In vitro modeling and rescue of ciliopathy associated with mutations in IQCB1 (Nephrocystin 5) using patient-derived cells

Mutations in IQCB1/NPHP5 gene encoding the ciliary protein Nephrocystin 5 cause early-onset blinding disease Leber congenital amaurosis (LCA), together with kidney dysfunction in Senior-Løken Syndrome. For in vitro disease modeling, we obtained dermal fibroblasts from NPHP5-LCA patients, which were reprogrammed into induced pluripotent stem cells (iPSCs) and differentiated into retinal pigment epithelium (RPE) and retinal organoids. Patient fibroblasts and RPE demonstrated aberrantly elongated ciliary axonemes. Organoids revealed impaired development of outer segment structures, which are modified primary cilia, and mislocalization of visual pigments to photoreceptor cell soma. All patient-derived cells showed reduced levels of CEP290 protein, a critical cilia transition zone component interacting with NPHP5, providing a plausible mechanism for aberrant ciliary gating and cargo transport. Disease phenotype in NPHP5-LCA retinal organoids could be rescued by AAV-mediated NPHP5 gene augmentation therapy. Our studies thus establish a human disease model and a path for treatment of NPHP5-LCA. RNA was extracted from 3 frozen organoids per sample. Each group of control (804), untreated patient and patient with AAV treatment contains triple samples.