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.