, Corvallis, OR
| | - Larry L. David
- Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, OR
| | - Elisar J. Barbar
- Biochemistry & Biophysics, Oregon State University, Corvallis, OR
| | - Kirsten J. Lampi
- Integrative Biosciences, Oregon Health & Science University, Portland, OR
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21
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Abstract
Cataract, the clinical correlate of opacity or light scattering in the eye lens, is usually caused by the presence of high-molecular-weight (HMW) protein aggregates or disruption of the lens microarchitecture. In general, genes involved in inherited cataracts reflect important processes and pathways in the lens including lens crystallins, connexins, growth factors, membrane proteins, intermediate filament proteins, and chaperones. Usually, mutations causing severe damage to proteins cause congenital cataracts, while milder variants increasing susceptibility to environmental insults are associated with age-related cataracts. These may have different pathogenic mechanisms: Congenital cataracts induce the unfolded protein response and apoptosis. By contrast, denatured crystallins in age-related cataracts are bound by α-crystallin and form light-scattering HMW aggregates. New therapeutic approaches to age-related cataracts use chemical chaperones to solubilize HMW aggregates, while attempts are being made to regenerate lenses using endogenous stem cells to treat congenital cataracts.
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Affiliation(s)
- Alan Shiels
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-1860, USA;
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22
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Bhat SP, Gangalum RK, Kim D, Mangul S, Kashyap RK, Zhou X, Elashoff D. Transcriptional profiling of single fiber cells in a transgenic paradigm of an inherited childhood cataract reveals absence of molecular heterogeneity. J Biol Chem 2019; 294:13530-13544. [PMID: 31243103 PMCID: PMC6746439 DOI: 10.1074/jbc.ra119.008853] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/21/2019] [Indexed: 11/06/2022] Open
Abstract
Our recent single-cell transcriptomic analysis has demonstrated that heterogeneous transcriptional activity attends molecular transition from the nascent to terminally differentiated fiber cells in the developing mouse lens. To understand the role of transcriptional heterogeneity in terminal differentiation and the functional phenotype (transparency) of this tissue, here we present a single-cell analysis of the developing lens, in a transgenic paradigm of an inherited pathology, known as the lamellar cataract. Cataracts hinder transmission of light into the eye. Lamellar cataract is the most prevalent bilateral childhood cataract. In this disease of early infancy, initially, the opacities remain confined to a few fiber cells, thus presenting an opportunity to investigate early molecular events that lead to cataractogenesis. We used a previously established paradigm that faithfully recapitulates this disease in transgenic mice. About 500 single fiber cells, manually isolated from a 2-day-old transgenic lens were interrogated individually for the expression of all known 17 crystallins and 78 other relevant genes using a Biomark HD (Fluidigm). We find that fiber cells from spatially and developmentally discrete regions of the transgenic (cataract) lens show remarkable absence of the heterogeneity of gene expression. Importantly, the molecular variability of cortical fiber cells, the hallmark of the WT lens, is absent in the transgenic cataract, suggesting absence of specific cell-type(s). Interestingly, we find a repetitive pattern of gene activity in progressive states of differentiation in the transgenic lens. This molecular dysfunction portends pathology much before the physical manifestations of the disease.
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Affiliation(s)
- Suraj P Bhat
- Stein Eye Institute, Geffen School of Medicine, University of California, Los Angeles, California 90095-7000
- Brain Research Institute, University of California, Los Angeles, California 90095-7000
- Molecular Biology Institute, University of California, Los Angeles, California 90095-7000
| | - Rajendra K Gangalum
- Stein Eye Institute, Geffen School of Medicine, University of California, Los Angeles, California 90095-7000
| | - Dongjae Kim
- Stein Eye Institute, Geffen School of Medicine, University of California, Los Angeles, California 90095-7000
| | - Serghei Mangul
- Department of Computer Science and Human Genetics, University of California, Los Angeles, California 90095-7000
| | - Raj K Kashyap
- Stein Eye Institute, Geffen School of Medicine, University of California, Los Angeles, California 90095-7000
| | - Xinkai Zhou
- Department of Medicine, University of California, Los Angeles, California 90095-7000
| | - David Elashoff
- Department of Medicine, University of California, Los Angeles, California 90095-7000
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23
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Hua H, Yang T, Huang L, Chen R, Li M, Zou Z, Wang N, Yang D, Liu Y. Protective Effects of Lanosterol Synthase Up-Regulation in UV-B-Induced Oxidative Stress. Front Pharmacol 2019; 10:947. [PMID: 31555133 PMCID: PMC6726740 DOI: 10.3389/fphar.2019.00947] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/24/2019] [Indexed: 12/17/2022] Open
Abstract
UV-B radiation may be an important risk factor in cataract etiology. After exposure to UV-B radiation, cells show imbalances in the repair of DNA damage, which induce changes in the levels of certain proteins, including alpha-crystallin, which is the most abundant protein in the lens and crucial for the maintenance of lens transparency. Lanosterol synthase (LSS), an essential rate-limiting enzyme in cholesterol biosynthesis, might play significant roles in oxidative stress and in the maintenance of lens transparency. However, the roles of LSS in UV-B-induced apoptosis are not well understood. Therefore, we irradiated female Sprague-Dawley rats with ultraviolet radiation to establish an animal model for exploring the variations in LSS expression during the early stages of UV-B exposure. In addition, we cultured human lens epithelial (HLE) cells that overexpress LSS and exposed them to UV-B radiation to explore the function of increased LSS expression in UV-B-induced apoptosis. The data demonstrated that UV-B exposure induced oxidative stress and apoptosis in rat lens epithelial cells and that irradiance exposure increased the level of lenticular damage. Additionally, UV-B exposure decreased the alpha-crystallin content and increased the expressions of Bax and cleaved caspase-3 compared with the control levels. After exposure to UV-B, the apoptosis-related index of HLE cells overexpressing LSS was lower than that of the control cells. Furthermore, ROS overproduction might activate the sirtuin 1 (Sirt1) pathway, which induced protein expressions of sterol regulatory element-binding transcription factor 2 (SREBF2), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), and LSS. However, the specific mechanism of the Sirt1 pathway needed to be further studied. In summary, UV-B exposure induced oxidative injury and resulted in crystallin denaturation and apoptosis in lens epithelial cells, and LSS might play a protective role during the early stages of this process and could be an important target in the cataract prevention.
