Article: article from journal or magazin.
Early apoptosis of rod photoreceptors in Rpe65(-/-) mice is associated with the upregulated expression of lysosomal-mediated autophagic genes.
Experimental Eye Research
Publication types: Journal Article ; Research Support, Non-U.S. Gov'tPublication Status: ppublish
RPE65-related Leber's congenital amaurosis (LCA) is a rod-cone dystrophy whose clinical outcome is mainly attributed to the loss of rod photoreceptors followed by cone degeneration. Pathogenesis in Rpe65(-/-) mice is characterized by a slow and progressive degeneration of rods dependent on the constitutive activation of unliganded opsin. We previously reported that this opsin-mediated apoptosis of rods was dependent on Bcl-2-apoptotic pathway and Bax-induced pro-death activity. In this study, we report early initial apoptosis in the newly differentiated retina of Rpe65(-/-) mice. Apoptotic photoreceptors were identified as rods and resulted from pathological phototransduction signaling. This wave of early apoptosis triggered Bcl-2-related pathway and Bax apoptotic activity, while activation of the caspases was not induced. Following cellular stress, multiple signaling pathways are initiated which either commit cells to death or trigger pro-survival responses including autophagy. We report that Bcl-2-related early rod apoptosis was associated with the upregulation of autophagy markers including chaperone-mediated autophagy (CMA) substrate receptor LAMP-2 and lysosomal hydrolases Cathepsin S and Lysozyme. This suggests that lysosomal-mediated autophagy may be triggered in response to early rod apoptosis in Rpe65-LCA disease. These results highlight that Rpe65-related primary stress induces early signaling events, which trigger Bax-induced-apoptotic pathway and autophagy-mediated cellular response. These events may determine retinal cell fate, progression and severity of the disease.
Animals, Apoptosis, Autophagy, Blotting, Western, Carrier Proteins/genetics, Cathepsins/genetics, Eye Proteins/genetics, Fluorescent Antibody Technique, Indirect, Gene Expression Regulation/physiology, Genotyping Techniques, In Situ Nick-End Labeling, Leber Congenital Amaurosis/genetics, Leber Congenital Amaurosis/pathology, Lysosomal-Associated Membrane Protein 2/genetics, Mice, Mice, Inbred BALB C, Mice, Inbred C57BL, Mice, Knockout, Muramidase/genetics, Proto-Oncogene Proteins c-bcl-2/genetics, Real-Time Polymerase Chain Reaction, Retinal Rod Photoreceptor Cells/pathology, bcl-2-Associated X Protein/genetics
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