title: Alpha-crystallin-mediated protection of lens cells against heat and oxidative stress-induced cell death.
abstract: In addition to their key role as structural lens proteins, α-crystallins also appear to confer protection against many eye diseases, including cataract, retinitis pigmentosa, and macular degeneration. Exogenous recombinant α-crystallin proteins were examined for their ability to prevent cell death induced by heat or oxidative stress in a human lens epithelial cell line (HLE-B3). Wild type αA- or αB-crystallin (WT-αA and WT-αB) and αA- or αB-crystallins, modified by the addition of a cell penetration peptide (CPP) designed to enhance the uptake of proteins into cells (gC-αB, TAT-αB, gC-αA), were produced by recombinant methods. In vitro chaperone-like assays were used to assay the ability of α-crystallins to protect client proteins from chemical or heat induced aggregation. In vivo viability assays were performed in HLE-B3 to determine whether pre-treatment with α-crystallins reduced death after exposure to oxidative or heat stress. Most of the five recombinant α-crystallin proteins tested conferred some in vitro protection from protein aggregation, with the greatest effect seen with WT-αB and gC-αB. All α-crystallins displayed significant protection to oxidative stress induced cell death, while only the αB-crystallins reduced cell death induced by thermal stress. Our findings indicate that the addition of the gC tag enhanced the protective effect of αB-crystallin against oxidative but not thermally-induced cell death. In conclusion, modifications that increase the uptake of α-crystallin proteins into cells, without destroying their chaperone-like activity and anti-apoptotic functions, create the potential to use these proteins therapeutically.
authors.affiliation: University of Colorado Denver School of Medicine, Department of Ophthalmology, Aurora, CO, USA.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Christopher
authors.affiliation: University of Colorado Denver School of Medicine, Department of Ophthalmology, Aurora, CO, USA.
authors.forename: Michelle G
authors.initials: MG
authors.lastname: Pedler
authors.affiliation: University of Colorado Denver School of Medicine, Department of Ophthalmology, Aurora, CO, USA.
authors.forename: Biehuoy
authors.initials: B
authors.lastname: Shieh
authors.affiliation: University of Colorado Denver School of Medicine, Department of Ophthalmology, Aurora, CO, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Ammar
authors.affiliation: University of Colorado Denver School of Medicine, Department of Ophthalmology, Aurora, CO, USA.
authors.forename: J Mark
authors.initials: JM
authors.lastname: Petrash
authors.affiliation: University of Colorado Denver School of Medicine, Department of Ophthalmology, Aurora, CO, USA. Electronic address: niklaus.mueller@ucdenver.edu.
authors.forename: Niklaus H
authors.initials: NH
authors.lastname: Mueller
mesh_terms: D000449:Aldehyde Reductase / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D057846:Cell-Penetrating Peptides / Q000494:pharmacology; D003459:Crystallins / Q000378:metabolism / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects*; D006358:Hot Temperature; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology*; D018384:Oxidative Stress / Q000187:drug effects*; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000494:pharmacology / Q000633:toxicity; D038203:alpha-Crystallin B Chain / Q000494:pharmacology*
chemical_list: C511246:CRYAA protein, human; C059215:CRYAB protein, human; D057846:Cell-Penetrating Peptides; D003459:Crystallins; D011994:Recombinant Proteins; D038203:alpha-Crystallin B Chain; D000449:Aldehyde Reductase
keywords: Alpha crystallin; Apoptosis; Lens; Small heat shock protein