Combined RNAinterfering and gene therapy targeting MFN2 for the treatment of Charcot-Marie-Tooth type 2A

Mitofusin-2 (MFN2) is an outer mitochondrial membrane protein essential for mitochondrial networking in most cells. Autosomal dominant mutations in the MFN2 gene cause Charcot-Marie-Tooth type 2A disease (CMT2A), a severe and disabling sensory-motor neuropathy with impact on the entire nervous system. To date, no curative treatment is available. In the paper we propose a novel therapeutic strategy tailored to correct the root genetic defect of CMT2A. In our approach, while mutant and wild-type MFN2 mRNA are inhibited by RNA interference (RNAi), the wild-type protein is restored by overexpressing a cDNA encoding a functional MFN2, modified to be resistant to RNAi. This strategy allows proper MFN2 molecular correction in vivo in the MitoCharc1 CMT2A transgenic mouse model after cerebrospinal fluid (CSF) delivery of the constructs via adenoassociated virus 9 (AAV9) in newborn mice. To identify the therapeutic molecular mechanisms and the pathway that are modulated, we have compared the bulk RNA expression profile of spinal cord from one month old wild type (WT) mice and MitoCharc1 transgenic mice (B6;D2-Tg(Eno2-MFN2*R94Q)L51Ugfm/J) which encode the mutant human MFN2*R94Q under the neuron specific rat enolase (Eno2) promoter, as potential mouse model to test the therapeutic approach. We performed gene expression profiling analysis using data (RNA-seq) obtained from 4 wild type mice and 8 MitoCharch1 transgenic mice at one time point. Overall design: Comparative gene expression profiling analysis of RNA-seq data from WT mice and its derivatives (CMT2A).