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

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.