title: MicroRNA-restricted transgene expression in the retina.
abstract: BACKGROUND
  Gene transfer using adeno-associated viral (AAV) vectors has been successfully applied in the retina for the treatment of inherited retinal dystrophies. Recently, microRNAs have been exploited to fine-tune transgene expression improving therapeutic outcomes. Here we evaluated the ability of retinal-expressed microRNAs to restrict AAV-mediated transgene expression to specific retinal cell types that represent the main targets of common inherited blinding conditions.
  
  
  RESULTS
  To this end, we generated AAV2/5 vectors expressing EGFP and containing four tandem copies of miR-124 or miR-204 complementary sequences in the 3'UTR of the transgene expression cassette. These vectors were administered subretinally to adult C57BL/6 mice and Large White pigs. Our results demonstrate that miR-124 and miR-204 target sequences can efficiently restrict AAV2/5-mediated transgene expression to retinal pigment epithelium and photoreceptors, respectively, in mice and pigs. Interestingly, transgene restriction was observed at low vector doses relevant to therapy.
  
  
  CONCLUSIONS
  We conclude that microRNA-mediated regulation of transgene expression can be applied in the retina to either restrict to a specific cell type the robust expression obtained using ubiquitous promoters or to provide an additional layer of gene expression regulation when using cell-specific promoters.
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy.
authors.forename: Marianthi
authors.initials: M
authors.lastname: Karali
authors.forename: Anna
authors.initials: A
authors.lastname: Manfredi
authors.forename: Agostina
authors.initials: A
authors.lastname: Puppo
authors.forename: Elena
authors.initials: E
authors.lastname: Marrocco
authors.forename: Annagiusi
authors.initials: A
authors.lastname: Gargiulo
authors.forename: Mariacarmela
authors.initials: M
authors.lastname: Allocca
authors.forename: Michele Della
authors.initials: MD
authors.lastname: Corte
authors.forename: Settimio
authors.initials: S
authors.lastname: Rossi
authors.forename: Massimo
authors.initials: M
authors.lastname: Giunti
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Bacci
authors.forename: Francesca
authors.initials: F
authors.lastname: Simonelli
authors.forename: Enrico Maria
authors.initials: EM
authors.lastname: Surace
authors.forename: Sandro
authors.initials: S
authors.lastname: Banfi
authors.forename: Alberto
authors.initials: A
authors.lastname: Auricchio
mesh_terms: D000818:Animals; D001483:Base Sequence; D000229:Dependovirus / Q000235:genetics; D005786:Gene Expression Regulation; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000378:metabolism; D034421:Sus scrofa; D014161:Transduction, Genetic; D019076:Transgenes / Q000235:genetics*
chemical_list: D035683:MicroRNAs; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins