TY - JOUR
T1 - Codon-Optimized RPGR Improves Stability and Efficacy of AAV8 Gene Therapy in Two Mouse Models of X-Linked Retinitis Pigmentosa
AU - Fischer, M. Dominik
AU - McClements, Michelle E.
AU - Martinez-Fernandez de la Camara, Cristina
AU - Bellingrath, Julia Sophia
AU - Dauletbekov, Daniyar
AU - Ramsden, Simon C.
AU - Hickey, Doron G.
AU - Barnard, Alun R.
AU - MacLaren, Robert E
PY - 2017
Y1 - 2017
N2 - X-linked retinitis pigmentosa (XLRP) is generally a severe form of retinitis pigmentosa, a neurodegenerative, blinding disorder of the retina. 70% of XLRP cases are due to mutations in the retina-specific isoform of the gene encoding retinitis pigmentosa GTPase regulator (RPGR ORF15 ). Despite successful RPGR ORF15 gene replacement with adeno-associated viral (AAV) vectors being established in a number of animal models of XLRP, progression to human trials has not yet been possible. The inherent sequence instability in the purine-rich region of RPGR ORF15 (which contains highly repetitive nucleotide sequences) leads to unpredictable recombination errors during viral vector cloning. While deleted RPGR may show some efficacy in animal models, which have milder disease, the therapeutic effect of a mutated RPGR variant in patients with XLRP cannot be predicted. Here, we describe an optimized gene replacement therapy for human XLRP disease using an AAV8 vector that reliably and consistently produces the full-length correct RPGR protein. The glutamylation pattern in the RPGR protein derived from the codon-optimized sequence is indistinguishable from the wild-type variant, implying that codon optimization does not significantly alter post-translational modification. The codon-optimized sequence has superior stability and expression levels in vitro. Significantly, when delivered by AAV8 vector and driven by the rhodopsin kinase promoter, the codon-optimized RPGR rescues the disease phenotype in two relevant animal models (Rpgr -/y and C57BL/6J Rd9/Boc ) and shows good safety in C57BL6/J wild-type mice. This work provides the basis for clinical trial development to treat patients with XLRP caused by RPGR mutations. X-linked retinitis pigmentosa caused by mutations in RPGR is a frequent cause of retinal degeneration and blindness without available treatment. Fischer et al. demonstrate safety and efficacy of gene supplementation in relevant animal models using a codon-optimized transgene, thereby resolving the problem of sequence instability of wild-type RPGR.
AB - X-linked retinitis pigmentosa (XLRP) is generally a severe form of retinitis pigmentosa, a neurodegenerative, blinding disorder of the retina. 70% of XLRP cases are due to mutations in the retina-specific isoform of the gene encoding retinitis pigmentosa GTPase regulator (RPGR ORF15 ). Despite successful RPGR ORF15 gene replacement with adeno-associated viral (AAV) vectors being established in a number of animal models of XLRP, progression to human trials has not yet been possible. The inherent sequence instability in the purine-rich region of RPGR ORF15 (which contains highly repetitive nucleotide sequences) leads to unpredictable recombination errors during viral vector cloning. While deleted RPGR may show some efficacy in animal models, which have milder disease, the therapeutic effect of a mutated RPGR variant in patients with XLRP cannot be predicted. Here, we describe an optimized gene replacement therapy for human XLRP disease using an AAV8 vector that reliably and consistently produces the full-length correct RPGR protein. The glutamylation pattern in the RPGR protein derived from the codon-optimized sequence is indistinguishable from the wild-type variant, implying that codon optimization does not significantly alter post-translational modification. The codon-optimized sequence has superior stability and expression levels in vitro. Significantly, when delivered by AAV8 vector and driven by the rhodopsin kinase promoter, the codon-optimized RPGR rescues the disease phenotype in two relevant animal models (Rpgr -/y and C57BL/6J Rd9/Boc ) and shows good safety in C57BL6/J wild-type mice. This work provides the basis for clinical trial development to treat patients with XLRP caused by RPGR mutations. X-linked retinitis pigmentosa caused by mutations in RPGR is a frequent cause of retinal degeneration and blindness without available treatment. Fischer et al. demonstrate safety and efficacy of gene supplementation in relevant animal models using a codon-optimized transgene, thereby resolving the problem of sequence instability of wild-type RPGR.
KW - Codon optimization
KW - Gene therapy
KW - Retina
UR - http://www.scopus.com/inward/record.url?scp=85019636192&partnerID=8YFLogxK
U2 - 10.1016/j.ymthe.2017.05.005
DO - 10.1016/j.ymthe.2017.05.005
M3 - Article
AN - SCOPUS:85019636192
SN - 1525-0016
JO - Molecular Therapy
JF - Molecular Therapy
ER -