Knock-down DHDDS expression induces photoreceptor degeneration in zebrafish

Area of Science:

• Genetics
• Neuroscience
• Ophthalmology

Background:

• Recessive retinitis pigmentosa (RP) is a group of inherited retinal diseases.
• A dehydrodolichol diphosphate synthase (DHDDS) mutation is linked to a subtype of RP.
• Molecular modeling suggests this mutation impairs DHDDS enzymatic efficiency.

Purpose of the Study:

• To investigate the link between reduced DHDDS activity and photoreceptor degeneration.
• To determine if insufficient DHDDS function contributes to retinal degeneration.

Main Methods:

• Knocked down DHDDS expression in zebrafish using morpholino oligonucleotides (MO).
• Assessed visual function by observing response to light-off stimuli.
• Analyzed retinal morphology and cone outer segment integrity using peanut agglutinin (PNA) staining.

Main Results:

• Zebrafish injected with MO showed normal general appearance but failed to respond to light-off stimuli, indicating visual impairment.
• Morphological analysis revealed significantly shortened or absent photoreceptor outer segments in MO-injected zebrafish retinas.
• PNA staining confirmed the absence of cone outer segments, demonstrating a specific loss of cone photoreceptors.

Conclusions:

• Suppression of DHDDS expression in zebrafish leads to photoreceptor outer segment loss and impaired visual function.
• These findings support the hypothesis that insufficient DHDDS function is a cause of retinal degeneration.
• DHDDS plays a critical role in maintaining photoreceptor structure and visual function.