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Affiliation(s)
- Hui Hua
- School of Public Health, China Medical University, Shenyang, China
| | - Tianyao Yang
- School of Public Health, China Medical University, Shenyang, China
| | - Liting Huang
- School of Public Health, China Medical University, Shenyang, China
| | - Rentong Chen
- School of Public Health, China Medical University, Shenyang, China
| | - Menglin Li
- School of Public Health, China Medical University, Shenyang, China
| | - Zhenzhen Zou
- School of Public Health, China Medical University, Shenyang, China
| | - Nan Wang
- School of Public Health, China Medical University, Shenyang, China
| | - Dan Yang
- School of Public Health, China Medical University, Shenyang, China
| | - Yang Liu
- School of Public Health, China Medical University, Shenyang, China
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24
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A L, Zou T, He J, Chen X, Sun D, Fan X, Xu H. Rescue of Retinal Degeneration in rd1 Mice by Intravitreally Injected Metformin. Front Mol Neurosci 2019; 12:102. [PMID: 31080404 PMCID: PMC6497809 DOI: 10.3389/fnmol.2019.00102] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 04/04/2019] [Indexed: 12/18/2022] Open
Abstract
Retinitis pigmentosa (RP) is a progressive hereditary retinal degenerative disease in which photoreceptor cells undergo degeneration and apoptosis, eventually resulting in irreversible loss of visual function. Currently, no effective treatment exists for this disease. Neuroprotection and inflammation suppression have been reported to delay the development of RP. Metformin is a well-tested drug used to treat type 2 diabetes, and it has been reported to exert beneficial effects in neurodegenerative diseases, such as Parkinson’s disease and Alzheimer’s disease. In the present study, we used immunofluorescence staining, electroretinogram (ERG) recordings and RNA-Seq to explore the effects of metformin on photoreceptor degeneration and its mechanism in rd1 mice. We found that metformin significantly reduced apoptosis in photoreceptors and delayed the degeneration of photoreceptors and rod bipolar cells in rd1 mice, thus markedly improving the visual function of rd1 mice at P14, P18, and P22 when tested with a light/dark transition test and ERG. Microglial activation in the outer nuclear layer (ONL) of the retina of rd1 mice was significantly suppressed by metformin. RNA-Seq showed that metformin markedly downregulated inflammatory genes and upregulated the expression of crystallin proteins, which have been demonstrated to be important neuroprotective molecules in the retina, revealing the therapeutic potential of metformin for RP treatment. αA-crystallin proteins were further confirmed to be involved in the neuroprotective effects of metformin in a Ca2+ ionophore-damaged 661W photoreceptor-like cell line. These data suggest that metformin exerts a protective effect in rd1 mice via both immunoregulatory and new neuroprotective mechanisms.
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Affiliation(s)
- Luodan A
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Laboratory of Molecular Developmental Biology, School of Life Sciences, Southwest University, Chongqing, China.,Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Ting Zou
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Juncai He
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Xia Chen
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Dayu Sun
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
| | - Xiaotang Fan
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University (Army Medical University), Chongqing, China
| | - Haiwei Xu
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China
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25
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Delbecq SP, Klevit RE. HSPB5 engages multiple states of a destabilized client to enhance chaperone activity in a stress-dependent manner. J Biol Chem 2018; 294:3261-3270. [PMID: 30567736 DOI: 10.1074/jbc.ra118.003156] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 12/03/2018] [Indexed: 11/06/2022] Open
Abstract
Small heat shock proteins (sHSPs) delay protein aggregation in an ATP-independent manner by interacting with client proteins that are in states susceptible to aggregation, including destabilized states related to cellular stress. Up-regulation of sHSPs under stress conditions supports their critical role in cellular viability. Widespread distribution of sHSPs in most organisms implies conservation of function, but it remains unclear whether sHSPs implement common or distinct mechanisms to delay protein aggregation. Comparisons among various studies are confounded by the use of different model client proteins, different assays for both aggregation and sHSP/client interactions, and variable experimental conditions used to mimic cellular stress. To further define sHSP/client interactions and their relevance to sHSP chaperone function, we implemented multiple strategies to characterize sHSP interactions with α-lactalbumin, a model client whose aggregation pathway is well defined. We compared the chaperone activity of human αB-crystallin (HSPB5) with HSPB5 variants that mimic states that arise under conditions of cellular stress or disease. The results show that these closely related sHSPs vary not only in their activity under identical conditions but also in their interactions with clients. Importantly, under nonstress conditions, WT HSPB5 delays client aggregation solely through transient interactions early in the aggregation pathway, whereas HSPB5 mutants that mimic stress-activated conditions can also intervene at later stages of the aggregation pathway to further delay client protein aggregation.
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Affiliation(s)
- Scott P Delbecq
- From the Department of Biochemistry, University of Washington, Seattle, Washington 98195-7350
| | - Rachel E Klevit
- From the Department of Biochemistry, University of Washington, Seattle, Washington 98195-7350
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26
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Thorn DC, Grosas AB, Mabbitt PD, Ray NJ, Jackson CJ, Carver JA. The Structure and Stability of the Disulfide-Linked γS- Crystallin Dimer Provide Insight into Oxidation Products Associated with Lens Cataract Formation. J Mol Biol 2018; 431:483-497. [PMID: 30552875 DOI: 10.1016/j.jmb.2018.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/05/2018] [Indexed: 11/18/2022]
Abstract
The reducing environment in the eye lens diminishes with age, leading to significant oxidative stress. Oxidation of lens crystallin proteins is the major contributor to their destabilization and deleterious aggregation that scatters visible light, obscures vision, and ultimately leads to cataract. However, the molecular basis for oxidation-induced aggregation is unknown. Using X-ray crystallography and small-angle X-ray scattering, we describe the structure of a disulfide-linked dimer of human γS-crystallin that was obtained via oxidation of C24. The γS-crystallin dimer is stable at glutathione concentrations comparable to those in aged and cataractous lenses. Moreover, dimerization of γS-crystallin significantly increases the protein's propensity to form large insoluble aggregates owing to non-cooperative domain unfolding, as is observed in crystallin variants associated with early-onset cataract. These findings provide insight into how oxidative modification of crystallins contributes to cataract and imply that early-onset and age-related forms of the disease share comparable development pathways.
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Affiliation(s)
- David C Thorn
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Aidan B Grosas
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Peter D Mabbitt
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Nicholas J Ray
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Colin J Jackson
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - John A Carver
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia.
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27
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Lynch JM, Li B, Katoli P, Xiang C, Leehy B, Rangaswamy N, Saenz-Vash V, Wang YK, Lei H, Nicholson TB, Meredith E, Rice DS, Prasanna G, Chen A. Binding of a glaucoma-associated myocilin variant to the αB- crystallin chaperone impedes protein clearance in trabecular meshwork cells. J Biol Chem 2018; 293:20137-20156. [PMID: 30389787 DOI: 10.1074/jbc.ra118.004325] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 10/19/2018] [Indexed: 01/09/2023] Open
Abstract
Myocilin (MYOC) was discovered more than 20 years ago and is the gene whose mutations are most commonly observed in individuals with glaucoma. Despite extensive research efforts, the function of WT MYOC has remained elusive, and how mutant MYOC is linked to glaucoma is unclear. Mutant MYOC is believed to be misfolded within the endoplasmic reticulum, and under normal physiological conditions misfolded MYOC should be retro-translocated to the cytoplasm for degradation. To better understand mutant MYOC pathology, we CRISPR-engineered a rat to have a MYOC Y435H substitution that is the equivalent of the pathological human MYOC Y437H mutation. Using this engineered animal model, we discovered that the chaperone αB-crystallin (CRYAB) is a MYOC-binding partner and that co-expression of these two proteins increases protein aggregates. Our results suggest that the misfolded mutant MYOC aggregates with cytoplasmic CRYAB and thereby compromises protein clearance mechanisms in trabecular meshwork cells, and this process represents the primary mode of mutant MYOC pathology. We propose a model by which mutant MYOC causes glaucoma, and we propose that therapeutic treatment of patients having a MYOC mutation may focus on disrupting the MYOC-CRYAB complexes.
