Exogenous photoreceptor-specific N-glycosylated PROM1 rescues retinal degeneration in patient and mouse models

Abstract

Human prominin-1 (PROM1) is broadly expressed across multiple tissues. However, its pathogenic variants cause an exclusive retina-related disorder, PROM1-associated inherited retinal dystrophy (PROM1-IRD). The mechanistic basis underlying this tissue-specific vulnerability remains unclear, and no approved targeted therapy is available. Here, we used urine cells, human induced pluripotent stem cells (hiPSCs), hiPSC-retinal pigment epithelial cells, retinal organoids (ROs), and Prom1^-/- mice to address these challenges. During photoreceptor differentiation in ROs, PROM1 localized to the apical ciliary compartment and the outer segment (OS)-like structures, co-localizing with ARL13B and PRPH2, and displayed photoreceptor-enriched mRNA splicing isoforms and distinct N-glycosylation patterns. In models derived from an IRD patient harboring a homozygous PROM1 c.619G>T (p.E207×) mutation, PROM1 transcripts underwent both nonsense-mediated mRNA decay and nonsense-associated altered splicing, resulting in complete loss of PROM1 protein and severe disruption of OS-like structures. To restore PROM1 function, a photoreceptor-targeted AAV7m8-CRXp-hPROM1 vector was developed, which efficiently restored PROM1 expression and rescued OS-like structures in patient-derived ROs. In vivo, subretinal delivery of AAV8-CRXp-hPROM1 to Prom1^-/- mice produced sustained, photoreceptor-targeted expression of human PROM1, significantly preserving OS morphology and improving visual function. Collectively, these findings implicate a molecular basis for retinal vulnerability to PROM1 variants and provide compelling preclinical evidence supporting adeno-associated-virus-mediated gene augmentation as a therapeutic approach for PROM1-IRD.

Keywords: AAV; N-glycosylation; PROM1; gene therapy; inherited retinal dystrophy; nonsense mutation; photoreceptor outer segment; retinal organoids.