Defective chaperone-mediated autophagy in the retinal pigment epithelium of age-related macular degeneration patients.

Autophagy is one of the main intracellular recycling systems and its impairment is considered a primary hallmark of the aging process. Defective macroautophagy in the retinal pigment epithelium (RPE) has been described in age-related macular degeneration (AMD), a blindness-causing disease that affects roughly 200 million patients worldwide. The relevance of chaperone-mediated autophagy (CMA), a selective type of autophagy for proteins containing a KFERQ-like motif, in RPE cell biology and homeostasis remains to be elucidated. Here we describe decreased CMA activity in the RPE of AMD patients compared to healthy age-matched controls, along with accumulation of substrate proteins, and in donor-derived iPSC-RPE cells, which we used to further characterize AMD-associated alterations of cellular homeostasis derived from proteotoxicity. Treatment with CA77.1 (CMA activator) restores proteostasis and remodels specific subsets of the proteome in cells from healthy and AMD donors. CA77.1-treated AMD iPSC-RPE display reduced oxidative stress and improved mitochondrial function. These findings may explain the specific vulnerability of the RPE during AMD and shed light on CMA as a new druggable target for this as-of-now incurable disease.