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Affiliation(s)
- Jeffrey M Lynch
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139.
| | - Bing Li
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Parvaneh Katoli
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Chuanxi Xiang
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Barrett Leehy
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Nalini Rangaswamy
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Veronica Saenz-Vash
- Analytical Sciences and Imaging, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Y Karen Wang
- Analytical Sciences and Imaging, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Hong Lei
- Laboratory Animal Services, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Thomas B Nicholson
- Chemical Biology and Therapeutics, and Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Erik Meredith
- Global Developmental Chemistry, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Dennis S Rice
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Ganesh Prasanna
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
| | - Amy Chen
- From Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139
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28
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Abstract
Small heat shock proteins (sHsps) are a ubiquitous and ancient family of ATP-independent molecular chaperones. A key characteristic of sHsps is that they exist in ensembles of iso-energetic oligomeric species differing in size. This property arises from a unique mode of assembly involving several parts of the subunits in a flexible manner. Current evidence suggests that smaller oligomers are more active chaperones. Thus, a shift in the equilibrium of the sHsp ensemble allows regulating the chaperone activity. Different mechanisms have been identified that reversibly change the oligomer equilibrium. The promiscuous interaction with non-native proteins generates complexes that can form aggregate-like structures from which native proteins are restored by ATP-dependent chaperones such as Hsp70 family members. In recent years, this basic paradigm has been expanded, and new roles and new cofactors, as well as variations in structure and regulation of sHsps, have emerged.
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Affiliation(s)
- Martin Haslbeck
- From the Department of Chemie and Center for Integrated Protein Science, Technische Universität München, Lichtenbergstrasse 4, 85 748 Garching, Germany
| | - Sevil Weinkauf
- From the Department of Chemie and Center for Integrated Protein Science, Technische Universität München, Lichtenbergstrasse 4, 85 748 Garching, Germany
| | - Johannes Buchner
- From the Department of Chemie and Center for Integrated Protein Science, Technische Universität München, Lichtenbergstrasse 4, 85 748 Garching, Germany
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29
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Serebryany E, Yu S, Trauger SA, Budnik B, Shakhnovich EI. Dynamic disulfide exchange in a crystallin protein in the human eye lens promotes cataract-associated aggregation. J Biol Chem 2018; 293:17997-18009. [PMID: 30242128 DOI: 10.1074/jbc.ra118.004551] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/14/2018] [Indexed: 12/31/2022] Open
Abstract
Increased light scattering in the eye lens due to aggregation of the long-lived lens proteins, crystallins, is the cause of cataract disease. Several mutations in the gene encoding human γD-crystallin (HγD) cause misfolding and aggregation. Cataract-associated substitutions at Trp42 cause the protein to aggregate in vitro from a partially unfolded intermediate locked by an internal disulfide bridge, and proteomic evidence suggests a similar aggregation precursor is involved in age-onset cataract. Surprisingly, WT HγD can promote aggregation of the W42Q variant while itself remaining soluble. Here, a search for a biochemical mechanism for this interaction has revealed a previously unknown oxidoreductase activity in HγD. Using in vitro oxidation, mutational analysis, cysteine labeling, and MS, we have assigned this activity to a redox-active internal disulfide bond that is dynamically exchanged among HγD molecules. The W42Q variant acts as a disulfide sink, reducing oxidized WT and forming a distinct internal disulfide that kinetically traps the aggregation-prone intermediate. Our findings suggest a redox "hot potato" competition among WT and mutant or modified polypeptides wherein variants with the lowest kinetic stability are trapped in aggregation-prone intermediate states upon accepting disulfides from more stable variants. Such reactions may occur in other long-lived proteins that function in oxidizing environments. In these cases, aggregation may be forestalled by inhibiting disulfide flow toward mutant or damaged polypeptides.
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Affiliation(s)
- Eugene Serebryany
- From the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Shuhuai Yu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122 Jiangsu, China
| | | | - Bogdan Budnik
- Mass Spectrometry and Proteomics Resource Laboratory, Faculty of Arts and Sciences, Harvard University, Cambridge, Massachusetts 02138
| | - Eugene I Shakhnovich
- From the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138.
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30
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Liu Z, Wang C, Li Y, Zhao C, Li T, Li D, Zhang S, Liu C. Mechanistic insights into the switch of αB- crystallin chaperone activity and self-multimerization. J Biol Chem 2018; 293:14880-14890. [PMID: 30076220 DOI: 10.1074/jbc.ra118.004034] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/25/2018] [Indexed: 12/15/2022] Open
Abstract
αB-Crystallin (αBc) is a small heat shock protein that protects cells against abnormal protein aggregation and disease-related degeneration. αBc is also a major structural protein that forms polydisperse multimers that maintain the liquid-like property of the eye lens. However, the relationship and regulation of the two functions have yet to be explored. Here, by combining NMR spectroscopy and multiple biophysical approaches, we found that αBc uses a conserved β4/β8 surface of the central α-crystallin domain to bind α-synuclein and Tau proteins and prevent them from aggregating into pathological amyloids. We noted that this amyloid-binding surface can also bind the C-terminal IPI motif of αBc, which mediates αBc multimerization and weakens its chaperone activity. We further show that disruption of the IPI binding impairs αBc self-multimerization but enhances its chaperone activity. Our work discloses the structural mechanism underlying the regulation of αBc chaperone activity and self-multimerization and sheds light on the different functions of αBc in antagonizing neurodegeneration and maintaining eye lens liquidity.
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Affiliation(s)
- Zhenying Liu
- From the Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 26 Qiuyue Road, Shanghai 201210, China.,University of the Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Chuchu Wang
- From the Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 26 Qiuyue Road, Shanghai 201210, China.,University of the Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Yichen Li
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Bio-X Institutes, Shanghai Jiao Tong University, Shanghai 200030, China, and
| | - Chunyu Zhao
- From the Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 26 Qiuyue Road, Shanghai 201210, China.,University of the Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Tongzhou Li
- From the Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 26 Qiuyue Road, Shanghai 201210, China.,University of the Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Dan Li
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Bio-X Institutes, Shanghai Jiao Tong University, Shanghai 200030, China, and
| | - Shengnan Zhang
- From the Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 26 Qiuyue Road, Shanghai 201210, China,
| | - Cong Liu
- From the Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 26 Qiuyue Road, Shanghai 201210, China,
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31
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Limi S, Senecal A, Coleman R, Lopez-Jones M, Guo P, Polumbo C, Singer RH, Skoultchi AI, Cvekl A. Transcriptional burst fraction and size dynamics during lens fiber cell differentiation and detailed insights into the denucleation process. J Biol Chem 2018; 293:13176-13190. [PMID: 29959226 DOI: 10.1074/jbc.ra118.001927] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/11/2018] [Indexed: 01/05/2023] Open
Abstract
Genes are transcribed in irregular pulses of activity termed transcriptional bursts. Cellular differentiation requires coordinated gene expression; however, it is unknown whether the burst fraction (i.e. the number of active phases of transcription) or size/intensity (the number of RNA molecules produced within a burst) changes during cell differentiation. In the ocular lens, the positions of lens fiber cells correlate precisely with their differentiation status, and the most advanced cells degrade their nuclei. Here, we examined the transcriptional parameters of the β-actin and lens differentiation-specific α-, β-, and γ-crystallin genes by RNA fluorescent in situ hybridization (FISH) in the lenses of embryonic day (E) E12.5, E14.5, and E16.5 mouse embryos and newborns. We found that cellular differentiation dramatically alters the burst fraction in synchronized waves across the lens fiber cell compartment with less dramatic changes in burst intensity. Surprisingly, we observed nascent transcription of multiple genes in nuclei just before nuclear destruction. Nuclear condensation was accompanied by transfer of nuclear proteins, including histone and nonhistone proteins, to the cytoplasm. Although lens-specific deletion of the chromatin remodeler SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 5 (Smarca5/Snf2h) interfered with denucleation, persisting nuclei remained transcriptionally competent and exhibited changes in both burst intensity and fraction depending on the gene examined. Our results uncover the mechanisms of nascent transcriptional control during differentiation and chromatin remodeling, confirm the burst fraction as the major factor adjusting gene expression levels, and reveal transcriptional competence of fiber cell nuclei even as they approach disintegration.
