Nr2e3 functional domain ablation by CRISPR-Cas9D10A identifies a new isoform and generates Retinitis Pigmentosa and Enhanced S-cone Syndrome models

Mutations in NR2E3 cause retinitis pigmentosa (RP) and enhanced S-cone syndrome (ESCS) in humans. This gene produces a large isoform encoded in 8 exons and a previously unreported shorter isoform of 7 exons, whose function is unknown. We generated two mouse models by targeting exon 8 of Nr2e3 using CRISPR/Cas9-D10A nickase. Allele {Delta}27 is an in-frame deletion of 27 bp that ablates the dimerization domain, whereas allele {Delta}E8 (full deletion of exon 8), produces only the short isoform that lacks the dimerization and repressor domains. The {Delta}27 mutant shows developmental alterations and a non-progressive electrophysiological dysfunction that resembles the ESCS phenotype. The {Delta}E8 mutant exhibits progressive retinal degeneration, as occurs in human RP patients. Interestingly, the mutant retinas show invaginations similar to fovea-like pits. Our mutants suggest a role of Nr2e3 as a cone-patterning regulator and provide valuable models for studying mechanisms of NR2E3-associated retinal dystrophies and evaluating potential therapies. O_FIG O_LINKSMALLFIG WIDTH=186 HEIGHT=200 SRC="FIGDIR/small/147785v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@1f5916forg.highwire.dtl.DTLVardef@11f1384org.highwire.dtl.DTLVardef@13a6cd2org.highwire.dtl.DTLVardef@be52b3_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- Nr2e3 mouse models were generated by exon 8 deletion using CRISPR/Cas9 D10A nickase. - New Nr2e3 mRNA retaining intron 7 encodes a short protein expressed in adult retina. - Deletion of 9 aa of the NR2E3 dimerization domain causes enhanced S-cone syndrome. - Deletion of exon 8 produces a phenotype similar to Retinitis Pigmentosa in mouse.