Antiapoptotic properties of α-crystallin-derived peptide chaperones and characterization of their uptake transporters in human RPE cells

• Published in: Investigative ophthalmology & visual science Vol. 54; no. 4; pp. 2787 - 2798
• Main Authors: Sreekumar, Parameswaran G, Chothe, Paresh, Sharma, Krishna K, Baid, Rinku, Kompella, Uday, Spee, Christine, Kannan, Nandini, Manh, Christina, Ryan, Stephen J, Ganapathy, Vadivel, Kannan, Ram, Hinton, David R
• Format: Journal Article
• Language: English
• Published: United States The Association for Research in Vision and Ophthalmology 17-04-2013
• Subjects: alpha-Crystallin A Chain - physiology; alpha-Crystallin B Chain - physiology; Apoptosis - drug effects; Apoptosis Regulatory Proteins - physiology; Caspase 3 - metabolism; Cell Line; Dose-Response Relationship, Drug; Fluorescent Antibody Technique, Indirect; Humans; Hydrogen Peroxide - toxicity; Membrane Transport Proteins - metabolism; Molecular Chaperones - physiology; Oxidants - toxicity; Oxidative Stress - drug effects; Peptides - physiology; Recombinant Proteins; Retinal Pigment Epithelium - cytology; Retinal Pigment Epithelium - metabolism; Time Factors
• ISSN: 1552-5783; 0146-0404; 1552-5783
• DOI: 10.1167/iovs.12-11571

The chaperone proteins, α-crystallins, also possess antiapoptotic properties. The purpose of the present study was to investigate whether 19 to 20-mer α-crystallin-derived mini-chaperone peptides (α-crystallin mini-chaperone) are antiapoptotic, and to identify their putative transporters in human fetal RPE (hfRPE) cells.
Cell death and caspase-3 activation induced by oxidative stress were quantified in early passage hfRPE cells in the presence of 19 to 20-mer αA- or αB-crystallin-derived or scrambled peptides. Cellular uptake of fluorescein-labeled, α-crystallin-derived mini-peptides and recombinant full-length αB-crystallin was determined in confluent hfRPE. The entry mechanism in hfRPE cells for α-crystallin mini-peptides was investigated. The protective role of polycaprolactone (PCL) nanoparticle encapsulated αB-crystallin mini-chaperone peptides from H2O2-induced cell death was studied.
Primary hfRPE cells exposed to oxidative stress and either αA- or αB-crystallin mini-chaperones remained viable and showed marked inhibition of both cell death and activation of caspase-3. Uptake of full-length αB-crystallin was minimal while a time-dependent uptake of αB-crystallin-derived peptide was observed. The mini-peptides entered the hfRPE cells via the sodium-coupled oligopeptide transporters 1 and 2 (SOPT1, SOPT2). PCL nanoparticles containing αB-crystallin mini-chaperone were also taken up and protected hfRPE from H2O2-induced cell death at significantly lower concentrations than free αB-crystallin mini-chaperone peptide.
αA- and αB-crystallin mini-chaperones offer protection to hfRPE cells and inhibit caspase-3 activation. The oligopeptide transporters SOPT1 and SOPT2 mediate the uptake of these peptides in RPE cells. Nanodelivery of αB-crystallin-derived mini-chaperone peptide offers an alternative approach for protection of hfRPE cells from oxidant injury.