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Affiliation(s)
| | | | | | | | | | | | - Robert H Singer
- Anatomy and Structural Biology.,Cell Biology.,Neuroscience, and
| | | | - Ales Cvekl
- From the Departments of Genetics, .,Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York 10461
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32
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Abstract
The birth of novel genes, including their cell-specific transcriptional control, is a major source of evolutionary innovation. The lens-preferred proteins, crystallins (vertebrates: α- and β/γ-crystallins), provide a gateway to study eye evolution. Diversity of crystallins was thought to originate from convergent evolution through multiple, independent formation of Pax6/PaxB-binding sites within the promoters of genes able to act as crystallins. Here, we propose that αB-crystallin arose from a duplication of small heat shock protein (Hspb1-like) gene accompanied by Pax6-site and heat shock element (HSE) formation, followed by another duplication to generate the αA-crystallin gene in which HSE was converted into another Pax6-binding site. The founding β/γ-crystallin gene arose from the ancestral Hspb1-like gene promoter inserted into a Ca2+-binding protein coding region, early in the cephalochordate/tunicate lineage. Likewise, an ancestral aldehyde dehydrogenase (Aldh) gene, through multiple gene duplications, expanded into a multigene family, with specific genes expressed in invertebrate lenses (Ω-crystallin/Aldh1a9) and both vertebrate lenses (η-crystallin/Aldh1a7 and Aldh3a1) and corneas (Aldh3a1). Collectively, the present data reconstruct the evolution of diverse crystallin gene families.
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Affiliation(s)
- Ales Cvekl
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Yilin Zhao
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Rebecca McGreal
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Qing Xie
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Xun Gu
- Program in Bioinformatics and Computational Biology, Department of Genetics, Development, and Cell Biology, Iowa State University
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York.,Department of Neurology, Albert Einstein College of Medicine, Bronx, New York.,Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
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33
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Takata T, Nakamura-Hirota T, Inoue R, Morishima K, Sato N, Sugiyama M, Fujii N. Asp 58 modulates lens αA- crystallin oligomer formation and chaperone function. FEBS J 2018; 285:2263-2277. [PMID: 29676852 DOI: 10.1111/febs.14475] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 04/02/2018] [Accepted: 04/13/2018] [Indexed: 11/28/2022]
Abstract
Senile cataract onset is caused by insolubilization of lens proteins. The lens crystallin protein family correctly orders the formation of homo- or hetero-oligomers in lens fiber cells. Because lens fiber cells do not divide, covalent post-translational modifications, such as isomerization of aspartate residues, accumulate with aging. Although many isomerization sites of αA-crystallin have been reported, their structural and functional contributions have never been identified. In this study, αA-crystallin was extracted from aged human lens and separated into each oligomeric state by size exclusion chromatography and electrophoresis. The novel combination methodology of in-solution/gel tryptic digestion with liquid chromatography equipped with mass spectrometry (LC-MS/MS) was used to evaluate the isomerization of Asp 58. The contributions of isomerization to assembly, solubility, and chaperone functions of αA-crystallin were estimated using a series of mutations of Asp 58 in αA-crystallin. The results indicated that the isomerization of Asp 58 depended on the oligomer size and age of the lens. The substitution of Asp 58 for hydrophobic residues increased αA-crystallin oligomer size and decreased solubility. All substitutions decreased the chaperone function of αA-crystallin for aggregates of bovine βL-crystallin and alcohol dehydrogenase. The data indicated that Asp 58 in αA-crystallin was critical for intermolecular interactions in the lens. Our results also suggested that LC-MS/MS-based isomerization analyses of in-gel-digested products could be useful for investigating the isomerization of Asp residues in oligomeric states. This method could also be used to analyze d/l ratios of amino acid residues in soluble protein aggregates.
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Affiliation(s)
- Takumi Takata
- Research Reactor Institute, Kyoto University, Osaka, Japan
| | | | - Rintaro Inoue
- Research Reactor Institute, Kyoto University, Osaka, Japan
| | - Ken Morishima
- Research Reactor Institute, Kyoto University, Osaka, Japan
| | - Nobuhiro Sato
- Research Reactor Institute, Kyoto University, Osaka, Japan
| | | | - Noriko Fujii
- Research Reactor Institute, Kyoto University, Osaka, Japan
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34
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Zhu XJ, Zhang KK, He WW, Du Y, Hooi M, Lu Y. Racemization at the Asp 58 residue in αA- crystallin from the lens of high myopic cataract patients. J Cell Mol Med 2017; 22:1118-1126. [PMID: 28994184 PMCID: PMC5783843 DOI: 10.1111/jcmm.13363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/19/2017] [Indexed: 01/25/2023] Open
Abstract
Post-translational modifications in lens proteins are key causal factors in cataract. As the most abundant post-translational modification in the lens, racemization may be closely related to the pathogenesis of cataract. Racemization of αA-crystallin, a crucial structural and heat shock protein in the human lens, could significantly influence its structure and function. In previous studies, elevated racemization from l-Asp 58 to d-isoAsp58 in αA-crystallin has been found in age-related cataract (ARC) lenses compared to normal aged human lenses. However, the role of racemization in high myopic cataract (HMC), which is characterized by an early onset of nuclear cataract, remains unknown. In the current study, apparently different from ARC, significantly increased racemization from l-Asp 58 to d-Asp 58 in αA-crystallin was identified in HMC lenses. The average racemization rates for each Asp isoform were calculated in ARC and HMC group. In ARC patients, the conversion of l-Asp 58 to d-isoAsp 58, up to 31.89%, accounted for the main proportion in racemization, which was in accordance with the previous studies. However, in HMC lenses, the conversion of l-Asp 58 to d-Asp 58, as high as 35.44%, accounted for the largest proportion of racemization in αA-crystallin. The different trend in the conversion of αA-crystallin by racemization, especially the elevated level of d-Asp 58 in HMC lenses, might prompt early cataractogenesis and a possible explanation of distinct phenotypes of cataract in HMC.
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Affiliation(s)
- Xiang-Jia 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
| | - Ke-Ke 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
| | - Wen-Wen He
- 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
| | - Yu Du
- 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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35
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Sagar V, Chaturvedi SK, Schuck P, Wistow G. Crystal Structure of Chicken γS- Crystallin Reveals Lattice Contacts with Implications for Function in the Lens and the Evolution of the βγ-Crystallins. Structure 2017. [PMID: 28648607 PMCID: PMC5518705 DOI: 10.1016/j.str.2017.05.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Previous attempts to crystallize mammalian γS-crystallin were unsuccessful. Native L16 chicken γS crystallized avidly while the Q16 mutant did not. The x-ray structure for chicken γS at 2.3Å resolution shows the canonical structure of the superfamily plus a well-ordered N-arm aligned with a β-sheet of a neighboring N-domain. L16 is also in a lattice contact, partially shielded from solvent. Unexpectedly, the major lattice contact matches a conserved interface (QR) in the multimeric β-crystallins. QR shows little conservation of residue contacts, except for one between symmetry-related tyrosines, but molecular dipoles for the proteins with QR show striking similarities while other γ-crystallins differ. In γS, QR has few hydrophobic contacts and features a thin layer of tightly bound water. The free energy of QR is slightly repulsive and AUC confirms no dimerization in solution. The lattice contacts suggest how γcrystallins allow close packing without aggregation in the crowded environment of the lens.
