Piezo2 inhibition enhances the survival and axonal regeneration of spinal motoneurons after brachial plexus avulsion

Piezo-type mechanosensitive ion channel component 2 (Piezo2) is a mechanosensitive ion channel that plays essential roles in various biological processes, such as the maintenance of sensory neuron functionality. However, the role of Piezo2 in neuronal death and axonal regeneration following brachial plexus avulsion, a severe mechanical injury to spinal motoneurons, remains to be elucidated. In the present study, we therefore investigated the role of Piezo2 in neuronal death and axonal regeneration following brachial plexus avulsion. In adult Piezo2 floxed mice, Piezo2 knockdown in spinal motoneurons by infection with recombinant AAV-hSyn-Cre enhanced neuronal survival, axonal regeneration, and functional recovery following brachial plexus avulsion. This finding was further validated by treatment with the Piezo2 inhibitor D-GsMTx4. However, the constitutive conditional knockout of Piezo2 in spinal motoneurons did not affect motor network development. In primary spinal motoneuron cultures, Piezo2 inhibition reduced injury-induced calcium influx, thereby promoting neurite outgrowth. In vivo calcium imaging revealed that brachial plexus avulsion caused the elevation of calcium signals in the ventral horn of injured spinal cords, and that Piezo2 knockdown effectively compromised brachial plexus avulsion-induced calcium influx. RNA sequencing analysis demonstrated that Piezo2 knockdown altered the transcriptional profiles of injured spinal samples; differently expressed genes were clustered in calcium signaling and neuroinflammation-related signaling pathways. Additionally, Piezo2 knockdown significantly alleviated brachial plexus avulsion-induced glial responses. Collectively, our results indicate that brachial plexus avulsion-induced calcium overload in spinal motoneurons is dependent on Piezo2, and suggest that Piezo2 inhibition may be a novel therapeutic strategy for promoting neuronal survival, axonal regeneration, and functional improvement following brachial plexus avulsion.