PARP1 gene knock-out increases resistance to retinal degeneration without affecting retinal function

Area of Science:

• Ophthalmology
• Neuroscience
• Genetics

Background:

• Retinitis pigmentosa (RP) is an inherited retinal disease causing blindness.
• Poly(ADP-ribose) polymerase (PARP) activation is implicated in photoreceptor cell death in RP models.
• The specific role of PARP1, a predominant isoform, in RP pathogenesis was unclear.

Purpose of the Study:

• To investigate the role of PARP1 in photoreceptor degeneration in the context of RP.
• To determine if PARP1 is essential for normal retinal structure and function.
• To evaluate the therapeutic potential of targeting PARP1 in RP.

Main Methods:

• Utilized PARP1 knockout (KO) mice and wild-type (wt) littermates.
• Performed in vivo and ex vivo morphological and functional analyses (OCT, histology, ERG).
• Used retinal explant cultures and phosphodiesterase-6 (PDE6) inhibition to induce photoreceptor degeneration.

Main Results:

• PARP1 KO mice exhibited normal retinal morphology and function compared to wt.
• Retinal explants from wt mice showed significant photoreceptor degeneration upon PDE6 inhibition.
• Photoreceptor degeneration was substantially reduced in PARP1 KO retinal explants under pathological conditions.

Conclusions:

• PARP1 is dispensable for normal retinal function but crucial for photoreceptor degeneration under pathological stress.
• PARP-dependent cell death (PARthanatos) plays a significant role in retinal degeneration.
• Targeting PARP1 with inhibitors presents a promising therapeutic avenue for treating RP.