NADPH Oxidase Contributes to Photoreceptor Degeneration in Constitutively Active RAC1 Mice

Area of Science:

• Ophthalmology
• Molecular Biology
• Cell Biology

Background:

• The small GTPase RAC1 is crucial for activating NADPH oxidase (NOX).
• NOX generates reactive oxygen species (ROS), contributing to oxidative stress in nonphagocytic cells.
• The role of NOX-induced oxidative stress in retinal degeneration, particularly in rod cells, is not fully understood.

Purpose of the Study:

• To investigate if NOX-induced oxidative stress contributes to rod degeneration in retinas expressing constitutively active (CA) RAC1.
• To explore the therapeutic potential of inhibiting NOX in this context.

Main Methods:

• Transgenic mice (Tg-CA-RAC1) were treated with apocynin (a NOX inhibitor) or vehicle.
• Superoxide production and oxidative damage markers were assessed.
• Photoreceptor cell counts and electroretinogram (ERG) amplitudes were measured.
• Gene transfer of CA-RAC1 into wild-type retinas was performed using AAV8.

Main Results:

• Tg-CA-RAC1 retinas showed significant photoreceptor loss and increased apoptosis compared to controls.
• Apocynin treatment reduced oxidative stress markers and protected photoreceptor cells.
• Apocynin treatment improved ERG amplitudes in Tg-CA-RAC1 mice.
• Direct expression of CA-RAC1 in wild-type retinas induced photoreceptor loss.

Conclusions:

• Constitutively active RAC1 promotes photoreceptor cell death through NOX-induced oxidative stress.
• ROS play a role in various retinal degenerations.
• Targeting RAC1 inhibition presents a potential therapeutic strategy for retinal degenerative diseases.