Piezo1 Modulates Neuronal Autophagy and Apoptosis in Cerebral Ischemia-Reperfusion Injury Through the AMPK-mTOR Signaling Pathway

Abstract

Cerebral ischemia-reperfusion (I/R) injury is a complex pathophysiological process involving multiple mechanisms, including apoptosis and autophagy, which can lead to significant neuronal damage. PIEZO1, a stretch-activated ion channel, has recently emerged as a potential regulator of cellular responses to ischemic conditions. However, its role in neuronal cell survival and death during ischemic events is not well elucidated. This study aimed to ascertain the regulatory function of PIEZO1 in neuronal cell apoptosis and autophagy in an in vitro model of hypoxia-reoxygenation and an in vivo model of brain I/R injury. HT22 hippocampal neuronal cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate ischemic conditions, with subsequent reoxygenation. In vitro, PIEZO1 expression was silenced using small interfering RNA (si-RNA) transfection. The effects on cell viability, apoptosis, and autophagy were assessed using CCK-8 assays, PI-Annexin/V staining combined with flow cytometry, and Western blot analysis. Additionally, intracellular Ca²⁺ levels in HT22 cells were measured using a Ca²⁺ probe. The involvement of the AMPK-mTOR pathway was investigated using rapamycin. For in vivo validation, middle cerebral artery occlusion/reperfusion (MCAO/R) in rats was employed. To determine the neuroprotective role of PIEZO1 silencing, sh-PIEZO1 adeno-associated virus was stereotaxically injected into the cerebral ventricle, and neurological and histological outcomes were assessed using neurological scoring, TTC staining, H&E staining, Nissl staining, and immunofluorescence. In HT22 cells, OGD/R injury notably upregulated PIEZO1 expression and intracellular Ca²⁺ levels. Silencing PIEZO1 significantly diminished OGD/R-induced Ca²⁺ influx, apoptosis, and autophagy, as indicated by lower levels of pro-apoptotic and autophagy-related proteins and improved cell viability. Additionally, PIEZO1 modulated the AMPK-mTOR signaling pathway, an effect that was counteracted by rapamycin treatment, implying its regulatory role. In vivo, PIEZO1 silencing ameliorated brain I/R injury in MCAO/R rats, demonstrated by improved neurological function scores and reduced neuronal apoptosis and autophagy. However, these neuroprotective effects were reversed through rapamycin treatment. Our findings indicate that PIEZO1 is upregulated following ischemic injury and facilitates Ca²⁺ influx, apoptosis, and autophagy via the AMPK-mTOR pathway. Silencing PIEZO1 confers neuroprotection against I/R injury both in vitro and in vivo, highlighting its potential as a therapeutic target for stroke management.

Keywords: AMPK-mTOR pathway; Apoptosis; Autophagy; Ischemia–reperfusion injury; Neuroprotection; PIEZO1.