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Affiliation(s)
- Vatsala Sagar
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Building 6, Room 106, Bethesda, MD 20892, USA
| | - Sumit K Chaturvedi
- Dynamics of Macromolecular Assembly Section, LCIMB, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter Schuck
- Dynamics of Macromolecular Assembly Section, LCIMB, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | - Graeme Wistow
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Building 6, Room 106, Bethesda, MD 20892, USA.
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36
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Zhang TO, Alperstein AM, Zanni MT. Amyloid β-Sheet Secondary Structure Identified in UV-Induced Cataracts of Porcine Lenses using 2D IR Spectroscopy. J Mol Biol 2017; 429:1705-1721. [PMID: 28454743 PMCID: PMC5493149 DOI: 10.1016/j.jmb.2017.04.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 04/08/2017] [Accepted: 04/24/2017] [Indexed: 02/04/2023]
Abstract
Cataracts are formed by the aggregation of crystallin proteins in the eye lens. Many in vitro studies have established that crystallin proteins precipitate into aggregates that contain amyloid fibers when denatured, but there is little evidence that ex vivo cataracts contain amyloid. In this study, we collect two-dimensional infrared (2D IR) spectra on tissue slices of porcine eye lenses. As shown in control experiments on in vitro αB- and γD-crystallin, 2D IR spectroscopy can identify the highly ordered β-sheets typical of amyloid secondary structure even if the fibers themselves are too short to be resolved with TEM. In ex vivo experiments of acid-treated tissues, characteristic 2D IR features are observed and fibers >50nm in length are resolved by transmission electron microscopy (TEM), consistent with amyloid fibers. In UV-irradiated lens tissues, fibers are not observed with TEM, but highly ordered β-sheets of amyloid secondary structure is identified from the 2D IR spectra. The characteristic 2D IR features of amyloid β-sheet secondary structure are created by as few as four or five strands and so identify amyloid secondary structure even if the aggregates themselves are too small to be resolved with TEM. We discuss these findings in the context of the chaperone system of the lens, which we hypothesize sequesters small aggregates, thereby preventing long fibers from forming. This study expands the scope of heterodyned 2D IR spectroscopy to tissues. The results provide a link between in vitro and ex vivo studies and support the hypothesis that cataracts are an amyloid disease.
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Affiliation(s)
- Tianqi O Zhang
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
| | - Ariel M Alperstein
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
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37
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Gao M, Yang F, Zhang L, Su Z, Huang Y. Exploring the sequence-structure-function relationship for the intrinsically disordered βγ- crystallin Hahellin. J Biomol Struct Dyn 2017; 36:1171-1181. [PMID: 28393629 DOI: 10.1080/07391102.2017.1316519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
βγ-Crystallins are a superfamily of proteins containing crystallin-type Greek key motifs. Some βγ-crystallin domains have been shown to bind Ca2+. Hahellin is a newly identified intrinsically disordered βγ-crystallin domain from Hahella chejuensis. It folds into a typical βγ-crystallin structure upon Ca2+ binding and acts as a Ca2+-regulated conformational switch. Besides Hahellin, another two putative βγ-crystallins from Caulobacter crescentus and Yersinia pestis are shown to be partially disordered in their apo-form and undergo large conformational changes upon Ca2+ binding, although whether they acquire a βγ-crystallin fold is not known. The extent of conformational disorder/order of a protein is determined by its amino acid sequence. To date how this sequence-structure relationship is reflected in the βγ-crystallin superfamily has not been investigated. In this work, we comparatively studied the sequence and structure of Hahellin with those of Protein S, an ordered βγ-crystallin, via various computational biophysical techniques. We found that several factors, including presence of a C-terminal disorder prone region, high content of energetic frustrations, and low contact density, may promote the formation of the disordered state of apo-Hahellin. We also analyzed the disorder propensities for other putative disordered βγ-crystallin domains. This study provides new clues for further understanding the sequence-structure-function relationship of βγ-crystallins.
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Affiliation(s)
- Meng Gao
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Fei Yang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Lei Zhang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Zhengding Su
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Yongqi Huang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
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38
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Raju M, Santhoshkumar P, Sharma KK. Lens Endogenous Peptide αA66-80 Generates Hydrogen Peroxide and Induces Cell Apoptosis. Aging Dis 2017; 8:57-70. [PMID: 28203481 PMCID: PMC5287387 DOI: 10.14336/ad.2016.0805] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/05/2016] [Indexed: 01/27/2023] Open
Abstract
In previous studies, we reported the presence of a large number of low-molecular-weight (LMW) peptides in aged and cataract human lens tissues. Among the LMW peptides, a peptide derived from αA-crystallin, αA66-80, was found in higher concentration in aged and cataract lenses. Additional characterization of the αA66-80 peptide showed beta sheet signature, and it formed well-defined unbranched fibrils. Further experimental data showed that αA66-80 peptide binds α-crystallin, impairs its chaperone function, and attracts additional crystallin proteins to the peptide α-crystallin complex, leading to the formation of larger light scattering aggregates. It is well established that Aβ peptide exhibits cell toxicity by the generation of hydrogen peroxide. The αA66-80 peptide shares the principal properties of Aβ peptide. Therefore, the present study was undertaken to determine whether the fibril-forming peptide αA66-80 has the ability to generate hydrogen peroxide. The results show that the αA66-80 peptide generates hydrogen peroxide, in the amount of 1.2 nM H2O2 per µg of αA66-80 peptide by incubation at 37°C for 4h. We also observed cytotoxicity and apoptotic cell death in αA66-80 peptide-transduced Cos7 cells. As evident, we found more TUNEL-positive cells in αA66-80 peptide transduced Cos7 cells than in control cells, suggesting peptide-mediated cell apoptosis. Additional immunohistochemistry analysis showed the active form of caspase-3, suggesting activation of the caspase-dependent pathway during peptide-induced cell apoptosis. These results confirm that the αA66-80 peptide generates hydrogen peroxide and promotes hydrogen peroxide-mediated cell apoptosis.
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Affiliation(s)
| | | | - K Krishna Sharma
- 1Departments of Ophthalmology and; 2Biochemistry, University of Missouri School of Medicine, Columbia, MO65212, USA
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39
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Wang Z, Wang L, Huang ZX, Hu X, Liu J, Hu W, Ji W, Nie Q, Xiang JW, Chen ZG, Xiao Y, Qiang WJ, Zhu J, Gigantelli JW, Nguyen QD, Li DWC. Contrast Functions of αA- and αB- Crystallins in Cancer Development. Curr Mol Med 2016; 16:914-922. [PMID: 28017134 DOI: 10.2174/1566524016666161223110508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 10/29/2016] [Accepted: 12/12/2016] [Indexed: 11/22/2022]
Abstract
α-Crystallins, initially identified as the structural proteins of the ocular lens, belong to the small heat shock protein family. They play significant roles in maintaining the lens transparency and preventing protein aggregation. α-Crystallins exist in two isoforms: αA and αB, and they display differential tissue distribution. Their mutations are implicated in several human diseases including cardiac myopathies, neurodegenerative diseases, cataracts and various types of cancers. Increased αB expression was detected in retinoblastoma, breast cancer, glioblastoma, prostate and renal cell carcinomas, indicating its role in promoting tumor growth. A complex picture emerges for αA. Although earlier studies suggest that αA may promote cancer development, recent studies from our laboratory demonstrate that αA can act as a tumor suppressor inhibiting cell transformation and retarding cell migration through modulating MAP kinase activity. In this review, we summarize the recent progress about the functions of αA and αB in cancer development.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - D W-C Li
- Department of Ophthalmology and Visual Sciences, Stanley M. Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5540,. United States
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40
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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41
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Serebryany E, Woodard JC, Adkar BV, Shabab M, King JA, Shakhnovich EI. An Internal Disulfide Locks a Misfolded Aggregation-prone Intermediate in Cataract-linked Mutants of Human γD- Crystallin. J Biol Chem 2016; 291:19172-83. [PMID: 27417136 DOI: 10.1074/jbc.m116.735977] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Indexed: 11/06/2022] Open
Abstract
Considerable mechanistic insight has been gained into amyloid aggregation; however, a large number of non-amyloid protein aggregates are considered "amorphous," and in most cases, little is known about their mechanisms. Amorphous aggregation of γ-crystallins in the eye lens causes cataract, a widespread disease of aging. We combined simulations and experiments to study the mechanism of aggregation of two γD-crystallin mutants, W42R and W42Q: the former a congenital cataract mutation, and the latter a mimic of age-related oxidative damage. We found that formation of an internal disulfide was necessary and sufficient for aggregation under physiological conditions. Two-chain all-atom simulations predicted that one non-native disulfide in particular, between Cys(32) and Cys(41), was likely to stabilize an unfolding intermediate prone to intermolecular interactions. Mass spectrometry and mutagenesis experiments confirmed the presence of this bond in the aggregates and its necessity for oxidative aggregation under physiological conditions in vitro Mining the simulation data linked formation of this disulfide to extrusion of the N-terminal β-hairpin and rearrangement of the native β-sheet topology. Specific binding between the extruded hairpin and a distal β-sheet, in an intermolecular chain reaction similar to domain swapping, is the most probable mechanism of aggregate propagation.
