MLST8 overexpression in RPE cells disrupts autophagy through novel mechanisms affecting AMD pathogenesis.

Abstract

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly, with dysfunction of the retinal pigment epithelium (RPE) central to disease pathogenesis. Using our uniquely developed MLST8 (MTOR associated protein, LST8 homolog) knock-in animal model with RPE-specific overexpression, which drives MTOR (mechanistic target of rapamycin kinase) upregulation, we demonstrate that increased MTOR complexes 1 and 2 in the RPE disrupts macroautophagy/autophagy by suppressing autophagosome formation genes and impairing MAP1LC3/LC3 processing. This leads to autophagosome accumulation and defective autolysosome formation, driving RPE dysfunction and AMD-like pathology, including subretinal debris build up and photoreceptor degeneration. Notably, MTOR inhibition with torin1 treatment or CRYBA1 overexpression rescues these defects, restoring autophagy and RPE integrity. Our findings reveal that autophagy disruption mediated by both MTORC1 and MTORC2 drives AMD-like pathology in our mouse model, establishing autophagy regulation as a promising avenue for therapeutic intervention in this vision-threatening disease.