Abstract
Purpose :
RP33 is a non-syndromic form of RP caused by mutations in the SNRNP200 gene encoding an essential component of the spliceosome that is required for pre-mRNA splicing. SNRNP200 is expressed in nearly all cells, yet defects are only observed in the retina. To understand the function of SNRNP200 in vision, we generated Drosophila models.
Methods :
The Drosophila orthologue of human SNRNP200 is lethal(3)72Ab, which we refer to as dSNRNP200. Human SNRNP200 and fly dSNRNP200 have 74% amino acid identity and 89% similarity. To understand disease mechanisms, we analyzed the developing retina and performed electroretinograms (ERG) of adult Drosophila using RNAi knock-down and patient based CRISPR mutant alleles of dSNRNP200.
Results :
RNAi knock-down of dSNRNP200 in the developing eye increased apoptosis in the larval eye discs relative to controls and produced an adult “rough eye” phenotype. Similarly, a CRISPR mutant allele increased apoptosis in larval eye discs relative to controls. ERGs performed on young adults bearing the CRISPR mutant alleles exhibited abnormal waveforms indicative of loss of phototransduction and synaptic transmission that progressed with age, similar to the human disease condition. In addition, loss of prolonged depolarizing afterpotential indicated that the “rod-like” cells of the retina were defective. By contrast, the cone-like cells appeared functional, recapitulating early stages of the human disease.
Conclusions :
Globally expressed dSNRNP200 is essential for Drosophila photoreceptor function. Modeling RP33 mutations in the fly recapitulated many aspects of the human disease, which will allow for a molecular dissection of disease mechanisms and genetic and pharmacological screens for potential treatments.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.