CRB1 is required for recycling by RAB11A+ vesicles in human retinal organoids

CRB1 gene mutations can cause early- or late-onset retinitis pigmentosa, Leber congenital amaurosis, or maculopathy. Recapitulating human CRB1 phenotypes in animal models has proven challenging, necessitating the development of alternatives. We generated human induced pluripotent stem cell (iPSC)-derived retinal organoids of patients with retinitis pigmentosa caused by biallelic CRB1 mutations and evaluated them against autologous gene-corrected hiPSCs and hiPSCs from healthy individuals. Patient organoids show decreased levels of CRB1 and NOTCH1 expression at the retinal outer limiting membrane. Proximity ligation assays show that human CRB1 and NOTCH1 can interact via their extracellular domains. CRB1 patient organoids feature increased levels of WDFY1+ vesicles, fewer RAB11A+ recycling endosomes, decreased VPS35 retromer complex components, and more degradative endolysosomal compartments relative to isogenic control organoids. Taken together, our data demonstrate that patient-derived retinal organoids enable modeling of retinal degeneration and highlight the importance of CRB1 in early endosome maturation receptor recycling in the retina. [Display omitted] •CRB1 is associated with retinitis pigmentosa•We made organoids from these patients and studied their biology•The extracellular domains of CRB1 and NOTCH1 interact•Our data link to altered endosomal maturation and increased autophagy Wijnholds, Buck, and colleagues detect upregulation of the endolysosome-associated gene Wdfy-1 in a Crb1 mouse model. They also show that the extracellular domains of human CRB1 and NOTCH1 interact and levels of WDFY1 increased in human retinal organoids, whereas levels of CRB1, NOTCH1, VPS35, and RAB11A decreased in CRB1-associated retinitis pigmentosa organoids. CRB1 organoids repressed early endosome maturation and increased endosomal degradative compartments.