Embryonic motor neuron programming factors reactivate immature gene expression and suppress ALS pathologies in postnatal motor neurons

Aging is a major risk factor in amyotrophic lateral sclerosis (ALS) and other adult-onset neurodegenerative disorders. Whereas young neurons are capable of buffering disease-causing stresses, mature neurons lose this ability and degenerate over time. We hypothesized that the resilience of young motor neurons could be restored by re-expression of the embryonic motor neuron selector transcription factors ISL1 and LHX3. We found that viral re-expression of ISL1 and LHX3 reactivates aspects of the youthful gene expression program in mature motor neurons and alleviates key disease-relevant phenotypes in the SOD1G93A mouse model of ALS. Our results suggest that redeployment of lineage-specific neuronal selector transcription factors can be an effective strategy to attenuate age-dependent phenotypes in neurodegenerative disease. Sun1-sfGFP-Myc mice were either injected with AAV-Isl1+AAV-Lhx3 at P1 (6 mice, Treatment group) or left untreated (8 mice, Control group). At P21 GFP+ nuclei were separately FAC sorted from treatment and control mice. Brachial and lumbar regions of the spinal cord were dissection and nuclei were isolated and sorted following the exact protocol detailed in Patel et al. 2022, Nature Communications. All nuclei collected (~60,000 from six treatment mice and ~80,000 from eight control mice) were taken to the Genome Center at Columbia University, where they were counted, and processed using 10x multiome kit and 10x Chromium. Data was pre-processed using CellRanger by the Genomics Core. Alignment of sequencing reads were performed using both the standard mm10 genome and a custom genome that included 4 extra genes present in the AAV driven mRNA- the hIsl1 and hLhx3 coding sequences, chimeric-intron, and WPRE.