Abstract
Purpose: :
To investigate the in vitro gene and protein expression of alpha (α) – crystallins (αA– and αB–) in the retinal pigment epithelium (RPE) and neural retina under sublethal treatment with the oxidative stressors, hydrogen peroxide (H2O2) and tert–butylhydroperoxide (t–BOOH).
Methods: :
Initial studies evaluated the baseline expression of α–crystallins in four RPE cell–types (isolated cultured human primary RPE, freshly isolated RPE, the ARPE–19 and mouse RPE) and neural retina (human and mouse) by isolating total RNA and protein in preparation for RT–PCR and Western Blotting with α–crystallin–specific antibodies, respectively. Monolayer cultures of ARPE–19 cells and mouse retinal explants were exposed to sub–lethal levels (0.1 and 10µM) of the oxidative stressors, H2O2 and t–BOOH and changes in mRNA or protein expression of the α–crystallins was analyzed.
Results: :
αB–crystallin was constitutively expressed in cultured primary RPE cells, freshly isolated RPE and the ARPE–19 cells. αA–crystallin was not found to be expressed in the RPE but was found in both human and mouse retinal tissue. RT–PCR and Western blot analysis of ARPE–19 cells treated with H2O2 or t–BOOH oxidative stressors demonstrated a time–dependent upregulation of αB–crystallin up to 24 hours.. Mouse retinal explants treated with oxidative stressors revealed upregulation of both αA– and αB–crystallin proteins.
Conclusions: :
The data obtained from this work reveals that of the two families of α–crystallins, only αB–crystallin appears to be expressed in the RPE while both αA– and αB–crystallin are expressed in human and mouse neural retinal tissue. Expression of α–crystallin is upregulated on exposure to oxidative stressors indicating that the α–crystallins play a role in protection against oxidative stress.
Keywords: oxidation/oxidative or free radical damage • retinal pigment epithelium