GSK-3β inhibition elicits a neuroprotection by restoring lysosomal dysfunction in neurons via facilitation of TFEB nuclear translocation after ischemic stroke

Lysosomal dysfunction is an essential pathogenesis of autophagic neuronal injury after ischemic stroke. As a result of cerebral ischemia, transcription factor EB (TFEB) is greatly phosphorylated by prominently activated glycogen synthase kinase-3 beta (GSK-3 beta). This increased TFEB phosphorylation decreases its nuclear translocation and subsequently leads to reduced lysosomal biosynthesis, which ultimately results in lysosomal dysfunction. The present study is to investigate whether the lysosomal dysfunction in neurons can be restored to alleviate post-stroke damage by GSK-3 beta inhibition. The GSK-3 beta activity was inhibited by pre-treatment with CHIR-99021 (CHIR) for 3 days before middle cerebral artery occlusion (MCAO) surgery in rats. Besides, the lysosomal capacity was altered by pre-administration with Bafilomycin A1 (Baf-A1) and EN6, respectively. Twenty-four hours after MCAO/reperfusion, the penumbral tissues were obtained to detect the GSK-3 beta, cytoplasmic and nuclear TFEB, and proteins in autophagic/lysosomal pathway by western blot and immunofluorescence, respectively. Meanwhile, the infarct volume, neurological deficits and neuron survival were assessed to evaluate the neurological outcomes elicited by GSK-3 beta inhibition. The results demonstrated that the neurological injury could be significantly mitigated by GSK-3 beta inhibition in MCAO + CHIR group, compared with that in MCAO group. Moreover, CHIR-facilitated TFEB nuclear trans location in neurons was coupled with reinforced lysosomal activities and attenuated autophagic substrates. However, GSK-3 beta inhibition-induced neuroprotection was greatly counteracted by Baf-A1-weakened lysosomal capacity. Conversely, EN6-reinforced lysosomal activities further ameliorated the autophagic/lysosomal signaling, and synergistically alleviated the neurological damage upon GSK-3 beta inhibition after MCAO/reperfusion. Our data suggests that GSK-3 beta inhibition-augmented neuroprotection against ischemic stroke is elicited by restoring the lysosomal dysfunction in neurons.

Automated summary

This study investigated whether lysosomal dysfunction in neurons can be restored by inhibiting GSK-3β to alleviate post-stroke damage. The results showed that GSK-3β inhibition can significantly mitigate neurological injury in ischemic stroke, and the alteration of lysosomal capacity affects this neuroprotection.