PRCD is essential for high-fidelity photoreceptor disc formation

Area of Science:

• Ophthalmology
• Cell Biology
• Genetics

Background:

• Progressive rod-cone degeneration (PRCD) is a protein implicated in photoreceptor function.
• Mutations in PRCD cause blindness in humans and dogs, but its precise role remains unclear.

Purpose of the Study:

• To elucidate the function of PRCD in photoreceptor outer segment development and survival.
• To investigate the consequences of PRCD deficiency at the molecular and cellular level.

Main Methods:

• Generation and analysis of a PRCD knockout mouse model.
• Microscopic examination of photoreceptor outer segment disc morphogenesis.
• Assessment of vesicle formation, accumulation, and clearance mechanisms.

Main Results:

• PRCD knockout mice exhibit defects in nascent photoreceptor disc flattening, leading to vesicle budding.
• Accumulated vesicles in the interphotoreceptor matrix are poorly cleared by the retinal pigment epithelium.
• Microglia attempt to clear vesicles but are insufficient, resulting in progressive photoreceptor degeneration.

Conclusions:

• PRCD is essential for maintaining the apposition of new disc membranes during photoreceptor disc morphogenesis.
• Proper disc morphogenesis mediated by PRCD is critical for photoreceptor survival.
• Dysfunctional PRCD leads to a unique pathology involving vesicle accumulation and subsequent retinal degeneration.