Activin A mitigates ferroptosis in cerebral ischemia/reperfusion injury via the PGC-1α/NRF1/TFAM axis

Cerebral ischemia/reperfusion (I/R) injury severely limits the efficacy of recanalization therapy for ischemic stroke. Activin A (Act A), a neurotrophic cytokine, shows protective potential, but its mechanisms related to mitochondrial biogenesis and ferroptosis regulation remain unclear.

In vivo, adult male Wistar rats (12/group) underwent 2 h middle cerebral artery occlusion (MCAO) and 24 h reperfusion. Act A (7.5 μg/kg) or vehicle was administered intracerebroventricularly pre-ischemia. TTC, TEM, and IHC were used to analyze cerebral I/R injury and PGC-1α expression. In vitro, HT22 cells exposed to oxygen-glucose deprivation/reoxygenation (OGD/R, 8 h/24 h) were treated with Act A (100 ng/mL). Ferroptosis markers, mitochondrial function and signaling pathways were assessed via qPCR, western blot, flow cytometry, laser confocal and ChIP.

In vivo, Act A significantly reduced cerebral infarct volume versus vehicle (***p < 0.001), decreased MDA levels (***p < 0.001), and increased PGC-1α expression (***p < 0.001) along with mtDNA copy number (*p < 0.05). In vitro, Act A rescued OGD/R-induced ferroptosis, suppressing lipid ROS (**p < 0.01) and Fe²⁺ accumulation (*p < 0.05). It activated the PGC-1α/NRF1/TFAM axis (*p < 0.05) and enhanced mitochondrial biogenesis. Mechanistically, Act A promoted PGC-1α transcription via Smad3 binding to its promoter (*p < 0.05) and enhanced PGC-1α activity through p38-MAPK phosphorylation (***p < 0.001). Silencing PGC-1α abolished Act A's neuroprotection effects.

Act A mitigates cerebral I/R injury by dual activation of PGC-1α through Smad3 and p38-MAPK pathways, enhancing mitochondrial biogenesis and inhibiting neuronal ferroptosis. This highlights Act A as a therapeutic candidate for ischemic stroke.