A CEP290 C-Terminal Domain Complements the Mutant CEP290 of Rd16 Mice In Trans and Rescues Retinal Degeneration

Summary: Mutations in CEP290 cause ciliogenesis defects, leading to diverse clinical phenotypes, including Leber congenital amaurosis (LCA). Gene therapy for CEP290-associated diseases is hindered by the 7.4 kb CEP290 coding sequence, which is difficult to deliver in vivo. The multi-domain structure of the CEP290 protein suggests that a specific CEP290 domain may complement disease phenotypes. Thus, we constructed AAV vectors with overlapping CEP290 regions and evaluated their impact on photoreceptor degeneration in Cep290rd16/rd16 and Cep290rd16/rd16;Nrl−/− mice, two models of CEP290-LCA. One CEP290 fragment (the C-terminal 989 residues, including the domain deleted in mutant mice) reconstituted CEP290 function and resulted in cone preservation and delayed rod death. The CEP290 C-terminal domain also improved cilia phenotypes in mouse embryonic fibroblasts and iPSC-derived retinal organoids carrying the Cep290rd16 mutation. Our study strongly argues for in trans complementation of CEP290 mutations by a cognate fragment and suggests therapeutic avenues. : CEP290 mutations are the leading cause of Leber congenital amaurosis, a devastating inherited blindness. Mookherjee et al. show that the in-frame deletion of Cep290 in rd16 mice can be complemented by expressing a cognate protein fragment in trans, suggesting a new avenue for therapy development of CEP290 mutations. Keywords: CEP290, AAV, gene therapy, photoreceptors, retinal degeneration, LCA, ciliopathy