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Affiliation(s)
- Eugene Serebryany
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
| | - Jaie C Woodard
- the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Bharat V Adkar
- the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Mohammed Shabab
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
| | - Jonathan A King
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and
| | - Eugene I Shakhnovich
- the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
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42
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Scholl ZN, Li Q, Yang W, Marszalek PE. Single-molecule Force Spectroscopy Reveals the Calcium Dependence of the Alternative Conformations in the Native State of a βγ- Crystallin Protein. J Biol Chem 2016; 291:18263-75. [PMID: 27378818 DOI: 10.1074/jbc.m116.729525] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Indexed: 12/30/2022] Open
Abstract
Although multidomain proteins predominate the proteome of all organisms and are expected to display complex folding behaviors and significantly greater structural dynamics as compared with single-domain proteins, their conformational heterogeneity and its impact on their interaction with ligands are poorly understood due to a lack of experimental techniques. The multidomain calcium-binding βγ-crystallin proteins are particularly important because their deterioration and misfolding/aggregation are associated with melanoma tumors and cataracts. Here we investigate the mechanical stability and conformational dynamics of a model calcium-binding βγ-crystallin protein, Protein S, and elaborate on its interactions with calcium. We ask whether domain interactions and calcium binding affect Protein S folding and potential structural heterogeneity. Our results from single-molecule force spectroscopy show that the N-terminal (but not the C-terminal) domain is in equilibrium with an alternative conformation in the absence of Ca(2+), which is mechanically stable in contrast to other proteins that were observed to sample a molten globule under similar conditions. Mutagenesis experiments and computer simulations reveal that the alternative conformation of the N-terminal domain is caused by structural instability produced by the high charge density of a calcium binding site. We find that this alternative conformation in the N-terminal domain is diminished in the presence of calcium and can also be partially eliminated with a hitherto unrecognized compensatory mechanism that uses the interaction of the C-terminal domain to neutralize the electronegative site. We find that up to 1% of all identified multidomain calcium-binding proteins contain a similarly highly charged site and therefore may exploit a similar compensatory mechanism to prevent structural instability in the absence of ligand.
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Affiliation(s)
| | - Qing Li
- the Department of Mechanical Engineering and Materials Science, and
| | - Weitao Yang
- the Department of Chemistry, Duke University, Durham, North Carolina 27708
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43
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Gupta MK, McLendon PM, Gulick J, James J, Khalili K, Robbins J. UBC9-Mediated Sumoylation Favorably Impacts Cardiac Function in Compromised Hearts. Circ Res 2016; 118:1894-905. [PMID: 27142163 DOI: 10.1161/circresaha.115.308268] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 05/03/2016] [Indexed: 12/25/2022]
Abstract
RATIONALE SUMOylation plays an important role in cardiac function and can be protective against cardiac stress. Recent studies show that SUMOylation is an integral part of the ubiquitin proteasome system, and expression of the small ubiquitin-like modifier (SUMO) E2 enzyme UBC9 improves cardiac protein quality control. However, the precise role of SUMOylation on other protein degradation pathways, particularly autophagy, remains undefined in the heart. OBJECTIVE To determine whether SUMOylation affects cardiac autophagy and whether this effect is protective in a mouse model of proteotoxic cardiac stress. METHODS AND RESULTS We modulated expression of UBC9, a SUMO E2 ligase, using gain- and loss-of-function in neonatal rat ventricular cardiomyocytes. UBC9 expression seemed to directly alter autophagic flux. To confirm this effect in vivo, we generated transgenic mice overexpressing UBC9 in cardiomyocytes. These mice have an increased level of SUMOylation at baseline and, in confirmation of the data obtained from neonatal rat ventricular cardiomyocytes, demonstrated increased autophagy, suggesting that increased UBC9-mediated SUMOylation is sufficient to upregulate cardiac autophagy. Finally, we tested the protective role of SUMOylation-mediated autophagy by expressing UBC9 in a model of cardiac proteotoxicity, induced by cardiomyocyte-specific expression of a mutant α-B-crystallin, mutant CryAB (CryAB(R120G)), which shows impaired autophagy. UBC9 overexpression reduced aggregate formation, decreased fibrosis, reduced hypertrophy, and improved cardiac function and survival. CONCLUSIONS The data showed that increased UBC9-mediated SUMOylation is sufficient to induce relatively high levels of autophagy and may represent a novel strategy for increasing autophagic flux and ameliorating morbidity in proteotoxic cardiac disease.
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Affiliation(s)
- Manish K Gupta
- From the Department of Neuroscience, Temple University, Philadelphia, PA (M.K.G., K.K.); and Department of Pediatrics, The Heart Institute, The Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.M.M., J.G., J.J, J.R.)
| | - Patrick M McLendon
- From the Department of Neuroscience, Temple University, Philadelphia, PA (M.K.G., K.K.); and Department of Pediatrics, The Heart Institute, The Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.M.M., J.G., J.J, J.R.)
| | - James Gulick
- From the Department of Neuroscience, Temple University, Philadelphia, PA (M.K.G., K.K.); and Department of Pediatrics, The Heart Institute, The Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.M.M., J.G., J.J, J.R.)
| | - Jeanne James
- From the Department of Neuroscience, Temple University, Philadelphia, PA (M.K.G., K.K.); and Department of Pediatrics, The Heart Institute, The Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.M.M., J.G., J.J, J.R.)
| | - Kamel Khalili
- From the Department of Neuroscience, Temple University, Philadelphia, PA (M.K.G., K.K.); and Department of Pediatrics, The Heart Institute, The Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.M.M., J.G., J.J, J.R.)
| | - Jeffrey Robbins
- From the Department of Neuroscience, Temple University, Philadelphia, PA (M.K.G., K.K.); and Department of Pediatrics, The Heart Institute, The Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.M.M., J.G., J.J, J.R.).
