GSDME-N-induced mitochondrial neurotoxicity in early neurodegeneration was suppressed by nicotine via enhancing autophagic flux.

BACKGROUND: Neurodegeneration is a chronic, progressive process initiated by early neurite retraction, a pathological hallmark preceding neuronal death in neurodegenerative disorders such as Parkinson’s disease (PD). Cleavage of gasdermin E (GSDME) releases its N-terminal domain (GSDME-N), which has been shown to mediate mitochondrial dysfunction and the onset of neurodegeneration. However, the therapeutic potential of targeting GSDME-N for early intervention in PD, and whether nicotine, a tobacco component with neuroprotective properties, acts through GSDME modulation remain unexplored. METHODS: The SH-SY5Y cells, primary neurons and C57BL mice were treated with rotenone to model neurodegeneration in PD. Mitochondrial accumulation of GSDME-N and activation of autophagy were assessed via immunoblotting and immunostaining. Mitochondrial membrane potential was evaluated using JC-1 and TMRM fluorescent dyes, while mitochondrial reactive oxygen species were detected with MitoSOX™ Red superoxide indicator. For morphological analysis, immunofluorescence staining was performed using antibodies against microtubule-associated protein 2 (MAP2) to visualize neurites, along with MitoTracker to label mitochondria within neurites. In vivo, C57BL/6 mice were administered rotenone and provided with nicotine supplementation in their drinking water. Motor function was assessed using rotarod, hanging wire and pole tests. Tyrosine hydroxylase (TH)-positive neurons and fibers were detected using immunohistochemistry. RESULTS: We demonstrated that GSDME-N accumulation on mitochondria during early neurodegeneration was suppressed by nicotine, thereby maintaining mitochondrial homeostasis and preventing neurite retraction. Mechanistically, nicotine activated autophagic pathway to promote GSDME-N clearance, which maintained mitochondrial membrane potential, reduced reactive oxygen species (ROS) production, and specifically rescued mitochondrial function. This protective mechanism significantly attenuated early pathological changes, including neurite retraction and loss. In a rotenone-induced PD model, nicotine treatment effectively reduced GSDME-N accumulation and decelerated neurodegenerative progression. CONCLUSIONS: These findings reveal the critical role of GSDME-N in early-stage mitochondrial damage in PD and propose a novel therapeutic strategy targeting the nicotine-autophagy axis to counteract GSDME-N-mediated neurodegeneration.