Photoreceptor Protection by Adeno-Associated Virus-Mediated LEDGF Expression in the RCS Rat Model of Retinal Degeneration: Probing the Mechanism

• Published in: Investigative ophthalmology & visual science 2009-08, Vol.50 (8), p.3897-3906
• Main Authors: Raz-Prag, Dorit, Zeng, Yong, Sieving, Paul A, Bush, Ronald A
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Animals, Genetically Modified; Biological and medical sciences; Blotting, Western; Cell Count; Cell Survival; Cytoprotection; Dependovirus - genetics; Electroretinography; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - physiology; Genetic Therapy - methods; Genetic Vectors; HSP27 Heat-Shock Proteins - genetics; HSP27 Heat-Shock Proteins - metabolism; Medical sciences; Mutagenesis, Site-Directed; Ophthalmology; Photoreceptor Cells, Vertebrate - physiology; Plasmids; Rats; Rats, Mutant Strains; Retinal Degeneration - metabolism; Retinal Degeneration - physiopathology; Retinal Degeneration - therapy; Retinopathies; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Transduction, Genetic; Up-Regulation; Vertebrates: nervous system and sense organs
• ISSN: 0146-0404; 1552-5783; 1552-5783
• DOI: 10.1167/iovs.08-3153

Lens epithelium-derived growth factor (LEDGF) is upregulated in response to stress and enhances the survival of neurons in the retina and optic nerve, as well as a wide range of other cells, such as fibroblasts and keratinocytes. Photoreceptor protection was investigated in the RCS rat retinal degeneration model after Ledgf delivery with an adeno-associated virus (AAV) and the mechanism of protection explored. Thirty-six RCS and nine P23H rats had bilateral subretinal injections of AAV-Ledgf in one eye and buffer in the contralateral eye as the control. Retinal function was evaluated 8 weeks later by the electroretinogram and compared with photoreceptor cell layer count. LEDGF mRNA and protein levels and mRNA levels of known stress-related factors were compared in treated and control retinas to explore the mechanism of LEDGF protection. Nine RCS rats were treated with adenovirus-heat shock protein 27 (Ad-HSP27) and examined for protection. Significant photoreceptor protection was evident functionally and morphologically in 65% to 100% of the RCS rats treated at early ages of up to 7 weeks. Cell protection was more prominent in the superior retinal hemisphere which has a slower natural degeneration rate in untreated eyes. Although many of the heat shock proteins and other stress-related genes showed significant elevation in the AAV-Ledgf-treated eyes, all increases were approximately twofold or less. Transduction of retinal cells with Ad-HSP27 also resulted in photoreceptor protection. AAV-Ledgf elicited no photoreceptor functional protection in P23H rhodopsin transgenic rat retina. Chronic LEDGF treatment via AAV-Ledgf administration gave successful protection of photoreceptors in the RCS rat retina and retarded cell death by about 2 weeks. Induction of heat shock proteins also gave photoreceptor protection. However, compelling evidence was not found that LEDGF protection was associated with upregulation of heat shock proteins.