LAUSR

An innovative approach for a rare disease Charcot-Marie-Tooth disease type 2A (CMT2A) is a rare, inherited neurodegenerative condition. Affected individuals develop severe progressive muscle weakness, motor deficits, and peripheral neuropathy. Although defects in the gene encoding mitofusin 2 (MFN2) are known to cause CMT2A, the disease remains incurable. Rocha et al. identified specific MFN2 residues contributing to the disease and developed a class of MFN2-agonist drugs. The small molecules restored mitochondrial fusion and activity in the sciatic nerves of mice; they may also help in other diseases linked to mitochondrial trafficking. Science, this issue p. 336 New insights provide a lead that may help to produce treatments for mitochondrial disease. Mitofusins (MFNs) promote fusion-mediated mitochondrial content exchange and subcellular trafficking. Mutations in Mfn2 cause neurodegenerative Charcot-Marie-Tooth disease type 2A (CMT2A). We showed that MFN2 activity can be determined by Met376 and His380 interactions with Asp725 and Leu727 and controlled by PINK1 kinase–mediated phosphorylation of adjacent MFN2 Ser378. Small-molecule mimics of the peptide-peptide interface of MFN2 disrupted this interaction, allosterically activating MFN2 and promoting mitochondrial fusion. These first-in-class mitofusin agonists overcame dominant mitochondrial defects provoked in cultured neurons by CMT2A mutants MFN2 Arg94→Gln94 and MFN2 Thr105→Met105, as demonstrated by amelioration of mitochondrial dysmotility, fragmentation, depolarization, and clumping. A mitofusin agonist normalized axonal mitochondrial trafficking within sciatic nerves of MFN2 Thr105→Met105 mice, promising a therapeutic approach for CMT2A and other untreatable diseases of impaired neuronal mitochondrial dynamism and/or trafficking.