AMPKα1 activation enhances mitophagy to counteract hypoxia-induced neuronal apoptosis in cervical spondylotic myelopathy and facilitates functional recovery mediated by rosmarinic acid.

BACKGROUND: Cervical spondylotic myelopathy (CSM) involves progressive neurological dysfunction often linked to mitochondrial impairment. Mitophagy, a selective autophagic process, is crucial for neuronal homeostasis; however, its role in CSM and the specific involvement of AMPK subunits in TFEB-mediated mitophagy remain unclear. Rosmarinic acid (RA) is known for neuroprotection and mitophagy activation, but its exact mechanism in CSM has not yet been clarified. METHODS: We investigated the neuroprotective efficacy of RA using a rat model of chronic spinal cord compression, alongside oxygen-glucose deprivation (OGD)-challenged primary neurons and PC12 cells. To dissect the roles of AMPK subunits, PC12 lines with individual (a1-KO, a2-KO) or combined (a1/a2-DKO) deficiencies were employed. Mitophagy, lysosomal integrity, and signaling pathways were assessed via RNA-seq, immunofluorescence (IF), transmission electron microscopy, and Western blot. PURPOSE: To investigate the role of the AMPKα1-TFEB signaling axis in regulating mitophagy in CSM and to identify RA as a potent neuroprotective agent. RESULTS: Our findings indicate that while chronic hypoxia induces severe neuronal apoptosis, transient hypoxia enhances mitophagy and preserves lysosomal integrity via the AMPK-TFEB signaling pathway. Notably, Prkaa1 knockout or a1/a2 double-knockout PC12 cells exhibited exacerbated apoptosis and impaired mitophagy/lysosomal function under hypoxic challenge, whereas no significant differences were observed in Prkaa2 knockout cells. Furthermore, RA was found to restore impaired spinal cord function by activating the AMPK-TFEB axis. CONCLUSION: AMPKα1 is a pivotal regulator of the AMPK-TFEB/mitophagy axis. Targeting AMPKα1 or utilizing RA represents a promising therapeutic strategy for CSM, although further well-designed randomized controlled trials are required to evaluate clinical efficacy.