Investigating therapeutic nonsense suppression in a neurofibromatosis mouse model

Abstract

Neurofibromatosis type 1 (NF1) is a human genetic disorder caused by variants in the NF1 gene. Plexiform neurofibromas, one of many NF1 manifestations, are benign peripheral nerve sheath tumors occurring in up to 50% of NF1 patients. A substantial fraction of NF1 pathogenetic variants are nonsense mutations, which result in the synthesis of truncated non-functional NF1 protein (neurofibromin). To date, no therapeutics have restored neurofibromin expression or addressed the consequences of this protein's absence in NF1 nonsense mutation patients, but nonsense suppression is a potential approach to the problem. Ataluren is a small molecule drug that has been shown to stimulate functional nonsense codon readthrough in several models of nonsense mutation diseases, as well as in Duchenne muscular dystrophy patients. To test ataluren's potential applicability in nonsense mutation NF1 patients, we evaluated its therapeutic effects using three treatment regimens in a previously established NF1 patient-derived (c.2041C > T; p.Arg681X) nonsense mutation mouse model. Collectively, our experiments indicate that: i) ataluren appeared to slow the growth of neurofibromas and alleviate some paralysis phenotypes, ii) female Nf1-nonsense mutation mice manifested more severe paralysis and neurofibroma phenotypes than male mice, iii) ataluren doses with apparent effectiveness were lower in female mice than in male mice, and iv) age factors also influenced ataluren's effectiveness.