K777 promotes functional recovery after spinal cord injury via the PI3K/AKT signaling pathway

Spinal cord injury (SCI) is a catastrophic neurological disorder leading to motor and sensory impairments. This study aimed to investigate the pathological changes following spinal cord injury and the therapeutic effects of K777, along with its underlying mechanisms. Microarray and single-nucleus RNA sequencing were used to analyze gene expression changes at 1 and 7-days post-injury, and identified the potential targets. Molecular docking screened potential therapeutic compounds, validated via histological and molecular experiments. Differential gene expression analysis in the microarray and single-nucleus RNA analysis revealed the dynamic changes and microenvironmental remodeling post-SCI, with GO-BP enrichment in neuronal apoptosis and oxidative stress. High-dimensional weighted gene co-expression network analysis revealed that Ctsb and Ctsl were two pivotal genes that were associated with neuronal viability. K777, a Ctsb/Ctsl inhibitor, significantly improved neuronal viability, reduced oxidative stress, inhibited neuronal apoptosis and the release of pro-inflammatory cytokines. Furthermore,K777 promoted axonal growth in dorsal root ganglia neurons. Multiple functional experiments in mice SCI model demonstrated that K777 promoted motor function recovery in mice without causing organ toxicity. Nissl staining indicated that K777 treatment significantly increased neuronal survival. Mechanistically, K777 activated the PI3K/AKT signaling pathway in a dose-dependent manner. Our findings demonstrate that K777 exerts neuroprotective effects through multiple mechanisms, suggesting its potential therapeutic value for SCI.