Tanshinone IIA promotes mitophagy by inhibiting the MARCHF5-mediated ubiquitination and degradation of FUNDC1 to alleviate spinal cord injury

Background: Spinal cord injury (SCI) has a poor prognosis and lacks effective treatment options. Dysfunction of Mitophagy is involved in neuronal damage after SCI, and tanshinone IIA (TIIA) can regulate this process. This study aimed to investigate whether TIIA exerts neuroprotective effects by regulating Mitophagy and the underlying mechanisms.

Methods: A modified Allen weight-drop method was used to strike the exposed T8-T10 thoracic spinal segments to establish a mouse model of SCI. PC12 cells were treated with nerve growth factor (NGF) to induce a neuronal phenotype, followed by oxygen-glucose deprivation (OGD) to establish an in vitro SCI model. The Basso Mouse Scale (BMS) was used to assess hindlimb motor function in mice; HE and Nissl staining were used to evaluate spinal cord tissue pathology; TUNEL and CCK-8 assays were used to assess cell damage; and Western blotting and immunofluorescence were performed to determine protein expression.

Results: TIIA inhibited neuronal cell damage in SCI models and improved hindlimb motor function in SCI mice. Additionally, TIIA reactivated Autophagy in PC12 cells after OGD, whereas the inhibitory effect of TIIA on cell damage was weakened after treatment with the Autophagy inhibitor Mdivi-1. Co-IP revealed that MARCHF5 binds to FUNDC1. TIIA activates Mitophagy by inhibiting the MARCHF5-mediated ubiquitination and degradation of FUNDC1, and overexpression of MARCHF5 or knockdown of FUNDC1 can partially counteract the inhibitory effect of TIIA on the progression of SCI in mice.

Conclusion: TIIA alleviates neuronal cell damage by inhibiting the MARCHF5-mediated ubiquitination and degradation of FUNDC1 to activate Mitophagy, thereby ameliorating the progression of SCI.