Sensitization of RPE cells by alphaB-crystallin siRNA to SAHA-induced stage 1 apoptosis through abolishing the association of alphaB-crystallin with HDAC1 in SC35 speckles.

Purpose: To better understand the mechanism underlying the anti-apoptotic activity of alphaB-crystallin in RPE cells.

Methods: Cells of the human retinal pigment epithelial line ARPE-19 were treated with a histone deacetylase inhibitor (HDACI), suberoylanilide hydroxamic acid (SAHA), with or without alphaB-crystallin siRNA. To examine the mechanism underlying the cell death induced in ARPE-19 cells, nuclear staining, flow cytometry, DNA electrophoresis, pulse field gel electrophoresis, Western blot analysis, confocal microscopy, and coimmunoprecipitation assay were undertaken.

Results: The present study demonstrated that an HDACI, SAHA, at the usual doses or the silencing of alphaB-crystallin by siRNA alone did not effectively induce apoptosis in ARPE-19 cells. Silencing of alphaB-crystallin likely abolishes the anti-apoptotic activity of alphaB-crystallin. The data indicated that silencing of alphaB-crystallin sensitizes ARPE19 cells to SAHA-induced apoptosis and leads them to stage 1 apoptosis. alphaB-Crystallin associates with HDAC1 on SC35 speckles, and silencing of alphaB-crystallin abolishes this association, resulting in the induction of apoptosis. The data indicated that the association between alphaB-crystallin and HDAC1 on SC35 speckles plays a pivotal role in anti-apoptotic activity.

Conclusions: Knockout of alphaB-crystallin may be a promising new approach to enhance therapeutic potency for proliferative vitreoretinopathy without compromising efficacy.