Novel Candidate Gene for Congenital Stationary Night Blindness Characterized in a CRISPR-Cas9 Knockout Mouse Model

Riley Arbuckle - Final Dissertation Defense - HUGEN PhD Candidate Department of Human Genetics Doctoral Candidate, Riley Arbuckle, will defend the following dissertation on “Novel Candidate Gene for Congenital Stationary Night Blindness Characterized in a CRISPR-Cas9 Knockout Mouse Model” COMMITTEE CHAIR: Yuanyuan Chen, PhD Committee Members: F. Yesim Demirci, MDCheng Zhang, PhDQuasar S. Padiath, PhD, MBBS ABSTRACT: Congenital Stationary Night Blindness (CSNB) is a nonprogressive, inherited retinal disease marked by reduced scotopic vision, altered photopic vision, and impaired dark adaptation. Many G-protein-coupled receptors (GPCRs), such as rhodopsin or metabotropic glutamate receptor 6 and GPR179, are implicated in retinal diseases, including CSNB. The orphan GPCR GPR152 is highly expressed in rods and cones, and localizes to the outer segment of both photoreceptors, with its retinal function uncharacterized. This study aims to characterize the of GPR152 in the retina, using a Gpr152 knockout (KO) mouse model, generated via CRISPR/Cas9 deletion of the entire open reading frame in exon 2. We evaluated retinal function and morphology by spectral-domain optical coherence tomography (SD-OCT), fundus imaging, optodrum, and full-field electroretinogram (ERG) from P45 through P365 with transcriptional profiling by RNA-seq. Ultrastructural changes were examined via transmission electron microscopy (TEM). The Gpr152-/- mice experienced a reduction of scotopic ERG a- and b-waves from P90 which remained stable over time until P365. The photopic responses of the Gpr152-/- mice remained similar to WT levels, suggesting a rod-selective requirement of this gene. Retinal structure remained normal by SD-OCT, TEM, and fundus imaging throughout the KO mice’s lifespan, parallelling the nonprogressive, structurally normal phenotype seen in human CSNB patients. Gene Ontology showed loss of Gpr152 leading to the downregulation of genes involved in genes synapses and the v