Morc2a variants cause hydroxyl radical-mediated neuropathy and are rescued by GHKL ATPase gene therapy
Mutations in the Microrchidia CW-Type Zinc Finger 2 (MORC2) GHKL ATPase module cause Charcot Marie Tooth type 2Z or a broad range of neuropathy, but etiology and therapeutic strategy are not fully defined. Previously, we reported that the Morc2a p.S87L mouse model led to neuropathy and muscular dysfunction through DNA damage accumulation. This study revealed that Morc2a p.S87L caused a protein synthesis defect, resulting in the loss of function of Morc2a and weakening its function of maintaining DNA integrity and hydroxyl radical scavenging in the GHKL ATPase domain. Morc2a GHKL ATPase domain was considered a therapeutic target based on its function of simultaneously complementing hydroxyl radical scavenging and ATPase activity. Adeno-associated virus PHP.eB serotype that has high central nervous system transduction efficiency was applied to express Morc2a or Morc2a GHKL ATPase domain protein in vivo. AAV gene therapy improved neuropathy and muscular dysfunction with single-time treatment. The loss of function characteristics due to protein synthesis defect in Morc2a p.S87L was also observed in human MORC2 p.S87L or p.R252W variant, suggesting a relevance between mouse and human pathogenesis. Here, we demonstrate Morc2a p.S87L variant causes hydroxyl radical-mediated neuropathy and could be rescued through AAV-based gene therapy. Overall design: RNA sequencing of spinal cord (SC) and mouse fetal fibroblast (MEF) of wild-type (WT) or Morc2a p.S87L heterozygote (S87L) mice (n=3 for WT-SC, S87L-SC, and WT-MEF; n=2 for S87L-MEF)