• Open Access

Selective silencing by RNAi of a dominant allele that causes amyotrophic lateral sclerosis


Zuoshang Xu, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605–2324, USA. Tel.: +1 508 856 3309; fax: +1 508 856 8390; e-mail: zuoshang.xu@umassmed.edu
Phillip Zamore, as above. Tel.: +1 508 856 2191; fax: +1 508 856 2003; e-mail: phillip.zamore@umassmed.edu


RNA interference (RNAi) can achieve sequence-selective inactivation of gene expression in a wide variety of eukaryotes by introducing double-stranded RNA corresponding to the target gene. Here we explore the potential of RNAi as a therapy for amyotrophic lateral sclerosis (ALS) caused by mutations in the Cu, Zn superoxide dismutase (SOD1) gene. Although the mutant SOD1 is toxic, the wild-type SOD1 performs important functions. Therefore, the ideal therapeutic strategy should be to selectively inhibit the mutant, but not the wild-type SOD1 expression. Because most SOD1 mutations are single nucleotide changes, to selectively silence the mutant requires single-nucleotide specificity. By coupling rational design of small interfering RNAs (siRNAs) with their validation in RNAi reactions in vitro and in vivo, we have identified siRNA sequences with this specificity. A similarly designed sequence, when expressed as small hairpin RNA (shRNA) under the control of an RNA polymerase III (pol III) promoter, retains the single-nucleotide specificity. Thus, RNAi is a promising therapy for ALS and other disorders caused by dominant, gain-of-function gene mutations.