The role of the RET protein in the perihematomal region after intracerebral hemorrhage

Following intracerebral hemorrhage (ICH), neurons surrounding the hematoma are highly vulnerable yet potentially salvageable. Our previous gene chip analysis suggested that the ASCL1-RET signaling axis is involved in neural injury after ICH. This study aimed to investigate the role and mechanism of RET in the perihematomal region after ICH. We established an in vivo mouse model of ICH and in vitro primary astrocyte and neuronal culture models. RET expression and phosphorylation were examined by Western blotting and immunofluorescence. RET was silenced in astrocytes using shRNA lentivirus. Neuronal apoptosis was assessed by TUNEL assay and cleaved caspase-3 expression. The PI3K/AKT pathway was examined to explore the underlying mechanism. p-RET expression was significantly upregulated in the perihematomal region after ICH, peaking at day 1 and co-localizing with neurons, astrocytes, and microglia. Hemin stimulation of primary astrocytes induced astrocyte reactivity and RET phosphorylation. Conditioned medium from hemin-stimulated astrocytes reduced neuronal apoptosis, an effect abolished by RET knockdown in astrocytes. Changes in PI3K/AKT phosphorylation were associated with RET-dependent astrocyte-mediated neuroprotection. Astrocytic RET protects neurons from hemin-induced apoptosis and is associated with modulation of PI3K/AKT signaling, supporting a RET-dependent contribution to astrocyte-neuron crosstalk and suggesting RET as a potential therapeutic target for neuroprotection after ICH.