LncRNA NORAD Promotes Spinal Cord Injury via miR-22-3p/PTEN Axis to Regulate Oxidative Stress and Inflammation in Neuronal Cells.

Study DesignRetrospective Study.ObjectiveSpinal cord injury (SCI) is a severe central nervous system trauma. To explore the regulatory mechanism of long non-coding RNA (lncRNA) NORAD in SCI.MethodsEighty healthy controls and 100 SCI patients were enrolled. Meanwhile, SCI animal models and LPS-induced cell models were established. Basso-Beattie-Bresnahan (BBB) scoring was performed to monitor hind-limb motor recovery. The NORAD biological function was evaluated through RT-qPCR, CCK-8 experiments, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and the measurement of oxidative stress and metabolism-related indicators. The targeting relationships were verified through RIP experiments and dual-luciferase experiments.ResultsNORAD exhibited high expression in SCI patients and possessed good diagnostic utility for this disease. Its high expression may also be associated with the severity of injury. In SCI rats, inhibiting NORAD significantly improved the recovery of motor function and alleviated oxidative stress, cellular damage, and neuroinflammation, indicating a pro-injury role of NORAD during SCI pathogenesis. In addition, NORAD was highly expressed in the LPS-induced cell model, and promoted cellular damage, apoptosis, inflammatory responses, and oxidative stress by targeting and inhibiting miR-22-3p. While miR-22-3p directly targeted and inhibited PTEN, which was also highly expressed in the LPS-induced cell model. Functional rescue experiments further confirmed that the miR-22-3p inhibitor could reverse the protective effect of interfering with NORAD on SCI-related pathological damage, while silencing PTEN could offset the antagonistic effect of the miR-22-3p inhibitor, suggesting that the NORAD/miR-22-3p/PTEN axis constituted a positive feedback pro-injury loop.ConclusionsNORAD sequestered miR-22-3p to relieve PTEN repression and exacerbate SCI.