Peripheral nervous system defects in a mouse model for peroxisomal biogenesis disorders

• Mouse Pex10 model displays progressive loss of movement during late embryogenesis.
• Pex10CY/CY embryos show phenotypic and biochemical hallmarks of PBD.
• Pex10CY/CY embryos display characteristic signs of defects in axon integrity.
• Pex10CY/CY embryos have misplaced Schwann Cells along axons and at synapses.
• Pex10CY/CY phrenic axons extend beyond defective synapses in muscle.

Peroxisome biogenesis disorders (PBD) are autosomal recessive disorders in humans characterized by skeletal, eye and brain abnormalities. Despite the fact that neurological deficits, including peripheral nervous system (PNS) defects, can be observed at birth in some PBD patients including those with PEX10 mutations, the embryological basis of the PNS defects is unclear. Using a forward genetic screen, we identified a mouse model for Pex10 deficiency that exhibits neurological abnormalities during fetal development. Homozygous Pex10 mutant mouse embryos display biochemical abnormalities related to a PBD deficiency. During late embryogenesis, Pex10 homozygous mutant mice experience progressive loss of movement and at birth they become cyanotic and die shortly thereafter. Homozygous Pex10 mutant fetuses display decreased integrity of axons and synapses, over-extension of axons in the diaphragm and decreased Schwann cell numbers. Our neuropathological, molecular and electrophysiological studies provide new insights into the embryological basis of the PNS deficits in a PBD model. Our findings identify PEX10 function, and likely other PEX proteins, as an essential component of the spinal locomotor circuit.