Abstract
Purpose: :
To investigate the role of the autophagy gene Atg5 in controlling photoreceptor apoptosis after retina-RPE separation.
Methods: :
Retina-RPE separation was created in Brown-Norway rats by injection of 1% hyaluronic acid into the subretinal space. Retinas were harvested 1-7 days after detachment, and assayed for Atg5 transcript and protein levels. Attached retinas served as controls. The Fas-dependence of Atg5 expression was tested in vitro in 661W cells stimulated with a Fas-receptor activating antibody, and in vivo using the Fas-receptor specific antagonist Met12. The effect of Atg5 in regulating photoreceptor apoptosis was tested by using siRNA to prevent the detachment-induced increase in Atg5 transcription.
Results: :
Retina-RPE separation results in a time-dependent increase in the levels of Atg5 transcript and protein. Fas-activation is necessary, but not sufficient, for increased Atg5 expression. A reliable system using siRNA has been developed to effectively knock-out Atg5 expression following retinal detachment, which can be used to study Atg5’s role in photoreceptor autophagy and apoptosis.
Conclusions: :
Retinal detachment increases the transcription and protein levels of Atg5, an autophagy factor that is proposed to induce apoptosis at the transition point between autophagy and apoptosis, in the neurosensory retina in a Fas-dependent manner. A system using siRNA has been created to knock-out Atg5 expression in the retina, and the effect of this on photoreceptor cell survival is currently being examined.
Keywords: retinal detachment • apoptosis/cell death • cell survival