Tissue localization and solubilities of αA-crystallin and its numerous C-terminal truncation products in pre- and postcataractous ICR/f rat lenses.

Stella DR, Floyd KA, Grey AC, Renfrow MB, Schey KL, Barnes S
Invest Ophthalmol Vis Sci. 2010 51 (10): 5153-61

PMID: 20435586 · PMCID: PMC3066599 · DOI:10.1167/iovs.10-5302

PURPOSE - To investigate the tissue distribution and solubilities of various αA-crystallin truncation products in the cataractous ICR/f rat model.

METHODS - Rat lenses from precataractous (21-day) and postcataractous (100-day) ICR/f rats were sectioned and applied to a matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) target plate. Mass spectrometry images were collected to obtain a macromolecular profile of the abundant lens proteins. Separately, age-matched lenses were extracted into water-soluble (WS) and water-insoluble/urea-soluble (WI-US) fractions and subjected to MALDI-TOF mass spectrometry to correlate the protein solubilities with the imaging data. Protein identities were assigned by using a top-down proteomics approach on a high-resolution mass spectrometer.

RESULTS - Ten novel αA-crystallin truncation products were identified, along with six previously known αA-crystallin truncation products. Nearly all truncations exhibited nuclear localization, with larger truncated products displaying a ringlike localization that progressed outward toward the extranuclear, cortical region. The distributions were similar in both ages with the only significant difference being the amount of tissue area encompassed by a particular species with increasing age. Almost all nuclear products fractionated into the WI-US fraction, whereas the five largest extranuclear species exhibited mixed solubility.

CONCLUSIONS - A successful methodology for the sectioning and imaging of pre- and postcataractous ICR/f rat lenses has been established. Data collected from these analyses indicate that there are multiple αA-crystallin truncation products present in both pre- and postcataractous rats. Furthermore, these species have defined lenticular localizations and unique solubilities that may be a consequence of lens development and protein function within the lens environment.

MeSH Terms (14)

alpha-Crystallin A Chain Animals Cataract Chromatography, High Pressure Liquid Disease Models, Animal Fourier Analysis Lens, Crystalline Peptide Fragments Proteomics Rats Rats, Wistar Solubility Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization Tissue Distribution

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