A missense mutation in human INSC causes peripheral neuropathy.

PAR3/INSC/LGN form an evolutionarily conserved complex required for asymmetric cell division in the developing brain, but its post-developmental function and disease relevance in the peripheral nervous system (PNS) remains unknown. We mapped a new locus for axonal Charcot–Marie-Tooth disease (CMT2) and identified a missense mutation c.209 T > G (p.Met70Arg) in the INSC gene. Modeling the INSC^M70R variant in Drosophila, we showed that it caused proprioceptive defects in adult flies, leading to gait defects resembling those in CMT2 patients. Cellularly, PAR3/INSC/LGN dysfunction caused tubulin aggregation and necrotic neurodegeneration, with microtubule-stabilizing agents rescuing both morphological and functional defects of the INSC^M70R mutation in the PNS. Our findings underscore the critical role of the PAR3/INSC/LGN machinery in the adult PNS and highlight a potential therapeutic target for INSC-associated CMT2. Synopsis: This study unveils the first discovery of an INSC gene missense mutation causing axonal Charcot-Marie-Tooth disease (CMT) and examines the microtubule-stabilizing role of PAR3/INSC/LGN in the adult peripheral nervous system (PNS). Microtubule-stabilizing agents effectively reverse proprioception defects and necrosis in INSC mutation individuals. Identification of INSC as a potential pathogenic gene in adult-onset peripheral neuropathy. Demonstration of PAR3/INSC/LGN dysfunction leading to proprioceptive defects resembling gait abnormalities in patients with CMT. Requirement of PAR3/INSC/LGN for microtubule stabilization in the adult PNS. Reversal of both morphological and functional defects in a disease model through the use of microtubule-stabilizing agents, presenting a potential therapeutic strategy for peripheral neuropathy. This study unveils the first discovery of an INSC gene missense mutation causing axonal Charcot-Marie-Tooth disease (CMT) and examines the microtubule-stabilizing role of PAR3/INSC/LGN in the adult peripheral nervous system (PNS). Microtubule-stabilizing agents effectively reverse proprioception defects and necrosis in INSC mutation individuals. [ABSTRACT FROM AUTHOR]