NADPH oxidase contributes to photoreceptor degeneration in constitutively active RAC1 mice

Hongman Song, Camasamudram Vijayasarathy, Yong Zeng, Dario Marangoni, Ronald A. Bush, Zhijian Wu, Paul A. Sieving

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Purpose: The active form of small GTPase RAC1 is required for activation of NADPH oxidase (NOX), which in turn generates reactive oxygen species (ROS) in nonphagocytic cells. We explored whether NOX-induced oxidative stress contributes to rod degeneration in retinas expressing constitutively active (CA) RAC1. Methods: Transgenic (Tg)–CA-RAC1 mice were given apocynin (10 mg/kg, intraperitoneal), a NOX inhibitor, or vehicle daily for up to 13 weeks. Superoxide production and oxidative damage were assessed by dihydroethidium staining and by protein carbonyls and malondialdehyde levels, respectively. Outer nuclear layer (ONL) cells were counted and electroretinogram (ERG) amplitudes measured in Tg-CA-RAC1 mice. Outer nuclear layer cells were counted in wild-type (WT) mice after transfer of CA-Rac1 gene by subretinal injection of AAV8-pOpsin-CA Rac1-GFP. Results: Transgenic-CA-RAC1 retinas had significantly fewer photoreceptor cells and more apoptotic ONL cells than WT controls from postnatal week (Pw) 3 to Pw13. Superoxide accumulation and protein and lipid oxidation were increased in Tg-CA-RAC1 retinas and were reduced in mice treated with apocynin. Apocynin reduced the loss of photoreceptors and increased the rod ERG a- and b-wave amplitudes when compared with vehicle-injected transgenic controls. Photoreceptor loss was also observed in regions of adult WT retina transduced with AAV8-pOpsin-CA Rac1-GFP but not in neighboring regions that were not transduced or in AAV8-pOpsin-GFP–transduced retinas. Conclusions: Constitutively active RAC1 promotes photoreceptor cell death by oxidative damage that occurs, at least partially, through NOX-induced ROS. Reactive oxygen species are likely involved in multiple forms of retinal degenerations, and our results support investigating RAC1 inhibition as a therapeutic approach that targets this disease pathway.

Original languageEnglish (US)
Pages (from-to)2864-2875
Number of pages12
JournalInvestigative Ophthalmology and Visual Science
Volume57
Issue number6
DOIs
StatePublished - May 1 2016
Externally publishedYes

Keywords

  • NADPH oxidase
  • Oxidative stress
  • Photoreceptor degeneration
  • RAC1
  • Reactive oxygen species

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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