title: Lysosomal membrane permeabilization and autophagy blockade contribute to photoreceptor cell death in a mouse model of retinitis pigmentosa.
abstract: Retinitis pigmentosa is a group of hereditary retinal dystrophies that normally result in photoreceptor cell death and vision loss both in animal models and in affected patients. The rd10 mouse, which carries a missense mutation in the Pde6b gene, has been used to characterize the underlying pathophysiology and develop therapies for this devastating and incurable disease. Here we show that increased photoreceptor cell death in the rd10 mouse retina is associated with calcium overload and calpain activation, both of which are observed before the appearance of signs of cell degeneration. These changes are accompanied by an increase in the activity of the lysosomal protease cathepsin B in the cytoplasm of photoreceptor cells, and a reduced colocalization of cathepsin B with lysosomal markers, suggesting that lysosomal membrane permeabilization occurs before the peak of cell death. Moreover, expression of the autophagosomal marker LC3-II (lipidated form of LC3) is reduced and autophagy flux is blocked in rd10 retinas before the onset of photoreceptor cell death. Interestingly, we found that cell death is increased by the induction of autophagy with rapamycin and inhibited by calpain and cathepsin inhibitors, both ex vivo and in vivo. Taken together, these data suggest that calpain-mediated lysosomal membrane permeabilization underlies the lysosomal dysfunction and downregulation of autophagy associated with photoreceptor cell death.
authors.affiliation: Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maetzu 9, Madrid 28040, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Rodríguez-Muela
authors.affiliation: 3D Lab, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maetzu 9, Madrid 28040, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: Hernández-Pinto
authors.affiliation: Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maetzu 9, Madrid 28040, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Serrano-Puebla
authors.affiliation: Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maetzu 9, Madrid 28040, Spain.
authors.forename: L
authors.initials: L
authors.lastname: García-Ledo
authors.affiliation: Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maetzu 9, Madrid 28040, Spain.
authors.forename: S H
authors.initials: SH
authors.lastname: Latorre
authors.affiliation: 3D Lab, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maetzu 9, Madrid 28040, Spain.
authors.forename: E J
authors.initials: EJ
authors.lastname: de la Rosa
authors.affiliation: Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maetzu 9, Madrid 28040, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Boya
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002463:Cell Membrane Permeability / Q000502:physiology; D004195:Disease Models, Animal; D005260:Female; D008247:Lysosomes / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010786:Photoreceptor Cells / Q000166:cytology* / Q000378:metabolism*; D012174:Retinitis Pigmentosa / Q000378:metabolism* / Q000473:pathology*