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Abstract
Cataract, a major cause of visual impairment worldwide, is a common disease of the eye lens related to protein aggregation. Several factors including the exposure of ultraviolet irradiation and possibly acidic condition may induce the unfolding and subsequent aggregation of the crystallin proteins leading to crystalline lens opacification. Human γD-crystallin (HγDC), a 173 residue monomeric protein, abundant in the nucleus of the human eye lens, has been shown to aggregate and form amyloid fibrils under acidic conditions and that this aggregation route is thought to be a potential initiation pathway for the onset of age-related nuclear cataract. However, the underlying mechanism of fibril formation remains elusive. This report is aimed at examining the structural changes and possible amyloid fibril formation pathway of HγDC using molecular dynamics and molecular docking simulations. Our findings demonstrated that incubation of HγDC under the acidic condition redistributes the protein surface charges and affects the protein interaction with its surrounding solvent environment. This brings about a twist motion in the overall tertiary structure that gives rise to newly formed anti-parallel β-strands in the C-terminal flexible loop regions. The change in protein structural conformation also involves an alteration in specific salt-bridge interactions. Altogether, these findings revealed a plausible mechanism for amyloid fibril formation of HγDC that is important to the early stages of HγDC aggregation involved in cataractogenesis.
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Affiliation(s)
- Chih-Kai Chang
- a Department of Chemical Engineering , National Taiwan University , Taipei 10617 , Taiwan
| | - Steven S-S Wang
- a Department of Chemical Engineering , National Taiwan University , Taipei 10617 , Taiwan
| | - Chun-Hsien Lo
- a Department of Chemical Engineering , National Taiwan University , Taipei 10617 , Taiwan
| | - Hsiang-Chun Hsiao
- a Department of Chemical Engineering , National Taiwan University , Taipei 10617 , Taiwan
| | - Josephine W Wu
- b Department of Optometry, Central Taiwan University of Science and Technology , Taichung 40601 , Taiwan
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45
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Serebryany E, Takata T, Erickson E, Schafheimer N, Wang Y, King JA. Aggregation of Trp > Glu point mutants of human gamma-D crystallin provides a model for hereditary or UV-induced cataract. Protein Sci 2016; 25:1115-28. [PMID: 26991007 DOI: 10.1002/pro.2924] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/09/2016] [Accepted: 03/10/2016] [Indexed: 12/21/2022]
Abstract
Numerous mutations and covalent modifications of the highly abundant, long-lived crystallins of the eye lens cause their aggregation leading to progressive opacification of the lens, cataract. The nature and biochemical mechanisms of the aggregation process are poorly understood, as neither amyloid nor native-state polymers are commonly found in opaque lenses. The βγ-crystallin fold contains four highly conserved buried tryptophans, which can be oxidized to more hydrophilic products, such as kynurenine, upon UV-B irradiation. We mimicked this class of oxidative damage using Trp→Glu point mutants of human γD-crystallin. Such substitutions may represent a model of UV-induced photodamage-introduction of a charged group into the hydrophobic core generating "denaturation from within." The effects of Trp→Glu substitutions were highly position dependent. While each was destabilizing, only the two located in the bottom of the double Greek key fold-W42E and W130E-yielded robust aggregation of partially unfolded intermediates at 37°C and pH 7. The αB-crystallin chaperone suppressed aggregation of W130E, but not W42E, indicating distinct aggregation pathways from damage in the N-terminal vs C-terminal domain. The W130E aggregates had loosely fibrillar morphology, yet were nonamyloid, noncovalent, showed little surface hydrophobicity, and formed at least 20°C below the melting temperature of the native β-sheets. These features are most consistent with domain-swapped polymerization. Aggregation of partially destabilized crystallins under physiological conditions, as occurs in this class of point mutants, could provide a simple in vitro model system for drug discovery and optimization.
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Affiliation(s)
- Eugene Serebryany
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Takumi Takata
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Erika Erickson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Nathaniel Schafheimer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Yongting Wang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
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Chen Y, Sagar V, Len HS, Peterson K, Fan J, Mishra S, McMurtry J, Wilmarth PA, David LL, Wistow G. γ- Crystallins of the chicken lens: remnants of an ancient vertebrate gene family in birds. FEBS J 2016; 283:1516-30. [PMID: 26913478 DOI: 10.1111/febs.13689] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/02/2016] [Accepted: 02/18/2016] [Indexed: 11/30/2022]
Abstract
γ-Crystallins, abundant proteins of vertebrate lenses, were thought to be absent from birds. However, bird genomes contain well-conserved genes for γS- and γN-crystallins. Although expressed sequence tag analysis of chicken eye found no transcripts for these genes, RT-PCR detected spliced transcripts for both genes in chicken lens, with lower levels in cornea and retina/retinal pigment epithelium. The level of mRNA for γS in chicken lens was relatively very low even though the chicken crygs gene promoter had lens-preferred activity similar to that of mouse. Chicken γS was detected by a peptide antibody in lens, but not in other ocular tissues. Low levels of γS and γN proteins were detected in chicken lens by shotgun mass spectroscopy. Water-soluble and water-insoluble lens fractions were analyzed and 1934 proteins (< 1% false discovery rate) were detected, increasing the known chicken lens proteome 30-fold. Although chicken γS is well conserved in protein sequence, it has one notable difference in leucine 16, replacing a surface glutamine conserved in other γ-crystallins, possibly affecting solubility. However, L16 and engineered Q16 versions were both highly soluble and had indistinguishable circular dichroism, tryptophan fluorescence and heat stability (melting temperature Tm ~ 65 °C) profiles. L16 has been present in birds for over 100 million years and may have been adopted for a specific protein interaction in the bird lens. However, evolution has clearly reduced or eliminated expression of ancestral γ-crystallins in bird lenses. The conservation of genes for γS- and γN-crystallins suggests they may have been preserved for reasons unrelated to the bulk properties of the lens.
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Affiliation(s)
- Yingwei Chen
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Vatsala Sagar
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Hoay-Shuen Len
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Katherine Peterson
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jianguo Fan
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sanghamitra Mishra
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - John McMurtry
- USDA, ARS, Southern Plains Area, East College Station, TX, USA
| | - Phillip A Wilmarth
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Larry L David
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Graeme Wistow
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
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Rakete S, Nagaraj RH. Identification of Kynoxazine, a Novel Fluorescent Product of the Reaction between 3-Hydroxykynurenine and Erythrulose in the Human Lens, and Its Role in Protein Modification. J Biol Chem 2016; 291:9596-609. [PMID: 26941078 DOI: 10.1074/jbc.m116.716621] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Indexed: 11/06/2022] Open
Abstract
Kynurenine pathway metabolites and ascorbate degradation products are present in human lenses. In this study, we showed that erythrulose, a major ascorbate degradation product, reacts spontaneously with 3-hydroxykynurenine to form a fluorescent product. Structural characterization of the product revealed it to be 2-amino-4-(2-hydroxy-3-(2-hydroxyethyl)-2H-benzo[b][1,4]oxazin-5-yl)-4-oxobutanoic acid, which we named kynoxazine. Unlike 3-hydroxykynurenine, 3-hydroxykynurenine glucoside and kynurenine were unable to form a kynoxazine-like compound, which suggested that the aminophenol moiety in 3-hydroxykynurenine is essential for the formation of kynoxazine. This reasoning was confirmed using a model compound, 1-(2-amino-3-hydroxyphenyl)ethan-1-one, which is an aminophenol lacking the amino acid moiety of 3-hydroxykynurenine. Ultra-performance liquid chromatography-tandem mass spectrometry analyses showed that kynoxazine is present in the human lens at levels ranging from 0 to 64 pmol/mg lens. Kynoxazine as well as erythrulose degraded under physiological conditions to generate 3-deoxythreosone, which modified and cross-linked proteins through the formation of an arginine adduct, 3-deoxythreosone-derived hydroimidazolone, and a lysine-arginine cross-linking adduct, 3-deoxythreosone-derived hydroimidazolimine cross-link. Ultra-performance liquid chromatography-tandem mass spectrometry quantification showed that 32-169 pmol/mg protein of 3-deoxythreosone-derived hydroimidazolone and 1.1-11.2 pmol/mg protein of 3-deoxythreosone-derived hydroimidazolimine cross-link occurred in aging lenses. Taken together, these results demonstrate a novel biochemical mechanism by which ascorbate oxidation and the kynurenine pathway intertwine, which could promote protein modification and cross-linking in aging human lenses.
