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A. Banh, J.G. Sivak, M.M. Vijayan; The Possible Roles of Hsp70 and Alpha Crystallin in Bovine Lenses During Temperature Stress . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2367.
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Purpose:The chaperone actions of alpha crystallin (α) and heat shock protein 70 (Hsp70) may be involved in maintaining lens transparency during thermal stress. The purpose of this research was to examine whether prior heat shock treatment of lenses can modify cold cataract induction. Methods:A scanning laser instrument was used measure optical performance of 18 week old, 2 year old and 10 year old bovine lenses. The lenses of each age group were scanned initially at 37 degrees Celsius. One group, control lenses, were transferred into a modified glass culture cell and subjected to one cooling and warming cycle. The temperature cycle inside the cell started at 37 degrees then slowly cooled to 4 degrees and then warmed back up to 37 degrees. A group of heat shock lenses were subjected to an hour of heat stress at 42 degrees (5 degrees above incubation temperature). After being stabilized for 4 hours at 37 degrees, these lenses were also subjected to a cooling and warming cycle. After a cooling and warming cycle lens tissue samples were use to perform Western blot analysis. The 2 years old lenses were used for Hsp70 detection, while the 18 weeks and 10 years old lenses were used for an age study and the detection of αA-, αB- and γ-crystallins. Results:The decrease in relative light transmittance during cold cataract varies for each group of lenses, with the greatest decrease in heat shock groups and the least in control groups. Therefore there is both a treatment and a temperature effect (p<0.05) in light transmittance. Western blot results show an increase of Hsp70 in the urea soluble lens fractions. The results from αA- and αB- crystallin detection indicate an age effect between the heat shock groups and no treatment effect overall. Young control bovine lenses have the most γ-crystallin and older heat shock lenses have the lowest amount of γ-crystallin. The accumulation of γ-crystallin in the bovine lens nucleus demonstrates the most prominent change between age groups (young and old) and treatment groups (control and heat shock). There is a general decrease in γ-crystallin accumulation in heat shock lenses (young and old) when compared to the control lenses (young and old). Conclusions:Results of this study show an age effect on the cold cataract phenomenon in that young lenses are more affected by heat shock treatment and show more prominent cold cataract formation. Heat shock treatment may cause increased protein-protein interaction (interaction between α-crystallin and γ-crystallin, and also α-crystallin and Hsp70) that results in increased light scattering.
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