Paeoniflorin suppresses ferroptosis after traumatic brain injury by antagonizing P53 acetylation.

BACKGROUND: Traumatic brain injury (TBI) could induce multiple forms of cell death, ferroptosis, a novel form of cell death distinct from apoptosis and autophagy, plays an important role in disease progression in TBI. Therapies targeting ferroptosis are beneficial for recovery from TBI. Paeoniflorin (Pae) is a water-soluble monoterpene glycoside and the active ingredient of Paeonia lactiflora pall. It has been shown to exert anti-inflammatory and antioxidant effects. However The effects and mechanisms of paeoniflorin on secondary injury after TBI are unknown. PURPOSE: To investigate the mechanism by which Pae regulates ferroptosis after TBI. METHODS: The TBI mouse model and cortical primary neurons were utilized to study the protective effect of paeoniflorin on the brain tissue after TBI. The neuronal cell ferroptosis model was established by treating cortical primary neurons with erastin. Liproxstatin-1(Lip-1) was used as a positive control drug. Immunofluorescence staining, Nissl staining, biochemical analyses, pharmacological analyses, and western blot were used to evaluate the effects of paeoniflorin on TBI. RESULTS: Pae significantly ameliorated neuronal damage after TBI, inhibited mitochondrial damage, increased glutathione peroxidase 4 (GPX4) activity, decreased malondialdehyde (MDA) production, restored neurological function and inhibited cerebral edema. Pae promotes the degradation of P53 in the form of proteasome, promotes its ubiquitination, and reduces the stability of P53 by inhibiting its acetylation, thus alleviating the P53-mediated inhibition of cystine/glutamate antiporter solute carrier family 7 member 11 (SLC7A11) by P53. CONCLUSION: Pae inhibits ferroptosis by promoting P53 ubiquitination out of the nucleus, inhibiting P53 acetylation, and modulating the SLC7A11-GPX4 pathway.

Inhibition of USP30 Promotes Mitophagy by Regulating Ubiquitination of MFN2 by Parkin to Attenuate Early Brain Injury After SAH.

Subarachnoid hemorrhage (SAH) is a type of stroke with a high disability and mortality rate. Apoptosis caused by massive damage to mitochondria in neuron cells and inflammatory responses caused by high extracellular ATP lead to poor outcomes. USP30 is a deubiquitinating enzyme that inhibits mitophagy, resulting in a failure to remove damaged mitochondria in a timely manner after SAH; nevertheless, the pathway through which USP30 inhibits mitophagy is unknown. This study evaluated the neuroprotective role and possible molecular basis by which inhibiting USP30 to attenuate SAH-induced EBI by promoting neuronal mitophagy. We used an in vitro model of hemoglobin exposure and an in vivo model of intravascular perforation. Increased expression of USP30 was found after SAH in vivo and in vitro, and USP30 inhibition expression in SAH mice treated with MF094 resulted in significant improvement of neurological injury and inflammatory response and mediated good outcomes, suggesting a neuroprotective effect of USP30 inhibition. In cultured neurons, inhibition of USP30 promoted ubiquitination modification of mitochondrial fusion protein 2 (MFN2) by E3 ubiquitin ligase (Parkin), separating damaged mitochondria from the healthy mitochondrial network and prompting mitophagy, causing early clearance of damaged intracellular mitochondria, and reducing the onset of apoptosis. The high extracellular ATP environment was meliorated, reversing the conversion of microglia to a pro-inflammatory phenotype and reducing inflammatory injury. USP30 inhibition had no autophagy-promoting effect on structurally and functionally sound mitochondria and did not inhibit normal intracellular ATP production. The findings suggest that USP30 inhibition has a neuroprotective effect after SAH by promoting early mitophagy after SAH to clear damaged mitochondria.