Axon Regeneration and Functional Recovery from Spinal Cord Injury is Enhanced by Allele-Specific ApoE Neuronal Action through Lrp8

Adult CNS trauma frequently causes neuronal disconnection and persistent deficits due to failed axon regeneration. While model system screening has identified candidate neural repair genes, ApoE – LRP8 signaling is unique in being implicated clinically. Here, we show that cortical axon regeneration requires LRP8 and is modified by APOE variants. ApoE2-expressing mice show reparative corticospinal and raphespinal axon growth with greater motor function than controls after spinal cord injury. Distinct from ApoE in other settings, there is no change in inflammation or scarring. After axotomy, ApoE exerts allele_x0002_specific effects on LRP8 localization and signaling in cortical neurons. APOE alleles regulate synaptic organization gene expression by cortical neurons after injury, with little effect on glial gene expression. AAV-mediated overexpression of ApoE2 in mice after spinal trauma increased locomotor recovery and reparative axon growth. Thus, a role for ApoE – LRP8 signaling is supported by preclinical and clinical observations, providing a potential site for intervention.