title: ER stress is involved in T17M rhodopsin-induced retinal degeneration.
abstract: OBJECTIVE
  The human rhodopsin (Rho) mutation T17M leads to autosomal dominant retinitis pigmentosa (adRP). The goal of our study was to elucidate the role of endoplasmic reticulum (ER) stress in retinal degeneration in hT17M Rho mice and identify potential candidates for adRP gene therapy.
  
  
  METHODS
  We used transgenic mice expressing the ER stress-activated indicator (ERAI) and hT17M Rho to evaluate the activation of ER stress responses. Quantitative reverse transcription PCR (qRT-PCR) was used to analyze changes in the expression of 30 unfolded protein response (UPR)-associated genes at P12, 15, 18, 21, and 25. The cytosolic fraction of hT17M Rho retinal cells was used to measure the release of cytochrome C and apoptotic inducing factor-1 (AIF1) by Western blotting. Optical coherence tomography (OCT) analysis was performed for 1-month-old hT17M Rho mice.
  
  
  RESULTS
  hT17M Rho was localized in the outer nuclear layer (ONL) of T17M(+/-)ERAI(+/-) photoreceptors as well as C57BL/6 retinas injected with AAV-hT17M Rho-GFP. In P15 hT17M Rho retinas, we observed an up-regulation of UPR genes (Atf4, Eif2α, Xbp1, Bip, Canx, and Hsp90), autophagy genes and proapoptotic Bcl2 genes. OCT, and the downregulation of Nrl and Crx gene expression confirmed that cell death occurs in 55% of photoreceptors via the up-regulation of caspase-3 and caspase-12, and the release of AIF1 from the mitochondria.
  
  
  CONCLUSIONS
  The ER stress response is involved in retinal degeneration in hT17M Rho mice. The final demise of photoreceptors occurs via apoptosis involving ER stress-associated and mitochondria-induced caspase activation. We identified Atg5, Atg7, Bax, Bid, Bik, and Noxa as potential therapeutic targets for adRP treatment.
authors.affiliation: Department of Cell Biology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA.
authors.forename: Mansi M
authors.initials: MM
authors.lastname: Kunte
authors.forename: Shreyasi
authors.initials: S
authors.lastname: Choudhury
authors.forename: Jessica F
authors.initials: JF
authors.lastname: Manheim
authors.forename: Vishal M
authors.initials: VM
authors.lastname: Shinde
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miura
authors.forename: Vince A
authors.initials: VA
authors.lastname: Chiodo
authors.forename: William W
authors.initials: WW
authors.lastname: Hauswirth
authors.forename: Oleg S
authors.initials: OS
authors.lastname: Gorbatyuk
authors.forename: Marina S
authors.initials: MS
authors.lastname: Gorbatyuk
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D001343:Autophagy / Q000235:genetics; D015153:Blotting, Western; D053454:Caspase 12 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress / Q000235:genetics*; D019254:Genes, bcl-2; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D012162:Retinal Degeneration / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012243:Rhodopsin / Q000235:genetics*; D041623:Tomography, Optical Coherence; D056811:Unfolded Protein Response / Q000235:genetics
chemical_list: D051033:Apoptosis Inducing Factor; D003574:Cytochrome c Group; D012243:Rhodopsin; D053454:Caspase 12; D053148:Caspase 3