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Affiliation(s)
- Stefan Rakete
- From the Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Ram H Nagaraj
- From the Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado 80045
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Xie Q, McGreal R, Harris R, Gao CY, Liu W, Reneker LW, Musil LS, Cvekl A. Regulation of c-Maf and αA- Crystallin in Ocular Lens by Fibroblast Growth Factor Signaling. J Biol Chem 2015; 291:3947-58. [PMID: 26719333 DOI: 10.1074/jbc.m115.705103] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Indexed: 12/20/2022] Open
Abstract
Fibroblast growth factor (FGF) signaling regulates a multitude of cellular processes, including cell proliferation, survival, migration, and differentiation. In the vertebrate lens, FGF signaling regulates fiber cell differentiation characterized by high expression of crystallin proteins. However, a direct link between FGF signaling and crystallin gene transcriptional machinery remains to be established. Previously, we have shown that the bZIP proto-oncogene c-Maf regulates expression of αA-crystallin (Cryaa) through binding to its promoter and distal enhancer, DCR1, both activated by FGF2 in cell culture. Herein, we identified and characterized a novel FGF2-responsive region in the c-Maf promoter (-272/-70, FRE). Both c-Maf and Cryaa regulatory regions contain arrays of AP-1 and Ets-binding sites. Chromatin immunoprecipitation (ChIP) assays established binding of c-Jun (an AP-1 factor) and Etv5/ERM (an Ets factor) to these regions in lens chromatin. Analysis of temporal and spatial expression of c-Jun, phospho-c-Jun, and Etv5/ERM in wild type and ERK1/2 deficient lenses supports their roles as nuclear effectors of FGF signaling in mouse embryonic lens. Collectively, these studies show that FGF signaling up-regulates expression of αA-crystallin both directly and indirectly via up-regulation of c-Maf. These molecular mechanisms are applicable for other crystallins and genes highly expressed in terminally differentiated lens fibers.
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Affiliation(s)
- Qing Xie
- From the Departments of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Rebecca McGreal
- From the Departments of Ophthalmology and Visual Sciences and
| | - Raven Harris
- Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Chun Y Gao
- Laboratory of Molecular and Developmental Biology, National Eye Institute, Bethesda, Maryland 20892
| | - Wei Liu
- From the Departments of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Lixing W Reneker
- Department of Ophthalmology, Mason Eye Institute, University of Missouri, Columbia, Missouri 65212, and
| | - Linda S Musil
- Department of Biochemistry and Molecular Biology, Oregon Health Science University, Portland, Oregon 97239
| | - Ales Cvekl
- From the Departments of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, New York 10461,
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49
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Garcia-Manyes S, Giganti D, Badilla CL, Lezamiz A, Perales-Calvo J, Beedle AEM, Fernández JM. Single-molecule Force Spectroscopy Predicts a Misfolded, Domain-swapped Conformation in human γD- Crystallin Protein. J Biol Chem 2015; 291:4226-35. [PMID: 26703476 PMCID: PMC4759196 DOI: 10.1074/jbc.m115.673871] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Indexed: 12/30/2022] Open
Abstract
Cataract is a protein misfolding disease where the size of the aggregate is directly related to the severity of the disorder. However, the molecular mechanisms that trigger the onset of aggregation remain unknown. Here we use a combination of protein engineering techniques and single-molecule force spectroscopy using atomic force microscopy to study the individual unfolding pathways of the human γD-crystallin, a multidomain protein that must remain correctly folded during the entire lifetime to guarantee lens transparency. When stretching individual polyproteins containing two neighboring HγD-crystallin monomers, we captured an anomalous misfolded conformation in which the β1 and β2 strands of the N terminus domain of two adjacent monomers swap. This experimentally elusive domain-swapped conformation is likely to be responsible for the increase in molecular aggregation that we measure in vitro. Our results demonstrate the power of force spectroscopy at capturing rare misfolded conformations with potential implications for the understanding of the molecular onset of protein aggregation.
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Affiliation(s)
- Sergi Garcia-Manyes
- From the Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London WC2R 2LS, United Kingdom and
| | - David Giganti
- the Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Carmen L Badilla
- the Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Ainhoa Lezamiz
- From the Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London WC2R 2LS, United Kingdom and
| | - Judit Perales-Calvo
- From the Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London WC2R 2LS, United Kingdom and
| | - Amy E M Beedle
- From the Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, London WC2R 2LS, United Kingdom and
| | - Julio M Fernández
- the Department of Biological Sciences, Columbia University, New York, New York 10027
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50
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Rajagopal P, Liu Y, Shi L, Clouser AF, Klevit RE. Structure of the α- crystallin domain from the redox-sensitive chaperone, HSPB1. J Biomol NMR 2015; 63:223-8. [PMID: 26243512 PMCID: PMC4589510 DOI: 10.1007/s10858-015-9973-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/27/2015] [Indexed: 05/27/2023]
Abstract
Small heat shock proteins (sHSP) are a class of ATP-independent protein chaperones found throughout nature. They share a common ability to maintain partly unfolded proteins in soluble states under cellular stress conditions. All sHSPs contain a central domain called the α-crystallin domain (ACD); the domain is found in all sHSPs and in no other proteins and therefore defines the family. Though most sHSPs form large, often polydisperse oligomers from varying numbers of subunits, the ACD is both necessary and sufficient for formation of a dimer, the fundamental building block for oligomers. HSPB1 (also known as Hsp27) is unique among the ten human sHSPs because it contains a Cys residue in its dimer interface. HSPB1 is highly expressed under conditions of oxidative stress and is proposed to serve as a redox-sensitive chaperone. HSPB1 residue Cys137 has been proposed to modulate function by existing in either its oxidized (disulfide) or reduced (thiol) form (Chalova et al 2014). Here we report the solution-state NMR structure of oxidized HSPB1-ACD and compare it to a previously determined crystal structure of the reduced state. Formation of the disulfide-bond across the dimer interface yields a locked dimer structure with increased accessible hydrophobic surface. In the context of full-length HSPB1 oligomers, oxidation of Cys137 is associated with enhanced ability to bind the hydrophobic dye, 8-Anilinonapthalene-1-sulfonic-acid, implying an increased ability to interact with client proteins under oxidative stress.
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Affiliation(s)
- Ponni Rajagopal
- Department of Biochemistry, University of Washington, Seattle, WA, 98195-7350, USA
| | - Ying Liu
- Department of Biochemistry, University of Washington, Seattle, WA, 98195-7350, USA
| | - Lei Shi
- Department of Biochemistry, University of Washington, Seattle, WA, 98195-7350, USA
| | - Amanda F Clouser
- Department of Biochemistry, University of Washington, Seattle, WA, 98195-7350, USA
| | - Rachel E Klevit
- Department of Biochemistry, University of Washington, Seattle, WA, 98195-7350, USA.
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