Targeting Lysosomes to Reverse Hydroquinone-Induced Autophagy Defects and Oxidative Damage in Human Retinal Pigment...

Area of Science:

• Ophthalmology
• Cell Biology
• Toxicology

Background:

• Oxidative damage in retinal pigment epithelium (RPE) is implicated in age-related macular degeneration (AMD).
• The roles of autophagy and the ubiquitin-proteasome system in modulating hydroquinone (HQ)-induced RPE damage are unclear.

Purpose of the Study:

• To investigate the mechanisms underlying HQ-induced oxidative damage in human RPE cells.
• To explore the involvement of autophagy and lysosomal function in this process.
• To evaluate the therapeutic potential of lysosomal stabilizers.

Main Methods:

• Incubation of human RPE cells (ARPE-19) with HQ to create an in-vitro AMD model.
• Assessment of reactive oxygen species (ROS), oxidative damage markers (protein carbonyls), mitochondrial function, and cell viability.
• Analysis of autophagy flux, proteasome activity, and lysosomal integrity (LAMP2, cathepsin D, pH).
• Evaluation of MG132 (proteasome inhibitor/lysosomal stabilizer) effects on HQ-induced damage.

Main Results:

• HQ induced significant oxidative damage, mitochondrial dysfunction, and reduced cell viability, with less ROS production compared to H2O2.
• HQ blocked autophagy flux, increased proteasome activity, and impaired lysosomal function (decreased LAMP2/cathepsin D, alkalization).
• MG132 pretreatment restored LAMP2 and autophagy, protected against HQ-induced damage in wildtype RPE cells.

Conclusions:

• Lysosomal dysfunction is a key factor in autophagy defects and oxidative damage caused by HQ in RPE cells.
• Impaired lysosomal membrane integrity and alkalization contribute to HQ toxicity.
• Lysosomal stabilization using MG132 shows promise for treating oxidative damage in RPE relevant to AMD.