Balance between autophagic pathways preserves retinal homeostasis

N Rodríguez‐Muela, H Koga, L García‐Ledo… - Aging cell, 2013 - Wiley Online Library
N Rodríguez‐Muela, H Koga, L García‐Ledo, P de la Villa, EJ De la Rosa, AM Cuervo
Aging cell, 2013Wiley Online Library
Aging contributes to the appearance of several retinopathies and is the largest risk factor for
aged‐related macular degeneration, major cause of blindness in the elderly population.
Accumulation of undegraded material as lipofuscin represents a hallmark in many
pathologies of the aged eye. Autophagy is a highly conserved intracellular degradative
pathway that plays a critical role in the removal of damaged cell components to maintain the
cellular homeostasis. A decrease in autophagic activity with age observed in many tissues …
Summary
Aging contributes to the appearance of several retinopathies and is the largest risk factor for aged‐related macular degeneration, major cause of blindness in the elderly population. Accumulation of undegraded material as lipofuscin represents a hallmark in many pathologies of the aged eye. Autophagy is a highly conserved intracellular degradative pathway that plays a critical role in the removal of damaged cell components to maintain the cellular homeostasis. A decrease in autophagic activity with age observed in many tissues has been proposed to contribute to the aggravation of age‐related diseases. However, the participation of different autophagic pathways to the retina physiopathology remains unknown. Here, we describe a marked reduction in macroautophagic activity in the retina with age, which coincides with an increase in chaperone‐mediated autophagy (CMA). This increase in CMA is also observed during retinal neurodegeneration in the Atg5flox/flox; nestin‐Cre mice, a mouse model with downregulation of macroautophagy in neuronal precursors. In contrast to other cell types, this autophagic cross talk in retinal cells is not bi‐directional and CMA inhibition renders cone photoreceptor very sensitive to stress. Temporal and cell‐type‐specific differences in the balance between autophagic pathways may be responsible for the specific pattern of visual loss that occurs with aging. Our results show for the first time a cross talk of different lysosomal proteolytic systems in the retina during normal aging and may help the development of new therapeutic intervention for age‐dependent retinal diseases.
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