Small Extracellular Vesicle-Associated MiRNAs in Polarized Retinal Pigmented Epithelium

Area of Science:

• Cell Biology
• Molecular Biology
• Ophthalmology

Background:

• Oxidative stress in retinal pigmented epithelium (RPE) is linked to age-related macular degeneration (AMD).
• Endocytic trafficking and extracellular vesicle (EV) secretion are crucial for RPE function.
• Polarized secretion of EVs by RPE cells is not fully understood.

Purpose of the Study:

• To investigate if RPE cells secrete microRNAs (miRNAs) packaged into EVs in a polarized manner.
• To determine if RPE-secreted EVs contribute to maintaining RPE homeostasis under oxidative stress.
• To test the hypothesis that RPE miRNAs in EVs are secreted directionally.

Main Methods:

• Primary porcine RPE (pRPE) cells were cultured under chronic oxidative stress conditions.
• Small EVs (sEVs) were isolated from apical and basal conditioned media using two ultracentrifugation methods.
• sEV miRNA content was analyzed using miRNA-Seq and validated with qRT-PCR.

Main Results:

• Distinct miRNA profiles were identified in apically and basally secreted sEVs.
• miR-182 and miR-183 were enriched in apical sEVs; miR-122 was enriched in basal sEVs under homeostatic conditions.
• Oxidative stress led to a significant decrease in miR-183 levels within apically released sEVs.

Conclusions:

• RPE cells exhibit polarized secretion of specific miRNAs via sEVs.
• Oxidative stress alters the miRNA cargo of secreted sEVs.
• Polarized miRNA secretion in EVs may play a role in RPE homeostasis and AMD pathogenesis.